Vapor compression for regeneration of trapping media in the presence of dense trapped target gas

Abstract

A process for regenerating a trapping medium rich in a trapped target gas, comprising: using thermal energy to heat a target gas rich trapping medium comprising an absorbent medium, an absorbed target gas, and water, thereby facilitating separation of the absorbed target gas from the trapping medium into a gas-containing vapor phase and a heated lean trapping medium, the gas-containing vapor phase comprising the target gas having a water vapor fraction of at least 0.8 and water vapor; compressing at least one of the gas-containing vapor phase or a vapor phase thermally associated with the gas-containing vapor phase to form a compressed vapor; heating the target gas rich entrapment medium using compressed steam as a thermal energy source; A process is provided that includes:

Description

[Technical field]

[0001] Priority Cross Reference This patent application claims priority from Australian Provisional Patent Application No. 2022900421, filed on 23 February 2022, the contents of which are to be understood as incorporated herein by reference.

[0002] The present invention relates to a vapor compression system that provides the necessary heat energy for the regeneration of a capture medium rich in a captured target gas. The present invention relates to an acid gas capture / removal process, such as for the removal of carbon dioxide (CO 2 ) capture, and it will be convenient hereinafter to disclose the invention with respect to that exemplary application. However, it should be understood that the invention is not limited to that application and may be used in a variety of target gas capture and / or removal processes. [Background technology]

[0003] The following discussion of the background of the invention is intended to facilitate an understanding of the present invention, but it should be understood that this discussion does not constitute an admission or acknowledgement that any of the material referred to was published, known, or part of the common general knowledge as of the priority date of this application.

[0004] CO 2 The leading technology for capture is low-temperature CO 2 absorbs CO at high temperatures as a result of heat input 2 Conventionally, the heat requirement for the regeneration process is met by the use of a liquid absorbent, e.g., an amine solution, which releases CO 2 It is filled by steam extracted from the steam cycle in the case of capture or provided by a separate boiler, or by heat available from another source.

[0005] Many other predecessors2 The capture process uses compression of the vapor stream from the desorber with subsequent heat recovery to remove CO 2 Reduce the heat energy requirements for desorption: A number of these process modifications incorporate compression of vapors from either the loaded (rich) or regenerated (lean) absorbent solution, resulting in a significant reduction in the heat requirements for the regeneration process.

[0006] WO2011 / 073672A1 describes an example of a system for regeneration of a capture medium rich in capture target gas that uses a combination of heat energy from vapor pressure and a heat pump that recovers heat energy from one or more low-grade heat sources from several points in the capture process to heat the gas rich capture medium to provide the heat energy required to dissociate it into a gas rich vapour phase and a lean absorbent solution. Although vapor compression can be used to provide some of the heat energy required to heat the rich absorbent solution in the reboiler, the process of WO2011 / 073672A1 requires the use of additional energy inputs to fully meet the energy requirements of the reboiler.

[0007] Another example is described in US Patent Publication No. 20160001223A1, which teaches a carbon dioxide capture system including a regenerator arrangement that includes a compression-driven energy recycle system connected to the top outlet of the regenerator. The compression-driven energy recycle system improves heat recovery efficiency by directly compressing the recovery gas exiting the regenerator without undergoing gas condensation and water vapor separation by a cooling process. However, the compression-driven energy recycle system is not configured to provide all the energy required for the reboiler function at the base of the regenerator. Additional energy must be provided to the reboiler by a water steam heater / reboiler.

[0008] Thus, although previous process modifications such as those detailed in WO2011 / 073672A1 and U.S. Patent Publication No. US20160001223(A1) have shown some energy savings through vapor compression and waste heat energy harvesting in the process, none of these processes provide a system that effectively utilizes the available energy that can be derived from the vapor compression system. In order to achieve an energy balance for the desorber, these systems require sourcing additional heat energy from process lines or systems that are remote from the desorption process and equipment.

[0009] It would therefore be desirable to provide a new or improved process for regenerating liquid absorbents that more efficiently recovers heat from vapor compression systems for use in regenerating the liquid absorbent. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] WO2011 / 073672A1 [Patent Document 2] U.S. Patent Publication No. 20160001223(A1) [Patent Document 3] U.S. Patent No. 10,040,023 [Patent Document 4] Australian Patent No. AU552657B2 [Patent Document 5] U.S. Patent No. US2,176,441 [Patent Document 6] Canadian Patent No. CA619,193 Summary of the Invention [Means for solving the problem]

[0011] A first aspect of the present invention provides a process for regenerating a trapping medium enriched with a trapped target gas, comprising: using thermal energy to heat the absorbent medium, the absorbed target gas, and the target gas rich trapping medium comprising water, thereby facilitating separation of the absorbed target gas from the trapping medium into a gas containing vapour phase and a heated lean trapping medium, the gas containing vapour phase comprising the target gas having a water vapor fraction of at least 0.8 and water vapor; compressing at least one of the gas-containing vapor phase or a vapor phase thermally associated with the gas-containing vapor phase to form a compressed vapor; heating the target gas rich entrapment medium using the compressed steam as a thermal energy source; Includes.

[0012] Thus, the present invention provides a CO 2 The present invention provides a process / system for the regeneration of a trapping medium, such as a liquid sorbent, used to trap a target such as a target gas. The heat recovery is utilized in a heating step of the process to facilitate separation of the absorbed target gas from the trapping medium into a gas-containing vapor phase and a heated lean trapping medium. As will now be described in more detail, depending on the process embodiment, the heat may be used to preheat the target gas rich trapping medium and / or to heat the trapping medium in the desorber (e.g., using a reboiler) through which the target gas rich trapping medium is heated via heat transfer in the desorber.

[0013] The vapor compression process of the present invention is based on the high vapor content of the gas stream exiting the absorption liquid regeneration process. This is contrary to conventional regeneration process designs that strive to minimize the vapor content as it typically results in energy losses. Such a conventional energy-efficient liquid regeneration process concept is 2 Wet CO leaving the desorber 2Based on minimizing the moisture content of the product, these regenerative process designs completely fail to recognize the advantages of vapor compression processes having high vapor content.

[0014] Nevertheless, it should be understood that the process of the present invention preferably does not have a significantly high steam content. At high water vapor fractions, the total amount of gas / steam is large. This is because the amount of captured CO 2 This increases the energy of compression per unit of steam, but also increases the amount of energy that can be recovered. The amount of energy recovered should be such that it is sufficient to provide the thermal energy for regeneration, but not more. Thus, there is a sweet spot within the range of steam fractions that can be used. It will be understood that the steam fraction is the fraction of water vapor (steam) in the overall steam / gas mixture.

[0015] Thus, in the present invention, the water vapor fraction in the outlet stream of the target gas separator must be high enough to allow significant recovery of latent heat in addition to recovery of sensible heat. The inventors have found that this requires a water vapor fraction of at least 0.8, preferably greater than 0.85, and more preferably greater than 0.9. The inventors are not aware of any prior art arrangements that include these uniquely advantageous process conditions that utilize this particular water vapor fraction range in the outlet stream of the target gas separator to provide more effective heat recovery for the vapor compression step (vapor compression energy recovery system). In an embodiment, the gas-containing vapor phase includes target gas and water vapor with a water vapor fraction between 0.8 and 0.999. In an embodiment, the gas-containing vapor phase includes target gas and water vapor with a water vapor fraction between 0.8 and 0.999, more preferably between 0.8 and 0.99, and even more preferably between 0.9 and 0.99. In some embodiments, the target gas and water vapor have a water vapor fraction between 0.9 and 0.999, preferably between 0.95 and 0.999. In some embodiments, the target gas and water vapor have a water vapor fraction between 0.8 and 0.995, preferably between 0.9 and 0.995. In embodiments, the gas-containing gas phase comprises a target gas and water vapor having a water vapor fraction of at least 0.9.

[0016] The required amount of water vapor in the gas-containing gas phase can be expressed as the water vapor to target gas ratio. In this context, the gas-containing gas phase containing the target gas and water vapor preferably has a water vapor / target gas ratio of at least 4, more preferably at least 8, and even more preferably at least 10. In an embodiment, the water vapor / target gas ratio is preferably 4 to 1000.

[0017] The vapor compression component of the process of the present invention relies on a high vapor content in the exhaust vapor stream which is then compressed with heat recovery in a regenerative process that allows for more efficient heat recovery from the compressed vapor. It should be understood that the process / system of the present invention still requires an external energy input to run the vapor compression system; here, electrical power may be used to run the compressor. This process is therefore a liquid absorbent based CO 2 It allows the use of electricity to perform heat absorption liquid regeneration in the capture process, which is particularly useful for direct air capture, which can then be run entirely on renewable energy, and advantageously avoids using heat for liquid absorbent regeneration, which may not be available in the process, adjacent processes, or the surrounding environment / industry.

[0018] The absorbed target gas can be separated from the target gas trapping medium using any suitable process and process vessel. In an embodiment, the step of separating the absorbed target gas from the trapping medium into a gas-containing gas phase is carried out in one of a flash vessel (or flash vaporization vessel) or a desorption vessel. Thus, in this step, the separation or desorption process can include one of flash vaporization, vaporization, boiling, stripping, or a combination thereof.

