CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of the earlier filing dates of U.S. Provisional Patent Application No. 63/491,937, filed March 23, 2023, and U.S. Provisional Patent Application No. 63/414,293, filed October 7, 2022. The entire disclosures of U.S. Patent Application Nos. 63/491,937 and 63/414,293 are each incorporated by reference herein in their entireties.

FIELD

[0002] The present disclosure relates to hydrothermal liquefaction processes and systems for producing biocrude using steam heat recovery.

ACKNOWLEDGMENT OF GOVERNMENT SUPPORT

[0003] This invention was made with Government support under Contract DE-AC0576RL01830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.

BACKGROUND

[0004] Hydrothermal liquefaction (HTL) is a processing technique than can convert a wide range of waste biological materials into a hydrocarbon liquid with similar properties to crude oil, often referred to as “biocrude.” Many HTL systems comprise heat exchangers for heating the waste biological materials, but such heat exchangers can be subject to fouling due to the presence of salt and CO2 in the waste biological materials. Fouling on heat exchangers and other hot surfaces can decrease HTL energy efficiency by restricting flow and increasing pressure loss. Furthermore, many HTL systems operate at high temperatures and pressures, requiring heat exchangers with extremely thick metal walls which increase the cost of the HTL systems. Finally, many HTL systems require heat exchangers with large heat transfer surface areas due to the high viscosity of process fluids flowing through the HTL systems. The high viscosity of HTL process fluids results in laminar flow with poor heat transport properties and large temperature gradients near heat transfer surfaces.

[0005] Accordingly, a need exists for improved hydrothermal liquefaction processes and systems that address such deficiencies. SUMMARY

[0006] The present disclosure relates to apparatuses, systems, methods, and processes pertaining to hydrothermal liquefaction using vaporized water and hot byproduct gases from the HTL process as a heat exchange medium.

[0007] In some examples, a hydrothermal liquefaction (HTL) reactor system can comprise a biomass slurry source.

[0008] In some examples, the HTL reactor system can comprise a mixing vessel disposed downstream of the biomass slurry source, wherein the mixing vessel can be configured to mix a biomass slurry stream received from the biomass slurry source with a vaporized water and gas byproducts stream.

[0009] In some examples, the HTL reactor system can comprise a pump disposed downstream of the mixing vessel, wherein the pump can be configured to pressurize a biomass slurry stream received from the mixing vessel.

[0010] In some examples, the HTL reactor system can comprise a HTL reactor section disposed downstream of the pump, wherein the HTL reactor section can be configured to produce a product mixture stream from a biomass slurry stream received from the pump.

[0011] In some examples, the HTL reactor system can comprise a pressure letdown valve disposed downstream of the HTL reactor section, wherein the pressure letdown valve can be configured to reduce the pressure of a product mixture stream received from the HTL reactor section.

[0012] In some examples, the HTL reactor system can comprise a vapor-liquid disengagement vessel disposed downstream of the pressure letdown valve, wherein the vapor-liquid disengagement vessel can be configured to separate vaporized water and gas byproducts from a product mixture stream received from the pressure letdown valve, and wherein the separated vaporized water and gas byproducts can form the vaporized water and gas byproducts stream received by the mixing vessel.

[0013] In some examples, the HTL reactor section can comprise an autothermal HTL reactor.

[0014] In some examples, the mixing vessel can be a first mixing vessel and the HTL reactor system can further comprise a second mixing vessel disposed downstream of the pump.

[0015] In some examples, the second mixing vessel can be configured to provide a vaporized water and gas byproducts stream to the first mixing vessel. [0016] In some examples, the pressure letdown valve can be a second pressure letdown valve and the vapor-liquid disengagement vessel can be a second vapor-liquid disengagement vessel.

[0017] In some examples, the HTL reactor system can further comprise a first vapor-liquid disengagement vessel disposed upstream of the second pressure letdown valve and the HTL reactor system can further comprise a first pressure letdown valve disposed upstream of the first vaporliquid disengagement vessel.

[0018] In some examples, the HTL reactor system can further comprise an excess steam outlet coupled to an outlet of the first vapor-liquid disengagement vessel.

[0019] In some examples, the HTL reactor system can further comprise a heat exchanger disposed downstream of the HTL reactor section.

[0020] In some examples, the heat exchanger can be configured to recover heat from the product mixture stream.

[0021] In some examples, the heat exchanger can be a first heat exchanger in a heat transfer liquid circuit of the HTL reactor system,

[0022] In some examples, the heat transfer liquid circuit can further comprise a second heat exchanger disposed upstream of the HTL reactor section.

[0023] In some examples, the heat transfer liquid circuit can be configured to circulate heat transfer liquid heated in the first heat exchanger to the second heat exchanger to heat a biomass slurry stream entering the HTL reactor section.

[0024] In some examples, the pressure of the biomass slurry stream entering the HTL reactor section can be a first pressure and the pressure of the heat transfer liquid circulating through the heat transfer liquid circuit can be a second pressure.

[0025] In some examples, the first pressure can be higher than the second pressure.

[0026] In one representative example, a hydrothermal liquefaction (HTL) reactor system can comprise a biomass slurry source, a mixing vessel disposed downstream of the biomass slurry source, a pump disposed downstream of the mixing vessel, a HTL reactor section disposed downstream of the pump, a pressure letdown valve disposed downstream of the HTL reactor section, and a vapor-liquid disengagement vessel disposed downstream of the pressure letdown valve. The mixing vessel can be configured to mix a biomass slurry stream received from the biomass slurry source with a vaporized water and gas byproducts stream. The pump can be configured to pressurize a biomass slurry stream received from the mixing vessel. The HTL reactor section can be configured to produce a product mixture stream from a biomass slurry stream received from the pump. The pressure letdown valve can be configured to reduce the pressure of a product mixture stream received from the HTL reactor section. The vapor- liquid disengagement vessel can be configured to separate vaporized water and gas byproducts from a product mixture stream received from the pressure letdown valve. The separated vaporized water and gas byproducts can form the vaporized water and gas byproducts stream received by the mixing vessel.

[0027] In one representative example, a hydrothermal liquefaction (HTL) process can comprise, in a mixing vessel, mixing a biomass slurry stream with a vaporized water and gas byproducts stream to heat the biomass slurry stream.

[0028] In some examples, the HTL process can comprise pressurizing a biomass slurry stream received from the mixing vessel.

[0029] In some examples, the HTL process can comprise flowing the biomass slurry stream through a HTL reactor to produce a product mixture stream including biocrude oil and water.

[0030] In some examples, the HTL process can comprise, in a flashing process, reducing the pressure of the product mixture stream to produce the vaporized water and gas byproducts stream.

[0031] In some examples, mixing the biomass slurry stream with the second vaporized water and gas byproducts stream can form a third vaporized water and gas byproducts stream.

[0032] In some examples, mixing the biomass slurry stream with the first vaporized water and gas byproducts stream can further comprise mixing the biomass slurry stream with the third vaporized water and gas byproducts stream.

[0033] In some examples, the flashing process can be a second flashing process occurring in a second vapor-liquid disengagement vessel.

[0034] In some examples, the HTL process further can comprise, before the second flashing process, reducing the pressure of the product mixture stream in a first flashing process occurring in a first vapor-liquid disengagement vessel to produce the second vaporized water and gas byproducts stream.

[0035] In some examples, the product mixture stream subject to the first flashing process can be received from the HTL reactor.

[0036] In some examples, the product mixture stream subject to the second flashing process can be received from the first vapor- liquid disengagement vessel. [0037] In some examples, the first flashing process can vaporize 5% to 50% of water in the product mixture stream.

[0038] In some examples, the second flashing process can vaporize 10% to 30% of water in the product mixture stream.

[0039] In some examples, the HTL process can further comprise removing offgas from the mixing vessel.

[0040] In some examples, the offgas can comprise 25% to 45% CO2.

[0041] In some examples, the HTL process can further comprise, before flowing the biomass slurry stream through the HTL reactor, transferring heat from a heat transfer liquid stream to the biomass slurry stream in a first heat exchanger.

[0042] In some examples, the HTL process which can further comprise, after flowing the biomass slurry stream through the HTL reactor, transferring heat from the product mixture stream to the heat transfer liquid stream in a second heat exchanger.

[0043] In some examples, the HTL process which can further comprise, after flowing the biomass slurry stream through the HTL reactor, circulating the heat transfer liquid stream from the second heat exchanger to the first heat exchanger.

[0044] In some examples, the HTL process can further comprise, concurrently with flowing the biomass slurry stream through the HTL reactor, injecting oxygen into the HTL reactor.

[0045] In some examples, the HTL process can further comprise, in the flashing process, producing an excess steam stream.

[0046] In one representative example, a hydrothermal liquefaction (HTL) reactor system can comprise a biomass slurry source, a mixing vessel disposed downstream of the biomass slurry source, a pump disposed downstream of the mixing vessel, a HTL reactor section disposed downstream of the pump, a pressure letdown valve disposed downstream of the HTL reactor section, and a vapor-liquid disengagement vessel disposed downstream of the pressure letdown valve. The mixing vessel can be configured to mix a biomass slurry stream received from the biomass slurry source with a vaporized water and gas byproducts stream. The pump can be configured to pressurize a biomass slurry stream received from the mixing vessel. The HTL reactor section can be configured to produce a product mixture stream from a biomass slurry stream received from the pump. The pressure letdown valve can be configured to reduce the pressure of a product mixture stream received from the HTL reactor section. The vapor- liquid disengagement vessel can be configured to separate vaporized water and gas byproducts from a product mixture stream received from the pressure letdown valve. The separated vaporized water and gas byproducts can form the vaporized water and gas byproducts stream received by the mixing vessel

[0047] In one representative examples, a hydrothermal liquefaction (HTL) process can comprise: in a mixing vessel, mixing a biomass slurry stream with a vaporized water and gas byproducts stream to heat the biomass slurry stream; pressurizing a biomass slurry stream received from the mixing vessel; flowing the biomass slurry stream through a HTL reactor to produce a product mixture stream including biocrude oil and water; and in a flashing process, reducing the pressure of the product mixture stream to produce the vaporized water and gas byproducts stream

[0048] In some examples, a HTL reactor system and/or process can comprise one or more of the components and/or unit operations recited in Examples 1-20 below.

[0049] The foregoing and other objects, features, and advantages of the disclosed technology will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG. 1 is a schematic diagram of a hydrothermal liquefaction (HTL) reactor system comprising one heat exchanger for a one-stage heat recovery process, according to one example.

[0051] FIG. 2 is a schematic diagram of a HTL reactor system comprising three heat exchangers for a two-stage heat recovery process, according to one example.

[0052] FIG. 3 is a schematic diagram of a HTL reactor system comprising mixing vessels and flash tanks for a flash heat recovery process, according to one example.

[0053] FIG. 4 is a side view of a low pressure section of a HTL reactor system comprising mixing vessels for a flash heat recovery process, according to one example.

[0054] FIG. 5 is a schematic diagram of a HTL reactor system comprising mixing vessels and flash tanks for a flash heat recover)' process, according to another example.

[0055] FIG. 6 is a schematic diagram of a HTL system comprising mixing vessels and vapor-liquid disengagement vessels for a flash heat recovery process, according to a third example.

[0056] FIG. 7 is a schematic diagram of a HTL reactor system comprising mixing vessels and flash tanks for a flash heat recover)' process, according to a fourth example. [0057] FIG. 8A is a phase diagram illustrating the temperature and pressure of HTL reactor effluent during a one-step cooling process, according to one example.

[0058] FIG. 8B is a phase diagram illustrating the temperature and pressure of HTL reactor effluent during a two-step cooling process, according to one example.

[0059] FIG. 9 is a schematic diagram of a HTL reactor system comprising modular heat recovery assemblies for a flash heat recovery process, according to one example.

[0060] FIG. 10 is a perspective view a HTL reactor system comprising modular heat recovery assemblies for a flash heat recovery process, according to one example.

[0061] FIG. 11 is a process flow diagram illustrating a method of producing biocrude using steam heat recovery, according to one example.

[0062] FIG. 12 is a schematic diagram of a wet air oxidation reactor system, according to one example.

[0063] FIG. 13 is a schematic diagram of a supercritical water oxidation reactor system, according to one example.

[0064] FIG. 14 is a schematic diagram of an autothermal HTL reactor system comprising an autothermal HTL reactor section, according to one example.

[0065] FIG. 15 is a chart showing a carbon balance breakdown for a typical HTL experiment, according to one example.

[0066] FIG. 16 is table illustrating chemical structures of several types of hydrocarbons present in feedstock, according to one example.

[0067] FIG. 17 is a graph comparing biocrude yields for multiple feedstocks, according to one example.

[0068] FIG. 18 is a graph comparing product phase yields for multiple feedstocks, according to one example.

[0069] FIGS. 19A-19C are graphs comparing fuel properties when upgraded, according to one example.

[0070] FIG. 20 is a chart comparing oxygen, nitrogen, sulfur, and heteroatom (TAN) contents of petroleum and biocrude, according to one example.

[0071] FIG. 21 A is a chart illustrating distillation temperature versus percentage distilled of various components of sustainable aviation fuel (SAF), according to one example. [0072] FIG. 2 IB is a chart illustrating the percent mass of hydrocarbons based on carbon number, according to one example.

[0073] FIG. 21C is a chart illustrating SAF properties as compared to jet fuel specification ranges and limits, according to one example.

[0074] FIG. 22 is a graph illustrating relative concentrations of N-containing species in an HTL biocrude feed as determined by comprehensive two-dimensional gas chromatography coupled with mass spectrometry, according to one example.

[0075] FIGS. 23A-23B are graphs of relative concentrations of N-containing species versus species type, according to one example.

[0076] FIG. 24 is a schematic diagram of a hydrothermal liquefaction system and a hydroprocessing system, according to one example.

DETAILED DESCRIPTION

Explanation of Terms

[0077] For purposes of this description, certain aspects, advantages, and novel features of the embodiments of this disclosure are described herein. The disclosed methods, apparatus, and systems should not be construed as being limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The methods, apparatus, and systems are not limited to any specific aspect or feature or combination thereof, nor do the disclosed embodiments require that any one or more specific advantages be present or problems be solved.

[0078] Although the operations of some of the disclosed embodiments are described in a particular, sequential order for convenient presentation, it should be understood that this manner of description encompasses rearrangement, unless a particular ordering is required by specific language set forth below. For example, operations described sequentially may in some cases be rearranged or performed concurrently. Moreover, for the sake of simplicity, the attached figures may not show the various ways in which the disclosed methods can be used in conjunction with other methods.

[0079] As used in this disclosure and in the claims, the singular forms “a,” “an,” and “the” include the plural forms unless the context clearly dictates otherwise. Additionally, the term “includes” means “comprises.” Further, the terms “coupled,” “connected,” and “associated” generally mean electrically, electromagnetically, and/or physically (e.g., mechanically or chemically) coupled or linked and does not exclude the presence of intermediate elements between the coupled or associated items absent specific contrary language.

[0080] In some examples, values, procedures, or apparatus may be referred to as “lowest,” “best,” “minimum,” or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many alternatives can be made, and such selections need not be better, smaller, or otherwise preferable to other selections.

[0081] In the description, certain terms may be used such as “up,” “down,” “upper,” “lower,” “horizontal,” “vertical,” “left,” “right,” and the like. These terms are used, where applicable, to provide some clarity of description when dealing with relative relationships. But these terms are not intended to imply absolute relationships, positions, and/or orientations. For example, with respect to an object, an "upper" surface can become a "lower" surface simply by turning the object over. Nevertheless, it is still the same object.

[0082] As used in this disclosure and in the claims, terms such as “upstream” and “downstream” refer to the relative relationships of certain unit operations and/or components in a process or system, respectively. Unless otherwise indicated, such terms allow for the existence of intervening unit operations or components between corresponding upstream and downstream unit operations or components. Thus, the use of such terms does not require that an “upstream” unit operation and/or equipment be in direct connection with a corresponding “downstream” unit operation and/or component, or vice versa.

[0083] As used in this disclosure and in the claims, terms such as “received from,” “provided to,” and similar terms are used in reference to unit operations or components that receive and provide streams of material, respectively. Such terms allow for the existence of intervening unit operations or components between a unit operation or component that generates a stream (e.g., a “source”) and a unit operation or component in fluid communication with the source that receives the stream (e.g., “a receptacle,” a “sink”). Thus, the use of such terms does not require that streams be directly received from or directly provided to such unit operations or components.

[0084] As used in this disclosure and in the claims, the term “hot oil loop” is interchangably used to refer to a heat transfer liquid circuit. Although the hot oil loop can use oil (e.g., a thermally stable organic liquid such as DOWTHERM™) as the heat transfer liquid, it should be understood that certain examples of the heat transfer liquid circuit can use any liquid to transfer heat to other portions of the heat transfer liquid circuit and such other heat transfer liquids need not be oil-based. [0085] Various schemes, systems, and assemblies disclosed throughout this application comprise various components such as mixing vessels, pumps, heat exchangers, reactors, vapor-liquid disengagement vessels, and valves. It should be understood that any of the examples disclosed herein can include any number of such components in parallel and/or in series, according to the particular requirements of a system. The schemes, systems, and assemblies disclosed herein can additionally or alternatively comprise a plurality of HTL reactors arranged in parallel and/or in series.

[0086] As used in this disclosure and in the claims, the term “steam” refers generally to a gas comprising vaporized water. However, unless otherwise noted, it should be understood that steam can further comprise various non-condensable gases such as carbon dioxide (CO2), oxygen (O2), nitrogen (N2), hydrogen sulfide (H2S), and/or various light hydrocarbons, various condensable gases such as ammonia (NH3) and/or acetic acid, and/or other byproducts of the hydrothermal liquefaction process in addition to vaporized water. As used herein, a “non-condensable gas” is a gas that does not condense from the gas phase to the liquid phase in the temperature and pressure ranges associated with the hydrothermal liquefaction process, for example, temperatures of 32 °F to 800 °F (0 °C to 430 °C) and pressures of 0 psig to 4500 psig (0.1 MPa to 32 MPa).

[0087] Unless otherwise indicated, all numbers expressing quantities of components, pressures, dimensions, forces, moments, molecular weights, percentages, temperatures, times, and so forth, as used in the specification or claims are to be understood as being modified by the term “about.” Accordingly, unless otherwise indicated, implicitly or explicitly, the numerical parameters set forth are approximations that can depend on the desired properties sought and/or limits of detection under test conditions/methods familiar to those of ordinary skill in the art. When directly and explicitly distinguishing embodiments from discussed prior art, the embodiment numbers are not approximations unless the word “about” is recited. Furthermore, not all alternatives recited herein are equivalents.

[0088] Although this application may describe certain components and/or features as associated with certain sizes, dimensions, and/or flow rates, it should be understood that components and/or features can be scaled up or down in accordance with various implementations of the HTL reactor system. The described components can also be rearranged, and/or additional components can be included such as valves, pipes, drains, etc., depending upon the particular application.

[0089] For simplicity and conciseness, this application may not illustrate or describe all the various examples of instrumentation that can be used to measure the operating conditions of the various components (such as tanks, vessels, drums, valves, pumps, reactors, heat exchangers, lines, etc.) described herein. Thus, unless otherwise noted, each component described in this application can be coupled to any combination of level instrumentation, pressure instrumentation, temperature instrumentation, flow rate instrumentation, or any other instrumentation for measuring relevant operating conditions of the disclosed technology. The selected combination of instrumentation may depend on the needs of the particular implementation of the disclosed technology.

Furthermore, any combination of instrumentation may be used to monitor any step or process of the disclosed technology. Finally, it should be understood that the instrumentation can be coupled to one or more controllers for controlling the disclosed technology.

Example 1 : First Representative Hydrothermal Liquefaction Reactor System

[0090] Fouling is a well-known issue of the HTL process. The biological materials found in the feed stream quickly foul hot surfaces. Mineral deposits are another source of fouling, as the feed contains high concentrations of magnesium, calcium, and other metals, as well as carbon dioxide, which precipitate as carbonates at high temperature. As the heat transfer surfaces foul, the heat transfer coefficient is reduced, which results in a loss in energy efficiency or capacity if the equipment is not sufficiently overdesigned. Cleaning the heat exchanger requires taking the equipment offline and disassembly, which is expensive and results in lower capacity utilization. HTL also requires very large heat transfer surface areas due to the high viscosity of the fluid. This highly viscous fluid has laminar flow, which has very poor heat transport properties, resulting in large temperature gradients near the heat transfer surfaces. The large heat transfer areas required result in the heat exchangers being one of the most capital-intensive parts of the HTL process, ft should be noted that the laminar flow resulting in high temperatures near the heat transfer surface also contributes the fouling issues.

[0091] The combination of fouling, resulting in poor equipment reliability, and large heat exchanger surface area, resulting in high equipment costs, is the main obstacle to commercializing the HTL process. HTL requires very high pressures and temperatures for the desired reactions to occur. Coincident high design temperature and pressure requires extremely thick metal for equipment design. Lowering the pressure where heat transfer occurs can lower equipment cost. In the system shown in FIG. 2, the heat transfer process is split into two or more pressure zones (see FIG. 2), so a significant portion of the heat transfer can occur at lower pressure and the heat exchangers in the low pressure zone can be constructed at lower cost. Although this design can be an improvement over the historical HTL design (FIG. 1), it can still be susceptible to fouling and the low pressure heat exchangers may need to be taken offline for cleaning depending on the feed materials used. [0092] Certain HTL systems disclosed in this application overcome the issues described above by transferring heat with steam, as opposed to a hot surface (heat exchanger). Steam is injected directly into the colder feed and the steam condenses to a liquid and releases latent heat to warm the feed. Heat transfer does not occur across a surface boundary, so surface fouling cannot occur. The heat transfer is also independent of a surface area, so the equipment can be much cheaper because less metal is required. The steam injection can occur in a pipe or drum with relatively simple vessel internals, as illustrated in FIG. 4. This disclosure describes a process for recovering heat from a high temperature reactor effluent without the use of heat exchangers as a part of a hydrothermal liquefaction process. While a specific embodiment is described it is to be understood that this description is merely exemplary and can be variously embodied based upon the needs of a particular user.

[0093] In one example, the reactor product is approximately 650 °F (344 °C) and 2,600 psig (18 MPa). Flash steam will be formed if the pressure is suddenly reduced adiabatically. A simple pressure letdown valve can be used to reduce the pressure, followed by a separation drum to separate the steam from the remaining liquid product. The flash steam can be routed to an earlier stage of the process to heat the reactor feed stream. The flash steam can be mixed with the cold feed through an inline mixer or a mixing drum, as shown in the attached figures. To maximize heat recovery, the pressure letdown can be performed in multiple stages to provide heating at multiple temperatures and pressures. Through a staged pressure letdown process, higher steam temperatures can be achieved, while still recovering the maximum amount of lower temperature heat. Multiple stage letdown is also less erosive to the pressure letdown equipment, so longer life and better reliability can be expected. The flash steam will leave the oil “biocrude” product behind, limiting recycle of the oil stream. The majority of the organics from the aqueous stream will not flash, however, a substantial portion of the CO2, H2S, ammonia, and other light products will be stripped from the reactor effluent. Some of the major advantages of this novel process configuration may include reduced capital costs, reduced maintenance of equipment and equipment cleaning frequency (due to fouling), and improved operability.

[0094] FIG. 1 shows a traditional HTL processing scheme, where heat recovery is conducted at one pressure level. An adaptation of the traditional HTL process, where heat is recovered at two pressure stages is shown in FIG. 2. FIG. 3 illustrates a HTL reactor system where the heat recovery of the low-pressure heat exchangers are replaced by flash steam heating. Note that the flash steam heating in this example is performed in two stages, which could be more (3-stage, 4-stage, etc.) or just a single stage in application. At lower feed temperatures, an extremely high fluid viscosity (>10,000 cP (>10 Pa-s)) might necessitate active mixing (also illustrated on the left side of Figure 4), but this equipment can be relatively simple and low cost. Once the stream is partially heated, the viscosity is lowered significantly, and a static mixer can be used to mix the steam and feed. Mixing steam and cold feed can also occur in a drum with steam injected near the bottom. The mixing drum would require relatively few internals, aside from sufficient piping to ensure good steam distribution. Turbulence provided by the steam would help mix the drum and help prevent solids from accumulating in the bottoms or at the vessel walls.

[0095] The heat exchanger surface is reduced significantly, so extra capacity can be built to allow for scheduled cleaning and maintenance. The size of the steam heating vessels, the chosen target temperatures and the size of the piping between the vessels may be modified to extend or reduce the residence times at various temperature points to reduce the viscosity, control the rheology, improve yields or reduce fouling in the subsequent heat exchanger (FIG. 3).

