A thermal system and method for coupling flue gas compression energy storage and carbon dioxide capture

Abstract

The application discloses a kind of coupling flue gas compression energy storage and carbon dioxide capture thermodynamic system and method, it is related to flue gas processing and energy storage technical field, including the flue gas pretreatment unit, gas compression unit, carbon dioxide separation unit and post-processing unit connected in sequence;Gas compression unit includes at least two stages of flue gas compressor, and the middle cooler is provided after each stage of flue gas compressor;Carbon dioxide separation unit includes capture tower and desorption tower, and lean-liquid heat exchanger is provided between capture tower and desorption tower;Energy storage unit is connected with gas compression unit, carbon dioxide separation unit respectively.The application realizes that carbon dioxide is discharged in flue gas, and can play the effect of energy storage, realizes the purpose of efficient emission reduction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flue gas treatment and energy storage, and in particular to a thermal system and method coupling flue gas compression energy storage and carbon dioxide capture. BACKGROUND

[0002] The huge amount of carbon emissions since the industrial revolution has led to serious greenhouse effect. Compared with 1861-1900, the global land temperature rose by 1.6℃ in 2015-2019. The extreme climate brought by the rising sea level and temperature has begun to seriously threaten human survival. Therefore, reducing carbon dioxide emissions to slow down the greenhouse effect has become a global consensus. So far, fossil fuel power generation is still the main source of CO2 emissions, accounting for 40% of the total global carbon dioxide emissions. Carbon dioxide capture and storage technology is one of the most promising emission reduction methods.

[0003] In recent years, renewable energy such as wind power and solar power has developed rapidly. However, the stability of these energy outputs is insufficient, and energy storage technology is needed to store energy and release energy when needed. Energy storage technology not only improves the economic performance of the thermal system, but also balances the peak and valley of electricity. Flue gas compression energy storage technology is currently the most efficient and most industrialized energy storage technology. Flue gas compression energy storage technology stores energy by compressing air into high-pressure gas, and releases energy by passing compressed gas into a steam turbine when energy is needed.

[0004] Based on the characteristics of the differential pressure type carbon dioxide capture system, a large amount of high-pressure gas not absorbed by the capture liquid is not utilized. In order to utilize this part of high-pressure gas, a new type of thermal system needs to be designed and developed. SUMMARY

[0005] Therefore, the present application provides a thermal system and method coupling flue gas compression energy storage and carbon dioxide capture, which realizes flue gas carbon dioxide emission reduction and energy storage effect, and achieves the purpose of efficient emission reduction.

[0006] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0007] A thermal system coupling flue gas compression energy storage and carbon dioxide capture, comprising: a flue gas pretreatment unit, a gas compression unit, a carbon dioxide separation unit and a post-treatment unit connected in sequence;

[0008] The gas compression unit comprises at least two stages of flue gas compressors, and each stage of flue gas compressor is provided with a intercooler;

[0009] The carbon dioxide separation unit comprises a capture tower and a desorption tower, and a lean- rich liquid heat exchanger is arranged between the capture tower and the desorption tower;

[0010] The energy storage unit is connected with the gas compression unit and the carbon dioxide separation unit respectively.

[0011] Optionally, the flue gas pretreatment unit is a cyclone separator, and an outlet of the cyclone separator is connected with an inlet of the gas compression unit.

[0012] Optionally, the gas compression unit is a two-stage flue gas compressor, and the two-stage flue gas compressor corresponds to a first-stage flue gas compressor and a second-stage flue gas compressor, and the intercooler includes a first-stage intercooler and a second-stage intercooler.

[0013] An outlet of the first-stage flue gas compressor is connected with a first inlet of the first-stage intercooler, a first outlet of the first-stage intercooler is connected with an inlet of the second-stage flue gas compressor, an outlet of the second-stage flue gas compressor is connected with a first inlet of the second-stage intercooler, and a first outlet of the second-stage intercooler is connected with a first inlet of the capture tower.