[0019] The heat balance of the absorption fluid regeneration / desorption process can be improved through heat exchange between various high-temperature and low-temperature process streams in the system. In most absorption fluid regeneration systems, the heat energy of the heated lean trapping medium is used as a heat energy source to heat a lower temperature process flow / line, such as the target gas rich trapping medium. In an embodiment, compressed steam is used as a first heat energy source to provide the energy required to heat the target gas rich trapping medium, and the heated lean trapping medium is used as a second heat energy source to provide the energy required to heat the target gas rich trapping medium. In this embodiment, the heat energy required for the regeneration process is provided by the heat energy in the desorption process, more specifically the vapor compression process. The first heat energy source and the second heat energy source preferably provide substantially all of the heat energy required to heat the target gas rich trapping medium. In this regard, the thermal energy required to heat the target gas rich trapping medium is preferably provided substantially by the first thermal energy source in combination with the second thermal energy source, and in some embodiments consists solely of the first thermal energy source in combination with the second thermal energy source.

[0020] The use of these different types of desorption processes and / or process vessels can result in variations of the process of the present invention adapted to the process vessel.

[0021] For example, in an embodiment where the process includes a flash vaporization vessel, the process of regenerating the trapping medium rich in trapped target gas may include: using thermal energy to heat the absorbent medium, the absorbed target gas, and the target gas-rich trapping medium comprising water, thereby facilitating separation of the absorbed target gas from the trapping medium into a gas-containing vapor phase and a heated lean trapping medium via flash vaporization in a flash vessel, the gas-containing vapor phase comprising the target gas having a water vapor fraction of at least 0.8 and water vapor; compressing the gas-containing vapor phase to form a compressed vapor; using compressed steam as a thermal energy source to preheat the target gas rich capture medium prior to being pumped into the flash vessel; may include.

[0022] In this embodiment, the process typically comprises: Also included is the step of using the heated lean trapping medium to preheat the target gas rich trapping medium before it is fed to the flash vessel.

[0023] In some embodiments, the desorption vessel includes a reboiler, in which compressed steam is used to heat the target gas rich trapping medium, where the compressed steam is used to heat the trapping medium in the desorber through which the target gas rich trapping medium is heated via heat transfer in the desorber. The gas-containing vapor phase can be used as a heat transfer medium / thermal working fluid in the reboiler to heat the trapping medium therein (direct heat exchange), or can be used indirectly, where the gas-containing vapor phase is used to heat another heat transfer medium / thermal working fluid that is then used in the reboiler to heat the trapping medium therein (indirect heat exchange).

[0024] For example, in an embodiment in which direct heat exchange with a gas-containing vapor phase is contemplated, the process includes a desorber vessel / column having a reboiler used to heat the trapping medium, typically lean trapping medium, at the bottom of the desorber vessel / column, and the process of regeneration of the trapping medium rich in the trapped target gas comprises: using thermal energy to heat the absorbent medium, the absorbed target gas, and the target gas rich trapping medium comprising water, thereby facilitating separation of the absorbed target gas from the trapping medium into a gas-containing vapor phase and a heated lean trapping medium in a desorber vessel, the gas-containing vapor phase comprising the target gas having a water vapor fraction of at least 0.8 and water vapor; compressing the gas-containing vapor phase to form a compressed vapor; pumping compressed steam into a reboiler for use as a thermal energy source to heat the target gas rich capture medium; may include.

[0025] In this embodiment, the process typically comprises: Also included is the step of using the heated lean trapping medium to preheat the target gas rich trapping medium before it is fed into the desorber vessel.

[0026] It should be understood that the compression step can be applied directly to the gas-containing gas phase formed through the separation of the absorbed target gas from the trapping medium into a gas-containing gas phase as described above, and / or can also be used to compress a gas phase thermally associated with the gas-containing gas phase to form a compressed vapor. In most processes, the compression step is applied directly to the gas-containing gas phase or a gas phase thermally associated with the gas-containing gas phase. However, it should also be understood that the process can include two parallel compression steps in which both the gas-containing gas phase or a gas phase thermally associated with the gas-containing gas phase undergo a compression step.

[0027] For indirect heat exchange, the thermal working fluid is preferably heated by a gas containing vapour to produce a gas phase thermally associated with the gas containing vapour phase. The working fluid is preferably selected as a medium capable of undergoing a phase change, i.e., vaporising upon heat transfer. It can then be compressed with heat recovery by condensation. In these embodiments, the process further comprises the step of heating a heat transfer fluid using the gas containing vapour phase to produce said heated heat transfer fluid. Any suitable thermal working fluid can be used. In a preferred embodiment, the thermal working fluid comprises a water rich phase capable of producing a steam / water vapour phase. Here, the process further comprises the step of heating the water rich phase using the gas containing vapour phase to produce said steam vapour phase. In these embodiments, the gas containing vapour phase is used to heat the water / water vapour, which is then used in a reboiler to heat the entrapment medium therein. Again, water / water vapour / steam is a convenient indirect thermal working fluid, but it should be understood that other working fluids can equally be used.

[0028] In one example of this embodiment, the process includes a desorber vessel / column having a reboiler used to heat the trapping medium, typically lean trapping medium, at the bottom of the desorber vessel / column, and compressed steam comprising water vapor heated from a gas-containing vapor phase. In these embodiments, the process of regeneration of the trapping medium rich in the trapped target gas comprises: using thermal energy to heat the absorbent medium, the absorbed target gas, and the target gas rich trapping medium comprising water, thereby facilitating separation of the absorbed target gas from the trapping medium into a gas-containing vapor phase and a heated lean trapping medium in a desorber vessel, the gas-containing vapor phase comprising the target gas having a water vapor fraction of at least 0.8 and water vapor; heating the water and / or water vapor phase to generate a water vapor phase using a gas-containing vapor phase; compressing the water vapor phase to form compressed vapor; pumping compressed steam into a reboiler for use as a thermal energy source to heat the target gas rich capture medium; may include.

[0029] In this embodiment, the process typically comprises: Also included is the step of using the heated lean trapping medium to preheat the target gas rich trapping medium before it is fed into the desorber vessel.

[0030] The water-rich phase may be heated by the gas-containing vapor phase using any number of heat exchange arrangements. In embodiments, the water-rich phase is Thermal exchange with a gas-containing vapor phase, or Mixing or otherwise contacting a gas-containing vapor phase with a water-rich phase It is heated using

[0031] In a thermal heat exchange embodiment, the compressed steam is cooled by heat exchange against water to heat the water and generate steam, which is used to provide thermal energy to heat the target gas rich entrapment medium.

[0032] Similarly, the compressed steam may be used to heat the target gas rich entrapment medium / entrapment medium using any number of heat exchange arrangements. Heat transfer may occur through thermal heat exchange (sensible or latent heat exchange via conduction, convection, or radiative heat exchange). For latent heat exchange (phase change heat exchange), this is preferably through heat of condensation. In an embodiment, the compressed steam is Thermal heat exchange with a target gas rich trapping medium, or Condensation heat exchange with a target gas-rich trapping medium which is then used to generate a condensed target gas and water phase and heat the target gas rich trapping medium.

[0033] Further thermal efficiency can be achieved by utilizing heat from additional process streams associated with the separation or desorption process vessel. In some embodiments, the process can further include using the condensed target gas and aqueous phase as an additional thermal energy source for heating the target gas rich entrapment medium. In these embodiments, the condensed target gas and aqueous phase composition can include a content of entrapment medium. The process can further include separating the entrapment medium from the target gas and aqueous phase to form a separated entrapment medium. The separated entrapment medium is preferably mixed with the heated lean entrapment medium.

[0034] The water vapor phase is not necessarily used in heat exchange with the target gas rich trapping medium in a reboiler or other heat exchange vessel. In embodiments, the compressed steam is used to heat the target gas rich trapping medium by pumping the compressed steam into the target gas rich trapping medium. In these embodiments, the compressed steam typically comprises a gas phase in thermal association with the gas-containing steam, which in an exemplary embodiment is water vapor / steam.

[0035] Here, the heat transfer is into the target gas rich trapping medium through direct mixing of the heated medium. For example, compressed steam can be mixed with the trapping medium in the process vessel to heat the trapping medium. If the process vessel is a desorber, the compressed steam can be pumped, mixed or injected into the trapping medium in the desorber or in a process volume fluidly connected to the desorber. Thus, in those embodiments in which the gas phase thermally associated with the gas-containing gas phase includes a water vapor phase, the water vapor phase can be pumped into the target gas rich trapping medium, thereby directly heating the target gas rich trapping medium.

[0036] An example of this mixed heating embodiment of the process includes a desorber vessel / column that is heated by a water vapor gas phase. In such an embodiment, the process of regeneration of the trapping medium rich in the trapped target gas comprises: using thermal energy to heat the absorbent medium, the absorbed target gas, and the target gas rich trapping medium comprising water, thereby facilitating separation of the absorbed target gas from the trapping medium into a gas-containing vapor phase and a heated lean trapping medium in a desorber vessel, the gas-containing vapor phase comprising the target gas having a water vapor fraction of at least 0.8 and water vapor; heating the water and / or water vapor phase to generate a water vapor phase using a gas-containing vapor phase; compressing the water vapor phase to form compressed vapor; pumping compressed steam into the desorber vessel to heat the target gas rich capture medium; may include.

[0037] In this embodiment, the process typically comprises: Also included is the step of using the heated lean trapping medium to preheat the target gas rich trapping medium before it is fed into the desorber vessel.

[0038] The heated lean trapping medium is used to heat the target gas rich trapping medium using any number of heat exchange arrangements, including direct and indirect heat exchange configurations. In an embodiment, the heated lean trapping medium is Heat exchange with a target gas rich trapping medium, or Heat exchange with a heat transfer medium that transfers heat to a target gas rich trapping medium is used to heat the target gas rich trapping medium.