[0096] All HTL heat recovery approaches that the inventors are aware of require some form of heat exchanger to heat the feed to reactor temperature and recovery heat from the reactor effluent. Because HTL has yet to be deployed at commercial scale, all demonstrations have been relatively small and utilized annular or “double-pipe” heat exchanger designs. Annular heat exchangers might struggle to scale to full commercial size and traditional shell-and-tube heat exchanger designs have been proposed. Spiral heat exchangers are being explored for HTL to help improve reliability over shell-and-tube designs in high fouling service, but spiral heat exchangers might still experience some fouling on the hot heat transfer surface and require periodic cleaning. The systems and methods described herein presents a process design for heat integration that can be more reliable and require less continual maintenance than traditional heat exchanger designs. The systems and methods described herein also have the potential to lower capital costs because less metal is required to achieve an equivalent amount of heat transfer.

[0097] Additional advantages and novel features of the disclosed technology will be set forth as follows and will be readily apparent from the descriptions and demonstrations set forth herein. Accordingly, the following descriptions of the disclosed technology should be seen as illustrative and not as limiting in any way.

[0098] Now referring back to FIG. 1, FIG. 1 is a schematic diagram of a traditional HTL reactor system 100 according to one example, where heat recovery is conducted at one pressure level. The HTL reactor system 100 comprises an aqueous slurry source 102 configured to provide an aqueous slurry stream. The aqueous slurry stream comprises biosolids. In certain examples, the biosolids content (measured as % dry mass) of the aqueous slurry stream can be from 5% to 45%, such as from 15% to 35%, 10% to 30%, 20% to 30%, or 25%. [0099] The HTL reactor system 100 further comprises a pump 120 disposed downstream of the aqueous slurry source 102. The pump 120 is configured to pressurize the aqueous slurry stream received from the aqueous slurry source 102. In certain embodiments, the pump 120 can pressurize the aqueous slurry to a pressure of 2,400 psig to 2,800 psig (16 MPa to 20 MPa), such as a pressure of 2,500 psig to 2,700 psig (17 MPa to 19 MPa), 2,550 psig to 2,650 psig (17 MPa-19 MPa), or 2,600 psig (18 MPa).

[0100] The HTL reactor system 100 further comprises a heat exchanger 130 disposed downstream of the pump 120. The heat exchanger 130 is configured to receive an aqueous slurry stream from the pump 120. In certain embodiments, the temperature of the aqueous slurry stream received from the pump 120 can be from 50 °F to 110 °F (10 °C to 45 °C), such as from 65 °F to 95 °F (15 °C to 35 °C) or 80 °F (27 °C). The heat exchanger 130 is configured to heat the aqueous slurry stream received from the pump 120. In certain embodiments, the heat exchanger 130 can heat the aqueous slurry stream received from the pump 120 to a temperature of 460 °F to 660 °F (235 °C to 350 °C), such as a temperature of 510 °F to 610 °F (265 °C to 325 °C) or 560 °F (294 °C). In certain embodiments, the pressure of the heated aqueous slurry stream exiting the heat exchanger 130 can be from 2,450 psig to 2,650 psig (17 MPa to 19 MPa), such as from 2,500 psig to 2,600 psig (17 MPa to 18 MPa) or at 2,550 psig (18 MPa).

[0101] The HTL reactor system 100 further comprises a heater 140 disposed downstream of the heat exchanger 130. The heater 140 can be configured to heat an aqueous slurry stream received from the heat exchanger 130. In certain embodiments, the heater 140 can heat the aqueous slurry stream received from the heat exchanger 130 to a temperature of 500 °F to 750 °F (260 °C to 399 °C), such as a temperature of 550 °F to 750 °F (285 °C to 400 °C), 600 °F to 700 °F (315 °C to 375 °C), or 650 °F (345 °C). In certain embodiments, the pressure of the heated aqueous slurry stream exiting the heater 140 can be from 1,000 psig to 4,000 psig (7 MPa to 28 MPa), such as from 1,500 psig-3,500 psig (10 MPa-25 MPa), 2,000 psig-3,000 psig (13 MPa to 21 MPa), 2,500 psig to 3,200 psig (17 MPa to 22 MPa), 3,000 psig to 3,200 psig (20 MPa to 22 MPa), 3,100 psig to 3,200 psig (21 MP to 22 MPa), or at 2,500 psig (17 MPa).

[0102] The HTL reactor system 100 further comprises a reactor 160 disposed downstream of the heater 140. The reactor 160 is configured to receive an aqueous slurry stream from the heater 140 and produce a product steam which subsequently exits the reactor 160.

[0103] The heat exchanger 130 is further configured to receive the product stream from the reactor 160. In certain embodiments, the temperature of the product stream received from the reactor 160 can be from 500 °F to 750 °F (260 °C to 400 °C), such as from 550 °F to 750 °F (285 °C to 400 °C), 600 °F to 700 °F (315 °C to 375 °C), or at 650 °F (343 °C). In certain embodiments, the pressure of the product stream received from the reactor 160 can be from 1,000 psig to 4,000 psig (7 MPa to 28 MPa), such as from 1,500 psig to 3,500 psig (10 MPa to 25 MPa), 2,000 psig to 3,000 psig (13 MPa to 21 MPa), or at 2,500 psig (17 MPa). The heat exchanger 130 is further configured to cool the product stream. In certain embodiments, the heat exchanger 130 can be configured to cool the product stream received from the heat exchanger 130 to a temperature of 150 °F to 250 °F (65 °C to 125 °C), such as a temperature of 175 °F to 225 °F (75 °C to 110 °C) or 200 °F (93 °C). In certain embodiments, the pressure of the cooled product stream leaving the heat exchanger 1 0 can be from 2,100 psig to 2,700 psig (14 MPa to 19 MPa), such as from 2,200 to 2,600 psig (15 MPa to 18 MPa), 2,300 psig to 2,500 psig (16 MPa to 18 MPa), or at 2,400 psig (17 MPa).

[0104] The HTL reactor system 100 further comprises a valve 170 disposed downstream of the heat exchanger 130. The valve 170 is configured to receive a product stream from the heat exchanger 130.

[0105] The HTL reactor system 100 further comprises a cooler 180 configured to receive a product stream from the valve 170.

[0106] The HTL reactor system 100 further comprises a raw product storage 196 configured to receive a product stream from the cooler 180.

[0107] An adaptation of the traditional HTL process, where heat is recovered at two pressure stages, is shown in FIG. 2. A two-pressure stage HTL reactor system 200 comprises the aqueous slurry source 102 configured to provide an aqueous slurry stream comprising biosolids. In certain embodiments, the aqueous slurry stream can comprise 5% to 45% biosolids by percent dry mass, such as 15% to 35% biosolids, 20% to 30% biosolids, 10% to 30% biosolids, or 25% biosolids. In certain embodiments, the initial temperature of the aqueous slurry stream as the aqueous stream exits the aqueous slurry source 102 can be from 50 °F to 110 °F (10 °C to 44 °C), such as from 65 °F to 95 °F (15 °C to 35 °C) or 80 °F (27 °C). In certain embodiments, the pressure of the aqueous slurry stream can be from 0 psig to 20 psig (0 MPa to 1 MPa), such as from 0 psig to 15 psig (0 MPa to 1 MPa) or 0 psig to 10 psig (0 MPa to 1 MPa).

[0108] The HTL reactor system 200 further comprises a first pump 220 disposed downstream of the aqueous slurry source 102. The first pump 220 is configured to pressurize the aqueous slurry stream received from the aqueous slurry source 102. In certain embodiments, the first pump 220 can pressurize the aqueous slurry stream received from the aqueous slurry source 102 to a pressure of 600 psig to 1,400 psig (4 MPa to 10 MPa), such as to a pressure of 800 psig to 1,200 psig (5 MPa to 9 MPa), 900 psig to 1,100 psig (6 MPa to 8 MPa), or 1,000 psig (7 MPa). [0109] The HTL reactor system 200 further comprises a first heat exchanger 210 disposed downstream of the first pump 220. The first heat exchanger 210 is configured to heat an aqueous slurry stream received from the pump 220 to 300 °F to 600 °F (145 °C to 320 °C).

[0110] The HTL reactor system 200 further comprises a second pump 240 disposed downstream of the first heat exchanger 210. In certain embodiments, the second pump 240 can be configured to pressurize an aqueous slurry stream received from the first heat exchanger 210 to a pressure of 2,400 psig to 3,500 psig (16 MPa to 20 MPa), such as to a pressure of 2,500 psig to 3,200 psig (17 MPa to 22 MPa), 3,000 psig to 3,200 psig (20 MPa to 22 MPa), 3,100 psig to 3,200 psig (21 MP to 22 MPa), 2,500 psig to 2,700 psig (17 MPa to 19 MPa), 2,550 psig to 2,650 psig (17 MPa to 19 MPa), or 2,600 psig (18 MPa).

[0111] The HTL reactor system 200 further comprises a second heat exchanger 230 disposed downstream of the second pump 240. The second heat exchanger 230 is configured to heat an aqueous slurry stream received from the second pump 240. In certain embodiments, the second heat exchanger 230 can be configured to heat the aqueous slurry stream received from the second pump 240 to a temperature of 540 °F to 740 °F (280 °C to 395 °C), such as to a temperature of 590 °F to 690 °F (310 °C to 370 °C) or 640 °F (338 °C).

[0112] The HTL reactor system 200 further comprises a heat transfer liquid circuit 250 formed by the first heat exchanger 210 (e.g., the shell side of the heat exchanger 210), the second heat exchanger 230 (e.g., the shell side of the heat exchanger 230), a third heat exchanger 280 (e.g., the tube side of the heat exchanger 280), a heat transfer liquid reservoir 256, and an heat transfer liquid heater 258. The second heat exchanger 230 is disposed downstream of the heat transfer liquid heater 258 and is configured to receive a heat transfer liquid stream from the heat transfer liquid heater 258. The first heat exchanger 210 is disposed downstream of the second heat exchanger 230 and is configured to receive a heat transfer liquid stream from the second heat exchanger 230. The third heat exchanger 280 is disposed downstream of the first heat exchanger 210 and is configured to receive a heat transfer liquid stream from the first heat exchanger 210. In the illustrated example, a heat transfer liquid reservoir 256 is disposed downstream of the third heat exchanger 280 and is configured to receive a heat transfer liquid stream from the third heat exchanger 280. However, in certain examples, the heat transfer liquid reservoir 256 can instead be disposed upstream of the third heat exchanger 280. The heat transfer liquid heater 258 is disposed downstream of the heat transfer liquid reservoir 256 and is configured to receive a heat transfer liquid stream from the heat transfer liquid reservoir 256. [0113] The HTL reactor system 200 further comprises the reactor 160 disposed downstream of the second heat exchanger 230. The reactor 160 is configured to convert an aqueous slurry stream received from the second heat exchanger 230 to a product stream. The third heat exchanger 280 is disposed downstream of the reactor 160 and is configured to receive the product stream from the reactor 160.

[0114] The HTL reactor system 200 further comprises a valve 270 disposed downstream of the third heat exchanger 280. The valve 270 is configured to receive a product stream from the third heat exchanger 280 (e.g., to reduce the pressure of the product stream).

[0115] The HTL reactor system 200 further comprises the raw product storage 196 configured to receive a product stream from the valve 270.

[0116] The HTL reactor system 200 illustrated in FIG. 2 and other exemplary systems are further described in U.S. Patent No. 11,279,882 and U.S. Patent Application No. 18/352,551, filed July 14, 2023, which are incorporated by reference herein in their entirety.

Example 2: Second Representative Hydrothermal Liquefaction Reactor System

[0117] As noted above, fouling can be an issue in HTL systems.

[0118] FIG. 3 illustrates a HTL reactor system 300 where the heat recovery of the low-pressure heat exchangers of FIGS. 1-2 are replaced by a flash steam heat recovery system that addresses at least some of the fouling issues in existing systems. Note that the flash steam heating in this example is performed in two stages, which could be more (3-stage, 4-stage, etc.) or just a single stage in application.

[0119] The HTL reactor system 300 can comprise the aqueous slurry source 102, which can be configured to provide an aqueous slurry stream 304. In certain embodiments, the pressure of the aqueous slurry stream 304 supplied from the source 102 can be from 0 psig to 50 psig (0 MPa to 0.5 MPa), such as from 5 psig to 15 psig (0 MPa to 0.3 MPa) or 10 psig (0.2 MPa). In certain embodiments, the aqueous slurry stream 304 can comprise (as a % dry mass) 5% to 45% biosolids, such as 15% to 35% biosolids, 10% to 30% biosolids, 20% to 30% biosolids, or 25% biosolids.

[0120] The HTL reactor system 300 can further comprise a first mixing vessel 310 disposed downstream of the aqueous slurry source 102. The first mixing vessel 310 can be configured to mix the aqueous slurry stream 304 received from the aqueous slurry source 102 with a first vaporized water and gas byproducts stream 314 (which is also referred to herein as a “first gas stream” and/or a “first steam stream”). In certain embodiments, mixing the aqueous slurry stream 304 received from the aqueous slurry source 102 with the first vaporized water and gas byproduct stream 314 in the first mixing vessel 310 can heat the resulting mixture to a temperature of, for example, 150 °F to 350 °F (65 °C to 180 °C), such as 170° F to 270 °F (75 °C to 135 °C), 195° F to 245° F (90 °C to 120 °C) or 220° F (105 °C).

[0121] The HTL reactor system 300 can further comprise a first pump 320 disposed downstream of the first mixing vessel 310. The first pump 320 can be configured to receive an aqueous slurry stream 322 from the first mixing vessel 310 and pressurize the aqueous slurry stream 322 received from the first mixing vessel 310. In certain embodiments, the first pump 320 can pressurize the aqueous slurry stream 322 received from the aqueous slurry source 102 to a pressure of 50 psig to 350 psig (0.4 MPa to 2.6 MPa), such as a pressure of 90 psig to 290 psig (0.5 MPa to 3 MPa), 140 psig to 240 psig (1 MPa to 2 MPa) or 190 psig (1 MPa). In certain examples, the first pump 320 can further be configured to mix the aqueous slurry. However, in other examples, the HTL reactor system 300 can further comprise a mixer for mixing the aqueous slurry.

[0122] The HTL reactor system 300 can further comprise a second mixing vessel 330 disposed downstream of the first pump 320. The second mixing vessel 330 can be configured to mix an aqueous slurry stream 324 received from the first pump 320 with a second vaporized water and gas byproducts stream 334 (which is also referred to herein as a “first gas stream” and/or a “first steam stream”). In certain embodiments, the viscosity of the aqueous slurry stream 324 received from the first pump 320 can be from 1,000 cP to 3,000 cP (1 Pa-s to 3 Pa-s), such as from 1,500 cP to 2,500 cP (1.5 Pa- s to 2.5 Pa-s) or at 2,000 cP (2 Pa-s). In certain embodiments, mixing the aqueous slurry stream 324 received from the first pump 220 with the second vaporized water and gas byproducts stream 334 heats the resulting mixture to a temperature of 200° F to 400° F (90 °C to 205 °C), such as 270 °F to 370 °F (130 °C to 190 °C), 300 °F to 340 °F (145 °C to 175 °C), 310 °F to 330 °F (150 °C to 170 °C), or 320 °F (160 °C).

[0123] The HTL reactor system 300 can further comprise a second pump 340 disposed downstream of the second mixing vessel 330. The second pump 340 can be configured to pressurize an aqueous slurry stream 342 received from the second mixing vessel 330. In certain embodiments, the viscosity of the aqueous slurry stream 342 received from the second mixing vessel 330 can be from 100 cP to 700 cP (0.1 Pa-s to 0.7 Pa- s), such as from 200 cP to 600 cP (0.2 Pa- s to 0.6 Pa-s), 300 cP to 500 cP (0.3 Pa-s to 0.5 Pa- s), or at 400 cP (0.4 Pa-s).

[0124] In certain examples, the HTL reactor system 300 can further comprise a heat transfer liquid circuit 350 (which can also be referred to as a “hot oil loop”). Although certain examples of the heat transfer liquid circuit 350 can comprise an oil as the heat transfer liquid, it should be understood that the heat transfer liquid can contain any liquid and need not be oil-based. In the illustrated example, the heat transfer liquid circuit 350 comprises a first heat transfer liquid heat exchanger 352, a second heat transfer liquid heat exchanger 354, a heat transfer liquid reservoir 356, and a heat transfer liquid heater 358. The first heat transfer liquid heat exchanger 352 can comprise a portion (referred to generally as the “cold side”) configured to receive the liquid stream to be heated, and a portion (referred to generally as the “hot side”) configured to receive a hot heat transfer liquid stream to exchange heat with the liquid stream to be heated on the cold side. In examples in which the first heat transfer liquid heat exchanger 352 is configured as a shell and tube heat exchanger, the tubes can form the “cold side” (also referred to as the "tube side") and the shell can form the “hot side” (also referred to as the “shell side”). The first heat transfer liquid heat exchanger 352 can be configured to receive an aqueous slurry stream 344 from the second pump 340 (e.g., on the cold side). The second heat transfer liquid heat exchanger 354 can include a hot side and a cold side similar to the first heat transfer liquid heat exchanger 352 and can be configured to receive a heat transfer liquid stream 353 from the first heat transfer liquid heat exchanger 352 (e.g., on the cold side). The heat transfer liquid reservoir 356 can be configured to receive a heat transfer liquid stream 355 from the second heat transfer liquid heat exchanger 354. The heat transfer liquid heater 358 can be configured to receive a heat transfer liquid stream 357 from the heat transfer liquid reservoir 356. The first heat transfer liquid heat exchanger 352 can be configured to receive a heat transfer liquid stream 359 from the heat transfer liquid heater 358 (e.g., on the hot side). Thus, heat transfer liquid circulating in the heat transfer liquid circuit 350 can flow from the cold side of the second heat transfer liquid heat exchanger 354 to the heat transfer liquid reservoir 356, through the heat transfer liquid heater 358 to the hot side of the first heat transfer liquid heater 352 and back to the cold side of the second heat transfer liquid heat exchanger 354.

[0125] The HTL reactor system 300 can further comprise the reactor 160 disposed downstream of the first heat transfer liquid heat exchanger 352. The reactor 160 can be configured to receive an aqueous slurry stream 362 from the first heat transfer liquid heat exchanger 352.

[0126] The second heat transfer liquid heat exchanger 354 can be disposed downstream of the reactor 160 and can be configured to receive a product stream 364 produced by the reactor 160 (e.g., on the hot side of the second heat transfer liquid heat exchanger 354).

[0127] In certain examples, the HTL reactor system 300 can comprise a heat exchanger instead of the heat transfer liquid circuit 350, wherein the aqueous slurry stream 344 flows through the cold side of the heat exchanger and the product stream 364 flows through the hot side of the heat exchanger. [0128] The HTL reactor system 300 can further comprise a first valve 370 disposed downstream of the second heat transfer liquid heat exchanger 354. The first valve 370 can be a pressure letdown valve configured to reduce the pressure of a product stream 371 received from the second heat transfer liquid heat exchanger 354. In certain embodiments, the first valve 370 can reduce the pressure of the product stream 371 received from the second heat transfer liquid heat exchanger 354 to a pressure of 100 psig to 300 psig (0 MPa to 3 MPa), such as a pressure of 150 psig to 250 psig (1 MPa to 2 MPa), 175 psig to 225 psig (1 MPa to 2 MPa), or 200 psig (1.5 MPa).

[0129] In certain examples, the first valve 370 can be configured to control the back pressure of the HTL reactor system 300, while the second pump 340 can be configured to control the flow rate of the HTL reactor system 300. However, in other examples, the second pump 340 can be configured to control the pressure of the HTL reactor system 300, while the first valve 370 can be configured to control the flow rate of the HTL reactor system. Although specific configurations of the second pump 340 and the first valve 370 can be used for specific implementations of the HTL reactor system 300, it should be understood that any suitable configuration of the second pump 340, the first valve 370, and/or other components can generally be used to control the pressure and flow rate of the HTL reactor system 300 or any other HTL reactor system disclosed in this application.

[0130] The HTL reactor system 300 can further comprise a first vapor- liquid disengagement vessel 380 disposed downstream of the first valve 370. The first vapor-liquid disengagement vessel 380 can be configured to form the second vaporized water and gas byproducts stream 334 from a product stream 373 received from the first valve 370. The second mixing vessel 330 can be configured to receive the second vaporized water and gas byproducts stream 334 from the first vapor-liquid disengagement vessel 380. In certain embodiments, the temperature of the second vaporized water and gas byproducts stream 334 can be from 250° F to 550° F (120 °C to 290 °C), such as 320 °F to 420 °F (160 °C to 220 °C) 345 °F to 395 °F (170 °C to 205 °C) or at 370 °F (188 °C).

[0131] The HTL reactor system 300 can further comprise a second valve 374 disposed downstream of the first vapor-liquid disengagement vessel 380. The second valve 374 can be a pressure let-down valve configured to reduce the pressure of a product stream 375 received from the first vapor-liquid disengagement vessel 380. In certain embodiments, the second valve 374 can reduce the pressure of the product stream 375 received from the first vapor-liquid disengagement vessel 380 to a pressure of 5 psig to 100 psig (0.1 MPa to 0.8 MPa), such as 10 psig to 100 psig (0.1 MPa to 0.8 MPa), 10 psig to 50 psig (0.2 MPa to 0.4 MPa), 20 psig to 40 psig (0.2 MPa to 0.4 MPa), 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or 30 psig (0.3 MPa).

[0132] The HTL reactor system 300 can further comprise a second vapor-liquid disengagement vessel 390 disposed downstream of the second valve 374. The second vapor-liquid disengagement vessel 390 can be configured to form the first vaporized water and gas byproducts stream 314 from a product stream 377 received from the second valve 374. In certain examples, the temperature of the first vaporized water and gas byproducts stream 314 can be from 150 °F to 400 °F (65 °C to 205 °C), such as 210 °F to 310 °F (95 °C to 155 °C), 235 °F to 285 °F (110 °C to 145 °C) or at 260 °F (127 °C).

[0133] The HTL reactor system 300 can further comprise the raw product storage 196 configured to receive a product stream 394 from the second vapor-liquid disengagement vessel 390. However, in certain examples, the product stream 394 can instead pass directly to a downstream processing unit without entering an intermediate storage.

[0134] At lower feed temperatures, an extremely high fluid viscosity (>10,000 cP (>10 Pa s)) might necessitate active mixing equipment (further illustrated in FIG. 4). For example, once the first stream is partially heated, the viscosity is lowered significantly and a static mixer can be used to mix the first vaporized water and gas byproducts stream 314 and the aqueous slurry stream 304 received from the aqueous slurry source 102. Such mixing can also occur in a mixing drum with steam injected near the bottom. The mixing drum would require relatively few internals, aside from sufficient piping to ensure good steam distribution. Turbulence provided by the streams (e.g., the first stream and/or the second stream) would help mix the contents of the mixing drum and help prevent solids from accumulating in the bottoms or at the mixing drum’s walls.

[0135] In the HTL reactor system 300, heat exchanger surface is reduced significantly, so extra capacity can be built to allow for scheduled cleaning and maintenance. The size of the mixing vessels, the chosen target temperatures, and the size of the piping between the mixing vessels may be modified to extend or reduce the residence times at various temperature points to reduce the viscosity, control the rheology, improve yields, or reduce fouling in subsequent heat exchangers (such as the heat exchangers 352, 354 comprising the heat transfer liquid circuit 350).

[0136] Certain examples of HTL heat recovery approaches require some form of heat exchanger to heat the feed to reactor temperature and recovery heat from the reactor effluent. Because HTL has yet to be deployed at commercial scale, all demonstrations have been relatively small and utilized annular or “double-pipe” heat exchanger designs. The disclosed HTL reactor systems (such as

HTL reactor system 300) present a process design for heat integration that can be more reliable and require less continual maintenance than traditional heat exchanger designs. Such schemes also have the potential to lower capital costs, especially as HTL is deployed at commercial scale, because less metal is required to achieve an equivalent amount of heat transfer.

