A method and system for the removal of carbon dioxide from carbon capture solvents using compressed solvent vapour

Abstract

The present invention relates to a method and system for the removal of carbon dioxide (CO2) from an upstream gas with a solvent-based system. Typically, the upstream gas is a flue gas. However, the gas can also be cement-kiln gas, blast furnace gas, syngas, biogas or other gases which require the removal of CO2. In particular, the present invention relates to a method and a system for the regeneration of solvents and the removal of CO2 from CO2 rich solvent streams wherein the method and system use heat from a compressed vapour for the regeneration.

Description

[0001] Title: A method and system for the removal of carbon dioxide from carbon capture solvents using compressed solvent vapour

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a method and system for the removal of carbon dioxide (CO2) from an upstream gas with a solvent-based system. Typically, the upstream gas is a flue gas. However, the gas can also be cement-kiln gas, blast furnace gas, syngas, biogas or other gases which require the removal of CO2. In particular, the present invention relates to a method and a system for the regeneration of solvents and the removal of CC>2 from CO2 rich solvent streams wherein the method and system use heat from a compressed solvent vapour for the regeneration.

[0004] BACKGROUND OF THE INVENTION

[0005] Flue gases from power plants and other industrial activities include pollutants, for example greenhouse gases. One such greenhouse gas is CO2. Emissions of C02to the atmosphere from industrial activities are of increasing concern to society and are therefore becoming increasingly regulated. To reduce the amount of CO2 being released into the atmosphere, CO2 capture technology can be applied. The selective capture of C02 not only minimizes the amount of CO2 released into the atmosphere, but also allows CO2 to be re-used or geographically sequestered. CO2 capture methods can be applied to CO2 capture from flue gases and industrial gases, e.g., emissions from plants that burn hydrocarbon fuel. CO2 capture methods are also applicable to CO2 capture from coal, gas and oil-fired boilers, combined cycle power plants, coal gasification, hydrogen plants, biogas plants, waste to energy plants, steel plants, refineries, cement kilns, blast furnaces, or any other plant which produces a flue gas.

[0006] CO2 capture methods can be divided into physical adsorbents and chemical absorbents (commonly referred to as carbon capture solvents). For CO2 capture methods, the carbon capture solvent removes CC>2from one or more gas streams. The CO2 in the gas streams selectively reacts with components in the solvent, resulting in CO2 being removed from the gas phase and absorbed by the solvent to form a CO2 rich solvent. The CO2 rich solvent is then heated resulting in CO2 being released back into the gas phase and the CO2 rich solvent being depleted of its CO2 content resulting in the formation of a CO2 lean solvent. The CO2 lean solvent is recycled within the system to capture additional CO2. Examples of known methods using a carbon capture solvent to remove CC>2from a flue gas include the methods described in CN107970743, US2016 / 0166976, US2011 / 0113965 and US20160166976A (all incorporated by reference in their entirety).

[0007] Figure 1 illustrates a schematic diagram 100 of a conventional system 100 for capturing CO2 from flue gases. In the conventional system 100, CO2 is separated from a mixture of gases using a solvent (initially a CO2 lean solvent), which selectively reacts with the CO2 (to form a CO2 rich solvent). After the CO2 has reacted with the solvent (CO2 lean solvent), the solvent (CO2 rich solvent) can be regenerated (to reform CO2 lean solvent) using heat to release the CO2 and regenerate the solvent for further CO2 processing.

[0008] As shown in Figure 1 , a flue gas 101 containing CO2 enters the system 100 through flue gas pretreatment system 102. The temperature of the flue gas 101 when entering the system 100 is typically greater than 100°C, typically from 120 to 200°C. The pressure of the flue gas 101 when entering the system 100 is typically at ambient pressure.

[0009] In the flue gas pre-treatment system 102, flue gas 101 undergoes pre-treatment to form flue gas 101 a. The pre-treatment includes cooling and the removal of (some) impurities. For example, in the flue gas pre-treatment system 102, the flue gas 101 is cooled to a temperature of typically 35°C. Furthermore, any dust, SO2 and NO2 present in the flue gas 101 is removed in the pre-treatment system 102. Typically, the flue gas 101 is cooled through the use of a direct contact cooler. In the direct contact cooler, the flue gas 101 is contacted with a recirculating loop of cool water in a countercurrent configuration. Through this contact, the flue gas 101 is cooled to the desired temperature. Typically, any dust, SO2 and NO2 present in the flue gas 101 is removed with an alkali solution.

[0010] The flue gas 101 a optionally passes through a booster fan. The booster fan increases the pressure of flue gas 101 a to compensate for the pressure drop through the system, thereby ensuring that the pressure of the resultant CO2 lean flue gas (called CO2 lean flue gas 101 b in this system) is at the same pressure as flue gas 101 .

[0011] The flue gas 101 a enters the absorber 103, where the flue gas 101 a is contacted with a low-heat, CO2 lean solvent 116f in a counter-current configuration. The low-heat, CC>2 lean solvent 116f is typically at a temperature of 35°C. The low-heat, CO2 lean solvent 116f enters the absorber 103 via a liquid distributor (not shown in Figure 1) positioned at the top of the absorber 103, and cascades down through the absorber 103. The flue gas 101 a rises through the absorber 103. The absorber 103 contains packing to maximise the surface area to volume ratio. The packing is shown by references 103a, 103b and 103c. Typically, the low-heat, CC>2 lean solvent 116f enters the absorber 103 above packing 103b and below packing 103c. The location of the packing and the height of the packing can be optimised on a case-by-case basis. The absorber 103 additionally includes a demister 103d.

[0012] The low-heat, CO2 lean solvent 116f comprises active components which react with the CO2 in the flue gas 101 a. The reaction is exothermic and low temperatures favour the absorption of CO2 into the low- heat, CC>2 lean solvent 116f from the flue gas 101 a. To maintain a low temperature, an inter-cooling section is included between packing 103a and 103b. Once the low-heat, CO2 lean solvent 116f has passed through packing 103b, a low-heat, CO2 semi-rich solvent 106a is formed. The low-heat, CO2 semi-rich solvent 106a is at a temperature of from 40 to 60°C. Instead of passing directly down through the absorber 103, the low-heat, CO2 semi-rich solvent 106a passes to an absorber interstage pump 104 to form low-heat, CO2 semi-rich solvent 106b. The absorber interstage pump 104 is used to feed the low-heat, CO2 semi-rich solvent 106b back into the absorber 103. The low-heat, CO2 semirich solvent 106b then passes to an absorber interstage cooler 105 forming low-heat, CO2 semi-rich solvent 106c. The absorber interstage cooler 105 removes any excess heat formed during the exothermic CO2 absorption reaction. In the absorber interstage cooler 105, the low-heat, CO2 semirich solvent 106b is typically cooled to a temperature of from 40 to 60°C to form low-heat, CO2 semirich solvent 106c. The low-heat, CO2 semi-rich solvent 106c then continues to cascade through absorber 103. Advantageously, by cooling the solvent, the temperature of the solvent is reduced. A solvent with a reduced temperature will be able to have an increased loading of CO2, which in turn reduces the heat of desorption energy required in the regenerator 110.

[0013] When the low-heat, CO2 semi-rich solvent 106c reaches the bottom of the absorber 103, the solvent is rich in CC>2 and forms low-heat, CC>2 rich solvent 109a. The low-heat, CC>2 rich solvent 109a is typically at a temperature of from 35 to 50°C.

[0014] The low-heat, CO2 rich solvent 109a passes through a CO2 rich solvent pump 107 to form a low-heat, CO2 rich solvent 109b. The low-heat CO2 rich solvent 109b is typically at a temperature of from 35 to 50°C.

[0015] As the flue gas 101 a passes up through the absorber 103, it is depleted of CO2 and eventually forms CO2 lean flue gas 101 b. When the flue gas 101 a has passed through packing 103b, CO2 lean flue gas 101 b is formed. The CC>2 lean flue gas 101 b then passes through a water wash section in packing 103c to recover any water and / or solvent that may be present in the flue gas 101 b. The solvent is removed from the flue gas 101 b by reducing the temperature of the flue gas 101 b to a temperature of typically 35°C by contacting the flue gas 101 b with wash water 120c. Once the wash water 120c has cooled the flue gas 101 b, wash water 120a is formed. Wash water 120a passes through a water wash pump 118 to form wash water 120b. The water wash pump 118 provides sufficient pressure to feed the wash water 120b back into the absorber 103. Wash water 120b passes through a water wash cooler 119, which cools the wash water 120b to form wash water 120c.

[0016] Once the flue gas 101 b has been washed in the water wash section, the flue gas 101 b continues to pass up through the absorber 103 to be released from the top of the absorber 103. The absorber 103 further includes a demister 103d, through which the CO2 lean flue gas 101 b passes through before leaving the absorber 103. The demister 103d is used to remove liquid droplets from the CC>2 lean flue gas 101 b.

[0017] The low-heat, CC>2 rich solvent 109b is regenerated in regenerator 110, to reform low-heat, CC>2 lean solvent 116f. The regenerator 110 contains packing to maximise the surface area to volume ratio. The packing is shown by references 1 10a, 110b and 110c in Figure 1 . The packing 110a is present in the half of the regenerator 110 connected to a reboiler 1 15, this part is the bottom of the regenerator 110. The packing 110c is present in the part of the regenerator 110 connected to a condenser 111 , this part is the top of the regenerator 110. Packing 110b is present between packing 110a and 110c. Packings 110a and 110b are placed in specific locations in the regenerator 1 10 to maintain the required temperature profile in the regenerator 110. Packing 110c is placed in the specified location to wash any vapours present at the top of the regenerator 1 10 and to recover the solvent and water vapours that have risen to the top of the regenerator 110.

[0018] The low-heat, CO2 rich solvent enters the regenerator 110 via a cross-over heat exchanger 108. The low-heat CO2 rich solvent 109b passes to the cross-over heat exchanger 108. In the cross-over heat exchanger 108, the low-heat, CC>2 rich solvent 109b is heated by a high-heat, CC>2 lean solvent 116d to form high-heat, CC>2 rich solvent 109c. The high-heat, CC>2 rich solvent 109c is typically at a temperature of 117°C.

[0019] The high-heat, CC>2 rich solvent 109c enters the regenerator 110 above packing 110b and cascades down the regenerator 110 to below packing 1 10a. Inside the regenerator, the high-heat, CO2 rich solvent 109c is heated further through contact with a high-heat vapour 116b. Typically, the high-heat vapour 116b flows upwards through the regenerator 110, counter-current to the high-heat, CO2 rich solvent 109c. Typically, the high-heat vapour 116b is at a temperature of 124°C. Upon heating, the reaction between the active components of the solvent and CO2 reverses, releasing CC>2 gas and forming a high-heat, CO2 semi-lean solvent 116a. The high-heat, CO2 semi-lean solvent 116a is at a temperature of from 118 to 124°C.

[0020] The CO2 gas and any high-heat vapour 1 16b present at the top of regenerator 1 10 form stream 1 12a. Stream 112a passes to a stripper condenser 111 . The condenser 111 forms a condensate 1 12b from the stream 112a, which passes to a reflux drum 113. The reflux drum 1 13 separates the condensate 112b into a gaseous CO2 112c and a reflux condensate 112d. The reflux condensate 112d passes to a reflux pump 114 to form reflux condensate 112e. The reflux pump 1 14 is used to move the reflux condensate 112e back into the regenerator 110. The reflux condensate 112e then passes back into the regenerator 1 10 above the packing 110c. Having passed through the condenser 111 , the condensate 112b and the subsequently formed reflux condensate 112d and reflux condensate 112e are all typically at a temperature of from 35 to 40°C.

[0021] The gaseous CO2 112c is the CO2 product stream and can be used in downstream processes.

[0022] The high-heat, CO2 semi-lean solvent 116a is fed into a reboiler 115. Typically, the reboiler 115 is operating at a temperature of 120°C or greater. Within the reboiler 115, a first part of the high-heat, CO2 semi-lean solvent 116a is boiled resulting in the formation of the high-heat vapour 116b. A second part of the high-heat, CO2 semi-lean solvent 116a leaves the reboiler 115 as high-heat, CO2 lean solvent 116c. Typically, the high-heat, CO2 lean solvent 116c is at a temperature of 124°C. The high-heat, CO2 lean solvent 116c passes to a CO2 lean solvent pump 121 to form high-heat, CO2 lean solvent 116d. High-heat, CO2 lean solvent 116d is at a temperature of 124°C. High-heat CC>2 lean solvent 116d passes into the cross-over heat exchanger 108 and is cooled through contact with the low-heat, CC>2 rich solvent 109b to form low-heat, CC>2 lean solvent 116e. Typically, the low-heat, CO2 lean solvent 116e is at a temperature of 45°C. The low-heat, CC>2 lean solvent 116e then passes through a CO2 lean solvent cooler 117 to form low-heat, CO2 lean solvent 116f before entering the absorber column 103. The low-heat, CO2 lean solvent 116f is at a temperature of 35°C. The low-heat, CO2 lean solvent 116f is now ready to repeat the absorption process again.

[0023] In typical CO2 capture methods that use carbon capture solvents, regeneration of the carbon capture solvents requires a high amount of energy. The energy required can be split into three factors: (1) heat of absorption, (2) solvent sensible heat, and, (c) latent heat of vapourisation of water. The heat of absorption is limited by solvent chemistry, the solvent sensible heat is limited by the exchange of heat between carbon dioxide rich and carbon dioxide lean solvents and the latent heat of vapourisation is dependent on the pressure and temperature of the regenerator as well as the water content of the solvent. Regeneration of the carbon capture solvent uses approximately 70 to 80 % of the total cost of the carbon capture plant, and thus regeneration of the carbon capture solvents is one of the largest operating costs for capturing CO2.

[0024] To address this need, the conventional method and system for capturing CO2 from flue gases has been adapted to reduce the energy used in regeneration.

[0025] SUMMARY OF THE INVENTION

[0026] The present invention relates to a method and system for the removal of carbon dioxide (CO2) from an upstream gas with a solvent-based system. Typically, the upstream gas is a flue gas. However, the gas can also be cement-kiln gas, blast furnace gas, syngas, biogas or other gases which require the removal of CO2. In particular, the present invention relates to a method and a system for the regeneration of solvents and the removal of CC>2 from CO2 rich solvent streams wherein the method and system use heat from a compressed solvent vapour for the regeneration.

[0027] Representative features of the present invention are set out in the following clauses, which stand alone or may be combined, in any combination, with one or more features disclosed in the text and / or figures of the specification.

[0028] The present invention is as set out in the following clauses:

[0029] 1 . A method for regenerating a solvent comprising carbon dioxide (CO2), the method comprising: providing a CO2 lean solvent; passing the CO2 lean solvent into a reboiler, wherein a first part of the CO2 lean solvent is heated to form a CO2 lean solvent vapour and wherein a second part of the CO2 lean solvent leaves the reboiler to further steps in regenerating the solvent comprising carbon dioxide (CO2); compressing the CO2 lean solvent vapour to form a compressed CO2 lean solvent vapour; passing the compressed CO2 lean solvent vapour through a regenerator; providing a CO2 rich solvent; passing the CO2 rich solvent through the regenerator, wherein heat from the compressed CO2 lean solvent vapour heats the CO2 rich solvent to form a CO2 lean solvent.

[0030] 2. The method of clause 1 , wherein the method further comprises the step of: combining the compressed CO2 lean solvent vapour with a fluid to reduce the temperature of the compressed CO2 lean solvent vapour.

[0031] 3. The method of clause 2, wherein the fluid is: a reflux condensate; or, a CO2 rich solvent; or, a preheated reflux condensate.

[0032] 4. The method of clause 2 or clause 3, wherein the fluid is a reflux condensate and the method further comprises the step of: combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid in a reflux condensate heater; optionally, wherein the compressed CO2 lean solvent vapour is heat exchanged with the fluid in a reflux condensate heater.

[0033] 5. The method of clause 2 or clause 3, wherein the fluid is a CO2 rich solvent and the method further comprises the step of: combined or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid in a CO2 rich solvent preheater; optionally, wherein the compressed CO2 lean solvent vapour is heat-exchanged with the fluid in a CO2 rich solvent preheater.

[0034] 6. The method of clause 2 or clause 3, wherein the fluid is a preheated reflux condensate and the method further comprises the step of: combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid in a reflux condensate vaporiser; optionally, wherein the compressed CO2 lean solvent vapour is heat-exchanged with the fluid in a reflux condensate vaporiser. 7. The method of any one of clauses 1 to 6, wherein the temperature of the compressed CO2 lean solvent vapour is at from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C.