[0039] The compression step may be carried out using any suitable compression arrangement and method. Thus, the compression step may include a single compression stage or multiple compression stages. When the compression step includes multiple compression stages, heat is preferably recovered between each compression stage using at least one intercooler disposed therebetween. Each compression stage preferably has a compression ratio between 1.1 and 10. It should be understood that the compression ratio depends on the compressor used in the process (and therefore commercially available). Within the range of 0.8 to 0.999 water vapor fraction in the outlet stream, the higher the compression ratio, the more sensible heat is generated, and is most effective in the lower zone range, while a low compression ratio is most effective in the higher zone range. These considerations may be overridden by the need to supply the target gas at high pressure, in which case a high compression ratio is desirable regardless of the water vapor fraction. This is because the target gas, e.g., CO 2 This is the case when some CO is sent for transport as a supercritical liquid to a geological repository. 2 Use is compressed CO for compression 2 Because CO 2 It may be advantageous to start compression already at the desorber outlet.

[0040] The absorbent medium of the acquisition medium may comprise any suitable absorbent fluid. In an embodiment, the absorbent medium comprises: a salt solution, i.e. a solution without vapour pressure, preferably an alkali salt solution or an amino acid salt solution, or CO in a gas-rich capture medium 2 Amine solutions with amine vapor pressures that are less than 10% of the partial pressure Includes at least one of the following:

[0041] The presence of significant amine vapors results in CO 2 and amines into the condensate, resulting in the production of CO due to reactions with the amines. 2 It should be understood that partial removal of CO occurs. However, the inventors believe that the amine vapor pressure is2 It has been found that this loss is acceptable if it is small compared to the pressure, for example 10%.

[0042] In an embodiment, the absorption medium comprises an alkali salt and a salt of an amino acid. Illustrative examples include potassium, lithium, and sodium salts of carbonate, glycine, tau acid, alanine, sarcosine, protease, lysine, methyltau acid, methionine, aminohexanoic acid, phenylalanine, glutamic acid, arginine aspartic acid, leucine, selenite, threonine, glucosamine, dimethylglycine, methylaminopropionic acid, aminobutyric acid, pipeco acid, preferably having a concentration between 0.005 and 5.0 M, more preferably between 0.5 and 2.5 M.

[0043] Finally, the target gas may include any desired gas that may be absorbed in an absorbing fluid, preferably an absorbing liquid. The target gas is typically CO 2 , H 2 S, HCl, HF, SO 2 , S.O. 3 OR NO x In many embodiments, the target gas includes an acid gas, such as at least one of carbon dioxide (CO 2 ).

[0044] A second aspect of the present invention provides a process for removing and recovering a target gas from a gas stream, comprising: absorbing a target gas from the feed gas stream into the trapping medium by passing the feed gas stream through a lean trapping medium, thereby causing a target gas component of the gas stream to be absorbed into the trapping medium to produce a target gas rich trapping medium; treating a target gas rich entrapment medium according to the process of the first aspect of the present invention; Includes.

[0045] A third aspect of the present invention provides an apparatus for regenerating a trapping medium enriched with a trapped target gas and recovering the trapped gas therefrom, comprising: a process vessel including a process volume; a supply conduit for delivering a gas-rich entrapment medium into the process volume; at least one heating arrangement configured to heat the target gas rich trapping medium to a temperature that facilitates separation of the absorbed target gas from the trapping medium into a gas-containing vapor phase comprising the target gas and water vapor having a water vapor fraction of at least 0.8 to produce a heated lean trapping medium; a vapor recompression system fluidly connected to the process volume, the vapor recompression system receiving and compressing a gas-containing vapor phase from at least one of the process volume or a vapor phase thermally associated with the gas-containing vapor phase to form a compressed vapor; a compressed steam supply conduit for supplying compressed steam to the at least one heating arrangement as a thermal energy source for heating the target gas rich capture medium; Equipped with.

[0046] As in the first aspect, the apparatus utilizes a high water vapor fraction in the outlet stream of the process vessel that is high enough to allow significant recovery of latent heat in addition to recovery of sensible heat. The inventors have found that this requires a water vapor fraction of at least 0.8, preferably greater than 0.85, more preferably greater than 0.9. In an embodiment, the gas-containing vapor phase comprises a target gas and water vapor having a water vapor fraction between 0.8 and 0.999. In an embodiment, the gas-containing vapor phase comprises a target gas and water vapor having a water vapor fraction between 0.8 and 0.999, more preferably between 0.8 and 0.99, even more preferably between 0.9 and 0.99. In some embodiments, the target gas and water vapor have a water vapor fraction between 0.9 and 0.999, preferably between 0.95 and 0.999. In some embodiments, the target gas and water vapor have a water vapor fraction between 0.8 and 0.995, preferably between 0.9 and 0.995. In an embodiment, the gas-containing vapor phase comprises a target gas and water vapor having a water vapor fraction of at least 0.9.

[0047] Here too, the water vapor content of the gas-containing vapor phase may be expressed as a water vapor / target gas ratio, where the water vapor / target gas ratio of the gas-containing vapor phase comprising the target gas and water vapor is preferably at least 4, more preferably at least 8, even more preferably at least 10. In an embodiment, the water vapor / target gas ratio is preferably between 4 and 1000.

[0048] In embodiments, the apparatus further comprises a heated lean trapping medium supply conduit for supplying heated lean trapping medium to at least one heating arrangement as a second thermal energy source for heating the target gas rich trapping medium. In these embodiments, the apparatus may be configured such that the first thermal energy source and the second thermal energy source provide the thermal energy necessary to heat the target gas rich trapping medium to a temperature that facilitates separation of the absorbed target gas from the trapping medium into a gas-containing gas phase comprising the target gas and water vapor. In embodiments, the supply of thermal energy to the heating arrangement is substantially provided, and preferably consists solely of, the heat recovered from the vapor recompression system in combination with the heat recovered from the heated lean trapping medium.

[0049] The process vessel includes any suitable process vessel in which the gas phase can be separated from the liquid phase. In an embodiment, the process vessel includes one of a flash vaporization vessel, a vaporization vessel, a boiling vessel, a desorption vessel, or a combination thereof.

[0050] The heating arrangement includes any suitable heat exchange vessel, system, or process that allows heat to be transferred from the feed-gas rich entrapment medium. If the process volume includes an entrapment medium, the at least one heating arrangement preferably includes a heating arrangement configured to heat the feed-gas rich entrapment medium in the process volume. The heating arrangement may include at least one heat exchanger. The heat exchanger may be at least one thermal (sensible) heat exchanger, a condensing heat exchanger, or at least one mixing heat exchanger. Here, the heat transfer may be through thermal heat exchange (sensible or latent heat exchange via conduction, convection, or radiation heat exchange). In latent heat exchange (phase change heat exchange), this is preferably through condensation heat. Alternatively, there may also be heat exchange through mixing.

[0051] In certain embodiments, the at least one heating arrangement comprises a reboiler, preferably a condensing reboiler, configured to heat the target gas rich entrapment medium therein, which is typically fluidly connected to a desorption vessel or column and used to heat the entrapment medium therein.

[0052] The target gas-rich trapping medium is not necessarily heated in the process volume. In embodiments, the gas-rich trapping medium may be preheated before entering the process volume of the process vessel. In these embodiments, the at least one heating arrangement includes at least one preheating arrangement configured to heat the feed gas-rich trapping medium before the feed gas-rich trapping medium is fed into the process volume. In some embodiments, at least the heated lean trapping medium is used to heat the target gas-rich trapping medium in the at least one preheating arrangement.

[0053] In some embodiments, the compressed steam is used to heat the target gas-rich trapping medium in at least one pre-heating arrangement. For example, in those embodiments, the process vessel includes a flash vaporization vessel and the compressed steam is used to heat the target gas-rich trapping medium in at least one pre-heating arrangement. In these embodiments, the heated lean trapping medium is typically also used to heat the target gas-rich trapping medium in at least one pre-heating arrangement.

[0054] As in the first embodiment, it should be understood that the vapor recompression system may be applied directly to the gas-containing gas phase formed in at least one heating arrangement as described above, and / or may also be used to compress a gas phase that is thermally associated with the gas-containing gas phase to form compressed vapor. In most processes, the vapor recompression system is applied directly to the gas-containing gas phase or a gas phase that is thermally associated with the gas-containing gas phase. However, it should also be understood that the process may include two parallel vapor recompression systems in which both the gas-containing gas phase or a gas phase that is thermally associated with the gas-containing gas phase undergo compression.

[0055] As described for the first aspect of the present invention, a secondary thermal working fluid may be used to heat the target gas-rich capture medium. In these embodiments, the secondary thermal working fluid is heated by a gas-containing gas phase. In an exemplary embodiment, the gas phase thermally associated with the gas-containing gas phase includes a water vapor gas phase. Here, the device may further include an indirect heat exchanger arrangement configured to use the gas-containing gas phase to heat the water-rich phase to generate said water vapor gas phase. The indirect heat exchanger may include any suitable heat exchange arrangement, such as at least one heat exchanger. The heat exchanger may be at least one thermal (sensible) heat exchanger, at least one condensing heat exchanger, or at least one mixing heat exchanger. Here, the heat transfer may be through thermal heat exchange (sensible or latent heat exchange via conduction, convection, or radiation heat exchange). In latent heat exchange (phase change heat exchange), this is preferably through heat of condensation. Alternatively, there may be heat exchange through mixing.

[0056] In an embodiment, the at least one heating arrangement comprises: A preheating arrangement including a condensing heat exchanger configured to transfer energy from compressed steam to heat the feed-gas rich entrapment medium before the feed-gas rich entrapment medium is fed into the process volume and the preheating arrangement.

