EP4731328A1 - Carbon capture systems and methods including heat transfer - Google Patents

Abstract

Carbon capture systems and methods with integrated heat transfer to a solvent regenerator within the system are provided. The systems and methods use one or more heat pump systems to directly or indirectly transfer the heat of absorption released from the absorption of CO₂ into a solvent to a regenerator of a solvent carbon capture system or process. Other heating sources within the carbon capture system may also be integrated to transfer heat to the regenerator.

Description

CARBON CAPTURE SYSTEMS AND METHODS INCLUDING HEAT TRANSFER

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present disclosure claims priority from US Provisional Application No. 63/515248, filed July 24, 2023, entitled “CARBON CAPTURE SYSTEMS AND METHODS INCLUDING HEAT TRANSFER”, which is herein incorporated by reference in its entirety.

BACKGROUND

[0002] Carbon dioxide (CO2) emissions are a significant contributor to greenhouse gases. For example, byproducts of fossil fuel combustion include CO2 and other greenhouse gas emissions. During the combustion of fossil fuels, such as in electric power plants for the generation of electricity, flue gas from a furnace, boiler, or engine is emitted through one or more stacks to the atmosphere. The flue gas includes one or more pollutants, such as carbon dioxide, and other pollutants, including sulfur oxides, nitrogen oxides, and particulate matter. The CO2 is conventionally removed from such materials to reduce greenhouse gas emissions. In addition, carbon dioxide may also be present in natural gas or biogas generated from anaerobic digesters. The CO2 may be removed from the natural gas or biogas to the increase the concentration of methane in such materials for subsequent use.

[0003] Many approaches have been developed to recover CO2 and other acid gases from post combustion gases and industrial gases. For example, some methods of capturing CO2 from a flue gas include the use of an absorber in which the flue gas is absorbed by a liquid absorbent that interacts with the CO2 in the flue gas to separate the CO2 from the flue gas and form a CO2 lean gas having a lower concentration of CO2 than the flue gas. The absorbent becomes loaded (or enriched; referred to as a “loaded absorbent”) with the CO2 and the other acid gases that may be present in the flue gas. The CO2 and other acid gases are subsequently removed from the loaded absorbent to form a CO2 rich gas. Removal of the CO2 and other acid gases from the loaded absorbent regenerates the absorbent and forms a lean absorbent having a lower concentration of absorbed CO2 than the loaded absorbent. The lean absorbent is circulated back to the absorber and the process of absorbing the CO2 and other acid gases from the flue gas with the absorbent is continued. The C02-rich gas may be compressed and utilized in an industrial process and/or injected into a subterranean formation (e.g., depleted hydrocarbon reservoirs in the subterranean formation) for storage.

[0004] The present disclosure generally relates to carbon capture, and more particularly to systems and methods using a heat pump to transfer the heat of absorption released from the absorption of CO2 into a solvent to a stripping section of a solvent carbon capture system or process.

SUMMARY

[0005] In some configurations, a carbon capture method includes collecting waste heat produced by a solvent absorption process and transferring the collected waste heat to a solvent regeneration process.

[0006] Collecting waste heat can include collecting waste heat comprises extracting the waste heat from cooling water of interstage coolers in an absorber section of a carbon capture system.

[0007] In some configurations, a carbon capture system includes an absorber section, a regenerator section, and a heat pump.

[0008] The heat pump can be configured to recover waste heat from the absorber section and transfer the waste heat to the regenerator section in use. The absorber section can include interstage coolers. The heat pump can be configured to recover waste heat from cooling water of the interstage coolers.

BRIEF DESCRIPTION OF THE FIGURES

[0009] Certain embodiments, features, aspects, and advantages of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein.

[0010] FIG. 1 schematically illustrates a solvent carbon capture system with heating source integration;

[0011] FIG. 2 schematically illustrates an example heat pump refrigeration system; [0012] FIG. 3 schematically illustrates the solvent carbon capture system having interstage coolers coupled with the heating source;

[0013] FIG. 4 schematically illustrates the solvent carbon capture system having a direct contact cooler coupled with the heating source;

[0014] FIG. 5 schematically illustrates the solvent carbon capture system having a wash system coupled with the heating source;

[0015] FIG. 6 schematically illustrates the solvent carbon capture system having multiple heat pump systems coupled with the heating source; and

[0016] FIG. 7 illustrates a method of integrating a solvent carbon capture system to transfer waste heat from components or fluids of the system to a regenerator of the system.

DETAILED DESCRIPTION

[0017] In the following description, numerous details are set forth to provide an understanding of some embodiments of the present disclosure. It is to be understood that the following disclosure provides many different embodiments, or examples, for implementing different features of various embodiments. Specific examples of components and arrangements are described below to simplify the disclosure. These are, of course, merely examples and are not intended to be limiting. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments are possible. This description is not to be taken in a limiting sense, but rather made merely for the purpose of describing general principles of the implementations. The scope of the described implementations should be ascertained with reference to the issued claims.