[0014] Optionally, the carbon dioxide separation unit further includes a rich-liquid pump and a lean-liquid pump, a first outlet of the capture tower is connected with a first inlet of the rich-lean liquid heat exchanger through the rich-liquid pump, a second inlet of the capture tower is connected with a first outlet of the rich-lean liquid heat exchanger, a first outlet of the desorption tower is connected with a second inlet of the rich-lean liquid heat exchanger through the lean-liquid pump, and a first inlet of the desorption tower is connected with a second outlet of the rich-lean liquid heat exchanger.

[0015] Optionally, the carbon dioxide separation unit further includes a reboiler, a second outlet of the desorption tower is connected with an inlet of the reboiler, and an outlet of the reboiler is connected with a second inlet of the desorption tower.

[0016] Optionally, the energy storage unit includes a compressed gas storage tank, a first valve, a low-temperature energy storage device, a regenerator, a steam turbine, a heat storage bin, and a cold storage bin.

[0017] An outlet of the compressed gas storage tank is connected with a first inlet of the low-temperature energy storage device through the first valve, and an inlet of the compressed gas storage tank is connected with a second outlet of the capture tower.

[0018] A first outlet of the low-temperature energy storage device is connected with a first inlet of the regenerator, a first outlet of the regenerator is connected with an inlet of the steam turbine, and an outlet of the steam turbine is connected with a second inlet of the regenerator.

[0019] A second inlet of the low-temperature energy storage device is connected with an outlet of the heat storage bin, and an inlet of the heat storage bin is connected with a second outlet of the first-stage intercooler and a second outlet of the second-stage intercooler respectively.

[0020] An outlet of the cold storage bin is connected with a second inlet of the first-stage intercooler and a second inlet of the second-stage intercooler respectively, and an inlet of the cold storage bin is connected with a second outlet of the low-temperature energy storage device.

[0021] Optionally, the post-processing unit is connected with a third inlet of the desorption tower.

[0022] The application discloses a thermal method for coupling flue gas compression energy storage and carbon dioxide capture.

[0023] S1: flue gas is introduced into a cyclone separator to remove solid impurities, and then the flue gas is discharged from the top of the cyclone separator and transported to a first flue gas compressor for first-stage compression;

[0024] S2: the flue gas compressed in the first stage is introduced into a first-stage intercooler to exchange heat with a heat storage medium, so that the flue gas is cooled for the first time, the flue gas after the first-stage compression and the first-stage cooling is introduced into a second flue gas compressor for second-stage compression, and the flue gas after the second-stage compression and the first-stage cooling is obtained;

[0025] S3: the flue gas after the second-stage compression and the first-stage cooling is introduced into a second-stage intercooler to exchange heat with the heat storage medium, so that the flue gas is cooled for the second time, the flue gas after the second-stage compression and the second-stage cooling is obtained, and the flue gas is introduced into a capture tower to absorb carbon dioxide;

[0026] S4: the capture liquid is introduced into the capture tower from the top of the capture tower, mixed with the flue gas after the second-stage compression and the second-stage cooling, absorbs carbon dioxide in the flue gas after the second-stage compression and the second-stage cooling to form a rich liquid, and the rich liquid falls into the bottom of the capture tower and is discharged from a first outlet at the bottom of the capture tower;

[0027] S5: the rich liquid discharged from the first outlet of the capture tower is pressurized by a rich liquid pump and introduced into a rich-lean liquid heat exchanger for preheating, the preheated rich liquid is introduced into a desorption tower from a first inlet at the top of the desorption tower for pressure reduction and temperature increase desorption;

[0028] S6: waste heat steam of a boiler is heated by a reboiler to heat the desorption tower, so that the desorption of carbon dioxide is promoted, the desorbed carbon dioxide is discharged from a third outlet at the top of the desorption tower and then flows to a post-processing unit;

[0029] S7: the lean liquid after desorption flows out from a first outlet at the bottom of the desorption tower, is preheated by a lean liquid pump in the rich-lean liquid heat exchanger, and then flows into the capture tower from a second inlet of the capture tower, so that a capture cycle is completed;

