FIELD OF THE INVENTION

[0001] The invention relates generally to waste feedstocks conversion system and process. More particularly it relates to the field of feedstock-agnostic hydrothermal liquefaction process.

BACKGROUND OF THE INVENTION

[0002] Hydrothermal liquefaction is growing as an effective technology to efficiently valorize different types of feedstocks including biomass, organic solid wastes, plastics, industrial wastes and algae. With an increasing amount of solid waste generation in the world, many different technologies are being developed to treat them in a sustainable manner. It is the only thermochemical technique that can handle wet wastes containing upto 80-90% of moisture. Significant research into HTL has been conducted in batch systems, which has provided a fundamental understanding of the different process conditions and the performance of different feedstocks to produce liquid fuel. The requisites for a low-cost, commercial scale implementation of the process are essential in the current solid waste management system.

[0003] EP2718401B1 discloses that the feed mixture provided contains at least one homogeneous catalyst in the form of a compound of potassium and/or sodium so as to ensure a total concentration of potassium and sodium of at least 0.5% by weight for the process to convert at least part of the carbonaceous material. Whereas in our present invention there is no use of catalysts as the mixed solid wastes have different molecular groups and the interaction between those groups is self-sufficient to provide higher quantity and quality of crude. Also, the biocrude yield increment is not so great in large scale operations and not realistic. Apart from that the catalysts addition might add more cost to downstream processing, as they tend to change the pH of the reacting system, and also lead to accumulation of metal ions. However, the use of cheap solvents like waste cooking oil, motor oils can improve the bio-crude yield significantly.

[0004] Another patent SK288338B6 is focused on a system design which deals with thermal cracking of different organic material from specific and / or mixed wastes from used tires, plastics, paper, textiles, biomass and organic municipal waste in an inert atmosphere without the presence of air / oxygen. The patented reactor is based on the pyrolysis process where no water is used in the process and no liquefaction reaction is happening in the reactor. Whereas the present invention is typically a hydrous pyrolysis. It is a thermochemical depolymerisation process in an enclosed reactor to convert wet wastes and biomass into biocrude oil and chemicals at moderate temperature (typically 200-400°C) and high pressure (typically 10-25 MPa). Even the basic reaction chemistry of pyrolysis and hydrothermal liquefaction are very different.

[0005] An invention titled “Reactor for Continuously Treating Polymeric Material’ CN108883551B describes about the system for continuously processing recycled polymeric material. It includes a hopper configured to feed recycled polymeric material. This process is based on depolymerization of plastics and no hydrolysis is happening in the process.

[0006] CN 110368885B discloses about the method of biomass-based (particularly algae) biocrude oil preparation by continuous hydrothermal liquefaction processing. The flow pattern of algal slurry and solid waste slurry are different. Algae can be relatively easily homogenized in slurry form owing to the presence of lipids and extractable proteins in it. It is only proved in very small-scale volume (190 m ) and the scalability of system to a commercial model may be critical. A Continuous Stirred Tank Reactor (CSTR) is employed for processing biomasses. Whereas the present invention is a typical commercial model which is designed in such a way that it can handle most of the biomass and wide varieties of solid waste feedstocks with variable flow patterns up to 5 tons/day capacity and employs a Plug Flow Reactor (PFR) for seamless processing of solid wastes and biomasses.

[0007] Elliott, Douglas et al, US20180023003A1 relates generally to a combined hydrothermal liquefaction and catalytic hydrothermal gasification system and process for conversion of biomass to suitable chemical feedstocks for fuel production.

