Carbon dioxide trapping system capable of recycling waste heat and waste heat utilization module thereof

Abstract

The utility model provides a waste heat utilization module for a carbon dioxide capture system and the carbon dioxide capture system for waste heat recovery and utilization, wherein the carbon dioxide capture system comprises the waste heat utilization module. The waste heat utilization module utilizes a working medium steam compression device to compress and heat working medium steam carrying waste heat recovered from a carbon dioxide capture system into compressed working medium steam so as to improve the quality of the recovered waste heat, and then the compressed working medium steam is reused for medium barren liquor at the bottom of a desorption tower through a waste heat utilization device for carbon dioxide desorption. And the quality of the recycled waste heat is improved through compression, and efficient utilization of the waste heat is achieved. The carbon dioxide trapping system adopts the waste heat recovery heat exchanger to replace a traditional cooler, and realizes recovery, quality improvement and effective utilization of low-grade heat energy by utilizing a circulating working medium, so that sufficient recovery and utilization of internal energy of the carbon dioxide trapping system are realized; and the heat consumption and the operation cost of the carbon dioxide capture system are effectively reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of carbon dioxide capture, in particular to a waste heat utilization module for a carbon dioxide capture system and a carbon dioxide capture system comprising the waste heat utilization module and utilizing waste heat. Background Art

[0002] Carbon dioxide capture is an important technical choice for deep emission reduction in fossil energy industries such as thermal power, steel, cement, and chemical industry. Carbon dioxide capture technology based on chemical absorption is considered to be one of the most promising technical routes for large-scale carbon dioxide capture due to its mature process, high capture efficiency, and good flue gas adaptability. The process flow of traditional chemical absorption carbon dioxide capture is as follows: the carbon-containing flue gas emitted by thermal power plants, smelters, cement plants, chemical plants, etc. enters the bottom of the absorption tower after cooling, and contacts the absorbent sprayed from the top of the tower in reverse in the tower. During the gas-liquid contact process, the absorbent reacts chemically with the carbon dioxide in the flue gas to produce products such as carbamate, carbonate, and bicarbonate. The rich liquid after absorbing carbon dioxide is sent to the lean-rich liquid heat exchanger for heat exchange. The heated carbon dioxide rich liquid enters the desorption tower for carbon dioxide desorption and absorbent regeneration. At the bottom of the desorption tower, the carbon dioxide rich liquid exchanges heat with the steam in the reboiler. The absorbent is heated to a certain temperature for carbon dioxide desorption. The desorbed carbon dioxide is discharged from the top of the tower and compressed to a certain pressure after condensation and gas-liquid separation for subsequent transportation and storage. The lean liquid after desorption of carbon dioxide undergoes heat exchange in the lean-rich liquid heat exchanger, and then is cooled by the lean liquid cooler before entering the top of the absorption tower for the second cycle of carbon dioxide capture.

[0003] However, traditional chemical carbon dioxide capture has technical bottlenecks such as high energy consumption and high operating costs due to insufficient utilization of waste heat and poor synergy between cold and heat energy. In particular, the high energy consumption in the carbon dioxide desorption process (especially the steam consumption of the reboiler) and the cooling water consumption of the system have hindered the commercialization of this technology. Utility Model Content

[0004] In view of the above problems, the present invention proposes a waste heat utilization module for a carbon dioxide capture system and a carbon dioxide capture system comprising the waste heat recovery module, which overcomes the above problems or at least partially solves the above problems.

[0005] One object of the utility model is to provide a waste heat utilization module which can efficiently reuse the waste heat of a carbon dioxide capture system for carbon dioxide desorption.

[0006] Another object of the present invention is to provide a carbon dioxide capture system with waste heat recovery and utilization, so as to achieve coupled utilization of internal energy of the carbon dioxide capture system and effectively reduce the heat consumption and operating cost of the carbon dioxide capture system.

[0007] Another object of the present invention is to significantly reduce the cooling water consumption during the carbon dioxide capture process, thereby further reducing the carbon capture operating cost.

[0008] In particular, according to one aspect of the utility model, a waste heat utilization module for a carbon dioxide capture system is provided, wherein the carbon dioxide capture system has a waste heat recovery device for recovering waste heat of the carbon dioxide capture system by utilizing a process in which a liquid working medium evaporates into working medium steam, and the waste heat utilization module comprises:

[0009] A desorption tower, used for desorbing the carbon dioxide-rich liquid input therein;

[0010] a working fluid vapor compression device configured to compress and heat the working fluid vapor from the waste heat recovery device carrying waste heat recovered from the carbon dioxide capture system into compressed working fluid vapor; and

[0011] The waste heat utilization device is connected between the bottom of the desorption tower and the working fluid vapor compression device, and is configured to utilize the heat of the compressed working fluid vapor to heat the lean liquid at the bottom of the desorption tower through heat exchange to desorb carbon dioxide, so that the compressed working fluid vapor after the heat exchange at least partially undergoes a phase change and is converted into a liquid working fluid, and the working fluid after the heat exchange is output through an output port to allow the liquid working fluid to return to the waste heat recovery device.