[0030] S8: the gas not absorbed by the capture liquid flows out from a second outlet at the top of the capture tower to a compressed gas storage tank, when energy needs to be released, the compressed air is released from the compressed gas storage tank, flows to a low-temperature energy storage device through a first valve for first-stage preheating by the heat storage medium, and then flows into a regenerator for second-stage preheating by exhaust steam discharged from a steam turbine;

[0031] S9: the air preheated for two stages flows into the steam turbine to do work and output energy; the gas discharged from the steam turbine flows into the regenerator to preheat the compressed gas;

[0032] S10: The low-temperature heat storage medium is discharged from the cold storage bin and enters the first-stage intercooler and the second-stage intercooler in two paths to cool the compressed gas discharged by the first-stage flue gas compressor and the second-stage flue gas compressor, respectively; the heat-absorbed and warmed heat storage medium in the two paths is mixed in the heat storage bin and then stored in the heat storage bin and flows into the hot-side inlet of the low-temperature energy storage device to preheat the compressed gas, thereby completing the circulation of the heat storage medium.

[0033] Compared with the prior art, the technical scheme provides a thermal system and method for coupling flue gas compression energy storage and carbon dioxide capture, which is based on the characteristics of the physical absorption method carbon dioxide capture technology, uses the difference in solubility of carbon dioxide at different pressures to capture carbon dioxide in flue gas, uses the unabsorbed high-pressure nitrogen-oxygen mixed gas as an energy storage medium, realizes the combination of flue gas compression energy storage and carbon dioxide capture technology, can store energy and realize efficient carbon dioxide capture, uses heat storage medium to cool the compressed gas, reduces the energy consumption of the compression process, uses the heat for preheating the compressed gas, improves the temperature of the gas at the inlet of the steam turbine, and improves the efficiency of the steam turbine and the energy storage efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor on the basis of the provided drawings.

[0035] Figure 1 A structural block diagram of a thermal system for coupling flue gas compression energy storage and carbon dioxide capture is provided.

[0036] Figure 2 A flowchart of a thermal method for coupling flue gas compression energy storage and carbon dioxide capture is provided. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0038] In this application, the terms such as first and second are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between such entities or operations, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment. Without more limitation, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or equipment including the element.

[0039] Referring to Figure 1 The application discloses a thermal system coupling flue gas compression energy storage and carbon dioxide capture, comprising: a flue gas pretreatment unit, a gas compression unit, a carbon dioxide separation unit and a post-treatment unit connected in sequence.

[0040] The gas compression unit comprises at least two stages of flue gas compressors, and a intercooler is arranged after each stage of flue gas compressors.

[0041] The carbon dioxide separation unit comprises a capture tower 7 and a desorption tower 11, and a lean-liquid-rich-liquid heat exchanger 9 is arranged between the capture tower 7 and the desorption tower 11.

[0042] An energy storage unit is connected with the gas compression unit and the carbon dioxide separation unit respectively.

[0043] Further, the flue gas pretreatment unit is a cyclone separator 1, and the outlet of the cyclone separator is connected with the inlet of the gas compression unit.

[0044] Further, the gas compression unit is two stages of flue gas compressors, and the two stages of flue gas compressors correspond to a first stage of flue gas compressor 2 and a second stage of flue gas compressor 4, and the intercooler comprises a first stage of intercooler 3 and a second stage of intercooler 5.

[0045] The outlet of the first stage of flue gas compressor 2 is connected with the first inlet of the first stage of intercooler 3, the first outlet of the first stage of intercooler 3 is connected with the inlet of the second stage of flue gas compressor 4, the outlet of the second stage of flue gas compressor 4 is connected with the first inlet of the second stage of intercooler 5, and the first outlet of the second stage of intercooler 5 is connected with the first inlet of the capture tower 7.

