CROSS-REFERENCES TO RELATED APPLICATIONS

[0001] The present disclosure claims the benefit of U.S. Provisional Patent Application No. 63/300,395, entitled “CARBON CAPTURE VIA KILN”, which was filed on January 18, 2022 and is incorporated herein by reference in its entirety.

BACKGROUND

[0002] Various industrial processes produce byproducts that are harmful to the environment or generally undesirable, which may include solids, liquids, gases, suspensions, and various combinations thereof. The production of cement, and other related materials such as lime or hydrated lime, produces significant amounts of carbon dioxide as a byproduct, which has been identified as undesirable for release into the atmosphere. Cement is one of the most widely used human-made materials today, and the global production of cement creates a large portion of the industrially generated carbon dioxide released into the atmosphere every year.

SUMMARY

[0003] The present disclosure provides systems and methods of operation thereof that capture carbon dioxide (CO2) and additional acidic gases such as sulfur dioxide (SO2) and hydrochloric acid (HCI) from industrial point-source locations containing such gases using calcium-based sorbents. The present disclosure more specifically provides a process that integrates carbon capture from point-source locations producing calcium-based products such as cement and lime/hydrated lime plants using calcium-based solid sorbents from the same raw material as the product. The captured CO2 is further processed into other products including liquid fuels, chemicals, and plastics or otherwise sequestered using various methods. Spent sorbent from the carbon capture process is re-integrated into the point-source. [0004] One embodiment of the present disclosure is a method, comprising: contacting flue gas from a kiln with a calcium-based solid sorbent in a first chemical reactor to produce a calcium-based precipitate and a lean gas with a lower concentration of carbon dioxide than the flue gas; separating the lean gas from the calcium-based precipitate at a first exit temperature of the first chemical reactor; heating the calcium-based precipitate in a second chemical reactor to produce carbon dioxide and calcium oxide; separating the carbon dioxide from the calcium oxide at a second exit temperature of the second chemical reactor; and reacting the calcium oxide with steam in a third chemical reactor to produce calcium hydroxide.

[0005] In various embodiments of the method, the calcium-based precipitate includes at least one of: calcium carbonate; calcium sulfate; calcium sulfite; and calcium chloride.

[0006] In various embodiments of the method, the flue gas includes: carbon dioxide; sulfur dioxide; and hydrochloric acid.

[0007] In various embodiments the method further comprises: purging at least one of: the calcium-based precipitate, after separating the lean gas from the calcium-based precipitate; the calcium oxide, after regenerating the calcium-based precipitate; and the calcium hydroxide, after reacting the calcium oxide with the steam; and introducing a fresh calcium-based sorbent to the first chemical reactor. After which, the method may further comprise: feeding the at least one of the purged calcium-based precipitate and the purged calcium oxide to the kiln as raw materials for producing one of cement or lime.

[0008] In various embodiments the method further comprises: generating electricity via a heat exchanger in the third chemical reactor powering a turbine. After which the method may further comprise: electrolyzing the carbon dioxide produced from the calcium-based precipitate into oxygen and carbon monoxide via the electricity; and supplying the oxygen and a fuel to the second chemical reactor or electrolyzing water into hydrogen gas and oxygen via the electricity; supplying the oxygen and a fuel to the second chemical reactor; and reacting the hydrogen gas with the carbon dioxide produced from the calcium-based precipitate to produce at least one of: a liquid fuel; a chemical reagent; and a plastic.

[0009] In various embodiments the method further comprises: supplying clinker produced by the kiln at a kiln exit temperature to the third chemical reactor.

[0010] In various embodiments the method further comprises: providing the carbon dioxide produced from the calcium-based precipitate to a carbon capture system configured to sequester the carbon dioxide into one of a liquid fuel, a chemical reagent, and a plastic.

[0011] One embodiment of the present disclosure is a system, comprising: a kiln; a first reactor, including a sorbent that includes calcium hydroxide, and configured to: receive flue gas from the kiln at a first concentration of carbon dioxide; produce a lean gas at a second concentration of carbon dioxide, lower than the first concentration; and produce a calcium-based precipitate from the flue gas and the sorbent; a second reactor, configured to: receive the calcium-based precipitate from the first reactor; and heat the calcium-based precipitate to produce carbon dioxide and calcium oxide; and a third reactor, configured to: react the calcium oxide received from the second reactor with steam in to produce calcium hydroxide receive the calcium oxide from the second reactor; and return a first portion of the calcium oxide to the first reactor.

[0012] In various embodiments, the system further comprises: a first purger, disposed between the first reactor and the second reactor, configured to selectively supply a first portion of the calcium-based precipitate to the second reactor and a second portion of the calcium-based precipitate to the kiln; a second purger, disposed between the second reactor and the third reactor, configured to selectively supply a first portion of the calcium oxide to the third reactor and a second portion of the calcium oxide to the kiln; and a third purger, disposed between the third reactor and the first reactor, configured to selectively supply the first portion of the calcium hydroxide to the first reactor and a second portion of the calcium hydroxide to a disposal system. In some embodiments, the system may further comprise: a first separator, disposed between the first reactor and the second reactor, configured to vent the lean gas to atmosphere and provide the calcium-based precipitate to the first purger; and a second separator, disposed between the second reactor and the third reactor, configured to supply the carbon dioxide to a carbon reprocessing system.

[0013] In various embodiments of the system: the carbon reprocessing system further comprises at least one of: a carbon monoxide converter, configured to convert carbon dioxide into carbon monoxide and oxygen, a hydrogen generator, configured to produce hydrogen and oxygen from water, an electrical generator connected to a heat exchanger included in the third reactor and configured to supply electricity to the carbon reprocessing system, or a multi-stage preheater disposed between the kiln and the first reactor, configured to reduce a heat of the flue gas by transferring the heat to raw materials fed into the kiln. In various embodiments, the carbon reprocessing system is configured to produce hydrocarbon compounds from the carbon dioxide generated by the second reactor. [0014] In various embodiments, the system further comprises: a hydrator heat exchanger, disposed in the hydrator and configured to convert liquid water into the steam using reaction heat within the hydrator.

