Cryogenic-based carbon capture system and method

Abstract

Carbon capture for industrial applications, such as power plants, municipal solid waste facilities, cement production, iron & steel, petrochemicals, desalination and refineries, is disclosed herein. Embodiments employ a cryogenic system and process to capture carbon dioxide, ensuring efficient and effective capture, while also maximizing solvent recovery. This advancement enables a capability to meet the demands of diverse industries with a solution that reduces energy penalties and enhances overall operational efficiency. The approach is scalable, modular, and compact, while minimizing energy consumption.

Description

[0001] CRYOGENIC-BASED CARBON CAPTURE SYSTEM AND METHOD

[0002] BACKGROUND

[0003] Field of the Invention

[0004] The present disclosure relates generally to systems and processes for greenhouse gas, carbon dioxide (CO2), nitrogen oxides (NOX) and sulphur oxides (SOX) mitigation from various point source emissions. More particularly, the disclosure is directed to cryogenic-based carbon capture processes that provide comparatively low energy demand while maintaining large- scale applicability and system durability.

[0005] Background of the Invention

[0006] Climate change has been associated with significant environmental and socio-economic effects, influencing the lives and livelihoods of populations worldwide. Scientific consensus attributes a substantial portion of these effects to the accumulation of greenhouse gases (GHGs) in the atmosphere.

[0007] Numerous approaches have been developed for reducing or mitigating GHG emissions, including chemical absorption, adsorption, and membrane separation techniques. While these methods have achieved varying levels of success, many present limitations such as high energy consumption, material degradation, or scalability challenges.

[0008] Accordingly, there remains a need in the art for carbon capture processes that can be implemented on a large scale, with reduced energy requirements and improved operational robustness.

[0009] The present disclosure addresses these needs by providing a cryogenic-based carbon capture system and process that offers comparatively low energy demand while maintaining large-scale applicability and system durability.

[0010] SUMMARY

[0011] According to first broad aspect, the present disclosure provides a cryogenic-based carbon capture system, comprising: a cold box configured to maintain cryogenic conditions; a gas-gas heat exchanger disposed within the cold box, wherein the gas-gas heat exchanger is configured to receive dry flue gas and cool the flue gas to a temperature of approximately -90°C; a bubbling column positioned within the cold box, wherein the bubbling column is configured to receive the cooled flue gas stream from the gas-gas heat exchanger, wherein cryogenic carrier fluid (CCF) is disposed within the bubbling column; a gas distributor disposed at a base of the bubbling column to disperse the received cooled flue gas into the cryogenic carrier fluid as it bubbles; a stab-in cooler inserted within the bubbling column and configured to remove heat from the cryogenic carrier fluid to maintain a cryogenic temperature sufficient for CO2 desublimation; a filtration system fluidly connected to the bubbling column and configured to separate solid CO2 from the cryogenic carrier fluid; a melter vessel fluidly connected to the filtration system and configured to heat a CO2 solid-rich slurry to liquefy CO2; a cryogenic carrier fluid drum fluidly connected to the filtration system and the bubbling column and configured to recirculate the cryogenic fluid; and a recycle cooler fluidly connected to the bubbling column and the cryogenic carrier fluid drum and configured to cool a recycle stream comprising the cryogenic carrier fluid for reintroduction into the bubbling column.

[0012] According to a second broad aspect, the present disclosure provides a method of capturing carbon dioxide from a flue gas stream, the method comprising: receiving dry flue gas into a gas-gas heat exchanger and cooling the dry flue gas to a temperature of approximately -90°C; introducing the cooled dry flue gas into a bubbling column at the bottom section containing a cryogenic carrier fluid under cryogenic conditions; dispersing the cooled dry flue gas into the cryogenic carrier fluid as bubbles using a gas distributor; operating a stab-in cooler inserted into the bubbling column to maintain the cryogenic carrier fluid at a temperature sufficient for CO2 desublimation; accumulating solid CO2 within the cryogenic carrier fluid to form a CO2 solid-rich slurry; transferring the CO2 solid-rich slurry from the bubbling column to a filtration system; separating solid CO2 from the cryogenic carrier fluid within the filtration system; transferring the CO2 solid-rich slurry to a melter vessel and heating the slurry to liquefy the CO2 at a higher pressure; and routing a recycle stream comprising cryogenic carrier fluid through a recycle cooler for reintroduction into the bubbling column.

[0013] BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary embodiments of the invention, and, together with the general description given above and the detailed description given below, serve to explain the features of the invention.

[0015] FIG. l is a schematic illustration of a cryogenic-based carbon capture system, according to one embodiment of the present disclosure. FIG. 2 graphically illustrates CO2 capture efficiency as a function of temperature, according to one embodiment of the present disclosure.

[0016] FIG. 3 graphically illustrates the data at which the capture efficiency was recorded, according to one embodiment of the present disclosure.

[0017] DETAILED DESCRIPTION OF THE INVENTION

[0018] Definitions

[0019] Where the definition of terms departs from the commonly used meaning of the term, applicant intends to utilize the definitions provided below, unless specifically indicated.