[0035] 8. The method of any one of clauses 2 to 7, wherein upon combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

[0036] 9. The method of any one of clauses 2 to 8, wherein the fluid is a reflux condensate or a CO2 rich solvent, and the fluid is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C prior to combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid.

[0037] 10. The method of any one of clauses 2 to 9, wherein the fluid is a reflux condensate and upon combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

[0038] 11 . The method of any one of clauses 2 to 9, wherein the fluid is a CO2 rich solvent and upon combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or 137 °C.

[0039] 12. The method of any one of clauses 2 to 8, wherein the fluid is a preheated reflux condensate, and the fluid is at a temperature of from 90 to 120°C, or, from 100 to 110°C, or, at 105°C prior to combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid.

[0040] 13. The method of any one of clauses 2 to 8 or clause 12, wherein the fluid is a preheated reflux condensate and upon combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

[0041] 14. The method of any one of clauses 1 to 13, wherein the CO2 lean solvent has a carbon dioxide concentration of from 0.0 to 1.0 mol L-1.

[0042] 15. The method of any one of clauses 1 to 14, wherein the CO2 rich solvent has a carbon dioxide concentration of from greater than 2.0 to 4.0 mol L-1.

[0043] 16. The method of any one of clauses 1 to 15, wherein the CO2 semi-lean solvent has a carbon dioxide concentration of from greater than 1 .0 to 1 .5 mol L-1. 17. The method of any one of clauses 1 to 16, wherein the CO2 semi-rich solvent has a carbon dioxide concentration of from greater than 1 .5 to 2.0 mol L-1.

[0044] 18. The method of any one of clauses 1 to 17, wherein the regenerator operates at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C, or, from 130 to 140°C, or, 136°C.

[0045] 19. The method of any one of clauses 1 to 18, wherein the regenerator operates at a pressure of from 0.8 to 3.0 bar(g), or, from 1 .5 to 2.5 bar(g), or, at 2.0 bar(g).

[0046] 20. The method of any one of clauses 1 to 19, wherein the step of providing a CO2 rich solvent further comprises: contacting a flue gas with a CO2 lean solvent within one, two, three, four, five, six, seven, eight, nine or ten, or more, absorber column(s), wherein the absorber column(s) is (are) in fluid communication with the regenerator.

[0047] 21 . The method of clause 20, wherein the absorber column(s) is (are) in fluid communication with the regenerator through at least one cross-over heat exchanger.

[0048] 22. The method of any one of clauses 1 to 21 , wherein the CO2 lean solvent and / or the CO2 rich solvent is / are an intensified solvent; optionally, an intensified solvent comprising a tertiary amine, or, a secondary amine, or, a primary amine; optionally, an intensified solvent further comprising a tertiary amine, a sterically hindered amine, a polyamine, a salt and water; optionally, wherein the solvent is CDRMax® or, MEA.

[0049] 23. The method of any one of clauses 20 to 22, wherein the flue gas is from a coal, gas and / or oil- fired boiler, combined cycle power plant, coal gasification plant, hydrogen plant, biogas plant, waste to energy plant, steel plants, refineries, cement kiln, blast furnace, or any other plant which produces a flue gas.

[0050] 24. The method of any one of clauses 20 to 23, wherein the flue gas has an initial carbon dioxide (CO2) concentration of from 2.2 volume % (dry) to 51 volume % (dry), or, from 3 volume % (dry) to 12 volume % (dry), or, from 15 volume % (dry) to 22 volume % (dry), or, from 30 volume % (dry) to 45 volume % (dry).

[0051] 25. The method of any one of clauses 1 to 24, wherein the regenerator comprises or consists of a packed column, a static column or a Rotary Packed Bed (RPB). 26. The method of clause 25, wherein the regenerator comprises a packed column and where the packed column comprises one, two, three, four, five, six, seven, eight, nine or ten, or more, packing sections.

[0052] 27. The method of any one of clauses 20 to 26, wherein the absorber column(s) comprises (comprise), or consists (consist), of a packed column, a static column, or, a rotating packed bed.

[0053] 28. The method of any one of clauses 20 to 27, wherein the absorber column comprises a packed column and wherein the packed column comprises one, two, three, four, five, six, seven, eight, nine or ten, or more, packing sections.

[0054] 29. A system for regenerating a solvent comprising carbon dioxide (CO2), the system comprising: a regenerator; a reboiler configured to heat a CO2 lean solvent to form a CO2 lean solvent vapour; a compressor configured to compress the CO2 lean solvent vapour to form a compressed CO2 lean solvent vapour; and wherein the regenerator is configured to exchange heat between the compressed CO2 lean solvent vapour and a CO2 rich solvent so as to remove CO2 from the CO2 rich solvent to form a CO2 lean solvent.

[0055] 30. The system of clause 29, wherein the system is further configured to combine the compressed CO2 lean solvent vapour with a fluid.

[0056] 31 . The system of clause 30, wherein the system is further configured to combine the compressed CO2 lean solvent vapour with the fluid prior to exchanging heat between the compressed CO2 lean solvent vapour and the CO2 rich solvent.

[0057] 32. The system of clause 30 or clause 31 , wherein the fluid is: a reflux condensate; or, a CO2 rich solvent; or, a preheated reflux condensate.

[0058] 33. The system of any one of clauses 30 to 32, wherein the fluid is a reflux condensate and the system is configured to combine or mix or heat exchange the compressed CO2 lean solvent vapour with the fluid in a reflux condensate heater; optionally, wherein the system is configured to heat exchange the compressed CO2 lean solvent vapour with the fluid in a reflux condensate heater. 34. The system of any one of clauses 30 to 32, wherein the fluid is a CO2 rich solvent and the system is configured to combine or mix or heat exchange the compressed CO2 lean solvent vapour with the fluid in a CO2 rich solvent preheater optionally, wherein the system is configured to heat exchange the compressed CO2 lean solvent vapour with the fluid in a CC>2 rich solvent preheater.

[0059] 35. The system of any one of clauses 30 to 32, wherein the fluid is a preheated reflux condensate and the system is configured to combine or mix or heat exchange the compressed vapour with the fluid in a reflux condensate vaporiser; optionally, wherein the system is configured to heat exchange the CO2 lean solvent vapour with the fluid in a reflux condensate vaporiser.

[0060] 36. The system of any one of clauses 29 to 35, wherein the temperature of the compressed CO2 lean solvent vapour is at from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C.

[0061] 37. The system of any one of clauses 30 to 36, wherein upon combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

[0062] 38. The system of any one of clauses 30 to 37, wherein the fluid is a reflux condensate or a CO2 rich solvent, and the fluid is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C prior to combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid.

[0063] 39. The system of any one of clauses 30 to 38, wherein the fluid is a reflux condensate and upon combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

[0064] 40. The system of any one of clauses 30 to 38, wherein the fluid is a CO2 rich solvent and upon combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or 137 °C.

[0065] 41 . The system of any one of clauses 30 to 37, wherein the fluid is a preheated reflux condensate, and the fluid is at a temperature of from 90 to 120°C, or, from 100 to 110°C, or, at 105°C prior to combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid. 42. The system of any one of clauses 30 to 37 or claim 41 , wherein the fluid is a preheated reflux condensate and upon combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

[0066] 43. The system of any one of clauses 29 to 42, wherein the CO2 lean solvent has a carbon dioxide concentration of from 0.0 to 1.0 mol L-1.

[0067] 44. The system of any one of clauses 29 to 43, wherein the CO2 rich solvent has a carbon dioxide concentration of from greater than 2.0 to 4.0 mol L-1.

[0068] 45. The system of any one of clauses 29 to 44, wherein the CO2 semi-lean solvent has a carbon dioxide concentration of from greater than 1 .0 to 1 .5 mol L-1.

[0069] 46. The system of any one of clauses 29 to 45, wherein the CO2 semi-rich solvent has a carbon dioxide concentration of from greater than 1 .5 to 2.0 mol L-1.

[0070] 47. The system of any one of clauses 29 to 46, wherein the regenerator operates at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C, or, from 130 to 140°C, or, 136°C.

[0071] 48. The system of any one of clauses 29 to 47, wherein the regenerator operates at a pressure of from 0.8 to 3.0 bar(g), or, from 1 .5 to 2.5 bar(g), or, at 2.0 bar(g).

[0072] 49. The system of any one of clauses 29 to 48, wherein the system is further configured to: contact a flue gas with a CO2 lean solvent within one, two, three, four, five, six, seven, eight, nine or ten, or more, absorber column(s), wherein the absorber column(s) is (are) in fluid communication with the regenerator.

[0073] 50. The system of clause 49, wherein the absorber column(s) is (are) in fluid communication with the regenerator through at least one cross-over heat exchanger.

[0074] 51 . The system of any one of clauses 29 to 51 , wherein the CO2 lean solvent and / or the CO2 rich solvent is / are an intensified solvent; optionally, an intensified solvent comprising a tertiary amine, or, a secondary amine, or, a primary amine; optionally, an intensified solvent further comprising a tertiary amine, a sterically hindered amine, a polyamine, a salt and water; optionally, wherein the solvent is CDRMax®, or, MEA.

[0075] 52. The system of any one of clauses 49 to 51 , wherein the flue gas is from a coal, gas and / or oil-fired boiler, combined cycle power plant, coal gasification plant, hydrogen plant, biogas plant, waste to energy plant, steel plants, refineries, cement kiln, blast furnace, or any other plant which produces a flue gas.

[0076] 53. The system of any one of clauses 49 to 52, wherein the flue gas has an initial carbon dioxide (CO2) concentration of from 2.5 volume % (dry) to 51 volume % (dry), or, from 3 volume % (dry) to 12 volume % (dry), or, from 15 volume % (dry) to 22 volume % (dry), or, from 30 volume % (dry) to 45 volume % (dry).

[0077] 54. The system of any one of clauses 29 to 53, wherein the regenerator comprises or consists of a packed column, a static column or a Rotary Packed Bed (RPB).

[0078] 55. The system of any one of clauses 54, wherein regenerator comprises a packed column and wherein the packed column comprises one, two, three, four, five, six, seven, eight, nine or ten, or more, packing sections.

[0079] 56. The system of any one of clauses 49 to 55, wherein the absorber column(s) comprises (comprise), or consists (consist), of a packed column, a static column, or, a Rotary Packed Bed (RPB).

[0080] 57. The system of any one of clauses 49 to 56, wherein the absorber column comprises a packed column and wherein the packed column comprises one, two, three, four, five, six, seven, eight, nine or ten, or more, packing sections.

[0081] DETAILED DESCRIPTION

[0082] Embodiments of the invention are described below with reference to the accompanying drawings. The accompanying drawings illustrate various embodiments of systems, methods, and embodiments of various other aspects of the disclosure. Any person with ordinary skills in the art will appreciate that the illustrated element boundaries (e.g., boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. It may be that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another and vice versa. Furthermore, elements may not be drawn to scale. Non-limiting and non-exhaustive descriptions are described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles.

[0083] Figure 1 is a schematic diagram of a conventional system 100 that is used in capturing CO2 from flue gases. Figure 2 is a schematic diagram of a system 200 according to the present invention.

[0084] Figure 3 is a schematic diagram of a system 300 according to the present invention.

[0085] Figure 4 is a schematic diagram of a system 400 according to the present invention.

[0086] Figure 5 is a schematic diagram of a system 500 according to the present invention.

[0087] Figure 6 is a schematic diagram of a system 600 according to the present invention.

[0088] Figure 7 is a schematic diagram of a system 700 according to the present invention.

[0089] Embodiments of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings in which like numerals represent like elements throughout the several figures, and in which example embodiments are shown. Embodiments of the claims may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0090] The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the preferred systems and methods are now described.

[0091] Definitions

[0092] Some of the terms used to describe the present invention are set out below:

[0093] “Absorber” refers to a part of a system where components of a solvent (CO2 lean solvent) uptake CO2 from the gaseous phase to the liquid phase to form a CO2 rich solvent. An absorber contains trays or packing (random or structured), which provides transfer area and intimate gas-liquid contact. The absorber may be a column. The absorber may be a static column or a Rotary Packed Bed (RPB).

[0094] “CC>2 lean solvent” refers to solvent with a relatively low concentration of carbon dioxide. In a carbon dioxide capture method, a CO2 lean solvent for contact with flue gases typically has a concentration of carbon dioxide from 0.0 to 1 .0 mol L-1. “CC>2 rich solvent” refers to a solvent with a relatively high concentration of carbon dioxide. In a carbon dioxide capture method, the CO2 rich solvent after contact with flue gases typically has a concentration of carbon dioxide from greater than 2.0 to 4.0 mol L-1.

[0095] “CO2 semi-lean solvent” refers to solvent with a relatively low concentration of carbon dioxide. In a carbon dioxide capture method, a CO2 lean solvent for contact with flue gases typically has a concentration of carbon dioxide from greater than 1.0 to 1.5 mol L-1.

[0096] “CO2 semi-rich solvent” refers to a solvent with a relatively high concentration of carbon dioxide. In a carbon dioxide capture method, the CO2 rich solvent after contact with flue gases typically has a concentration of carbon dioxide from greater than 1.5 to 2.0 mol L-1.

[0097] “Combining” refers to when two or more substances are merged to form a new substance. The substances may be the same or the substances may be different (i.e., distinct from the other substances).

[0098] “Condenser” refers to a device that is used to cool CO2 -containing vapours from the top of the regenerator. Typically, the condenser is used to cool any CC>2-containing vapours as well as other fluids such as CO2 lean solvents, water vapours and / or compressed solvent vapours at the top of a regenerator.

[0099] “Counter-current configuration” refers to a fluid moving in an opposite direction to another fluid. The fluids can be the same fluids or different fluids. The term “fluid” includes “vapours”.

[0100] “Cross-over heat exchanger” refers to a part of the system where one liquid solvent is heated, whilst another liquid solvent is cooled, because the liquids are in thermal connection. For example, a liquid solvent (e.g., a low-heat CO2 rich solvent) can be heated from the heat of another liquid solvent (e.g., a high-heat CO2 lean solvent).

[0101] “Direct contact cooler” refers to a part of a system where a gas stream is cooled. Typically, the gas stream is cooled by contacting a recirculating loop of cool water in a packed bed or tray or spray type arrangement, for a better gas-liquid contact.

[0102] “Flue gas” is a gas exiting to the atmosphere via a pipe or channel that acts as an exhaust from a boiler, furnace or a similar environment, for example a flue gas may be the emissions from power plants and other industrial activities that burn hydrocarbon fuel such as coal, gas and oil-fired power boilers, combined cycle power plants, coal gasification, hydrogen plants, biogas plants, waste to energy plants, steel plants, refineries, cement kilns, blast furnaces, or any other plant which produces a flue gas. A carbon dioxide rich flue gas is a flue gas that comprises carbon dioxide from 2.5 volume % to 51 volume %. “Heat of absorption” refers to the relationship between the CO2 loading of a carbon capture solvent and the components that form the carbon capture solvent. The heat of absorption increases with a decrease in CO2 loading. Hence, increasing the CO2 loading of the carbon capture solvent is an option for reducing the energy consumed in the regeneration of the carbon capture solvent, because the increase reduces the carbon capture solvent circulation rate.

[0103] “Heat of desorption” refers to the average heat that corresponds to loadings before and after partial desorption of absorbed molecules, such as carbon dioxide.

[0104] “Heat-exchanging” refers to the exchange of heat from one substance to another. Typically, one substance will be at a higher temperature to another substance and material from the warmer substance will be transferred to the other substance.

[0105] “High-heat” refers to a material at a temperature of from 90 to 160°C.

[0106] “Hot” refers to a material at a temperature of from greater than 160 to 220°C. More preferably, the material is at a temperature of from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C.

[0107] “Intensified solvent” refers to a solvent that can achieve a high CO2 loading (optionally > 3.0 mol / L) and forms a greater proportion of bicarbonate salts than carbamate salts. Examples of intensified solvents are included in US 2017 / 0274317 A1 , the disclosure of which is incorporated herein by reference. An intensified solvent, in some embodiments, comprises: an alkanolamine, a reactive amine and a carbonate buffer.

[0108] “Latent heat of vapourisation of water” refers to the water vapourisation occurring at the same time as the CO2 stripping from the carbon capture solvent. The water vapourisation will give heat away in the condenser.

[0109] “Low-heat” refers to a material at a temperature of from 20 to 60 °C. More preferably, the material is at a temperature of from 30 to 55°C.

[0110] “Reboiler” refers to a device that is used to provide heat at the bottom of a regenerator. Typically, the reboiler is used to boil a CC>2 lean solvent produced in a regenerator to generate a hot vapour which in turn is used in the regenerator.