[0018] As used herein, the terms “connect”, “connection”, “connected”, “in connection with”, and “connecting” are used to mean “in direct connection with” or “in connection with via one or more elements”; and the term “set” is used to mean “one element” or “more than one element”. Further, the terms “couple”, “coupling”, “coupled”, “coupled together”, and “coupled with” are used to mean “directly coupled together” or “coupled together via one or more elements”. As used herein, the terms "up" and "down"; "upper" and "lower"; "top" and "bottom"; and other like terms indicating relative positions to a given point or element are utilized to more clearly describe some elements. Commonly, these terms relate to a reference point at the surface from which drilling operations are initiated as being the top point and the total depth being the lowest point, wherein the well (e.g., wellbore, borehole) is vertical, horizontal or slanted relative to the surface.

[0019] In a typical absorption process, the solvent is regenerated using distillation in a regenerator. Due to the vapor / liquid equilibrium, absorption of carbon dioxide or acid gases by the solvent favors low temperature, but regeneration of the solvent requires elevated temperature. The distillation operation is an endothermic process that needs heat input. In some embodiments, the operating temperature range of the regenerator may be between about 100°C to about 150°C, between about 110°C to about 130°C, or above 115°C. The absorption process is an exothermic process that releases heat, thereby heating the solvent. The heated solvent may have a reduced capacity to absorb and/or retain the acid gas (e.g., carbon dioxide). One or more interstage coolers may be used with the absorber to remove the heat from the solvent in the absorber to maintain a desirable operating temperature for the solvent. In some embodiments, the operating temperature range of the absorber may be between about 30°C to about 70°C, such as from about 30°C to about 40°C, from about 40°C to about 50°C, from about 50°C to about 60°C, or from about 60°C to about 70°C. If the solvent is a chemical solvent in which reversible chemical reactions occur during the absorption and regeneration processes, the heat released from the absorber and heat input to the regenerator can be significant.

[0020] Due to the low temperature of the absorber during operation, the heat removed by the interstage coolers is considered waste heat and not reused in the current art. Cooling water or air is commonly used as the cooling media in the one or more interstage coolers. Cooling water or air usage involves capital equipment and operation expenses. Other parts of the process also require cooling. For example, the flue gas prior to routing through the absorber, the lean solvent prior to routing to the absorber, the extracted gas from the regenerator, a wash system working fluid, or other systems may desirably be cooled and thus potential sources of available heat to add to the regenerator. In the meantime, the regenerator utilizes heat input to provide elevated temperature for regeneration of the solvent. This heat input may be achieved through heating media such as steam or hot oil. As discussed herein, some or all of the heat input may be provided to the regenerator from other components of a solvent carbon capture system. In some embodiments, some or all of the heat input provided to the regenerator may be sourced from one or more heat pumps of the solvent carbon capture system. Thus, what may otherwise be termed waste heat from the carbon capture system may be utilized to at least partially contribute to regenerating the solvent of the solvent carbon capture system. An absorption / regeneration process of a solvent carbon capture system is schematically illustrated in Figure 1.

[0021] FIG. 1 is a simplified schematic illustrating a carbon capture system 100, according to at least one embodiment of the disclosure. The carbon capture system 100 is configured to remove CO2 and other acid gases from a carbon dioxide-containing (CCh-containing) gas 102. The CCh-containing gas 102 may be a flue gas from a combustion process or another gas from an industrial process. Prior to treatment in the carbon capture system 100, the CCh-containing gas 102 may be treated by one or more air pollution control devices, such as electrostatic precipitators (ESPs), flue gas desulfurization (FGD) units, selective catalytic NOx reduction (SCR) units, a scrubber, or other emission control devices to reduce the emission of particulates and other materials to the atmosphere. In some embodiments, the CCh-containing gas 102 includes solid particles in aerosol form carried in the CO2- containing gas 102. The solid particles may include, for example, dust, fines, or other particulate matter that may be generated by processes that generate the flue gas and not completely removed by air pollution control devices. The solid particles may have a size (e.g., diameter) less than about 10 micrometers (pm). As described herein, the carbon capture system 100 may include a condenser (e.g., direct contact cooler (DCC) configured to facilitate agglomeration and removal of the particulate matter from a CCh-containing gas 102.

[0022] The CCh-containing gas 102 may be provided to an absorber 104 where the CO2 in the CCh-containing gas 102 may be at least partially (e.g., substantially) removed from the CCh-containing gas 102 to form a carbon dioxide-lean (CCh-lean) gas 106 having a lower concentration of CO2 than the CCh-containing gas 102. A temperature of the CCh- containing gas 102 may be within a range of from about 40°C to about 160°C, such as from about 40°C to about 60°C, from about 60°C to about 90°C, or from about 90°C to about 120°C. The temperature of the CCh-containing gas 102 may be controlled by, for example, passing the CCh-containing gas 102 through a DCC (discussed below) prior to introducing the CCh-containing gas 102 to the absorber 104. In some embodiments, the temperature of the CCh-containing gas 102 after exiting the DCC and prior to entering the absorber 104 is within a range of from about 25°C to about 40°C. In some embodiments, the absorber 104 may be configured to remove from about 85 percent to about 95 percent of the CO2 from the CCh-containing gas 102. In some such embodiments, from about 5 percent to about 15 percent of the CO2 originally present in the CCh-containing gas 102 remains in the CO2- lean gas 106. However, depending on the operating conditions of the absorber 104, the efficiency of CO2 removal from the CCh-containing gas 102 may be as high as or higher than about 99 percent or even higher.