[0020] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of any subject matter claimed. In this application, the use of the singular includes the plural unless specifically stated otherwise. It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. In this application, the use of “or” means “and / or” unless stated otherwise. Furthermore, use of the term “including” as well as other forms, such as “include”, “includes,” and “included,” is not limiting.

[0021] For purposes of the present disclosure, the term “comprising”, the term “having”, the term “including,” and variations of these words are intended to be open-ended and mean that there may be additional elements other than the listed elements.

[0022] For purposes of the present disclosure, directional terms such as “top,” “bottom,” “upper,” “lower,” “above,” “below,” “left,” “right,” “horizontal,” “vertical,” “up,” “down,” etc., are used merely for convenience in describing the various embodiments of the present disclosure. The embodiments of the present disclosure may be oriented in various ways. For example, the diagrams, apparatuses, etc., shown in the drawing figures may be flipped over, rotated by 90° in any direction, reversed, etc.

[0023] For purposes of the present disclosure, a value or property is “based” on a particular value, property, the satisfaction of a condition, or other factor, if that value is derived by performing a mathematical calculation or logical decision using that value, property or other factor.

[0024] For purposes of the present disclosure, it should be noted that to provide a more concise description, some of the quantitative expressions given herein are not qualified with the term “about.” It is understood that whether the term “about” is used explicitly or not, every quantity given herein is meant to refer to the actual given value, and it is also meant to refer to the approximation to such given value that would reasonably be inferred based on the ordinary skill in the art, including approximations due to the experimental and / or measurement conditions for such given value.

[0025] For purposes of the present disclosure, the term “2 x 100% configuration” refers to an arrangement in which two units of identical capacity are installed, each capable of handling the full design duty independently. One unit operates while the other is on standby (drain or fill mode), ensuring uninterrupted operation. In an exemplary embodiment, the second unit is on standby during continuous operation.

[0026] For purposes of the present disclosure, the term “annular space” refers to the area between two tanks in a double wall configuration, which can be affected by the entry of substances. In some embodiments, an annular space, or annulus, is the ring-shaped area or gap between two cylindrical objects, where one object is contained within the other. In the context of cryogenic and chemical processing equipment, the term annular space may refer to the ring-shaped gap formed between two concentric walls or vessels. For example, in a cryo-contactor or bubbling column, an annular space may be created between the inner process chamber and the surrounding outer shell. This space can be utilized for several functions, such as circulating a refrigerant to maintain cryogenic conditions, providing thermal insulation to minimize heat ingress, or routing secondary process streams that interact indirectly with the main fluid. By designing the equipment with an annular space, operators can achieve improved temperature control, enhanced process efficiency, and greater operational stability in gas-liquid separation or carbon capture applications.

[0027] For purposes of the present disclosure, the term “ambient conditions” refers to the surrounding environmental factors of a system or object. These factors may include temperature or room temperature, humidity, air pressure, light intensity, noise level, and vibration magnitude. They essentially describe the "background" conditions of an environment.

[0028] For purposes of the present disclosure, the term “ambient temperature” refers to a temperature of from about 20 °C to about 25 °C.

[0029] For purposes of the present disclosure, the term “bubbling column” refers to a vertical vessel configuration in which a gaseous stream is introduced at the base of the column and dispersed through a liquid medium. The rising gas bubbles promote mixing and maintain a high interfacial area between the gas and liquid phases, thereby enhancing both mass and heat transfer. The absence of internal moving components affords operational simplicity, robustness, and reduced maintenance requirements. The system is adaptable to various industrial applications, including chemical synthesis, biotechnological fermentation, and environmental gas absorption processes, such as carbon dioxide capture. The column configuration thereby offers a scalable and reliable means of effecting gas-liquid contact in a wide range of operating conditions. When used specifically as a reactor, the bubbling column may be referred to as a bubble column reactor.

[0030] For purposes of the present disclosure, the term “clean gas” refers to a portion of a flue gas stream remaining after removal of targeted contaminants (CO2 and other pollutants), consisting primarily of non-condensable components that remain in the permanent gas phase (N2, 02 etc.). Depending on the partial pressure of CO2 and the cryogenic operating temperature in the bubbling column, trace amounts of CO2 may remain in this stream.

[0031] For purposes of the present disclosure, the term “cold box” refers to a thermally insulated enclosure designed to maintain cryogenic temperatures necessary for efficient gas separation and CO2 desublimation and to minimize heat ingress. The disclosed cold box may be nonstandard and customized, where a combination of perlite and a flexible insulation blanket is used. The thickness of the flexible insulation blanket and the thickness of perlite filling may be calculated using a proprietary tool and based on the temperature difference between the set point of the equipment and ambient conditions.

[0032] For purposes of the present disclosure, the term “conduit” refers to channel, pipe, or protective casing used to convey a fluid or gas. Disclosed embodiments may include, for example, a physical object, like a pipe, tubing, channel or plumbing, often made of metal or plastic, used to convey fluids, gases, or other substances. In the disclosed system, a conduit may be considered as a pipe or tube that carries fluids / gases to transfer heat, serving as a vital component for directing hot and cold fluids / gases or mediating heat transfer.