[0008] In an article titled “Establishment and performance of a plug-flow continuous hydrothermal reactor for biocrude oil production” (Ref link: doi.org/10.1016/j. fuel.2020. 118605), a similar kind of pumping system and a product separation system were reported. However, the reactor design doesn’t have any heat recovery system which will significantly influence the operational costs. Moreover, the reactor is designed for algae-based feedstocks with very low flow rate (0.54-7.2 L/h). This system may not be suitable for solid waste feedstocks which are used in our reactor system. [0009] In this article the major reactor engineering challenges including corrosion, precipitation of inorganic salts and char and coke formation in the reactor were discussed. In their reactor, a process with fast cooling of the product stream is straightforward. In addition, it was mentioned that it is possible to introduce organic liquids (108) such as ethanol into the downstream of the reactor to make the biocrude more stable and less viscous by blocking the reactive functional groups and cool down the product stream and quench unwanted reactions. The proposed model had a static mixer to mix hot water and biomass slurry. The mixed slurry goes into the reactor and flows into a flash tank through a cooler. This system seems to be good for limiting engineering issues in the reactor (Ref link: doi.org/10. 1016/j.biortech.2016.04.002). However, it is not proven at commercial scale and the present is a High quality nickel-based alloy is chosen at high temperature to limit the corrosion. The salt precipitation, char and coke formation issues are avoided by avoiding sharp angles and dead zones. The entire reactor tubing has constant diameter across the system. As ethanol is miscible with both water and crude, the addition of ethanol will complicate the products separation.

[0010] The above detailed of few research groups and ventures that have demonstrated the hydrothermal processing technology on a large scale. But all the demonstrated plants were able to handle only specific feedstocks. Moreover, the much-needed process of conversion of unsegregated municipal solid wastes and industrial wastes are not demonstrated in the form of a continuous processing model. Other thermochemical technologies like pyrolysis, gasification and combustion require pre-drying of wet feedstocks to limit the moisture content to 10-15% of the dry weight of the solids. To overcome the above drawbacks a feedstock-agnostic continuous scale hydrothermal liquefaction process is much needed for treating a variety of wastes.

OBJECTIVE OF THE INVENTION

[0011] The main objective is to develop an integrated pilot-scale model of continuous hydrothermal liquefaction (HTL) reactor for treating multiple feed stocks with better energy recovery for sustainable operations. [0012] Another objective of the invention is to improve the capability of handling and processing different types of waste feedstock slurries up to 25-30% loading in continuous flow reactor systems.

[0013] Further objective of the invention is to provide a significantly low-cost alternative commercial model, making it feasible for seamless scale-up.

SUMMARY OF THE INVENTION

[0014] A continuous hydrothermal liquefaction (HTL) reactor for treating multiple feed stocks including heterogeneous municipal solid waste, industrial waste, biomass, organic solid waste and plastics. The reactor will be a tubular/plug flow design to achieve maximum conversion of the feedstock to bio-crude along with maximum heat and energy recovery under high HTL temperature (upto 400C) and pressure (upto 300 bar). Due focus is also given to fluid flow and product separation, process intensification, heat integration and energy efficiency. The present invention is to improve the capability of handling and processing waste feedstock slurries up to 25-30% loading in continuous flow reactor systems to make progress towards energy recovery from abundant, low-cost municipal wastes, biomass, industrial wastes, plastics and mixed, co-mingled feed stocks.

[0015] This invention is related to the design of a continuous scale hydrothermal liquefaction plant is “feedstock agnostic” and can handle a wide variety of feedstock slurries including municipal solid wastes, industrial wastes, sewage sludge, agricultural residues, biomasses with better heat and energy recovery. The continuous scale plant is designed to treat a minimum of 5 tons (5000 kg) per day of mixed wastes containing bio-degradables (organic food wastes), industrial hazardous wastes, cellulosic wastes (paper, cardboard, and cloth), plastic packaging wastes, biomass-based wastes, and municipal solid wastes available in the landfills and dumpsites.

BRIEF DESCRIPTION OF DRAWINGS

[0016] The manner in which the proposed system works is given a more particular description below, briefly summarized above, may be had by reference to the components, some of which is illustrated in the appended drawing It is to be noted; however, that the appended drawing illustrates only typical embodiments of this system and are therefore should not be considered limiting of its scope, for the system may admit to other equally effective embodiments.