[0023] The CCh-containing gas 102 may be provided to a lower portion of the absorber 104 and flow countercurrent to a solvent (e.g., a lean solvent 108) provided to an upper portion of the absorber 104. The lean solvent 108 may flow downwardly (e g., such as by gravity) through the absorber 104 countercurrent to the CCh-containing gas 102. The lean solvent 108 absorbs CO2 from the CCh-containing gas 102 to remove CO2 from the CCh-containing gas 102 and form the CCh-lean gas 106. Absorption of the CO2 from the CCh-containing gas 102 loads the lean solvent 108 with CO2 and forms a loaded solvent 110 (also referred to as a “CCh-rich absorbent,” a “loaded solvent,” a “CCh-rich solvent,” or “a CCh-loaded solvent”), which exits at a bottom of the absorber 104.

[0024] The lean solvent 108 and the loaded solvent 110 may each include substantially the same material composition, except that the lean solvent 108 may include less CO2 absorbed therein than the loaded solvent 110. In some embodiments, the lean solvent 108 and the loaded solvent 110 include a NAS. Reference to the solvent herein refers to the NAS. The NAS may include an organic solvent system that may be partially miscible with water or immiscible with water. The NAS may include polar aprotic solvent systems, protic solvent systems, and mixtures thereof. In some embodiments, the NAS includes a nitrogenous base (e.g., an amine, such as an organic amine) and an organic diluent. In some embodiments, the NAS further includes water.

[0025] The nitrogenous base of the NAS may include an amine (e.g., a primary amine, a secondary amine), an amidine, a guanidine (e.g., 1,1, 3, 3 -tetramethylguanidine (“TMG”)), a triazole (e.g., 1,2,3-triazole, 1,2,4-triazole), or combinations thereof. In some embodiments, the nitrogenous base includes a hydrophobic amine. The amine may include one or more of N-methylbenzylamine (NMBA), 2-fluoro-N-methylbenzylamine, 3-fluoro-N-methylbenzylamine, 4-fluoro-N-methylbenzylamine, 3,5- difluorobenzylamine, l,4-diazabicyclo-undec-7-ene (“DBU”), l,4-diazabicyclo-2,2,2-octane, piperazine (“PZ”), tri ethylamine (“TEA”), 1,8- diazabicycloundec-7-ene, monoethanolamine (“MBA”), diethyl amine (“DEA”), ethylenediamine (“EDA”), methyl diethanolamine (MDEA), 2-amino 1 -propanol (AMP), 1,3-diamino propane, 1,4-diaminobutane, hexamethylenediamine, 1,7-diaminoheptane, diethanolamine, diisopropylamine (“DIP A”), 4-aminopyridine, pentylamine, hexylamine, heptylamine, octylamine, nonyl amine, decylamine, tert-octylamine, dioctylamine, dihexylamine, 2-ethyl-l -hexylamine, 2-fluorophenethylamine, 3 -fluorophenethylamine,

4-fluorophenethylamine, D-4-fluoro-alpha-methylbenzylamine, L-4-fluoro-alpha- methylbenzylamine, imidazole, benzimidazole, N-methyl imidazole, 1 -trifluoroacetylimidazole, or combinations thereof. In some embodiments, the hydrophobic amine includes N-methylbenzylamine.

[0026] The organic diluent may include a polyether diluent and may be selected from the group consisting of alcohols, ketones, aliphatic hydrocarbons, aromatic hydrocarbons, nitrogen heterocycles, oxygen heterocycles, aliphatic ethers, cyclic ethers, esters, and amides and mixtures thereof. In some embodiments, the organic diluent includes a polyether diluent, such as a polyethylene glycol dialkyl ether. By way of non-limiting example, the organic diluent may include a polyglycol dimethyl ether, a polyglycol dibutyl ether, or a combination thereof. In some embodiments, the organic diluent includes diethylene glycol dibutyl ether, triethylene glycol dibutyl ether, tetraethylene glycol dibutyl ether, or combinations thereof. In some embodiments, the organic diluent includes triethylene glycol dibutyl ether. In some embodiments, the organic diluent includes a polyethylene glycol dialkyl ether, such as Genosorb® 1843, commercially available from Clariant of Muttenz, Switzerland. The organic diluent may be formulated and configured to remove at least some of the acid gases (e g., CO2) in the CCh-containing gas 102 by directly contacting the CCh-containing gas 102.

[0027] In some embodiments, the nitrogenous base includes NMBA and the organic diluent includes one or more polyethylene glycol dialkyl ethers. In some such embodiments, the NAS includes NMBA and one or more polyethylene glycol dialkyl ethers, such as one or more of diethylene glycol dibutyl ether, triethylene glycol dibutyl ether, or tetraethylene glycol dibutyl ether.