[0033] For purposes of the present disclosure, the term “cryogenic” refers to extremely low- temperature conditions required to achieve efficient separation of CO2 from flue gas. These temperatures, often ranging from approximately -90 °C to -130 °C and extending to even colder ranges in some operations, enable CO2 to desublimate from the gas phase and accumulate as a solid within the cryogenic carrier fluid. Equipment such as the heat exchangers, bubbling column, and recycle cooler are specifically designed to maintain these cryogenic conditions, with insulated enclosures and specialized materials that prevent heat ingress from the environment. By sustaining this cryogenic environment, the system is able to reliably capture and process CO2 while ensuring stability, efficiency, and scalability of the overall separation process.

[0034] For purposes of the present disclosure, the term “cryogenic carrier fluid (CCF)” refers to a liquid with an extremely low boiling point that exists as a liquid at normal and cryogenic conditions. The CCF may be used to transport or sustain other materials at very cold, or cryogenic, temperatures. The CCF may itself be kept in a liquid state by maintaining these very low temperatures.

[0035] For purposes of the present disclosure, the term “desublimation” refers to the direct phase change of a substance from the gas phase to the solid phase without passing through the intermediate liquid phase. The process is also commonly known as deposition.

[0036] For purposes of the present disclosure, the term “greenhouse gases (GHGs)” refers to gases in the Earth's atmosphere that absorb and emit heat, trapping it near the surface and causing the planet to warm through the greenhouse effect. Key GHGs may include carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), as well as fluorinated gases. While a natural part of the atmosphere, activities, particularly the burning of fossil fuels for energy and transportation, may have dramatically increased their concentrations, amplifying the greenhouse effect and possibly contributing to driving a climate change effect.

[0037] For purposes of the present disclosure, the term “recycle cooler” refers to an apparatus configured to remove heat from a recycle stream z.e., liquid that has already passed through part of the system and is returned for additional processing. By lowering the temperature of the recycle stream, the cooler helps maintain the desired operating conditions within the main process equipment. In the solvent separation system, a recycle cooler may be employed to manage and maintain the cryogenic operating conditions required for efficient CO2 capture. During operation, a portion of the process stream, such as CCF , is redirected back into the system as a recycle stream. Before reentry, this recycle stream is routed through the recycle cooler, where it is chilled to the necessary cryogenic temperature. By reducing the thermal load of the recycled gas, the cooler ensures that the cold box and bubbling column remain within the optimal temperature range for CO2 desublimation. This approach improves energy efficiency by reusing internal process streams rather than relying exclusively on external refrigeration, while also stabilizing system performance by maintaining steady-state conditions during continuous or semi-batch operation.

[0038] For purposes of the present disclosure, the term “semi-batch process” refers to a process configuration in which a portion of the working medium, such as a CChrich slurry, is initially charged into a separation vessel to a predefined level and then separation initiated in a batch manner without any disruption of upstream and downstream operation In such configurations, the clean gas fraction may be continuously discharged, while the CO2 is selectively accumulated in the CCF in solid form. The accumulated slurry comprising the CCF and CO2 solids may then be withdrawn at the conclusion of the process or upon reaching a desired concentration. In this manner, the semi-batch process provides ample time for solid liquid separation without any impact on upstream CChcapture process and downstream CChpurification process while combining the advantages of batch operation (flexibility, controllability) and continuous operation (stability, efficiency). Injection and some steps in separation and downstream purification (not included here) may be continuous, while melting and some element of liquification may be batch processes.

[0039] For purposes of the present disclosure, the term “stab-in cooler” refers to a type of heat exchanger where a bundle of cooling tubes is directly inserted into the process vessel to transfer heat effectively. This design may be known as a stab-in bundle cooler. Unlike external heat exchangers that require separate circulation loops, the stab-in cooler may consist of a bundle of cooling tubes inserted directly — or “stabbed” — into the vessel so that they remain in direct contact with the process medium. This configuration enables efficient thermal exchange by allowing the process stream, such as CCh-rich slurry or carrier fluid, to flow around the cooled surfaces of the tubes. By integrating the cooler into the vessel itself, the system achieves simplified operation, reduced piping complexity, and consistent maintenance of the low- temperature environment required for CO2 capture and separation. The stab-in cooler may be equipped with a defrosting mechanism. The stab-in cooler has redundancy to ensure high performance continuous cooling.

[0040] Description

[0041] While the invention is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and the scope of the invention.