[0137] FIG. 4 is a side view of a low pressure section of a HTL reactor system 400, according to one example. The component arrangement, component sizes and performance ratings, temperatures, pressures, dimensions, flow rates, etc., in the description of the system 400 are provided as examples of a representative system configuration and can be varied depending on size, throughput, etc. The HTL reactor system 400 can first comprise a source or reservoir configured as a cake hopper 402 and a dewatered feed pump 404 coupled to an output of the cake hopper 402. The dewatered feed pump 404 can be a progressive cavity pump. The dewatered feed pump 404 can comprise a driver comprising a motor with a variable frequency drive (which is also referred to herein as a “VFD”). Feed can exit the dewatered feed pump 404. In certain embodiments, the temperature of the feed can be from 40 °F to 200 °F (0 °C to 95 °C), such as from 61 °F to 101 °F (16 °C to 39 °C), 71 °F to 91 °F (21 °C to 33 °C) or at 81 °F (27 °C). In certain embodiments, the pressure of the feed can be from 50 psig to 90 psig (0.4 MPa to 0.7 MPa), such as from 60 psig to 80 psig (0.5 MPa to 0.7 MPa) or at 70 psig (0.6 MPa). In certain examples, a mass flow rate of the feed can be 28.3 klb/h (12,830 kg/h) and a volumetric flow rate of the feed can be 28.5 gpm (108 L/m). In certain embodiments, the viscosity of the feed can be from 8,000 cP to 28,000 cP (8 Pa- s to 28 Pa-s), such as from 13,000 cP to 23,000 cP (13 Pa- s to 23 Pa- s) or at 18,000 cP (18 Pa- s). In certain embodiments, the cake hopper 402 and the dewatered feed pump 404 can be disposed inside a building 403.

[0138] A first pipe 405 can connect the dewatered feed pump 404 and a dynamic mixer 406 disposed downstream of the dewatered feed pump 404. In certain embodiments, the pressure of the feed flowing through the first pipe 405 can be from 30 psig to 80 psig (0.3 MPa to 0.7 MPa), such as from 40 pisg to 60 psig (0.4 MPa to 0.7 MPa) or at 50 psig (0.4 MPa).

[0139] The dynamic mixer 406 can comprise one or more (such as three) inlets 407 for accepting steam. In certain embodiments, the mass flow rate of steam through the one or more inlets 407 can be 1.2 klb/h (544 kg/h). In certain embodiments, the dynamic mixer 406 can comprise a motor.

[0140] A second pipe 408 can connect the dynamic mixer 406 and a low-pressure steam heating vessel 410 disposed downstream of the dynamic mixer 406. In certain embodiments, the temperature of the stream flowing through the second pipe 408 can be from 145 °F to 185 °F (60 °C to 85 °C), such as from 155 °F to 175 °F (65 °C to 80 °C) or at 165 °F (75 °C). In certain embodiments, the pressure of the stream flowing through the second pipe 408 can be from 5 psig to 25 psig (0.1 MPa to 0.3 MPa), such as from 10 psig to 20 psig (0.2 MPa to 0.2 MPa) or at 15 psig (0.2 MPa). In certain embodiments, the viscosity of the stream flowing through the second pipe 408 can be from 3,200 cP to 7,200 cP (3.2 Pa- s to 7.2 Pa- s), such as from 4,200 cP to 6,200 cP (4.2 Pa- s to 6.2 Pa-s) or at 5,200 cP (5.2 Pa-s).

[0141] Steam can be injected into the low-pressure steam heating vessel 410 through one or more inlets 412 disposed at a bottom portion of the low-pressure steam heating vessel 410 at, for example, a mass flow rate of 1.2 klb/h (544.3 kg/h). In certain embodiments, the pressure of the steam can be from 20 psig to 40 psig (0.2 MPa-0.4 MPa), such as from 25 psig to 35 psig (0.3 MPa to 0.3 MPa) or at 30 psig (0.3 MPa). In certain embodiments, the contents of the low-pressure steam heating vessel 410 can be held at a pressure of 0 psig to 20 psig (0.1 MPa to 0.2 MPa), such as a pressure of 5 psig to 15 psig (0.1 MPa-0.2 MPa) or 10 psig (0.2 MPa). In certain embodiments, the contents can be held under pressure for 5 minutes to 100 minutes, such as for 5 minutes to 15 minutes, 7.5 minutes to 12.5 minutes, 20 minutes to 90 minutes, 45 minutes to 75 minutes, or 60 minutes.

[0142] A third pipe 414 can connect the low-pressure steam heating vessel 410 and a low-pressure feed pump 420 disposed downstream of the low-pressure steam heating vessel 410.

[0143] In certain embodiments, the low-pressure feed pump 420 can be a progressive cavity pump. The low-pressure feed pump 420 can comprise a driver comprising a 25 HP (18.6 kW) motor with a variable frequency drive (VFD). In certain embodiments, feed can leave the low-pressure feed pump 420 at a temperature of 175 °F to 275 °F (75 °C to 135 °C), such as a temperature of 200 °F to 250 °F (90 °C to 125 °C) or 225 °F (107 °C). In certain embodiments, the pressure of the feed leaving the low-pressure feed pump 420 can be from 200 psig to 300 psig (1.5 MPa to 2.2 MPa), such as from 225 psig to 275 psig (1.7 MPa to 2.0 MPa), or at 250 psig (1.8 MPa). In certain embodiments, the viscosity of the feed leaving the low-pressure feed pump 420 can be from 1,000 cP to 3,000 cP (1 Pa-s to 3 Pa-s), such as from 1,500 cP to 2,500 cP (1.5 Pa-s to 2.5 Pa- s) or at 2,000 cP (2 Pa- s).

[0144] A fourth pipe 422 can connect the low-pressure feed pump 420 and a static mixer 424 disposed downstream of the low-pressure feed pump 420.

[0145] The static mixer 424 can comprise one or more (such as four) inlets 426 configured to accept steam and/or offgas. In certain embodiments, the flow of steam and/or offgas through the one or more inlets 426 can be 1.5 klb/h (680 kg/h). In certain embodiments, the pressure of the contents of the static mixer 424 can be from 20 psig to 60 psig (0.2 MPa to 0.5 MPa), such as from 30 psig to 50 psig (0.3 MPa to 0.4 MPa) or at 40 psig (0.4 MPa). [0146] The HTL reactor system 400 can further comprise a high-pressure steam heating vessel 430 disposed downstream of the static mixer 424. In certain embodiments, feed can enter the high- pressure steam heating vessel 430 through a tangential entry inlet 432 disposed at an intermediate portion of the high-pressure steam heating vessel 430. The temperature of the feed can be from 230 °F to 330 °F (125 °C to 150 °C), such as from 255 °F to 305 °F (130 °C to 145 °C) or at 280 °F (138 °C). In certain embodiments, the pressure of the feed entering the high-pressure steam heating vessel 430 can be from 160 psig to 260 psig (1.2 MPa to 1.9 MPa), such as from 185 psig to 235 psig (1 .4 MPa to 1 .7 MPa) or at 210 psig (1 .6 MPa). In certain embodiments, feed can enter the high-pressure steam heating vessel 430 at a viscosity from 500 cP to 900 cP (0.5 Pa-s to 0.9 Pa-s), such as from 600 cP to 800 cP (0.6 Pa- s to 0.8 Pa- s) or at 700 cP (0.7 Pa- s). Steam and/or offgas can enter the high-pressure steam heating vessel 430 through one or more (such as four) inlets 434 disposed at a bottom portion of the high-pressure steam heating vessel 430. In certain embodiments, the pressure of steam and/or offgas entering the inlets 434 can be from 190 psig to 290 psig (1.4 MPa to 2.1 MPa), such as from 215 psig to 265 psig (1.6 MPa to 1.9 MPa) or at 240 psig (1.8 MPa). In certain embodiments, steam can enter the inlets 434 at a mass flow rate of 1.5 klb/h (680.4 kg/h). In certain embodiments, the contents of the high-pressure steam heating vessel 430 can be held at a pressure of 150 psig to 250 psig (1.1 MPa to 1.8 MPa), such as a pressure of 175 psig to 225 psig (1.3 MPa to 1.7 MPa) or 200 psig (1.5 MPa). In certain examples, the contents of the high-pressure steam heating vessel 430 can be held under pressure for 5 to 30 minutes, such as for 10 to 30 minutes, 15 minutes to 25 minutes, 5 minutes to 15 minutes, 7.5 minutes to 12.5 minutes, or for 10 minutes.

[0147] A fifth pipe 436 can connect the high-pressure steam heating vessel 430 and a high- pressure feed pump 440 disposed downstream of the high-pressure steam heating vessel 430.

[0148] In certain embodiments, the high-pressure feed pump 440 can comprise a multi-stage centrifugal pump. In other embodiments, the high-pressure feed pump 440 can comprise a positive displacement pump. The high-pressure feed pump 440 can comprise a motor with a variable flow drive (VFD).

[0149] A sixth pipe 442 can connect the high-pressure feed pump 440 with a high-pressure HTL reactor section.

[0150] The HTL reactor system 400 can comprise an offgas collection header 444, which can be above the low-pressure steam heating vessel 410 and the high-pressure steam heating vessel 430. In certain embodiments, offgas can flow through the offgas collection header 444 at a mass flow rate of 1.1 klb/h (500 kg/h). In certain embodiments, the temperature of the offgas can be from 230 °F to 310 °F (110 °C to 155 °C), such as from 250 °F to 290 °F (120 °C to 145 °C) or at 270 °F (132 °C). In certain embodiments, the pressure of the offgas can be from 3 psig to 13 psig (0.1 MPa to 0.2 MPa), such as at 8 psig (0.2 MPa).

[0151] A seventh pipe 446 can connect the low-pressure steam heating vessel 410 and the offgas collection header 444 disposed downstream of the low-pressure steam heating vessel 410. In certain embodiments, a gas stream flowing through the seventh pipe 446 can comprise 40% to 80%, H2O, such as 50% to 70% H2O or 60% H2O. In certain embodiments, the gas stream can comprise 15% to 55% CO ₂ , such as 25% to 45% CO ₂ , 15% to 35% CO ₂ , 20% to 30% CO ₂ , 30% to 40% CO2, or 35% CO2. In certain embodiments, the stream can comprise 1.5% to 5.5% H2S, such as 2.5% to 4.5% H2S or 3.5% H2S. In certain embodiments, the gas stream can comprise 0.5% to 3% NH3, such as 1% to 2% NH3 or 1.5% NH3. In certain embodiments, the gas stream can comprise 0% to 1% hydrocarbons, such as 0.5% hydrocarbons. In certain embodiments, the gas stream can flow through the seventh pipe 446 at a mass flow rate of 250 Ib/h (113.4 kg/h).

[0152] An eighth pipe 448 can connect the high-pressure steam heating vessel 430 and the offgas collection header 444 disposed downstream of the high-pressure steam heating vessel 430. In certain embodiments, a gas stream flowing through the eighth pipe 448 can comprise 10% to 30% H2O, such as 15% to 25% H2O or 20% H2O. In certain embodiments, the gas stream can comprise 70% to 85% CO2, such as 75% to 80% CO2 or 77.5% CO2. In certain embodiments, the gas stream can comprise 1% to 4% H2S, such as 2% to 3% H2S or 2.5% H2S. In certain embodiments, the gas stream can comprise 0% to 1 % NH3, such as 0.5% NH3. In certain embodiments, the gas stream can comprise 0% to 1% hydrocarbons, such as 0.5% hydrocarbons. The gas stream can flow through the eighth pipe 448 at a mass flow rate of 300 Ib/h (136.1 kg/h).

[0153] An offgas cooler 450 can be disposed downstream of the offgas collection header 444.

[0154] A ninth pipe 452 can connect the offgas cooler 450 and a sour offgas knockout drum 454 disposed downstream of the offgas cooler 450. Offgas can flow through the ninth pipe 452 at a mass flow rate of 1.1 klb/h (499 kg/h). In certain embodiments, the temperature of the offgas can be from 120 °F to 160 °F (45 °C to 75 °C), such as from 130 °F to 150 °F (50 °C to 70 °C) or 140 °F (60 °C). In certain embodiments, the pressure of the offgas can be from 0 psig to 8 psig (0.1 MPa to 0.2 MPa), such as from 2 psig to 6 psig (0.1 MPa to 0.1 MPa) or at 4 psig (0.1 MPa). Certain examples of the sour offgas knockout drum 454 can have a 4-hour cycle time and a 30- minute drain time.

[0155] A sour water pump 456 can be disposed downstream of the sour offgas knockout drum

454. The sour water pump 456 can comprise a single-stage centrifugal pump. Sour water can exit the sour water pump 456 at a temperature 140 °F (60 °C) and a pressure of 60 psig (0.5 MPa) for combination with HTL emulsion product.

[0156] FIG. 5 is a schematic diagram of a HTL reactor system 500 comprising mixing vessels and flash tanks for a flash heat recovery process (which is also referred to herein as a “steam heat recovery process”), according to another example. The system 500 of FIG. 5 is similar to FIG. 3 and includes additional components and details. The component arrangement, component sizes and performance ratings, temperatures, pressures, dimensions, flow rates, etc., in the description of the system 500 are provided as examples of a representative system configuration and can be varied depending on size, throughput, etc. The system 500 can comprise feed flowing from a feed preparation source 502 at a mass flow rate of 30.8 klb/h (13,970 kg/h). A portion of the feed can flow into a dynamic mixer 506 at a mass flow rate of 28.3 klb/h (12,830 kg/h).

[0157] Feed from the dynamic mixer 506 can flow into a first inlet of a low-pressure steam heating vessel 510 disposed downstream of the dynamic mixer 506 at a mass flow rate of 30.9 klb/h (14,000 kg/h). In certain embodiments, the temperature of the feed can be from 145 °F to 185 °F (60 °C to 85 °C), such as from 155 °F to 175 °F (65 °C to 80 °C) or 165 °F (75 °C). In certain embodiments, the pressure of the feed can be from 5 psig to 25 psig (0.1 MPa to 0.3 MPa), such as from 10 psig to 20 psig (0.2 MPa to 0.2 MPa) or at 15 psig (0.2 MPa).

[0158] In certain embodiments, the low-pressure steam heating vessel 510 can further comprise a pressure indicator (PI), a level indicator (LI), and a high level alarm (HLA). However, the low- pressure steam heating vessel 510, as well as the other vessels disclosed throughout this application, can be coupled to additional or alternative instrumentation for measuring operating conditions.

[0159] The low-pressure steam heating vessel 510 can comprise a second inlet configured to receive a first vaporized water and gas byproducts stream 514 (which is also referred to herein as “first gas stream” or a “first steam stream”). In certain examples, the temperature of the contents of the low-pressure steam heating vessel 510 can be from 100 °F to 400 °F (35 °C to 205 °C), such as from 175 °F to 275 °F (75 °C to 135 °C), 200 °F to 250 °F (90 °C to 125 °C) or 225 °F (107 °C). In certain examples, the pressure of the contents of the low-pressure steam heating vessel 510 can be from 0 psig to 100 psig (0.1 MP to 0.8 MPa), such as from 0 psig to 20 psig (0.1 MPa to 0.2 MPa), 5 psig to 15 psig (0.1 MPa to 0.2 MPa) or at 10 psig (0.2 MPa).

[0160] Feed from the low-pressure steam heating vessel 510 can be received by a low-pressure feed pump 520 at a mass flow rate of 32.8 klb/h (14,880 kg/h). In certain examples, the low- pressure feed pump 520 can comprise a progressive cavity pump with a variable frequency drive (VFD) 521. The VFD 521 can be coupled to the level indicator of the low-pressure steam heating vessel 510. In certain examples, the temperature of the feed exiting the low-pressure feed pump 520 can be from 150 °F to 350 °F (65 °C to 180 °C), such as from 207 °F to 247 °F (95 °C to 120 °C), 217 °F to 237 °F (100 °C to 115 °C) or at 227 °F (108 °C). In certain examples, the pressure of the feed exiting the low-pressure feed pump 520 can be from 230 psig to 270 psig (1.7 MPa to 2 MPa), such as from 240 psig to 260 psig (1.8 MPa to 1.9 MPa), or 250 psig (1.8 MPa). In certain examples, the feed can exit the low-pressure feed pump 520.

[0161] In certain embodiments, a pulsation dampener 522 can be disposed downstream of the low- pressure feed pump 520.

[0162] A first recirculation line 523 comprising a valve can be configured to divert a portion of the feed downstream of the pulsation dampener 522 to a top portion of the low-pressure steam heating vessel 510.

[0163] Downstream of the first pump 520, feed can flow to a static mixer 524. The static mixer 524 can comprise a motor.

[0164] A high-pressure steam heating vessel 530 can be configured to receive feed from the static mixer 524. In certain embodiments, the temperature of the feed can be from 150 °F to 400 °F (65 °C to 205 °C), such as from 230 °F to 310 °F (110 °C to 155 °C), 250 °F to 290 °F (120 °C to 145 °C) or at 270 °F (132 °C). In certain embodiments, the pressure of the feed can be from 175 psig to 275 psig (1.3 MPa to 2.0 MPa), such as from 200 psig to 250 psig (1.5 MPa to 1.8 MPa) or at 225 psig (1.6 MPa). In certain embodiments, the feed can have a mass flow rate of 35.3 klb/h (16,000 kg/h). In certain examples, the contents of the high-pressure steam heating vessel 530 can be heated to a temperature of 220 °F to 420 °F (100 °C to 220 °C), such as a temperature of 270 °F to 370 °F (130 °C to 190 °C), 300 °F to 340 °F (145 °C to 175 °C), 310 °F to 330 °F (150 °C to 170 °C), or 320 °F (160 °C). In certain examples, the pressure of the contents of the high-pressure steam heating vessel 530 can be from 190 psig to 250 psig (1.4 MPa to 1.8 MPa), such as from 200 psig to 240 psig (1.5 MPa to 1.8 MPa), 210 psig to 230 psig (1.6 MPa to 1.7 MPa), or at 220 psig (1.6 MPa). The high-pressure steam heating vessel 530 receives a second vaporized water and gas byproducts stream 534 which is also referred to herein as “second gas stream” or a “second steam stream”). The high-pressure steam heating vessel 530 can further comprise a temperature indicator, a pressure indicator, a high level alarm, and a level indicator.

[0165] Feed can flow out of the high-pressure steam heating vessel 530 and into a high-pressure feed pump 540. In certain examples, the high-pressure feed pump 540 can comprise a centrifugal pump with a variable frequency drive (VFD) 542. In other examples, the high-pressure feed pump 540 can comprise a progressive cavity pump with the VFD 542. The VFD 542 can be coupled to the level indicator of the high-pressure steam heating vessel 530. In certain examples, the temperature of the feed exiting the high-pressure feed pump 540 can be from 290 °F to 370 °F (140 °C to 190 °C), such as from 310 °F to 350 °F (150 °C to 180 °C) or at 330 °F (166 °C). In certain examples, the pressure of the feed exiting the high-pressure feed pump 540 can be from a pressure of 2,600 psig to 3,500 psig (18 MPa to 25 MPa), such as from 2,500 psig to 3,200 psig (17 MPa to 22 MPa), 2,600 psig to 3,000 psig (18 MPa to 21 MPa), 3,000 psig to 3,200 psig (20 MPa to 22 MPa), 3,100 psig to 3,200 psig (21 MP to 22 MPa), 2,700 psig to 2,900 psig (18 MPa to 20 MPa) or at 2,800 psig (20 MPa).

[0166] A second recirculation line 544 can be configured to divert a portion of the feed downstream of the second pump 540 to the high-pressure steam heating vessel 530 to mix and circulate feed within the vessel 530.

[0167] Feed can flow at a mass flow rate of 38.0 klb/h (17,200 kg/h) to a high-pressure (HP) reactor section 560 (which can also be referred to as a “HTL reactor section”), where the organic materials in the feed undergo conversion to liquid and gaseous hydrocarbons including biocrude oil and methane, along with other reaction products. Further details regarding reactor configurations, chemical processes, and catalysts that can be employed in the HP reactor section 560 can be found in U.S. Patent No. 10,167,430 and U.S. Patent No. 9,758,728, which are incorporated herein by reference in their entirety. Certain examples of the HP reactor section 560 can comprise an autothermal HTL reactor as described in greater detail below.

[0168] Product leaves the HP reactor section 560. In certain embodiments, the product can comprise 62% to 82% H2O, such as 67% to 77% H2O or 72% H2O. In certain embodiments, the product can comprise 5% to 25% biocrude, such as 10% to 20% biocrude or 15% biocrude. In certain embodiments, the product can comprise 2.5% to 12.5% solids, such as 5% to 10% solids or 7% solids. In certain embodiments, the product can comprise 3% to 7% CO2, such as 4% to 6% CO2 or 5% CO2. In certain embodiments, the product can comprise 0.2% to 0.6% H2S, such as 0.3% to 0.5% H2S or 0.4% H2S. In certain embodiments, the product can comprise 0.2% to 0.6% NH3, such as 0.3% to 0.5% NH3 or 0.4% NH3. In certain embodiments, the product can comprise 0% to 2% acetic acid, such as 0.5% to 1.5% acetic acid or 1% acetic acid. In certain embodiments, the temperature of the product can be from 350 °F to 550 °F (175 °C to 290 °C), such as from 400 °F to 500 °F (200 °C to 260 °C) or at 450 °F (232 °C). The type and quantity of reaction products can depend on the type and quantity of organic material(s) in the feed. In certain embodiments, the pressure of the product can be from 2,600 psig to 3,500 psig (18 MPa to 25 MPa), such as from 2,500 psig to 3,200 psig (17 MPa to 22 MPa), 2,400 psig to 2,800 psig (16 MPa to 20 MPa), 2,500 psig to 2,700 psig (17 MPa to 19 MPa) or at 2,600 psig (18 MPa). Upon exiting the HP reactor section 560, the product can be in a liquid phase.

[0169] Product flows past a pressure indicator from the HP reactor section 560 to a first letdown valve 570 coupled to the pressure indicator. In certain examples, the first letdown valve 570 can be configured to receive a signal from the pressure indicator or from a pressure controller coupled to the pressure indicator. The first letdown valve 570 can change valve positions (e.g., between a fully open position and a fully closed position) based on the received signal. A first spare pressure letdown valve 572 can optionally be disposed in parallel with the first letdown valve 570. The first spare pressure letdown valve 572 can be a backup valve for use when the first pressure letdown valve 570 is offline.

[0170] In operation, the pressure of the product stream is reduced adiabatically across the first pressure let down valve 570 in a first flashing process. This can result in a two-phase product flow from the first letdown valve 570 to a first vapor- liquid disengagement vessel 580. In certain examples, the initial temperature of the product prior to the first flashing process can be from 250 °F to 650 °F (120 °C to 345 °C), such as from 400 °F to 500 °F (200 °C to 260 °C) or at 450 °F (232 °C). In certain examples, the initial pressure of the product prior to the first flashing process can be from 2,400 psig to 2,800 psig (16 MPa to 20 MPa), such as from 2,500 psig to 2,700 psig (17 MPa to 19 MPa) or at 2,600 psig (18 MPa). In certain examples, the final temperature of the two-phase product after the first flashing process can be from 290 °F to 490 °F (140 °C to 255 °C), such as from 340 °F to 440 °F (170 °C to 230 °C) or at 390 °F (199 °C). In certain examples, the final pressure of the two-phase product after the first flashing process can be from 140 psig to 340 psig (1.1 MPa to 2.4 MPa), such as from 190 psig to 290 psig (1.4 MPa to 2.1 MPa) or at 240 psig (1.8 MPa). The first vapor-liquid disengagement vessel 580 can further comprise a high level alarm, a temperature indicator, a level indicator, and a pressure indicator.

[0171] Product can flow from the first vapor-liquid disengagement vessel 580 at a mass flow rate of 32.6 klb/h (14,800 kg/h). Product can flow through a second letdown valve 574. The second letdown valve 574 can be coupled to the level indicator of the first vapor- liquid disengagement vessel 580. Optionally, a second spare letdown valve 576 can be disposed in parallel with the second letdown valve 574. The second spare letdown valve 576 can be a spare for when the second letdown valve 574 is offline.

[0172] In operation, the pressure of the product stream is reduced adiabatically across the second pressure let down valve 574 in a second flashing process. This can result in a two-phase product flow from the second pressure letdown valve 574 to a second vapor-liquid disengagement vessel 590. In certain examples, the initial temperature of the product stream prior to the second flashing process can be from 290 °F to 490 °F (140 °C to 255 °C), such as from 340 °F to 440 °F (170 °C to 230 °C) or at 390 °F (199 °C). In certain examples, the initial pressure of the product stream prior to the second flashing process can be from 140 psig to 340 psig (1.1 MPa to 2.4 MPa), such as from 190 psig to 290 psig (1.4 MPa to 2.1 MPa) or at 240 psig (1.8 MPa). In certain examples, the final temperature of the two-phase product stream after the second flashing process can be from 150 °F to 400 °F (65 °C to 205 °C), such as from 230 °F to 310 °F (1 10 °C to 155 °C), 250 °F to 290 °F (120 °C to 145 °C) or at 270 °F (132 °C). In certain examples, the final pressure of the two-phase product stream after the second flashing process can be from 0 psig to 100 psig (0.1 MPa to 0.8 MPa), such as from 10 psig to 50 psig (0.2 MPa to 0.4 MPa), 20 psig to 40 psig (0.2 MPa to 0.4 MPa), 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or at 30 psig (0.3 MPa). A two-phase product can flow from the second letdown valve 574 to the second vaporliquid disengagement vessel 590. The second vapor-liquid disengagement vessel 590 can further comprise a high level alarm, a temperature indicator, a level indicator, and a pressure indicator.