[0012] Optionally, the waste heat utilization device includes a first reboiler respectively connected to the bottom of the desorption tower and the working fluid vapor compression device, which has a working fluid outlet as the output port, and is configured to allow the lean liquid drawn from the bottom of the desorption tower to exchange heat with the compressed working fluid vapor to desorb carbon dioxide, and then return to the bottom of the desorption tower, and allow the compressed working fluid vapor after heat exchange to at least partially undergo a phase change and be converted into a liquid working fluid, and output the working fluid after heat exchange through the working fluid outlet.

[0013] Optionally, the waste heat utilization device comprises:

[0014] a condensing heat exchanger connected to the working fluid vapor compression device, having a working fluid outlet as the output port, and configured to perform heat exchange between condensed water entering the condensing heat exchanger and compressed working fluid vapor from the working fluid vapor compression device to generate a high-temperature fluid containing water vapor, and to at least partially condense the compressed working fluid vapor after heat exchange into a liquid working fluid, and output the working fluid after heat exchange through the working fluid outlet; and

[0015] The second reboiler is connected to the bottom of the desorption tower and the condensing heat exchanger, respectively, and is configured to allow the lean liquid drawn from the bottom of the desorption tower to exchange heat with the water vapor generated based on the condensing heat exchanger to desorb carbon dioxide, and then return to the bottom of the desorption tower, and condense the water vapor into water and output it to the condensing heat exchanger.

[0016] Optionally, the waste heat utilization device further comprises:

[0017] A flash evaporator, connected between the condensing heat exchanger and the second reboiler, is configured to flash the high-temperature fluid from the condensing heat exchanger to generate water vapor and liquid water, and output the generated water vapor and liquid water to the second reboiler and the condensing heat exchanger respectively.

[0018] According to another aspect of the utility model, a waste heat recovery and utilization carbon dioxide capture system is provided, comprising an absorption tower, a lean-rich liquid heat exchanger and a regeneration gas compression device, wherein the carbon dioxide capture system also comprises a waste heat recovery device and the aforementioned waste heat utilization module, wherein

[0019] The cold rich liquid inlet, hot rich liquid outlet, hot lean liquid inlet and cold lean liquid outlet of the lean-rich liquid heat exchanger are respectively connected to the rich liquid outlet of the absorption tower, the first rich liquid feed inlet of the desorption tower, the hot lean liquid outlet of the desorption tower and the lean liquid feed inlet of the absorption tower through pipelines, and the regeneration gas outlet of the desorption tower is connected to the regeneration gas inlet of the regeneration gas compression device through pipelines;

[0020] The waste heat recovery device comprises at least one waste heat recovery heat exchanger, each of which has a working medium inlet and a working medium outlet, and is configured to respectively use the liquid working medium entering from the working medium inlet to perform heat exchange with one of the absorbent from the absorption tower, the lean liquid from the lean-rich liquid heat exchanger, the regeneration gas from the desorption tower, the compressed regeneration gas from the regeneration gas compression device, and the flue gas to be treated to enter the absorption tower, so that the liquid working medium after the heat exchange undergoes a phase change to generate working medium vapor which is output from the working medium outlet;

[0021] The steam inlet of the working fluid steam compression device is connected to the working fluid outlet of each waste heat recovery heat exchanger in the waste heat recovery device, and the output port of the waste heat utilization device is connected to the working fluid inlet of each waste heat recovery heat exchanger in the waste heat recovery device through a pipeline.

[0022] Optionally, the waste heat recovery device includes at least one of the following waste heat recovery heat exchangers:

[0023] A first waste heat recovery heat exchanger connected in a pipeline between the cold lean liquid outlet of the lean-rich liquid heat exchanger and the lean liquid feed inlet of the absorption tower, comprising a lean liquid inlet connected to the cold lean liquid outlet of the lean-rich liquid heat exchanger, a lean liquid outlet connected to the lean liquid feed inlet of the absorption tower, a first working fluid inlet and a first working fluid outlet, and configured to perform heat exchange between the liquid working fluid entering from the first working fluid inlet and the lean liquid entering from the lean liquid inlet, so that the liquid working fluid undergoes a phase change after the heat exchange to generate working fluid vapor which is output from the first working fluid outlet;

[0024] A second waste heat recovery heat exchanger connected in a pipeline between the regeneration gas outlet of the desorption tower and the regeneration gas inlet of the regeneration gas compression device, having a gas inlet connected to the regeneration gas outlet of the desorption tower, a gas outlet connected to the regeneration gas inlet of the regeneration gas compression device, a second working fluid inlet and a second working fluid outlet, and configured to perform heat exchange between the liquid working fluid entering from the second working fluid inlet and the regeneration gas entering from the gas inlet, so that the liquid working fluid undergoes a phase change after the heat exchange to generate working fluid vapor which is output from the second working fluid outlet;