[0017] Throughout the drawings, the same drawing reference numerals will be understood to refer to the same elements and features.

[0018] The features and advantages of the present proposed system will become more apparent from the following detailed description along with the accompanying figures, which forms a part of this application and in which:

[0019] Fig 1: represents the continuous hydrothermal liquefaction (HTL) reactor for treating multiple feed stocks in accordance with our present invention;

REFERENCE NUMERALS

101 Shredding

102 Low pressure pumping

103 High pressure pumping

104 Feed transfer section

105 Main plug flow reactor

106 Product cooling section

107 4 Phase Separation Tank

107 a Gas

107 b Solids Slurry

108 Liquids

109 Two phase separation

109 a Bio Crude

109 b Aqueous Phase

110 Filtration

111 Bio-char

DETAILED DESCRIPTION OF THE INVENTION

[0020] Various embodiments and aspects of the disclosure will be described with reference to details discussed below. The following description is illustrative of the disclosure and is not to be construed as limiting the disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure.

[0021] A continuous hydrothermal liquefaction (HTL) reactor for treating multiple feed stocks incorporates (i) a novel pumping system to effectively pressurize the feedstock slurry (102 & 103), (ii) reactor section with pre-heater (104) and a plug flow reactor (105) to heat the reactants in stages, (iii) staged cooling followed by separation tank for seamless products separation and pumping, (iv) use of industrial waste water (treated or untreated) as a solvent and effective recirculation of the aqueous phase for better process intensification.

[0022] The continuous scale hydrothermal liquefaction unit design is claimed to ensure effective pump ability of solid waste feedstocks with a high solid loading (upto 40% dw) in HTL. This continuous pilot-scale HTL system could convert solid wastes into liquid crude with a capacity of atleast 1000 liters per hour of slurry feed or more. The reactor system is a continuous plug-flow reactor (PFR), which is selected because of the higher achievable heating rates. Heating of the contents of the reactor can be either using electric coils or gas or solar or biomass or coal or using the bio-char (111) generated during the processing of the feedstock in order to achieve better economic efficiency. The feedstock heating is achieved in two stages with a pre-heating section of SS 304 or SS 316 or SS 316L MOC to heat the feedstock upto 200-300°C, followed by a main heater section to increase the temperature further upto 350- 400°C. The reactor section or the main heater section can be made out of SS 304 or SS 316 or SS 316L or INCONEL 625 or HASTELLOY or MONEL. The major feedstocks which are essentially pumped in the system include municipal solid waste, biodegradable wastes, industrial wastes (includes waste gloves, rag, etc.) agricultural residues, lignocellulosic biomass, plastic packaging wastes, other cellulosic wastes (paper/cardboard), sewage solids, hazardous solids, and refuse derived fuels.

[0023] Such high solid loading will be possible owing to the significant presence of waste plastics in the slurry, which are hydrophobic in nature. The solid slurries are pumped continuously into the feed transfer section (104) in which the shiny is pre-heated. The preheated slurry shall further be heated in the main reactor section (105), and finally, it passes through feed transfer section heat exchanger (104) and product cooling section (106) to cool down the product slurry. The entire product slurry shall be fed into a phase separator tank where all gas (107 a), liquid crude, aqueous phase (109 b); char shall be separated from each other, and further transferred to storage tanks and downstream processing units.

[0024] The pumping of concentrated slurries at high pressure (103) will be performed. This will involve dual pistons operating in tandem. The heating of the feedstock is using either by electrical coils or gas or solar or biomass or coal or by burning the solid residue that are generated as a result of the HTL process. More importantly, the recycling of aqueous phase (109 b) after the reaction to make the feedstock slurry aids in process intensification thereby improving the product yields and their quality.