[0028] The NAS may include a mixture of the nitrogenous base, the organic diluent, and water. The NAS may include substantially equal proportions by molarity of the nitrogenous base and the organic diluent. In some such embodiments, the nitrogenous base and the organic diluent are present in the NAS in equimolar amounts.

[0029] Water may constitute from about 2.5 weight percent to about 12.5 weight percent of the NAS, such as from about 2.5 weight percent to about 3.0 weight percent, from about 3.0 weight percent to about 4.0 weight percent, from about 4.0 weight percent to about 5.0 weight percent, from about 5.0 weight percent to about 6.0 weight percent, from about 6.0 weight percent to about 7.0 weight percent, from about 7.0 weight percent to about 8.0 weight percent, from about 8.0 weight percent to about 9.0 weight percent, from about 9.0 weight percent to about 10.0 weight percent, from about 10.0 weight percent to about 11.0 weight percent, or from about 11.0 weight percent to about 12.5 weight percent of the NAS. In some embodiments, water constitutes from about 7.0 weight percent to about 8.0 weight percent of the NAS. However, the disclosure is not so limited, and the weight percent of the water in the NAS may be different than that described. In some embodiments, the NAS includes about 55 weight percent of the nitrogenous base, about 37 weight percent of the organic diluent, and about 8 weight percent of water.

[0030] The NAS may have a density within a range of from about 0.90 g/cm³ to about 0.98 g/cm³, such as from about 0.90 g/cm³ to about 0.92 g/cm3, from about 0.92 g/cm³ to about 0.94 g/cm³, from about 0.94 g/cm³ to about 0.96 g/cm³, or from about 0.96 g/cm³ to about 0.98 g/cm³. In some embodiments, the density of the NAS is about 0.94 g/cm³.

[0031] The absorber 104 may be configured to provide sufficient contact between the CCh-containing gas 102 and the lean solvent 108 to facilitate absorption of CO2 and other acid gases present in the CCh-containing gas 102 by the lean solvent 108 to form the CO2- lean gas 106. Contacting the lean solvent 108 with the CCh-containing gas loads the lean solvent 108 with the CO2 to form the loaded solvent 110. The absorber 104 may include one or more sections of packed beds 105 including one or more packing materials. The packing materials may include, for example, stainless steel, structured packing materials, Pall rings, rings of steel or aluminum, other packing materials, or combinations thereof. In some embodiments, the absorber 104 includes trays (e.g., sieve trays, valve trays) through which the lean solvent 108 falls via gravity as the gas passes upwardly through the trays while contacting the lean solvent 108.

[0032] The absorber 104 may further include or be operably coupled to one or more interstage coolers 112 configured to cool the solvent 108 as the solvent 108 flows downwardly through the absorber 104. Cooling the solvent 108 may increase the CO2 capacity of the solvent 108 and facilitate improved capture of CO2 from the CCh-containing gas 102. The interstage coolers 112 may cool the solvent using water or air, for example. The solvent 108 may be provided to the interstage coolers 112 by means of a pump. As discussed in detail below, the interstage cooler 112 may include a heat pump system. While the absorber 104 has been described as including two section of packed beds 105 and one interstage cooler 112, the disclosure is not so limited, and the absorber 104 may include a different (e.g., a greater) number of packed beds 105 and interstage coolers 112. In some embodiments, a wash system is configured to receive and wash the CCh-lean gas 106 to reduce or eliminate entrained solvent 108 or other components.

[0033] With reference to FIG. 1, the loaded solvent 110 may be provided to a regenerator 116 (also referred to as a “regenerator column”) via a pump 115. The regenerator 116 is configured to remove the CO2 and other acid gases from the loaded solvent 110 and form the lean solvent 108 that is provided to (e.g., recycled to, circulated to) the absorber 104. Thus, the regenerator 116 facilitates removal of CO2 and other acid gases from the loaded solvent 110 to form the lean solvent 108. Accordingly, the solvent may be circulated through the carbon capture system 100 to capture CO2 in the absorber 104, followed by release of the absorbed CO2 in the regenerator 116 and recycling of the solvent to the absorber 104 to continue the process of capturing the CO2 from the CCh-containing gas 102.