[0015] One embodiment of the present disclosure is a carbon capture system, comprising: a calciner, configured to heat calcium carbonate to produce carbon dioxide and calcium oxide; a separator, configured separate the carbon dioxide from the calcium oxide and to provide to provide the carbon dioxide to a carbon reprocessing system; a hydrator, configured to: receive the calcium oxide from the separator; react the calcium oxide with steam to produce calcium hydroxide; and a carbonator, configured to: receive the calcium hydroxide from the hydrator; receive flue gas from a kiln at a first concentration of carbon dioxide; react the flue gas with the calcium hydroxide to produce a lean gas at a second concentration of carbon dioxide, lower than the first concentration and a calcium-based precipitate including carbon compounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying figures depict various elements of the one or more embodiments of the present disclosure, and are not considered limiting of the scope of the present disclosure.

[0017] In the Figures, some elements may be shown not to scale with other elements so as to more clearly show the details. Additionally, like reference numbers are used, where possible, to indicate like elements throughout the several Figures.

[0018] It is contemplated that elements and features of one embodiment may be beneficially incorporated in the other embodiments without further recitation or illustration. For example, as the Figures may show alternative views and time periods, various elements shown in a first Figure may be omitted from the illustration shown in a second Figure without disclaiming the inclusion of those elements in the embodiments illustrated or discussed in relation to the second Figure.

[0019] Figure 1 is a material flow diagram of a kiln with a five-stage preheater, according to embodiments of the present disclosure.

[0020] Figure 2A is a block diagram of a cyclical calcium-based carbon capture process, according to embodiments of the present disclosure.

[0021] Figures 2B is a block diagram of a once-through calcium-based carbon capture process, according to embodiments of the present disclosure.

[0022] Figure 3 is a block diagram of the integration of the carbon capture process with clinker used for carbon capture, according to embodiments of the present disclosure.

[0023] Figure 4A is a block diagram for integration of the carbon capture process with electricity generation and carbon dioxide electrolysis, according to embodiments of the present disclosure. [0024] Figure 4B is a block diagram for integration of the carbon capture process with electricity and hydrogen generation via electrolysis, according to embodiments of the present disclosure.

[0025] Figure 5 is a flowchart of an example method for gas capture from industrial point-sources, according to embodiments of the present disclosure.

[0026] Figures 6A-6D are flowcharts of example synergistic methods for use with methods for carbon reprocessing and carbon capture from industrial pointsources, according to embodiments of the present disclosure.

DETAILED DESCRIPTION

[0027] The present disclosure provides systems and methods of operation thereof that capture carbon dioxide (CO2) and additional acidic gases such as sulfur dioxide (SO2) and hydrochloric acid (HCI) from industrial point-source locations containing such gases using calcium-based sorbents. The present disclosure specifically provides a process that integrates carbon capture from point-source locations producing calcium-based products such as cement and lime/hydrated lime plants using calcium-based solid sorbents from the same raw material as the product. The captured CO2 is further processed into value-added products including liquid fuels, chemicals, and plastics or sequestered using various methods. Spent sorbent from the carbon capture process is re-integrated into the point-source.

[0028] The present disclosure synergizes the capture of carbon with the production of cement, lime, and related products. The synergy between the carbon capture process and cement/lime production process originates from the raw feed for both being identical, which allows for equipment to be shared, as the purge streams from the carbon capture process can become raw feed for cement/lime production, and the pre-processing and source of raw materials for both carbon capture and cement/lime production may be identical. Integrating a carbon capture process into a cement or lime plant can act as either a retrofit or greenfield design, with the greenfield plant potentially allowing for greater process integration options. [0029] In various embodiments, the captured CO2 is further processed into value-added products and reagents including liquid fuels, chemicals, and plastics. Additionally or alternatively, the capture CO2 (or resulting product) can be sequestered using various methods that will be known to those of ordinary skill in the relevant art. In some embodiments, spent sorbent from the carbon capture process is re-integrated into the cement plant as raw feed.

[0030] When producing liquid fuels from the captured CO2, the process controls for the ratio of Hydrogen (H2) to Carbon Monoxide (CO). The captured CO2 can be integrated into liquid fuels production processes with the requisite H2:CO mole ratio controlled by the reduction of CO2 to CO thermochemically using the Boudouard reaction, electrochemically through electrolysis, plasmatically through ionization, or other commercially-available processes for converting CO2 to CO through biological or hybrid chemical/biological routes.

[0031] Additionally or alternatively, H2 can be produced from within the process depending on process integration, operating conditions, degree of CO2 removal, and the end product generated from the captures CO2. In various embodiments, the H2 can be produced through the water-gas shift reaction, electrolysis, or reform ing/gasification of hydrocarbons.

[0032] The capture of CO2 from a cement or limestone plant uses a cyclic loop of calcium hydroxide (Ca(HO)2), calcium carbonate (CaCOs), and calcium oxide (CaO). The synergy between the cyclic carbon capture process and the cement or limestone production process affords for an energy-efficient, low-cost method to reduce or eliminate carbon emissions from the point-source. For carbon capture, Ca(HO)2 is included in a solid sorbent to form CaCOs through chemical sorption of CO2 from the kiln gas stream, which contains CO2 from the calcination of the CaCOs included in the limestone and the fuel combustion to attain the necessary temperatures. The reaction occurs at temperatures greater than 200 °C, which may be limited by heat transfer and reaction kinetics. The maximum temperature is dictated by the thermodynamic equilibrium between Ca(HO)2 and CO2 and the desired percentage for CO2 removal. The concentration of CO2 in the kiln gas stream depends on the fuel used for combustion, kiln type, and final product (e.g., lime or cement). The ratio of CO2 produced from limestone calcination is constant, where one mole of CaCOs produces one mole of CO2. For lower calcium limestones, such as dolime, one mole of CO2 is still produced from calcination as magnesium replaces an equivalent amount of calcium on a molar basis. The operating temperature is between 800 °C and 1200 °C. The minimum temperature is dictated by thermodynamics and reaction kinetics between CO2 and CaO. The maximum temperature is based on sintering, where high-temperatures reduce reactivity through reduction of pore space. The products include a CO2-lean gas stream and CaCOs. The CaCOs is calcined in an independent kiln using oxycombustion or indirect heating to produce CaO and a pure CO2 gas stream.