[0042] The present disclosure provides a cryogenic-based carbon capture system and process that offers comparatively low energy demand while maintaining large-scale applicability and system durability. The disclosed system and process provides a cryogenic-based approach to carbon capture that is capable of operating at industrial scale with comparatively low energy requirements. The system is configured to deliver robust performance while maintaining a compact design suitable for deployment in a range of industrial environments. The disclosed system and process is inherently safe and reliable, supporting continuous operation with a very high on-stream factor. The system design facilitates efficient recovery of solvents, while also minimizing fouling issues that are often encountered in conventional capture technologies. Maintenance considerations are incorporated into the design, allowing for convenient access and simplified cleaning procedures. The disclosed system and process is further characterized by flexibility in operation, enabling treatment of varying feed gas compositions without substantial modifications to the system. In addition, the technology is scalable, allowing adaptation from pilot to large-scale installations. From an economic perspective, the process is configured to provide favorable capital expenditure (CAPEX) and operating expenditure (OPEX) performance, supporting cost-effective deployment and long-term commercial viability.

[0043] FIG. l is a schematic illustration of a cryogenic-based carbon capture system, according to one embodiment of the present disclosure. The cryogenic-based carbon capture system utilizes the disclosed CO2 solvent separation system 10 which provides dry flue gas 12. In some disclosed embodiments dry flue gas 12 is approximately less than 1 ppm of water CO2 composition in the typical flue gas ranging from approximately 3-60% CO2 by volume. In the disclosed embodiment, the carbon capture efficiency can vary upwards from 90%. Dry flue gas 12 is configured to be operatively and fluidly connected, such as via connection line or conduit 14, to enter into a specially designed gas distributor.

[0044] The dry flue gas enters the gas-gas heat exchanger 16 where it is cooled up to approximately -90°C by exchanging heat from clean gas leaving from the top section of bubbling column 20. Gas-gas heat exchanger 16 may be operatively and fluidly connected, such as via connection line or conduit 18, to a cryo-contactor which, in the disclosed embodiment, may be regarded and function as a bubbling column 20. In some disclosed embodiments, gas from gas-gas heat exchanger 16 is configured to enter through the bottom of bubbling column 20, such as via connection line or conduit 18.

[0045] Bubbling column 20 may be retrofitted with a specially designed gas distributor (bubbler) 62 configured to uniformly distribute introduced flue gas across the cross-sectional area of the cryo-contactor or bubbling column 20. At the start of operation, the cryo-contactor (bubbling column 20) may be filled with cryogenic carrier fluid (CCF) up to a predefined level. The gas received from gas-gas heat exchanger 16 then bubbles through the CCF under cryogenic conditions via the specially designed gas distributor (bubbler) 62 positioned within bubbling column 20. In this manner, the dry, pre-cooled flue gas is caused to bubble through the cryogenic carrier fluid bath in the cryo-contactor via the specially designed gas distributor (bubbler) 62 at an approximate temperature of-130°C.

[0046] Operation of the bubbling column 20 demonstrates effective gas-liquid interaction through the use of the specially designed gas distributor (bubbler) 62 positioned at the bottom section of bubbling column 20. Specially designed gas distributor (bubbler) 62 introduces the flue gas into the liquid phase, generating a multitude of small rising bubbles that promotes uniform mixing throughout bubbling column 20. As the bubbles ascended, they enhanced mass transfer by facilitating dissolution and reaction of the flue gas within the liquid medium (cryogenic carrier fluid (CCF)). The rising bubbles also contribute to consistent thermal distribution, maintaining stable temperatures throughout the system. The resulting flow and mixing ensures that the liquid remains homogenous, while also allowing pressure and density measurements to provide reliable indicators of CO2 accumulation and slurry characteristics. Overall, the incorporation of the specially designed gas distributor (bubbler) 62 enables the bubbling column 20 to achieve efficient, controlled, and continuous gas-liquid processing.

[0047] An isolation valve 22 may be disposed along connection line or conduit 18, such as between gas-gas heat exchanger 16 and bubbling column 20, to regulate the gas supply to bubbling column 20. The temperature of the cryo-contactor is maintained between approximately - 125°C to -135°C depending on the flue gas composition and targeted CO2 capture efficiency greater that 90%. The cooling is accomplished by an integral stab-in cooler 24 submerged in the cryogenic carrier fluid bath. Stab-in cooler 24 may comprise a bundle of cooling tubes configured to be inserted directly into bubbling column 20 such that the tubes are in thermal contact with the process medium contained therein. . Stab-in cooler 24 may be further configured to remove heat from the cryogenic carrier fluid (CCF), thereby maintaining bubbling column 20 at cryogenic operating conditions required for the disclosed CO2 desublimation. By integrating stab-in cooler 24 within bubbling column 20, the disclosed embodiments may reduce external circulation requirements, simplify system architecture, and improve thermal efficiency. Bubbling column 20 may be equipped with a temperature reading monitor 130 used to observe the temperature therein. A temperature control valve 132 may be connected via connection line or conduit 124 to adjust the temperature of bubbling column 20, for example, by controlling the refrigerant flow rate through the tube side of stab-in cooler 24 via refrigerant return line 110.