[0057] The at least one heating arrangement may include two (or more) pre-heating arrangements. In an embodiment, the at least one heating arrangement comprises: a first pre-heating arrangement including a condensing heat exchanger configured to transfer energy from the compressed steam to heat the feed-gas rich entrapment medium before the feed-gas rich entrapment medium is fed into the process volume and the pre-heating arrangement; a second pre-heating arrangement configured to transfer thermal energy from the target gas and water phase after passing through the condensing heat exchanger to heat the feed-gas rich entrapment medium before it is fed into the process volume; Includes.

[0058] When the condensed target gas and aqueous phases include a content of entrapment medium, the apparatus may further comprise a separator configured to separate the entrapment medium from the target gas and aqueous phases to form a separated entrapment medium, hi some embodiments, the separated entrapment medium is mixed with the heated lean entrapment medium.

[0059] Again, the water vapor gas phase does not necessarily have to be used for heat exchange with the target gas-rich trapping medium in a reboiler or other heat exchange vessel. In an embodiment, compressed steam is used to heat the target gas-rich trapping medium by pumping the compressed steam into the target gas-rich trapping medium. In such an embodiment, the process vessel comprises a desorption vessel, and the at least one heating arrangement comprises at least one mixing heat exchanger configured to heat the target gas-rich trapping medium by pumping the compressed steam into the target gas-rich trapping medium in a process volume of the desorption vessel or a volume fluidly connected to said process volume. Here, the heat transfer is into the target gas-rich trapping medium through direct mixing of the heated medium. In an embodiment, the gas phase thermally associated with the gas-containing gas phase comprises a water vapor gas phase, which is pumped into the target gas-rich trapping medium in the process volume or a volume fluidly connected to the process volume of the desorption device, thereby directly heating the target gas-rich trapping medium.

[0060] The process vessel is preferably operated at atmospheric pressure or above atmospheric pressure, in an embodiment the process vessel has an operating pressure of at least 1 bara, preferably at least 1.5 bara.

[0061] The vapor recompression system can have any suitable configuration. In an embodiment, the vapor recompression system comprises multiple compressors arranged in series. In an embodiment, the vapor recompression system includes a single stage compressor or a multi-stage compressor. Each compressor preferably has a compression ratio between 1.1 and 10. In an embodiment where the vapor recompression system includes a multi-stage compressor, the apparatus further comprises at least one intercooler arranged between each compressor for recovering heat therefrom. The vapor recompression system and its compressors can be driven by any suitable power source or energy source. Preferably, the vapor recompression system is driven from a source of electrical power. The electrical power can have any source. However, renewable (green) energy sources (e.g., wind, solar, wave, etc.) can provide particularly advantageous efficiencies for the process of the present invention. Furthermore, renewable energy does not generate significant (if any) CO 2 No emissions are produced. As renewable energy such as electricity is increasingly being produced and is very accessible, it is also preferable to use only electricity to drive the heat regeneration.

[0062] In embodiments, the apparatus further comprises a condenser for condensing and recovering capture medium vapor from the compressed gas phase. In some embodiments, the apparatus further comprises a condenser for condensing and recovering water vapor from a gas phase thermally associated with the gas-containing gas phase. In some embodiments, the apparatus includes a separator configured to target gas from water from the gas-containing gas phase after passing through the at least one heating arrangement.

[0063] The apparatus of this third aspect of the invention may be fluidly connected to an absorber configured to absorb target gas from a feed gas stream into a capture medium to produce a target gas rich capture medium which is fed to a regenerator for regeneration of the capture medium and recovery of the absorbed target gas therefrom. This provides an overall target gas capture and recovery apparatus and process. In another embodiment, the invention provides an apparatus for removing target gas from a feed gas stream comprising an absorber fluidly upstream of a regenerator according to any one of the preceding claims. The feed gas stream is preferably a CO 2 , H 2 S, HCl, HF, SO 2 , S.O. 3 OR NO x a target gas selected from at least one of the following: 2 For example, the feed gas stream could be at least one of a flue gas from a combustion device for burning a carbonaceous fuel, such as a flue gas from a thermal power plant.

[0064] A fourth aspect of the invention provides a process according to the first aspect of the invention comprising pumping a gas-rich trapping medium through a regenerator according to the third aspect of the invention having a heating arrangement for heating the gas-rich trapping medium, thereby causing the trapped gas to dissociate into a gas-rich gas phase, wherein compressed steam is used to supply thermal energy to the heating arrangement.

[0065] The process and apparatus of the present invention captures CO from the direct air and from power plants. 2 The low CO resulting from the direct air capture process can be used for 2 At liquid loading, desorption conditions will be such that a high water vapor fraction occurs with typical regeneration temperatures between 100 and 120°C.

[0066] The high water vapor fraction allows the liquid sorbent to be deeply regenerated and 2This occurs when loads are limited in the absorption process, for example by operation at high liquid flow rates. The use of the present invention reduces CO2 emissions from coal or gas fired power plants as a result of the higher driving force of the absorber. 2 It may allow smaller absorber towers to be used in capture, which would result in smaller absorbers and CAPEX benefits.

[0067] Thus, a further aspect of the present invention provides a thermal power plant comprising combustion means for combusting a carbonaceous fuel and generating steam, the combustion means comprising combustion means for combusting a carbonaceous fuel and generating steam, and a regenerator according to the third aspect of the present invention. In some embodiments, the thermal power plant comprises a gas removal apparatus according to the third aspect of the present invention, and a flue gas outlet fluidly connected to supply flue gas directly from the combustor to the removal apparatus as a feed gas stream.

[0068] A preferred application of the process and apparatus of the present invention is the extraction of CO from ambient air. 2 capture (direct air capture - DAC) and liquid regeneration results in CO 2 This results in the production of high amounts of steam in the product. However, it should be understood that the present invention may be used in Liquid sorbent based CO 2 The capture process, in particular, 2 Water vapor / CO at the desorber outlet as a result of low loading 2 Direct air capture process with higher ratio. The process has higher circulating CO because the driving forces and reaction kinetics are more favorable. 2 Load or smaller CO 2 CO other than direct air capture can be used to achieve deep regeneration of the absorption liquid that may enable the absorber 2 Capture use. · Solid sorbent process, which uses steam to regenerate the sorbent. Conventional CO when deeper regeneration and leaner absorption liquids are required 2 Add-on to the capture process. This is2 There are advantages in terms of reducing the equipment size for the absorption process.

[0069] The present invention will now be described with reference to the accompanying drawing figures, which illustrate certain preferred embodiments of the invention. [Brief description of the drawings]

[0070] [Figure 1(a)] FIG. 1 illustrates an upstream target gas absorption process that can provide a target gas rich capture medium for the process of the present invention. [Figure 1(b)] FIG. 1 illustrates one process embodiment of the present invention illustrating absorbent regeneration using vapor compression of flashed gas (CO and water vapor) with subsequent heat transfer to a dense liquid. [Diagram 2] FIG. 1 illustrates an example process of the present invention illustrating absorbent regeneration using vapor compression of desorber off-gas (CO2 and water vapor) with subsequent heat transfer in a reboiler. [Diagram 3] FIG. 1 illustrates an example process of the present invention illustrating absorbent regeneration using vapor-compressed steam enhanced by heat exchange with desorber off-gas (CO and water vapor) with subsequent heat transfer to a reboiler. [Figure 4] FIG. 1 illustrates an example process of the present invention illustrating absorbent regeneration using vapor-compressed steam enhanced by heat exchange with desorber off-gas (CO2 and water vapor) with subsequent injection of water vapor into the desorber. [Figure 5A] FIG. 1 illustrates an example process of the present invention illustrating absorbent (MEA=monoethanolamine) regeneration using vapor compression of flash gas (CO and water vapor) with subsequent heat transfer to a dense liquid. [Figure 5B] FIG. 1 illustrates an example process of the present invention illustrating absorbent (glycinate) regeneration using vapor compression of flash gas (CO and water vapor) with subsequent heat transfer to a dense liquid. [Figure 6A]FIG. 1 illustrates an example process of the present invention illustrating the process flow diagram and conditions for absorbent regeneration using vapor compression of water vapor enhanced by heat exchange with desorber off-gas (CO2 and water vapor) with subsequent injection of water vapor into the desorber (lean loading = 0.02). [Figure 6B] FIG. 1 illustrates an example process of the present invention illustrating the process flow diagram and conditions for absorbent regeneration using vapor compression of water vapor enhanced by heat exchange with desorber off-gas (CO2 and water vapor) with subsequent injection of water vapor into the desorber (lean loading=0.014). [Figure 6C] FIG. 1 illustrates an example process of the present invention illustrating the process flow diagram and conditions for absorbent regeneration using vapor compression of water vapor enhanced by heat exchange with desorber off-gas (CO2 and water vapor) with subsequent injection of water vapor into the desorber (lean loading=0.006). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0071] The present invention is 2 The present invention provides a process, apparatus and system for the regeneration of a capture medium, such as a liquid absorbent, used to capture a target such as a target gas, where the thermal energy required for the regeneration process is provided by thermal energy in a desorption process, more particularly a vapor compression process. The present invention typically forms part of a target gas absorption-desorption process that includes an absorber 100, as illustrated in FIG. 1(a), coupled with a vapor separator vessel such as a flash vessel 200 (FIG. 1(b)) or a desorber / regeneration vessel 200, 200A, 200B (FIGS. 2, 3 and 4).

[0072] The following discussion concerns the capture of carbon dioxide. However, the H that can be absorbed by a suitably matched absorption fluid / liquid is not. 2 S, HCl, HF, SO 2 , S.O. 3 , or NO x It should be understood that other target gases such as can equally be used.