[0033] The CO2 is reduced to Carbon Monoxide (CO) for further processing into liquid fuels, chemicals, or hydrogen. The CaO reacts with steam to produce Ca(HO)2, which releases heat through the exothermic reaction. This heat can be used for heat exchange or coupled with a turbine and electrolyzer to produce H2. While hydration can occur at any temperature, for the exothermic heat to be recuperated for useful work, the minimum operating temperature is approximately 125 °C. While there is no theoretical maximum temperature, the reaction at atmospheric pressure is thermodynamically limited to 512 °C. This thermodynamic temperature limit can be overcome by increasing the reaction pressure.

[0034] Figure 1 is a material flow diagram of a kiln 110 with a five-stage preheater, according to embodiments of the present disclosure. The kiln 110 is provided fuel via a fuel intake 150 and air to combust with the fuel via an air intake 160 to produce clinker (e.g., incombustible residue which may be used as an intermediated product in the production of cement, lime, and related products) from raw material. The raw material is received via a meal input 140 that travels via a meal path 190 through a series of preheater stages 120a-e (generally or collectively, preheater stage or stages 120). Output gas from the kiln 110 travels through the series of preheater stages 120a-e via a gas path 180 to a gas exit 130. The gas travels countercurrently relative to the raw material through the preheater stages 120 to use the waste heat from the kiln 110 to preheat the raw material and reduce the temperature of the output gas ejected via the gas exit 130.

[0035] Although illustrated with five preheater stages 120a-e, in various embodiments the preheater may include more or fewer stages 120 with various changes in temperature between each stage. Accordingly, the gas may enter and exit each stage 120 at various temperatures (generally dropping as the gas approaches the gas exit 130), while the raw material generally increases in temperature while approaching the kiln 110. Depending on the fuel used for combustion in the kiln 110 and the pressure of the reaction and surrounding environment, the gas may exit the kiln 100 with various volumes of CO2 (e.g., between 10% and 35% CO2 by volume).

[0036] The kiln 110 may be used for producing cement, lime, or similar products, which are output via a clinker exit 170. For example, in a cement production process, limestone, shells, chalk, marl, shale, clay, iron ore, slag, and other materials may be provided as the raw material inputs to produce clinker (as an intermediate product) by sintering the provided raw material in the kiln 110. Various different blends of cements can be made by altering the composition of the raw materials and the temperatures at which the kiln 110 operates at. The process of sintering the raw materials into clinker requires significant heat via the combustion of the fuel, which releases CO2. Additionally, chemical changes in the raw materials also release CO2, which are included with various other gases in the flue gas.

[0037] Figures 2A and 2B illustrate carbon capture systems for use with one or more kilns 110 that are used for producing cement, lime, or similar products that release CO2 during a sintering process that is to be captured rather than released directly to the atmosphere. The carbon capture systems may be added to existing kilns 110 as retrofits, or may be produced with new kilns 110 as original equipment. [0038] Figure 2A is a block diagram of a cyclical calcium-based carbon capture process, according to embodiments of the present disclosure. Flue gas from a kiln 110 (e.g., as used in a cement or limestone plant) is initially fed into a carbonator 210. In various embodiments, the flue gas is cooled down using a heat exchanger, such as described in relation to Figure 1 , prior to being fed to a carbonator 210 or may be fed directly to the carbonator 210. In embodiments excluding the heat exchanger, the heat from the flue gas can be actively removed using an in-bed heat exchanger internal to the carbonator 210, such as those known in the chemical, petrochemical, and power industries.

[0039] The carbonator 210 is a chemical reactor or chemical reaction vessel in which Ca(HO)2 reacts with the CO2 in the flue gas at temperatures greater than 200 °C (e.g., between 300 °C to 700 °C for high CO2 removal and appreciable reaction kinetics). Additional acidic gases, such as sulfur dioxide (SO2) may also be included in the flue gas received from the kiln 110, which the carbonator 210 also reacts with the Ca(HO)2. It is assumed that the flue gas has excess oxygen (O2) present, thereby allowing for full oxidation of the SO2 to calcium sulfate (CaSO4); however, the carbonator 210 may also include an O2 intake to supplement the concentration of O2 in the flue gas.

[0040] In various embodiments, the carbonator 210 receives the flue gas after the flue gas has transferred heat to the raw material for the kiln 110 (e.g., from the gas exit 130 passing through the preheater stages 120a-e illustrated in Figure 1 ), or may receive the flue gas directly from the kiln 110 (e.g., omitting the preheater stages 120). Flue gas received directly from the kiln 110 is generally hotter than flue gas received from the preheater stages 120 (e.g., approximately 1000 °C versus approximately 300 °C). In embodiments that directly pass the flue gas from the kiln 110 to the carbonator 210, heat may be transferred to the raw materials input to the kiln 110 by routing the meal path 190 around the carbonator 210 or other heated or exothermic elements of the system.

[0041] The temperature in the carbonator 210 is dependent on the reactant inlet temperature, inlet material flow, and extent of reactions occurring inside the carbonator 210. Although the carbonator 210 can operate at various temperatures, it is generally advantageous to operate the carbonator 210 at higher temperatures to minimize temperature swings in the carbon capture process and to maximize process efficiency. Because the Ca(HO)2 exiting the hydrator 250 (when operated at approximately one atmosphere (atm) of pressure) is at a temperature less than 513 °C, and the reactions occurring inside the carbonator 210 are fixed based on the reactor design of the carbonator 210, the carbonator temperature can be controlled by controlling the temperature of the flue gas received from the kiln 110. Higher flue gas temperatures are attained by reducing of number of preheaters stages 120 or omitting the preheaters. Additional heat integration can include heating the feed path 190 using waste heat from the carbon capture process from heat exchangers used to cool the CO2-lean gas before release to the atmosphere, cool the CaO before purge or transfer to the hydrator 250, and cool the CO2 output before transferring to further processing or sequestration systems.