[0048] The efficiency of carbon capture is a function of the carbon dioxide concentration in the flue gas as well as temperature of the CCF bath, which may range from approximately 3.5% CO2 to 60% CO2 or higher. In disclosed embodiments, capture efficiencies of 90% or greater are achievable. During operation, the CO2 present in the flue gas undergoes desublimation, forming solid CO2 particles that will saturate and accumulate within the cryogenic carrier fluid (CCF) bath. In disclosed embodiments, the bath typically reaches a solids concentration of about 50% to 60% CO2 by mass. The resulting slurry, comprising the CCF and the CO2 solids, is subsequently conveyed to a solid-liquid filtration system by means of a pump or gravity- driven transfer mechanism, as described below.

[0049] In certain preferred embodiments, bubbling column 20 is equipped with a liquid level controller 38, which may be connected by means of connection lines or conduits 40 and 42. The level controller 38 may control the flow of recycle cryogenic carrier fluid through valve 126 along connection line or conduit 106 (as further described below). The instrumentation associated with liquid level 38 may include a read-out display for monitoring variations in the liquid level within bubbling column 20 as carbon dioxide accumulates or desublimates, thereby causing the liquid level to rise. Accordingly, the liquid level within bubbling column 20 can be monitored and regulated based on the readings and data generated by level controller 38.

[0050] In an exemplary embodiment, bubbling column 20 may be equipped with a pressure reading monitor 48. Pressure reading monitor 48 may be connected via connection line or conduit 50, for example, tapped at the upper portion of bubbling column 20, and via connection line or conduit 52 routed to connection line or conduit 18. Readings from pressure reading monitor 48 provide information regarding the pressure drop across bubbling column 20, which reflects the density of the contents within the column. Changes in pressure over time correspond to variations in density as CO2 accumulates within CO2 solvent separation system 10. In certain embodiments, the measured density may be used to maintain the pressure of the inert gas and determine the concentration of CO2 within bubbling column 20. Connection line or conduit 58 is configured to supply clean gas at low temperatures, e.g., at approximately -100°C to -110°C, generally from a top of bubbling column 20 routed to gasgas heat exchanger 16. This gas will facilitate cooling down the incoming dry flue gas 12 into gas-gas heat exchanger 16. Connection line or conduit 60 is configured to supply cooled clean flue gas 116 from gas-gas heat exchanger 16 for usage in other disclosed systems.

[0051] In one exemplary embodiment, bubbling column 20 is operatively and fluidly connected to pump 28 or, alternatively, to a gravity -driven transfer mechanism through connection line or conduit 26. Pump 28 operates as a first pump in the disclosed CO2 solvent separation system 10 and may regarded as a first transfer pump and include a screw-driven design e.g., a single screw or a twin screw). A motor 30 may be utilized to drive pump 28. Pump 28 or the gravity- driven transfer mechanism is further connected, via connection line or conduit 32, to a filtration system 34. A valve 36 may be positioned along connection line or conduit 26, between bubbling column 20 and pump 28 or the gravity-driven transfer mechanism, to regulate the transfer of the slurry, comprising the CCF and CO2 solids, to filtration system 34.

[0052] Filtration system 34 may be regarded as a solid-liquid filtration system. In certain embodiments, filtration system 34 may comprise a cylindrical design 64 defining an internal annular space 66, wherein annular space 66 includes a perforated section, such as a mesh structure. The feed delivered via connection line or conduit 32 may be introduced into a middle section 68 of filtration system 34. During operation, the cryogenic carrier fluid (CCF) is configured to pass from middle section 68 into annular space 66 through the perforated section, while the solid material is generally retained within middle section 68. In this manner, filtration system 34 functions to effect separation of the liquid and solid phases, thereby enabling downstream processing of the separated CCF and / or sold material.

[0053] In certain embodiments, filtration system 34 (solid-liquid filtration system) may be configured to operate in a semi-batch / continuous operation process mode with a 2 x 100% configuration, such that the concentration of solid CO2 within the slurry is increased from an initial range of approximately 50% by mass to levels approaching or exceeding 90% by mass. Filtration system 34 may further be configured to separate and remove the cryogenic carrier fluid (CCF) from the incoming slurry mixture. For example, a hydraulic press 70 may be employed within filtration system 34 to press the received slurry feed within middle section 68 to effect separation of the liquid and solid phases. A motor 72 may be configured to power hydraulic press 70. Hydraulic press 70 operates as a plunger to push solid out of filtration system 34, and the liquid is configured to flow from the side, as described below. Accordingly, filtration system 34 functions as a solid / liquid separator, thereby concentrating the CO2 solids while recovering the CCF for reuse within the disclosed solvent separation system.

[0054] Filtration system 34 may be operatively and fluidly connected to a pump 74 through connection line or conduit 76. Pump 74 operates as a second pump in the disclosed CO2 solvent separation system 10 and may regarded as a second transfer pump. While FIG. 1 illustrates a single pump 74 connected to a single filtration system 34, it is readily appreciated that one or more pumps 74 may be employed and connected to one or more filtration systems 34, respectively, in the disclosed CO2 solvent separation system 10. A motor 78 may be configured to power pump 74. Pump 74 may be operatively and fluidly connected to melter vessel 80 through connection line or conduit 82. Thus, motor 78 may be actuated to power pump 74 to transfer the CO2 solid-rich slurry into melter vessel 80. While a single melter vessel 80 is illustrated in connection with a single filtration system 34, it is readily appreciated that one or more melter vessels 80 may be employed and connected to one or more filtration systems 34, respectively, in the disclosed CO2 solvent separation system 10.

