Carbon dioxide removal unit

Abstract

The present specification describes a method and apparatus for removing carbon dioxide from a synthesis gas. The apparatus includes an absorber, a stripper, and first, second and third heat exchangers. The first heat exchanger and the second heat exchanger together bear the reboiling load of the stripper and are heated with synthesis gas and steam, respectively. A lean absorbent stream is drawn from the stripper and cooled with water in a third heat exchanger, and then returned to the absorber. According to the arrangement structure, the method for efficiently recovering the CO2-rich absorbent is realized.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide removal unit for removing carbon dioxide from a synthesis gas stream. Background Art

[0002] In many processes, acid gases such as CO2 must be removed from the product gas. This is typically accomplished by treating the sour gas containing the unwanted acid gases in an absorber with an absorbent such as an amine. The absorbent chemically and / or physically removes the acid gases from the sour gas to produce a CO2-rich absorbent and a sweetened gas (CO2-lean gas). The absorbent is typically regenerated so it can be reused in the absorber. The regeneration process also releases CO2, which is typically compressed / dehydrated and transported to underground storage or used in chemical manufacturing.

[0003] WO2010 / 120527A2 (Alstom Technology Ltd) describes a process for removing gaseous pollutants from a gas stream, the process comprising: contacting the gas stream with a scrubbing solution to remove gaseous pollutants from the gas stream by absorption into the scrubbing solution, thereby producing a used scrubbing solution; regenerating the used scrubbing solution to remove gaseous pollutants from the used scrubbing solution to provide a regenerated scrubbing solution and a gas containing the removed pollutants. In a first regeneration stage, the gas containing the removed pollutants is cooled to reduce the loss of water vapor. In a preferred embodiment, the regenerated scrubbing solution is reboiled to further remove gaseous pollutants and provide a reboiled scrubbing solution. The reboiled scrubbing solution can be used for heat exchange with the regenerated scrubbing solution and the used scrubbing solution.

[0004] WO2016 / 123386A1 (Fluor Technologies Corporation) describes a process for capturing carbon dioxide in a gas mixture, which includes an absorber, a stripper, and a reboiler. The absorbent is a solvent system including a chemical solvent and a non-aqueous physical solvent. The stripper receives a CO2-rich solvent stream from the absorber and produces carbon dioxide and a lean solvent by using a reboiler in fluid communication with a lower portion of the stripper. In the present reference Figure 1 In the embodiment described in , steam is used to carry the reboiler duty.

[0005] WO2017 / 029145A1 (CasalSA) describes a CO2 removal section for removing CO2 from a synthesis gas containing hydrogen, which includes an absorption section and a stripper. The stripper includes an upper zone and a lower zone, in which a CO2-rich solution from an absorber is flashed to produce a first gaseous stream containing CO2 and a partially regenerated semi-lean solution, and the lower zone is used as a stripping zone, in which the semi-lean solution is stripped to produce a second gaseous stream containing CO2 and a regenerated lean solution. The CO2 removal section includes a sealing device for isolating the first gaseous stream from the second gaseous stream so that they can be output from the stripper separately. A method for improving a CO2 removal unit by introducing a sealing device is also described.

[0006] WO2022 / 008876A1 (Carbon Clean Solutions Limited) describes a method for regenerating a solvent comprising carbon dioxide by passing the solvent comprising carbon dioxide through a low-grade heat regenerator to form a carbon dioxide-lean solvent, and passing the carbon dioxide-lean solvent through a low-grade heat reboiler. The term "low-grade heat" generally refers to a temperature range from 60°C to below 120°C.

[0007] There is a need to further improve the energy efficiency of carbon dioxide removal units. Summary of the invention

[0008] The inventors herein describe a CO2 removal unit that more efficiently utilizes heat streams within a process. The process involves absorbing CO2 in a synthesis gas in an absorber to generate a CO2-rich absorbent. The CO2-rich absorbent is treated in a stripper to remove entrained CO2 and produce a lean absorbent and a CO2-rich overhead product.