[0042] The reaction in the carbonator 210 produces a lean gas, with a lower concentration of CO2 than the initial flue gas, and a solid calcium-based precipitate from the reacted CO2 and other acidic gases in the flue gas and the calcium-based sorbent. In various embodiments, the exact concentration of CO2 in the lean gas may vary based on the initial concentration of CO2 in the flue gas, temperature in the carbonator 210, desired rate of throughput, the presence (and concentrations) of other acidic gasses in the flue gas, etc. In various embodiments, the solid calcium-based precipitates include CaCOs and other carbon compounds as well as one or more of CaSO4, calcium sulfite (CaSOs), and calcium chloride (CaCl2), in which the exact sulfurous calcium species (and relative concentrations thereof) formed in the solid precipitate by the carbonator 210 will depend on temperature and gas atmosphere present in the carbonator 210.

[0043] Various jurisdictions and entities may define what qualifies as a “CO2- lean” gas according to different standards and measurement techniques that the present disclosure may meet or exceed when producing the lean gas. For example, the United States Department of Energy (US DOE) defines removal of upwards of 90% of the inlet CO2 as producing a CO2-lean gas. In another example, the United States Environmental Protection Agency (US EPA) in the Clean Power Plan defines CO2-lean gas as the output of 1400 pounds of CO2 or less per Megawatt hour (lb CC /WMh) for coal-fired power plants and 100 lb CO2 per MWh for natural gas fired power plants. Additionally, when the carbon capture process captures more CO2 than the combustion or reaction outputs of the associated process (e.g., capturing CO2 from ambient air in addition to the combustion or reaction outputs), the process may be described as a carbon-negative process. Accordingly, the carbon capture process described herein may produce a lean gas with various relative levels of CO2 including 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 105%, and 110% relative to the CO2 levels in the corresponding input flue gas. Additionally or alternatively, the lean gas may be defined by the amount of CO2 produced per MWh of potential energy in the fuels used in the kiln 110 or chemical reaction vessels, or weight of product produced in the kiln 110 (e.g., cement of lime) according to various definitions.

[0044] The carbonator 210 outputs the CO2-lean gas to a first separator 220a (generally or collectively separator 220) for gas-solid separation. In various embodiments, the separators 220 include commercially available cyclone or inertial separators, electrostatic precipitators, baghouse collectors, and wet scrubbers. The first separator 220a separate the CO2-lean gas from the CaCOs solids, and outputs the CO2-lean gas to the atmosphere. In various embodiments, the CO2-lean gas is cooled through a heat exchanger prior to being released into the atmosphere. The CaCOs is output from the first separator 220a to a first purger 230a (generally or collectively, purger 230) to selectively remove accumulated inert species from the carbon capture process (e.g., for addition to the raw materials as feed stock for the kiln 110) or to provide the CaCOs (and other components of the precipitate or “dust”) to a calciner 240 for further processing.

[0045] In various embodiments, the purgers 230 include controllable conveyors, chutes, collection receptacles or the like, and may be integrated with a separator 220 or reaction vessel, or presented as a separate apparatus to control the amount of a product of an earlier stage provided to a next stage or that is removed from the CO2 capture process (e.g., for use as a raw material in the kiln 110 feeding the CO2 capture process). For example, the first purger 230a may provide all, some, or none of the solid precipitate (which contains CaCOs) to the calciner 240 for further use in the carbon capture process to allow for various amounts of fresh CaCOs (that includes lower concentration of the sulfurous calcium species present in the precipitate) to the calciner 240.

[0046] The calciner 240 is a chemical reactor or chemical reaction vessel in which the CaCOs is decomposed into CaO and CO2. Because the calcination reaction is endothermic and occurs at high temperatures, the calciner 240 may be an oxy-fired calciner in various embodiments. The calciner 240 may receive fresh CaCOs, use cycled CaCOs (e.g., received from the first separator 220a and first purger 230a), or combinations thereof, and is fed O2 to combust with a fuel. In various embodiments, the fuel may be any gaseous, liquid, or solid fuel, and mixtures thereof, which is combusted with substantially pure O2 to produce a substantially pure stream of CO2. Common fuels for the calciner 240 include, but are not limited to coal, coke, fuel oil, and natural gas. In some embodiments, the calciner 240 may be an indirectly-heated calciner that uses concentrated solar power or infrared heaters powered by electricity instead of fuel and oxygen, in which case the fuel and oxygen feeds may be omitted.

[0047] The precise operating temperature used by the calciner 240 is determined by the operator based on thermodynamics, reaction kinetics, desired throughput rate, and reactor design. At atmospheric pressure and substantially pure CO2, thermodynamically CaCOs will begin to calcine at approximately 900 °C; however, the temperature for the reaction can be reduced through methods such as dilution and pressure reduction. In some embodiments, steam is added to the calciner 240 as a diluent, but other diluents may be used so long as the diluent undergoes a phase change such that substantially pure CO2 can be recovered.

[0048] A second separator 220b separates the CO2 from the CaO received from the calciner 240, which may include various commercially-available gas-solid separation equipment that operate at calcination temperatures. The second separator 220b outputs the recovered CO2 for further processing to a carbon reprocessing system to produce liquid fuels, various chemicals, plastics, or to otherwise sequester the CO2. The second separator 220b provides the remaining CaO to a second purger 230b. If purged, the CaO can be mixed with the raw meal in the kiln 110. Since the CaO is already calcined and at calcination temperature, the inclusion of the remaining CaO can reduce the energy requirements of the kiln 110 to heat the raw materials. For example, in a lime production plant, the purged CaO can be added to the main lime product. Purged CaO can also be used to recover heat, as its initial temperature is the operating temperature of the calciner 240.