[0173] The first gas stream 514 can flow from the second vapor-liquid disengagement vessel 590 and towards the low-pressure steam heating vessel 510 at a mass flow rate of 2.5 klb/h (1,130 kg/h). A startup steam source 516 can feed into the first gas stream 514 upstream of the low- pressure steam heating vessel 510. The first gas stream 514 can flow into the low-pressure steam heating vessel 510 via steam injector 512. A portion 518 of the first gas stream 514 can flow into a plurality of inlets (for example, three inlets) of the dynamic mixer 506 at a mass flow rate of 2.5 klb/h (1,130 kg/h) and can subsequently flow from the dynamic mixer 506 into the low-pressure steam heating vessel 510.In certain examples, the temperature of the first gas stream 514 exiting the second vapor-liquid disengagement vessel 590 can be from 212 °F to 400 °F (100 °C to 205 °C), such as from 230 °F to 310 °F (110 °C to 155 °C), 250 °F to 290 °F (120 °C to 145 °C) or at 270 °F (132 °C). In certain examples, the pressure of the first gas stream 514 exiting the second vaporliquid disengagement vessel 590 can be from 0 psig to 100 psig (0.1 MPa to 0.8 MPa), such as from 10 psig to 50 psig (0.2 MPa to 0.4 MPa), 20 psig to 40 psig (0.2 MPa to 0.4 MPa) 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or at 30 psig (0.3 MPa).

[0174] The second gas stream 534 can flow from the first vapor-liquid disengagement vessel 580 at a mass flow rate of 5.4 klb/h (2,450 kg/h). A first portion of the second gas stream 534 can enter the high-pressure steam heating vessel 530 via steam injector 532 at a mass flow rate of 2.5 klb/h (1,130 kg/h). A second portion of the second gas stream 534 can enter one or more (for example, three) inlets of the static mixer 524 and can subsequently flow into the high-pressure steam heating vessel 530. A startup steam source 536 can feed into the second portion of the second gas stream 534.

[0175] In certain examples, the temperature of the second gas stream 534 exiting the first vaporliquid disengagement vessel 580 can be from 290 °F to 490 °F (140 °C to 255 °C), such as from 340 °F to 440 °F (170 °C to 230 °C) or at 390 °F (199 °C). In certain examples, the pressure of the second gas stream 534 exiting the first vapor- liquid disengagement vessel 580 can be from 140 psig to 340 psig (1.1 MPa to 2.4 MPa), such as from 190 psig to 290 psig (1.4 MPa to 2.1 MPa) or at 240 psig (1.8 MPa).

[0176] Product can How out of the second vapor-liquid disengagement vessel 590 at a mass flow rate of 32.6 klb/h (14, 800 kg/h). A first portion of the product can flow into a water holding tank 596. A second portion of the product can flow into an emulsion product collection header 595 to a recovery section. In certain examples, product entering the recovery section can comprise 66% to 86% H2O, such as 71% to 81% H2O or 76% H2O. In certain examples, the product can comprise 3% to 23% biocrude, such as 8% to 18% biocrude or 13% biocrude. In certain examples, the product can comprise 5% to 15% solids, such as 7.5% to 12.5% solids or 10% solids. In certain examples, the product can comprise 300 ppm to 900 ppm CO2, such as 450 ppm to 750 ppm CO2 or 600 ppm CO2. In certain examples, the product can comprise 150 ppm to 350 ppm H2S, such as 200 ppm to 300 ppm H2S or 250 ppm H2S. In certain examples, the product can comprise 0% to 0.4% NH3, such as 0.2% NH3. In certain examples, the product can comprise 0% to 2% acetic acid, such as 0.5% to 1 .5% acetic acid or 1 % acetic acid.

[0177] In certain examples, the system 500 can comprise a plurality of parallel reactors with similar component arrangements as shown in FIG. 5. For example, a portion of feed from the feed preparation source 502 can flow through a second LP reactor train 503 (which is also referred to herein as “LP reactor train B”), which can include a similar set of mixing vessels, pumps, a reactor section, letdown valves, and vapor-liquid disengagement vessels operating in parallel with those shown. The second LP reactor train 503 can be in communication with the common emulsion product collection header 595.

[0178] In certain examples, the HTL reactor system 500 can further comprise first and second offgas lines 518a and 518b connecting top portions of the low-pressure steam heating vessel 510 and the high-pressure steam heating vessel 530, respectively, and an offgas incinerator section 597 disposed downstream of the first and second offgas lines 518a and 518b. In other examples, the first offgas line 518a can be routed from the low-pressure steam heating vessel 510 to the offgas incinerator section 597, while the second offgas line 518b can be routed from the high-pressure steam heating vessel 530 to the low-pressure steam heating vessel 510.

[0179] In certain examples, any combination of the low-pressure steam heating vessel 510, the high-pressure steam heating vessel 530, the first vapor-liquid disengagement vessel 580, and the second vapor-liquid disengagement vessel 590 can comprise a relief line flowing into a nonflammable relief section 599 configured to dispose of sour water.

[0180] Additionally, although not shown in FIG. 5, the system 500 can include a heat transfer liquid circuit similar to the heat transfer liquid circuit 350 of FIG. 3, and/or additional heaters between the second pump and the HP reactor section 560.

Example 3: Third Representative Hydrothermal Liquefication Reactor System

[0181] The example hydrothermal liquefaction (HTL) reactor systems illustrated in the following figures overcome the previously described fouling issues by transferring heat with steam as a heat transfer medium. Steam — which can comprise vaporized water and gas byproducts generated by the HTL reaction and/or one or a series of adiabatic pressure reductions of the high pressure, high temperature product stream — is injected directly into a colder feed where the steam condenses and releases latent heat to warm the feed. Heat transfer does not occur across a surface boundary, so surface fouling is less likely to affect heat transfer. Since heat transfer is also independent of a heat exchanger surface area, the HTL reactor system can be much cheaper to build because less metal is required to construct heat exchanger surface areas.

[0182] FIG. 6 is a schematic diagram of a HTL reactor system 600 comprising mixing vessels and vapor-liquid disengagement vessels (which are also referred to herein as “flash tanks,” “separation tanks,” and/or “liquid knockout drums”) for a flash heat recovery process, according to a third example. The heat exchange that previously occurred in the heat exchangers of FIGS. 1-2 instead occurs as an exchange of fluid (such as vaporized water and/or gas byproducts from the HTL process) between a vapor-liquid disengagement vessel and a respective mixing vessel. For example, relatively hotter fluid can travel from a second vapor- liquid disengagement vessel 690 to a first mixing vessel 610 to mix with and heat relatively colder biomass slurry disposed in the first mixing vessel 610. In another example, relatively hotter fluid can travel from a first vapor- liquid disengagement vessel 680 to a second mixing vessel 630 to mix with and heat relatively colder biomass slurry disposed in the second mixing vessel 630.

[0183] The HTL reactor system 600 can comprise a biomass slurry source 602, the first mixing vessel 610 disposed downstream of the biomass slurry source 602, a first pump 620 disposed downstream of the first mixing vessel 610, the second mixing vessel 630 disposed downstream of the first pump 620, a second pump 640 disposed downstream of the second mixing vessel 630, a hydrothermal liquefication (HTL) reactor section 660 disposed downstream of the second pump 640, a first pressure letdown valve 670 disposed downstream of the HTL reactor section 660, the first vapor-liquid disengagement vessel 680 disposed downstream of the first pressure letdown valve 670, a second pressure letdown valve 674 disposed downstream of the first vapor-liquid disengagement vessel 680, and the second vapor-liquid disengagement vessel 690 disposed downstream of the second pressure letdown valve 674.

[0184] In certain examples, the HTL reactor system 600 can optionally comprise a heat transfer liquid circuit 650 (which is also referred to herein as a “hot oil loop”). The heat transfer liquid circuit 650 can be configured to recover heat from reactor effluent flowing from the HTL reactor section 660, thereby increasing the heat efficiency of the HTL reactor system 600. The heat transfer liquid circuit 650, the HTL reactor section 660, and the first pressure letdown valve 670 can define a high pressure HTL section 603 (“HP HTL section”), while the remaining components can define a low pressure HTL section 601 (“LP HTL section”).

[0185] In other examples, the optional heat transfer liquid circuit 650 can be replaced with a heat exchanger comprising a cold side and a hot side. Heat can be transferred from a relatively hot product mixture stream flowing through a hot side of the heat exchanger to a relatively cold biomass slurry stream flowing through a cold side of the heat exchanger.

[0186] Although the illustrated HTL reactor system 600 comprises two mixing vessels 610 and 630, other examples of the HTL reactor system 600 can comprise any number of mixing vessels, including one, three, or four mixing vessels with no upper limit. Similarly, although the illustrated HTL reactor system 600 comprises two vapor-liquid disengagement vessels 680 and 690, other examples of the HTL reactor system 600 can comprise any number of vapor- liquid disengagement vessels, including one, three, or four vapor-liquid disengagement vessels with no upper limit.

Although the illustrated HTL reactor system 600 comprises an equal number of mixing vessels 610 and 630 and vapor-liquid disengagement vessels 680 and 690, the HTL reactor system 600 does not need to have an equal number of mixing vessels and vapor-liquid disengagement vessels. Steam injection into the mixing vessels (such as first and second mixing vessels 610 and 630) can take place in a variety of configurations.

[0187] The biomass slurry source 602 (which is also referred to herein as an “aqueous slurry source,” a “feed source,” and/or a “dewatering section”) is configured to dewater a biomass slurry (which is also referred to herein as an “aqueous slurry,” “slurry,” and/or a “feed”). The biomass slurry is dewatered to have a biosolids content (which is also referred to herein a “dry weight”) of 5% to 45%, such as 10% to 40%, 15% to 35%, 20% to 30%, or 0.1% to 25%.

[0188] The first mixing vessel 610 can be disposed downstream of the biomass slurry source 602 and can be configured to receive a first biomass slurry stream 604 from the first biomass slurry source 602. Tn certain embodiments, the temperature of the first biomass slurry stream 604 can be from 50 °F to 110 °F (10 °C to 45 °C), such as from 65 °F to 95 °F (15 °C to 35 °C) or at 80 °F (27 °C). In certain embodiments, the viscosity of the first biomass slurry stream 604 can be from 5,000 cP to 15,000 cP (5 Pa-s to 15 Pa-s), such as from 7,500 cP to 12,500 cP (7.5 Pa- s to 12.5 Pa- s) or at 10,000 cP (10 Pa- s). The first mixing vessel 610 can comprise any vessel capable of retaining a biomass slurry, steam, and gas byproducts. In certain examples, the first mixing vessel 610 can comprise any of a tank, a drum, a canister, and/or a pipe. The first mixing vessel 610 can further comprise a first injector 612 disposed at a below-liquid level of the first mixing vessel 610 during steady state operating conditions.

[0189] The first mixing vessel 610 can be further configured to receive a first vaporized water and gas byproducts stream 614 (which is also referred to herein as a “first gas stream” and/ or a “first steam stream”) via the first injector 612. The first gas stream 614 can comprise vaporized water and gas byproducts. As defined herein, “gas byproducts” can include, but are not limited to, carbon dioxide, hydrogen sulfide, light hydrocarbons, and other non-condensable gases formed by the hydrothermal liquefaction process. The first gas stream 614 can further comprise other byproducts such as ammonia and acetic acid.

[0190] When the first gas stream 614 is injected into the first mixing vessel 610, the first gas stream 614 can mix with the first biomass slurry stream 604 received in the first mixing vessel 610 such that at least a portion of the vaporized water in the first gas stream 614 is absorbed by the biomass slurry of the first biomass slurry stream 604. The biomass slurry disposed in the first mixing vessel 610 can absorb latent heat from the vaporized water and gas byproducts of the first gas stream 614. Thus, this mixing process can heat the biomass slurry disposed in the first mixing vessel 610. In certain embodiments, the temperature of the heated biomass slurry can be from 170 °F to 270 °F (75 °C to 135 °C), such as from 195 °F to 245 °F (90 °C to 120 °C), 212 °F to 270 °F (100 °C to 135 °C), 212 °F to 245 °F (100 °C to 120 °C), or at 220 °F (105 °C). In certain examples, the operating temperature of the first mixing vessel 610 can depend in part on the operating pressure of the first mixing vessel 610 and — since water comprises a portion of the first gas stream 614 — on the vapor-liquid equilibrium line of water. [0191] At least a portion of the gas byproducts flowing into the first mixing vessel 610 can exit a top portion of the first mixing vessel 610 in an offgas stream 618 for acid gas treatment. The offgas stream 618 can exit the first mixing vessel 610 through a valve coupled to the top portion of the first mixing vessel 610. The valve can be coupled to a pressure indicator configured to measure the pressure of the first mixing vessel 610.

[0192] In certain examples, the method of steam and liquid mixing can be selected based at least in part on the viscosity of the first biomass slurry stream 604. For example, active mixing designs such as motorized mixing blades, recirculation pumps, or other mechanical mixers can be used to mix the first biomass slurry stream 604 and the first gas stream 614 due to a high viscosity (on the order of -10,000 cP (10 Pa-s)) of the first biomass slurry stream 604. Optimal mixing designs can be determined on a case-by-case basis for each project and feed properties.

[0193] The first pump 620 can be disposed downstream of the first mixing vessel 610 and can be configured to receive and pressurize a second biomass slurry stream 622 from the first mixing vessel 610. The viscosity of the second biomass slurry stream 622 can be from 1,000 cP to 3,000 cP (1 Pa-s to 3 Pa-s), such as from 1,500 cP to 2,500 cP (1.5 Pa- s to 2.5 Pa- s) or at 2,000 cP (2 Pa- s). In certain examples, the first pump 620 can be a positive displacement pump.

[0194] The second mixing vessel 630 can be configured to receive a third biomass slurry stream 624 from the first pump 620. The pressure of the third biomass slurry stream 624 can be from 140 psig to 240 psig (1 MPa to 2 MPa), such as from 165 psig to 115 psig (1 MPa to 2 MPa) or at 190 psig (1 MPa). The second mixing vessel 630 can comprise any vessel capable of retaining a biomass slurry, steam, and gas byproducts. In certain examples, the second mixing vessel 630 can comprise any of a tank, a drum, a canister, and/or a pipe. The second mixing vessel 630 can further comprise a second injector 632 disposed at a below-liquid level of the second mixing vessel 630 during steady state operating conditions.

[0195] The second mixing vessel 630 can be further configured to receive a second vaporized water and gas byproduct stream 634 (which is also referred to herein as a “second gas stream” and/or a “second steam stream”) entering the second mixing vessel 630 via the second injector 632. The second gas stream 634 can comprise vaporized water and gas byproducts. The second gas stream 634 can further comprise ammonia, acetic acid, and light hydrocarbons.

[0196] In certain examples, the third biomass slurry stream 624 can enter the second mixing vessel 630 through a tangential entry inlet. In certain examples, the second mixing vessel 630 can further comprise wear pads or other design features to avoid erosion of the interior of the second mixing vessel 630 by the third biomass slurry stream 624. [0197] When the second gas stream 634 is injected into the second mixing vessel 630, the second gas stream 634 can mix with the third biomass slurry stream 624 received in the second mixing vessel 630 such that at least a portion of the steam in the second gas stream 634 is absorbed by the biomass slurry of the third biomass slurry stream 624.

[0198] Since the biomass slurry disposed in the second mixing vessel 630 has a relatively lower viscosity than the biomass slurry disposed in the first mixing vessel 610, the second injector 632 of the second mixing vessel 630 can be sufficient for achieving good mixing in the second mixing vessel 630 without the use of additional active mixing designs. However, in other examples the second mixing vessels can include any of the mixing devices and/or systems such as recirculation pumps described herein.

[0199] Introducing the second gas stream 634 can heat the biomass slurry disposed in the second mixing vessel 630. In certain embodiments, the temperature of the heated biomass slurry can be from 270 °F to 370 °F (130 °C to 190 °C), such as from 300 °F to 340 °F (145 °C to 175 °C), 310 °F to 330 °F (150 °C to 170 °C), or at 320 °F (160 °C). In certain examples, the operating temperature of the second mixing vessel 630 can depend in part on the operating pressure of the second mixing vessel 630 and — since water comprises at least a portion of the second gas stream 634 — on the vapor-liquid equilibrium line of water. In certain examples, the operating temperature of the second mixing vessel 630 can depend in part on desired biomass slurry properties and/or a residence time in the second mixing vessel 630. For example, it can be undesirable to heat biomass slurry disposed in the second mixing vessel 630 for a long period of time to above 340 °F (170 °C) because unwanted chemical reactions can occur at such temperatures when biomass slurry is stored at high temperatures for long periods of time. Some unwanted chemical reactions can break down cell structures and denature proteins. Other unwanted chemical reactions can include hydrothermal carbonization, which begins to occur when the biomass slurry is stored for long periods of time at or above 340 °F (170 °C). During hydrothermal carbonization, biomass slurry forms carbon or a solid “biocoal” product that is economically undesirable compared to liquid biocrude product. However, heating the biomass slurry to above 340 °F may not result in such issues if the residence time is sufficiently short (for example, if the mixing the third biomass slurry stream 624 with the second gas stream 634 is a continuous process rather than a batch process).

[0200] However, increasing the temperature of biomass slurry from ambient temperature to 300 °F (150 °C) can cut viscosity by 1 to 2 orders of magnitude. This difference in viscosity can transition biomass slurry flow from laminar to turbulent, desirably increasing the heat transfer rate on hot surfaces. Therefore, increasing the operating temperature of the second mixing vessel 630 and the resulting biomass slurry to at or above 300 °F (150 °C) can better facilitate heat recovery in a heat exchanger downstream of the second mixing vessel 630.

[0201] At least a portion of the gas byproducts disposed in the second mixing vessel 630 can exit a top portion of the second mixing vessel 630 in a third vaporized water and gas byproducts stream 638 (which is also referred to herein as a “third gas stream” and/or a “third steam stream”). The third gas stream 638 can exit the second mixing vessel 630 through a valve coupled to the top portion of the second mixing vessel 630. The third gas stream 638 can comprise steam that is not condensed into the biomass slurry feed (or that re-evaporates), along with non-condensable gases that are not absorbed into the feed. The valve can be coupled to a pressure indicator configured to measure the pressure of the third mixing vessel 630.

[0202] As illustrated, a downstream portion of the third gas stream 638 can be combined with the first gas stream 614 upstream of the first mixing vessel 610. Thus, vaporized water and gas byproducts can flow from the second mixing vessel 630 to the first mixing vessel 610 via the third gas stream 638 and the first gas stream 614. In other examples, the third gas stream 638 can flow directly into the first mixing vessel 610 from the second mixing vessel 630, such as via an injector separate from the injector 612. In such examples, the third gas stream 638 can be arranged in any configuration that allows the third gas stream 638 to flow into the first mixing vessel 610.

However, the HTL reactor system 600 can be arranged in any configuration that allows vaporized water and gas byproducts to flow from the second mixing vessel 630 to the first mixing vessel 610.

[0203] In some examples, the HTL reactor system 600 can lack the third gas stream 638.

[0204] The second pump 640 can be disposed downstream of the second mixing vessel 630. The second pump 640 can be configured to receive and pressurize a fourth biomass slurry stream 642 from the second mixing vessel 630. In certain embodiments, the viscosity of the fourth biomass slurry stream 642 can be from 10 cP to 1000 cP (0.01 Pa. s to 10 Pa- s), such as from 100 cP to 700 cP (0.1 Pa- s), 200 cP to 600 cP (0.2 Pa-s to 0.6 Pa- s), 300 cP to 500 cP (0.3 Pa- s to 0.5 Pa-s), or at 400 cP (0.4 Pa- s).

[0205] In certain examples, the second pump 640 can possibly comprise a centrifugal pump. Typical pumping options can be limited to positive displacement machines (such as piston pumps) for paste-like biomass slurry (such as the biomass slurry in the first biomass slurry stream 604) at ambient temperature. However, if the viscosity of the biomass slurry is lowered to the order of -100 cP or less, dynamic machines such as centrifugal pumps become viable pumping options. The use of centrifugal pumps can be beneficial because centrifugal pumps can be more reliable than positive displacement pumps over long operating periods. Furthermore, centrifugal pumps can be less likely to generate pulsations after each pump discharge, thereby better reducing the likelihood of cycling fatigue and any resulting leaks. Thus, it can be advantageous to select process conditions throughout the HTL reactor system 600 (such as the operating temperature and pressure of the second mixing vessel 630) to lower biomass slurry stream viscosities such that centrifugal pumps can be used.

[0206] Furthermore, since heating biosolids with steam as opposed to heat exchangers can lower the viscosity of the biosolids due to steam exposure, the use of steam injection for heating the biomass slurry can beneficially facilitate the use of centrifugal pumps.

[0207] However, in other examples, the second pump 640 can be a positive displacement pump or any other type of pump.

[0208] In certain examples, the HTL reactor system 600 can further comprise a heat transfer liquid circuit 650 for heating biomass slurry upstream of the HTL reactor section 660 and recovering heat from a product mixture stream downstream of the HTL reactor section 660. The heat transfer liquid circuit 650 can comprise a first heat exchanger 652, a second heat exchanger 654, a heat transfer liquid reservoir 656, and a heat transfer liquid heater 658.

[0209] The first heat exchanger 652 can be disposed downstream of the second pump 640 and can be configured to receive a fifth biomass slurry stream 644 from the second pump 640. The first heat exchanger 652 can also be disposed in the heat transfer liquid circuit 650 downstream of the heat transfer liquid heater 658 and upstream of the second heat exchanger 654. The first heat exchanger 652 can transfer heat from heat transfer liquid flowing through a hot side of the first heat exchanger 652 (e.g., the shell of the first heat exchanger) to biomass slurry flowing through a cold side of the first heat exchanger 652 (e.g., tubes of the first heat exchanger).

[0210] In certain examples, the heat transfer liquid reservoir 656 can be disposed in the heat transfer liquid circuit 650 downstream of the second heat exchanger 654 and upstream of the heat transfer liquid heater 658. In other examples, the heat transfer liquid reservoir 656 can be disposed upstream of the second heat exchanger 654 or at any other location within the heat transfer liquid circuit 650. The heat transfer liquid reservoir 656 can be configured to store heat transfer liquid flowing through the heat transfer liquid circuit 650.

[0211] The heat transfer liquid heater 658 can be disposed in the heat transfer liquid circuit 650 downstream of the heat transfer liquid reservoir 656 and upstream of the first heat exchanger 652. The heat transfer liquid heater 658 can be configured to increase the temperature of heat transfer liquid flowing through the heat transfer liquid circuit 650. [0212] In certain examples, the operating pressure of the heat transfer liquid circuit 650 (e.g., the pressure of the heat transfer liquid circulating through the heat transfer liquid circuit 650) can be from 100 psig to 300 psig (0.8 MPa to 2.2 MPa), such as from 100 psig to 200 psig (0.8 MPa to 1.5 MPa), 120 psig to 210 psig (0.9 MPa to 1.6 MPa), 150 psig to 200 psig (1.1 MPa to 1.5 MPa), 155 psig (1.2 MPa), etc. Advantageously, the relatively low-pressure heat transfer liquid circuit 650 can allow the shells of the first and second heat exchangers 652 and 654 to be less thick than in existing configurations where the liquids to exchange heat are both at high pressures. This can significantly reduce the material quantities required to produce the first and second heat exchangers 652 and 654 and reduce the capital cost of the HTL reactor system 600 accordingly.

[0213] The HTL reactor section 660 can be disposed downstream of the first heat exchanger 652 and is configured to receive a sixth biomass slurry stream 662 from the first heat exchanger 652. In certain examples where the HTL reactor system 600 does not comprise the heat transfer liquid circuit 650, the HTL reactor section 660 can be configured to receive the fifth biomass slurry stream 644 from the second pump 640. The HTL reactor section 660 can comprise one or more HTL reactors, which can be configured according to any of the reactors described herein. In certain examples, one or more of the HTL reactors can be an autothermal HTL reactor (FIG. 14). As discussed later in this application, particularly with respect to FIG. 14, autothermal HTL reactors are configured to oxidize biomass slurry under elevated temperature and pressures to spontaneously combust the biomass slurry. The one or more HTL reactors can be configured to produce a product mixture from biomass slurry. The product mixture can exit the HTL reactor section 660 in a first product mixture stream 664 comprising liquid water and biocrude, among other reaction products. In certain examples, the first product mixture stream 664 can further comprise biosolids. In certain examples, the first product mixture stream 664 can further comprise vaporized water and/or gas byproducts.