[0025] The present invention is a complete process train that can be packaged as a single pilot plant wherein the feedstock can be solid waste of any type, and the products will be bio-crude (109 a), solid residue, aqueous phase (109 b) and gases. The continuous flow reactor system consists of a feed tank, a primary pumping system consists of a low-pressure slurry pump (102), a secondary pumping system consists of high-pressure pumps (103) and cylinders, feed transfer section (104), main plug flow reactor tube (105), product cooling section (106), 4 phase separator cum settler tank (107), back-pressure regulator, sludge pump, heat transfer fluid circulation system and product tanks.

[0026] The HTL reactor may be designed to have an essentially constant cross section with an internal diameter throughout the full length of the tubular system or at least upto the main reactor section. There are two different types of pumps that are engaged to continuously pump the feedstocks at high pressure (102 & 103). The primary feeding system consists of a feed hopper and a slurry pump (102). The secondary pumping system consists of a high pressure pump (103), a double acting piston cylinder and a delivery cylinder which is capable of delivering high-viscosity materials, is used to achieve higher pressures from 250-300 bars. The secondary pump shall have two feeding piston cylinders, which tend to continuously operate one after another to push the slurry towards the feed transfer section (104).

[0027] The feed transfer section (104) can be a double pipe heat exchanger or a spiral heat exchanger or a shell-and-tube heat exchanger, which is designed to easily pump the solid slurries towards the main reactor section. Sharp angles of tubing bends are avoided to evade solids deposition. All tubes are designed to have flanged connection ends for better maintenance. In this heat exchanger the feed slurry and processed HTL slurry are flowing in counter current manner for efficient heat exchange avoiding the need of a separate heat transfer fluid. The preheated slurry from the feed transfer section flows through the main reactor section.

[0028] In the reactor section, feedstock slurry is heated to 350-40(1 C where the organic feedstocks are depolymerized to form four different fractions, viz., bio-crude (109 a), bio-char (111), aqueous phase (109 b) and gases (107 a). Here, provision is made to vary the residence time of the slurry by altering the inlet flow rate. Owing to the presence of pre-heating section, the heating rate of the feedstock is fairly rapid as it reaches the main reactor. The product cooling section ( 106) will be a secondary heat transfer section, which has a counter flow double pipe heat exchanger in which the hot HTL product stream flows in the inner tube and cold heat transfer fluid (Thermic fluids or water) flows in the outer tube. This section may also be an air- cooling type heat exchanger in which the hot slurry flows into an air-cooling tower or bed.

[0029] In the exit of the product cooling section (106) slurry pressure is reduced using one or more back pressure regulators or pressure control valves using single or multiple tubes. The back-pressure regulator(s) or pressure control valve(s) releases the pressure directly or indirectly in a continuous mode. Then, the slurry will is feed to the top (on side) of the separator tank. This separator tank is a closed tank which has a slow rotating stirrer on the top or on the side or on the bottom to agitate the solids. The stirrer may be a screw type or blade type or anchor type. There can be more than one separation tank for maximizing the recovery of the liquid bio-crude. This separator tank separates HTL products (water, bio-crude, gas and biochar) according to their density. By removing the gas from the liquids (108) and solids, the pressure in the system will be significantly reduced. The collected gas shall be stored in large gas bags or gas storage tanks for further testing and use. The liquid products, which are biocrude (109 a) and aqueous phase, settles in the middle of the tank. The bio-char (111) moves down to the bottom due to their high density.