[0009] The first important feature of the process is that the stripper can utilize waste heat from both synthesis gas and steam. Specifically, a CO2-rich absorbent is extracted from the stripper and subjected to heat exchange in a first heat exchanger by using synthesis gas and in a second heat exchanger by using steam. The heat exchangers can be arranged in series or in parallel. Steam and synthesis gas together bear the reboiler load of the stripper, which has several advantages. Being able to bear the reboiler load with steam means that the CO2 removal unit can function even if the synthesis gas stream is not available to bear the full reboiler load, which often occurs at plant startup. This reduces CO2 emissions during plant startup. Once the synthesis gas-producing portion of the plant is operating normally, the CO2 removal unit can be turned on so that most of the heating load of the stripper is borne by the synthesis gas.

[0010] The second important feature of the process is that the lean absorbent from the stripper is used as a source of low-grade heat and is treated by heat exchange to produce hot water and cooled lean absorbent. The hot water is typically produced at about 80°C and can be used in a steam production plant. The steam thus produced can be used as "process steam", for example for reforming and / or water-gas shift reactions, or can be used elsewhere in the plant ("steam export"). The lean absorbent stream therefore carries a large amount of the heating load for steam, which would otherwise have to be produced using high-grade heat elsewhere in the plant. Thus, this arrangement reduces overall energy consumption and associated costs.

[0011] In a first aspect, the present invention relates to a method for removing carbon dioxide from synthesis gas, the method comprising the following steps:

[0012] contacting the synthesis gas and the absorbent in an absorber (101, 201, 301) to produce a CO2-lean synthesis gas and a CO2-rich first absorbent stream (114, 214, 314);

[0013] extracting the CO2-rich first absorbent stream from the absorber and transferring the CO2-rich first absorbent stream to a stripper (102, 202, 302);

[0014] One or more CO2-rich second absorbent streams (115, 215a,

[0015] 215b) and heating the one or more CO2-rich second absorbent streams to separate them into one or more absorbent-lean CO2 streams (107a, 107b, 207a, 207b) and one or more CO2-lean absorbent streams (108, 208a, 208b) using a first heat exchanger (103, 203, 303) and a second heat exchanger (105, 205, 305), the first heat exchanger being heated with synthesis gas (104a, 204a) and the second heat exchanger being heated with steam (106a, 206a);

[0016] The one or more absorbent-lean CO2 streams and the one or more CO2-lean absorbent streams

[0017] The agent stream is returned to the stripper;

[0018] withdrawing a CO2-rich gaseous overhead stream from the stripper; and

[0019] withdrawing a lean absorbent stream (109, 209, 309) from the stripper, cooling the lean absorbent stream by heat exchanging with water (111, 211, 311) in a third heat exchanger (110, 210, 310) to produce a cooled lean absorbent stream (113, 213, 313), and returning the cooled lean absorbent stream to the absorber;

[0020] Wherein, the first heat exchanger and the second heat exchanger are arranged in series or in parallel.

[0021] The method is particularly suitable for integration into a process for producing decarbonized synthesis gas (ie a mixture of hydrogen and carbon monoxide), H2, synthetic liquid fuels or ammonia.

[0022] In a second aspect, the present invention relates to an apparatus for removing carbon dioxide from synthesis gas, the apparatus comprising:

[0023] An absorber (101, 201, 301) arranged to contact the synthesis gas with an absorbent to produce a CO2-lean synthesis gas and a CO2-rich first absorbent stream (114,

[0024] 214, 314);

[0025] A stripper (102, 202, 304) is arranged to receive steam from the absorber.