[0034] The loaded solvent 110 may be provided to an upper section of the regenerator 116 and flow downwardly in the regenerator 116. A heating stream 118 may be provided to a lower portion of the regenerator 116 and flow upwardly through the regenerator 116 to contact the downwardly flowing loaded solvent 110 and remove the CO2 and other acid gases from the loaded solvent 110 to form the lean solvent 108. The heating stream 118 may include water vapor and CO2. In some embodiments, a heating source 119 provides heat to the heating stream 118 via a heat exchanger 120 and/or reboiler. Thus, the stream 118 may flow countercurrent to the loaded solvent 110 in the regenerator 116. A portion of the lean solvent 108 exiting the bottom of the regenerator 116 may be returned to the reboiler or heating source 119. The heating source 119 may re-heat the portion of the lean solvent 108 to generate the stream 118 provided to the regenerator 116. The stream 118 may further include volatilized solvent. In some embodiments, the heating source 119 heats the lean solvent 108 to a temperature within a range of from about 110°C to about 150°C. As discussed herein, the heating source 119 may include multiple heating sources such as a first heater 121 and a second heater 123. The first heater 121 may include a reboiler, boiler, resistance heater, heat pump, or other heater. In some embodiments, the first heater 121 directly utilizes a fuel or energy source (e g., electricity) to provide primary heat to the heating stream 118. The second heater 123 may include a heat transfer system that directly or indirectly receives heat (e.g., absorption heat, waste heat) from another component of the solvent carbon capture system 100, as discussed in detail below. For example, the second heater 123 may be the interstage cooler 112. In some embodiments, heat rejected from other components or fluids of the solvent carbon capture system 100 is directed to the second heater 123. For example, the heat from one or more components of the solvent carbon capture system 100 may be directed to a heat sink. A heat pump system may be utilized to transfer heat from the heat sink to the heating stream 118. Accordingly, the heat sink and heat pump system form the second heater 123 of the heating source 119. A heat load ratio of heating input provided by the heating source 119 to the heating stream 118 may be approximately 20:80 between the first heater 121 and the second heater 123, approximately 25:75 between the first heater 121 and the second heater 123, approximately 40:60 between the first heater 121 and the second heater 123, approximately 50:50 between the first heater 121 and the second heater 123, approximately 60:40 between the first heater 121 and the second heater 123, or approximately 75:25 between the first heater 121 and the second heater 123. In some embodiments, the second heater 123 provides more than 80% of the heat input to the heating stream 118. In some embodiments, the second heater 123 provides between 10% to 50% of the heat input to the heating stream 118.

[0035] As described above with reference to the absorber 104, the regenerator 116 may include one or more sections of packed beds 117 including one or more packing materials such as, for example, stainless steel, structured packing materials, Pall rings, rings of steel or aluminum, other packing materials, or combinations thereof. In some embodiments, the regenerator 116 includes trays (e.g., sieve trays, valve trays) through which the solvent falls via gravity as the stream 118 passes upwardly through the trays while contacting the CO2- rich solvent 110. While FIG. 1 illustrates that the regenerator 116 includes two sections of packed beds 117, the disclosure is not so limited. In other embodiments, the regenerator 116 includes a single section of a packed bed 117 or includes more than two sections of packed beds 117.

[0036] With continued reference to FIG. 1, regenerating the NAS in the regenerator 116 releases the CO2 from the loaded solvent 110 and forms a CCh-rich product 124 that exits the top of the regenerator 116. In some embodiments, vapors entrained in the CCh-rich product 124 are condensed in a cooler 125 and collected in vessel (e.g., a decanter) 127. A reflux 129 including a liquid comprising the condensed vapors may be recycled to the regenerator 116. In some embodiments, the reflux 129 includes water. Vapors from the vessel 127 include a CO2-rich product 124 from which water and other liquids have been removed. The CCh-rich product 124 may be further processed to remove any impurities (e.g., solvent, steam) therefrom. The CO2 product 131 may be stored in an earth formation (e.g., sequestered), may be used in the manufacture of other materials (e.g., ethanol, sustainable aviation fuel, chemicals, mineral aggregates, and/or other materials), or combinations thereof.

[0037] After leaving the bottom of the regenerator 116, the lean solvent 108 may be provided to the absorber 104. In some embodiments, a pump 126 pumps the lean solvent 108 to a heat exchanger 128 configured to heat the loaded solvent 110 from the bottom of the absorber 104 with the lean solvent 108 from the bottom of the regenerator 116 and cool the lean solvent 108 entering the absorber 104. In some embodiments, the lean solvent 108 may be further cooled in a cooler 133 to lower a temperature of the lean solvent 108 and increase a CO2 capacity of the lean solvent 108 in the absorber 104. In some embodiments, the cooler 133 is substantially the same as the interstage cooler 112.

[0038] The present disclosure provides systems and methods to couple heat released from cooling needs of a system or method of a solvent carbon capture system (e.g., interstage coolers, direct contact coolers, lean-solvent coolers, condensation coolers, wash systems) with heat input to be provided to the regenerator of the solvent carbon capture system. That is, heat removed from components and flows of the solvent carbon capture system may be integrated with other components and flows of the solvent carbon capture system that are heated. Such systems and methods advantageously can provide significant savings in energy demand in the absorption / regeneration process.

[0039] The 2^nd law of thermodynamic indicates that heat cannot be transferred from a low temperature body to a high temperature body without the aid of an external agency (the Kelvin statement of the 2^nd law of thermodynamic). A heat pump is such an external agency that enables heat transfer from low temperature to high temperature by consuming a small amount electricity. Frequently, the energy utilized by the heat pump itself may be added to the high temperature body. An example of a heat pump is a system running on refrigeration cycle. The heat pump refrigeration cycle 200 is schematically shown in Figure 2.