[0055] Within melter vessel 80, the CO2 solid-rich slurry may be heated and self-pressurized to convert the solid phase CO2 into a liquefied state, thereby preparing the CO2 for subsequent processing, such as delivery to an advanced CO2 purification system 86, as further described herein. In certain embodiments, the slurry may enter melter vessel 80 at an inlet pressure of approximately 0-2 bar(g) and at a temperature of about -100°C to -110°C. Initial transfer can be gravity driven or may utilize driven transfer pump (pump 28). In some embodiments, the disclosed melting process may start at 9.5 barg. Pressure can be controlled using the disclosed pressure control system. Upon heating, the liquefied CO2 may be discharged from melter vessel 80 at an outlet pressure of approximately 9-10 barg and at a temperature of about -50°C to - 60°C. To maintain energy efficiency and facilitate melting within melter vessel 80, a process utility stream 120 from a CO2 purification section may be operatively and fluidly routed along connection line or conduit 122 and employed as a heating medium as well to provide additional heating, as required, at melter vessel 80. In some embodiments, process utility stream 120 may be directed through melter / heater unit 94 and its flow regulated by valve 96 prior to delivery to melter vessel 80. Process utility stream 120 may include a high purity CO2 gas phase that condenses to liquid CO2 after melter / heater unit 94.

[0056] In one embodiment, the liquified CO2 may be sent (e.g., via pump 84) to an advanced CO2 purification system 86 via connection lines or conduits 88 and 90, respectively. Pump 84 operates as a third pump in the disclosed CO2 solvent separation system 10 and may regarded as a CO2 pump.

[0057] In certain embodiments, liquefied CO2 may be rerouted to melter vessel 80 via connection line or conduit 92. A melter / heater unit 94 may be operatively and fluidly disposed along connection line or conduit 92 and configured to condition the liquefied CO2 as required prior to introduction into melter vessel 80. A valve 96 may be positioned along connection line or conduit 92, between melter / heater unit 94 and melter vessel 80, and may be configured to regulate the controlled transfer of liquefied CO2 from melter / heater unit 94 to melter vessel 80. In additional embodiments, liquefied CO2 may alternatively, or in combination, be directed through connection line or conduit 98 to a process outlet 100, whereupon, in some examples, the liquefied CO2 may be stored in cryogenic vessels and ready for transport for end use.

[0058] The disclosed embodiment may also provide a cryogenic carrier fluid (CCF) drum 102 in connection with filtration system 34 such as via connection line or conduit 134. Filtration system 34 may include a filter set 128 (dotted lines in FIG. 1) as part of a mesh filter comprising a combination of stainless steel fine mesh layers with a flexible filter medium positioned between them. Upon activation of hydraulic press 70 (described above), CCF is squeezed out from the mesh filter on the sides using a mechanical plunger. Recovered CCF is drained as a liquid from filtration system 34 at approximately at a temperature of about -100°C to -110°C and received into CCF drum 102 via connection line or conduit 134. A pump 104 may be employed to recirculate CCF back to bubbling column 20, as required, such as via connection line or conduit 106. Pump 104 operates as a fourth pump in the disclosed CO2 solvent separation system 10 and may regarded as a CCF pump. A recycle cooler 108 may be positioned along connection line or conduit 106, between CCF drum 102 and bubbling column 20, and may be configured to condition the CCF as required prior to introduction into bubbling column 20. Thus, the temperature of CCF and bubbler column 20 may be maintained through use of the disclosed recycle cooler 108. In maintaining the temperature of CCF and bubbler column 20, recycle cooler 108 may direct CCF to a refrigerant return 110, as necessary. In addition, a refrigerant supply 112 may be configured to provide refrigerant to bubbling column 20, such as via stab-in cooler 24, and recycle cooler 108, such as via connection line or conduit 114. Refrigeration for cryogenic cooling operation may be provided by closed loop liquid nitrogen systems or by closed loop mechanical refrigeration systems, including cascade cycles using single refrigerants (e.g., methane, propane, ethylene) or mixed refrigerant blends. While a single CCF drum 102 in combination with pump 104 is illustrated in connection with a single filtration system 34, it is readily appreciated that one or more CCF drums 102 in combination with pumps 104 may be employed and connected to one or more filtration systems 34, respectively, in the disclosed CO2 solvent separation system 10.