[0026] the first CO2-rich absorbent stream of the receiver;

[0027] a first heat exchanger (103, 203, 303) arranged to heat a CO2-rich second absorbent stream (115, 215a) from the stripper using synthesis gas (104a, 204a) so as to separate the CO2-rich second absorbent stream into an absorbent-lean CO2 stream (107a, 207a) and a CO2-lean absorbent stream (108b, 208b), and arranged to return the absorbent-lean CO2 stream and the CO2-lean absorbent stream to the stripper;

[0028] the stripper;

[0029] a second heat exchanger (105, 205, 305) arranged to heat the CO2-rich second absorbent from the stripper using steam (106a, 206a) in order to separate the CO2-rich absorbent into an absorbent-lean CO2 stream (107b, 207b)

[0030] and a CO2-lean absorbent stream (108b, 208b), and is arranged so that the lean absorbent

[0031] The CO2 stream and the CO2-lean absorbent stream are returned to the stripper;

[0032] a third heat exchanger (110, 210, 310) arranged to receive the lean absorbent stream (109, 209, 309) from the stripper and to heat the stripper using water (111,

[0033] 211, 311) cooling the lean absorbent stream to produce a cooled lean absorbent stream (113,

[0034] 213, 313), and is arranged to return the cooled lean absorbent stream to the absorbent

[0035] Receiver;

[0036] Wherein, the first heat exchanger and the second heat exchanger are arranged in series or in parallel.

[0037] In a third aspect, the present invention relates to a chemical plant for producing decarbonized synthesis gas, H2, synthetic liquid fuel or ammonia, the chemical plant comprising the apparatus according to the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 11 is a flow chart showing an arrangement in which a first heat exchanger and a second heat exchanger are arranged in series. Synthesis gas and absorbent are contacted in an absorber (101) to produce a CO2-lean synthesis gas and a CO2-rich first absorbent stream (114). The CO2-rich first absorbent stream is transported from the absorber (101) to a stripper (102). A CO2-rich second absorbent stream (115) is extracted from the stripper and supplied to the first heat exchanger (103). The heating load of the first heat exchanger is borne by the synthesis gas (104a), wherein the synthesis gas is cooled to produce a cooled synthesis gas (104b). The heat exchange between the synthesis gas (104a) and the CO2-rich second absorbent stream (115) separates the first stream into a CO2-lean absorbent stream (107a) (which is typically a mixture of CO2 and steam) returned to the stripper and a CO2-lean absorbent stream (108a) that is transported to the second heat exchanger (105). The heating duty of the second heat exchanger is borne by steam (106a), which is cooled to produce steam condensate (106b). Heat exchange between the steam (106a) and the CO2-lean absorbent stream (116) further separates the CO2-lean absorbent into a CO2-lean absorbent stream (107b) that is returned to the stripper and a CO2-lean absorbent stream (108b). The lean absorbent stream (109) is withdrawn from the stripper and conveyed to the third heat exchanger (110), where it is cooled using water (111) to produce hot water (112), and the cooled lean absorbent (113) is returned to the absorber.

[0039] Figure 2is a flow chart showing an arrangement in which a first heat exchanger and a second heat exchanger are arranged in parallel. A first absorbent stream (214) rich in CO2 is transported from an absorber (201) to a stripper (202). A second absorbent stream (215a) rich in CO2 is extracted from the stripper and supplied to the first heat exchanger (203). The heating load of the first heat exchanger is borne by a synthesis gas (204a), wherein the synthesis gas is cooled to produce a cooled synthesis gas (204b). The heat exchange between the synthesis gas (204a) and the second absorbent stream (215a) rich in CO2 separates the second absorbent stream rich in CO2 into a CO2 stream (207a) poor in absorbent returned to the stripper and a CO2 poor absorbent stream (208a). A second absorbent stream (215b) rich in CO2 is extracted from the stripper and supplied to a second heat exchanger (205). The heating duty of the second heat exchanger is borne by steam (206a), which is cooled to produce steam condensate (206b). Heat exchange between steam (206a) and the CO2-rich second absorbent stream (215b) further separates the CO2-rich absorbent into a CO2-lean absorbent stream (207b) that is returned to the stripper and a CO2-lean absorbent stream (208b). The lean absorbent stream (209) is extracted from the stripper and conveyed to the third heat exchanger (210), where it is cooled using water (211) to produce hot water (212), and the cooled lean absorbent (213) is returned to the absorber.