[0111] “Regenerator” refers to a part of a system where heat (typically from vapour) is used to reverse the reaction between the liquid solvent and CO2 to generate CC>2 and a solvent (the solvent being a CO2 lean solvent). Regeneration of a liquid solvent may be partial. A regenerator may be a static column or a Rotary Packed Bed (RPB). “Reflux condensate” refers to a liquid formed when a solvent and / or vapour have undergone condensation. Typically, the solvent and / or vapour are produced in a regenerator.

[0112] “Rotary Packed Bed (RPB)” refers to an absorber or a regenerator where the packing is housed in a rotatable disk (rather than in a static bed, as in a static column), which can be rotated at high speed to generate a high gravity centrifugal force within the RPB.

[0113] “Sensible heat” refers to the difference between the change in temperature in which the carbon capture solvent undergoes during the regeneration process compared to the change in temperature in which the carbon capture solvent undergoes upon maintaining a sufficient minimum temperature approach. The difference in temperature is caused by heat being lost to cooling water in a lean solvent cooler. The temperature difference can be applied with external heat.

[0114] “Solvent” refers to an absorbent. The solvent may be a liquid. The solvent may be an intensified solvent. Optionally, the intensified solvent comprises a tertiary amine, a secondary amine, or a primary amine. Optionally, the intensified solvent may further comprise tertiary amine, a sterically hindered amine, a polyamine, a salt and water. Optionally, the intensified solvent comprises a tertiary amine, a sterically hindered amine, a polyamine, a salt and water. Optionally, the tertiary amine in the intensified solvent is one or more of: N-methyl-diethanolamine (MDEA) or Triethanolamine (TEA). Optionally, the sterically hindered amines in the intensified solvent are one or more of: 2-amino-2- ethyl-1 ,3-propanediol (AEPD), 2-amino-2-hydroxymethyl-1 ,3-propanediol (AHPD) or 2-amino-2- methyl-1 -propanol (AMP). Optionally, the polyamine in the intensified solvent is one or more of: 2- piperazine-1 -ethylamine (AEP) or 1-(2-hydroxyethyl)piperazine. Optionally, the salt in the intensified solvent is potassium carbonate. Optionally, water (for example, deionised water) is included in the solvent so that the solvent exhibits a single liquid phase. Optionally, the solvent is CDRMax® as sold by Carbon Clean Solutions Limited. CDRMax®, as sold by Carbon Clean Solutions Limited, has the following formulation: from 15 to 30 weight % 2-amino-2-methyl propanol (CAS number 124-68-5); from 15 to 30 weight % 1-(2-ethylamino)piperazine (CAS number 140-31-8); from 1 to 3 weight % 2- methylamino-2-methyl propanol (CAS number 27646-80-6); from 0.1 to 1 weight % potassium carbonate (584-529-3); and, the balance being deionised water (CAS number 7732-18-5). Optionally, the solvent is MEA (monoethanolamine).

[0115] “Static column” refers to a part of a system used in a separation method. It is a hollow column with internal mass transfer devices (e.g., trays, structured packing, random packing). A packing bed may be structured or random packing which may contain catalysts or adsorbents.

[0116] “Weight %” refers to the percentage, by total weight, of a particular component within a mixture of components. EXAMPLES

[0117] The following are non-limiting examples that discuss, with reference to tables and figures, the advantages of the present invention. The examples set forth herein are merely examples among other possible examples.

[0118] System 200: A system and method of the present invention

[0119] Figure 2 illustrates a schematic diagram of a system 200 for capturing CO2 from flue gases according to the claimed invention. In the system 200, CO2 is separated from a mixture of gases using a solvent (initially a CO2 lean solvent), which selectively reacts with the CO2 (to form a CO2 rich solvent). After the CO2 has reacted with the solvent (CO2 lean solvent), the solvent (CO2 rich solvent) can be regenerated (to reform CO2 lean solvent) using heat to release the CO2 and regenerate the solvent for further CO2 processing.

[0120] As shown in Figure 2, a flue gas 201 containing CO2 enters the system 200 through flue gas pretreatment system 202. The temperature of the flue gas 201 when entering the system 200 is typically greater than 100°C, typically from 120 to 200°C. The pressure of the flue gas 201 when entering the system 200 is typically at ambient pressure.

[0121] In the flue gas pre-treatment system 202, flue gas 201 undergoes pre-treatment to form flue gas 201 a. The pre-treatment includes cooling and the removal of (some) impurities. For example, in the flue gas pre-treatment system 202, the flue gas 201 is typically cooled to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. Furthermore, any dust, SO2 and NO2 present in the flue gas 201 is removed in the pre-treatment system 202. Typically, the flue gas 201 is cooled through the use of a direct contact cooler. In the direct contact cooler, the flue gas 201 is contacted with a recirculating loop of cool water in a counter-current configuration. Through this contact, the flue gas 201 is cooled to the desired temperature. Typically, any dust, SO2 and NO2 present in the flue gas 201 is removed with an alkali solution.

[0122] The flue gas 201 a optionally passes through a booster fan. The booster fan increases the pressure of flue gas 201 a to compensate for the pressure drop through the system, thereby ensuring that the pressure of the resultant CO2 lean flue gas (called CO2 lean flue gas 201 b in this system) is at the same pressure as flue gas 201 .

[0123] The flue gas 201 a enters the absorber 203, where the flue gas 201 a is contacted with a low-heat, CO2 lean solvent 217g in a counter-current configuration. The low-heat, CC>2 lean solvent 217g is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. The low-heat, CO2 lean solvent 217g enters the absorber 203 via a liquid distributor (not shown in Figure 2) positioned at the top of the absorber 203, and cascades down through the absorber 203. The flue gas 201 a rises through the absorber 203. The absorber 203 contains packing to maximise the surface area to volume ratio. The packing is shown by references 203a, 203b and 203c. Typically, the low-heat, CO2 lean solvent 217g enters the absorber 203 above packing 203b and below packing 203c. The location of the packing and the height of the packing can be optimised on a case-by-case basis. The absorber 203 additionally includes a demister 203d.

[0124] The low-heat, CO2 lean solvent 217g comprises active components which react with the CO2 in the flue gas 201 a. The reaction is exothermic and low temperatures favour the absorption of CO2 into the low-heat, CO2 lean solvent 217g from the flue gas 201 a. To maintain a low temperature, an intercooling section is included between packing 203a and packing 203b. Once the low-heat, CO2 lean solvent 217g has passed through packing 203b, a low-heat, CO2 semi-rich solvent 206a is formed. Typically, the low-heat, CO2 semi-rich solvent 206a is at a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 40 to 60°C. Instead of passing directly down through the absorber 203, the low-heat, CO2 semi-rich solvent 206a passes to an absorber interstage pump 204 to form low-heat, CO2 semirich solvent 206b. The absorber interstage pump 204 is used to feed the low-heat, CO2 semi-rich solvent 206b back into the absorber 203. The low-heat, CO2 semi-rich solvent 206b then passes to an absorber interstage cooler 205 forming low-heat, CO2 semi-rich solvent 206c. The absorber interstage cooler 205 removes any excess heat formed during the exothermic CO2 absorption reaction. In the absorber interstage cooler 205, the low-heat, CO2 semi-rich solvent 206b is typically cooled to a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 35 to 60°C, or, from 40 to 60°C to form the low-heat, CO2 semi-rich solvent 206c. The low-heat, CO2 semi-rich solvent 206c then continues to cascade through absorber 203. Advantageously, by cooling the solvent, the temperature of the solvent is reduced. A solvent with a reduced temperature will be able to have an increased loading of CO2, which in turn reduces the heat of desorption energy required in the regenerator 210.

[0125] When the low-heat, CO2 semi-rich solvent 206c reaches the bottom of the absorber 203, the solvent is rich in CO2 and forms low-heat, CO2 rich solvent 209a. The low-heat, CO2 rich solvent 209a is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C. The low-heat, CO2 rich solvent 209a passes through a CO2 rich solvent pump 207 to form the low-heat, CO2 rich solvent 209b. The low-heat, CO2 rich solvent 209b is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C.

[0126] As the flue gas 201 a passes up through the absorber 203, it is depleted of CO2 and eventually forms CO2 lean flue gas 201 b. When the flue gas 201 a has passed through packing 203b, CO2 lean flue gas 201 b is formed. The CC>2 lean flue gas 201 b passes through a water wash section in packing 203c to recover any water and / or solvent that may be present in the CO2 lean flue gas 201 b. The solvent is removed from the CO2 lean flue gas 201 b by reducing the temperature of the CO2 lean flue gas 201 b to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C by contacting the CO2 lean flue gas 201 b with wash water 221 c. Once the wash water 221 c has cooled the CO2 lean flue gas 201 b, wash water 221 a is formed. Wash water 221 a passes through a water wash pump 219 to form wash water 221 b. The water wash pump 219 provides sufficient pressure to feed the wash water 221 b back into the absorber 203. Wash water 221 b passes through a water wash cooler 220, which cools the wash water 221 b and thereby forming wash water 221 c.

[0127] Once the CO2 lean flue gas 201 b has been washed in the water wash section, the CO2 lean flue gas 201 b continues to pass up through the absorber 203 to be released from the top of the absorber 203. The absorber 203 further includes a demister 203d, through which the CO2 lean flue gas 201 b passes through before leaving the absorber 203. The demister 203d is used to remove liquid droplets from the CO2 lean flue gas 201 b.

[0128] The low-heat, CO2 rich solvent 209b is regenerated in regenerator 210, to reform the low-heat, CO2 lean solvent 217g. The regenerator 210 contains packing to maximise the surface area to volume ratio. The packing is shown by references 210a, 210b and 210c in Figure 2. The packing 210a is present in the half of the regenerator 210 connected to a reboiler 215, this part is the bottom of the regenerator 210. The packing 210c is present in the part of the regenerator 210 connected to a condenser 211 , this part is the top of the regenerator 210. Packing 210b is present between packing 210a and 210c. Packings 210a and 210b are placed in specific locations in the regenerator 210 to maintain the required temperature profile in the regenerator 210. The regenerator 210 is operated at a pressure of from 0.8 to 3.0 bar(g), typically 2.0 bar(g). The regenerator 210 is operated at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C, or, from 130 to 140°C, or, 136°C. Packing 210c is placed in the specified location to wash any vapours present at the top of the regenerator 210 and to recover the solvent and water vapours that have risen to the top of the regenerator 210.

[0129] The low-heat, CO2 rich solvent enters the regenerator 210 via a cross-over heat exchanger 208. The low-heat CO2 rich solvent 209b passes to the cross-over heat exchanger 208. In the cross-over heat exchanger 208, the low-heat, CO2 rich solvent 209b is heated by a high-heat, CO2 lean solvent 217e to form high-heat, CC>2 rich solvent 209c. The high-heat, CC>2 rich solvent 209c is typically at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 113°C.

[0130] The high-heat, CC>2 rich solvent 209c enters the regenerator 210 above packing 210b and cascades down the regenerator 210 to below packing 210a. Inside the regenerator, the high-heat, CO2 rich solvent 209c is heated further through contact with a hot, compressed solvent vapour 217c. Typically, the hot, compressed solvent vapour 217c flows upwards through the regenerator 210, counter-current to the high-heat, CO2 rich solvent 209c. Upon heating, the reaction between the active components of the high-heat, CO2 rich solvent 209c and CO2 reverses, releasing CC>2 gas and forming a high-heat, CO2 semi-lean solvent 217a. The high-heat, CO2 semi-lean solvent 217a is at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 130 to 140°C, or, at 136°C. The CC>2gas and any hot, compressed solvent vapour 217c present at the top of the regenerator 210 form stream 212a. Stream 212a passes to a condenser 211 . Typically, the condenser 211 is a stripper condenser. The condenser 211 forms a condensate 212b from the stream 212a, which passes to a reflux drum 213. The reflux drum 213 separates the condensate 212b into a gaseous CO2 212c and a reflux condensate 212d. The reflux condensate 212d then passes to a reflux pump 214 to form reflux condensate 212e. The reflux pump 214 is used to move the reflux condensate 212e back into the regenerator 210. The reflux condensate 212e then passes back into the regenerator 210 above the packing 210c. Having passed through the condenser 211 , the condensate 212b and the subsequently formed reflux condensate 212d and reflux condensate 212e are typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C.

[0131] The gaseous CO2 212c is the CO2 product stream and can be used in downstream processes.

[0132] The high-heat, CO2 semi-lean solvent 217a is fed into a reboiler 215. Typically, the reboiler 215 is operating at a temperature of 115°C or greater, or at a temperature of 119°C. Typically, the reboiler 215 is operating at a pressure of from 0.2 to 1 bar(g), or at a pressure of 0.7 bar(g). Within the reboiler 215, a first part of the high-heat, CO2 semi-lean solvent 217a is boiled resulting in the formation of a high-heat solvent vapour 217b. The second part of the high-heat, CO2 semi-lean solvent 217a passes out of the reboiler 215 as a high-heat, CC>2 lean solvent 217d. Typically, the high-heat, CC>2 lean solvent 217d is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 217b is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 217b comprises CO2 and water vapour.

[0133] The high-heat solvent vapour 217b passes to a compressor 216, where the high-heat solvent vapour 217b is compressed to form hot, compressed solvent vapour 217c. Typically, the hot, compressed solvent vapour 217c is at a temperature of from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C, or, 195°C and a pressure of from 1 .05 to 3.05 bar(g), typically at 2.05 bar(g).

[0134] The hot, compressed solvent vapour 217c enters the regenerator 210 below packing 210a.

[0135] The high-heat, CC>2 lean solvent 217d passes to a CC>2 lean solvent pump 222 to form high-heat, CO2 lean solvent 217e. Typically, the high-heat, CO2 lean solvent 217e is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. High-heat CC>2 lean solvent 217e passes into the cross-over heat exchanger 208 and is cooled through contact with the low-heat, CO2 rich solvent 209b to form low-heat, CO2 lean solvent 217f. Typically, the low-heat, CO2 lean solvent 217f is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or 45°C. The low-heat, CO2 lean solvent 217f then passes through a CO2 lean solvent cooler 218 to form the low-heat, CO2 lean solvent 217g. The low-heat, CO2 lean solvent 217g is now ready to repeat the absorption process again. Whilst the absorber 203 and regenerator 210 are shown to be columns in Figure 2, in alternative embodiments the absorber 203 and / or regenerator 210 may be a Rotary Packed Bed (RPB).

[0136] Advantageously, by using heat from the hot, compressed solvent vapour 217c in the regenerator 210, heat can be efficiently recovered from the hot, compressed solvent vapour 217c and therefore the amount of energy required by system 200 is reduced compared to conventional carbon capture systems. The full potential of the heat generated by the hot, compressed solvent vapour 217c can be used, which advantageously reduces the steam consumption by the system 200. Thus, the system 200 provides a more energy-efficient system for carbon capture compared to conventional carbon capture systems.

[0137] Further advantageously, a pressure difference between the reboiler 215 and regenerator 210 is used to ensure vaporisation of water in the reboiler 215, thereby increasing the amount of high-heat solvent vapour 217b being generated.

[0138] Further advantageously, a higher pressure in the regenerator 210 is advantageous because this prevents any hot, compressed solvent vapour 217c present at the top of the regenerator 210 from entering the condenser 211 , and instead ensures that any hot, compressed solvent vapour 217c at the top of the regenerator 210 condenses. The heat generated from the condensation can be used in the regenerator 210 to reverse the reaction between the active components of the high-heat, CO2 rich solvent 209c and CO2.

[0139] Further advantageously, a higher pressure in the regenerator 210 compared to the reboiler 215 is advantageous because this reduces the cooling duty of the condenser 211 , thereby providing additional energy savings.

[0140] System 300: A system and method of the present invention

[0141] Figure 3 illustrates a schematic diagram of a system 300 for capturing CO2 from flue gases according to the claimed invention. In the system 300, CO2 is separated from a mixture of gases using a solvent (initially a CO2 lean solvent), which selectively reacts with the CO2 (to form a CO2 rich solvent). After the CO2 has reacted with the solvent (CO2 lean solvent), the solvent (CO2 rich solvent) can be regenerated (to reform CO2 lean solvent) using heat to release the CO2 and regenerate the solvent for further CO2 processing.