[0214] The HTL reactor section 660 can optionally comprise additional components (such as heaters) for preparing the sixth biomass slurry stream 662 received from the first heat exchanger 652 and/or additional components (such as coolers or heat exchangers) for removing and/or recovering heat from the first product mixture stream 664 exiting the HTL reactor section 660. In other examples, the system can comprise a heater in addition to, or in place of, the heat transfer liquid circuit 650, to directly heat the biomass feed. In other examples, the system can comprise a heat exchanger in place of the heat transfer liquid circuit 650 to transfer heat from product flowing through the hot side of the heat exchanger to biomass slurry flowing through the cold side of the heat exchanger. [0215] In certain examples, the operating temperature of the HTL reactor section 660 can be from 400 °F to 800 °F (205 °C to 430 °C), such as from 500 °F to 750 °F (260 °C to 400 °C), 550 °F to 750 °F (290 °C to 398.9 °C), 600 °F to 700 °F (315 °C to 375 °C), or 650 °F (343 °C). In certain examples, the operating pressure of the HTL reactor section 660 can be from 1,000 psig to 4,000 psig (7 MPa to 28 MPa), such as from 1,500 psig to 3,500 psig (10 MPa to 25 MPa), 3,000 psig to 3,200 psig (20 MPa to 22 MPa), 3,100 psig to 3,200 psig (21 MP to 22 MPa), 2,000 psig to 3,000 psig (13 MPa to 21 MPa), 2,500 psig to 3,200 psig (17 MPa to 22 MPa), or 2,500 psig (17 MPa).

[0216] The second heat exchanger 654 can be disposed downstream of the HTL reactor section 660 and can be configured to receive the first product mixture stream 664 from the HTL reactor section 660. The second heat exchanger 654 can also be disposed in the heat transfer liquid circuit 650 downstream of the first heat exchanger 652 and upstream of the oil reservoir 656. The second heat exchanger 654 can be configured to recover heat from the first product mixture stream 664 by transferring heat from the product mixture stream 664 flowing through a hot side of the second heat exchanger 654 (e.g., a shell of the heat exchanger) to the heat transfer oil flowing through a cold side of the second heat exchanger 654 (e.g., tubes of the heat exchanger). A second product mixture stream 671 can leave the second heat exchanger 654. In certain examples, the temperature of the second product mixture stream 671 can be from 350 °F to 550 °F (175 °C to 290 °C), such as from 400 °F to 500 °F (200 °C to 60 °C) or 450 °F (232 °C). As discussed later in relation to FIGS. 8A-8B, the temperature of the second product mixture stream 671 can impact how much steam is generated in subsequent flashing steps.

[0217] The first pressure letdown valve 670 can be disposed downstream of the second heat exchanger 654 and can be configured to receive the second product mixture stream 671 from the second heat exchanger 654. In certain embodiments, the temperature of the received second product mixture stream 671 can be from 350 °F to 550 °F (175 °C to 290 °C), such as from 400 °F to 500 °F (200 °C to 260 °C) or at 450 °F (232 °C). The first pressure letdown valve 670 can comprise a valve coupled to a pressure measurement and control loop disposed upstream of the first pressure letdown valve 670. The first pressure letdown valve 670 can be configured to reduce the pressure of product mixture of the second product mixture stream 671 in a first flashing process. In certain embodiments, the pressure of the second product mixture stream 671 prior to the first flashing process can be from 350 °F to 550 °F (175 °C to 290 °C), such as from 400 °F to 500 °F (200 °C to 60 °C) or 450 °F (232 °C). In certain embodiments, the pressure of the second product mixture stream 671 prior to the first flashing process can be from 2,400 psig to 2,800 psig (16 MPa to 20 MPa), such as from 2,500 psig to 2,700 psig (17 MPa to 19 MPa), 2,550 psig to 2,650 psig (17 MPa-19 MPa), or at 2,600 psig (18 MPa). In certain embodiments, the temperature of a third product mixture stream 673 exiting the first pressure letdown valve 670 after the first flashing process can be from 270 °F to 470 °F (130 °C to 245 °C), such as from 320 °F to 420 °F (160 °C to 220 °C) or at 370 °F (190 °C). In certain embodiments, the pressure of the third product mixture stream 673 after the first flashing process can be from 150 psig to 250 psig (1.1 MPa to 1.8 MPa), such as from 175 psig to 225 psig (1.3 MPa to 1.7 MPa) or at 200 psig (1.5 MPa). The first flashing process can vaporize 5% to 50% (such as 30% to 50%, 35% to 50%, 40% to 50%, 40% to 45%, 43%, 6% to 16%, or 11%) of the water in the second product mixture stream 671.

[0218] In certain examples where the HTL reactor system 600 does not comprise the heat transfer liquid circuit 650, the first pressure letdown valve 670 can be downstream of the HTL reactor section 660 and can be configured to receive the first product mixture stream 664 from the HTL reactor section 660.

[0219] The first vapor-liquid disengagement vessel 680 can be disposed downstream of the first pressure letdown valve 670 and can be configured to receive the third product mixture stream 673 from the first pressure letdown valve 670. In certain embodiments, the pressure of the third product mixture stream 673 entering the first vapor-liquid disengagement vessel 680 can be from 150 psig to 250 psig (1 MPa to 2 MPa), such as from 175 psig to 225 psig (1 MPa to 2 MPa), or at 200 psig (2 MPa). The third product mixture stream 673 can be a two-phase flow comprising biocrude, liquid water, and steam (wherein steam can include vaporized water and gas byproducts). In some examples, the third product mixture stream 673 can further comprise biosolids, thereby making the third product mixture stream 673 a three-phase flow. The first vapor-liquid disengagement vessel 680 can be configured to separate the vaporized water and gas byproducts from the liquid water and biosolids of the third product mixture stream 673. The separated vaporized water and gas byproducts can be routed to the second mixing vessel 630 in the second gas stream 634. In certain embodiments, the temperature of the second gas stream 634 exiting the first vapor-liquid disengagement vessel 680 can be from 270 °F to 470 °F (130 °C to 245 °C), such as from 320 °F to 420 °F (160 °C to 220 °C) or at 370 °F (190 °C). In certain embodiments, the pressure of the second gas stream 634 exiting the first vapor-liquid disengagement vessel 680 can be from 150 psig to 250 psig (1.1 MPa to 1.8 MPa), such as from 175 psig to 225 psig (1.3 MPa to 1.7 MPa) or at 200 psig (1.5 MPa). The second gas stream 634 can exit a top portion of the first vapor-liquid disengagement vessel 680.

[0220] The first vapor-liquid disengagement vessel 680 can comprise any vessel capable of retaining a multi-phase (such as a two-phase) product mixture stream. In certain examples, the first vapor-liquid disengagement vessel 680 can comprise any of a tank, a drum, a canister, and/or a pipe. In certain examples, the first vapor- liquid disengagement vessel 680 can further comprise wear pads, a tangential entry inlet, or other design features to reduce erosion of the interior of the first vapor-liquid disengagement vessel 680 by the third product mixture stream 673. The first vapor-liquid disengagement vessel 680 can further comprise a level indicator configured to measure a liquid level within the first vapor-liquid disengagement vessel 680.

[0221] The operating pressure of the first vapor- liquid disengagement vessel 680 can be greater than the operating pressure of the second mixing vessel 630 to maintain fluid flow from the first vapor-liquid disengagement vessel 680 to the second mixing vessel 630. In certain examples, the minimum pressure difference between the operating pressure of the first vapor-liquid disengagement vessel 680 and the operating pressure in the second mixing vessel 630 can be the sum of the frictional pressure drop in a line carrying the second gas stream 634, the pressure drop across the second injector 632, and the pressure required to overcome the liquid level head pressure in the second mixing vessel 630.

[0222] The operating pressure of the first vapor- liquid disengagement vessel 680 may be selected to optimize the amount of heat recovered from steam injection. For example, a lower pressure in the first vapor-liquid disengagement vessel 680 can result in more water vaporizing in the second flashing process, which can further result in product mixture leaving the first vapor-liquid disengagement vessel 680 at a lower temperature (which is an indication of increased heat recovery). In such examples, the operating pressures of the first mixing vessel 610 and the second mixing vessel 630 can be selected to achieve optimal heat recovery for the overall HTL reactor system 600.

[0223] The second pressure letdown valve 674 can be disposed downstream of the first vaporliquid disengagement vessel 680 and can be configured to receive the fourth product mixture stream 675 from the first vapor-liquid disengagement vessel 680. The second pressure letdown valve 674 can comprise a valve coupled to the level indicator of the first vapor-liquid disengagement vessel 680.

[0224] The second pressure letdown valve 674 can be configured to reduce the pressure of product mixture of the fourth product mixture stream 675 in a second flashing process. In certain embodiments, the temperature of the fourth product mixture stream 675 prior to the second flashing process can be from 270 °F to 470 °F (130 °C to 245 °C), such as from 320 °F to 420 °F (160 °C to 220 °C) or at 370 °F (190 °C). In certain embodiments, the pressure of the fourth product mixture stream 675 prior to the second flashing process can be from 150 psig to 250 psig (1.1 MPa to 1 .8 MPa), such as from 175 psig to 225 psig (1.3 MPa to 1.7 MPa) or at 200 psig (1.5 MPa). In certain embodiments, the temperature of a fifth product mixing stream 677 exiting the second pressure letdown valve 674 after the second flashing process can be from 210 °F to 310 °F (95 °C to 155 °C), such as from 235 °F to 285 °F (110 °C to 145 °C) or at 260 °F (127 °C). In certain embodiments, the pressure of the fifth product mixing stream 677 exiting the second pressure letdown valve 674 after the second flashing process can be from 5 psig to 50 psig (0.1 MPa to 0.4 MPa), such as from 20 psig to 40 psig (0.2 MPa to 0.4 MPa), 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or at 30 psig (0.3 MPa). In certain embodiments, the second flashing process can vaporize 3% to 33% (such as 8% to 28%, 10% to 30%, 18% to 28%, 20% to 25%, 22%, 13% to 23%, or 18%) of the liquid water in the fourth product mixture stream 675. The second pressure letdown valve 674 can comprise a valve coupled to the level indicator of the first vapor-liquid disengagement vessel 680. In certain examples, the second pressure letdown valve 674 can act as a level control valve for the first vapor-liquid disengagement vessel 680.

[0225] The second vapor-liquid disengagement vessel 690 can be disposed downstream of the second pressure letdown valve 674 and can be configured to receive the fifth product mixture stream 677 from the second pressure letdown valve 674. In certain embodiments, the pressure of the fifth product mixture stream 677 can be from 5 psig to 50 psig (0.1 MPa to 0.4 MPa), such as from 20 psig to 40 psig (0.2 MPa to 0.4 MPa), 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or at 30 psig (0.3 MPa). The fifth product mixture stream 677 can comprise biosolids, liquid water, vaporized water, and gas byproducts. The second vapor-liquid disengagement vessel 690 can be configured to separate the vaporized water and gas byproducts from the liquid water and biosolids of the fifth product mixture stream 677. The separated vaporized water and gas byproducts can be routed to the first mixing vessel 610 in a fourth vaporized water and gas byproducts stream 692 (which is herein referred to as a “fourth gas stream”). In certain embodiments, the temperature of the fourth gas stream 692 can be from 210 °F to 310 °F (95 °C to 155 °C), such as from 235 °F to 285 °F (110 °C to 145 °C) or at 260 °F (127 °C). In certain embodiments, the pressure of the fourth gas stream 692 can be from 5 psig to 50 psig (0.1 MPa to 0.4 MPa), such as from 20 psig to 40 psig (0.2 MPa to 0.4 MPa), 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or at 30 psig (0.3 MPa). The fourth gas stream 692 can exit a top portion of the second vapor-liquid disengagement vessel 690.

[0226] In some examples, the HTL reactor system 600 can lack the second vapor-liquid disengagement vessel 690.

[0227] In some examples, the fourth gas stream 692 can be combined with the third gas stream 638 to form the first gas stream 614 which flows into the first mixing vessel 610. In other examples, the fourth gas stream 692 can flow directly from the second vapor-liquid disengagement vessel 690 to the first mixing vessel 610. However, the fourth gas stream 692 can be arranged in any configuration that allows the fourth gas stream 692 to flow either directly or indirectly into the first mixing vessel 610. In certain examples, the pressure of the fourth gas stream 692 and the pressure of the third gas stream 638 can each be greater than the pressure of the first biomass slurry stream 604 in the first mixing vessel 610 to prevent backflow.

[0228] The HTL reactor system 600 can further comprise a HTL emulsion product storage 696 for storing product mixture. The HTL emulsion product storage 696 can be disposed downstream of the second vapor-liquid disengagement vessel 690 and is configured to receive a sixth product mixture stream 694 from the second vapor-liquid disengagement vessel 690.

[0229] As previously mentioned, the HTL reactor system 600 can comprise other configurations for recovering heat from steam, vaporized water, and/or gas byproducts. For example, a vaporized water and gas byproducts stream can flow from the sixth product mixture stream 694 to the first biomass slurry stream 604. The first biomass slurry stream 604 can mix with and absorb latent heat from the vaporized water and gas byproducts stream before entering the first mixing vessel 610. In another example, a vaporized water and gas byproducts stream can flow from the second gas stream 634 to the fourth gas stream 692. The vaporized water and gas byproducts can mix with and transfer latent heat to steam (e.g., vaporized water and gas byproducts) in the second gas stream 634.

[0230] FIG. 7 is a schematic diagram of a HTL reactor system 700 comprising mixing vessels and flash tanks for a flash heat recovery process, according to a fourth example. The system 700 of FIG. 7 can be similar to the system 600 of FIG. 6 with additional components and details that may or may not be present in a real- world implementation, depending upon the particular design of the system. The component arrangement, component sizes and performance ratings, temperatures, pressures, dimensions, flow rates, etc., in the description of the system 700 are provided as examples of a representative system configuration and can be varied depending on size, throughput, etc. The HTL reactor system 700 can comprise a biomass slurry source 702, a first mixing vessel 710 disposed downstream of the biomass slurry source 702, a first pump 720 disposed downstream of the first mixing vessel 710, a second mixing vessel 730 disposed downstream of the first pump 720, a second pump 740 disposed downstream of the second mixing vessel 730, a hydrothermal liquefication (HTL) reactor section 760 disposed downstream of the second pump 740, a first pressure letdown valve 770 disposed downstream of the HTL reactor section 760, a first vaporliquid disengagement vessel 780 disposed downstream of the first pressure letdown valve 770, a second pressure letdown valve 774 disposed downstream of the first vapor-liquid disengagement vessel 780, and a second vapor-liquid disengagement vessel 790 disposed downstream of the second pressure letdown valve 774.

[0231] The biomass slurry source 702 (which is also referred to herein as an “aqueous slurry source,” a “feed source,” and/or a “dewatering section”) can be configured to dewater the biomass slurry. In certain embodiments, the biomass slurry can be dewatered to have a biosolids content (which is also referred to herein a “dry weight”) of 5% to 45%, such as 10% to 40%, 15% to 35%, 20% to 30%, or 0.1% to 25%. In certain embodiments, the temperature of the biomass slurry can be from 50 °F to 110 °F (10 °C to 45 °C), such as from 65 °F to 95 °F (15 °C to 35 °C) or at 80 °F (27 °C). In certain embodiments, the pressure of the biomass slurry can be from 20 psig to 120 psig (0.2 MPa to 0.9 MPa), such as from 45 psig to 95 psig (0.4 MPa to 0.8 MPa) or at 70 psig (0.6 MPa).

[0232] A first biomass slurry stream 704 can flow from the biomass slurry source 702 to the first mixing vessel 710. In certain embodiments, the temperature of the first biomass slurry stream 704 can be from 40 °F to 200 °F (0 °C to 95 °C), such as from 50 °F to 110 °F (10 °C to 45 °C), 65 °F to 95 °F (15 °C to 35 °C) or at 80 °F (27 °C). In certain embodiments, the pressure of the first biomass slurry stream 704 can be from 0 psig to 20 psig (0.1 MPa to 0.2 MPa), such as from 5 psig to 15 psig (0.1 MPa to 0.2 MPa) or at 10 psig (0.2 MPa). The first biomass slurry stream 704 has a mass flow rate of 28.3 klb/h (12,800 kg/h).

[0233] The first mixing vessel 710 can be disposed downstream of the biomass slurry source 702 and can be configured to receive the first biomass slurry stream 704 from the biomass slurry source 702. The first mixing vessel 710 can comprise any vessel capable of retaining a biomass slurry, steam, and gas byproducts. In certain examples, the first mixing vessel 710 can comprise any of a tank, a drum, a canister, and/or a pipe. The first mixing vessel 710 can further comprise a first injector 712 disposed at a below-liquid level of the first mixing vessel 710 during steady state operating conditions.

[0234] The first mixing vessel 710 can be further configured to receive a first vaporized water and gas byproducts stream 714 (which is also referred to herein as a “first gas stream” and/or a “first steam stream”) via the first injector 712. Certain embodiments of the first vaporized water and gas byproducts stream 714 can have a mass flow rate of 6.1 klb/h (2,760 kg/h). The first mixing vessel 710 can be configured to mix biomass slurry from the first biomass slurry stream 704 with vaporized water and gas byproducts from the first gas stream 714 to heat the biomass slurry. In certain examples, the temperature of the heated biomass slurry from the first biomass slurry stream 704 can be from 100 °F to 350 °F (35 °C to 180 °C), such as from 180 °F to 280 °F (80 °C to 140 °C), 205 °F to 255 °F (95 °C to 125 °C) or at 230 °F (110 °C). In certain examples, the pressure of the heated biomass slurry from the first biomass slurry stream 704 can be from 0 psig to 20 psig (0.1 MPa to 0.2 MPa), such as from 5 psig to 15 psig (0.1 MPa to 0.2 MPa) or at 10 psig (0.2 MPa). At least a portion of the vaporized water from the first gas stream 714 can be absorbed by the biomass slurry disposed in the first mixing vessel 710.

[0235] The first mixing vessel 710 can further comprise a pressure indicator, a high level alarm, and a level indicator. In certain examples, the first mixing vessel 710 can comprise a mechanical mixer for facilitating the mixing of the biomass slurry, vaporized water, and gas byproducts. For example, the HTL reactor system 700 can comprise a first recirculation pump 726 which mixes the contents of the first mixing vessel 710 by recycling biomass slurry.

[0236] Gas byproducts can exit a top portion of the first mixing vessel 710 in an offgas stream 718 at a mass flow rate of 1.7 klb/h (770 kg/h). The offgas stream 718 can exit the first mixing vessel 710 through a valve coupled to the top portion of the first mixing vessel 710 and flows to an offgas incinerator section 797. The valve can be coupled to a pressure indicator configured to measure the pressure of the first mixing vessel 710. In certain embodiments, the offgas stream 718 can comprise 50% to 90% water, such as 60% to 80% water or 70% water. In certain embodiments, the offgas stream 718 can comprise 5% to 45% CO2, such as 25% to 45% CO2, 15% to 35% CO2, 20% to 30% CO2, 30% to 40% CO2, or 25% CO2. In certain embodiments, the offgas stream 718 can comprise 0.5% to 4.5% H2S, such as 1 .5% to 3.5% H2S or 2.5% H2S. In certain embodiments, the offgas stream 718 can comprise 0.5% to 3% ammonia, such as 1.5% to 2.5% ammonia or 1.5% ammonia. In certain embodiments, the offgas stream 718 can comprise 0% to 2% light hydrocarbons, such as 0.5% to 1.5% light hydrocarbons or 1% light hydrocarbons.

[0237] A second biomass slurry stream 722 can exit a bottom portion of the first mixing vessel 710 and can flow to the first pump 720 and the first recirculation pump 726 disposed downstream of the first mixing vessel 710.

[0238] The first pump 720 can be disposed downstream of the first mixing vessel 710 and can be configured to receive at least a portion of the second biomass slurry stream 722 from the first mixing vessel 710. The first pump 720 can comprise a progressive cavity pump and a variable frequency drive (VFD) 721.

[0239] The first recirculation pump 726 can be disposed downstream of the first mixing vessel 710 and can be configured to receive at least a portion of the second biomass slurry stream 722. The first recirculation pump 726 can be configured to recycle biomass slurry back to the first mixing vessel 710 via a first recirculation stream 728 to achieve better mixing in the first mixing vessel 710. The first recirculation pump 726 can comprise a progressive cavity pump and a variable frequency drive (VFD) 727.

[0240] A third biomass slurry stream 724 can flow from the first pump 720 to the second mixing vessel 730. The third biomass slurry stream 724 can have a mass flow rate of 33 klb/h (15,000 kg/h). The third biomass slurry stream 724 can be received by the second mixing vessel 730.

[0241] The second mixing vessel 730 can be disposed downstream of the first pump 720 and can be configured to receive the third biomass slurry stream 724. The second mixing vessel 730 can comprise any vessel capable of retaining a biomass slurry, steam, and gas byproducts. In certain examples, the second mixing vessel 730 can comprise any of a tank, a drum, a canister, and/or a pipe. The second mixing vessel 730 can further comprise a second injector 732 disposed at a below-liquid level of the second mixing vessel 730 during steady state operating conditions. The second mixing vessel 730 can further comprise a pressure indicator, a high level alarm, a temperature indicator, and a level indicator.

[0242] The second mixing vessel 730 can be further configured to receive a second vaporized water and gas byproducts stream 734 (which is also referred to herein as a “second gas stream”) via the second injector 732. The second gas stream 734 can enter the second mixing vessel 730 at a mass flow rate of 5.6 klb/h (2,540 kg/h).

[0243] The second mixing vessel 730 can be configured to mix biomass slurry from the third biomass slurry stream 724 with vaporized water and gas byproducts from the second gas stream 734 to heat biomass slurry from the third biomass slurry stream 724. In certain examples, the temperature of the heated biomass slurry from the third biomass slurry stream 724 can be from 200 °F to 450 °F (90 °C to 235 °C), such as from 270 °F to 370 °F (130 °C to 190 °C), 300 °F to 340 °F (145 °C to 175 °C), 310 °F to 330 °F (150 °C to 170 °C), or at 320 °F (160 °C). In certain examples, the pressure of the heated biomass slurry from the third biomass slurry stream 724 can be from 190 psig to 250 psig (1.4 MPa to 1.8 MPa), such as from 200 psig to 240 psig (1.5 MPa to 1.8 MPa), 210 psig to 230 psig (1.6 MPa to 1.7 MPa), or at 220 psig (1.6 MPa). At least a portion of the vaporized water from the second gas stream 734 can be absorbed by the biomass slurry from the third biomass slurry stream 724 during the mixing process.

[0244] A third vaporized water and gas byproducts stream 738 (which is also referred to herein as a “third gas stream”) can exit a top portion of the second mixing vessel 730 at a mass flow rate of 0.2 klb/h (90 kg/h). The third gas stream 738 can exit the second mixing vessel 730 through a control valve coupled to the top portion of the second mixing vessel 730. The control valve can be coupled to a pressure indicator configured to measure the pressure of the second mixing vessel 730.

[0245] As illustrated, the third gas stream 738 feeds into the first gas stream 714 such that vaporized water and gas byproducts flow from the second mixing vessel 730 to the first mixing vessel 710 via the third gas stream 738 and the first gas stream 714. Tn other examples, the third gas stream 738 can flow directly into the first mixing vessel 710 from the second mixing vessel 730 without intersecting the first gas stream 714. However, the third gas stream 738 can be arranged in any configuration that allows the third gas stream 738 to flow from the second mixing vessel 730 into the first mixing vessel 710.

[0246] A fourth biomass slurry stream 742 can exit a bottom portion of the second mixing vessel 730.

[0247] A second recirculation pump 746 can be disposed downstream of the second mixing vessel 730 and can be configured to receive the fourth biomass slurry stream 742 from the second mixing vessel 730. The second recirculation pump 746 can comprise a progressive cavity pump with a variable frequency drive (VFD) 747.

[0248] A fifth biomass slurry stream 744 can exit the second recirculation pump 746. In certain embodiments, the temperature of the fifth biomass slurry stream 744 can be from 200 °F to 450 °F (90 °C to 235 °C), such as from 300 °F to 340 °F (145 °C to 175 °C), 310 °F to 330 °F (150 °C to 170 °C) or at 320 °F (160 °C). In certain embodiments, the pressure of the fifth biomass slurry stream 744 can be from 150 psig to 350 psig (1.1 MPa to 2.5 MPa), such as from 200 psig to 300 psig (1.5 MPa to 2.1 MPa) or at 250 psig (1.8 MPa). Certain examples of the fifth biomass slurry stream 744 can have a mass flow rate of 38.5 klb/h (17,400 kg/h). The fifth biomass slurry stream 744 can flow past a pulsation dampener 745. The fifth biomass slurry stream 744 can be received by a first basket strainer 748a and a second basket strainer 748b disposed in parallel with each other. Differential pressure sensors (“DP sensors”) can be disposed in parallel with each of the first basket strainer 748a and the second basket strainer 748b.