[0040] Figure 3 is a flow chart showing an arrangement in which a flash unit is present. A first absorbent stream (314) rich in CO2 is delivered from the absorber (301) to a flash unit (316). The flash unit separates a gaseous CO2 overhead stream (317) and a semi-lean absorbent stream (318), wherein the semi-lean absorbent stream is delivered to the stripper (302). The CO2-rich absorbent (315) is extracted from the stripper and supplied to a first heat exchanger and a second heat exchanger (303 / 305) which may be arranged in series or in parallel (details not shown). In some embodiments, a gaseous CO2-rich overhead stream (319) from the stripper may be returned to the flash unit. A lean absorbent stream (309) is withdrawn from the stripper and passed to a third heat exchanger (310) where it is cooled using water (311) to produce hot water (312) and the cooled lean absorbent (313) is returned to the absorber.

[0041] In a preferred embodiment, the cooled lean absorbent (113, 213, 313) is further cooled by air cooling in a fifth heat exchanger before being returned to the absorber. DETAILED DESCRIPTION

[0042] Any sub-headings are included for convenience only and are not intended to limit the disclosure in any way.

[0043] Any aspect described in conjunction with the process is equally applicable to the device, and vice versa.

[0044] Absorber

[0045] The function of the absorber is to remove CO2 present in the synthesis gas by contacting the synthesis gas with a liquid absorbent. The synthesis gas supplied to the absorber contains H2, CO, CO2, H2O, and may contain unreacted hydrocarbons such as methane. The removal of CO2 by the absorbent may be achieved by chemical absorption and / or physical absorption, and the term "absorbent" is not intended to imply that the absorption is purely chemical. A wide variety of absorbents can be used in the present invention, but amine absorbents are particularly preferred. The absorbent may be a fully recycled absorbent (from a cooled lean absorbent stream), but is typically a mixture of recycled absorbent and fresh make-up absorbent.

[0046] The absorber produces a CO2-lean synthesis gas and a CO2-rich first absorbent stream, wherein the CO2-lean synthesis gas can be sent for further processing (e.g., purification and / or compression). The CO2-rich first absorbent stream is sent for regeneration by a stripper or, in the case of a flash unit, by a flash unit and a stripper.

[0047] The CO2-depleted synthesis gas can be used to produce H2, synthetic liquid fuels, ammonia or other chemicals downstream.

[0048] Flash unit

[0049] The apparatus may include a flash unit located between the absorber and the stripper. The flash unit is arranged to separate the CO2-rich first absorbent stream from the absorber into a CO2 tower top distillate stream and a semi-lean absorbent stream by pressure change, and is arranged to convey the semi-lean absorbent stream to the stripper, where it is separated into a CO2-rich gaseous tower top distillate stream and a lean absorbent stream.

[0050] In some embodiments, the apparatus is arranged to split the semi-lean absorbent stream from the flash unit into a first portion that is sent to the stripper and a second portion that is sent to the absorber. This can have a beneficial effect because it reduces overall reboil energy requirements, reduces absorbent degradation, and enables flexibility in changing syngas operating conditions.

[0051] In a preferred embodiment, the semi-lean absorbent stream is heated by heat exchange with the lean absorbent stream from the stripper before entering the stripper. This arrangement allows for a more efficient use of heat.

[0052] Stripper

[0053] The role of the stripper is to separate the CO2-rich first absorbent stream or, in the case of a flash unit, the semi-lean absorbent stream into a CO2-rich overhead stream and a lean absorbent stream. This is achieved by using a first heat exchanger and a second heat exchanger. The first heat exchanger and the second heat exchanger may be arranged in series or in parallel.

[0054] One or more CO2-rich second absorbent streams are withdrawn from the stripper. The term "second" is used only to distinguish such streams from the CO2-rich first absorbent stream previously described in connection with the absorber. Typically, when the heat exchangers are arranged in series, one CO2-rich second absorbent stream is withdrawn, and when the heat exchangers are arranged in parallel, two CO2-rich second absorbent streams are withdrawn.