[0142] As shown in Figure 3, a flue gas 301 containing CO2 enters the system 300 through flue gas pretreatment system 302. The temperature of the flue gas 301 when entering the system 300 is typically greater than 100°C, typically from 120 to 200°C. The pressure of the flue gas 301 when entering the system 300 is typically at ambient pressure. In the flue gas pre-treatment system 302, flue gas 301 undergoes pre-treatment to form flue gas 301a. The pre-treatment includes cooling and the removal of (some) impurities. For example, in the flue gas pre-treatment system 302, the flue gas 301 is cooled to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. Furthermore, any dust, SO2 and NO2 present in the flue gas 301 is removed in the pre-treatment system 302. Typically, the flue gas 301 is cooled through the use of a direct contact cooler. In the direct contact cooler, the flue gas 301 is contacted with a recirculating loop of cool water In a counter-current configuration. Through this contact, the flue gas 301 is cooled to the desired temperature. Typically, any dust, SO2 and NO2 present in the flue gas 301 is removed with an alkali solution.

[0143] The flue gas 301 a optionally passes through a booster fan. The booster fan increases the pressure of flue gas 301a to compensate for the pressure drop through the system, thereby ensuring that the pressure of the resultant CO2 lean flue gas (called CO2 lean flue gas 301 b in this system) is at the same pressure as flue gas 301 .

[0144] The flue gas 301a enters the absorber 303, where the flue gas 301a is contacted with a low-heat, CO2 lean solvent 317g in a counter-current configuration. The low-heat, CC>2 lean solvent 317g is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. The low-heat, CC>2 lean solvent 317g enters the absorber 303 via a liquid distributor (not shown in Figure 3) positioned at the top of the absorber 303, and cascades down through the absorber 303. The flue gas 301a rises through the absorber 303. The absorber 303 contains packing to maximise the surface area to volume ratio. The packing is shown by references 303a, 303b and 303c. Typically, the low-heat, CC>2 lean solvent 317g enters the absorber 303 above packing 303b and below packing 303c. The location of the packing and the height of the packing can be optimised on a case-by-case basis. The absorber 303 additionally includes a demister 303d.

[0145] The low-heat, CC>2 lean solvent 317g comprises active components which react with the CC>2 in the flue gas 301a. The reaction is exothermic and low temperatures favour the absorption of CO2 into the low-heat, CO2 lean solvent 317g from the flue gas 301a. To maintain a low temperature, an intercooling section is included between packing 303a and packing 303b. Once the low-heat, CO2 lean solvent 317g has passed through packing 303b, a low-heat, CO2 semi-rich solvent 306a is formed. Typically, the low-heat, CO2 semi-rich solvent 306a is at a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 40 to 60°C. Instead of passing directly down through the absorber 303, the low-heat, CO2 semi-rich solvent 306a passes to an absorber interstage pump 304 to form low-heat, CO2 semirich solvent 306b. The absorber interstage pump 304 is used to feed the low-heat, CO2 semi-rich solvent 306b back into the absorber 303. The low-heat, CO2 semi-rich solvent 306b then passes to an absorber interstage cooler 305 forming low-heat, CO2 semi-rich solvent 306c. The absorber interstage cooler 305 removes any excess heat formed during the exothermic CO2 absorption reaction. In the absorber interstage cooler 305, the low-heat, CO2 semi-rich solvent 306b is typically cooled to a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 35 to 60°C, or, from 40 to 60°C to form the low-heat, CO2 semi-rich solvent 306c. The low-heat, CO2 semi-rich solvent 306c then continues to cascade through absorber 303. Advantageously, by cooling the solvent, the temperature of the solvent is reduced. A solvent with a reduced temperature will be able to have an increased loading of CO2, which in turn reduces the heat of desorption energy required in the regenerator 310.

[0146] When the low-heat, CO2 semi-rich solvent 306c reaches the bottom of the absorber 303, the solvent is rich in CC>2 and forms low-heat, CC>2 rich solvent 309a. The low-heat, CC>2 rich solvent 309a is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C. The low-heat, CO2 rich solvent 309a passes through a CO2 rich solvent pump 307 to form the low-heat, CO2 rich solvent 309b. The low-heat, CO2 rich solvent 309b is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C.

[0147] As the flue gas 301 a passes up through the absorber 303, it is depleted of CO2 and eventually forms CC>2 lean flue gas 301 b. When the flue gas 301 a has passed through packing 303b, CC>2 lean flue gas 301 b is formed. The CC>2 lean flue gas 301 b then passes through a water wash section in packing 303c to recover any water and / or solvent that may be present in the CO2 lean flue gas 301 b. The solvent is removed from the CO2 lean flue gas 301 b by reducing the temperature of the CO2 lean flue gas 301 b to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C by contacting the CO2 lean flue gas 301 b with wash water 321 c. Once the wash water 321 c has cooled the CO2 lean flue gas 301 b, wash water 321 a is formed. Wash water 321 a passes through a water wash pump 319 to form wash water 321 b. The water wash pump 319 provides sufficient pressure to feed the wash water 321 b back into the absorber 303. Wash water 321 b passes through a water wash cooler 320, which cools the wash water 321 b and thereby forming wash water 321 c.

[0148] Once the flue gas CO2 lean 301 b has been washed in the water wash section, the CO2 lean flue gas 301 b continues to pass up through the absorber 303 to be released from the top of the absorber 303. The absorber 303 further includes a demister 303d, through which the CO2 lean flue gas 301 b passes through before leaving the absorber 303. The demister 303d is used to remove liquid droplets from the CO2 lean flue gas 301 b.

[0149] The low-heat CC>2 rich solvent 309b is regenerated in regenerator 310, to reform low-heat, CC>2 lean solvent 317g. The regenerator 310 contains packing to maximise the surface area to volume ratio. The packing is shown by references 310a, 310b and 310c in Figure 3. The packing 310a is present in the half of the regenerator 310 connected to a reboiler 315, this part is the bottom of the regenerator 310. The packing 310c is present in the part of the regenerator 310 connected to a condenser 311 , this part is the top of the regenerator 310. Packing 310b is present between packing 310a and 310c. Packings 310a and 310b are placed in specific locations in the regenerator 310 to maintain the required temperature profile in the regenerator 310. The regenerator 310 is operated at a pressure of from 0.8 to 3.0 bar(g), typically 2.0 bar(g). The regenerator 310 is operated at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C, or, from 130 to 140°C, or, 136°C. Packing 310c is placed in the specified location to wash any vapours present in the top of the regenerator 310 and to recover the solvent and water vapours that have risen to the top of the regenerator 310.

[0150] The low-heat CC>2 rich solvent enters the regenerator 310 via a cross-over heat exchanger 308. The low-heat CO2 rich solvent 309b passes to the cross-over heat exchanger 308. In the cross-over heat exchanger 308, the low-heat CC>2 rich solvent 309b is heated by a high-heat, CC>2 lean solvent 317e to form high-heat, CO2 rich solvent 309c. The high-heat, CO2 rich solvent 309c is typically at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 113°C.

[0151] The high-heat, CC>2 rich solvent 309c enters the regenerator 310 above packing 310b and cascades down the regenerator 310 to below packing 310a. Inside the regenerator, the high-heat, CC>2 rich solvent 309c is heated further through contact with a high-heat compressed solvent vapour 318. Typically, the high-heat compressed solvent vapour 318 flows upwards through the regenerator 310, counter-current to the high-heat, CO2 rich solvent 309c. Upon heating, the reaction between the active components of the high-heat, CO2 rich solvent 309c and CO2 reverses, releasing CC>2gas and forming a high-heat, CO2 semi-lean solvent 317a. The high-heat, CO2 semi-lean solvent 317a is at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 130 to 140°C, or, at 136°C.

[0152] The CO2 gas and any high-heat compressed solvent vapour 318 present at the top of the regenerator 310 form stream 312a. Stream 312a passes to a condenser 311 . Typically, the condenser 311 is a stripper condenser. The condenser 311 forms a condensate 312b from the stream 312a, which passes to a reflux drum 313. The reflux drum 313 separates the condensate 312b into a gaseous CO2 312c and a reflux condensate 312d. The reflux condensate 312d then passes to a reflux pump 314 to form reflux condensate 312e. The reflux pump 314 is used to move the reflux condensate 312e back into the regenerator 310. The reflux condensate 312e then passes back into the regenerator 310 above the packing 310c. Having passed through the condenser 311 , the condensate 312b and the subsequently formed reflux condensate 312d and reflux condensate 312e are typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C.

[0153] Prior to passing back into the regenerator 310, a part of reflux condensate 312e is separated off as reflux condensate 312f. Typically, from 5 to 50 weight %, or, from 10 to 40 weight % of the reflux condensate 312e is separated off from the reflux condensate 312e as reflux condensate 312f. The reflux condensate 312f is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C.

[0154] The gaseous CO2 312c is the CO2 product stream and can be used in downstream processes. The high-heat, CO2 semi-lean solvent 317a is fed into a reboiler 315. Typically, the reboiler 315 is operating at a temperature of 115°C or greater, or at 1 19°C. Typically, the reboiler 315 is operating at a pressure of from 0.2 to 1 bar(g), typically at a pressure of 0.7 bar(g). Within the reboiler 315, a first part of the high-heat, CO2 semi-lean solvent 317a is boiled resulting in the formation of a high-heat solvent vapour 317b. A second part of the high-heat, CO2 semi-lean solvent 317a passes out of the reboiler as a high-heat, CC>2 lean solvent 317d. Typically, the high-heat, CC>2 lean solvent 317d is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 317b is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 317b comprises CC>2 and water vapour.

[0155] The high-heat solvent vapour 317b passes to a compressor 316, where the high-heat solvent vapour 317b is compressed to form hot, compressed solvent vapour 317c. Typically, the hot, compressed solvent vapour 317c is at a temperature of from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C, or, 195°C and a pressure of from 1 .05 to 3.05 bar(g), typically at 2.05 bar(g). The hot, compressed solvent vapour 317c is mixed with reflux condensate 312f to form high-heat compressed solvent vapour 318. The high-heat compressed solvent vapour 318 is typically at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or, 139°C.

[0156] The high-heat compressed solvent vapour 318 enters the regenerator 310 below pacing 310a.

[0157] The high-heat, CC>2 lean solvent 317d passes to a CC>2 lean solvent pump 323 to form high-heat, CO2 lean solvent 317e. Typically, the high-heat, CO2 lean solvent 317e is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. High-heat CC>2 lean solvent 317e passes into the cross-over heat exchanger 308 and is cooled through contact with the low-heat CC>2 rich solvent 309b to form low-heat, CC>2 lean solvent 317f. Typically, the low-heat, CC>2 lean solvent 317f is at a temperature of 20 to 60°C, or, from 30 to 55°C, or 45°C. The low-heat, CO2 lean solvent 317f then passes through a CO2 lean solvent cooler 322 to form low-heat, CO2 lean solvent 317g. The low-heat, CO2 lean solvent 317g is now ready to repeat the absorption process again.

[0158] Whilst the absorber 303 and regenerator 310 are shown to be columns in Figure 3, in alternative embodiments the absorber 303 and / or regenerator 310 may be a Rotary Packed Bed (RPB).

[0159] Advantageously, by using heat from the hot, compressed solvent vapour 317c in the regenerator 310, heat can be efficiently recovered from the hot, compressed solvent vapour 317c and therefore the amount of energy required by system 300 is reduced compared to conventional carbon capture systems. The full potential of the heat generated by the high-heat solvent vapour 317c can be used, which advantageously reduces the steam consumption. Thus, system 300 provides a more energyefficient system for carbon capture compared to conventional carbon capture systems. Further advantageously, a pressure difference between the reboiler 315 and regenerator 310 is used to ensure vaporisation of water in the reboiler 315, thereby increasing the amount of high-heat solvent vapour 317b being generated.

[0160] Further advantageously, a higher pressure in the regenerator 310 is advantageous because this prevents any of the high-heat compressed solvent vapour 318 present at the top of the regenerator 310 from entering the condenser 311 , and instead ensures that any of the high-heat compressed solvent vapour 318 at the top of the regenerator 310 condenses. The heat generated from the condensation can be used in the regenerator 310 to reverse the reaction between the active components of the high-heat, CO2 rich solvent 309c and CO2.

[0161] Further advantageously, a higher pressure in the regenerator 310 compared to the reboiler 315 is advantageous because this reduces the cooling duty of the condenser 311 , thereby providing additional energy savings.

[0162] Further advantageously, by combining the hot, compressed solvent vapour 317c with the reflux condensate 312f, the temperature of the vapour / stream entering the regenerator 310 is reduced, which in turn reduces the temperature in the regenerator 310. This advantageously reduces and / or prevents degradation of the solvent due to the very high temperatures prior to combination.

[0163] System 400: A system and method of the present invention

[0164] Figure 4 illustrates a schematic diagram of a system 400 for capturing CO2 from flue gases according to the claimed invention. In the system 400, CO2 is separated from a mixture of gases using a solvent (initially a CO2 lean solvent), which selectively reacts with the CO2 (to form a CO2 rich solvent). After the CO2 has reacted with the solvent (CO2 lean solvent), the solvent (CO2 rich solvent) can be regenerated (to reform CO2 lean solvent) using heat to release the CO2 and regenerate the solvent for further CO2 processing.

[0165] As shown in Figure 4, a flue gas 401 containing CO2 enters the system 400 through flue gas pretreatment system 402. The temperature of the flue gas 401 when entering the system 400 is typically greater than 100°C, typically from 120 to 200°C. The pressure of the flue gas 401 when entering the system 400 is typically at ambient pressure.

[0166] In the flue gas pre-treatment system 402, flue gas 401 undergoes pre-treatment to form flue gas 401 a. The pre-treatment includes cooling and the removal of (some) impurities. For example, in the flue gas pre-treatment system 402, the flue gas 401 is cooled to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. Furthermore, any dust, SO2 and NO2 present in the flue gas 401 is removed in the pre-treatment system 402. Typically, the flue gas 401 is cooled through the use of a direct contact cooler. In the direct contact cooler, the flue gas 401 is contacted with a recirculating loop of cool water in a counter-current configuration. Through this contact, the flue gas 401 is cooled to the desired temperature. Typically, any dust, SO2 and NO2 present in the flue gas 401 is removed with an alkali solution.

[0167] The flue gas 401a optionally passes through a booster fan. The booster fan increases the pressure of the flue gas 401 a to compensate for the pressure drop through the system, thereby ensuring that the pressure of the resultant CO2 lean flue gas (called CO2 lean flue gas 401 b in this system) is at the same pressure as flue gas 401 .

[0168] The flue gas 401a enters the absorber 403, where the flue gas 401a is contacted with a low-heat, CO2 lean solvent 417h in a counter-current configuration. The low-heat, CC>2 lean solvent 417h is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. The low-heat, CO2 lean solvent 417h enters the absorber 403 via a liquid distributor (not shown in Figure 4) positioned at the top of the absorber 403, and cascades down through the absorber 403. The flue gas 401 a rises through the absorber 403. The absorber 403 contains packing to maximise the surface area to volume ratio. The packing is shown by references 403a, 403b and 403c. Typically, the low-heat, CO2 lean solvent 417h enters the absorber 403 above packing 403b and below packing 403c. The location of the packing and the height of the packing can be optimised on a case-by-case basis. The absorber 403 additionally includes a demister 403d.

[0169] The low-heat, CO2 lean solvent 417h comprises active components which react with the CO2 in the flue gas 401a. The reaction is exothermic and low temperatures favour the absorption of CO2 into the low-heat, CO2 lean solvent 417h from the flue gas 401a. To maintain a low temperature, an intercooling section is included between packing 403a and packing 403b. Once the low-heat, CO2 lean solvent 417h has passed through packing 403b, a low-heat, CO2 semi-rich solvent 406a is formed. Typically, the low-heat, CO2 semi-rich solvent 406a is at a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 40 to 60°C. Instead of passing directly down through the absorber 403, the low-heat, CO2 semi-rich solvent 406a passes to an absorber interstage pump 404 to form low-heat, CO2 semirich solvent 406b. The absorber interstage pump 404 is used to feed the low-heat, CO2 semi-rich solvent 406b back into the absorber 403. The low-heat, CO2 semi-rich solvent 406b then passes to an absorber interstage cooler 405 forming low-heat, CO2 semi-rich solvent 406c. The absorber interstage cooler 405 removes any excess heat formed during the exothermic CO2 absorption reaction. In the absorber interstage cooler 405, the low-heat, CO2 semi-rich solvent 406b is typically cooled to a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 35 to 60°C, or, from 40 to 60°C to form the low-heat, CO2 semi-rich solvent 406c. The low-heat, CO2 semi-rich solvent 406c then continues to cascade through absorber 403. Advantageously, by cooling the solvent, the temperature of solvent is reduced. A solvent with a reduced temperature will be able to have an increased loading of CO2, which in turn reduces the heat of desorption energy required in the regenerator 410. When the low-heat, CO2 semi-rich solvent 406c reaches the bottom of the absorber 403, the solvent is rich in CO2 and forms low-heat, CO2 rich solvent 409a. The low-heat, CO2 rich solvent 409a is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C. The low-heat, CO2 rich solvent 409a passes through a CO2 rich solvent pump 407 to form the low-heat, CO2 rich solvent 409b. The low-heat, CO2 rich solvent 409b is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C.