[0073] FIG. 1(a) illustrates a conventional absorption tower system 100, in which a target gas (CO 2 A gas stream containing lean absorbent -- i.e., CO 2 The absorbent stripped against CO is introduced into the upper section of the absorber 100 through lean absorbent line 120. Gas flows from the bottom to the top of the absorber 110 in the opposite direction to the lean absorbent flowing from the top to the bottom of the absorber 110. The lean gas, i.e., CO 2 The exhaust gas from which a substantial portion of the CO has been removed is removed through a gas outlet line 130 at the top of the absorber tower 110, but without the fat absorbent, i.e., CO 2 The absorbent, which has already absorbed , exits the absorber tower 110 through fat absorbent line 140.

[0074] CO from gas streams 2 Regeneration of the aqueous absorbing liquid used in an absorption system such as that shown in Figure 1(a) applied to the capture of acid gases such as CO can be achieved without the need for CO2 capture as a result of the thermoreversible nature of the capture process. 2 When CO is released or desorbed from an aqueous solution, it is usually done at high temperatures (90 to 150 °C). This is accomplished through the supply of heat at the required temperature level from a suitable heat source such as a power plant, a separate boiler, a solar thermal process, a geothermal process, or a water steam cycle of any other heat source. The supply of heat typically results in the production of CO 2 This results in additional emissions of CO2, which needs to be considered in the overall emission reductions. In some situations, the heat source is not available and heat needs to be generated in a separate facility, resulting in 2 Emissions will increase significantly.

[0075] One type of regeneration system is shown in Figures 2 and 3 and includes a desorber vessel / column 310. Fat absorbent 140 from absorber tower 100 is heated in heat exchanger 312 (Figure 1(a)) to a temperature typically in the range of 90 to 110°C relative to the lean absorbent returned to the absorber tower before the fat absorbent is introduced into desorber column 310 via inlet conduit 340. In desorber column 310, the fat absorbent flows downwardly countercurrent to steam generated by heating a portion of the absorbent in desorber reboiler 315. Lean absorbent exits desorber column 310 through lean absorbent outlet 316. A portion of the lean absorbent in outlet 316 is introduced into desorber reboiler 315 via line 317 where it is heated to a temperature typically in the range of 120 to 130°C to produce hot absorbent and steam that is reintroduced into desorber column 310 via line 318. Heating from the bottom of the desorber column 310 provides a temperature gradient from the bottom to the top of the column 310 at steady state, with the temperature at the top being on the order of 10 to 50° C. lower than at the bottom, depending on the actual design of the column 310. The pressure within the desorber column 310 determines the effective desorption of the absorbent or CO 2 The pressure in the desorber column 310 is usually at or above atmospheric pressure so as to obtain a stripping of 1.5 bara. The pressure in the desorber column 310 is often at or above 1.5 bara. In practical situations, the pressure is often about 1.5 to about 2.0 bara, but can even exceed this pressure.

[0076] Lean absorbent in line 316 that is not introduced into the desorber reboiler 315 is recycled back to the absorption column 110 (FIG. 1(a)) via line 320 and cooled in heat exchanger 312 against the fat absorbent in line 140. In heat exchanger 315, the relatively cool fat absorbent is heated against the relatively hot lean absorbent exiting the absorber 110 at a temperature of about 120° C. Depending on the actual size and configuration of the power plant, the temperature of the absorbent exiting heat exchanger 312 for the absorber 110 may be from about 90 to about 110° C.

[0077] CO released from the absorbent 2The water vapor, water and small amounts of absorbent form a gas-containing vapor phase that is removed from desorber column 310 through gas removal line 350. It should be understood that the water vapor removed through line 350 and the condensed water removed in desorber column 310 may contain small amounts of absorbent. Thus, the water and water vapor from line 350 will typically contain water and water vapor, with small amounts of absorbent, if appropriate. Treatment of the gas-containing vapor phase from gas removal line 350 depends on the particular embodiment of the invention, as described below.

[0078] In conventional regenerative systems, the lean absorbent in the reboiler 315 is typically heated using a heating medium such as electricity or steam. Generally, providing heat energy via electricity, for example using resistive or inductive heating, is considered wasteful and electrically powered heat pumps are preferred as they are more efficient. In such heat pump applications, the gas is compressed, resulting in a temperature increase due to heat recovery via condensation of a liquid from the compressed gas.

[0079] The present invention relates to the regeneration of aqueous absorption liquid and CO 2 They propose the use of a vapor compression system to more efficiently recover the heat energy required for desorption from the system. Two systems are proposed: (1) Direct vapor compression systems (Figures 1(b) and 2), and (2) Indirect vapor compression system (Figures 3 and 4).

[0080] The starting point for both direct and indirect vapor compression systems is the amount of CO released. 2 The amount of heat energy required per unit mass, so-called specific reboiler duty (MJ / kg CO 2 The thermal energy requirement has three contributions: 1) CO as determined by the chemical formula 2 The energy required to break the bonds between the active ingredient in the absorbing liquid and the 2) The CO in the absorption liquid required to raise the solvent to the regeneration temperature 2 Load and CO 2 Heat, which is a function of the temperature difference between the desorbers. 3) CO 2 Together with CO 2 CO at the top versus water vapor exiting the desorber 2 Water vapor saturated CO leaving the desorber 2 The enthalpy of deposition is determined by the temperature of the product.

[0081] The minimization of the amount of required heat energy is based on its intrinsic properties, such as vapor-liquid equilibrium and reaction enthalpy, as well as the CO 2 CO with extensive evaluation of different absorption liquids, taking into account process conditions such as regeneration temperature and pressure in the desorber 2 This is an important objective in the development of capture technology. 2 The amount of water vapor leaving the desorber represents an energy loss, so process and design optimization requires a reduction in CO 2 Water vapor / CO in the stream exiting the desorber 2 The applicant's U.S. Patent No. 10,040,023, "Process and apparatus for heat integrated liquid absorbent regeneration through gas desorption," is one example of how the amount of heat energy required can be minimized through new process and equipment designs.

[0082] As explained in the Background section, CO 2 CO from the desorber to reduce the amount of heat energy required for desorption. 2 A number of prior art processes have been developed that use CO2 compression with subsequent heat recovery. However, none of these processes require all of the heat energy required, which is provided by energy transfer from a regeneration / desorption step within the process. 2 It does not include a desorption process. This means that the concept of an energy-efficient liquid regeneration process is CO 2Wet CO leaving the desorber 2 Such processes do not realize the full benefits of the vapor compression process because they are based on minimizing the moisture content of the product.

[0083] In the present invention, the CO 2 The water vapor content in the product is high (within the range of water vapor fractions described below) to achieve high energy recovery via condensation of water to supply the overall heat requirement of the capture process. This is in contrast to the CO2 capture in prior art regeneration processes. 2 This is in contrast to the common approach, which involves minimizing the water vapor content in the outlet stream from the desorber.

[0084] As mentioned above, CO 2 The latent heat contained in the exit gas stream from the desorber is used to regenerate the absorbing liquid and to generate CO 2 It can be recovered during desorption and reused. 1. Water vapor / CO 2 Condensate from the stream is used directly (eg, the systems illustrated in Figures 1(b) and 2). 2. Indirect use for steam generation via heat recovery of the condensate (eg, the systems illustrated in Figures 3 and 4).

[0085] Direct latent heat recovery In addition to exchanging heat between the lean and rich liquid streams (e.g., as shown using heat exchanger 312 in FIG. 1(a)), the direct system also uses CO 2 Desorption of water vapor and CO with subsequent heat recovery to an extent sufficient to provide the total additional thermal energy required for the desorption process. 2 CO 2 Compression of the exit gas stream from the desorber vessel is required. As such, CO 2 The capture process can be operated using only electrical energy, which can be sourced from renewable sources such as solar cells or wind turbines. Broadly speaking, two routes for heat recovery have been identified by the inventors.

[0086] Concept 1: As illustrated in FIG. 1(b), the system 200 includes an influent dense liquid absorbent 240 fed into a flash vessel 210, and a CO 2 and water vapor (line 250) to separate the lean liquid (line 220) through flash vaporization. After flashing, the CO 2 The steam / water vapor mixture is compressed and heat recovery occurs from the compressed vapor stream in condenser 215 via condensation of water. Heat is transferred to inlet rich liquid absorbent 240 in condenser 215 to produce further heated rich liquid absorbent 240A. The pressure in flash vessel 210 is adjusted to effectively desorb the absorbent or CO 2 Typically, the pressure is at or above atmospheric pressure, more typically at or above 1.5 bar, so as to obtain a stripping of 1.5 bar. In practice, the pressure is often about 1.5 to about 2.0 bar, but can even exceed this pressure.

[0087] This initial concept is similar to the mechanical vapor recompression (MVR) process, where low applied pressure and high deposition rates are used. MVR is used in industrial applications such as the production of fresh water from seawater and the dehydration of liquids and solids.

[0088] Concept 2: This concept (system 300A) includes the previously described desorber column 310 and desorber reboiler 315, which processes the gas-containing vapor phase removed from the desorber column 310 through gas removal line 350. As illustrated in FIG. 2, the CO 2 The water / steam mixture is compressed in compressor 360 and the resulting compressed steam (in line 370) is then fed into reboiler 315 where heat is recovered from the compressed steam stream via condensation of water and transferred / heated to the recirculating lean absorbent liquid at the bottom of desorber column 310, thereby reducing the CO 2This is similar to the steam stripping process in a standard desorber column where water vapor is generated at the bottom of the desorber column 310.

[0089] Steam / CO 2 Compression of the flow is 2 When used for geological storage, high pressure CO, e.g., pressures above 100 bar, 2 Such high pressures are advantageous over most subsequent storage and utilization options, which often require high CO 2 is used as a reactant to produce carbonates or fuels, or CO 2 is not necessary when used to promote plant growth.