[0249] A second recirculation stream 750 can flow from the fifth biomass slurry stream 744 to the second mixing vessel 730. The flow rate of the second recirculation stream 750 can be adjusted to control the pressure of the fifth biomass slurry stream 744. Controlling the pressure of the fifth biomass slurry stream 744 can provide suction pressure to the second pump 740.

[0250] The second pump 740 can be disposed downstream of the first and second basket strainers 748a and 748b and can be configured to receive a sixth biomass slurry stream 752 from the basket strainers. Certain embodiments of the second pump 740 can comprise a variable flow drive (VFD) 741. The second pump 740 can comprise a progressive cavity pump or a centrifugal pump.

[0251] The HTL reactor section 760 can be disposed downstream of the second pump 740 and can be configured to receive a seventh biomass slurry stream 762 from the second pump 740. The HTL reactor section 760 can comprise one or more HTL reactors for converting biomass slurry into a product mixture comprising liquid water and biocrude. In certain examples, one or more of the HTL reactors can comprise an autothermal HTL reactor. As discussed later in this application, the autothermal HTL reactor can be configured to oxidize the biomass slurry from the seventh biomass slurry stream 762 under elevated temperature and pressure to spontaneously combust the biomass slurry. In certain examples, the product mixture can further comprise gas byproducts such as CO2, H2S, and other non-condensable gases. In certain examples, the product mixture can further comprise solids, wherein certain compositions of solids can include biosolids. In certain examples, the product mixture can further comprise acetic acid and ammonia.

[0252] In certain embodiments, the seventh biomass slurry stream 762 can enter the HTL reactor section at a temperature of 500 °F to 800 °F (260 °C to 430 °C), such as at a temperature of 550 °F to 750 °F (285 °C to 400 °C), 600 °F to 700 °F (315 °C to 375 °C), 500 °F to 650 °F (260 °C to 345 °C), 650 °F to 800 °F (340 °C to 430 °C), etc. In certain embodiments, the seventh biomass slurry stream 762 can enter the HTL reactor section at a pressure of 1,000 psig to 4,000 psig (7 MPa to 28 MPa), such as at a pressure of 1,500 psig to 3,500 psig (10 MPa to 25 MPa), 2,000 psig to 3,000 psig (13 MPa to 21 MPa), 2,500 psig to 3,200 psig (17 MPa to 22 MPa), 3,000 psig to 3,200 psig (20 MPa to 22 MPa), 3,100 psig to 3,200 psig (21 MP to 22 MPa), 2,400 psig to 2,800 psig (16 MPa to 20 MPa), 2,500 psig to 2,700 psig (17 MPa to 19 MPa), 2,550 psig to 2,650 psig (17 MPa to 19 MPa), 2,600 psig (18 MPa), etc.

[0253] In certain examples, the HTL reactor section 760 can optionally comprise additional components (such as heaters) for preparing the seventh biomass slurry stream 762 received from the second pump 740 and/or additional components (such as coolers or heat exchangers) for removing and/or recovering heat from the first product mixture stream 764 exiting the HTL reactor section 760. In certain examples, the HTL reactor section 760 can comprise a heat transfer liquid circuit for recovering heat from product mixture leaving the HTL reactor section 760. The heat transfer liquid circuit can be similar to the heat transfer liquid circuit 650 illustrated in FIG. 6.

[0254] A first product mixture stream 764 can exit the HTL reactor section 760. In certain examples, the temperature of the first product mixture stream 764 can be from 300 °F to 800 °F (145 °C to 430 °C), such as from 350 °F to 750 °F (175 °C to 400 °C), 350 °F to 550 °F (175 °C to 290 °C), 400 °F to 500 °F (200 °C to 260 °C), 550 °F to 750 °F (285 °C to 400 °C), or at 450 °F (230 °C). In certain examples, the pressure of the first product mixture stream 764 can be from 1,000 psig to 4,000 psig (7 MPa to 28 MPa), such as from 2,400 psig to 2,800 psig (16 MPa to 20 MPa), 2,500 psig to 2,700 psig (17 MPa to 19 MPa), 2,550 psig to 2,650 psig (17 MPa to 19 MPa), or at 2,600 psig (18 MPa). The first product mixture stream 764 can have a mass flow rate of 38.5 klb/h (17,500 kg/h). The first product mixture stream 764 can comprise the product mixture generated by the HTL reactor section 760. In certain embodiments, the first product mixture stream 764 can comprise 52% to 92% H2O, such as 62% to 82% H2O or 72% H2O. In certain embodiments, the first product mixture stream 764 can comprise 5% to 25% biocrude, such as 10% to 20% biocrude or 15% biocrude. In certain embodiments, the first product mixture stream 764 can comprise 1% to 13% solids, such as 4% to 10% solids or 7% solids. In certain embodiments, the first product mixture stream 764 can comprise 1% to 9% CO2, such as 3% to 7% CO2 or 5% CO2. In certain embodiments, the first product mixture stream 764 can comprise 0.1% to 0.8% H2S, such as 0.2% to 0.6% H2S or 0.4% H2S. In certain embodiments, the first product mixture stream 764 can comprise 0.1% to 0.8% NH3, such as 0.2% to 0.6% NH3 or 0.4% NH3. In certain embodiments, the first product mixture stream 764 can comprise 0.5% to 1.5% acetic acid, such as 1% acetic acid.

[0255] The first pressure letdown valve 770 can be disposed downstream of the HTL reactor section 760 and can be configured to receive the first product mixture stream 764 from the HTL reactor section 760. The first pressure letdown valve 770 can be configured to reduce the pressure of product mixture flowing through the first pressure letdown valve 770 in a first flashing process. In certain examples, the first flashing process can comprise an adiabatic pressure reduction. In certain examples, the temperature of the product mixture prior to the first flashing process can be from 300 °F to 800 °F (145 °C to 430 °C), such as from 350 °F to 750 °F (175 °C to 400 °C), 350 °F to 550 °F (175 °C to 290 °C), 400 °F to 500 °F (200 °C to 260 °C), 550 °F to 750 °F (285 °C to 400 °C), or at 450 °F (230 °C). In certain examples, the pressure of the product mixture prior to the first flashing process can be from 1,000 psig to 4,000 psig (7 MPa to 28 MPa), such as from 2,400 psig to 2,800 psig (16 MPa to 20 MPa), 2,500 psig to 2,700 psig (17 MPa to 19 MPa), 2,550 psig to 2,650 psig (17 MPa to 19 MPa), or at 2,600 psig (18 MPa). In certain examples, the reduced pressure of the product mixture flowing through the first pressure letdown valve 770 after the first flashing process can be from 140 to 340 psig (1.1 MPa to 2.4 MPa), such as from 190 psig to 290 psig (1.4 MPa to 2.1 MPa) or at 240 psig (1.8 MPa). In certain embodiments, the temperature of the product mixture flowing through the first pressure letdown valve 770 after the first flashing process can be from 290 °F to 490 °F (140 °C to 255 °C), such as from 340 °F to 440 °F (170 °C to 230 °C) or at 390 °F (200 °C).

[0256] In certain examples, a first spare pressure letdown valve 772 can optionally be disposed in parallel with the first pressure letdown valve 770. The first spare pressure letdown valve 772 can be a valve configured to be a spare valve for use when the first pressure letdown valve 770 is offline, thereby beneficially improving the maintainability and serviceability of the HTL reactor system 700. Certain embodiments of the HTL reactor system 700 can lack the optional first spare pressure letdown valve 772.

[0257] A second product mixture stream 773 can exit the first and/or the first spare pressure letdown valves 770 and 772. The second product mixture stream 773 can be a two-phase mixture comprising a liquid phase and a gaseous phase. In certain embodiments, the temperature of the second product mixture stream 773 can be from 290 °F to 490 °F (140 °C to 255 °C), such as from 340 °F to 440 °F (170 °C to 230 °C) or at 390 °F (200 °C). In certain embodiments, the pressure of the second product mixture stream 773 can be from 140 psig to 340 psig (1.1 MPa to 2.4 MPa), such as from 190 psig to 290 psig (1.4 MPa to 2.1 MPa) or at 240 psig (1.8 MPa). The second product mixture stream 773 can flow to the first vapor-liquid disengagement vessel 780. In some examples, a pipe through which the second product mixture stream 773 flows can be designed to reduce the possibility of blowouts due to the high velocity and high solids content of the second product mixture stream 773. For example, the pipe can be substantially straight to reduce the occurrence of piping elbows which change the flow direction of the second product mixture stream 773 and can be reinforced at critical locations with materials resistant to erosion..

[0258] The first vapor-liquid disengagement vessel 780 can be disposed downstream of the first and first spare pressure letdown valves 770, 772 and can be configured to receive the second product mixture stream 773 from the first and first spare pressure letdown valves 770, 772. The first vapor-liquid disengagement vessel 780 can comprise any vessel capable of retaining the two- phase product mixture. In certain examples, the first vapor-liquid disengagement vessel 780 can comprise any of a tank, a drum, a canister, and/or a pipe. In certain examples, the first vapor- liquid disengagement vessel 780 can further comprise a tangential inlet configured to receive the second product mixture stream 773, wear pads disposed inside the first vapor-liquid disengagement vessel 780, or other features which mitigate erosion resulting from the entry of the second product mixture stream 773 into the first vapor-liquid disengagement vessel 780. In certain examples, the first vapor-liquid disengagement vessel 780 can further comprise internal assemblies, such as baffles, shrouds, or mist elimination pads to facilitate the separation of vaporized water and gas byproducts from liquid water of the product mixture.

[0259] The first vapor-liquid disengagement vessel can be configured to separate vaporized water and gas byproducts from the second product mixture stream 773. For example, the liquid phase can fall to the lower portion of the vessel and the gas phase can rise to the top of the vessel. The first flashing process can vaporize 5% to 50% (such as 30% to 50%, 40% to 50%, 38% to 45%, 6% to 16%, or 11%) of the water in the second product mixture stream 773. The separated vaporized water and gas byproducts can form the second vaporized water and gas byproducts stream 734 which exits the first vapor-liquid disengagement vessel at a mass flow rate of 5.6 klb/h (2,540.1 kg/h).

[0260] A first startup steam source 779 can be configured to inject startup steam into the second vaporized water and gas byproducts stream 734 upstream of the second mixing vessel 730.

[0261] A third product mixture stream 775 can exit the first vapor- liquid disengagement vessel 780 at a mass flow rate of 32.8 klb/h (14,900 kg/h). In certain embodiments, the temperature of the third product mixture stream 775 as it exits the first vapor-liquid disengagement vessel 780 can be from 290 °F to 490 °F (140 °C to 255 °C), such as from 340 °F to 440 °F (170 °C to 230 °C) or at 390 °F (200 °C). In certain embodiments, the pressure of third product mixture stream 775 as it exits the first vapor-liquid disengagement vessel 780 can be from 140 psig to 340 psig (1. MPa to 3 MPa), 190 psig to 290 psig (1 MPa to 3 MPa), or at 240 psig (2 MPa).

[0262] The second pressure letdown valve 774 can be disposed downstream of the first vaporliquid disengagement vessel 780 and can be configured to receive the third product mixture stream 775 from the first vapor-liquid disengagement vessel 780. The second pressure letdown valve 774 can be a valve coupled to the level indicator of the first vapor-liquid disengagement vessel 780.

The second pressure letdown valve 774 can be configured to reduce the pressure of product mixture flowing through the first pressure letdown valve 770 in a second flashing process. In certain embodiments, the second flashing process can be an adiabatic pressure reduction. In certain embodiments, the temperature of product mixture entering the second pressure letdown valve 774 prior to the second flashing process can be from 290 °F to 490 °F (140 °C to 255 °C), such as from 340 °F to 440 °F (170 °C to 230 °C) or at 390 °F (300 °C). In certain embodiments, the pressure of product mixture entering the second pressure letdown valve 774 prior to the second flashing process can be from 140 psig to 340 psig (1 MPa to 3 MPa), 190 psig to 290 psig (1 MPa to 3 MPa), or at 240 psig (2 MPa). In certain embodiments, the pressure of the flashed product mixture exiting the second pressure letdown valve 774 can be from 5 psig to 65 psig (0.1 MPa to 0.6 MPa), such as from 15 psig to 55 psig (0.2 MPa to 0.5 MPa), 25 psig to 45 psig (0.3 MPa to 0.4 MPa), 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or at 35 psig (0.3 MPa). In certain embodiments, the temperature of the flashed product mixture exiting the second pressure letdown valve 774 can be from 230 °F to 330 °F (125 °C to 150 °C), such as from 255 °F to 305 °F (130 °C to 145 °C) or at 280 °F (138 °C). In certain embodiments, the pressure reduction can vaporize 3% to 33% (such as 8% to 28%, 10% to 30%, 18% to 28%, 20% to 25%, 22%, 13% to 23%, or 18%) of water in the third product mixture stream 775 to produce 6.1 klb/h (2,770 kg/h) of flash steam, which can comprise vaporized water and gas byproducts.

[0263] An optional second spare pressure letdown valve 776 can be disposed in parallel with the second pressure letdown valve 774. The second spare pressure letdown valve 776 can be a valve configured to be a spare valve for use when the second pressure letdown valve 774 is offline, thereby beneficially improving the maintainability and serviceability of the HTL reactor system 700. It should be understood that certain embodiments of the HTL reactor system 700 can lack the optional second spare pressure letdown valve 776.

[0264] A fourth product mixture stream 778 can exit the second and/or second spare pressure letdown valves 774 and 776. The fourth product mixture stream 778 can be a two-phase mixture. In certain embodiments, the temperature of the fourth product mixture stream 778 exiting the pressure letdown valves 774 and 776 can be from 230 °F to 330 °F (125 °C to 150 °C), such as from 255 °F to 305 °F (130 °C to 145 °C) or at 280 °F (138 °C). In certain embodiments, the pressure of the fourth product mixture stream 778 exiting the pressure letdown valves 774 and 776 can be from 5 psig to 55 psig (0.2 MPa to 0.5 MPa), such as from 25 psig to 45 psig (0.3 MPa to 0.4 MPa), 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or at 35 psig (0.3 MPa). The fourth product mixture stream 778 can flow to the second vapor-liquid disengagement vessel 790. In some examples, a pipe through which the fourth product mixture stream 778 flows can be designed to mitigate the possibility of blowouts due to the high velocity and high solids content of the fourth product mixture stream 778. For example, the pipe can be substantially straight to reduce the number of piping elbows which redirect the flow of product mixture and can be reinforced at selected locations with materials resistant to corrosion

[0265] The second vapor-liquid disengagement vessel 790 can be disposed downstream of the second and second spare pressure letdown valves 774 and 776 and can be configured to receive the fourth product mixture stream 778 from the second and second spare pressure letdown valves 774, 776. The second vapor-liquid disengagement vessel 790 can comprise any vessel capable of retaining the two-phase product mixture. In certain examples, the second vapor-liquid disengagement vessel 790 can comprise any of a tank, a drum, a canister, and/or a pipe. In certain examples, the second vapor-liquid disengagement vessel 790 can further comprise a tangential inlet configured to receive the fourth product mixture stream 778, wear pads disposed inside the second vapor-liquid disengagement vessel 790, or other features which can help mitigate erosion resulting from the entry of the fourth product mixture stream 778 into the second vapor- liquid disengagement vessel 790. In certain examples, the second vapor-liquid disengagement vessel 790 can further comprise internal assemblies, such as baffles, shrouds, or mist elimination pads to facilitate the separation of vaporized water and gas byproducts from liquid water of the product mixture. The second vapor-liquid disengagement vessel 790 can further comprise a level indicator, a high level alarm, a pressure indicator, and a temperature indicator. However, in certain examples, the second vapor-liquid disengagement vessel 790 can comprise additional instrumentation depending on the particular implementation of the HTL reactor system 700.

[0266] The second vapor-liquid disengagement vessel 790 can be configured to separate vaporized water and gas byproducts from the product mixture stream. The separated vaporized water and gas byproducts can form a fourth vaporized water and gas byproducts stream 792 (which is also referred to herein as a “fourth gas stream”) which can exit the second vapor-liquid disengagement vessel 790 at a mass flow rate of 6.1 klb/h (2,770 kg/h). In certain embodiments, the temperature of the fourth gas stream 792 exiting the second vapor-liquid disengagement vessel 790 can be from 200 °F to 400 °F (90 °C to 205 °C), such as from 225 °F to 305 °F (105 °C to 155 °C), 245 °C to 285 °F (115 °C to 145 °C) or at 265 °F (130 °C). In certain embodiments, the pressure of the fourth gas stream 792 exiting the second vapor-liquid disengagement vessel 790 can be from 5 psig to 45 psig (0.1 MPa to 0.4 MPa), such as from 15 psig to 35 psig (0.2 MPa to 0.3 MPa), 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or at 25 psig (0.3 MPa).

[0267] A second startup steam source 793 can be configured to inject startup steam into the fourth gas stream 792 upstream of the first mixing vessel 710.

[0268] The third gas stream 738 and the fourth gas stream 792 can be merged upstream of the first mixing vessel 710 to form the first gas stream 714. In certain examples, there can be a pressure differential between the third gas stream 738 and the fourth gas stream 792. For example, the pressure of the third gas stream 738 (such as 240 psig (1.8 MPa)) can be greater than the pressure of the fourth gas stream 792 (such as 25 psig (0.3 MPa)). In certain examples, the pressure of the third gas stream 738 and the pressure of the fourth gas stream 792 can each be greater than the pressure of the biomass slurry disposed in the first mixing vessel 710 (such as 10 psig (0.1 MPa). In certain examples, the pressure of the third gas stream 738 and the pressure of the fourth gas stream 792 can each be at least 5 psi (0.1 MPa) greater than the pressure of the biomass slurry disposed in the first mixing vessel 710 (such as 10 psig (0.1 MPa). In certain examples, the third gas stream 738 and the fourth gas stream 792 do not have to be merged upstream of the first mixing vessel 710 and can instead enter the first mixing vessel 710 through different outlets of the first mixing vessel 710. In certain examples, the HTL reactor system 700 can include additional components (such as check valves) to prevent the backflow of steam into the third gas stream 738 and/or the fourth gas stream 792.

[0269] In certain embodiments, the temperature of the fifth product mixture stream 794 can be from 220 °F to 300 °F (100 °C to 150 °C), such as from 240 °F to 280 °F (115 °C to 140 °C) or at 260 °F (127 °C). In certain embodiments, the pressure of the fifth product mixture stream 794 can be from 0 psig to 40 psig (0.1 MPa to 0.4 MPa), such as from 10 psig to 30 psig (0.2 MPa to 0.3 MPa), 5 psig to 20 psig (0.1 MPa to 0.4 MPa), 5 psig to 10 psig (0.1 MPa to 0.2 MPa), or at 20 psig (0.2 MPa). Certain embodiments of the fifth product mixture stream 794 can have a mass flow rate of 26.7 klb/h (12,100 kg/h). A first portion of the fifth product mixture stream 794 can flow into a water holding tank 796. A second portion of the fifth product mixture stream 794 can flow into an emulsion product collection header 795 to a recovery section. In certain examples, product mixture entering the recovery section can comprise 56% to 96% H2O, such as 66% to 86% H2O or 76% H2O. In certain examples, the product mixture can comprise 3% to 23% biocrude, such as 8% to 18% biocrude or 13% biocrude. In certain examples, the product mixture can comprise 5% to 15% solids, such as 7.5% to 12.5% solids or 10% solids. In certain examples, the product mixture can comprise 300 ppm to 900 ppm CO2, such as 450 ppm to 750 ppm CO2 or 600 ppm CO2. In certain examples, the product mixture can comprise 150 ppm to 350 ppm H2S, such as 200 ppm to 300 ppm H2S or 250 ppm H2S. In certain examples, the product mixture can comprise 0.1% to 0.3% NH3, such as 0.2% NH3. In certain examples, the product mixture can comprise 0.5% to 1.5% acetic acid, such as 1% acetic acid.

[0270] In certain examples, a portion of biomass slurry from the biomass slurry source 702 can flow through a second LP reactor train 703 (which is also referred to herein as “LP reactor train B”), which can include a similar set of mixing vessels, pumps, a reactor section, letdown valves, and vapor- liquid disengagement vessels operating in parallel with those shown. The second LP reactor train 703 can be in fluid communication with the emulsion product collection header 795.

[0271] As previously mentioned, the offgas stream 718 can flow into the offgas incinerator section 797. The offgas incinerator section 797 can be configured to dispose of sour offgas. [0272] Any combination of the first mixing vessel 710, the second mixing vessel 730, the first vapor-liquid disengagement vessel 780, and the second vapor- liquid disengagement vessel 790 can comprise a relief line flowing into a non-flammable relief section 799 configured to dispose of sour water. FIGS. 8A-8B are phase diagrams 800 for aqueous HTL reactor effluent that illustrate the temperature and pressure of the HTL effluent during different cooling processes, according to one example. Each phase diagram 800 comprises an X-axis corresponding to HTL reactor effluent temperature, a y-axis corresponding to HTL reactor effluent pressure, and a vapor-liquid equilibrium line 802 separating a liquid region 804 and a vapor region 806. The illustrated phase diagrams 800 are the phase diagrams for water because the HTL reactor effluent is approximated as water in these particular examples for simplicity. However, it should be understood that HTL reactor effluent can comprise additional or alternative fluids than water. Thus, the phase diagrams for different compositions of HTL reactor effluent and/or different HTL reactor systems may differ from the phase diagrams 800 illustrated in these figures.

[0273] HTL reactor effluent leaving the HTL reactor can be at a very high energy state due to the high HTL reactor temperature of 500 °F to 750 °F (260 °C to 400 °C) and the high HTL reactor pressure of 1000 psig to 4000 psig (7.0 MPa to 27.7 MPa). The HTL reactor effluent can be returned to a low energy state before the product mixture exits the HTL reactor system. Suddenly reducing the pressure of the HTL reactor effluent can vaporize a portion of the water in the HTL reactor effluent. For example, dropping the pressure of the HTL reactor effluent from 2,650 psig (18.4 MPa) to 200 psig (1.5 MPa) can vaporize 64% of the water and cool the system to 370 °F (190 °C).

[0274] FIG. 8A is a phase diagram 800 illustrating the temperature and pressure of HTL reactor effluent throughout a one-step cooling process that approximates an adiabatic flashing process, according to one example. The initial pressure and temperature of the HTL reactor effluent (indicated by star 808) are 2500 psig (17.2 MPa) and 650 °F (343 °C). During the one-step cooling process, the pressure of the HTL reactor effluent is reduced at a constant temperature such that the HTL reactor effluent remains in the liquid region 804. The pressure of the HTL reactor effluent is further reduced along the vapor-liquid equilibrium line 802 (indicated by arrows 810) to vaporize the HTL reactor effluent and generate steam. The final pressure and temperature of the HTL reactor effluent (indicated by star 812) is 200 psig (1.5 MPa) and 370 °F (188 °C). Lower final pressures result in more HTL reactor effluent vaporization and lower final temperatures. For example, a final state of 200 psig (1.5 MPa) results in 64% of the water being converted to water vapor with a final temperature of 370 °F (188 °C). [0275] FIG. 8B is a phase diagram 800 illustrating the temperature and pressure of HTL reactor effluent throughout a two-step cooling process, according to one example. The initial pressure and temperature of the HTL reactor effluent (indicated by star 808) are 2500 psig (17.2 MPa) and 650 °F (343 °C). During a first step of the two-step cooling process, the HTL reactor effluent is cooled (indicated by arrow 814) to 450 °F (232 °C) at a constant pressure. In certain examples, the first step of the two-step cooling process can be performed by a heat exchanger proceeding the adiabatic flash step. The state of the HTL reactor effluent after the first step is indicated by star 816. During a second step of the two-step cooling process, an adiabatic pressure drop takes place (indicated by arrow 818) to reduce the pressure from 2,500 psig (17 MPa) to 200 psig (1.5 MPa). Note that the final temperature is the same in the processes illustrated in FIGS. 8A and 8B. However, the amount of water vapor formed in the process illustrated in FIG. 8B is only 11% of the water in the HTL reactor effluent. Less steam is formed because less energy is available to vaporize the water due to the initial cooling step (indicated by arrow 814) removing energy from the HTL reactor effluent.