[0030] Heat transfer fluid circulation system will consist of a circulation pump (which circulates either water or thermic fluid), a reservoir tank and a flow meter. The heat transfer fluid flows from the circulation pump to recover the heat from the product mixture in product cooling section (106). Heat transfer fluids, which possess high thermal conductivity with low vapor pressure at high temperature, may be used for better heat recovery. The temperature at the inlet and outlet of this section will be in the range from 30-45°C. [0031] All parts in the system are integrated and controlled with advanced instrumentation and control units to achieve the desired output. The major instrumentation system includes thermocouples, pressure transducers, gas flow switch, control panel and cables. The solenoid valves in the tube line are precision made with pneumatic actuator control to handle high temperature and pressure in the unit. All these valves are driven by air. To drive these valves, an air compressor shall be used. Thermocouples are included in the feed transfer section (104) (in the start and end of heat exchanger tubes), the main reactor section (within the start, middle, and end zones of the PFR), the product cooling section (106) (in start and end of heat exchanger tubes), 4-phase separator tank (bottom of the tank). The thermocouples in the main reactor tube are connected to micro-controllers and solid-state relays for programming of the heaters. In addition to the pressure transducers, regular pressure gauges are used at the outlet of the slurry pump, at the inlet of the high-pressure pump cylinder, outlet of the feed transfer section (104), at the end of main reactor tube section, beginning and end of product cooling section (106), and at the top of the 4-phase separator tank.

[0032] This continuous HTL reactor is a low-cost alternative, making it feasible for scaling up. The reactor system is a continuous plug-flow reactor (PFR), which is selected because of the higher achievable heating rates and better conversion for positive order kinetics that is typical in HTL. The double tube (inner tube paced in a reactor) design allows the cold solid waste feed entering through the inner tube to be pre-heated. The entire heat in the process is recovered and transferred to the feed by circulating heat transfer fluid in the annular pipe.

[0033] The HTL reactor may be designed to have an essentially constant cross section. All parts exposed to process media at temperatures higher than ~ 250°C may be constructed from a high-grade nickel alloy (like INCONEL 625 or Hastelloy) or SS 316 or SS 316L. One of the biggest advantages of nickel-alloy pipes is that they are incredibly resistant to several different types of corrosion. High-performance nickel alloys like Inconel 625 are also resistant to reducing media, aggressive chemicals and seawater. In the low temperature parts (<250°C), all tubes, components including valves and cylinders are made of either SS316L or SS316 or SS 304. The process flow chart of the pilot-scale continuous flow reactor (CFR) system for high pressure, high-temperature hydrothermal liquefaction is illustrated in Fig. 1. [0034] The feedstocks are first grinded in a shredder (101), while fibrous agricultural residues are pulverized in the chaff cutter, and the particles with size range from 5 mm to 25 mm are obtained. Suitable cutting tool can be used to reduce the particle size of plastic packaging materials. These are then mixed with water (mostly industrial waste water or sea water or oilladen water) in a ratio of 1:3 to 1:5 (feedstock: water). The mixture will then be transferred to the mixing section and forwarded to feeding pump.

[0035] Generally, many of the biomass or waste particles in the feedstock slurry either settle at the bottom of the tank (high density waste, for example municipal wastes) or float on the top of the water (low density wastes, for example agricultural residues, plastics). It is advised to make the solids suspended in the liquid medium for better pumping. To attain this a cheap emulsifiers like waste cooking oil, flocculants (synthetic polymers) or HTL biocrude (109 a) may be mixed to improve the solids suspension in the water. This will also improve the pumping efficiency by evenly distributing the solids in the feedstock mixture. The mixing of cooking oil and biocrude (109 a) shall not be more than 5-10 wt.% of feed slurry.

[0036] Feeding system: There are two types of feeding systems in the unit viz., primary and secondary feeding systems. Two different types of pumps are engaged in the process to continuously pump the feedstocks at high pressure. The primary feeding system consists of a feed hopper and a slurry pump (which can be a progressive cavity pump or a screw pump or a sludge pump).

[0037] The first pump is a slurry pump and is also may be used to provide continuous recirculation of the shiny in the hopper, in order to ensure the homogeneity of the shiny and minimize settling of the feed slurry. It also provides a steady flow to the second pump at a slightly high pressure (~ 2 bars). This slurry pump is designed to carry solid loading up to 20% (of biomass) with a capacity of 1000-3000 liters per hour or even more. For every purge, the pump will fill the piston cylinder volume of 200-500 liters or more.