[0090] Indirect latent heat recovery The indirect process is via condensation of CO 2 It is based on transferring the latent heat in the outlet gas stream from the desorber to the inlet water stream which is converted to water vapor. The latent heat from the high water vapor fraction in the desorber outlet can thus be converted to pure water vapor which is then compressed with heat recovery via condensation by the following route:

[0091] Concept 3: This concept (system 300B) also includes the previously described desorber column 310 and desorber reboiler 315 to process the gas-containing vapor phase removed from the desorber column 310 through gas removal line 350. As illustrated in FIG. 3, the CO 2 The CO / water vapor mixture is taken from the gas withdrawal line 350. 2 The CO / water vapor mixture enters heat exchanger 440, which transfers the latent heat of the mixture to water in line 442, producing a water vapor / water vapor phase that exits heat exchanger 440 in line 450. 2 The wet CO / water vapor mixture 2The water vapor phase in line 450 is compressed in compressor 460 and pumped to reboiler 315 via line 462. Heat transfer to the absorbing liquid in desorber column 310 is via condensation of the water vapor and latent heat transfer in reboiler 315 and / or via a preheat arrangement (not illustrated) to the incoming rich solution in line 340. The condensate is discharged from the system in line 470 and can be recycled back to heat exchanger 440 via line 442 to generate additional water vapor. This facilitates a completely closed vapor compression based water vapor cycle for heat recovery from and supply to desorber column 310. The closed system can be based on other working fluids--heat transfer fluids--than water.

[0092] Concept 4: As illustrated in FIG. 3, the system 300C receives CO from a gas withdrawal line 350. 2 The CO from the gas withdrawal line 350 of the desorber column 310 enters into a heat exchanger 440 which transfers the latent heat of the water / steam mixture to the water in line 442 to produce a water vapor / steam phase which exits the heat exchanger 440 in line 450. 2 CO / water vapor mixture. 2 The wet CO / water vapor mixture is then mixed with the wet CO in line 474. 2 The steam exits the heat exchanger in line 473 as a water vapor phase and water / condensate (see, e.g., FIG. 6A). The steam phase in line 450 is then compressed and fed directly into the desorber column 310. The injection of steam into the desorber column 310 replaces the reboiler as a heat supply and reduces the amount of CO 2 This embodiment does not require any additional heat exchange equipment. The input water stream can be supplemented by condensate from the desorber column 310, and the resulting water vapor acts as stripping gas in the desorber column 310.

[0093] The process operation in both direct and indirect processes is 2It is most beneficial when the product water vapor content is high, as this results in the highest recovery of latent heat from that stream fraction. In this regard, each of the processes illustrated in Figures 1(b) through 4 operate with the following operating parameters: CO 2 Water vapor / CO in the outlet stream of the desorber 2 The ratio needs to be high to allow significant recovery of latent heat in addition to recovery of sensible heat, which requires a water vapor fraction of at least 0.8, and preferably higher than 0.9.

[0094] A variety of liquid absorbing agents may be used. Preferred absorbing liquids are: Salt solutions, i.e. solutions without vapor pressure, such as alkaline salt solutions or amino acid salt solutions. Illustrative examples include potassium, lithium and sodium salts of carbonate, phosphate, glycine, taurine, alanine, sarcosine, proline, lysine, methyltaurine, methionine, aminohexanoic acid, phenylalanine, glutamic acid, arginine aspartic acid, leucine, serine, threonine, glucosamine, dimethylglycine, methylaminopropionic acid, aminobutyric acid, pipecolic acid, preferably with a concentration between 0.005 and 5.0 M, more preferably between 0.5 and 2.5 M. It should be understood that various other absorbents may be used, such as those taught in Australian Patent No. AU552657B2, entitled "amino-acids for gas absorption," U.S. Patent No. US 2,176,441, entitled "Removal of gaseous weak acid from gases containing the same," and Canadian Patent No. CA619,193, entitled "Process for separating carbon dioxide from gas mixtures," the contents of which are understood to be incorporated herein by reference. CO 2 CO determined at the desorber outlet 2Amine solutions with amine vapor pressures that are less than 10% of the partial process would be acceptable for use.

[0095] Further optimization for different absorption liquids and under various process conditions involves a trade-off between power consumption for compression and lean load requirements. Low lean loads reduce CO 2 This is beneficial for the absorption process, resulting in higher mass transfer and therefore smaller equipment, however this is accompanied by a deeper degree of absorbent regeneration and therefore an increase in the specific power consumption.

[0096] The presence of amine vapors results in CO 2 This leads to co-absorption of CO and amines in the condensate, resulting in the formation of CO due to reactions with the amines. 2 Partial removal of CO occurs. 2 This loss is acceptable if it is small compared to the pressure, for example 10%.

[0097] The compression arrangement in the systems shown in Figures 1(a) to 4 can be single or multi-stage, with heat being recovered from an intercooler between each stage. Typical compression ratios are in the range of 1.1 to 10 for each stage. As explained previously, the compression ratio is determined by the ratio of water vapor / CO in the exit stream. 2 Ratio and CO 2 It depends on the requirements due to the use of the product. Within the range of 0.8 to 0.999 water vapor fraction in the outlet stream, higher compression ratios generate more sensible heat and are most effective in the lower zone range, while lower compression ratios are most effective in the higher zone range. These considerations are important in determining the CO 2 However, this may be overruled by the need to supply water vapor / CO at high pressure. 2 A high compression ratio is desirable regardless of the ratio. This is because 2 is sent for transport as a supercritical fluid to a geological repository.

[0098] It should be understood that the concept described above may also include additional process steps or stages. For example, the target gas and water / water vapor phase from line 250 (FIG. 1(b)) and line 350 (FIGS. 2, 3, and 4) may include a small amount of absorbent. After being condensed (i.e., passing through the heat exchanger / condenser 215, 315, 440), the process may further include a separator (e.g., separator 280 in FIG. 5A or separator 380 in FIG. 5B) configured to separate the absorbent from the target gas and water / water vapor. The separated absorbent may be mixed back into the lean liquid recycled back to the absorption column 110 (FIG. 1(a)). It is noted that this additional stage may involve a deeper degree of absorbent regeneration and thus an increase in the specific power consumption.

[0099] (Example) The following examples were developed using process models developed in the ProTreat® simulator, a process simulator tool for gas treatment available from Optimized Gas Treating, Inc. (OGT), Budapest, Texas.

[0100] Example 1 Concept 1 An example of a sorbent regeneration system based on Concept 1 (FIG. 1(b)) is presented in FIG. 5A for a process using an aqueous 2 M monoethanolamine (MEA) solution. The same reference numbers are used in FIG. 5A for similar features as used in FIG. 1(a) and FIG. 1(b).

[0101] A process model was developed in ProTreat® as described above based on the process flow diagram presented in Figure 5A. In this model, dense liquid 140 coming from absorber 110 is converted from air to CO 2 When capturing 0.3 mol / mol of CO 2It was determined that the rich liquid 140 had a load of 1.5 bar. The rich liquid 140 was heated in two heat exchangers 312 and 215 and then sent to the flash vessel 210 where the vapor was released in vapor stream 250 at 1.5 bar. The vapor stream 250, having a water vapor fraction of 0.99, was then compressed to 3 bar in the compressor 260 raising the temperature of the vapor mixture to 208°C. The vapor was partially condensed in the condenser / heat exchanger 215 and heat was transferred to the incoming rich absorbent liquid. The condensed vapor stream was converted to CO 2 The resulting mixture enters separator 280 which separates hot / water (line 275A) and any absorbent liquid (line 275B). The absorbent liquid is mixed into hot lean liquid 220 through mixer 282 to form mixed hot lean liquid 220A. After flashing, the lean liquid exits flash vessel 210 with a dilute loading of 0.056 mol / mol, passes through heat exchanger 312, transfers heat to inlet rich liquid 140, and is then recycled back to the absorber to convert CO2 from the atmosphere into a mixed hot lean liquid 220A. 2 is used to capture

[0102] The specific power consumption of vapor compression (efficiency = 0.8) is 1.94 MWh / tonne CO 2 is equal to.

[0103] Example 2 Concept 1 A second example of the process of Concept 1 (FIG. 1(b)) is shown in FIG. 5B. Again, the same reference numbers are used in FIG. 5A for similar features as used in FIG. 1(a) and FIG. 1(b). As with the first example, the process was modeled in ProTreat® for an amino acid salt solution (2M sodium glycinate) based on the process flow diagram shown in FIG. 5B.

[0104] In this example, H of the vapor stream from the flash operation was measured under process conditions similar to those described above for Example 1. 2The O vapor fraction was lower (0.835) with a lower compression ratio (from 1.5 bar to 2.2 bar) and a lower degree of regeneration (lean liquid loading = 0.088 mol / mol) was achieved. In addition, an additional heat exchanger 313 was included that transfers latent heat from the condensed vapor stream 275 to the rich solution 140 from the absorber 110 (FIG. 1(a)). The vapor stream 275A is a CO 2 284 to separate the amino acids and water.

[0105] The overall process results in 1.12 MWh / tonne CO 2 A low compression energy requirement was obtained.

[0106] Further optimization for different absorption liquids and under various process conditions may involve a trade-off between power consumption for compression and lean load requirements. Low lean loads reduce CO 2 This is beneficial for the absorption process, resulting in higher mass transfer and therefore smaller equipment, however this is accompanied by a deeper degree of absorbent regeneration and therefore an increase in the specific power consumption.