[0049] In various embodiments, the unpurged CaO from the calciner 240 is cooled via an external heat exchanger or is cooled within the calciner 240 (or the second separator 220b or purger 230b) where heat can be actively removed via an in-bed heat exchanger such as those that are commonplace in the chemical, petrochemical, and power industry. After being cooled, the CaO is fed into a hydrator 250. Because the reactions occurring in the hydrator 250 are highly exothermic, active in-bed heat exchange may already be present in the hydrator 250, and an independent heat exchanger is optional.

[0050] The hydrator 250 is a chemical reactor or chemical reaction vessel in which CaO reacts with steam to produce Ca(HO)2. Although liquid water is capable of forming Ca(HO)2 through reacting with CaO, the heat evolved from the exothermic reaction is of too low quality to be recuperated for useful work by other systems. Accordingly, in various embodiments, the hydrator 250 operates at temperatures greater than 125 °C (e.g., with gaseous water) to allow other systems to recuperate the heat for additional uses. The higher the operating temperature of the hydrator 250, the higher the quality of heat that can be recuperated for heat exchange. However, at one atmosphere (atm) of pressure and with steam at temperatures greater than 512 °C, thermodynamics prevents the hydration of CaO. Accordingly, the hydrator 250 may be configured in some embodiments to operate at pressures greater than 1 atm to increase the maximum operating temperature to use steam above 512 °C to hydrate the CaO to produce Ca(HO)2. [0051] In various embodiments, the hydrator 250 includes a hydrator heat exchanger 252 that receives liquid water and produces steam using the internal temperature of the hydrator 250 (and the ongoing exothermic reaction) to heat the liquid water into steam. The hydrator heat exchanger 252 may receive liquid water, supply the hydrator 250 with the steam used for the hydration reaction, and provide additional or excess steam to the calciner 240 as a diluent.

[0052] The hydrator 250 feeds the produced Ca(HO)2 to a third purger 230c, which may optionally remove a portion of the Ca(HO)2 from the CO2 removal process (e.g., to prevent accumulation of inert species and allow for addition of fresh material), or feed the unpurged Ca(HO)2 back into the carbonator 210 for further processing.

[0053] Figure 2B is a block diagram of a once-through calcium-based carbon capture process, according to embodiments of the present disclosure. In contrast to the cyclical process illustrated in Figure 2A, the first purger 230a does not supply the processed CaCOs to the calciner 240, which instead uses fresh CaCOs rather than processed CaCOs or a mix of processed and fresh CaCOs.

[0054] In various embodiments, the process illustrated in Figure 2B may be performed as an initial or a terminal cycle of the cyclical process illustrated in Figure 2A to introduce the calcium-based sorbent to the carbonator 210 at the beginning of a production process or to prevent reuse of the sorbent after a predefined amount of time, number of cycles, or throughput (e.g., to reduce reintroduction of the sulfurous calcium precipitates to the calciner 240). Additionally or alternatively, the operator may perform the process illustrated in Figure 2B to avoid using processed CaCOs or to feed all of the processed CaCOs (and associated precipitates) back into the kiln 110 as reclaimed materials (e.g., via the meal input 140). Once a single cycle is completed, the CaCOs is mixed with the raw meal and enters the kiln 110. The single cycle reduces the amount of solids circulation in the carbon capture process and ensures that the sorbent is always fresh, as the fresh CaCOs does not undergo the typical reduction in reactivity towards CO2 that is exhibited of previously processed sorbents. [0055] Figure 3 is a block diagram of the integration of the carbon capture process with clinker used for carbon capture, according to embodiments of the present disclosure. As illustrated, a fraction of the clinker produced by the kiln 110 can be integrated into the carbon capture process to supplement the amount of fresh CaCOs or refreshed CaCOs provided to downstream systems by the calciner 240. In various embodiments, the clinker exit 170 may provide the clinker to the intake of the second separator 220b, the intake of the second purger 230b, or the intake of the hydrator 250 at a kiln exit temperature.

[0056] By using the already hot clinker received from the kiln 110, an operator may reduce the energy requirements of the calciner 240 used in the carbon capture process, albeit with reduced clinker output from the kiln 110.

[0057] Figures 4A and 4B show a portion of the system and process described in greater detail in regard to Figures 2A and 2B that focuses on processing the CO2 captured from the calciner 240.

[0058] Figure 4A is a block diagram for integration of the carbon capture process with electricity generation and CO conversion, according to embodiments of the present disclosure. In various embodiments, the CO2 captured by the calciner 240 is provided to a carbon monoxide converter 410. Many methods exist to convert CO2 to CO that can be used to produce liquid fuels, chemicals, or other products, and the carbon monoxide converter 410 is one example of a carbon reprocessing system (or a component thereof). The conversion can occur through plasma reactions, thermochemical reactions, catalytically, or electrolysis in the various designs of chemical reactors or chemical reaction vessels that are commercially available for use as carbon monoxide converters 410.

[0059] In some embodiments, the carbon monoxide converter 410 coverts the CO2 to CO via thermochemical reactions such as the Boudouard reaction that produce two moles of CO for every mole of CO2, as shown in Formula 1 , where C(s) represents solid Carbon.

[0060] Formula 1 : [0061] Because the Boudouard reaction is a high-temperature reaction, the CO2 captured from the calciner 240 can be directly reacted with the solid carbon without the need for cooling before supplying the CO2 to the carbon monoxide converter 410.

[0062] In some embodiments, the carbon monoxide converter 410 coverts the CO2 to CO via electrolysis, which produces two moles of CO and one mole of O2 for every two moles of CO2, as shown in Formula 2.

[0063] Formula 2:

[0064] Splitting of CO2 via electrolysis has the advantage of producing O2, which may be fed back to the calciner 240 to reduce the demand for O2 from external sources, vented to atmosphere, or stored for other uses.