[0055] In a series arrangement, a second absorbent stream rich in CO2 is withdrawn from the stripper to a first heat exchanger where it is heated using synthesis gas in order to separate it into an absorbent-lean CO2 stream and a CO2-lean absorbent stream. The absorbent-lean CO2 stream, which is typically a mixture of CO2 and steam containing a small or negligible amount of absorbent, is returned to the stripper. The CO2-lean absorbent stream is conveyed to a second heat exchanger where it is heated using steam in order to generate another absorbent-lean CO2 stream that is returned to the stripper and another CO2-lean absorbent stream. Figure 1 An exemplary arrangement is shown in . In a series arrangement, it is also possible to arrange the second heat exchanger (with steam) first and then the first heat exchanger (with synthesis gas). If the steam and synthesis gas are at different temperatures, the heat exchanger with the colder heat exchange medium should be arranged first and then the heat exchanger with the hotter heat exchange medium.

[0056] In a parallel arrangement, two CO2-rich second absorbent streams are withdrawn from the stripper. The CO2-rich second absorbent stream is heated using synthesis gas in a first heat exchanger in order to separate it into a CO2-lean absorbent stream which is returned to the stripper and a CO2-lean absorbent stream. A similar process is carried out using steam in a second heat exchanger. Figure 2 An exemplary arrangement is shown in FIG.

[0057] Although referred to herein as a "lean absorbent CO2 stream", such a stream will typically contain a significant amount of steam, and steam may be the primary component of such a stream. Separating the CO2-rich second absorbent stream into a lean absorbent CO2 stream and a lean CO2 absorbent stream may also be referred to as "reboiling", wherein the syngas and steam together carry the reboiler load.

[0058] The first heat exchanger and the second heat exchanger bear the heat load for regenerating the CO2-rich absorbent using synthesis gas and steam, respectively. The relative proportions of the heat load borne by the first heat exchanger and the second heat exchanger may change over time. For example, at startup, the second heat exchanger may bear most of the heat load, while at steady state, the first heat exchanger bears most of the heat load.

[0059] During steady state operation, the synthesis gas carries most of the heating duty of the stripper, so it is preferred that if the first and second heat exchangers are arranged in series, the order is: first heat exchanger (heated by the synthesis gas), then the second heat exchanger (heated by the steam). This arrangement makes it possible to control the amount of steam to meet the remaining reboil duty.

[0060] The first and second heat exchangers may be located inside or outside the stripper and the term "extracting CO2-rich absorbent from the stripper" should therefore be understood accordingly. Preferably, the heat exchangers are located outside the stripper as this arrangement is less complex and more reliable.

[0061] The temperature of the synthesis gas and steam supplied to the first heat exchanger and the second heat exchanger should be high enough to desorb CO2 from the CO2-rich absorbent. Typically, the synthesis gas supplied to the first heat exchanger is at least 100°C, such as 120°C to 200°C, preferably 130°C to 170°C. Typically, the steam supplied to the first heat exchanger is at least 100°C, such as 120°C to 200°C, preferably 120°C to 130°C.

[0062] The CO2-rich overhead stream is removed from the top of the stripper. These overhead products can be sent for further processing downstream, such as CO2 compression and dehydration, and optionally, then CO2 transport and storage. In the case of a flash unit, the CO2-rich overhead stream is preferably returned to the flash unit.

[0063] Return to Absorber

[0064] A lean absorbent stream is extracted from the stripper, typically from the bottom of the stripper. This lean absorbent stream needs to be cooled before it is returned to the absorber, because the absorption carried out in the absorber is more efficient when the absorbent is cooled. Water is therefore used in the third heat exchanger to cool the lean absorbent stream. The temperature of the water provided to the third heat exchanger is lower than the temperature of the lean absorbent stream, and is typically about 20°C (e.g., 10°C to 35°C), and is heated to about 80°C (e.g., 70°C to 90°C) by heat exchange with the lean absorbent stream. The water is preferably demineralized water. The products of the third heat exchanger are a cooled lean absorbent stream and a hot water stream.