[0170] As the flue gas 401 a passes up through the absorber 403, it is depleted of CO2 and eventually forms CO2 lean flue gas 401 b. When the flue gas 401 a has passed through packing 403b, CO2 lean flue gas 401 b is formed. The CC>2 lean flue gas 401 b then passes through a water wash section in packing 403c to recover any solvent and / or water that may be present in the CO2 lean flue gas 401 b. The solvent is removed from the CO2 lean flue gas 401 b by reducing the temperature of the CO2 lean flue gas 401 b to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C by contacting the CO2 lean flue gas 401 b with wash water 421 c. Once the wash water 421 c has cooled the CO2 lean flue gas 401 b, wash water 421 a is formed. Wash water 421 a passes through a water wash pump 419 to form wash water 421 b. The water wash pump 419 provides sufficient pressure to feed the wash water 421 b back into the absorber 403. Wash water 421 b passes through a water wash cooler 420, which cools the wash water 421 b and thereby forming wash water 421 c.

[0171] Once the CO2 lean flue gas 401 b has been washed in the water wash section, the CO2 lean flue gas 401 b continues to pass up through the absorber 403 to be released from the top of the absorber 403 as CO2 lean flue gas 401 b. The absorber 403 further includes a demister 403d, through which the CO2 lean flue gas 401 b passes through before leaving the absorber 403. The demister 403d is used to remove liquid droplets from the CO2 lean flue gas 401 b.

[0172] The low-heat CC>2 rich solvent 409b is regenerated in regenerator 410, to reform low-heat, CC>2 lean solvent 417h. The regenerator 410 contains packing to maximise the surface area to volume ratio. The packing is shown by references 410a, 410b and 410c in Figure 4. The packing 410a is present in the half of the regenerator 410 connected to a reboiler 415, this part is the bottom of the regenerator 410. The packing 410c is present in the part of the regenerator 410 connected to a condenser 411 , this part is the top of the regenerator 410. Packing 410b is present between packing 410a and 410c. Packings 410a and 410b are placed in specific locations in the regenerator 410 to maintain the required temperature profile in the regenerator 410. The regenerator 410 is operated at a pressure of from 0.8 to 3.0 bar(g), typically 2.0 bar(g). The regenerator 410 is operated at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C, or, from 130 to 140°C, or 136°C. Packing 410c is placed in the specified location to wash any vapours present in the top of the regenerator 410 and to recover the solvent and water vapours that have risen to the top of the regenerator 410. The low-heat CO2 rich solvent enters the regenerator 410 via a cross-over heat exchanger 408. The low-heat CO2 rich solvent 409b passes to the cross-over heat exchanger 408. In the cross-over heat exchanger 408, the low-heat CC>2 rich solvent 409b is heated by a high-heat, CC>2 lean solvent 417f to form high-heat, CO2 rich solvent 409c. The high-heat, CO2 rich solvent 409c is typically at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 113°C.

[0173] The high-heat, CC>2 rich solvent 409c enters the regenerator 410 above packing 410b and cascades down the regenerator 410 to below packing 410a. Inside the regenerator, the high-heat, CO2 rich solvent 409c is heated further through contact with a high-heat compressed solvent vapour 417d and high-heat vapour 412g. Typically, the high-heat compressed solvent vapour 417d and high-heat vapour 412g flow upwards through the regenerator 410, counter-current to the high-heat, CO2 rich solvent 409c. Upon heating, the reaction between the active components of the high-heat, CO2 rich solvent 409c and CO2 reverses, releasing CC>2 gas and forming a high-heat, CO2 semi-lean solvent 417a. The high-heat, CO2 semi-lean solvent 417a is at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 130 to 140°C, or, at 136°C.

[0174] The CC>2gas and any high-heat compressed solvent vapour 417d and / or high-heat vapour 412g present at the top of the regenerator 410 form stream 412a. Stream 412a passes to a condenser 411. Typically, the condenser 411 is a stripper condenser. The condenser 411 forms a condensate 412b from the stream 412a, which passes to a reflux drum 413. The reflux drum 413 separates the condensate 412b into a gaseous CC>2412c and a reflux condensate 412d. The reflux condensate 412d then passes to a reflux pump 414 to form reflux condensate 412e. The reflux pump 414 is used to move the reflux condensate 412e back into the regenerator 410. The reflux condensate 412e then passes back into the regenerator 410 above the packing 410c. Having passed through the condenser 411 , the condensate 412b and the subsequently formed reflux condensate 412d and reflux condensate 412e are typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C.

[0175] Prior to passing back into the regenerator 410, part of reflux condensate 412e is separated off as reflux condensate 412f. Typically, from 5 to 50 weight %, or, from 10 to 40 weight % of the reflux condensate 412e is separated off as reflux condensate 412f. The reflux condensate 412f is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C.

[0176] The gaseous CO2 412c is the CO2 product stream and can be used in downstream processes.

[0177] The high-heat, CO2 semi-lean solvent 417a is fed into a reboiler 415. Typically, the reboiler 415 is operating at a temperature of 115°C or greater, or at 1 19°C. Typically, the reboiler 415 is operating at a pressure of from 0.2 to 1 bar(g), typically at a pressure of 0.7 bar(g). Within the reboiler 415, a first part of the high-heat, CO2 semi-lean solvent 417a is boiled resulting in the formation of a high-heat solvent vapour 417b. A second part of the high-heat, CO2 semi-lean solvent 417a leaves the reboiler as a high-heat, CO2 lean solvent 417e. Typically, the high-heat, CO2 lean solvent 417e is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 417b is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 417b comprises CO2 and water vapour.

[0178] The high-heat solvent vapour 417b passes to a compressor 416, where the high-heat solvent vapour 417b is compressed to form hot, compressed solvent vapour 417c. Typically, the hot, compressed solvent vapour 417c is at a temperature of from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C, or, 193°C and a pressure of from 1 .05 to 3.05 bar(g), typically at 2.05 bar(g). The hot, compressed solvent vapour 417c passes to a reflux condensate heater 422 where it is contacted in a counter-current manner with the reflux condensate 412f to form a high-heat compressed solvent vapour 417d and high-heat vapour 412g. The high-heat compressed solvent vapour 417d is at a temperature of 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or, 137°C. The high-heat vapour 412g is typically at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or, 136°C.

[0179] The high-heat compressed solvent vapour 417d and high-heat vapour 412g enter the regenerator 410 below packing 410a.

[0180] The high-heat, CC>2 lean solvent 417e passes to a CC>2 lean solvent pump 423 to form high-heat, CO2 lean solvent 417f. Typically, the high-heat, CO2 lean solvent 417f is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. High-heat CO2 lean solvent 417f passes into the cross-over heat exchanger 408 and is cooled through contact with the low-heat CO2 rich solvent 409b to form low-heat, CO2 lean solvent 417g. Typically, the low-heat, CO2 lean solvent 417g is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or 45°C. The low-heat, CO2 lean solvent 417g then passes through a CO2 lean solvent cooler 418 to form low-heat, CO2 lean solvent 417h. The low-heat, CO2 lean solvent 417h is now ready to repeat the absorption process again.

[0181] Whilst the absorber 403 and regenerator 410 are shown to be columns in Figure 4, in alternative embodiments the absorber 403 and / or regenerator 410 may be a Rotary Packed Bed (RPB).

[0182] Advantageously, by using heat from the high-heat compressed solvent vapour 417d in the regenerator 410, heat can be efficiently recovered from the high-heat compressed solvent vapour 417c and therefore the amount of energy required by system 400 is reduced compared to conventional carbon capture systems. The full potential of the heat generated by the high-heat solvent vapour 417c can be used, which advantageously reduces the steam consumption. Thus, system 400 provides a more energy-efficient system for carbon capture compared to conventional carbon capture systems. Further advantageously, a pressure difference between the reboiler 415 and regenerator 410 is used to ensure vaporisation of water in the reboiler 415, thereby increasing the amount of high-heat solvent vapour 417b being generated.

[0183] Further advantageously, a higher pressure in the regenerator 410 is advantageous because this prevents any of the high-heat compressed solvent vapour 417d and / or high-heat vapour 412g present at the top of the regenerator 410 from entering the condenser 411 , and instead ensures that the high- heat compressed solvent vapour 417d and high-heat vapour 412g condense. The heat generated from the condensation can then be used in the regenerator 410 to reverse the reaction between the active components of the high-heat, CO2 rich solvent 409c and CO2.

[0184] Further advantageously, a higher pressure in the regenerator 410 compared to the reboiler 415 is advantageous because this reduces the cooling duty of the condenser 411 , thereby providing additional energy savings.

[0185] Further advantageously, by recovering the heat from the hot, compressed solvent vapour 417c by using the reflux condensate 412f, the temperature of the high-heat compressed solvent vapor 417d entering the regenerator 410 is reduced, which in turn reduces the temperature in the regenerator 410. This advantageously reduces and / or prevents degradation of the solvent due to the very high temperatures prior to combination.

[0186] System 500: A system and method of the present invention

[0187] Figure 5 illustrates a schematic diagram of a system 500 for capturing CO2 from flue gases according to the claimed invention. In the system 500, CO2 is separated from a mixture of gases using a solvent (initially a CO2 lean solvent), which selectively reacts with the CO2 (to form a CO2 rich solvent). After the CO2 has reacted with the solvent (CO2 lean solvent), the solvent (CO2 rich solvent) can be regenerated (to reform CO2 lean solvent) using heat to release the CO2 and regenerate the solvent for further CO2 processing.

[0188] As shown in Figure 5, a flue gas 501 containing CO2 enters the system 500 through flue gas pretreatment system 502. The temperature of the flue gas 501 when entering the system 500 is typically greater than 100°C, typically from 120 to 200°C. The pressure of the flue gas 501 when entering the system 500 is typically at ambient pressure.

[0189] In the flue gas pre-treatment system 502, the flue gas 501 undergoes pre-treatment to form flue gas 501 a. The pre-treatment includes cooling and the removal of (some) impurities. For example, in the flue gas pre-treatment system 502, the flue gas 501 is cooled to a temperature of 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. Furthermore, any dust, SO2 and NO2 present in the flue gas 501 is removed in the pre-treatment system 502. Typically, the flue gas 501 is cooled through the use of a direct contact cooler. In the direct contact cooler, the flue gas 501 is contacted with a recirculating loop of cool water in a counter-current configuration. Through this contact, the flue gas 501 is cooled to the desired temperature. Typically, any dust, SO2 and NO2 present in the flue gas 501 is removed with an alkali solution.

[0190] The flue gas 501 a optionally passes through a booster fan. The booster fan increases the pressure of the flue gas 501 a to compensate for the pressure drop through the system, thereby ensuring that the pressure of the resultant CO2 lean flue gas (called CO2 lean flue gas 501 b in this system) is at the same pressure as flue gas 501 .

[0191] The flue gas 501 a enters the absorber 503, where the flue gas 501 a is contacted with a low-heat, CO2 lean solvent 517h in a counter-current configuration. The low-heat, CC>2 lean solvent 517h is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. The low-heat, CC>2 lean solvent 517h enters the absorber 503 via a liquid distributor (not shown in Figure 5) positioned at the top of the absorber 503, and cascades down through the absorber 503. The flue gas 501 a rises through the absorber 503. The absorber 503 contains packing to maximise the surface area to volume ratio. The packing is shown by references 503a, 503b and 503c. Typically, the low-heat, CC>2 lean solvent 517h enters the absorber 503 above packing 503b and below packing 503c. The location of the packing and the height of the packing can be optimised on a case-by-case basis. The absorber 503 additionally includes a demister 503d.

[0192] The low-heat, CO2 lean solvent 517h comprises active components which react with the CO2 in the flue gas 501 a. The reaction is exothermic and low temperatures favour the absorption of CO2 into the low-heat, CO2 lean solvent 517h from the flue gas 501 a. To maintain a low temperature, an intercooling section is included between packing 503a and packing 503b. Once the low-heat, CO2 lean solvent 517h has passed through packing 503b, a low-heat, CO2 semi-rich solvent 506a is formed. Typically, the low-heat, CO2 semi-rich solvent 506a is at a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 40 to 60°C. Instead of passing directly down through the absorber 503, the low-heat, CO2 semi-rich solvent 506a passes to an absorber interstage pump 504 to form low-heat, CO2 semirich solvent 506b. The absorber interstage pump 504 is used to feed the low-heat, CO2 semi-rich solvent 506b back into the absorber 503. The low-heat, CO2 semi-rich solvent 506b then passes to an absorber interstage cooler 505 forming low-heat, CO2 semi-rich solvent 506c. The absorber interstage cooler 505 removes any excess heat formed during the exothermic CO2 absorption reaction. In the absorber interstage cooler 505, the low-heat, CO2 semi-rich solvent 506b is typically cooled to a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 35 to 60°C, or, from 40 to 60°C to form the low-heat, CO2 semi-rich solvent 506c. The low-heat, CO2 semi-rich solvent 506c then continues to cascade through absorber 503. Advantageously, by cooling the solvent, the temperature of the solvent is reduced. A solvent with a reduced temperature will have an increased loading of CO2, which in turn reduces the heat of desorption energy required in the regenerator 510. When the low-heat, CO2 semi-rich solvent 506c reaches the bottom of the absorber 503, the solvent is rich in CO2 and forms low-heat, CO2 rich solvent 509a. The low-heat, CO2 rich solvent 509a is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C. The low-heat, CO2 rich solvent 509a passes through a CO2 rich solvent pump 507 to form low- heat, CC>2 rich solvent 509b. The low-heat, CC>2 rich solvent 509b is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C. The low-heat, CO2 rich solvent 509b is then split into two, to form low-heat, CO2 rich solvent 509c and low-heat, CO2 rich solvent 509d. Typically, from 1 to 20 weight %, or, from 5 to 15 weight % of the low-heat, CO2 rich solvent 509b forms the low-heat, CO2 rich solvent 509d. Typically, from 80 to 99 weight %, or, from 95 to 85 weight % of the low-heat, CO2 rich solvent 509b forms the low-heat, CO2 rich solvent 509c. The temperature of the low-heat, CC>2 rich solvent 509c and of the low-heat, CC>2 rich solvent 509d is from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 50°C, or, from 30 to 45°C, or, from 35 to 45°C, or, 40°C.

[0193] As the flue gas 501 a passes up through the absorber 503, it is depleted of CO2 and eventually forms CC>2 lean flue gas 501 b. When the flue gas 501 a has passed through packing 503b, CC>2 lean flue gas 501 b is formed. The CC>2 lean flue gas 501 b passes through a water wash section in packing 503c to recover any solvent and / or water that may be present in the CC>2 lean flue gas 501 b. The solvent is removed from the CO2 lean flue gas 501 b by reducing the temperature of the CO2 lean flue gas 501 b to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C by contacting the CO2 lean flue gas 501 b with wash water 521 c. Once the wash water 521 c has cooled the CO2 lean flue gas 501 b, wash water 521 a is formed. Wash water 521 a passes through a water wash pump 519 to form wash water 521 b. The water wash pump 519 provides sufficient pressure to feed the wash water 521 b back into the absorber 503. Wash water 521 b passes through a water wash cooler 520, which cools the wash water 521 b and thereby forming wash water 521 c.

[0194] Once the CO2 lean flue gas 501 b has been washed in the water wash section, the CO2 lean flue gas 501 b continues to pass up through the absorber 503 to be released from the top of the absorber 503. The absorber 503 further includes a demister 503d, through which the CO2 lean flue gas 501 b passes through before leaving the absorber 503. The demister 503d is used to remove liquid droplets from the CO2 lean flue gas 501 b.

[0195] The low-heat, CO2 rich solvent 509c is regenerated in regenerator 510, to reform low-heat, CO2 lean solvent 517h. The regenerator 510 contains packing to maximise the surface area to volume ratio. The packing is shown by references 510a, 510b and 510c in Figure 5. The packing 510a is present in the half of the regenerator 510 connected to a reboiler 515, this part is the bottom of the regenerator 510. The packing 510c is present in the part of the regenerator 510 connected to a condenser 511 , this part is the top of the regenerator 510. Packing 510b is present between packing 510a and 510c. Packings 510a and 510b are placed in specific locations in the regenerator 510 to maintain the required temperature profile in the regenerator 510. The regenerator 510 is operated at a pressure of from 0.8 to 3.0 bar(g), typically 2.0 bar(g). The regenerator 510 is operated at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C, or, from 130 to 140°C, or, 136°C. Packing 510c is placed in the specified location to wash any vapours present in the top of the regenerator 510 and to recover the solvent and water vapours that have risen to the top of the regenerator 510.