[0065] Figure 4B is a block diagram for integration of the carbon capture process with electricity and hydrogen generation via electrolysis, according to embodiments of the present disclosure. To produce various products from CO or CO2 captured during the cement or lime manufacturing process, such as liquid fuels, chemical reagents, and plastics, H2 is first produced as a component for the various hydrocarbon products. Accordingly, the system may include a hydrogen generator 430 for producing H2 via electrolysis, the water-gas shift reaction, or thermochemical water splitting. The production of H2 may be performed as one element of a carbon reprocessing system to produce the H2 inputs for converting CO or CO2 into various hydrocarbon compounds such as liquid fuels, various chemicals, or plastics for later use or eventual sequestration. Accordingly, the hydrogen generator 430 is one example of a carbon reprocessing system.

[0066] In some embodiments, the hydrogen generator 430 coverts two moles of water (H2O) one mole of O2 and two moles of H2, according to Formula 3.

[0067] Formula 3:

[0068] Similarly to the electrolysis of CO2 to CO, the O2 may be fed back into the calciner 240, vented, or stored for other uses, and the H2 is captured for further processing. In various embodiments, a first kiln 110 may be associated with the carbon capture system shown in Figure 4A to produce CO for further processing with the H2 produced by the carbon capture system shown in Figure 4B that is associated with a second kiln 110. When the two kilns 110 are paired with one another, the outputs of the respective carbon reprocessing systems (e.g., CO, H2, and O2) may be used as reagents for producing various other hydrocarbon materials or products. Additionally or alternatively, one kiln 110 may provide a first portion of the flue gas output to the carbon capture system shown in Figure 4A and a remainder of the flue gas output to the carbon capture system shown in Figure 4B to provide the different reagents. Similarly, the outputs from one calciner 240, which may serve one or more kilns 110, may provide output CO2 to both a carbon monoxide converter 410 and a hydrogen generator 430, either simultaneously or at different times.

[0069] In various embodiments, some or all of the electricity used to run the electrolysis processes (e.g., for CO, O2, or H2 generation) or other aspects of the carbon capture process (e.g., to rotate the kiln 110, control when a purger 230 forwards or purges material, etc.) is generated by an electrical generator 420 powered via the hydrator 250 using a steam turbine cycle (e.g., the Rankine cycle). The hydrator 250 transfers heat to a working fluid via a heat exchanger 422 included in the hydrator 250, which rotates a turbine 424 to produce electricity. The working fluid is passed to a condenser 426 to remove excess heat before being returned to the heat exchanger 421 to collect more heat from the hydrator 250 via a pump 428. In various embodiments, the working fluid may be water/steam, supercritical carbon dioxide (e.g., via the Allam-Festveldt cycle), a Water/Ammonia mixture (e.g., via the Kalina cycle), or organic fluids (e.g., via the Organic Rankine cycle). Electrolysis occurs at near ambient temperatures, so thermal energy can also be extracted from the CO2 stream in addition to from the hydrator 250.

[0070] In various embodiments, the electricity generated from the electrical generator 420 may be supplemented by a power grid, the carbon capture system associated with a different kiln 110, renewable generators, or other external sources. Similarly, excess electricity generated from the electrical generator 420 beyond that needed to perform electrolysis, may be provided to a carbon capture system associated with a different kiln 110, stored for later use, or output to a power grid.

[0071] Figure 5 is a flowchart of an example method 500 for gas capture from industrial point-sources, according to embodiments of the present disclosure. Method 500 may describe a cyclical process, where some or all of the recited operations are performed in parallel while a kiln 110 or other industrial point-source of CO2 is active, in preparation for activating the kiln 110 or other industrial pointsource, or during shutdown operations of the kiln 110 or other industrial pointsource.

[0072] At block 505, a first chemical reactor (e.g., a carbonator 210) contacts flue gas from a kiln 110 with a calcium-based solid sorbent to produce a calcium- based precipitate and a lean gas with a lower concentration of CO2 than the flue gas. In various embodiments, the calcium-based solid sorbent is Ca(HO)2, which may include fresh material or reprocessed material from an early cycle of method 500. The calcium-based precipitate include CaCOs and at least one of CaSO4, CaSOs, and CaCl2, depending on the contents of the flue gas (which may include CO2, SO2, and HCI) and the heat of reaction in the first chemical reactor. The precipitation of CaCOs reduces the concentration of CO2 in the output gas relative to the input gas to produce a lean gas.

[0073] At block 510, a separator 220 separates the lean gas from the calcium- based precipitate. In various embodiments, the separator operates at a first exit temperature of the first chemical reactor when separating the lean gas and the precipitates. The separator may vent the lean gas to atmosphere (per block 515) directly, or via a heat exchanger to reduce the temperature of the lean gas, while allowing the precipitate to remain hot.

[0074] At block 520, a purger 230 (which may be part of the separator 220 in block 510) purges any precipitate unwanted for further use in carbon capture per method 500. In various embodiments, the purged precipitate includes CaCOs and any impurities (e.g., SO4, CaSOs, or CaCI) that were also precipitated from the flue gas, which may be fed back to the kiln 110 as raw materials (e.g., for producing cement or lime), or provided to a calciner 240 to remove carbon from these compounds. In various embodiments, the purged precipitate is fed back into the kiln 110 while still hot. Similarly, the portion of the precipitate that is wanted for use in later operations of method 500 (i.e., not purged) may be fed to a second chemical reactor while still hot.

[0075] At block 525, a second chemical reactor (e.g., a calciner 240) produces CO2 and CaO from CaCOs. In various embodiments, to produce CO2 and CaO from the CaCOs, the second chemical reactor heats one or more of the calcium- based precipitates that were not purged per block 520 and fresh CaCOs. In various embodiments, the second chemical reactor receives fuel and O2 to provide the heat to convert the CaCOs into CO2 and CaO, but may also be heated via solar collection or electrical heating elements.

[0076] At block 530, a separator 220 separates the CO2 from the CaO produced by the second chemical reactor to provide the CO2 to a carbon reprocessing system. The carbon reprocessing system may include various chemical reactors to produce other carbon-based products from the CO2, which may include hydrocarbon fuels, industrial chemical reagents, plastics, polymers, monomers, or the like for later use or sequestration of the CO2. In various embodiments, the separator 220 operates at the exit temperature of the second chemical reactor, which allows the heated CO2 and CaO to be provided to downstream processes (e.g., the kiln 110, carbon reprocessing system, or hydrator 250) at a high temperature, thereby reducing the energy demands to reheat the CO2 or CaO for those processes.