[0065] The use of water to cool the lean absorbent stream reduces the load on the cooling unit for absorber recycle. The use of low-grade heat from the lean absorbent stream to generate a hot water stream improves overall plant efficiency. The hot water stream can then be used to generate steam, which can be used as a reactant for steam reforming and / or water gas shift reactions elsewhere in the plant, such as in a steam methane reformer (SMR), autothermal reformer (ATR), or water gas shift unit, or can be exported, such as a "steam export". Otherwise, high-grade heat from elsewhere would have to be used to generate steam.

[0066] In some embodiments, the apparatus comprises a fifth heat exchanger arranged to further cool the cooled lean absorbent stream from the third heat exchanger by air cooling. This is more preferred so that the absorbent is cooled as much as possible before it is returned to the absorber. Another benefit of using water to cool the lean absorbent stream in the fifth heat exchanger is that it may allow a smaller air cooler to be used. This reduces operating costs compared to an arrangement where cooling of the lean absorbent is achieved entirely by air cooling.

[0067] In some embodiments, where a flash unit is present, the apparatus comprises a fourth heat exchanger arranged to receive lean absorbent from the stripper and semi-lean absorbent from the flash unit. The lean absorbent from the stripper is cooled by heat exchange with the semi-lean absorbent from the flash unit.

[0068] Example

[0069] right Figure 2 The arrangement shown was simulated. The lean absorbent stream (209) withdrawn from the stripper has a very low residual CO2 content. Cooling the lean absorbent stream in a heat exchanger (210) generates a hot water stream (212) at a temperature of 79°C, which can be used for steam output.

[0070]

[0071]

Claims

1. A method for removing carbon dioxide from synthesis gas, the method comprising the following steps: contacting the synthesis gas and the absorbent in an absorber (101, 201, 301) to produce a CO2-lean synthesis gas and a CO2-rich first absorbent stream (114, 214, 314); extracting the CO2-rich first absorbent stream from the absorber and transferring the CO2-rich first absorbent stream to a stripper (102, 202, 302); One or more CO2-rich second absorbent streams (115, 215a, 215b) and heating the one or more CO2-rich second absorbent streams to use the first heat exchanger (103, 203, 303) and the second heat exchanger (105, 205, 305) to separate them into one or more absorbent-lean CO2 streams (107a, 107b, 207a, 207b) and one or more CO2-lean absorbent streams (108, 208a, 208b), the first heat exchanger is heated by synthesis gas (104a, 204a), and the second heat exchanger is heated by steam (106a, 206a); returning the one or more absorbent-lean CO2 streams and the one or more CO2-lean absorbent streams to the stripper; extracting a CO2-rich gaseous overhead stream from the stripper; as well as A lean absorbent stream (109, 209, 309) is withdrawn from the stripper and cooled by heat exchange with water (111, 211, 311) in a third heat exchanger (110, 210, 310) to produce a cooled lean absorbent stream (113, 213, 313), and returning the cooled lean absorbent stream to the absorber; Wherein, the first heat exchanger and the second heat exchanger are arranged in series or in parallel.

2. The method according to claim 1, wherein: The CO2-rich first absorbent stream is transported to a flash unit (316) located between the absorber and the stripper, the CO2-rich first absorbent stream (314) is separated into a gaseous CO2 tower top distillate stream (317) and a semi-lean absorbent stream (318), and the semi-lean absorbent stream is transported to the stripper.

3. The method according to claim 2, wherein: The CO2-rich gaseous overhead stream (319) from the stripper is returned to the flash unit.

4. The method according to claim 2 or claim 3, wherein: The semi-lean absorbent stream is split and a first portion is sent to the stripper and a second portion is sent to the absorber.

5. The method according to any one of claims 2 to 4, wherein: The lean absorbent stream from the stripper is cooled by heat exchanging with the semi-lean absorbent stream from the flash unit in a fourth heat exchanger.