[0196] The low-heat, CO2 rich solvent enters the regenerator 510 via a cross-over heat exchanger 508. The low-heat CO2 rich solvent 509c passes to the cross-over heat exchanger 508. In the cross-over heat exchanger 508, the low-heat, CO2 rich solvent 509c is heated by a high-heat, CC>2 lean solvent 517f to form high-heat, CO2 rich solvent 509e. The high-heat, CO2 rich solvent 509e is typically at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 113°C.

[0197] The high-heat, CC>2 rich solvent 509e enters the regenerator 510 above packing 510b and cascades down the regenerator 510 to below packing 510a. Inside the regenerator, the high-heat, CC>2 rich solvent 509e is heated further through contact with a high-heat compressed solvent vapour 517d. Typically, the high-heat compressed solvent vapour 517d flows upwards through the regenerator 510, counter-current to the high-heat, CO2 rich solvent 509e. Upon heating, the reaction between the active components of the high-heat, CO2 rich solvent 509e and CO2 reverses, releasing CC>2 gas and forming a high-heat, CO2 semi- lean solvent 517a. The high-heat, CO2 semi-lean solvent 517a is at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 130 to 140°C, or, from 135 to 145°C, or, at 136°C.

[0198] The CO2 gas and any high-heat compressed solvent vapour 517d present at the top of the regenerator 510 form stream 512a. Stream 512a passes to a condenser 511 . Typically, the condenser 511 is a stripper condenser. The condenser 511 forms a condensate 512b from the stream 512a, which passes to a reflux drum 513. The reflux drum 513 separates the condensate 512b to form a gaseous CC>2512c and a reflux condensate 512d. The reflux condensate 512d then passes to a reflux pump 514 to form reflux condensate 512e. The reflux pump 514 is used to move the reflux condensate 512e back into the regenerator 510. The reflux condensate 512e then passes back into the regenerator 510 above the packing 510c. Having passed through the condenser 511 , the condensate 512b and the subsequently formed reflux condensate 512d and reflux condensate 512e are typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C.

[0199] The gaseous CO2 512c is the CO2 product stream and can be used in downstream processes.

[0200] The high-heat, CO2 semi-lean solvent 517a is fed into a reboiler 515. Typically, the reboiler 515 is operating at a temperature of 115°C or greater, or at 1 19°C. Typically, the reboiler 515 is operating at a pressure of from 0.2 to 1 bar(g), typically at a pressure of 0.7 bar(g). Within the reboiler 515, a first part of the high-heat, CO2 semi-lean solvent 517a is boiled resulting in the formation of a high-heat solvent vapour 517b. A second part of the high-heat, CO2 semi-lean solvent 517a leaves the reboiler 515 as a high-heat, CO2 lean solvent 517e. Typically, the high-heat, CO2 lean solvent 517e is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 517b is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 517b comprises CO2 and water vapour.

[0201] The high-heat solvent vapour 517b passes to a compressor 516, where the high-heat solvent vapour 517b is compressed to form hot, compressed solvent vapour 517c. Typically, the hot, compressed solvent vapour 517c is at a temperature of from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C, or, 193°C and a pressure of from 1 .05 to 3.05 bar(g), typically at 2.05 bar(g). The hot, compressed solvent vapour 517c passes to a CC>2 rich solvent preheater 522 where it is contacted in a counter-current manner with the low-heat, CO2 rich solvent 509d. Upon contact, the hot, compressed solvent vapour 517c is cooled to form a high-heat compressed solvent vapour 517d and a high-heat, CC>2 rich solvent 509f. The high-heat compressed solvent vapour 517d is at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or, 137°C. The high-heat, CO2 rich solvent 509f is at a temperature of from 90 to 160°C, or, from 125 to 155°C, or, from 125 to 145°C, or, from 125 to 130°C, or, 126°C.

[0202] The high-heat, CC>2 rich solvent 509f enters the regenerator 510 above packing 510a and passes out of the regenerator as high-heat, CO2 semi-lean solvent 517a.

[0203] The high-heat compressed solvent vapour 517d passes into the regenerator 510 below packing 510a.

[0204] The high-heat, CC>2 lean solvent 517e passes to a CC>2 lean solvent pump 523 to form high-heat, CO2 lean solvent 517f. The high-heat CC>2 lean solvent 517f is at a temperature of 90 to 160°C, or, from 100 to 120°C, or, 119°C. High-heat CO2 lean solvent 517f passes into the cross-over heat exchanger 508 and is cooled through contact with the low-heat, CO2 rich solvent 509c to form low-heat, CO2 lean solvent 517g. Typically, the low-heat, CC>2 lean solvent 517g is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or 48°C. The low-heat, CO2 lean solvent 517g then passes through a CO2 lean solvent cooler 518 to form low-heat, CO2 lean solvent 517h. The low-heat, CO2 lean solvent 517h is now ready to repeat the absorption process again.

[0205] Whilst the absorber 503 and regenerator 510 are shown to be columns in Figure 5, in alternative embodiments the absorber 503 and / or regenerator 510 may be a Rotary Packed Bed (RPB).

[0206] Advantageously, by using heat from the high-heat compressed solvent vapour 517d in the regenerator 510, heat can be efficiently recovered from the high-heat compressed solvent vapour 517c and therefore the amount of energy required by system 500 is reduced compared to conventional carbon capture systems. The full potential of the heat generated by the high-heat solvent vapour 517c can be used, which advantageously reduces the steam consumption. Thus, system 500 provides a more energy-efficient system for carbon capture compared to conventional carbon capture systems.

[0207] Further advantageously, a pressure difference between the reboiler 515 and regenerator 510 is used to ensure vaporisation of water in the reboiler 515, thereby increasing the amount of high-heat solvent vapour 517b being generated.

[0208] Further advantageously, a high pressure in the regenerator 510 is advantageous because this prevents any of the high-heat compressed solvent vapour 517d present at the top of the regenerator 510 from entering the condenser 511 , and instead ensures that the high-heat, compressed solvent vapour 517d condenses. The heat generated by the condensation can then be used in the regenerator 510 to reverse the reaction between the active components of the high-heat, CO2 rich solvent 509e and CO2.

[0209] Further advantageously, a higher pressure in the regenerator 510 compared to the reboiler 515 is advantageous because this reduces the cooling duty of the condenser 511 , thereby providing additional energy savings.

[0210] Further advantageously, by recovering the heat from the hot, compressed solvent vapour 517c by using the low-heat, CC>2 rich solvent 509d, the temperature of the high-heat compressed solvent vapour 517d entering the regenerator 510 is reduced, which in turn reduces the temperature in the regenerator 510. This advantageously reduces and / or prevents degradation of the solvent due to the very high temperatures prior to combination.

[0211] System 600: A system and method of the present invention

[0212] Figure 6 illustrates a schematic diagram of a system 600 for capturing CO2 from flue gases according to the claimed invention. In the system 600, CO2 is separated from a mixture of gases using a solvent (initially a CO2 lean solvent), which selectively reacts with the CO2 (to form a CO2 rich solvent). After the CO2 has reacted with the solvent (CO2 lean solvent), the solvent (CO2 rich solvent) can be regenerated (to reform CO2 lean solvent) using heat to release the CO2 and regenerate the solvent for further CO2 processing.

[0213] As shown in Figure 6, a flue gas 601 containing CO2 enters the system 600 through flue gas pretreatment system 602. The temperature of the flue gas 601 when entering the system 600 is typically greater than 100°C, typically from 120 to 200°C. The pressure of the flue gas 601 when entering the system 600 is typically at ambient pressure.

[0214] In the flue gas pre-treatment system 602, flue gas 601 undergoes pre-treatment to form flue gas 601 a. The pre-treatment includes cooling and the removal of (some) impurities. For example, in the flue gas pre-treatment system 602, the flue gas 601 is cooled to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. Furthermore, any dust, SO2 and NO2 present in the flue gas 601 is removed in the pre-treatment system 602. Typically, the flue gas 601 is cooled through the use of a direct contact cooler. In the direct contact cooler, the flue gas 601 is contacted with a recirculating loop of cool water in a counter-current configuration. Through this contact, the flue gas 601 is cooled to the desired temperature. Typically, any dust, SO2 and NO2 present in the flue gas 601 is removed with an alkali solution.

[0215] The flue gas 601 a optionally passes through a booster fan. The booster fan increases the pressure of flue gas 601a to compensate for the pressure drop through the system, thereby ensuring that the pressure of the resultant CO2 lean flue gas (called CO2 lean flue gas 601 b in this system) is at the same pressure as flue gas 601 .

[0216] The flue gas 601a enters the absorber 603, where the flue gas 601a is contacted with a low-heat, CO2 lean solvent 617h in a counter-current configuration. The low-heat, CC>2 lean solvent 617h is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. The low-heat, CO2 lean solvent 617h enters the absorber 603 via a liquid distributor (not shown in Figure 6) positioned at the top of the absorber 603, and cascades down through the absorber 603. The flue gas 601 a rises through the absorber 603. The absorber 603 contains packing to maximise the surface area to volume ratio. The packing is shown by references 603a, 603b and 603c. Typically, the low-heat, CO2 lean solvent 617h enters the absorber 603 above packing 603b and below packing 603c. The location of the packing and the height of the packing can be optimised on a case-by-case basis. The absorber 603 additionally includes a demister 603d.

[0217] The low-heat, CC>2 lean solvent 617h comprises active components which react with the CC>2 in the flue gas 601a. The reaction is exothermic and low temperatures favour the absorption of CO2 into the low-heat, CO2 lean solvent 617h from the flue gas 601a. To maintain a low temperature, an intercooling section is included between packing 603a and packing 603b. Once the low-heat, CO2 lean solvent 617h has passed through packing 603b, a low-heat, CO2 semi-rich solvent 606a is formed. Typically, the low-heat, CO2 semi-rich solvent 606a is at a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 40 to 60°C Instead of passing directly down through the absorber 603, the low-heat, CO2 semi-rich solvent 606a passes to an absorber interstage pump 604 to form low-heat, CO2 semirich solvent 606b. The absorber interstage pump 604 is used to feed the low-heat, CO2 semi-rich solvent 606b back into the absorber 603. The low-heat, CO2 semi-rich solvent 606b then passes to an absorber interstage cooler 605 forming low-heat, CO2 semi-rich solvent 606c. The absorber interstage cooler 605 removes any excess heat formed during the exothermic CO2 absorption reaction. In the absorber interstage cooler 605, the low-heat, CO2 semi-rich solvent 606b is typically cooled to a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 35 to 60°C, or, from 40 to 60°C to form the low-heat, CO2 semi-rich solvent 606c. The low-heat, CO2 semi-rich solvent 606c then continues to cascade through absorber 603. Advantageously, by cooling the solvent, the temperature of the solvent is reduced. A solvent with a reduced temperature will have an increased loading of CO2, which in turn reduces the heat of desorption energy required in the regenerator 610.

[0218] As the flue gas 601 a passes up through the absorber 603, it is depleted of CO2 and eventually forms CO2 lean flue gas 601 b. When the flue gas 601 a has passed through packing 603b, CO2 lean flue gas 601 b is formed. The CC>2 lean flue gas 601 b passes through a water wash section in packing 603c to recover any solvent and / or water that may be present in the CC>2 lean flue gas 601 b. The solvent is removed from the CO2 lean flue gas 601 b by reducing the temperature of the CO2 lean flue gas 601 b to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C by contacting the CO2 lean flue gas 601 b with wash water 621 c. Once the wash water 621 c has cooled the CO2 lean flue gas 601 b, wash water 621 a is formed. Wash water 621 a passes through a water wash pump 619 to form wash water 621 b. The water wash pump 619 provides sufficient pressure to feed the wash water 621 b back into the absorber 603. Wash water 621 b passes through a water wash cooler 620, which cools the wash water 621 b and thereby forming wash water 621 c.

[0219] Once the CO2 lean flue gas 601 b has been washed in the water wash section, the CO2 lean flue gas 601 b continues to pass up through the absorber 603 to be released from the top of the absorber 603. The absorber 603 further includes a demister 603d, through which the CO2 lean flue gas 601 b passes through before leaving the absorber 603. The demister 603d is used to remove liquid droplets from the CO2 lean flue gas 601 b.

[0220] When the low-heat, CO2 semi-rich solvent 606c reaches the bottom of the absorber 603, the solvent is rich in CO2 and forms low-heat, CO2 rich solvent 609a. The low-heat, CO2 rich solvent 609a is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C. The low-heat, CO2 rich solvent 609a passes through a CO2 rich solvent pump 607 to form low- heat, CC>2 rich solvent 609b. The low-heat, CC>2 rich solvent 609b is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C.

[0221] The low-heat, CO2 rich solvent 609b is regenerated in regenerator 610, to reform low-heat, CO2 lean solvent 617h. The regenerator 610 contains packing to maximise the surface area to volume ratio. The packing is shown by references 610a, 610b and 610c in Figure 6. The packing 610a is present in the half of the regenerator 610 connected to a reboiler 615, this part is the bottom of the regenerator 610. The packing 610c is present in the part of the regenerator 610 connected to a condenser 611 , this part is the top of the regenerator 610. Packing 610b is present between packing 610a and 610c. Packings 610a and 610b are placed in specific locations in the regenerator 610 to maintain the required temperature profile in the regenerator 610. The regenerator 610 is operated at a pressure of from 0.8 to 3.0 bar(g), or at 2.0 bar(g). The regenerator 610 is operated at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C, or, from 130 to 140°C, or, 136°C. Packing 610c is placed in the specified location to wash any vapours present in the top of the regenerator 610 and to recover the solvent and water vapours that have risen to the top of the regenerator 610.

[0222] The low-heat, CO2 rich solvent enters the regenerator 610 via a cross-over heat exchanger 608. The low-heat CO2 rich solvent 609b passes to the cross-over heat exchanger 608. In the cross-over heat exchanger 608, the low-heat, CO2 rich solvent 609b is heated by a high-heat, CC>2 lean solvent 617f to form high-heat, CO2 rich solvent 609c. The high-heat, CO2 rich solvent 609c is typically at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 113°C.

[0223] The high-heat, CO2 rich solvent 609c enters the regenerator 610 above packing 610b and cascades down the regenerator 610 to below packing 610a. Inside the regenerator, the high-heat, CC>2 rich solvent 609c is heated further through contact with a high-heat compressed solvent vapour 617d. Typically, the high-heat compressed solvent vapour 617d flows upwards through the regenerator 610, counter-current to the high-heat, CO2 rich solvent 609c. Upon heating, the reaction between the active components of the high-heat, CO2 rich solvent 609c and CO2 reverses, releasing CC>2gas and forming a high-heat, CO2 semi-lean solvent 617a. The high-heat, CO2 semi-lean solvent 617a is at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 130 to 140°C, or, at 136°C.

[0224] The CO2 gas and any high-heat compressed solvent vapour 617d present at the top of the regenerator 610 form stream 612a. Stream 612a passes to a condenser 611 . Typically, the condenser 611 is a stripper condenser. The condenser 611 forms a condensate 612b from the stream 612a, which passes to a reflux drum 613. The reflux drum 613 separates the condensate 612b into a gaseous CO26I2C and a reflux condensate 612d. The reflux condensate 612d then passes to a reflux pump 614 to form reflux condensate 612e. The reflux pump 614 is used to move the reflux condensate 612e back into the regenerator 610. The reflux condensate 612e then passes back into the regenerator 610 above the packing 610c. Having passed through the condenser 611 , the condensate 612b and the subsequently formed reflux condensate 612d and reflux condensate 612e are typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C.

[0225] The gaseous CO2 612c is the CO2 product stream and can be used in downstream processes.