[0046] Further, the carbon dioxide separation unit further comprises a rich-liquid pump 8 and a lean-liquid pump 10, the first outlet of the capture tower 7 is connected with the first inlet of the lean-liquid-rich-liquid heat exchanger 9 through the rich-liquid pump 8, the second inlet of the capture tower 7 is connected with the first outlet of the lean-liquid-rich-liquid heat exchanger 9, the first outlet of the desorption tower 11 is connected with the second inlet of the lean-liquid-rich-liquid heat exchanger 9 through the lean-liquid pump 10, and the first inlet of the desorption tower 11 is connected with the second outlet of the lean-liquid-rich-liquid heat exchanger 9.

[0047] Further, the carbon dioxide separation unit further comprises a reboiler 12, the second outlet of the desorption tower 11 is connected with the inlet of the reboiler 12, and the outlet of the reboiler 12 is connected with the second inlet of the desorption tower 11.

[0048] Further, the energy storage unit comprises: a compressed gas storage tank 6, a first valve 17, a low-temperature energy storage device 16, a regenerator 18, a steam turbine 19, a heat storage bin 14, and a cold storage bin 15.

[0049] The outlet of the compressed gas storage tank 6 is connected with the first inlet of the low-temperature energy storage device 16 through the first valve 17, and the inlet of the compressed gas storage tank 6 is connected with the second outlet of the capture tower 7.

[0050] The first outlet of the low-temperature energy storage device 16 is connected with the first inlet of the regenerator 18, the first outlet of the regenerator 18 is connected with the inlet of the steam turbine 19, and the outlet of the steam turbine 19 is connected with the second inlet of the regenerator 18.

[0051] The second inlet of the low-temperature energy storage device 16 is connected with the outlet of the heat storage bin 14, and the inlet of the heat storage bin 14 is respectively connected with the second outlet of the first-stage intercooler 3 and the second outlet of the second-stage intercooler 5.

[0052] The outlet of the cold storage bin 15 is respectively connected with the second inlet of the first-stage intercooler 3 and the second inlet of the second-stage intercooler 5, and the inlet of the cold storage bin 15 is connected with the second outlet of the low-temperature energy storage device 16.

[0053] Further, the post-processing unit 13 is connected with the third inlet of the desorption tower 11.

[0054] Specifically, a thermal system coupled with flue gas compression energy storage and carbon dioxide capture comprises, in sequence, a cyclone separator 1, a first-stage flue gas compressor 2, a first-stage intercooler 3, a second-stage flue gas compressor 4, a second-stage intercooler 5, a capture tower 7, a lean liquid pump 10, a rich liquid pump 8, a lean-rich liquid heat exchanger 9, a desorption tower 11, a reboiler 12, a post-processing unit 13, a compressed gas storage tank 6, a first valve 17, a low-temperature energy storage device 16, a regenerator 18, a steam turbine 19, a heat storage bin 14, and a cold storage bin 15.

[0055] The cyclone separator 1 is used to remove dust and solid impurities in the flue gas, and then the flue gas flows into the first-stage flue gas compressor 2 for first compression, the high-temperature and high-pressure flue gas discharged is cooled by the first-stage intercooler 3, and then flows into the second-stage flue gas compressor 4 for second compression, and the flue gas discharged flows into the second-stage intercooler 5 for second cooling. The flue gas after the two compressions flows into the capture tower 7 and is mixed with the capture liquid, and the capture tower absorbs CO2 to form rich liquid.

[0056] After the rich liquid flows out of the bottom of the capture tower 7, it is pressurized by the rich liquid pump 8 and enters the lean-rich liquid heat exchanger 9 for preheating. It then enters the desorption tower 11 for decompression and temperature increase for desorption. The heat for the desorption process comes from the boiler waste heat in the reboiler 12. The high-purity CO2 is discharged from the top of the desorption tower 11 to the post-processing unit 13 for post-processing and other operations. The lean liquid captured after CO2 desorption flows out of the bottom drain pipe of the desorption tower 11. The high-temperature lean liquid flows into the lean-rich liquid heat exchanger 9 via the lean liquid pump 10 to preheat the lean liquid to promote the desorption of the rich liquid. Finally, the lean liquid flows back to the capture tower 7, completing the capture cycle.