6. The method according to any one of claims 1 to 5, wherein: The cooled lean absorbent stream from the third heat exchanger is further cooled by air cooling in a fifth heat exchanger.

7. The method according to any one of claims 1 to 6, wherein: The first heat exchanger and the second heat exchanger are arranged in parallel.

8. The method according to any one of claims 1 to 6, wherein: The first heat exchanger and the second heat exchanger are arranged in series.

9. The method according to any one of claims 1 to 8, wherein: The temperature of the synthesis gas supplied to the first heat exchanger is at least 100°C.

10. The method according to any one of claims 1 to 9, wherein: The temperature of the steam supplied to the second heat exchanger is at least 100°C.

11. The method according to any one of claims 1 to 10, wherein: The hot water flow generated by the third heat exchanger is used to generate steam.

12. The method according to any one of claims 1 to 11, wherein: The absorbent is an amine.

13. The method according to any one of claims 1 to 12, wherein: The CO 2 -depleted synthesis gas is used to produce H 2 , synthetic liquid fuels, ammonia or other chemicals downstream.

14. An apparatus for removing carbon dioxide from synthesis gas, the apparatus comprising: an absorber (101, 201, 301) arranged to contact the synthesis gas with an absorbent to produce a CO2-lean synthesis gas and a CO2-rich first absorbent stream (114, 214, 314); a stripper (102, 202, 304) arranged to receive the CO2-rich first absorbent stream from the absorber; a first heat exchanger (103, 203, 303) arranged to heat a CO2-rich second absorbent stream (115, 215a) from the stripper using synthesis gas (104a, 204a) so as to separate the CO2-rich second absorbent stream into an absorbent-lean CO2 stream (107a, 207a) and a CO2-lean absorbent stream (108b, 208b), and arranged to return the absorbent-lean CO2 stream and the CO2-lean absorbent stream to the stripper; a second heat exchanger (105, 205, 305) arranged to heat a CO2-rich second absorbent from the stripper using steam (106a, 206a) so as to separate the CO2-rich absorbent into an absorbent-lean CO2 stream (107b, 207b) and a CO2-lean absorbent stream (108b, 208b), and arranged to return the absorbent-lean CO2 stream and the CO2-lean absorbent stream to the stripper; a third heat exchanger (110, 210, 310) arranged to receive a lean absorbent stream (109, 209, 309) from the stripper and to cool the lean absorbent stream using water (111, 211, 311) to produce a cooled lean absorbent stream (113, 213, 313), and arranged to return the cooled lean absorbent stream to the absorber; Wherein, the first heat exchanger and the second heat exchanger are arranged in series or in parallel.

15. The apparatus according to claim 14 comprises a flash unit (316), which is located between the absorber and the stripper, is arranged to separate the CO2-rich first absorbent flow from the absorber into a CO2 tower top distillate flow (317) and a semi-lean absorbent flow (318) in the flash unit, and is arranged to transport the semi-lean absorbent to the stripper.

16. Apparatus according to claim 15, arranged to return CO2-rich overheads from the stripper to the flash unit.

17. Apparatus according to claim 15 or claim 16 arranged to split semi-lean absorbent from the flash unit into a first portion which is passed to the stripper and a second portion which is passed to the absorber.

18. The apparatus process according to any one of claims 15 to 17, comprising a fourth heat exchanger arranged to receive lean absorbent from the stripper and semi-lean absorbent from the flash unit, and to cool the lean absorbent.

19. Apparatus according to any one of claims 14 to 18, comprising a fifth heat exchanger arranged to further cool the cooled lean absorbent from the third heat exchanger by air cooling.

20. Apparatus according to any one of claims 14 to 19, wherein: The first heat exchanger and the second heat exchanger are arranged in parallel.

21. Apparatus according to any one of claims 14 to 19, wherein: The first heat exchanger and the second heat exchanger are arranged in series.

22. A chemical plant for producing decarbonized synthesis gas, H2, synthetic liquid fuel ammonia or other chemicals, the chemical plant comprising an apparatus according to any one of claims 14 to 21.

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