[0038] The secondary pumping system may consist of a high-pressure pump (which can be a high pressure jet pump or a high pressure piston pump or a hydraulic press power pack or a plunger pump), a double acting piston cylinder and a delivery cylinder or a combined cylinder. This is the main high-pressure feeding mechanism to feed the slurry into the reactor. A high- pressure piston pump or plunger pump, which is capable to deliver high-viscosity materials, is used to achieve higher pressures of 250-300 bars. Typically, this pump can deliver pressures of up to 400 bar or more and flow rates of up to 1000 liters per hour or more. In a typical run, a flow rate (as per the plant capacity) and a pressure of 100 - 300 bars may be used. The feed flow rate determines the number of strokes of the pump over the process.

[0039] The piston cylinder is a double acting one that moves forward and backward by hydraulic pressure. This piston is connected to the delivery cylinder with the piston rod. The piston rod knobs are made of solid steel with leak proof seals. Before pressurizing the piston cylinder, the delivery cylinder is filled with feedstock slurry by slurry pump. During this filling stage, the outlet valve and vacuum release in the delivery cylinder are closed. As soon as the slurry is filled inside the cylinder, the feed line valve and vacuum release valve are closed (while the outlet valve is open), and the high pressure pump starts to pump the slurry. Instead of having a straight joint, an angular joint may be used in the feed line from slurry pump to avoid clogging. The two sets of high-pressure pumps shall work in series to continuously feed the slurry into the reactor.

[0040] As described earlier, the pumping of high solid slurries is one of the critical aspects in the feeding section. There is a chance of choking if sharp edges are involved in pumping tube joints. To avoid this, a ‘Y’ joint or angular ‘T’ joint is engaged to connect two delivery cylinders with the feed transfer section (104) reactor tube. The flow field in the junction is complicated due to the ripple property of slurry flow velocity and pressure. During the design, the flow fields of T-junction and Y-junction will be analyzed using shear stress transport models, and will be optimized for better pumping.

[0041] Feed transfer section (104): The feed transfer section (104) is designed to easily pump the municipal solid wastes and plastics into the main reactor section. Sharp angles of tubing bends are avoided to evade solids deposition. All tubes are designed to have flanged connection ends for better maintenance.

[0042] The feed transfer section ( 104) is a heat exchanger where feedstock slurry flows in the inner tube and the product slurry flows in the outer tube. The feed heat exchanger tubes can be of SS 316 or SS 316L or SS 304 MOC. The heat transfer fluid (if used), which recovers the heat from HTL products in the product cooling section (106) goes to a chiller or a cooling tower. [0043] A mild hydrolysis temperature of 200-250°C is recommended for the pre-heater to prevent severe liquefaction reactions from occurring before the PFR. The final temperature at the exit of the feed transfer section (104) will be in the range of 200-300°C. The heat transfer fluid that flows back to the circulation pump tank will have temperature range of 30-50°C. The Inside Diameter (ID) of the inner tube is 4 -24 inches and thickness of the tube shall be properly designed to hold up the pressure. The ID of outer tube in the heat exchanger is 4-24 inches. Both feed transfer section (104) and product cooling section (106) are insulated to avoid thermal loss.