[0057] The high-pressure nitrogen and oxygen mixture not absorbed by the captured liquid is discharged from the top of the capture tower 7 as an energy storage medium and flows into the compressed gas storage tank 6. When the system needs to release energy, the compressed gas is released from the compressed gas storage tank 6 and enters the low-temperature energy storage tank 16 through the first valve 17 for the first preheating. The preheated high-pressure gas flows into the regenerator 18 for the second preheating by the exhaust steam. After the two preheatings, the high-temperature and high-pressure gas enters the steam turbine 19 to perform work. The high-temperature exhaust steam after the work enters the regenerator 18 to preheat the compressed gas.

[0058] The heat storage medium used to preheat the compressed gas in the low-temperature accumulator 16 then flows into the cold storage bin 15. After preheating the compressed gas, the low-temperature heat storage medium is split into two streams, which flow into the primary intercooler 3 and the secondary intercooler 5, respectively, to cool the compressed gas discharged from the compressor outlet. The two high-temperature heat storage mediums, after cooling the compressed gas, merge in the heat storage bin 14 and then flow into the low-temperature accumulator 16 for combined preheating, completing the cycle.

[0059] and Figure 1 Corresponding to the above system, the embodiment of the present invention also provides a thermal method for coupling flue gas compression energy storage and carbon dioxide capture, which is used to Figure 1 The specific implementation of the system is as follows: Figure 2 As shown, the following steps are included:

[0060] S1: Flue gas is passed into cyclone separator 1 to remove solid impurities, and then the flue gas is discharged from the top of cyclone separator 1 and transported to the first-stage flue gas compressor 2 for first-stage compression;

[0061] S2: The flue gas after the primary compression is passed into the primary intercooler 3 for heat exchange with the heat storage medium and subjected to the first cooling, thereby obtaining the flue gas that has undergone the primary compression and primary cooling, and then passed into the secondary flue gas compressor 4 for the second compression, thereby obtaining the flue gas that has undergone the secondary compression and primary cooling;

[0062] S3: The flue gas that has undergone secondary compression and primary cooling is passed into the secondary intercooler 5 for heat exchange with the heat storage medium and a second cooling is performed to obtain the flue gas that has undergone secondary compression and secondary cooling and is passed into the capture tower 7 to absorb carbon dioxide;

[0063] S4: The capture liquid enters the capture tower 7 from the top of the capture tower 7 and is mixed with the flue gas after secondary compression and secondary cooling to absorb the carbon dioxide in the flue gas after secondary compression and secondary cooling to form a rich liquid, and the rich liquid falls to the bottom of the capture tower 7 and is discharged through the first outlet at the bottom of the capture tower 7;

[0064] S5: The rich liquid discharged from the first outlet of the capture tower 7 is pressurized by the rich liquid pump 8 and then enters the rich-lean liquid heat exchanger 9 for preheating, and the preheated rich liquid enters the desorption tower 11 from the first inlet at the top of the desorption tower 11 for pressure reduction and temperature rise desorption;

[0065] S6: The waste heat steam of the boiler is heated by the reboiler 12 to heat the desorption tower 11 to promote the desorption of carbon dioxide, and the desorbed carbon dioxide is discharged from the third outlet at the top of the desorption tower 11 and then flows to the post-processing unit 13;

[0066] S7: The lean liquid after desorption flows out from the first outlet at the bottom of the desorption tower 11, flows to the rich-lean liquid heat exchanger 9 through the lean liquid pump 10 to preheat the lean liquid, and then flows into the capture tower 7 from the second inlet of the capture tower 7 to complete the capture cycle;

[0067] S8: The gas not absorbed by the capture liquid flows out from the second outlet at the top of the capture tower 7 to the compressed gas storage tank 6, and when energy needs to be released, the compressed air is released from the compressed gas storage tank 6, flows to the low-temperature energy storage device 16 through the first valve 17 for first preheating by the heat storage medium, and then flows into the regenerator 18 for second preheating by the exhaust steam discharged from the steam turbine 19;