[0107] Example 3 A process modeling example is provided in which the exhaust from the desorber is compressed to 10 bar via a two-stage adiabatic compression process according to the process illustrated in Figure 2. This pressure level is reached by 2 CO reacts with hydrogen to produce methane in the methanation process. 2 is suitable for supplying

[0108] The compression process in the process in Figure 2 was modeled by estimating the heat generated from the compression process by cooling the compressed vapor to 135 °C and comparing this to an estimate of the reboiler duty. The reboiler duty represents the reaction enthalpy in the relevant range of CO 2 The heat associated with the absorption process was estimated for three cases. Then, CO 2To this was added the heat for the generation of water vapor present with the compressor. In the modelling, two desorber exhaust temperatures, 100°C and 120°C, at two different pressure levels were considered, the temperature of the compressed steam was reduced to 135°C at the end of each stage and heat was transferred in the reboiler as a result of water condensation. Various water vapor fractions were considered and the process simulation results (specific power consumption of the compressor and specific heat recovery from the compressor) are shown in Table 1.

[0109] Table 1 shows where the heat from the compression process exceeded the reboiler heat requirement and is therefore not used to provide a single case result, but rather to provide a range of minimum steam ratios. The amount of heat required to heat the absorption liquid in the desorber was assumed to be negligible. Referring to Table 1, it can be seen that the higher the steam ratio, the higher the specific compressor power consumption, but also the amount of heat that can be recovered. At a higher inlet temperature of 120°C and a higher outlet pressure of 2 bar, the specific power consumption is lower than the 100°C / 1 bar case. The amount of heat recovery is slightly lower.

[0110] [Table 1]

[0111] [Table 2]

[0112] Table 1 also shows the specific energy required for the regeneration of the absorption liquid, the so-called reboiler duty. In the calculations, the regeneration energy is calculated as 2It is calculated as the sum of the required reaction enthalpy for desorption and the latent heat of deposition for water. In this relatively simple analysis, the amount of heat required to heat the absorption liquid after heat exchange with the regenerated solution is neglected, assuming an ideal temperature approach for the heat exchange. The reboiler duty calculated in this way is the minimum and is calculated for three values ​​of reaction enthalpy for chemical absorption that cover a range of values ​​for chemical absorption liquid: 50, 75, and 100 kJ / mol CO 2 For water evaporation, it is 37.5 kJ / mol H for the temperature range 100 to 120 °C. 2 The average value of O was used. The reboiler duty increases with increasing reaction enthalpy for the selected chemical absorbent.

[0113] From Table 1, it can be seen that for water vapor fractions equal to or less than 0.8, the compressor is not able to provide enough energy for the regeneration of the absorbing liquid. For water vapor fractions equal to or greater than 0.9, sufficient heat is available for the regeneration of the absorbing liquid. For higher water vapor fractions, the overall compression energy requirement increases, and the optimum condition is when the water vapor content is high enough to provide heat to the reboiler via the vapor compression process, but not higher, as this would unnecessarily increase the energy requirement. The water vapor content is determined by the properties of the absorbing liquid and is the ratio of the CO 2 It depends on the load and temperature. In the example of compressing to 10 bar, the "break-even" water vapor fraction is shown to be between 0.8 and 0.9. This "break-even" point also depends on the compression ratio of the vapor compression process. In another example, the pressure ratio for vapor compression is varied between 1.25 and 10, assuming a single stage compression process and assuming vapor leaving the desorber at 100°C / 1 bar. In order to understand the trend and potential of heat recovery, a 100% compressor efficiency was used in this calculation and it was assumed that all latent heat could be recovered.

[0114] Table 2 shows the results for four compression ratios (1.25, 2.5, 5, 10) and CO 2The results of the specific heat recovery (H) and the specific compressor power consumption (P) are shown for a range of water vapor fractions (0.5 to 0.999) in the outlet steam from the desorber. The results also show the CO 2 The estimated minimum specific reboiler duty of the desorption process is also presented. These reboiler duties can be compared with the heat recovery from the compression process (H). The values ​​where the heat from the compression process exceeds the reboiler duty for all values ​​of reboiler duty are shown in bold for clarity. At low compression ratios, the water vapor fraction needs to be high to achieve a sufficiently high heat recovery from the compression process, e.g., at a pressure of 1.25 bar after compression, the water vapor fraction needs to be at least 0.99 to 0.995 to achieve. At a pressure of 10 bar after compression, the water vapor fraction can be somewhat lower, i.e., above 0.8 to 0.9, to achieve break-even. A high water vapor fraction leads to a sharp rise in the specific power consumption as shown in Table 2. This requires a comparison of the specific absorption liquid, CO, and CO2 ratios to determine the optimal compression conditions that minimize the compression power consumption and achieve sufficient heat recovery from the compression process. 2 This indicates that careful optimization of loading and regeneration process design is required.

[0115] A simplified analysis shows here that for the relevant pressure conditions of 1.25 to 10 bar, the water vapor fraction needs to be in the range of 0.8 to 0.995 to achieve a situation where the heat covered by the compression process is sufficient to supply the reboiler load. At lower steam fractions, the heat generated by compression is insufficient to fully cover the reboiler load. At higher steam fractions, the CO 2 Since large amounts of water vapor need to be processed, the equipment can become quite large and expensive, and the power consumption of the compressor increases rapidly, which is undesirable.

[0116] Example 4 Concept 4 The process configuration shown in FIG. 4 was modeled in Protreat® for a variety of conditions of different regeneration degrees using 2 M sodium glycinate as a representative amino acid salt solution.

[0117] The absorption liquid entering the regeneration system absorbs CO from the air. 2 The desorber had a liquid loading equivalent to 0.3 mol / mol that can be achieved through capture. The desorber was operated at a pressure of 150 kPa (1.5 bar) under isothermal conditions (~112°C) for all process simulations. The water vapor compressor was assumed to have an efficiency of 80%. The rich liquid 140 was preheated in heat exchanger 312 using hot lean liquid exiting the bottom of the desorber column 310. The heated rich liquid is then pumped into the desorber column 310.

[0118] The resulting process diagrams are shown in Figures 6A, 6B, and 6C for lean loads equal to 0.02, 0.014, and 0.006. The diagrams show the conditions that were modeled. The results are also summarized in Table 3. Note that the same reference numbers are used in Figures 6A, 6B, and 6C for similar features as used in Figures 1(a) and 4.

[0119] [Table 3]

[0120] Example 5 Concept 3 The process configuration shown in FIG. 3 was modeled in Protreat® for a variety of conditions of different regeneration degrees using 2 M sodium glycinate as a representative amino acid salt solution.

[0121] The dense absorption liquid 340 (α=0.3, 14420 kg / hr) entering the regeneration system at a temperature of 104.5°C absorbs CO from the air. 2The desorber 310 was operated at a pressure of 150 kPa (1.5 bar) and a bottom temperature of 115° C., with the regenerated lean absorbent liquid 320 finishing regeneration at a temperature of 112.2° C. (α=0.036, 14120 kg / hr) and having a liquid loading equivalent to 0.036 mol / mol.

[0122] The vapor mixture leaving the desorber 350 exchanges heat with influent water stream 442 (@40° C., 8150 kg / hr), resulting in the production of steam 450 at a temperature of 110° C. and a pressure of 150 kPa (8150 kg / hr). 2 and the condensate is discharged in a stream 475 at 45°C and a pressure of 150 kPa (CO 2 This steam is compressed to 290 kPa (8150 kg / hr) using compressor 460, resulting in an adiabatic compression resulting in an outlet temperature of 195° C. in line 462, and is condensed in reboiler 315 to condensate 470 at a temperature of 132.5° C., transferring heat to the absorption liquid which leaves the reboiler in stream 318. The steam compressor is assumed to be 80% efficient, and the power consumption of the process is 1.2 MWh / tonne CO 2 is equal to.

[0123] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described, and it is understood that the invention includes all such variations and modifications that fall within the spirit and scope of the invention.

[0124] The words "comprise", "comprises", "comprised" and "comprising", when used in this specification (including the claims), should be interpreted as specifying the presence of stated features, integers, steps or components but not excluding the presence of one or more other features, integers, steps, components or groups thereof. [Explanation of symbols]

[0125] 100 Absorbent 110 Absorption vessel, absorption tower 112 Gas inlet line 120 Lean absorbent line 130 Gas Outlet Line 140 Thick Absorbent Line 200 Flash Vessel 200A, 200B Desorption device / regeneration vessel 210 Flash Container 215 Condenser 220 line, hot dilute liquid 220A Mixed high temperature dilute liquid 240 Inflow thick liquid absorbent 240A More heated dense liquid absorbent 250 Line 260 Compressor 275 Steam Flow 275A Line 275B Line 280 Separator 282 Mixer 284 Separator 300A System 300B System 310 Desorption device container, desorption device column 312 Heat exchanger 313 Heat exchanger 315 Desorber Reboiler 316 Lean absorbent outlet 320 Line 340 Inlet conduit 350 Gas Extraction Line 360 Compressor 370 Line 380 Separator 440 Heat exchanger 442 Line 450 Line 460 Compressor 462 Line 470 Line 473 Line

Claims

1. A process for regenerating a trapping medium rich in a trapped target gas, comprising: using thermal energy to heat a target gas rich trapping medium comprising an absorbent medium, an absorbed target gas, and water, thereby facilitating separation of the absorbed target gas from the trapping medium into a gas-containing vapor phase and a heated lean trapping medium, the gas-containing vapor phase comprising the target gas and water vapor having a water vapor fraction of at least 0.8; compressing at least one of the gas-containing vapor phase or a vapor phase thermally associated with the gas-containing vapor phase to form a compressed vapor; heating the target gas rich entrapment medium using the compressed steam as a thermal energy source; The process includes:

2. 2. The process of claim 1, wherein the gas-containing vapor phase comprises the target gas and water vapor having a water vapor fraction between 0.8 and 0.999, preferably a water vapor fraction of at least 0.

9.