[0044] Main reactor section: In the reactor section, feedstock slurry is depolymerized to form four different fractions as bio-crude (109 a), bio-char (111), aqueous phase (109 b) and gas (107a). The main reactor section in the unit has a main reactor tube, a heater (which can be an electrical band heater or a gas fired heater or an oil heater or a solar powered heater or a coal fired heater or a biomass fired heater), a back-pressure regulator (if required) and rupture disc with flanged end connections. The design temperature and pressure of this section will be 400°C (or more) and 300 bar (or more). The entire reactor is completely insulated to avoid thermal loss. The reactants in this section are very much corrosive to the metal in contact. The faster heating rate is designed to be 50-200°C/min in the main reactor section using the heater. According to the estimated physical properties of the feedstock slurry, ceramic band heaters shall be used to supply heat for the PFR. There may be two or more safety elements engaged in the reactor section which are back-pressure regulator and rupture disc. They are connected just before the end of the reactor tube with flanged tube connection. The back-pressure regulator pressure may be set in the range of 150-250 bar according to the operating temperature and pressure. When the pressure in the system increases above this set pressure, this valve releases some of the slurry in the reactor to the emergency collection tank and maintains the pressure in the reactor within the operating range.

[0045] The designed temperature and pressure of the rupture disc may be 400°C (or more) and 300 bar (or more). The rupture disc in the system pops out during sudden extreme pressure development in the reactor. The exit of the rupture disc line is connected to the emergency collection tank or vessel. Generally, this emergency collection tank has a cooling coil circulation to cool the reactants immediately. The volume of this tank is typically double (or even more) the volume of entire volume of materials in all the sections of the reactor unit. Clogging can result in the rupturing of one disc, the consequences of which are limited to a loud noise. Periodic replacement of the rupture disc and the cleaning of the outlet tubing and collection tank are highly recommended to prevent injury and damage. There will be a manual ball valve to isolate these safety lines and to perform maintenance activities on a regular basis. The outlet of rupture disc will be plumbed (with gentle curving shapes) to a stainless-steel tank, so that the flow of hot and pressurized slurry can be safely handled.

[0046] Product cooling section (106): The product cooling section (106), has a counter flow double pipe heat exchanger in which the hot HTL product stream flows in the inner tube and cold heat transfer fluid flows in the outer tube. It is designed to carry high solid loading and bio-crude oil safely and efficiently. The bio-char (111) particles can easily get settled down in dead zones and edges, which can influence the pressure development in the reactor section. So, the tubing for product stream shall be properly designed without bends and edges.

[0047] The temperature of the product mixture at the end of the heat exchanger will be 35- 50°C. Both inner and outer tubes in the heat exchanger will be made of SS 316 metal or SS 304. Both the inner and outer tubes shall have adequate thickness to resist the pressures from both the fluids. The length of the tubes shall be fixed on the basis of thermal conductivity and flow rate of the heat transfer fluid. In the case of air-cooled heat exchanger, air may be flowed using fans towards the reactor tubes. Reactor tubes may or may not have fins around the tube.

[0048] 4 Phase Separator cum Settler (107): The exit of the product cooling section (106) is fed at the top (on side) of the separator tank. This separator tank is a closed tank which may have a slow rotating stirrer to mildly agitate and accelerate the settling of the solids. This separator tank separates HTL products (water, bio-crude, gas and bio-char) according to their density. There can be one separation tank to separate the HTL products in the end of the process. But, positioning multiple separation tanks in parallel can result in seamless product separation. The volume of the tanks can be equal or more than the slurry processing capacity of plant in a day.

[0049] The gas stream which is lightest in the product mixture is continuously collected from the top collection line. A filter membrane shall be utilized to filter out the dust and particulates. By removing the gas from the liquids (108) and solids, the pressure in the system will be significantly reduced. The collected gas shall be stored in large biogas bags (made of polymeric films) or gas storage tanks for further testing and use. Provision may be made to flare the gases through a chimney as and when the concentration of methane and other light hydrocarbons increases in the gas mixture based on continuous monitoring. The liquid products in the product which are bio-crude and aqueous phase settles in the middle of the tank. The bio-char (111) settles to the bottom due to its high density.

[0050] The tank, which has two level switches at different heights, will allow the draining of liquids (108) and solids. The liquid stream consisting of bio-crude and aqueous phase then goes through a 2 phase separating column (109) which separates the organic-laden aqueous phase and bio-crude by density difference. The solid slurry settled in the bottom of the tank will be pumped to a fdter press to squeeze the surface laden organics in the bio char. (I l l) The collected organics may be mixed with bio-crude or can be recirculating to the feed processing section.