[0276] The two example processes mapped to the phase diagrams 800 in FIGS. 8A-8B show how water vapor formation can be controlled by varying the final pressure of the HTL reactor effluent and the amount of cooling or heat recovery before the pressure drop. These two parameters allow for precise control of heat recovery. Accurate temperature control is important because the fluid viscosity is a strong function of temperature.

[0277] FIG. 9 is a schematic diagram of a HTL reactor system 900 comprising modular heat recovery assemblies 907 for a flash heat recovery process, according to one example. The HTL reactor system 900 can comprise a low-pressure HTL section 901 and a high-pressure HTL section 903. The low-pressure HTL section 901 can comprise a biomass slurry source 902, which can be similar to other biomass slurry sources disclosed in this application. The low-pressure HTL section 901 can further comprise a generic number (n) of modular heat recovery assemblies 907a, 907b, and 907n.

[0278] Although three modular heat recovery assemblies 907a, 907b, and 907n are depicted in the illustrated example, the generic number (n) can be any number of modular heat recovery assemblies (including one, two, four, five, six, etc.) with no upper limit. The number of desired heat recovery assemblies 907 can depend on various design considerations. For example, a high number of modular heat recovery assemblies 907 can increase recovery efficiency because recovery efficiency improves with the number of flashing steps. However, a low number of modular heat recovery assemblies 907 can lower equipment cost, increase reliability of the HTL reactor system 900, and reduce staffing levels required to operate the HTL reactor system 900.

[0279] Each modular heat recovery assembly 907 can comprise a mixing vessel 910a, 910b, and 910n connected to a corresponding vapor-liquid disengagement vessel 980a, 980b, and 980n. Biomass slurry from the biomass slurry source 902 can be mixed sequentially with vaporized water and gas byproducts in each mixing vessel 910a, 910b, and 910n from the corresponding vaporliquid disengagement vessel 980a, 980b, and 980n, thereby transferring heat from the vaporized water and gas byproducts to the biomass slurry. Heated biomass slurry can flow into a HTL reactor section 960 disposed in the high-pressure HTL section 903. The HTL reactor section 960 can be similar to other HTL reactors and HTL reactor sections disclosed throughout this application. In certain examples, the HTL reactor section 960 can comprise an autothermal HTL reactor. Product mixture can flow from the HTL reactor section 960 and can be flashed sequentially in each vaporliquid disengagement vessel 980a, 980b, and 980n to separate vaporized water and gas byproducts from the product mixture. The separated vaporized water and gas byproducts from each vaporliquid disengagement vessel 980a, 980b, and 980n can be sent to the respective mixing vessel 910a, 910b, 910n to heat biomass slurry disposed in each of the respective mixing vessels 910a, 910b, 910n. Product mixture can then sent to an emulsion product storage 996, which can be similar to other product storages disclosed throughout this application.

[0280] FIG. 10 is a perspective view a HTL reactor system 1000 comprising modular heat recovery assemblies 1007 for a flash heat recovery process, according to one example. The illustrated HTL reactor system 1000 can comprise two modular heat recovery assemblies 1007a and 1007b. Each of the modular heat recovery assemblies 1007a and 1007b can comprise a single, modular structure comprising a mixing vessel 1010a and 1010b connected to a corresponding vapor-liquid displacement vessel 1080a and 1080b. The mixing vessels 1010a and 1010b can be similar to other mixing vessels disclosed throughout this application, and vapor- liquid displacement vessels 1080a and 1080b can be similar to other vapor-liquid displacement vessels disclosed throughout this application. In certain examples, the mixing vessels 1010a and 1010b can be of similar size as the corresponding vapor-liquid displacement vessels 1080a and 1080b. Although only two modular heat recovery assemblies 1007 are illustrated, the HTL reactor system 100 can comprise a generic number (n) of modular heat recovery assemblies 1007 with no upper limit. Each modular heat recovery assembly 1007 can be paired with a corresponding pump 1020a and 1020b, which can be similar to other pumps disclosed throughout this application. Each modular heat recovery assembly 1007 can be paired with a corresponding pressure letdown valve 1070a and 1070b, which can be similar to other pressure letdown valves disclosed throughout this application. [0281] Biomass slurry can flow sequentially from a biomass slurry source 1002 through the first mixing vessel 1010a, through the first pump 1020a, through the second mixing vessel 1010b, and through the second pump 1020b towards a HTL reactor (in the direction indicated by arrow 1062). The biomass slurry can be mixed with vaporized water and gas byproducts in each of the mixing vessels 1010a and 1010b. Product mixture comprising biocrude can flow sequentially from the HTL reactor (in the direction indicated by arrow 1064) through the second pressure letdown valve 1070b, through the second vapor-liquid disengagement vessel 1080b, through the first pressure letdown valve 1070a, and through the first vapor-liquid disengagement vessel 1080a to towards an emulsion product storage 1096. Vaporized water and gas byproducts can be separated from the product mixture in flashing processes at each vapor-liquid disengagement vessel 1080a and 1080b.

[0282] FIG. 11 is a process flow diagram 1100 illustrating a method of producing biocrude using steam heat recovery, according to one example. The method described by the process flow diagram 1100 can be performed using HTL reactor systems disclosed throughout this application. In particular, the method can be performed using any of the exemplary HTL processing schemes and HTL reactor systems illustrated in FIGS. 3-7, 9-10, and 14.

[0283] The first block 1105 of the process flow diagram 1100 corresponds to a first step of mixing a first biomass slurry stream with a first vaporized water and gas byproducts stream (which is also referred to herein as a “first gas stream” and/or a “first steam stream”) to heat biomass slurry of the first biomass slurry stream to a first temperature. In certain embodiments, the first temperature can be from 170 °F to 270 °F (75 °C to 1 5 °C), such as from 185 °F to 265 °F (85 °C to 130 °C), 195 °F to 245 °F (90 °C to 120 °C), 205 °F to 245 °F (95 °C to 120 °C), 220 °F to 230 °F (100 °C to 110 °C), or 223 °F to 227 °F (105 °C to 110 °C). Mixing the first biomass slurry stream with the first gas stream can result in a second biomass slurry stream. In certain examples, the first step can be performed in a mixing vessel similar to other mixing vessels (such as mixing vessels 310, 410, 510, 610, 710, 910, 1010, etc.) disclosed throughout this application.

[0284] The process flow diagram 1100 comprises a second block 1 1 10 corresponding to a second step of pressurizing the second biomass slurry stream to a first pressure. In certain examples, the first pressure can be from 90 psig to 350 psig (0.7 MPa to 2.5 MPa), such as from 140 psig to 300 psig (1.1 MPa to 2.2 MPa), 165 psig to 275 psig (1.2 MPa to 2.0 MPa), or 190 psig to 250 psig (1.4 MPa to 1.8 MPa). Pressurizing the second biomass slurry stream can result in a third biomass slurry stream. In certain examples, the second step can be performed using a pump similar to other pumps (such as pumps 320, 420, 520, 620, 720, 1020, etc.) disclosed throughout this application. [0285] The process flow diagram 1100 comprises a third block 1115 corresponding to a third step of mixing the third biomass slurry stream with a second vaporized water and gas byproducts stream (which is also referred to herein as a “second gas stream” and/or a “second steam stream”) to heat biomass slurry of the third biomass slurry stream to a second temperature. In certain embodiments, the second temperature can be from 270 °F to 750 °F (130 °C to 400 °C), such as from 270 °F to 370 °F (130 °C to 190 °C), 300 °F to 340 °F (150 °C to 170 °C), 310 °F to 330 °F (150 °C to 170 °C), 315 °F to 325 °F (155 °C to 165 °C), 550 °F to 750 °F (285 °C to 400 °C), 600 °F to 700 °F (315 °C to 375 °C), 625 °F to 675 °F (325 °C to 360 °C), or 645 °F to 655 °F (345 °C to 350 °C). Mixing the third biomass slurry stream with the second gas stream can result in a fourth biomass slurry stream. In certain examples, the third step can be performed in a mixing vessel similar to other mixing vessels (such as mixing vessels 330, 430, 530, 630, 730, 910, 1010, etc.) disclosed throughout this application.

[0286] The process flow diagram 1100 comprises a fourth block 1120 corresponding to a fourth step of forming a third vaporized water and gas byproducts stream (which is also referred to herein as a “third gas stream” and/or a “third steam stream”) from the mixture of the third biomass slurry stream and the second gas stream. In certain examples, the third step and the fourth step can be performed concurrently. In certain examples, the fourth step can be performed in a mixing vessel that can be similar to other mixing vessels (such as mixing vessels 330, 430, 530, 630, 730, 910, 1010 etc.) disclosed throughout this application.

[0287] The process flow diagram 1100 comprises a fifth block 1 125 corresponding to a step of pressurizing the fourth biomass slurry stream to a second pressure. In certain examples, the second pressure can be from 200 psig to 4000 psig (1.5 MPa to 27.7 MPa), such as from 1,000 psig to 4,000 psig (7 MPa to 27.7 MPa), 1,500 psig to 3,500 psig (10.4 MPa to 24.2 MPa), 2,000 psig to 3,000 psig (13.9 MPa to 20.8 MPa), 2,500 psig to 3,000 psig (17.3 MPa to 20.8 MPa), 3,000 psig to 3,200 psig (20 MPa to 22 MPa), 3,100 psig to 3,200 psig (21 MP to 22 MPa), 2,400 psig to 2,800 psig (16.7 MPa to 19.4 MPa), 2,500 psig to 2,700 psig (17.3 MPa to 18.7 MPa), or 2,550 psig to 2,650 psig (17.7 MPa to 18.4 MPa). Pressurizing the fourth biomass slurry can result in a fifth biomass slurry stream. In certain examples, the fifth step can be performed using a pump similar to other pumps (such as pumps 340, 440, 540, 640, 740, 1020, etc.) disclosed throughout this application.

[0288] The process flow diagram 1100 comprises a sixth block 1130 corresponding to an optional sixth step of heating the fifth biomass slurry stream to a third temperature. In certain embodiments, the third temperature can be from 500 °F to 750 °F (260 °C to 398.9 °C), such as from 550 °F to 750 °F (285 °C to 400 °C), 600 °F to 700 °F (315 °C to 375 °C), 625 °F to 675 °F (325 °C to 360 °C), or 645 °F to 655 °F (345 °C to 350 °C). Heating the fifth biomass slurry stream results in a sixth biomass slurry stream. In certain examples, the optional sixth step can be performed using a heat exchanger (such as heat exchangers 352 and 652 belonging to heat transfer liquid circuits 350 and 650) disclosed throughout this application.

[0289] The process flow diagram 1100 comprises a seventh block 1135 corresponding to a seventh step of converting the sixth biomass slurry stream into a first product mixture stream, wherein the first product mixture stream comprises biocrude and liquid water. In embodiments of the method that lack the optional step of heating the fifth biomass slurry stream to the third temperature, this step can instead comprise converting the fifth biomass slurry stream into the first product mixture stream. In certain examples, the seventh step can be performed using a HTL reactor or a HTL reactor section similar to other HTL reactors and HTL reactor sections (such as HTL reactor sections 160, 560, 660, 760, 960, etc.) disclosed throughout this application. In certain examples, an autothermal HTL reactor can be used to perform the seventh step.

[0290] The process flow diagram 1100 comprises an eighth block 1140 corresponding to an optional eighth step of cooling the first product mixture stream to a fourth temperature. In certain embodiments, the fourth temperature can be from 350 °F to 550 °F (175 °C to 290 °C), such as from 400 °F to 500 °F (200 °C to 260 °C), 425 °F to 475 °F (215 °C to 250 °C), or 445 °F to 455 °F (225 °C to 235 °C). Cooling the first product mixture stream can result in a second product mixture stream. In certain examples, the optional eighth step can be performed using a heat exchanger similar to other heat exchangers (such as heat exchangers 354, 654 belonging to heat transfer liquid circuits 350, 650) disclosed throughout this application.

[0291] The process flow diagram 1100 comprises a ninth block 1145 corresponding to a ninth step of separating the second gas stream from the second product mixture stream. In embodiments of the method that lack the optional eighth step of cooling the first product mixture stream, the ninth step can instead comprise separating the second gas stream from the first product mixture stream in a first flashing process. The ninth step can comprise reducing the pressure of the second product mixture stream to a third pressure. In certain embodiments, the third pressure can be from 140 psig to 340 psig (1.1 MPa to 2.4 MPa), 190 psig to 290 psig (1.4 MPa to 2.1 MPa), 215 psig to 265 psig (1.6 MPa to 1.9 MPa), or 235 psig to 245 psig (1.7 MPa to 1.8 MPa). Reducing the pressure of the second product mixture stream can vaporize 1% to 50% (such as 30% to 50%, 40% to 50%, 35% to 45%, 40% to 45%, 43%, 6% to 16%, 8% to 14%, or 11%) of the water in the second product mixture stream. In certain examples, reducing the pressure of the second product mixture stream can be performed using a pressure letdown valve similar to other pressure letdown valves (such as pressure letdown valves 370, 570, 670, 770, 1070, etc.) disclosed throughout this application.

[0292] The ninth step further comprises separating vaporized water and gas byproducts produced by the pressure reduction from liquid water and biocrude to form the second gas stream. In certain examples, separating vaporized water and gas byproducts from the second product mixture stream can be performed using a vapor-liquid disengagement vessel similar to other vapor- liquid disengagement vessels (such as vapor-liquid disengagement vessels 380, 580, 680, 780, 980, 1080, etc.) disclosed throughout this application. In certain examples, reducing the pressure of the second product mixture stream and separating the vaporized water and gas byproducts can be done concurrently. Separating the vaporized water and gas byproducts can result in two streams: the second gas stream and a third product mixture stream.

[0293] The process flow diagram 1100 comprises a tenth block 1150 corresponding to a tenth step of separating a fourth vaporized water and gas byproducts stream (which is also referred to herein as a “fourth gas stream” and/or a “fourth steam stream”) from the third product mixture stream. The tenth step comprises reducing the pressure of the third product mixture stream to a fourth pressure in a second flashing step. In certain examples, the fourth pressure can be from 10 psig to 50 psig (0.2 MPa to 0.4 MPa), 20 psig to 40 psig (0.2 MPa to 0.4 MPa), or 25 psig to 35 psig (0.3 MPa to 0.4 MPa). Reducing the pressure of the third product mixture stream can vaporize 3% to 33% (such as 8% to 28%, 18% to 28%, 10% to 30%, 20% to 25%, 22%, 13% to 23%, or 18%) of the liquid water in the third product mixture stream. In certain examples, reducing the pressure of the third product mixture stream can be performed using a pressure letdown valve similar to other pressure letdown valves (such as pressure letdown valves 374, 574, 674, 774, 1070, etc.) disclosed throughout this application.

[0294] The tenth step further comprises separating vaporized water and gas byproducts produced by the pressure reduction from liquid water and biocrude of the second product mixture stream to form the fourth gas stream. In certain examples, separating vaporized water and gas byproducts can be performed using a vapor-liquid disengagement vessel similar to other vapor- liquid disengagement vessels (such as vapor-liquid disengagement vessels 390, 590, 690, 790, 980, 1080, etc.) disclosed throughout this application. In certain examples, reducing the pressure of the third product mixture stream and separating the vaporized water and gas byproducts can be done concurrently. Separating the vaporized water and gas byproducts can result in two streams: the fourth gas stream and a fourth product mixture stream. [0295] The process flow diagram 1100 comprises an eleventh block 1155 corresponding to an eleventh step of forming the first gas stream by combining the third gas stream and the fourth gas stream. In certain examples, the third gas stream and the fourth gas stream can be combined upstream of where the first biomass slurry stream is mixed with the first gas stream. In other examples, the third gas stream and the fourth gas stream can be combined when the first biomass slurry stream is mixed with the first gas stream.

[0296] The process flow diagram 1100 comprises a twelfth block 1160 corresponding to a twelfth step of supplying the first gas stream to the first mixing vessel for mixing with the first biomass slurry stream.

[0297] Although the illustrated process flow diagram 1100 includes blocks representing different steps of the method arranged in a particular order, other exemplary process flow diagrams and their corresponding methods can be arranged in any other suitable order. Furthermore, at least some of the steps can be performed concurrently. Finally, although the process flow diagram 1100 includes two blocks 1105, 1115 corresponding to first and second mixing steps, two blocks 1110, 1125 corresponding to first and second pressurization steps, and two blocks 1145, 1150 corresponding to first and second separation steps, other examples of the method illustrated by process flow diagram 1100 can have any number of mixing steps, pressurization steps, and separation steps, and the number of mixing steps, pressurization steps, and separation steps need not be equal.

Example 4: Representative Autothermal HTL Reactor

[0298] Adding oxygen or air to sludge (which is also referred to herein as “biomass slurry” and/or “feed”) comprising organic material under elevated temperatures and pressures can oxidize the organic material. The most common application of this process is known as wet air oxidation (WAO). Sludge is pressurized, heated, and then mixed with pressurized oxygen or pressurized air. Sludge can be economically heated by hot reactor effluent in a heat exchanger. A spontaneous combustion reaction occurring after the sludge is pressurized, heated, and oxidized produces CO2 and other gases, which are separated in a downstream vapor-liquid disengagement vessel. Heat is exchanged between relatively hot liquid product and the relatively cold sludge in the heat exchanger. Solids are then separated before the liquid product is released downstream.

[0299] The oxidation reactions occurring during the wet air oxidation process are exothermic, which allows the sludge to self-heat as it reacts with oxygen. Therefore, the oxidation rate accelerates as the sludge progresses through a wet air oxidation reactor (FIG. 12) due to the increasing temperature of the sludge. The temperature of the sludge as it enters the wet air oxidation reactor typically satisfies a minimum threshold temperature to initiate the wet air oxidation process. A typical minimum threshold temperature can be from 212 °F to 482 °F (100 °C to 250 °C). The minimum threshold temperature can be achieved the various heaters, heat exchangers, and mixing vessels disclosed throughout this application.

[0300] The temperature increase across the wet air oxidation reactor provides energy to heat the incoming sludge. Tn certain embodiments, the magnitude of the temperature increase across the wet air oxidation reactor can be in a range from 122 °F to 302 °F (50 °C to 150 °C). When heat from the temperature increase is recovered downstream of the wet air oxidation reactor, the captured heat can heat the incoming sludge to the minimum threshold temperature. Under these conditions, the wet air oxidation process is an “autothermal” process because the process is thermally self-sustaining. Thus, under such conditions, the wet air oxidation reactor can be an autothermal reactor. Sludge oxidation in the wet air oxidation process is known to be autothermal when the sludge comprises at least 10% solids (e.g., biosolids) by weight.

[0301] FIG. 12 is a schematic diagram of a wet air oxidation reactor system 1200, according to one example. The wet air oxidation reactor system 1200 can comprise a sludge holding tank 1202, a heat exchanger 1230 disposed downstream of the sludge holding tank 1202, a wet air oxidation reactor section 1260 disposed downstream of the heat exchanger 1230, an oxygen stream 1265 disposed upstream of the heat exchanger 1230, a gas-liquid disengagement vessel 1280 disposed downstream of the heat exchanger 1230 and the wet air oxidation reactor section 1260, and a solidliquid disengagement vessel 1296 disposed downstream of the gas-liquid disengagement vessel.

[0302] The sludge holding tank 1202 can be configured to hold sludge entering the wet air oxidation reactor system 1200. The sludge comprises at least 10% solids by weight. The sludge holding tank 1202 can be further configured to heat the sludge. The sludge can leave the sludge holding tank 1202 via a first sludge stream 1204 from a bottom portion of the sludge holding tank 1202.

[0303] The oxygen stream 1265 can join the first sludge stream 1204 to form a second sludge stream 1222. In the illustrated example, the oxygen stream 1265 and the first sludge stream 1204 intersect at a location upstream of the heat exchanger 1230. However, the oxygen stream 1265 and the first sludge stream 1204 can intersect at any suitable location.

[0304] The heat exchanger 1230 can be configured to heat the second sludge stream 1222 to at least the minimum threshold temperature. The second sludge stream 1222 can enter a cold side of the heat exchanger 1230. Heat can be transferred from a hot side (e.g., a shell side) of the heat exchanger 1230 to a cold side (e.g., a tube side) of the heat exchanger 1230. Heating the second sludge stream 1222 can result in a third sludge stream 1262. The third sludge stream 1262 can exit the heat exchanger 1230 heated to at least the minimum threshold temperature.

[0305] The wet air oxidation reactor section 1260 can be configured to receive the third sludge stream 1262 and convert the third sludge stream 1262 into a first product mixture stream 1264. The third sludge stream 1262 can undergo the autothermal wet air oxidation process within the wet air oxidation reactor section 1260. In certain embodiments, the operating temperature of the wet air oxidation reactor section 1260 can be from 482 °F to 644 °F (250 °C to 340 °C), such as from 500 °F to 608 °F (260 °C to 320 °C). In certain embodiments, the operating pressure of the wet air oxidation reactor section 1260 can be from 275 psig to 2,160 psig (2 MPa to 15 MPa). In certain examples, the residence time of the sludge in the wet air oxidation reactor section 1260 can be from 0.25 hours to 2 hours.

[0306] The heat exchanger 1230 can be further configured to recover heat from the first product mixture stream 1264. The first product mixture stream 1264 can enter the hot side of the heat exchanger 1230 and heat is transferred from the hot side to the cold side of the heat exchanger 1230. Recovering heat from the first product mixture stream 1264 can result in a second product mixture stream 1273.

[0307] The gas-liquid disengagement vessel 1280 can be configured to separate gas from the second product mixture stream 1273. The separated gas exits the gas-liquid disengagement vessel 1280 for treatment. Separating gas from the second product mixture stream 1273 can result in a third product mixture stream 1275.

[0308] The sludge holding tank 1202 can be further configured to recover heat from the third product mixture stream 1275 to heat the sludge retained in the sludge holding tank 1202. Recovering heat from the third product mixture stream 1275 can result in a fourth product mixture stream 1294.

[0309] The solid-liquid disengagement vessel 1296 can be configured to separate liquids from the fourth product mixture stream 1294. The liquids, which constitute the effluent or the product of the wet air oxidation reactor system 1200, can exit a top portion of the solid- liquid disengagement vessel 1296. The solids, which constitute a byproduct of the wet air oxidation reactor system 1200, can exit a bottom portion of the solid-liquid disengagement vessel 1296.

[0310] Supercritical water oxidation (SCWO) is another type of autothermal reaction for processing sludge. Supercritical water oxidation occurs at temperatures and pressures above the critical point of water of 705 °F (374 °C) and 3,200 psig (22.2 MPa). [0311] FIG. 13 is a schematic diagram of a supercritical water oxidation reactor system 1300, according to one example. The supercritical water oxidation reactor system 1300 can comprise a sludge source 1302 (which is also referred to herein as a “biomass slurry source” and/or a “feed source”), a pump 1320 disposed downstream of the sludge source 1302, a heat exchanger 1330 disposed downstream of the pump 1320, an oxygen source disposed downstream of the heat exchanger 1330, a supercritical water oxidation reactor section 1360 disposed downstream of the heat exchanger 1330, a cooler 1367 disposed downstream of the heat exchanger 1330 and the supercritical water oxidation reactor section 1360, a pressure letdown section 1370 disposed downstream of the cooler 1367, and a gas-liquid disengagement vessel 1380 disposed downstream of the pressure letdown section 1370.

[0312] The pump 1320 can be configured to pressurize sludge received from the sludge source 1302. In certain examples, the pressure of the pressurized sludge can be from 3,600 psig to 3,900 psig (24 MPa to 27 MPa), 3,700 psig to 3,850 psig (25 MPa to 27 MPa), or 3,750 psig to 3,800 psig (26 MPa to 26.3 MPa). The heat exchanger 1330 can be configured to receive pressurized sludge from the pump 1320 and transfer heat to the pressurized sludge. The pressurized sludge can be received by a cold side of the heat exchanger 1330 and can be heated to a temperature of 480 °F to 575 °F (250 °C to 300 °C) by the heat exchanger 1330. The oxygen line 1365 can be configured to mix oxygen with pressurized, heated sludge leaving the cold side of heat exchanger 1330.

[0313] The supercritical water oxidation reactor section 1360 can comprise a tubular array reactor 1368 configured to convert the pressurized, heated sludge to a product mixture. The tubular array reactor 1368 can comprise an array of one or more tubes. Oxidation of the pressurized, heated sludge can take place within the one or more tubes. The temperature of the oxidized sludge subject to the supercritical oxidation process can be from 930 °F to 1,295 °F (500 °C to 700 °C), such as 1020 °F to 1,205 °F (550 °C to 650 °C), or at 1,112 °F (600 °C) as it is converted into the product mixture. Under these conditions, the supercritical oxidation process can be an “autothermal” process because the process is thermally self-sustaining. Thus, under such conditions, the tubular array reactor 1368 can be an autothermal reactor.