[0226] Reflux condensate 612e enters the regenerator 610 above packing 610c and is heated to form preheated reflux condensate 623a. Typically, the preheated reflux condensate 623a is at a temperature of from 90 to 120°C, or, from 100 to 110°C, or, 105°C. The preheated reflux condensate 623a is withdrawn from the regenerator 610 from between the packings 610b and 610c and passes through a preheated reflux condensate pump 624 to form preheated reflux condensate 623b. Typically, the preheated reflux condensate 623b is at a temperature of from 90 to 120°C, or, from 100 to 1 10°C, or, 105°C. The preheated reflux condensate 623b passes to a reflux condensate vaporiser 622. The high-heat, CO2 semi-lean solvent 617a is fed into a reboiler 615. Typically, the reboiler 615 is operating at a temperature of 115°C or greater, or at 119°C. Typically, the reboiler 615 is operating at a pressure of from 0.2 to 1 bar(g), or at of 0.7 bar(g). Within the reboiler 615, a first part of the high- heat, CO2 semi-lean solvent 617a is boiled resulting in the formation of a high-heat solvent vapour 617b. A second part of the high-heat, CO2 semi-lean solvent 617a leaves the reboiler 615 as a high- heat, CO2 lean solvent 617e. Typically, the high-heat, CO2 lean solvent 617e is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 617b is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 617b comprises CO2 and water vapour.

[0227] The high-heat solvent vapour 617b passes to a compressor 616, where the high-heat solvent vapour 617b is compressed to form hot, compressed solvent vapour 617c. Typically, the hot, compressed solvent vapour 617c is at a temperature of from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C, or, 193°C and a pressure of from 1 .05 to 3.05 bar(g), or at 2.05 bar(g). The hot, compressed solvent vapour 617c passes to the reflux condensate vaporiser 622 where it is contacted in a counter-current manner with the preheated reflux condensate 623b. The reflux condensate 623b is typically at a temperature of from 90 to 120°C, or, from 100 to 110°C, or, 105°C. The preheated reflux condensate 623b cools the hot, compressed solvent vapour 617c to form high-heat preheated reflux condensate vapour 623c and a high-heat compressed solvent vapour 617d. The high-heat compressed solvent vapour 617d is at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or, 137°C. The high-heat preheated reflux condensate vapour 623c is at a temperature of from 125 to 140°C, or, from 130 to 155°C, or, from 135 to 145°C, or 136°C.

[0228] The high-heat preheated reflux condensate vapour 623c and high-heat compressed solvent vapour 617d enter the regenerator 610 below packing 610a.

[0229] The high-heat, CC>2 lean solvent 617e passes to a CC>2 lean solvent pump 625 to form high-heat, CO2 lean solvent 617f. Typically, the high-heat, CO2 lean solvent 617f is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. High-heat CO2 lean solvent 617f passes into the cross-over heat exchanger 608 and is cooled through contact with the low-heat, CO2 rich solvent 609b to form low-heat, CO2 lean solvent 617g. Typically, the low-heat, CO2 lean solvent 617g is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or 45°C. The low-heat, CO2 lean solvent 617g then passes through a CO2 lean solvent cooler 618 to form low-heat, CO2 lean solvent 617h. The low-heat, CO2 lean solvent 617h is now ready to repeat the absorption process again.

[0230] Whilst the absorber 603 and regenerator 610 are shown to be columns in Figure 6, in alternative embodiments the absorber 603 and / or regenerator 610 may be a Rotary Packed Bed (RPB). Advantageously, by using heat from the high-heat compressed solvent vapour 617d in the regenerator 610, heat can be efficiently recovered from the high-heat solvent vapour 617c and therefore the amount of energy required by system 600 is reduced compared to conventional carbon capture systems. The full potential of the heat generated by the high-heat solvent vapour 617c can be used, which advantageously reduces the steam consumption. Thus, system 600 provides a more energy-efficient system for carbon capture compared to conventional carbon capture systems.

[0231] Further advantageously, a pressure difference between the reboiler 615 and regenerator 610 is used to ensure vaporisation of water in the reboiler 615, thereby increasing the amount of high-heat solvent vapour 617b being generated.

[0232] Further advantageously, a high pressure in the regenerator 610 is advantageous because this prevents any of the high-heat compressed solvent vapour 617d and high-heat preheated reflux condensate vapour 623c present at the top of the regenerator 610 from entering the condenser 611 , and instead ensures that the high-heat compressed solvent vapour 617d and high-heat preheated reflux condensate vapour 623c condenses. The heat generated by the condensation can then be used in the regenerator 610 to reverse the reaction between the active components of the high-heat, CO2 rich solvent 609c and CO2.

[0233] Further advantageously, a higher pressure in the regenerator 610 compared to the reboiler 615 is advantageous because this reduces the cooling duty of the condenser 611 , thereby providing additional energy savings.

[0234] Further advantageously, by recovering heat from the hot, compressed solvent vapour 617c by using the preheated reflux condensate 623b, the temperature of the high-heat compressed solvent vapour 617d entering the regenerator 610 is reduced, which in turn reduces the temperature in the regenerator 610. This advantageously reduces and / or prevents degradation of the solvent due to the very high temperatures prior to combination.

[0235] Further advantageously, by using the preheated reflux condensate 623b, more of the preheated reflux condensate 612e can be vapourised by using heat from the hot compressed solvent vapour 617c (thus reducing the amount of external steam required by the system and reducing the condenser 611 duty) In summary, through using heat from the hot, compressed solvent vapour 617c, better use of the heat in the regenerator 610 results.

[0236] System 700: A system and method of the present invention

[0237] Figure 7 illustrates a schematic diagram of a system 700 for capturing CO2 from flue gases according to the claimed invention. In the system 700, CO2 is separated from a mixture of gases using a solvent (initially a CO2 lean solvent), which selectively reacts with the CO2 (to form a CO2 rich solvent). After the CO2 has reacted with the solvent (CO2 lean solvent), the solvent (CO2 rich solvent) can be regenerated (to reform CO2 lean solvent) using heat to release the CO2 and regenerate the solvent for further CO2 processing.

[0238] As shown in Figure 7, a flue gas 701 containing CO2 enters the system 700 through flue gas pretreatment system 702. The temperature of the flue gas 701 when entering the system 700 is typically greater than 100°C, typically from 120 to 200°C. The pressure of the flue gas 701 when entering the system 700 is typically at ambient pressure.

[0239] In the flue gas pre-treatment system 702, flue gas 701 undergoes pre-treatment to form flue gas 701 a. The pre-treatment includes cooling and the removal of (some) impurities. For example, in the flue gas pre-treatment system 702, the flue gas 701 is cooled to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. Furthermore, any dust, SO2 and NO2 present in the flue gas 701 is removed in the pre-treatment system 702. Typically, the flue gas 701 is cooled through the use of a direct contact cooler. In the direct contact cooler, the flue gas 701 is contacted with a recirculating loop of cool water in a counter-current configuration. Through this contact, the flue gas 701 is cooled to the desired temperature. Typically, any dust, SO2 and NO2 present in the flue gas 701 is removed with an alkali solution.

[0240] The flue gas 701 a optionally passes through a booster fan. The booster fan increases the pressure of flue gas 701 a to compensate for the pressure drop through the system, thereby ensuring that the pressure of the resultant CO2 lean flue gas (called CO2 lean flue gas 701 b in this system) is at the same pressure as flue gas 701 .

[0241] The flue gas 701 a enters the absorber 703, where the flue gas 701 a is contacted with a low-heat, CO2 lean solvent 717h in a counter-current configuration. The low-heat, CC>2 lean solvent 717h is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. The low-heat, CC>2 lean solvent 717h enters the absorber 703 via a liquid distributor (not shown in Figure 7) positioned at the top of the absorber 703, and cascades down through the absorber 703. The flue gas 701 a rises through the absorber 703. The absorber 703 contains packing to maximise the surface area to volume ratio. The packing is shown by references 703a, 703b and 703c. Typically, the low-heat, CC>2 lean solvent 717h enters the absorber 703 above packing 703b and below packing 703c. The location of the packing and the height of the packing can be optimised on a case-by-case basis. The absorber 703 additionally includes a demister 703d.

[0242] The low-heat, CC>2 lean solvent 717h comprises active components which react with the CC>2 in the flue gas 701 a. The reaction is exothermic and low temperatures favour the absorption of CO2 into the low-heat, CO2 lean solvent 717h from the flue gas 701 a. To maintain a low temperature, an intercooling section is included between packing 703a and packing 703b. Once the low-heat, CO2 lean solvent 717h has passed through packing 703b, a low-heat, CO2 semi-rich solvent 706a is formed. Typically, the low-heat, CO2 semi-rich solvent 706a is at a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 40 to 60°C. Instead of passing directly down through the absorber 703, the low-heat, CO2 semi-rich solvent 706a passes to an absorber interstage pump 704 to form low-heat, CO2 semirich solvent 706b. The absorber interstage pump 704 is used to feed the low-heat, CO2 semi-rich solvent 706b back into the absorber 703. The low-heat, CO2 semi-rich solvent 706b then passes to an absorber interstage cooler 705 forming low-heat, CO2 semi-rich solvent 706c. The absorber interstage cooler 705 removes any excess heat formed during the exothermic CO2 absorption reaction. In the absorber interstage cooler 705, the low-heat, CO2 semi-rich solvent 706b is typically cooled to a temperature of from 20 to 60°C, or, from 30 to 60°C, or, from 35 to 60°C, or, from 40 to 60°C to form the low-heat, CO2 semi-rich solvent 706c. The low-heat, CO2 semi-rich solvent 706c then continues to cascade through absorber 703. Advantageously, by cooling the solvent, the temperature of the solvent is reduced. A solvent with a reduced temperature will have an increased loading of CO2, which in turn reduces the heat of desorption energy required in the regenerator 710.

[0243] As the flue gas 701 a passes up through the absorber 703, it is depleted of CO2 and eventually forms CO2 lean flue gas 701 b. When the flue gas 701 a has passed through packing 703b, CO2 lean flue gas 701 b is formed. The CC>2 lean flue gas 701 b passes through a water wash section in packing 703c to recover any solvent and / or water that may be present in the CC>2 lean flue gas 701 b. The solvent is removed from the CO2 lean flue gas 701 b by reducing the temperature of the CO2 lean flue gas 701 b to a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C by contacting the CO2 lean flue gas 701 b with wash water 721 c. Once the wash water 721 c has cooled the CO2 lean flue gas 701 b, wash water 721 a is formed. Wash water 721 a passes through a water wash pump 719 to form wash water 721 b. The water wash pump 719 provides sufficient pressure to feed the wash water 721 b back into the absorber 703. Wash water 721 b passes through a water wash cooler 720, which cools the wash water 721 b and thereby forming wash water 721 c.

[0244] Once the CO2 lean flue gas 701 b has been washed in the water wash section, the CO2 lean flue gas 701 b continues to pass up through the absorber 703 to be released from the top of the absorber 703 as CO2 lean flue gas 701 b. The absorber 703 further includes a demister 703d, through which the CO2 lean flue gas 701 b passes through before leaving the absorber 703. The demister 703d is used to remove liquid droplets from the CO2 lean flue gas 701 b.

[0245] When the low-heat, CO2 semi-rich solvent 706c reaches the bottom of the absorber 703, the solvent is rich in CO2 and forms low-heat, CO2 rich solvent 709a. The low-heat, CO2 rich solvent 709a is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C. The low-heat, CO2 rich solvent 709a passes through a CO2 rich solvent pump 707 to form low- heat, CC>2 rich solvent 709b. The low-heat, CC>2 rich solvent 709b is typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 35 to 50°C, or, from 35 to 45°C, or, 40°C. The low-heat, CO2 rich solvent 709b is regenerated in regenerator 710, to reform low-heat, CO2 lean solvent 717h. The regenerator 710 contains packing to maximise the surface area to volume ratio. The packing is shown by references 710a, 710b and 710c in Figure 7. The packing 710a is present in the half of the regenerator 710 connected to a reboiler 715, this part is the bottom of the regenerator 710. The packing 710c is present in the part of the regenerator 710 connected to a condenser 711 , this part is the top of the regenerator 710. Packing 710b is present between packing 710a and 710c. Packings 710a and 710b are placed in specific locations in the regenerator 710 to maintain the required temperature profile in the regenerator 710. The regenerator 710 is operated at a pressure of from 0.8 to 3.0 bar(g), or at 2.0 bar(g). The regenerator 710 is operated at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C or, from 130 to 140°C, or, 136°C. Packing 710c is placed in the specified location to wash any vapours present in the top of the regenerator 710 and to recover the solvent and water vapours that have risen to the top of the regenerator 710.

[0246] The low-heat, CO2 rich solvent enters the regenerator 710 via a cross-over heat exchanger 708. The low-heat CO2 rich solvent 709b passes to the cross-over heat exchanger 708. In the cross-over heat exchanger 708, the low-heat, CO2 rich solvent 709b is heated by a high-heat, CC>2 lean solvent 717f to form high-heat, CO2 rich solvent 709c. The high-heat, CO2 rich solvent 709c is typically at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 113°C.

[0247] The high-heat, CC>2 rich solvent 709c enters the regenerator 710 above packing 710b and cascades down the regenerator 710 to below packing 710a. Inside the regenerator, the high-heat, CC>2 rich solvent 709c is heated further through contact with a high-heat vapour 717d. Typically, the high-heat vapour 717d flows upwards through the regenerator 710, counter-current to the high-heat, CO2 rich solvent 709c. Upon heating, the reaction between the active components of the high-heat, CO2 rich solvent 709c and CO2 reverses, releasing CC>2 gas and forming a high-heat, CO2 semi-lean solvent 717a. The high-heat, CO2 semi-lean solvent 717a is at a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 130 to 140°C, or, at 136°C.

[0248] The CC>2gas and any high-heat vapour 717d present at the top of the regenerator 710 form stream 712a. Stream 712a passes to a condenser 711. Typically, the condenser 711 is a stripper condenser. The condenser 711 forms a condensate 712b from the stream 712a, which passes to a reflux drum 713. The reflux drum 713 separates the condensate 712b into gaseous CC>2712c and a reflux condensate 712d. The reflux condensate 712d then passes to a reflux pump 714 to form reflux condensate 712e. The reflux pump 714 is used to move the reflux condensate 712e back into the regenerator 710. The reflux condensate 712e then passes back into the regenerator 710 above the packing710c. Having passed through the condenser 711 , the condensate 712b and the subsequently formed reflux condensate 712d and reflux condensate 712e are typically at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C, or, from 30 to 40°C, or 35°C. The gaseous CO2 712c is the CO2 product stream and can be used in downstream processes.

[0249] Reflux condensate 712e enters the regenerator 710 above packing 710c and is heated to form preheated reflux condensate 723a. Typically, the preheated reflux condensate 723a is at a temperature of from 90 to 120°C, or, from 100 to 110°C, or, 105°C. The preheated reflux condensate 723a is withdrawn from the regenerator 710 from between the packings 710b and 710c and passes through a preheated reflux condensate pump 722 to form preheated reflux condensate 723b.

[0250] Typically, the preheated reflux condensate 723b is at a temperature of from 90 to 120°C, or, from 100 to 1 10°C, or, 105°C.

[0251] The high-heat, CO2 semi-lean solvent 717a is fed into a reboiler 715. Typically, the reboiler 715 is operating at a temperature of 115°C or greater, or at 1 19°C. Typically, the reboiler 715 is operating at a pressure of from 0.2 to 1 bar(g), or at 0.7 bar(g). Within the reboiler 715, a first part of the high-heat, CO2 semi-lean solvent 717a is boiled resulting in the formation of a high-heat solvent vapour 717b. A second part of the high-heat, CO2 semi-lean solvent 717a leaves the reboiler 715 as a high-heat, CO2 lean solvent 717e. Typically, the high-heat, CC>2 lean solvent 717e is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 717b is at a temperature of from 90 to 160°C, or, from 100 to 120°C, or, 119°C. Typically, the high-heat solvent vapour 717b comprises CC>2 and water vapour.

[0252] The high-heat solvent vapour 717b passes to a compressor 716, where the high-heat solvent vapour 717b is compressed to form hot, compressed solvent vapour 717c. Typically, the hot, compressed solvent vapour 717c is at a temperature of from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C, or, 193°C and a pressure of from 1 .05 to 3.05 bar(g), or at 2.05 bar(g). The hot, compressed solvent vapour 717c is mixed with preheated reflux condensate 723b to form high-heat compressed solvent vapour 717d. The high-heat compressed solvent vapour 717d has a temperature of from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or, 141 °C.

[0253] The high-heat compressed solvent vapour 717d enters the regenerator 710 below packing 710a.