[0051] In some embodiments, separation of biochar (111) is difficult once the char mixture has heavy bio-crude oils and forms a thick layer of asphalt-like cake with the char particles. In this case, the solids slurry (107 b) will be mixed with solvents like dichloromethane or hexane to extract the bio-crude. In the filtration unit (110) the filter may have a pore size of 5-50 micron.

[0052] Heat transfer fluid circulation system: Heat transfer fluid circulation system consists of an oil circulation pump, a reservoir tank and a flow meter. The pump is designed to deliver the heat transfer fluid or water at a rate of 100 - 1500 L/min. The heat transfer fluid flowing from the oil circulation pump recovers all the heat from the product mixture, which will be directed to the feed transfer section (104) to heat the feedstock slurry. Heat transfer fluids which have high thermal conductivity with low vapor pressure at high temperature may be used for better heat recovery. The temperature at the inlet and outlet of this section shall be in the range from 15-60°C.

[0053] Instrumentation: Instrumentation in the main reactor section shall include thermocouples, pressure transducers, gas flow switch, control panel and cables. The solenoid valves in the tube line are precision made with pneumatic actuator control to handle high temperature and pressure in the unit. All these valves are driven by air.

[0054] Thermocouples are included in the feed transfer section (104) (in start and end of heat exchanger tubes), the main reactor section (in the beginning, middle, and end of the PFR), the product cooling section (106) (in the beginning and end of heat exchanger tubes), 4-phase separator tank (bottom of the tank). The thermocouples in the main reactor tube shall be connected with micro-controllers and solid-state relays for programming of the band heaters. Provision for sectional heating of the band heater shall also be provided so that different zones of the reactor tube can be heated at different rates based on the nature of the feedstock. In addition to the pressure transducers, regular pressure gauges shall be used in the CFR: The typical locations can be at the outlet of the progressive cavity pump, at the inlet of the high- pressure pump cylinder, at the outlet of feed transfer section (104), at the end of main reactor tube section, at the start and end of product cooling section (106), and at the top of the 4-phase separator tank.

[0055] The operating temperature can be increased upto 450°C in to harvest more liquid crude from the feedstock at supercritical conditions. The present invention HTL plant is powered with grid-based power. However, an HTL biochar (111) based power plant can also be installed and the entire HTL plant will be completely self-powered. The HTL biochar (111) produced from feedstocks will be more than sufficient to power the entire plant. In this scenario, the integrated HTL plant will become self-sustainable and become more cost effective both from capital and operational points of view. Hydrothermal liquefaction is a net energy positive process and one of the major benefits of this process is it only consumes 10%— 15% of the energy content of the feedstock resulting in an energy efficiency of 85%-90%. This process is feedstock agnostic and can take moisture loading upto 90% (or even more).

[0056] The Higher Heating Value (HHV) of liquid crude produced from HTL is much better than pyrolysis oil and the O/C ratio is significantly low. The HTL crude can be widely used in different applications including FCC feedstock at refinery, drop-in fuels production, polymer blends preparation, power generation and Fine chemicals production.

[0057] A significant fraction of the nitrogen and sulphur content in the feedstock is either dissolved in aqueous phase or trapped in the solid residue. Therefore, there will be no gaseous NOx and SOx emissions, which are typical of other thermochemical processes like combustion, pyrolysis and gasification. Due to the high-pressure environment, the greenhouse gases generation is very low than any other technologies. It is a Low cost continuous, high-pressure feedstock agnostic slurry pumping system with 4 Phase (107) HTL products separator tank. It is durable & long-lasting commercial scale plug flow HTL reactor section (105) with maximum heat recovery from the HTL products mixture. [0058] While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope of the invention as claimed.