[0068] S9: The air preheated twice flows into the steam turbine 19 to do work and output energy; the gas discharged from the steam turbine 19 flows into the regenerator 18 to preheat the compressed gas;

[0069] S10: The low-temperature heat storage medium is discharged from the cold storage bin 15 and enters the first-stage intercooler 3 and the second-stage intercooler 5 in two paths to cool the compressed gas discharged from the first-stage flue gas compressor 2 and the second-stage flue gas compressor 4, respectively; the two paths of heat-absorbed and temperature-increased heat storage medium are mixed in the heat storage bin 14 and then stored in the heat storage bin 14, and then flow into the low-temperature energy storage device 16 to preheat the compressed gas, completing the heat storage medium cycle.

[0070] Further, the gas not absorbed by the capture liquid in S8 includes high-pressure nitrogen, oxygen, etc.

[0071] The various embodiments described in this specification are described with reference to a particular sequence or order, but the order of the steps can be modified so that particular sequences or orders make no significant contribution to the progress of the art. Moreover, certain features and subcombinations are of utility and can be employed without reference to other features and subcombinations. For purposes of clarity, not every embodiment or feature in this specification is described or shown. Embodiments that provide real benefits can include any embodiment or combination of features described in this specification— even if the range of benefits realized is not the full range of benefits. Those of ordinary skill can understand that information and signals can be represented using any of a variety of technologies and techniques. For the purposes of this description, the terms "information" and "signals" can be regarded as synonymous. Those of ordinary skill can appreciate that the signals can be analog or digital, and the like.

[0072] The foregoing description of the disclosed embodiments enables one of ordinary skill in the art to make or utilize the application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without the use of the inventive faculty. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A thermodynamic system coupling flue gas compression energy storage and carbon dioxide capture, characterized in that, The system comprises a flue gas pretreatment unit, a gas compression unit, a carbon dioxide separation unit and a post-treatment unit connected in sequence. The gas compression unit comprises at least two stages of flue gas compressors, and a middle cooler is arranged after each stage of flue gas compressors. The carbon dioxide separation unit comprises a capture tower and a desorption tower, and a lean-rich liquid heat exchanger is arranged between the capture tower and the desorption tower. An energy storage unit is connected with the gas compression unit and the carbon dioxide separation unit respectively. The flue gas pretreatment unit is a cyclone separator, and the outlet of the cyclone separator is connected with the inlet of the gas compression unit. The gas compression unit is two-stage flue gas compressors, which are a first-stage flue gas compressor and a second-stage flue gas compressor, and the middle cooler comprises a first-stage middle cooler and a second-stage middle cooler. The outlet of the first-stage flue gas compressor is connected with the first inlet of the first-stage middle cooler, the first outlet of the first-stage middle cooler is connected with the inlet of the second-stage flue gas compressor, the outlet of the second-stage flue gas compressor is connected with the first inlet of the second-stage middle cooler, and the first outlet of the second-stage middle cooler is connected with the first inlet of the capture tower. The carbon dioxide separation unit further comprises a rich-liquid pump and a lean-liquid pump, the first outlet of the capture tower is connected with the first inlet of the lean-rich liquid heat exchanger through the rich-liquid pump, the second inlet of the capture tower is connected with the first outlet of the lean-rich liquid heat exchanger, the first outlet of the desorption tower is connected with the second inlet of the lean-rich liquid heat exchanger through the lean-liquid pump, and the first inlet of the desorption tower is connected with the second outlet of the lean-rich liquid heat exchanger. The carbon dioxide separation unit further comprises a reboiler, the second outlet of the desorption tower is connected with the inlet of the reboiler, and the outlet of the reboiler is connected with the second inlet of the desorption tower. The energy storage unit comprises a compressed gas storage tank, a first valve, a low-temperature energy storage device, a heat recovery device, a steam turbine, a heat storage bin and a cold storage bin. The outlet of the compressed gas storage tank is connected with the first inlet of the low-temperature energy storage device through the first valve, and the inlet of the compressed gas storage tank is connected with the second outlet of the capture tower. The first outlet of the low-temperature energy storage device is connected with the first inlet of the heat recovery device, the first outlet of the heat recovery device is connected with the inlet of the steam turbine, and the outlet of the steam turbine is connected with the second inlet of the heat recovery device. The second inlet of the low-temperature energy storage device is connected with the outlet of the heat storage bin, and the inlet of the heat storage bin is connected with the second outlet of the first-stage middle cooler and the second outlet of the second-stage middle cooler respectively. The outlet of the cold storage bin is connected with the second inlet of the first-stage middle cooler and the second inlet of the second-stage middle cooler respectively, and the inlet of the cold storage bin is connected with the second outlet of the low-temperature energy storage device. The post-treatment unit is connected with the third outlet of the desorption tower. The system is applied to the thermal system of claim 1, and comprises the following steps:

2. A thermodynamic process coupling flue gas compression energy storage and carbon dioxide capture, characterized in that, S1: flue gas is introduced into a cyclone separator to remove solid impurities, and then the flue gas is discharged from the top of the cyclone separator and transported to a first-stage flue gas compressor for first-stage compression; S2: the flue gas compressed in the first stage is introduced into a first-stage middle cooler to exchange heat with a heat storage medium, so as to be cooled for the first time, and then the flue gas is introduced into a second-stage flue gas compressor for second-stage compression, so as to be compressed for the second time and cooled for the first time; ​ S3: The flue gas after secondary compression and primary cooling is introduced into the second intercooler to exchange heat with the heat storage medium, to be secondarily cooled, to obtain flue gas after secondary compression and secondary cooling, and to be introduced into the capture tower to absorb carbon dioxide; S4: The capture liquid is introduced into the capture tower from the top of the capture tower to mix with the flue gas after secondary compression and secondary cooling to absorb carbon dioxide in the flue gas after secondary compression and secondary cooling to form a rich liquid, and the rich liquid falls into the bottom of the capture tower and is discharged from the first outlet at the bottom of the capture tower; S5: The rich liquid discharged from the first outlet of the capture tower is introduced into the lean-rich liquid heat exchanger after being pressurized by the rich liquid pump to be preheated, and the preheated rich liquid is introduced into the desorption tower from the first inlet at the top of the desorption tower to be depressurized and heated to be desorbed; S6: The waste heat steam of the boiler is heated by the reboiler to heat the desorption tower to promote the desorption of carbon dioxide, and the desorbed carbon dioxide is discharged from the third outlet at the top of the desorption tower and then flows to the post-processing unit; S7: The lean liquid after desorption flows out from the first outlet at the bottom of the desorption tower, flows to the lean-rich liquid heat exchanger through the lean liquid pump to preheat the lean liquid, and then flows into the capture tower from the second inlet of the capture tower to complete the capture cycle; S8: The gas not absorbed by the capture liquid flows out from the second outlet at the top of the capture tower to the compressed gas storage tank, and when energy needs to be released, the compressed air is released from the compressed gas storage tank, flows to the low-temperature energy storage device through the first valve to be first preheated by the heat storage medium, and then flows into the regenerator to be secondarily preheated by the exhaust steam of the steam turbine; S9: The air preheated twice flows into the steam turbine to do work and output energy; the gas discharged from the steam turbine flows into the regenerator to preheat the compressed gas; S10: The low-temperature heat storage medium is discharged from the cold storage bin and enters the first intercooler and the second intercooler in two ways to cool the compressed gas discharged from the first flue gas compressor and the second flue gas compressor, respectively; the heat storage medium after absorbing heat and being heated in two ways is mixed in the heat storage bin, and then stored in the heat storage bin and introduced into the low-temperature energy storage device to preheat the compressed gas, to complete the heat storage medium cycle.

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