[0040] In the heat pump system 200, a compressor or pump 202 provides a working fluid 204 (e.g., refrigerant, water, water-glycol mixture) to a condenser 206. Typically, the working fluid 204 provided to the condenser 206 is a gas or contains a gaseous fluid. The working fluid 204 rejects heat to a heating fluid 208, such as the heating stream 118 discussed above or an intermediate fluid. The rejection of the heat from the working fluid 204 to the heating fluid 208 thereby cools and condenses the working fluid. The working fluid 204 may then be expanded in an expansion valve 210, thereby changing the working fluid 204 at least partially to a gas. The expanded working fluid 204 may then be heated in an evaporator 212. A secondary fluid 214 directed through the evaporator 212 is configured to rej ect or transfer heat to the working fluid 204, thereby cooling the secondary fluid 214. For example, the secondary fluid 214 may be the solvent 108 in the absorber 104, the lean solvent 108 in the cooler 133 prior to the absorber, the wash water, or the CCh-rich gas directed through the DCC. In some embodiments, the secondary fluid 214 is a heat exchange medium. Accordingly, energy applied to the pump 202 of the heat pump system 200 may be configured to transfer heat from the secondary fluid 214 to the working fluid 208.

[0041] The fluids (e.g., working fluid 204, heating fluid 208, secondary fluid 214) utilized in the heat pump system 200 may include, but are not limited too one or more of ammonia (NH3), propane, ethylene glycol, difluoromethane (CH2F2), pentafluoroethane (CHF2CF3), chlorodifluoromethane (CHC1F2), 1 , 1 , 1 -trifluoroethane (C2H3F3), 1,1, 1,2- tetrafluoroethane (C2H2F4), 1,1,2,2-tetrafluoroethane (C2H2F4), chilled water, another refrigerant, or combinations thereof. However, the disclosure is not limited to the particular refrigerants of the heat transfer medium, and the heat transfer medium may include other refrigerants.

[0042] The evaporator 206 and condenser 212 may include any type of heat exchanger configured to facilitate the transfer of thermal energy between the working fluid 204 and another fluid (e.g., heating fluid 208, secondary fluid 214, CO2-rich gas 102, CO2-lean gas 106, solvent 108). By way of non-limiting example, the evaporator 206 and condenser 212 may include a surface condenser, an evaporator, a plate and frame heat exchanger, or another type of heat exchanger. However, the disclosure is not limited to the particular type of condenser.

[0043] In systems and methods of the present disclosure, one or more heat pumps are used to recover the waste heat of absorption and transfer it into a high temperature heating medium, such as the secondary heater 123 of the heating source 119. The heating medium may be the heating stream 118 provided by the heating source 119. Waste heat can also be recovered from other parts of the process where there are cooling needs. The high temperature heating medium can be used to provide the heat for the solvent regeneration in the regenerator 116. FIGS. 3-6 illustrate embodiments of the solvent carbon capture system in which heat pump systems 200 transfer heat from a secondary fluid 214 to a heating fluid 208, which in turn is provided to the heating stream 118 to transfer heat to the regenerator 116. For clarity in the drawings, the same reference numbers from FIGS. 1 and 2 are applied to similar components of the solvent carbon capture system 100 in FIGS. 3-6.

[0044] FIG. 3 illustrates an embodiment of the solvent carbon capture system with multiple interstage coolers 112 of the absorber 104. While two interstage coolers 112 are illustrated, it is appreciated that the absorber 104 may include three, four, five, or more interstage coolers 112. One or more of the interstage coolers 112 may be configured to transfer absorption heat from the solvent 108 to a heating fluid via a heat pump system 200. In some embodiments, one or more heat pump systems 200 transfer heat to a heat sink 300. The heat sink 300 may be the secondary heater 123 or may itself be configured to transfer heat to the secondary heater 123 of the heating source 119 for heat transfer to the heating stream 118 and the regenerator 116. In some embodiments, the heat sink 300 is a thermal storage system that may also receive some heat from sources other than the solvent carbon capture system. For example, additional sources for heat to the heat sink 300 may include an electrical plant, a petrochemical plant, a cement plant, thermal reservoir, or industrial facility.

[0045] FIG. 4 illustrates an embodiment of the solvent carbon capture system with a direct contact cooler (DCC) 400 configured to cool the CCh-rich gas 102 prior to entering the absorber 104. The heat removed from the DCC 400 may otherwise be considered waste heat that is rejected to the atmosphere or reservoir. Cooling of the CCh-rich gas 102 may facilitate greater absorption of CO2 by the solvent 108. As discussed above, the DCC 400 may be configured to reduce the temperature of the CCh-rich gas 102 entering the absorber from temperatures greater than 120°C, greater than 150°C, or greater than 160°C to temperatures less than 40°C, less than 30°C, or less than 20°C. The DCC 400 may be configured to transfer heat from the CCh-rich gas 102 to a heating fluid via a heat pump system 200. In some embodiments, the heat pump system 200 coupled to the DCC 400 may be secondary heater 123 or may itself be configured to transfer heat to the secondary heater 123 of the heating source 119 for heat transfer to the heating stream 118 and the regenerator 116.