[0314] The heat exchanger 1330 can be further configured to recover heat from the product mixture exiting the supercritical water oxidation reactor section 1360. The product mixture can flow through a hot side of the heat exchanger 1330. Heat can be transferred from the hot side to the cold side of the heat exchanger 1330. Product mixture can leave the hot side of the heat exchanger 1330 to be further cooled by the cooler 1367. [0315] Product mixture leaving the cooler 1367 can be depressurized in the pressure letdown section 1370. Depressurized product mixture can be received by the gas-liquid disengagement vessel 1380. The gas-liquid disengagement vessel 1380 can be configured to separate the product mixture into a gas portion and a liquid portion. The gas portion can comprise off gas (including, but not limited to CO2, O2, and N2) constituting byproducts of the supercritical water oxidation process. The liquid portion can comprise biocrude constituting the product of the supercritical water oxidation process.

[0316] FIG. 14 is a schematic diagram of an autothermal HTL reactor system 1400 comprising an autothermal HTL reactor section 1460, according to one example. Some aspects of the autothermal HTL reactor system 1400 can be similar to other HTL reactor systems (such as HTL reactor systems 300, 500, 600) disclosed throughout this application. Thus, the autothermal HTL reactor system 1400 is illustrated as having many similar components as HTL reactor system 600. For example, the autothermal HTL reactor system 1400 can comprise the low pressure HTL section 601 and the first pressure letdown valve 670 of the HTL reactor system 600.

[0317] One exemplary difference between the autothermal HTL reactor system 1400 and nonautothermal HTL reactor systems is that the autothermal HTL reactor section 1460 of the high pressure HTL section 1403 can be configured to facilitate the wet air oxidation process described in connection with FIG. 12, the supercritical water oxidation process described in connection with FIG. 13, or any other oxidation process that reduces the amount of heat needed to operate the autothermal HTL reactor system 1400. Facilitating such reactions can beneficially decrease the energy input requirements of the HTL process by using oxidation to increase the sludge temperature across an autothermal HTL reactor, reducing the pressure of effluent exiting the autothermal HTL reactor, and transferring heat from vaporized water and gas byproducts generated by the pressure reduction to incoming sludge entering the autothermal HTL reactor.

[0318] To facilitate autothermal oxidation reactions, the autothermal HTL reactor section 1460 can comprise an oxygen line 1465, an oxygen compressor 1466, and an autothermal HTL reactor 1468. Oxygen from the oxygen line 1465 can be pressurized the by the oxygen compressor 1466. In some examples, the oxygen line 1465 can be configured to deliver oxygen in the form of air or other impure sources in which oxygen is combined with other gases (such as nitrogen, carbon dioxide, argon, water vapor, methane, light hydrocarbons, etc.). Pressurized oxygen can be mixed with biomass slurry in the autothermal HTL reactor 1468, thereby allowing oxidation reactions (such as wet air oxidation or supercritical water oxidation) to take place within the autothermal HTL reactor 1468. In the illustrated example, pressurized oxygen is introduced into the autothermal HTL reactor 1468 via one or more oxygen injectors 1469. As illustrated, the autothermal HTL reactor section 1460 comprises two oxygen injectors 1469. However, in other examples of the autothermal HTL reactor section 1460, the pressurized oxygen can be mixed with biomass slurry upstream of the autothermal HTL reactor 1468 using a mixing vessel, a mechanical mixer, a pipe fitting, or any other suitable assembly.

[0319] The autothermal HTL reactor 1468 can comprise a tubular vessel, container, pipe, and/or canister. The autothermal HTL reactor 1468 may comprise design features that help ensure oxygen is well-mixed with sludge such as baffles, mechanical mixers, etc. The autothermal HTL reactor 1468 need not include catalysts or complicated internals to facilitate the oxidation reactions.

[0320] The two oxygen injectors 1469 can be configured to inject oxygen at different points along the length of the autothermal HTL reactor 1468 to ensure good mixing of oxygen and sludge. The rate of oxygen injection can be controlled to meet the desired effluent temperature.

[0321] Non-autothermal HTL processes without oxygen injection typically generate CO2 as a byproduct gas, with CO2 comprising up to 5% by weight of HTL reactor effluent. Injecting oxygen for combustion generates additional CO2. The amount of required O2 for the oxidation reaction and the resulting amount of CO2 formation can depend at least in part on the heating value of the sludge entering the autothermal HTL reactor 1468 and which components of the sludge are oxidized. The reactor effluent CO2 concentration can increase to an estimated 9% to 45% CO2 by weight.

[0322] CO2 and other hot gases (such as water vapor, various non-condensable gases, and other HTL gas byproducts) can be separated from liquid effluent in vapor-liquid disengagement vessels 680 and 690 and bubbled through sludge in mixing vessels 610, 630 to recover heat. CO2 can leave the autothermal HTL reactor system 1400 with the other byproduct non-condensable gases in the offgas stream 618. The offgas stream 618 can comprise a high concentration of CO2, estimated at an 82% mass fraction or a 72% mole fraction, making carbon capture possible to improve the carbon intensity of HTL.

[0323] Another exemplary difference between the autothermal HTL reactor system 1400 and nonautothermal HTL reactor systems is that the autothermal HTL reactor system 1400 can further comprise an excess steam outlet 1435 disposed between the first vapor-liquid disengagement vessel 680 and the second mixing vessel 630. Excess steam generated by autothermal oxidation reactions in the autothermal HTL reactor section 1460 can exit the autothermal HTL reactor system 1400 and can be used by other systems or in other processes.

[0324] One exemplary difference between the autothermal HTL reactor system 1400 and other wet air oxidation reactor systems and the supercritical water oxidation reactor systems of FIGS. 12-13 is that the autothermal HTL reactor system 1400 uses steam heat recovery instead of heat exchangers to recover heat. As previously discussed, steam heat recovery can help reduce fouling on heat transfer surfaces, thereby beneficially increasing system reliability.

Example 5: Representative Sustainable Aviation Fuel (SAF) from Hydrothermal Liquefaction of Sewage Sludge

[0325] Hydrothermal liquefaction (HTL) can be a pathway to fuel for sewage sludge. HTL can be a conceptually simple (e.g., a heated pipe), scalable, and robust continuous process. HTL can accept a diverse range of wet feedstocks. In some examples, the wet feedstocks do not require drying. HTL can result in high carbon yields to liquid hydrocarbons. For example, HTL can result in up to 60% carbon yields. HTL can produce a gravity-separable, stable biocrude with low oxygen content. Tn certain examples, HTL can produce a biocrude with an oxygen content of 5%-l 5%.

[0326] A first step in an HTL process can comprise processing sludge in a HTL plant. The HTL plant can process 110 dry tons per day of plant sludge. HTL operating temperatures, pressures, and times can be 626 °F to 662 °F (330 °C to 350 °C), 2,900 psig (20.1 MPa), and 10-30 minutes, respectively.

[0327] A second step in the HTL process can comprise forming HTL biocrude. The HTL biocrude can be a stable biocrude. The HTL biocrude can have a 60% C-yield. The HTL biocrude can be gravity separable. The HTL biocrude can be thermally stable.

[0328] A third step in the HTL process can comprise processing the HTL biocrude in a hydrotreater. The HTL biocrude can be hydrotreated at 752 °F (400 °C) and 1500 psig (10.4 MPa). The hydrotreatment can be a “standard refinery unit-op.”

[0329] The HTL process can result in a hydrocarbon blendstock (which is also referred to herein as a “fuel blendstock”). The hydrocarbon blendstock can include, but is not limited to, any of diesel fuel, jet fuel, and naphtha. The hydrocarbon blendstocks can have a 95%+ C-yield. The hydrocarbon blendstock can predominantly comprise a high cetane diesel (70%).

[0330] The HTL plant can comprise three main process areas. The first process area can be a feedstock formatting and preparation (“prep”) area for preparing a pumpable slurry. The feedstock and/or pumpable slurry is sourced, transported, and/or formatted in this area. In some examples, the feedstock and/or pumpable slurry can be de-ashed in the feedstock formatting and preparation area. Issues that can be considered during feedstock formatting and preparation can include low- cost feedstocks and feedstock de-ashing. [0331] The second process area can be a liquefaction area where heat exchange and reaction take place. The second process area can have operating conditions of 662 °F (350 °C) and 3,000 psig (20.8 MPa). Issues that can be considered during liquefaction include reactor plugging, heat exchanger cost, blow-down life, and PFAS lifecycles.

[0332] The third process area can be a product separations area. The product separations area can involve the separation of oil, solids, and/or gas. The product separations area can include an oil/water separation set-aside. The product separations area can result in a clean oil/water separation during a run of the HTL process. Issues that can be considered during product separation include cold temperature properties of fuel, meeting marine specs, and N-removal/jet specs.

[0333] FIG. 15 is a chart showing a carbon balance breakdown 1 00 for a typical HTL experiment, according to one example. The HTL experiment can involve a regional wet waste blend. An exemplary 100 grams of carbon (C) can be processed into biocrude comprising 58 grams of carbon, a gaseous portion comprising 8 grams of carbon, an aqueous portion comprising

24 grams of carbon, and a solid portion comprising 10 grams of carbon.

[0334] The biocrude can comprise lights comprising 2 grams of carbon and fuel comprising 56 grams of carbon. The fuel can comprise jet fuel comprising 14 grams of carbon, diesel comprising

25 grams of carbon, gasoline comprising 9 grams of carbon, and heavies comprising 8 grams of carbon. Fuel testing can be critical for the jet fuel, diesel, gasoline, and heavies.

[0335] The gaseous portion can comprise carbon dioxide (CO2) comprising 6 grams of carbon, methane (CH4) comprising 0.5 grams of carbon, ethane (C2) comprising 0.1 grams of carbon, and heavier hydrocarbons (C3+) comprising 0.8 grams of carbon.

[0336] The aqueous portion can comprise oxygenates (“O”) comprising 5.7 grams of carbon and other compounds comprising 18 grams of carbon. The aqueous portion can be rich in oxygenates and nitrogen.

[0337] FIG. 16 is table 1600 illustrating chemical structures of several types of hydrocarbons present in feedstock, according to one example. Feedstock composition (such as hydrocarbon type, N content, and % aromatic content) can impact the resulting biocrude. In certain examples, the presence of fats 1610 can result in increased long n-alkane (cetane) content of the biocrude. In certain examples, lignins 1620 can result in increased aromatic content of the biocrude. In certain examples, proteins 1630 can result in increased N content of the biocrude. In certain examples, the proteins 1630 can form oil. In certain examples, cellulose 1640 can lead to increased C to aqueous phase. In certain examples, the cellulose 1640 can form oil in a Maillard reaction with protein. In certain examples, the cellulose 1640 can have a short carbon length with many oxygen atoms.

[0338] FIG. 17 is a graph 1700 comparing biocrude yields for multiple feedstocks (which are also referred to herein as “feed types”), according to one example. Wet wastes can have high carbon yields to biocrude. Increased natural digestion can result in lower carbon yields to biocrude. Biosolids with high ash can have much lower carbon yields.

[0339] FIG. 18 is a graph 1800 comparing product phase yields for multiple feedstocks, according to one example.

[0340] FIGS. 19A-C are graphs 1900a, 1900b, 1900c comparing fuel properties when upgraded, according to one example. Finished fuel can comprise a -70% high cetane diesel. All wet wastes can result a similar final fuel composition.

[0341] FIG. 20 is a chart 2000 comparing oxygen, nitrogen, sulfur, and heteroatom (TAN) contents of petroleum and biocrude, according to one example. Organic nitrogen can take two forms: amides 2010, which can be easily hydrogenated, and cyclic amines 2020, which can be more difficult to hydrogenate. Nitrogen content can be an issue if cracking is needed (cracking catalysts have acidic sites). The heteroatom content of petroleum into unit operations (after atmospheric distillation) is much lower. In certain examples, the heteroatom content is outside of what refiners are comfortable, so they dilute.

[0342] FIGS. 21A-21C are charts 2100a, 2100b, 2100c illustrating compositions of fuel samples from the hydrothermal liquefaction of wet wastes, according to one example. In certain examples, high-quality sustainable aviation fuel (SAF) can be produced from HTL of wet wastes. In some of these examples, 20-25% of upgraded fuel can be within in jet fuel range. SAF can comprise a similar mix of cycloalkanes, n-alkanes, iso-alkanes, aromatics as compared to traditional jet fuel. SAF can have positive alpha and beta jet fuel properties. A main concern can be the nitrogen in the SAF jet fuel. FIG. 21A is the chart 2100a illustrating distillation temperature versus percentage distilled of various components of SAF. FIG. 21B is the chart 2100b illustrating the percent mass of hydrocarbons based on carbon number. FIG. 21C is the chart 2100c illustrating SAF properties as compared to jet fuel specification ranges and limits.

[0343] FIG. 22 is a graph 2200 illustrating relative concentrations of N-containing species in an HTL biocrude feed as determined by comprehensive two-dimensional gas chromatography coupled with mass spectrometry (which is also referred to herein as “GCxGC MS”), according to one example. Biocrude can be rich in pyrazines, pyrroles, amides, indoles, etc. A significant amount of biocrude does not volatize in the column. One challenge for SAF is that SAF is expected to be <10 or <2ppm nitrogen. Another challenge is a concern that nitrogen-sulfur (N-S) interactions can lead to fuel instability issues in engines.

[0344] FIGS. 23A-23B illustrate residual nitrogen in SAF cut, according to one example. Both FIGS. 23A and 23B are graphs 2300a, 2300b of relative concentrations of N-containing species versus species type. The most challenging species to hydrotreat are the pyrroles, imidazoles, and pyrrolidines. Expect further HDN to get 2ppm N. Typical hydrotreating conditions can be -400 °C, 1500 psig (10.4 MPa), and 0.5 hr ¹ weight hourly space velocity (WHSV). Such hydrotreating conditions can result in a -97% nitrogen reduction.

[0345] FIG. 24 is a schematic diagram of a hydrothermal liquefaction system 2402 and a hydroprocessing system 2404, according to one example. Example considerations for HTL commercialization include:

• Aqueous Treatment (at HTL outlet 2408): Enable sustainable recycle.

• Improved HX (at heat exchangers 2410): Lower cost heat exchangers.

• Reactor Fouling (at HTL reactor 2414 and pump inlet 2406): Global correlation to predict fouling/plugging.

• Reactor Plugging (at HTL reactor 2414 and pump inlet 2406): Demonstrate 500-hour TOS without plugging.

• Strategic Feedstocks: Evaluate strategic wet-wastes.

• Low-Grade Feedstocks: Develop pathways for opportunity feedstocks and de-grid feedstock.

• Scale Up Testing: Campaigns in MHTLS.

• Oils from Solids (at HTL outlet 2408): Ensure solids can be land applied.

• Corrosion (at HTL outlet 2408): Material of construction compatibility.

• Solids Separation (at separator 2412): Engineering robustness.

• Blend Level Limits (at separator 2418): Decrease the impact of n-alkanes on the cold temperature properties of the fuel by isomerizing.

• Early Off-Take Version: Offtake partner for the biocrude.

• Efficient Guard Bed (at guard bed 2416): Prevent plugging and

• Catalyst Lifetime: Understand deactivation and/or demonstrate long TOS.

• Jet Fuel (at separator 2418): Reduce the N in the fuel to <10ppm, understand the N-S interactions on fuel thermal stability, and increase jet fraction to >65%.

• Fuel Stability (at separator 2418): Understand and address fuel stability. [0346] Any or all of the systems and processes described herein can provide a number of significant advantages over existing HTL systems and processes. For example, HTL reactor systems comprising mixing vessels and vapor-liquid disengagement vessels for steam heat recovery can be less prone to fouling than HTL reactor systems with heat exchangers which transfer heat across hot surfaces. Reducing the possibility of fouling can beneficially improve HTL reactor system reliability and can beneficially increase time intervals between maintenance events. Furthermore, steam heating can be relatively quick and can beneficially reduce the possibility of unwanted chemical reactions associated with high heat transfer temperatures over long heat transfer distances and the resulting longer residence times. Furthermore, injecting steam into mixing vessels can promote turbulent flow with better heat transport properties than laminar flow, which can beneficially improve heat transfer within HTL reactor systems. Finally, autothermal HTL reactors can generate excess heat which can be used to preheat incoming biomass slurry, which can beneficially decrease the amount of energy input into HTL reactor systems and increase the efficiency of the HTL reactor systems. Autothermal heating can improve the carbon efficiency of the HTL process by avoiding importing energy (such as natural gas) to heat the process. The fuel source is low cost (biosolids) and the CO2 resulting for the autothermal process is highly concentrated in an offgas stream, which aids carbon capture strategies.

Additional Examples of the Disclosed Technology

[0347] In view of the above-described implementations of the disclosed subject matter, this application discloses the additional examples enumerated below. It should be noted that one feature of an example in isolation or more than one feature of the example taken in combination and, optionally, in combination with one or more features of one or more further examples are further examples also falling within the disclosure of this application.

[0348] Example 1. A hydrothermal liquefaction (HTL) reactor system comprising: a biomass slurry source; a mixing vessel disposed downstream of the biomass slurry source, wherein the mixing vessel is configured to mix a biomass slurry stream received from the biomass slurry source with a vaporized water and gas byproducts stream; a pump disposed downstream of the mixing vessel, wherein the pump is configured to pressurize a biomass slurry stream received from the mixing vessel; a HTL reactor section disposed downstream of the pump, wherein the HTL reactor section is configured to produce a product mixture stream from a biomass slurry stream received from the pump; a pressure letdown valve disposed downstream of the HTL reactor section, wherein the pressure letdown valve is configured to reduce the pressure of a product mixture stream received from the HTL reactor section; and a vapor- liquid disengagement vessel disposed downstream of the pressure letdown valve, wherein the vapor-liquid disengagement vessel is configured to separate vaporized water and gas byproducts from a product mixture stream received from the pressure letdown valve, and wherein the separated vaporized water and gas byproducts form the vaporized water and gas byproducts stream received by the mixing vessel.

[0349] Example 2. The HTL reactor system of any example herein, particularly Example 1, wherein the HTL reactor section can comprise an autothermal HTL reactor.

[0350] Example 3. The HTL reactor system of any example herein, particularly any one of Examples 1-2, wherein the mixing vessel can be a first mixing vessel and the HTL reactor system can further comprise a second mixing vessel disposed downstream of the pump.

[0351] Example 4. The HTL reactor system of any example herein, particularly Example 3, wherein the second mixing vessel can be configured to provide a vaporized water and gas byproducts stream to the first mixing vessel.

[0352] Example 5. The HTL reactor system of any example herein, particularly any one of Examples 1-4, wherein: the pressure letdown valve can be a second pressure letdown valve, the vapor-liquid disengagement vessel can be a second vapor-liquid disengagement vessel, the HTL reactor system can further comprise a first vapor-liquid disengagement vessel disposed upstream of the second pressure letdown valve, and the HTL reactor system can further comprise a first pressure letdown valve disposed upstream of the first vapor- liquid disengagement vessel.

[0353] Example 6. The HTL reactor system of any example herein, particularly Example 5, which can further comprise an excess steam outlet coupled to an outlet of the first vapor-liquid disengagement vessel. [0354] Example 7. The HTL reactor system of any example herein, particularly any one of Examples 1-6, which can further comprise a heat exchanger disposed downstream of the HTL reactor section, and wherein the heat exchanger can be configured to recover heat from the product mixture stream.

[0355] Example 8. The HTL reactor system of any example herein, particularly Example 7, wherein: the heat exchanger can be a first heat exchanger in a heat transfer liquid circuit of the HTL reactor system, the heat transfer liquid circuit can further comprise a second heat exchanger disposed upstream of the HTL reactor section, and the heat transfer liquid circuit can be configured to circulate heat transfer liquid heated in the first heat exchanger to the second heat exchanger to heat a biomass slurry stream entering the HTL reactor section.

[0356] Example 9. The HTL reactor system of any example herein, particularly Example 8, wherein: the pressure of the biomass slurry stream entering the HTL reactor section can be a first pressure, the pressure of the heat transfer liquid circulating through the heat transfer liquid circuit can be a second pressure, and the first pressure can be higher than the second pressure.

[0357] Example 10. A hydrothermal liquefaction (HTL) process comprising: in a mixing vessel, mixing a biomass slurry stream with a vaporized water and gas byproducts stream to heat the biomass slurry stream; pressurizing a biomass slurry stream received from the mixing vessel; flowing the biomass slurry stream through a HTL reactor to produce a product mixture stream including biocrude oil and water; and in a flashing process, reducing the pressure of the product mixture stream to produce the vaporized water and gas byproducts stream.

[0358] Example 11. The HTL process of any example herein, particularly Example 10, wherein: the vaporized water and gas byproducts stream can be a first vaporized water and gas byproducts stream, the process can further comprise, after pressurizing the biomass slurry stream but before flowing the biomass slurry stream through the HTL reactor, mixing the biomass slurry stream with a second vaporized water and gas byproducts stream in a second mixing vessel.

[0359] Example 12. The HTL process of any example herein, particularly Example 11, wherein mixing the biomass slurry stream with the second vaporized water and gas byproducts stream can form a third vaporized water and gas byproducts stream, and wherein mixing the biomass slurry stream with the first vaporized water and gas byproducts stream can further comprise mixing the biomass slurry stream with the third vaporized water and gas byproducts stream.

[0360] Example 13. The HTL process of any example herein, particularly any one of Examples 11-12, wherein: the flashing process can be a second flashing process occurring in a second vapor-liquid disengagement vessel, the process further can comprise, before the second flashing process, reducing the pressure of the product mixture stream in a first flashing process occurring in a first vapor-liquid disengagement vessel to produce the second vaporized water and gas byproducts stream, the product mixture stream subject to the first flashing process can be received from the HTL reactor, and the product mixture stream subject to the second flashing process can be received from the first vapor- liquid disengagement vessel.

[0361] Example 14. The HTL process of any example herein, particularly Example 13, wherein the first flashing process can vaporize 5% to 50% of water in the product mixture stream.

[0362] Example 15. The HTL process of any example herein, particularly any one of Examples 13-14, wherein the second flashing process can vaporize 10% to 30% of water in the product mixture stream.

[0363] Example 16. The HTL process of any example herein, particularly any one of Examples 10-15, which can further comprise removing offgas from the mixing vessel, wherein the offgas can comprise 25% to 45% CO2.

[0364] Example 17. The HTL process of any example herein, particularly any one of Examples 10-16, which can further comprise, before flowing the biomass slurry stream through the HTL reactor, transferring heat from a heat transfer liquid stream to the biomass slurry stream in a first heat exchanger.

[0365] Example 18. The HTL process of any example herein, particularly Example 17, which can further comprise, after flowing the biomass slurry stream through the HTL reactor: transferring heat from the product mixture stream to the heat transfer liquid stream in a second heat exchanger; and circulating the heat transfer liquid stream from the second heat exchanger to the first heat exchanger.

[0366] Example 19. The HTL process of any example herein, particularly any one of Examples 10-18, which can further comprise, concurrently with flowing the biomass slurry stream through the HTL reactor, injecting oxygen into the HTL reactor.

[0367] Example 20. The HTL process of any example herein, particularly Example 19, which can further comprise, in the flashing process, producing an excess steam stream.

[0368] The features described herein with regard to any example can be combined with other features described in any one or more of the other examples, unless otherwise stated. For example, any one or more of the features of one HTL reactor system can be combined with any one or more features of another HTL reactor system. As another example, any one or more features of one HTL process can be combined with any one or more features of another HTL process.

Additional Considerations

[0369] Similar reference numbers can refer to components with similar features. For example, certain embodiments of mixing vessels 310, 410, 510, 610, 710, 910, 1010, etc. can share certain similar features. In another example, certain embodiments of pumps 320, 520, 620, 720, 1020, etc. can share certain similar features. In a final example, certain embodiments of vapor-liquid disengagement vessels 380, 580, 680, 780, 980, 1080, etc. can share certain similar features.

However, it should be understood that these examples are not exhaustive, and any other components disclosed in this application that share reference numbers can potentially share certain similar features. Additionally, it should be understood that components of the various systems described herein including the systems of FIGS. 1-7, 9, 10, and 12-14 can be combined in various ways. For example, the autothermal HTL reactors described with reference to FIGS. 12-14 can be used in combination with any of the heat recovery systems and processes described herein.

[0370] In view of the many possible embodiments to which the principles of the disclosed technology may be applied, it should be recognized that the illustrated embodiments are only examples and should not be taken as limiting the scope of the disclosure. Rather, the scope of the disclosure is at least as broad as the following claims and equivalents of the recited features. We therefore claim all that comes within the scope and spirit of these claims.