[0059] In some preferred embodiments, the entire disclosed CO2 solvent separation system 10 is enclosed in a proprietary customized cold box 118, designed to maintain temperature and minimize energy losses. During operation, incoming flue gas 12 is routed through cold box 118, where it is pre-cooled via internal heat exchangers and subsequently introduced into bubbling column 20. The cryogenic carrier fluid (CCF) within bubbling column 20 facilitates the accumulation of solid CO2, while the disclosed cold box ensures that all internal components, including the piping and exchangers, remain at sufficiently low temperatures to prevent heat ingress from the surroundings. This controlled cryogenic environment enables consistent CO2 capture and high separation efficiency. By consolidating the low-temperature operations within a single enclosure, cold box 118 serves both as a protective and functional component, optimizing thermal management and overall system performance. The heat of fusion of the CO2 is used to condensate the product stream, thus saving approximately 40% energy in the whole disclosed process.

[0060] Thus, in some disclosed embodiments, the present disclosure provides a cryogenic-based carbon capture system, comprising: a cold box configured to maintain cryogenic conditions; a gas-gas heat exchanger disposed within the cold box, wherein the gas-gas heat exchanger is configured to receive dry flue gas and cool the flue gas to a temperature of approximately - 90°C; a bubbling column positioned within the cold box, wherein the bubbling column is configured to receive the cooled flue gas stream from the gas-gas heat exchanger, wherein cryogenic carrier fluid (CCF) is disposed within the bubbling column; a gas distributor disposed at of the bubbling column to disperse the received cooled flue gas into the cryogenic carrier fluid as it bubbles; a stab-in cooler inserted within the bubbling column and configured to remove heat from the cryogenic carrier fluid to maintain a cryogenic temperature sufficient for CO2 desublimation; a filtration system fluidly connected to the downstream of bubbling column and configured to separate solid CO2 from the cryogenic carrier fluid; a melter vessel fluidly connected to the filtration system via Transfer pump and configured to heat a CO2 solidrich slurry to liquefy CO2; a cryogenic carrier fluid drum fluidly connected to the filtration system act as a buffer drum to recirculate the cryogenic fluid to the bubbling column via CCF pump and a recycle cooler connected to the cryogenic carrier fluid drum to the bubbling column and configured to cool a recycle stream comprising the cryogenic carrier fluid for reintroduction into the bubbling column.

[0061] The present disclosure also provides a method of capturing carbon dioxide from a flue gas stream, the method comprising: receiving dry flue gas into a gas-gas heat exchanger and cooling the dry flue gas to a temperature of approximately -90°C; introducing the cooled dry flue gas into a bubbling column at the bottom section containing a cryogenic carrier fluid under cryogenic conditions; dispersing the cooled dry flue gas into the cryogenic carrier fluid as bubbles using a gas distributor; operating a stab-in cooler inserted into the bubbling column to maintain the cryogenic carrier fluid at a temperature sufficient for CO2 desublimation; accumulating solid CO2 within the cryogenic carrier fluid to form a CO2 solid-rich slurry; transferring the CO2 solid-rich slurry from the bubbling column to a filtration system; separating solid CO2 from the cryogenic carrier fluid within the filtration system; transferring the CO2 solid-rich slurry to a melter vessel and heating the slurry to liquefy the CO2 at a higher pressure; and routing a recycle stream comprising cryogenic carrier fluid through a recycle cooler for reintroduction into the bubbling column.

[0062] Having described the many embodiments of the present disclosure in detail, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims. Furthermore, it should be appreciated that all examples in the present disclosure, while illustrating many embodiments of the invention, are provided as nonlimiting examples and are, therefore, not to be taken as limiting the various aspects so illustrated.

[0063] EXAMPLES

[0064] FIG. 2 graphically illustrates CO2 capture efficiency as a function of temperature, according to one embodiment of the present disclosure. Disclosed embodiments conducted a test at a 20% CO2 concentration using a cryogenic bubbler column filled with a carrier fluid. The disclosed system was cooled down to a set point of -120 °C at which the disclosed theory suggests exemplary embodiments should be above 90% CO2 capture efficiency.

[0065] FIG. 3 graphically illustrates the data at which the capture efficiency was recorded, according to one embodiment of the present disclosure. A test was conducted using the disclosed bubbler column without the stab-in cooler to evaluate the baseline capture performance at -120 °C and compare it to the theoretical graph at 20% CO2. During CO2 injection, the disclosed system achieved -89% capture efficiency, with the cryogenic carrier fluid (CCF) gradually warming as CO2 solidified, consistent with theoretical predictions. This confirms that significant capture efficiency can be achieved using the disclosed bubbler column. The inclusion of the disclosed stab-in cooler to actively maintain the target temperature would be expected to sustain > 90% capture and further enhance performance, enabling capture efficiencies exceeding 95% at lower operating temperatures.

[0066] All documents, patents, j oumal articles and other materials cited in the present application are incorporated herein by reference.

[0067] While the present disclosure has been disclosed with references to certain embodiments, numerous modification, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present disclosure, as defined in the appended claims. Accordingly, it is intended that the present disclosure not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.