[0046] FIG. 5 illustrates an embodiment of the solvent carbon capture system with a solvent wash system 500 configured to process the CCh-lean gas 106 to wash out particular components (e.g., vaporized solvent, emissions, particulates) to form a washed gas 506. The washed gas 506 may be directed to a stack or to another system for further processing. In some embodiments, the wash fluid is a water, an acid mixture, or a solvent mixture. A wash fluid treatment system 502 may treat wash fluid received from the solvent wash system 500 for disposal, return to the solvent wash system 500, or to the solvent 108. In some embodiments, the wash fluid treatment system 502 may condense vaporized solvent 108 for return to the absorber 108. In some embodiments, the wash fluid treatment system 502 may neutralize one or more components of the wash fluid for subsequent use or disposal. [0047] The wash fluid may also absorb heat from the CCh-lean gas 106. The wash fluid treatment system 502 may be configured to transfer heat from the wash fluid to a heating fluid via a heat pump system 200. In some embodiments, the heat pump system 200 coupled to the solvent wash system 500 may be secondary heater 123 or may itself be configured to transfer heat to the secondary heater 123 of the heating source 119 for heat transfer to the heating stream 118 and the regenerator 116.

[0048] FIG. 6 illustrates an embodiment of the solvent carbon capture system 600 with multiple heat pump systems 200 configured to transfer heat to heat sink 300. While the solvent carbon capture system 600 illustrates multiple heat pump systems 200 and each is coupled to the heat sink 300, some embodiments, may include more or fewer heat pump systems 200.

[0049] The heat pump system 200-1 may transfer heat from the DCC 400 to the heat sink 300. As discussed above, the DCC 400 may absorb heat from the CCh-rich gas 102 prior to entering the absorber 104. This heat rejected from the CCh-rich gas 102 may be called pre-treatment heat. In some embodiments, the CCh-rich gas 102 may be cooled from approximately 120°C to approximately 40°C or less. The heat pump system 200-2 may transfer absorption heat from the solvent 108 (via the interstage coolers 112) to the heat sink 300. In some embodiments, the solvent 108 may be cooled in the interstage coolers 112 from approximately 80°C to approximately 40°C. The heat pump system 200-3 may absorb heat from the CCh-lean solvent 108 prior to entering the absorber 104, and transfer such heat to the heat sink 300. In some embodiments, the heat pump system 200-3 is configured to cool the solvent to less than approximately 40°C, less than approximately 30°C, or less than approximately 20°C. This heat rejected from the CCh-lean solvent 108 may be called pre-absorption heat. The heat pump system 200-4 may absorb heat from the CCh-rich product 124 prior to storage, transport, or utilization of the CCh-rich product 124. This heat rejected from the CCh-rich product 124 may be called product heat.

[0050] In some embodiments, the heat sink 300 includes a thermal reservoir, such as an insulated mass or fluid. In some embodiments, the heat sink 300 is the secondary heater 123 of the heating source 119, and another heat pump system of the secondary heater 123 is configured to transfer heat from the heat sink 300 to one or both of the working fluid 208 and the heating stream 118. As discussed above, a first heater 121 may be configured to provide primary heat to one or both of the working fluid 208 and the heating stream 118 to heat the CCh-rich solvent 110 in the regenerator 116.

[0051] In carbon capture applications, the heat pump systems can extract the heat from the cooling fluid (e.g., air, water, water mixture, oil) of the interstage coolers (as low as 15°C) in the absorber 104, and then use the heat to generate steam for a reboiler (e.g., heating source 119) configured to heat the regenerator 116. In some embodiments, the heating source 119 is configured to provide steam, a working fluid 208, and/or a heating stream 118 with a temperature up to approximately 130°C, 140°C, or 150°C. Heat from a variety of sources may be transferred to the heating source 119 to be utilized for heating the regenerator 116 and regenerating the solvent 108. In some embodiments, the quantity or quality of the heat transferred from an individual component within the solvent carbon capture system may be low. However, the cumulative effect of heat transfer from multiple sources in addition to the efficiency gains of the heat pump systems coupled to the second heater 123 may facilitate the reduction of additional energy provided to the heating stream by primary heat from the first heater 121 of the heating source 119. Such heat pump systems and methods may advantageously minimize heat lost in the overall process. Such heat pump systems and methods integrated within a solvent carbon capture system may also advantageously reduce the total amount of utility water required for the process, for cooling on the absorption side and for heating on the stripping side, which is especially beneficial for facilities that do not have an abundant supply of water.

[0052] An example configuration is as follows. In use, heat may be sourced from the hot solvent extracted from the interstage coolers of the absorption tower, with the temperatures of the solvent as low as 15°C. This hot solvent is pumped over the heat exchanger surface of the heat pump. The heat from the hot solvent is warm enough to cause the refrigerant in the heat pump to evaporate and turn into vapor. The vapor then moves through a compressor that increases the pressure of the vapor and causes its temperature to rise. The now heated vapor passes over the reboiler heat exchange surface of the heating source 119, and transfers the heat (up to 120°C) to the solvent 110 to be regenerated in the regenerator 116 of the system. As the heat is transferred into heating source 119, the vapor of the refrigerant or working fluid of the heat pump system to fall in temperature and return to a liquid state. This colder liquid state of the refrigerant or working fluid is then transferred back to the heat pump where it can extract the heat from the hot solvent in an interstage cooler and the cycle may be repeated.