3. 3. The process of claim 1 or 2, wherein the step of separating the absorbed target gas from the capture medium into a gas-containing vapor phase comprises one of flash vaporization, vaporization, boiling, stripping, or a combination thereof.

4. 4. The process of claim 1, wherein the step of separating the absorbed target gas from the capture medium into a gas-containing vapor phase is carried out in one of a flash vessel or a desorption vessel.

5. 5. The process of claim 4, wherein the desorption vessel includes a reboiler, and at least the compressed steam is used to heat the target gas rich entrapment medium in the reboiler.

6. The vapor phase in thermal association with the gas-containing vapor phase comprises a heat transfer fluid, and the process comprises:

6. The process of claim 1, further comprising the step of heating a heat transfer fluid using the gas-containing vapor phase to produce a heated heat transfer fluid.

7. The heat transfer fluid comprises a water dense phase, and the process comprises: heating the water-rich phase using the gas-containing vapor phase to produce a water vapor phase.

7. The process of claim 6, further comprising:

8. The water-rich phase is Heat exchange with the gas-containing vapor phase 8. The process of claim 7, wherein the heating is performed using

9. The compressed steam is in thermal exchange with the target gas rich entrapment medium; or Condensation heat exchange with the target gas-rich trapping medium 9. The process of claim 1 , further comprising the steps of: generating a condensed target gas and a water phase which is then used to heat the target gas rich capture medium.

10. 10. The process of claim 9, further comprising using the condensed target gas and aqueous phase as an additional thermal energy source for heating the target gas rich entrapment medium.

11. 11. The process of claim 9 or 10, wherein the condensed target gas and aqueous phase composition comprises a certain content of entrapment medium, the process further comprising a step of separating the entrapment medium from the target gas and aqueous phase to form a separated entrapment medium.

12. 12. The process of claim 11, wherein the separated entrapment medium is mixed with the heated lean entrapment medium.

13. 13. The process of claim 1, wherein the gas phase thermally associated with the gas-containing gas phase comprises a water vapor phase, the water vapor phase being pumped into the target gas rich trapping medium, thereby directly heating the target gas rich trapping medium.

14. The heated lean trapping medium is Heat exchange with the target gas rich trapping medium The process of claim 1 , wherein a heating agent is used to heat the target gas rich trapping medium.

15. 15. The process of claim 1, wherein the compression step comprises a single compression stage or multiple compression stages.

16. 16. The process of claim 1, wherein the compression step comprises multiple compression stages in which heat is recovered from at least one intercooler disposed between each compression stage.

17. 17. The process of claim 16, wherein each compression stage has a compression ratio between 1.1 and 10.

18. The target gas is CO 2 , H 2 S, HCl, HF, SO 2 , S.O. 3 , or NO x At least one of the following, preferably CO 2 18. The process according to any one of claims 1 to 17, comprising:

19. The absorbent medium comprises: a salt solution, preferably an alkaline salt solution or an amino acid salt solution, or CO in the gas-rich capture medium 2 Amine solutions with amine vapor pressures that are less than 10% of the partial pressure 19. The process according to any one of claims 1 to 18, comprising at least one of:

20. 20. The process of claim 1, wherein the compressed steam is used as a first thermal energy source to provide the thermal energy required to heat the target gas rich trapping medium, and the heated lean trapping medium is used as a second thermal energy source to provide the thermal energy required to heat the target gas rich trapping medium.

21. 1. A process for removing and recovering a target gas from a gas stream, comprising: absorbing a target gas from a feed gas stream into a trapping medium by passing the feed gas stream through a lean trapping medium to cause a target gas component of the gas stream to be absorbed into the trapping medium to produce a target gas rich trapping medium; Treating the target gas rich entrapment medium according to a process according to any one of claims 1 to 20; The process includes:

22. 1. An apparatus for regenerating a trapping medium enriched with a trapped target gas and recovering the trapped gas therefrom, comprising: a process vessel including a process volume; a supply conduit for delivering a gas rich entrapment medium into the process volume; at least one heating arrangement configured to heat the gas-rich trapping medium to a temperature that facilitates separation of the absorbed target gas from the trapping medium into a gas-containing gas phase comprising the target gas and water vapor having a water vapor fraction of at least 0.8 to produce a heated lean trapping medium; a vapor recompression system fluidly connected to the process volume, the vapor recompression system receiving and compressing a gas-containing vapor phase from at least one of the process volume or a vapor phase thermally associated with the gas-containing vapor phase to form a compressed vapor; a compressed steam supply conduit for supplying compressed steam to the at least one heating arrangement as a thermal energy source for heating the gas-rich trapping medium; An apparatus comprising:

23. 23. The apparatus of claim 22, further comprising a heated lean trapping medium supply conduit for supplying heated lean trapping medium to the at least one heating arrangement as a second thermal energy source for heating the gas-rich trapping medium.

24. 24. Apparatus according to claim 22 or 23, wherein the gas-containing gas phase comprises the target gas and water vapour having a water vapour fraction between 0.8 and 0.999, preferably a water vapour fraction of at least 0.

9.

25. 25. The apparatus of any one of claims 22 to 24, wherein the process vessel comprises one of a flash vaporization vessel, a vaporization vessel, a boiling vessel, a desorption vessel, or a combination thereof.

26. 26. Apparatus according to any one of claims 22 to 25, wherein the at least one heating arrangement comprises a heating arrangement configured to heat the gas-rich entrapment medium in the process volume into which it is fed.

27. 24. Apparatus according to claim 22 or 23, wherein the at least one heating arrangement comprises at least one heat exchanger, a condensing heat exchanger or at least one mixing heat exchanger.

28. 28. Apparatus according to any one of claims 22 to 27, wherein the at least one heating arrangement comprises a reboiler, preferably a condensing reboiler, configured to heat the gas-rich entrapment medium therein.

29. 29. The apparatus of claim 22, wherein the at least one heating arrangement comprises at least one pre-heating arrangement configured to heat the gas-rich trapping medium before it is fed into the process volume.

30. 30. The apparatus of claim 29, wherein at least the heated lean trapping medium is used to heat the gas rich trapping medium in the at least one preheating arrangement.

31. 31. The apparatus of any one of claims 22 to 30, wherein the process volume comprises a flash vaporization vessel and the compressed steam is used to heat the gas-rich trapping medium in the at least one pre-heating arrangement.

32. 32. The apparatus of claim 22, wherein the gas phase in thermal association with the gas-containing gas phase comprises a water vapor phase, and the apparatus further comprises an indirect heat exchanger arrangement configured to heat a water-rich phase using the gas-containing gas phase to generate the water vapor phase.

33. 33. The apparatus of claim 32, wherein the indirect heat exchanger comprises at least one heat exchanger, at least one condensing heat exchanger, or at least one mixing heat exchanger.

34. The at least one heating arrangement comprises: a first preheating arrangement including a condensing heat exchanger configured to transfer energy from the compressed vapor to heat the gas-rich trapping medium before the gas-rich trapping medium is fed into the process volume and a preheating arrangement; a second pre-heating arrangement configured to transfer thermal energy from the target gas and water phase after passing through the condensing heat exchanger to heat the gas-rich entrapment medium before it is fed to the process volume; 34. The apparatus of any one of claims 22 to 33, comprising:

35. 31. The apparatus of any one of claims 22 to 30, wherein the process volume comprises a desorption vessel, and the at least one heating arrangement comprises at least one mixing heat exchanger configured to heat the gas-rich trapping medium by pumping the compressed steam into the gas-rich trapping medium in the process volume of the desorption vessel or in a volume fluidly connected to the process volume.

36. 36. The apparatus of any one of claims 22 to 35, wherein the vapor recompression system is powered from an electrical source.

37. 37. The apparatus of any one of claims 22 to 36, wherein the vapor recompression system comprises a single stage compressor or a multi-stage compressor.

38. 38. Apparatus according to any one of claims 22 to 37, wherein the vapor recompression system comprises a plurality of compressors connected in series.

39. 39. The apparatus of any one of claims 22 to 38, wherein the vapor recompression system comprises multiple stage compressors, the apparatus further comprising at least one intercooler disposed between each compressor for recovering heat therefrom.

40. 40. The apparatus of claim 39, wherein each compressor has a compression ratio of between 1.1 and 10.

41. 41. Apparatus according to any one of claims 22 to 40, wherein the process vessel has an operating pressure of at least 1 bara, preferably at least 1.5 bara.

42. 42. The apparatus of any one of claims 22 to 41, further comprising a condenser for condensing and recovering trapping medium vapor from the compressed vapor phase.

43. 43. Apparatus according to any one of claims 22 to 42, comprising a condenser for condensing and recovering water vapour from said gas phase in thermal association with said gas-containing vapor phase.

44. 44. The apparatus of any one of claims 22 to 43, fluidly connected to an absorber configured to absorb target gas from a feed gas stream into a capture medium to produce a target gas-rich capture medium that is fed to the regeneration apparatus for regeneration of the capture medium and recovery of absorbed target gas therefrom.

45. 45. Apparatus for removal of a target gas from a feed gas stream comprising an absorber fluidly upstream of a regenerator according to any one of claims 22 to 44.

46. The feed gas stream is 2 , H 2 S, HCl, HF, SO 2 , S.O. 3 , or NO x a target gas selected from at least one of the following: 2 46. ​​The apparatus of any one of claims 22 to 45, comprising:

47. 47. The process of claim 1 , comprising pumping the gas-rich trapping medium through an apparatus as claimed in claim 22 having a heating arrangement for heating the gas-rich trapping medium and thereby causing the trapped gas to dissociate into a gas-rich gas phase, the compressed steam being used to supply thermal energy to the heating arrangement.

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