Claims

WHAT IS CLAIMED IS:

1. A cryogenic-based carbon capture system, comprising: a cold box configured to maintain cryogenic conditions; a gas-gas heat exchanger disposed within the cold box, wherein the gas-gas heat exchanger is configured to receive dry flue gas and cool the flue gas to a temperature of approximately -90°C; a bubbling column positioned within the cold box, wherein the bubbling column is configured to receive the cooled flue gas stream from the gas-gas heat exchanger, wherein cryogenic carrier fluid (CCF) is disposed within the bubbling column; a gas distributor disposed at a base of the bubbling column to disperse the received cooled flue gas into the cryogenic carrier fluid as it bubbles; a stab-in cooler inserted within the bubbling column and configured to remove heat from the cryogenic carrier fluid to maintain a cryogenic temperature sufficient for CO2 desublimation; a filtration system fluidly connected to the bubbling column and configured to separate solid CO2 from the cryogenic carrier fluid; a melter vessel fluidly connected to the filtration system and configured to heat a CO2 solid-rich slurry to liquefy CO2; a cryogenic carrier fluid drum fluidly connected to the filtration system and the bubbling column and configured to recirculate the cryogenic fluid; and a recycle cooler fluidly connected to the bubbling column and the cryogenic carrier fluid drum and configured to cool a recycle stream comprising the cryogenic carrier fluid for reintroduction into the bubbling column.

2. The system of claim 1, wherein the bubbling column comprises a liquid level transmitter configured to monitor accumulation of CO2 solids in the cryogenic carrier fluid.

3. The system of claim 1, wherein the bubbling column comprises a pressure reading monitor configured to measure pressure drop across the column, thereby determining slurry density and CO2 concentration.

4. The system of claim 1, wherein the filtration system comprises an annular space defining a perforated section configured to retain solid CO2 while allowing liquid cryogenic carrier fluid to pass into the annular space.

5. The system of claim 1, wherein the filtration system comprises a hydraulic press configured to compact the CO2 solid-rich slurry to separate liquid cryogenic carrier fluid from solid CO2.

6. The system of claim 1, wherein the melter vessel is configured to heat the CO2 solidrich slurry to a temperature between -60 °C and -50 °C at a pressure between 9 bar and 10 bar.

7. The system of claim 1, wherein the cold box encloses a gas-gas heat exchanger, the bubbling column, the stab-in cooler, the cryogenic carrier fluid drum, the recycle cooler, and associated conduits to maintain a cryogenic environment and minimize heat ingress.

8. The system of claim 1, wherein the recycle cooler is configured to direct excess heat to a refrigerant return line.

9. The system of claim 1, further comprising a pump configured to transfer the CO2 solidrich slurry from the bubbling column to the filtration system.

10. The system of claim 1, wherein the bubbling column is configured to operate at a temperature of approximately -125 °C to -135 °C and achieve a CO2 capture efficiency of at least 90% or greater.

11. The system of claim 1, wherein the carbon dioxide concentration in the dry flue gas, ranges from approximately 3.5% CO2 to 20% CO2.

12. A method of capturing carbon dioxide from a flue gas stream, the method comprising: receiving dry flue gas into a gas-gas heat exchanger and cooling the dry flue gas to a temperature of approximately -90°C; introducing the cooled dry flue gas into a bubbling column containing a cryogenic carrier fluid under cryogenic conditions; dispersing the cooled dry flue gas into the cryogenic carrier fluid as bubbles using a gas distributor;operating a stab-in cooler inserted into the bubbling column to maintain the cryogenic carrier fluid at a temperature sufficient for CO2 desublimation; accumulating solid CO2 within the cryogenic carrier fluid to form a CO2 solid-rich slurry; transferring the CO2 solid-rich slurry from the bubbling column to a filtration system; separating solid CO2 from the cryogenic carrier fluid within the filtration system; transferring the CO2 solid-rich slurry to a melter vessel and heating the slurry to liquefy the CO2 at a higher pressure; and routing a recycle stream comprising cryogenic carrier fluid through a recycle cooler for reintroduction into the bubbling column.

13. The method of claim 12, further comprising monitoring liquid level within the bubbling column to regulate operation as CO2 accumulates.

14. The method of claim 12, further comprising monitoring pressure drop across the bubbling column to determine density and CO2 concentration.

15. The method of claim 12, wherein separating solid CO2 comprises pressing the CO2 solid-rich slurry with a hydraulic press to remove liquid cryogenic carrier fluid.

16. The method of claim 12, wherein heating the slurry in the melter vessel produces liquefied CO2 at a pressure of about 9-10 bar and a temperature of -50 °C to -60 °C.

17. The method of claim 12, wherein operating the bubbling column achieves a CO2 capture efficiency of at least 90%.

18. The method of claim 12, wherein the recycle cooler directs excess heat to a refrigerant return line.

19. The method of claim 12, further comprising enclosing the gas-gas heat exchanger, the bubbling column, the stab-in cooler, the recycle cooler, and conduits within a cold box to maintain a cryogenic environment and minimize heat ingress.

20. The method of claim 12, wherein CCF is recovered from the melter vessel for reintroduction back into the bubbling column or for utilization in another system process.

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