[0077] At block 535, a purger 230 (which may be part of the separator 220 in block 530) purges any CaO unwanted for further use in carbon capture per method 500. In various embodiments, the CaO may include any unreacted CaCOs or impurities (e.g., SO4, CaSOs, or CaCI) that were also precipitated from the flue gas, which may be fed back to the kiln 110 as raw materials (e.g., for producing cement or lime) when purged. In various embodiments, the purged CaO is fed back into the kiln 110 while still hot. Similarly, the portion of the CaO that is wanted for use in later operations of method 500 (i.e., not purged) may be fed to a third chemical reactor while still hot.

[0078] At block 540, a third chemical reactor (e.g., a hydrator 250) produces Ca(HO)2 by reacting the (unpurged) CaO with steam. In various embodiments, the third chemical reactor operates at or below 512 °C, but may operate at higher temperatures when operated at pressures greater than one atm. In various embodiments, the third chemical reactor receives steam at substantially the operating temperature, but may also include heaters to produce steam of the desired temperature. In some embodiments, the third chemical reactor includes a heat exchanger 252 to use the internal heat within the third chemical reactor to convert liquid water to steam (which may be supplemented by electrically powered or fueled heaters).

[0079] At block 545, a purger 230 (which may be part of the third chemical reactor in block 540) purges any Ca(HO)2 unwanted for further use in carbon capture per method 500. In various embodiments, the Ca(HO)2 may include any unreacted CaO, CaCOs or impurities (e.g., SO4, CaSOs, or CaCI) that were also precipitated from the flue gas, which may be used for other purposes (e.g., fertilizer) when purged. In various embodiments, the purged Ca(HO)2 is used to preheat raw material fed into the kiln 110, convert a working fluid from liquid to gas (e.g., to drive a turbine), or otherwise extract heat for other purposes.

[0080] At block 550, the third chemical reactor supplies the (unpurged) Ca(HO)2 for use as a sorbent in the first chemical reactor to capture additional carbon from the flue gases expelled from the kiln 110.

[0081] Figures 6A-6D are flowcharts of example synergistic methods 600a-d for use with methods for carbon reprocessing and carbon capture from industrial point-sources, according to embodiments of the present disclosure. In various embodiments, one or more of the methods 600a-d may be performed in addition to the method 500 discussed in relation to Figure 5 to extract additional work from waste heat, provide raw materials or fuels for performing operations described in method 500 or provide additional benefit from performing method 500.

[0082] Figure 6A is a flowchart of a first synergistic method 600a to generate electricity from operations performed during method 500, according to embodiments of the present disclosure. In various embodiments, heat from one or more of the chemical reactors in method 500 may be used to drive a turbine 424 to produce electricity to operate (or supplement the operation of) various other systems for carbon capture, carbon reprocessing, operating the point-source, or for external systems. Accordingly, method 600a begins at block 605, where a heat exchanger 422 extracts heat from a chemical reactor (e.g., the hydrator 250) to affect a phase change in a working fluid.

[0083] At block 610, the working fluid turns a turbine to generate electricity and is cycled back to the heat exchanger 422 (e.g., according to a Rankine or Kalina cycle) to extract additional heat from the chemical reactor. In various embodiments, the electricity is used to power electrolysis systems for the generation of O2, H2, or CO for use in other systems (e.g., in a calciner 240, a carbon reprocessing system, etc.) or may be supplied to a power grid or a storage solution (e.g., a battery).

[0084] Figure 6B is a flowchart of a second synergistic method 600b to provide O2 to the chemical reactors discussed in relation to method 500, according to embodiments of the present disclosure. In various embodiments, the electricity used to generate the O2 discussed in the second synergistic method 600b is produced according to the first synergistic method 600a, but may be supplemented in whole or in part with power received from an external source (e.g., a generator, a battery, a flywheel, a solar panel, a wind turbine, or a power grid).

[0085] At block 615, a carbon monoxide converter 410 receives the CO2 separated from the CaO produced by a calciner 240 from CaCOs.

[0086] At block 620, the carbon monoxide converter 410 converts the CO2 into CO and O2. In various embodiments, the carbon monoxide converter 410 is an electrolyzer that electrolyzes the CO2 into O2 and CO via electricity generated from the heat in one or more chemical reactors from method 500. In some embodiments, the carbon monoxide converter 410 is a chemical reactor that uses plasma reactions, thermochemical reactions, or catalytically, to convert the CO2 into O2 and CO (e.g., via the Boudouard reaction).

[0087] At block 625, the carbon monoxide converter 410 feeds the O2 produced during the conversion of CO2 to CO to a chemical reactor. In various embodiments, the chemical reactor is the second chemical reactor (e.g., the calciner 240) used to produce the CO2 being fed to the carbon monoxide converter 410 from the CaCOs. In some embodiments, the O2 is provided as additional oxidizer for the kiln 110, the carbonator 210 (e.g., to enrich the O2 content of the flue gas), or to a carbon reprocessing system for use as a raw material in synthesizing a more desirable product for the captured carbon compounds.

[0088] At block 630, the carbon monoxide converter 410 feeds the CO produced during the conversion of CO2 to CO to a carbon reprocessing system for sequestration or use in manufacturing a different product (e.g., fuel, plastics, organic chemical reagents, etc.).

[0089] Figure 6C is a flowchart of a third synergistic method 600c to increase heat in a chemical reactor via kiln output to reduce heating requirements in the chemical reactor in conjunction with method 500, according to embodiments of the present disclosure. Because the sintering reaction produced by the kiln 110 yields various outputs, such as clinker during the production of cement, that are produced at high heats, and that retain those heats after exiting the kiln 110, the outputs may be used to also transfer heat from the kiln 110 to various portions of the carbon capture system.