[0254] The high-heat, CC>2 lean solvent 717e passes to a CC>2 lean solvent pump 724 to form high-heat, CO2 lean solvent 717f. Typically, the temperature of the high-heat, CC>2 lean solvent 717f is from 90 to 160°C, or, from 100 to 120°C, or, 119°C. High-heat CO2 lean solvent 717f passes into the cross-over heat exchanger 708 and is cooled through contact with the low-heat, CC>2 rich solvent 709b to form low-heat, CO2 lean solvent 717g. Typically, the low-heat, CO2 lean solvent 717g is at a temperature of 20 to 60°C, or, from 30 to 55°C, or 45°C. The low-heat, CO2 lean solvent 717g then passes through a CO2 lean solvent cooler 718 to form low-heat, CO2 lean solvent 717h before entering the absorber column 703. The low-heat, CO2 lean solvent 717h is now ready to repeat the absorption process again. Whilst the absorber 703 and regenerator 710 are shown to be columns in Figure 7, in alternative embodiments the absorber 703 and / or regenerator 710 may be a Rotary Packed Bed (RPB).

[0255] Advantageously, by using heat from the high-heat compressed solvent vapour 717d in the regenerator 710, heat can be efficiently recovered from the high-heat solvent vapour 717c and therefore the amount of energy required by system 700 is reduced compared to conventional carbon capture systems. The full potential of the heat generated by the high-heat solvent vapour 717c can be used, which advantageously reduces the steam consumption. Thus, system 700 provides a more energy-efficient system for carbon capture compared to conventional carbon capture systems.

[0256] Further advantageously, a pressure difference between the reboiler 715 and regenerator 710 is used to ensure vaporisation of water in the reboiler 715, thereby increasing the amount of high-heat solvent vapour 717b being generated.

[0257] Further advantageously, a high pressure in the regenerator 710 is advantageous because this prevents any of the high-heat compressed solvent vapour 717d present at the top of the regenerator 710 from entering the condenser 711 , and instead ensures that the high-heat compressed solvent vapour 717d condenses. The heat generated by the condensation can then be used in the regenerator 710 to reverse the reaction between the active components of the high-heat, CO2 rich solvent 709c and CO2.

[0258] Further advantageously, a higher pressure in the regenerator 710 compared to the reboiler 715 is advantageous because this reduces the cooling duty of the condenser 711 , thereby providing additional energy savings.

[0259] Further advantageously, by mixing the hot, compressed solvent vapour 717c with the preheated reflux condensate 723b, the temperature of the hot, compressed solvent vapour entering the regenerator 710 is reduced, which in turn reduces the temperature of the regenerator 710. This advantageously reduces and / or prevents degradation of the solvent due to the very high temperatures prior to combination.

[0260] Further advantageously, by mixing the hot, compressed solvent vapour 717c with the preheated reflux condensate 723b, more of the reflux condensate 712e can be vapourised if the preheated reflux condensate 723a is preheated.

[0261] Example 8: Determination of the energy demand of systems 100-700

[0262] In one non-limiting example of the claimed invention, system 100 was compared with systems 200, 300, 400, 500, 600 and 700. In this non-limiting example, CDRMax® solvent (as sold by Carbon Clean Solution Ltd) was used in systems 100, 200, 300, 400, 500, 600 and 700. CDRMax® is an example of a solvent that can be used in systems 100, 200, 300, 400, 500, 600 and 700, other solvents can be used. In this nonlimiting example, Protreat® software by Optimized Gas Treating Inc. (OGT) was used, in which, the CDRMax® solvent had already been modelled and was used for the simulation of these systems to estimate the energy required for CO2 recovery from flue gas.

[0263] In this non-limiting example, a flue gas comprising 4 mol % CO2 was used in systems 100, 200, 300, 400, 500, 600 and 700 and the amount of energy required to remove from 53212-53480 kg / hourwas monitored. The removal of CO2 (approximately 90% of the CO2 in the flue gas) was estimated using the Protreat® simulation tool. The results are tabulated in Table 1 .

[0264] Table 1 : The energy required to remove 53212-53480 kg / hour from a flue gas comprising 4 mol % CO2

[0265] As can be seen from Table 1 , when a carbon capture solvent is regenerated by using heat sourced from the compressed vapour, the net energy required can be saved in the regeneration of a carbon capture solvent. As a result of the net energy required being saved in the regeneration of a carbon capture solvent, a more energy-efficient and cost-effective system(s) can be provided.

[0266] The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilized for realizing the invention in diverse forms thereof.

[0267] Although certain example aspects of the invention have been described, the scope of the appended claims is not intended to be limited solely to these examples. The claims are to be construed literally, purposively, and / or to encompass equivalents.

Claims

CLAIMS1 . A method for regenerating a solvent comprising carbon dioxide (CO2), the method comprising: providing a CO2 lean solvent; passing the CO2 lean solvent into a reboiler, wherein a first part of the CO2 lean solvent is heated to form a CO2 lean solvent vapour and wherein a second part of the CO2 lean solvent leaves the reboiler to further steps in regenerating the solvent comprising carbon dioxide (CO2); compressing the CO2 lean solvent vapour to form a compressed CO2 lean solvent vapour; passing the compressed CO2 lean solvent vapour through a regenerator; providing a CO2 rich solvent; passing the CO2 rich solvent through the regenerator, wherein heat from the compressed CO2 lean solvent vapour heats the CO2 rich solvent to form a CO2 lean solvent.

2. The method of claim 1 , wherein the method further comprises the step of: combining the compressed CO2 lean solvent vapour with a fluid to reduce the temperature of the compressed CO2 lean solvent vapour.

3. The method of claim 2, wherein the fluid is: a reflux condensate; or, a CO2 rich solvent; or, a preheated reflux condensate.

4. The method of claim 2 or claim 3, wherein the fluid is a reflux condensate and the method further comprises the step of: combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid in a reflux condensate heater; optionally, wherein the compressed CO2 lean solvent vapour is heat exchanged with the fluid in a reflux condensate heater.

5. The method of claim 2 or claim 3, wherein the fluid is a CO2 rich solvent and the method further comprises the step of: combined or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid in a CO2 rich solvent preheater; optionally, wherein the compressed CO2 lean solvent vapour is heat-exchanged with the fluid in a CO2 rich solvent preheater.

6. The method of claim 2 or claim 3, wherein the fluid is a preheated reflux condensate and the method further comprises the step of: combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid in a reflux condensate vaporiser;optionally, wherein the compressed CO2 lean solvent vapour is heat-exchanged with the fluid in a reflux condensate vaporiser.

7. The method of any one of claim 1 to 6, wherein the temperature of the compressed CO2 lean solvent vapour is at from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C.

8. The method of any one of claims 2 to 7, wherein upon combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

9. The method of any one of claims 2 to 8, wherein the fluid is a reflux condensate or a CO2 rich solvent, and the fluid is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C prior to combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid.

10. The method of any one of claims 2 to 9, wherein the fluid is a reflux condensate and upon combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.11 . The method of any one of claims 2 to 9, wherein the fluid is a CO2 rich solvent and upon combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or 137 °C.

12. The method of any one of claims 2 to 8, wherein the fluid is a preheated reflux condensate, and the fluid is at a temperature of from 90 to 120°C, or, from 100 to 110°C, or, at 105°C prior to combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid.

13. The method of any one of claims 2 to 8 or claim 12, wherein the fluid is a preheated reflux condensate and upon combining or mixing or heat-exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

14. The method of any one of claims 1 to 13, wherein the CO2 lean solvent has a carbon dioxide concentration of from 0.0 to 1.0 mol L-1.

15. The method of any one of claims 1 to 14, wherein the CO2 rich solvent has a carbon dioxide concentration of from greater than 2.0 to 4.0 mol L-1.

16. The method of any one of claims 1 to 15, wherein the CO2 semi-lean solvent has a carbon dioxide concentration of from greater than 1.0 to 1.5 mol L-1.

17. The method of any one of claims 1 to 16, wherein the CO2 semi-rich solvent has a carbon dioxide concentration of from greater than 1 .5 to 2.0 mol L-1.

18. The method of any one of claims 1 to 17, wherein the regenerator operates at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C, or, from 130 to 140°C, or, 136°C.

19. The method of any one of claims 1 to 18, wherein the regenerator operates at a pressure of from 0.8 to 3.0 bar(g), or, from 1 .5 to 2.5 bar(g), or, at 2.0 bar(g).

20. The method of any one of claims 1 to 19, wherein the step of providing a CO2 rich solvent further comprises: contacting a flue gas with a CO2 lean solvent within one, two, three, four, five, six, seven, eight, nine or ten, or more, absorber column(s), wherein the absorber column(s) is (are) in fluid communication with the regenerator.

21. The method of claim 20, wherein the absorber column(s) is (are) in fluid communication with the regenerator through at least one cross-over heat exchanger.

22. The method of any one of claims 1 to 21 , wherein the CO2 lean solvent and / or the CO2 rich solvent is / are an intensified solvent; optionally, an intensified solvent comprising a tertiary amine, or, a secondary amine, or, a primary amine; optionally, an intensified solvent further comprising a tertiary amine, a sterically hindered amine, a polyamine, a salt and water; optionally, wherein the solvent is CDRMax® or, MEA.

23. The method of any one of claims 20 to 22, wherein the flue gas is from a coal, gas and / or oil-fired boiler, combined cycle power plant, coal gasification plant, hydrogen plant, biogas plant, waste to energy plant, steel plants, refineries, cement kiln, blast furnace, or any other plant which produces a flue gas.

24. The method of any one of claims 20 to 23, wherein the flue gas has an initial carbon dioxide (CO2) concentration of from 2.2 volume % (dry) to 51 volume % (dry), or, from 3 volume % (dry) to 12 volume % (dry), or, from 15 volume % (dry) to 22 volume % (dry), or, from 30 volume % (dry) to 45 volume % (dry).

25. The method of any one of claims 1 to 24, wherein the regenerator comprises or consists of a packed column, a static column, or, a Rotary Packed Bed (RPB).

26. The method of claim 25, wherein the regenerator comprises a packed column and where the packed column comprises one, two, three, four, five, six, seven, eight, nine or ten, or more, packing sections.

27. The method of any one of claims 20 to 26, wherein the absorber column(s) comprises (comprise), or consists (consist), of a packed column, a static column, or, a Rotary Packed Bed (RPB).

28. The method of any one of claims 20 to 27, wherein the absorber column comprises a packed column and wherein the packed column comprises one, two, three, four, five, six, seven, eight, nine or ten, or more, packing sections.

29. A system for regenerating a solvent comprising carbon dioxide (CO2), the system comprising: a regenerator; a reboiler configured to heat a CO2 lean solvent to form a CO2 lean solvent vapour; a compressor configured to compress the CO2 lean solvent vapour to form a compressed CO2 lean solvent vapour; and wherein the regenerator is configured to exchange heat between the compressed CO2 lean solvent vapour and a CO2 rich solvent so as to remove CO2 from the CO2 rich solvent to form a CO2 lean solvent.

30. The system of claim 29, wherein the system is further configured to combine the compressed CO2 lean solvent vapour with a fluid.31 . The system of claim 30, wherein the system is further configured to combine the compressed CO2 lean solvent vapour with the fluid prior to exchanging heat between the compressed CO2 lean solvent vapour and the CO2 rich solvent.

32. The system of claim 30 or claim 31 , wherein the fluid is: a reflux condensate; or, a CO2 rich solvent; or, a preheated reflux condensate.

33. The system of any one of claims 30 to 32, wherein the fluid is a reflux condensate and the system is configured to combine or mix or heat exchange the compressed CO2 lean solvent vapour with the fluid in a reflux condensate heater; optionally, wherein the system is configured to heat exchange the compressed CO2 lean solvent vapour with the fluid in a reflux condensate heater.

34. The system of any one of claims 30 to 32, wherein the fluid is a CO2 rich solvent and the system is configured to combine or mix or heat exchange the compressed CO2 lean solvent vapour with the fluid in a CO2 rich solvent preheater optionally, wherein the system is configured to heat exchange the compressed CO2 lean solvent vapour with the fluid in a CC>2 rich solvent preheater.

35. The system of any one of claims 30 to 32, wherein the fluid is a preheated reflux condensate and the system is configured to combine or mix or heat exchange the compressed vapour with the fluid in a reflux condensate vaporiser; optionally, wherein the system is configured to heat exchange the CO2 lean solvent vapour with the fluid in a reflux condensate vaporiser.

36. The system of any one of claims 29 to 35, wherein the temperature of the compressed CO2 lean solvent vapour is at from greater than 160 to 220°C, or, from 180 to 220°C, or, from 185 to 205°C, or, from 190 to 200°C.

37. The system of any one of claims 30 to 36, wherein upon combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

38. The system of any one of claims 30 to 37, wherein the fluid is a reflux condensate or a CO2 rich solvent, and the fluid is at a temperature of from 20 to 60°C, or, from 30 to 55°C, or, from 30 to 45°C prior to combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid.

39. The system of any one of claims 30 to 38, wherein the fluid is a reflux condensate and upon combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

40. The system of any one of claims 30 to 38, wherein the fluid is a CO2 rich solvent and upon combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C, or 137 °C.41 . The system of any one of claims 30 to 37, wherein the fluid is a preheated reflux condensate, and the fluid is at a temperature of from 90 to 120°C, or, from 100 to 1 10°C, or, at 105°C prior to combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid.

42. The system of any one of claims 30 to 37 or claim 41 , wherein the fluid is a preheated reflux condensate and upon combining or mixing or heat exchanging the compressed CO2 lean solvent vapour with the fluid, the temperature of the compressed CO2 lean solvent vapour reduces to from 90 to 160°C, or, from 130 to 155°C, or, from 135 to 145°C.

43. The system of any one of claims 29 to 42, wherein the CO2 lean solvent has a carbon dioxide concentration of from 0.0 to 1.0 mol L-1.

44. The system of any one of claims 29 to 43, wherein the CO2 rich solvent has a carbon dioxide concentration of from greater than 2.0 to 4.0 mol L-1.

45. The system of any one of claims 29 to 44, wherein the CO2 semi-lean solvent has a carbon dioxide concentration of from greater than 1 .0 to 1 .5 mol L-1.

46. The system of any one of claims 29 to 45, wherein the CO2 semi-rich solvent has a carbon dioxide concentration of from greater than 1 .5 to 2.0 mol L-1.

47. The system of any one of claims 29 to 46, wherein the regenerator operates at a temperature in the range of equal to or greater than 120°C, or, from 120 to 160°C, or, from 120 to 150°C, or, from 130 to 140°C, or, 136°C.

48. The system of any one of claims 29 to 47, wherein the regenerator operates at a pressure of from 0.8 to 3.0 bar(g), or, from 1 .5 to 2.5 bar(g), or, at 2.0 bar(g).

49. The system of any one of claims 29 to 48, wherein the system is further configured to: contact a flue gas with a CO2 lean solvent within one, two, three, four, five, six, seven, eight, nine or ten, or more, absorber column(s), wherein the absorber column(s) is (are) in fluid communication with the regenerator.

50. The system of claim 49, wherein the absorber column(s) is (are) in fluid communication with the regenerator through at least one cross-over heat exchanger.51 . The system of any one of claims 29 to 51 , wherein the CO2 lean solvent and / or the CO2 rich solvent is / are an intensified solvent; optionally, an intensified solvent comprising a tertiary amine, or, a secondary amine, or, a primary amine; optionally, an intensified solvent further comprising a tertiary amine, a sterically hindered amine, a polyamine, a salt and water; optionally, wherein the solvent is CDRMax®, or, MEA.

52. The system of any one of claims 49 to 51 , wherein the flue gas is from a coal, gas and / or oil-fired boiler, combined cycle power plant, coal gasification plant, hydrogen plant, biogas plant, waste toenergy plant, steel plants, refineries, cement kiln, blast furnace, or any other plant which produces a flue gas.

53. The system of any one of claims 49 to 52, wherein the flue gas has an initial carbon dioxide (CO2) concentration of from 2.5 volume % (dry) to 51 volume % (dry), or, from 3 volume % (dry) to 12 volume % (dry), or, from 15 volume % (dry) to 22 volume % (dry), or, from 30 volume % (dry) to 45 volume % (dry).

54. The system of any one of claims 29 to 53, wherein the regenerator comprises or consists of a packed column, a static column or a Rotary Packed Bed (RPB).

55. The system of any one of claims 54, wherein the regenerator comprises a packed column and wherein the packed column comprises one, two, three, four, five, six, seven, eight, nine or ten, or more, packing sections.

56. The system of any one of claims 49 to 55, wherein the absorber column(s) comprises (comprise), or consists (consist), of a packed column, a static column, or, a Rotary Packed Bed (RPB).

57. The system of any one of claims 49 to 56, wherein the absorber column comprises a packed column and wherein the packed column comprises one, two, three, four, five, six, seven, eight, nine or ten, or more, packing sections.

Images