[0053] FIG. 7 illustrates a method 700 of integrating a solvent carbon capture system to transfer collected heat (e.g., waste heat) from components or fluids of the system to a regenerator of the system. A solvent is directed to an absorber to absorb carbon dioxide from a gas at 702. Heat is collected from within the solvent carbon capture system at 704. As discussed above, the collected heat may be from one or more interstage coolers, a direct contact cooler, a wash system, a pre-ab sorption heat, a product heat, or any combination thereof. Primary heat is generated by a first heater of a heating source at 706. The primary heat may be from combustion of a fuel, electrical heat, or heat transferred from another system. The collected heat is transferred to a second heater of the heating source at 708. The second heater may include a heat sink, as discussed above. The primary heat and the collected heat are added to at heating stream at 710. The heating stream is provided to a regenerator with the rich solvent at 712. Within the regenerator, the heating stream heats the rich solvent to desorb carbon dioxide from the solvent.

[0054] Language of degree used herein, such as the terms “approximately,” “about,” “generally,” and “substantially” as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” “generally,” and “substantially” may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and/or within less than 0.01% of the stated amount. As another example, in certain embodiments, the terms “generally parallel” and “substantially parallel” or “generally perpendicular” and “substantially perpendicular” refer to a value, amount, or characteristic that departs from exactly parallel or perpendicular, respectively, by less than or equal to 15 degrees, 10 degrees, 5 degrees, 3 degrees, 1 degree, or 0.1 degree.

[0055] Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments described may be made and still fall within the scope of the disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosure. Thus, it is intended that the scope of the disclosure herein should not be limited by the particular embodiments described above.

Claims

CLAIMS What is claimed is:

1. A system for removing carbon dioxide from a carbon dioxide-containing gas, the system comprising: an absorber configured to absorb carbon dioxide from the carbon dioxide- containing gas with a solvent to form a carbon dioxide-lean gas and a rich solvent, wherein the absorption of carbon dioxide generates absorption heat; a heating source configured to provide a heating stream based at least in part on collected absorption heat from the system; and a regenerator coupled to the absorber and the heating source, wherein the heating stream is configured to facilitate desorption of carbon dioxide from the rich solvent.

2. The system of claim 1, wherein the heating source comprises a heat pump system comprising a working fluid, wherein the working fluid is configured to transfer the absorption heat to the heating stream.

3. The system of claim 2, wherein the working fluid comprises water.

4. The system of claim 1, wherein the heating source comprises a first heater configured to generate primary heat, and the heating source comprises a second heater configured to transfer the collected absorption heat to the heating stream, wherein the heating source is configured to provide the heating stream based at least in part on the collected absorption heat and the primary heat.

5. The system of claim 4, wherein a heat load ratio between the first heater and the second heater is between 25:75 to 75:25.

6. The system of claim 1, wherein the heating source comprises one or more interstage coolers of the absorber, wherein the one or more interstage coolers are configured to collect the absorption heat.

7. The system of claim 6, wherein the heating source comprises a direct contact cooler configured to collect pre-treatment heat from the carbon dioxide-containing gas, and the heating source is configured to provide the heating stream based at least in part on collected absorption heat and the pre-treatment heat.

8. The system of claim 6, wherein the heating source comprises a heat pump system configured to collect pre-absorption heat from the solvent flowing into the absorber, and the heating source is configured to provide the heating stream based at least in part on collected absorption heat and the pre-absorption heat.

9. The system of claim 6, wherein the heating source comprises a heat pump system configured to collect product heat from a carbon dioxide product of the regenerator, and the heating source is configured to provide the heating stream based at least in part on collected absorption heat and the product heat.

10. The system of claim 6, wherein the heating source comprises a heat pump system configured to collect wash treatment heat from a wash fluid configured to wash the carbon dioxide-lean gas, and the heating source is configured to provide the heating stream based at least in part on collected absorption heat and the wash treatment heat.

11. The system of claim 6, wherein the heating source comprises a heat sink configured to receive the absorption heat and waste heat from the system.

12. A method of removing carbon dioxide from a carbon dioxide-containing gas, the method comprising: absorbing carbon dioxide from the carbon dioxide-containing gas in an absorber with a solvent to form a carbon dioxide-lean gas and a rich solvent, wherein the absorption of carbon dioxide generates absorption heat; transferring the absorption heat to a heating source; generating a heating stream from the heating source based at least in part on the absorption heat and primary heat provided by a first heater of the heating source; and desorbing carbon dioxide from the rich solvent in a regenerator with the heating stream.

13. The method of claim 12, comprising transferring pre-treatment heat from the carbon dioxide-containing gas to the heating source, wherein the heating stream is generated based at least in part on the absorption heat, the primary heat, and the pre-treatment heat.

14. The method of claim 12, comprising transferring the absorption heat via multiple interstage coolers of the absorber.

15. The method of claim 12, wherein a heat load ratio between the primary heat and the absorption heat is between 80:20 to 50:50.