[0090] At block 635, the kiln 110 produces clinker as an output. Depending on the temperature of operation of the kiln 110, the clinker may be produced at temperatures between approximately 1300 °C and 1600 °C.

[0091] At block 640, the clinker is fed (e.g., via a conveyor or chute connected to the clinker exit 170 of the kiln 110) to one or more chemical reactors in the carbon capture system. For example, the hot clinker may be supplied to heat the water used by the hydrator 250 from liquid to steam, to heat a working fluid used to power an electrical generator 520, or to transfer the residual heat from the sintering reaction to various other components in the carbon capture system.

[0092] Figure 6D is a flowchart of a fourth synergistic method 600d to generate H2 and O2 for use in or in conjunction with the operations performed during method 500, according to embodiments of the present disclosure.

[0093] At block 645, a hydrogen generator 430 converts H2O into H2 and O2. In various embodiments, the hydrogen generator is an electrolyzer that electrolyzes the H2O into O2 and H2 via electricity generated from the heat in one or more chemical reactors from method 500. In some embodiments, the hydrogen generator 430 is a chemical reactor that uses the water-gas shift reaction, thermal splitting, the steam-process process, or the reforming/gasification of hydrocarbons to convert the CO2 into O2 and CO.

[0094] At block 650, the hydrogen generator 430 feeds the O2 produced during the conversion of H2O to a chemical reactor. In various embodiments, the chemical reactor is the second chemical reactor (e.g., the calciner 240) used to produce the CO2 and CaO from the CaCOs. In some embodiments, the O2 is provided as additional oxidizer for the kiln 110, the carbonator 210 (e.g., to enrich the O2 content of the flue gas), or to a carbon reprocessing system for use as a raw material in synthesizing a more desirable product for the captured carbon compounds.

[0095] At block 655, the hydrogen generator 430 feeds the H2 produced a carbon reprocessing system for sequestration or use in manufacturing a different product (e.g., fuel, plastics, organic chemical reagents, etc.).

[0096] The descriptions and illustrations of one or more embodiments provided in this document are intended to provide a thorough and complete disclosure the full scope of the subject matter to those of ordinary skill in the relevant art and are not intended to limit or restrict the scope of the subject matter as claimed in any way. The embodiments, examples, and details provided in this disclosure are considered sufficient to convey possession and enable those of ordinary skill in the relevant art to practice the best mode of the claimed subject matter. Descriptions of structures, resources, operations, and acts considered well-known to those of ordinary skill in the relevant art may be brief or omitted to avoid obscuring lesser known or unique aspects of the subject matter of this disclosure. The claimed subject matter should not be construed as being limited to any embodiment, aspect, example, or detail provided in this disclosure unless expressly stated herein. Regardless of whether shown or described collectively or separately, the various features (both structural and methodological) are intended to be selectively included or omitted to produce an embodiment with a particular set of features. Further, any or all of the functions and acts shown or described may be performed in any order or concurrently.

[0097] Additionally, although various chemical compounds are described in the present disclosure, one of ordinary skill in the relevant art will appreciate that various inclusions and impurities in the recited compounds are to be expected. These inclusions and impurities may be non-reactive or reactive during the described processes to produce additional impurities, and are generally omitted from the described reactions. For example, a described combustion reaction may take place using air, which includes Nitrogen and other trace gasses in addition to the Oxygen indicated in a combustion reaction, and the presence of these other gasses are omitted to focus on the reaction of interest for the combustion process. One of ordinary skill in the art will understand that the present disclosure describes the central reaction and not the reactions of the inclusions and impurities. Accordingly a substance described as being “substantially pure” includes a compounds having a purity greater than 90% by volume, weight, or molar ratio as measured by means that are at this time known and generally accepted in the art, where the remaining less than 10% may include reaction or processing impurities. [0098] Having been provided with the description and illustration of the present disclosure, one of ordinary skill in the relevant art may envision variations, modifications, and alternate embodiments falling within the spirit of the broader aspects of the general inventive concept provided in this disclosure that do not depart from the broader scope of the present disclosure.

[0099] As used in the present disclosure, a phrase referring to “at least one of” a list of items refers to any set of those items, including sets with a single member, and every potential combination thereof. For example, when referencing “at least one of A, B, or C” or “at least one of A, B, or C”, the phrase is intended to cover the sets of: A, B, C, A-B, B-C, and A-B-C, where the sets may include one or multiple instances of a given member (e.g., A-A, A-A-A, A-A-B, A-A-B-B-C-C-C, etc.) and any ordering thereof.

[0100] As used in the present disclosure, the term “determining” encompasses a variety of actions that may include calculating, computing, processing, deriving, investigating, looking up (e.g., via a table, database, or other data structure), ascertaining, receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), retrieving, resolving, selecting, choosing, establishing, and the like.

[0101] As used in the present disclosure, the terms “approximately” and “about” encompasses values within ± 5% of a stated quantity, percentage, or range unless a different approximation is explicitly recited in relation to the stated quantity, percentage, or range or the context of the value indicates that a different approximation would be more appropriate. For example, a value identified as about X% may be understood to include values between 0.95*X% and 1.05*X% or between X-0.05X and X+0.05X percent, but may stop at zero or one hundred percent if contextually appropriate. Additionally, all numbers given in the examples (whether indicated as approximate or otherwise) inherently include values within the range of precision and rounding error for that number. For example, the number 4.5 shall be understood to include values from 4.45 to 4.54, while the number 4.50 shall be understood to include values from 4.495 to 4.504.

[0102] The following claims are not intended to be limited to the embodiments shown herein, but are to be accorded the full scope consistent with the language of the claims. Within the claims, reference to an element in the singular is not intended to mean “one and only one” unless specifically stated as such, but rather as “one or more” or “at least one”. Unless specifically stated otherwise, the term “some” refers to one or more. No claim element is to be construed under the provision of 35 U.S.C. § 112(f) unless the element is expressly recited using the phrase “means for” or “step for”. All structural and functional equivalents to the elements of the various embodiments described in the present disclosure that are known or come later to be known to those of ordinary skill in the relevant art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed in the present disclosure is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.