[0025] A third waste heat recovery heat exchanger, which has a compressed gas inlet connected to the compressed gas outlet of the regeneration gas compression device, a third working medium inlet and a third working medium outlet, and is configured to perform heat exchange between the liquid working medium entering from the third working medium inlet and the compressed regeneration gas entering from the compressed gas inlet, so that the liquid working medium undergoes a phase change after the heat exchange to generate working medium vapor which is output from the third working medium outlet;

[0026] a fourth waste heat recovery heat exchanger, which has an absorbent inlet and an absorbent outlet, respectively connected to the absorbent outlet and the absorbent return port of the absorber tower, and a fourth working fluid inlet and a fourth working fluid outlet, and is configured to perform heat exchange between the liquid working fluid entering from the fourth working fluid inlet and the absorbent drawn from the absorber tower and entering from the absorbent inlet, so that the liquid working fluid undergoes a phase change after the heat exchange to generate working fluid vapor, which is output from the fourth working fluid outlet;

[0027] The fifth waste heat recovery heat exchanger has a flue gas inlet, a flue gas outlet connected to the flue gas inlet of the absorption tower, a fifth working fluid inlet and a fifth working fluid outlet, and is configured to allow the liquid working fluid entering from the fifth working fluid inlet to exchange heat with the flue gas to be treated entering from the flue gas inlet, so that the liquid working fluid after the heat exchange undergoes a phase change to generate working fluid vapor which is output from the fifth working fluid outlet.

[0028] Optionally, the carbon dioxide capture system further comprises:

[0029] The coupled heat exchanger is simultaneously connected to the pipeline between the rich liquid outlet of the absorption tower and the cold rich liquid inlet of the lean-rich liquid heat exchanger and the pipeline between the output port of the waste heat utilization device and the working fluid inlet of each waste heat recovery heat exchanger in the waste heat recovery device, and is configured to allow the working fluid output by the waste heat utilization device to exchange heat with the rich liquid output by the absorption tower therein.

[0030] Optionally, the carbon dioxide capture system further comprises:

[0031] The throttle valve is connected in the pipeline between the coupled heat exchanger and the working medium inlet of each of the waste heat recovery heat exchangers in the waste heat recovery device, and is configured to throttle and cool the working medium after heat exchange output by the coupled heat exchanger.

[0032] Optionally, the working fluid vapor compression device comprises a compressor; and

[0033] The carbon dioxide capture system further includes a converging mixer, which is respectively connected to the working medium outlet of each of the waste heat recovery heat exchangers in the waste heat recovery device and the steam inlet of the compressor, and is configured to collect and mix the working medium steam output by each of the waste heat recovery heat exchangers in the waste heat recovery device;

[0034] or,

[0035] The working fluid vapor compression device includes at least one compressor, the steam inlet of each compressor is connected to the working fluid outlet of one of the waste heat recovery heat exchangers in the waste heat recovery device, and each compressor is configured to compress the working fluid vapor output by the waste heat recovery heat exchanger connected thereto.

[0036] Optionally, the carbon dioxide capture system further comprises:

[0037] A splitter having an inlet connected to the rich liquid outlet of the absorption tower, a first outlet connected to the coupling heat exchanger and a second outlet connected to the second rich liquid feed port at the top of the desorption tower, and is configured to split the rich liquid output from the absorption tower into two paths and output them to the second rich liquid feed port of the desorption tower and the coupling heat exchanger respectively.

[0038] The waste heat utilization module for the carbon dioxide capture system provided by the utility model uses a working fluid vapor compression device to compress and heat the working fluid vapor carrying the waste heat recovered from the carbon dioxide capture system into compressed working fluid vapor to improve the quality of the recovered waste heat, and then the compressed working fluid vapor is reused by the waste heat utilization device for the lean liquid at the bottom of the desorption tower to desorb carbon dioxide. The quality of the recovered waste heat is improved by compression, thereby achieving efficient utilization of the waste heat.

[0039] Furthermore, in the waste heat utilization module for the carbon dioxide capture system provided by the utility model, the first reboiler is used as the waste heat utilization device, so that the lean liquid in the carbon dioxide drawn from the bottom of the desorption tower is used as the condensing medium to directly exchange heat with the high-temperature compressed working fluid steam. Thus, the reboiler and the working fluid condenser are combined into one, which simplifies the structure while efficiently utilizing the recovered waste heat, reduces the number of equipment, and reduces the system equipment cost.

[0040] Furthermore, in the waste heat utilization module for the carbon dioxide capture system provided by the utility model, the waste heat utilization device includes a second reboiler and a condensing heat exchanger, and water vapor is generated based on the condensing heat exchanger and supplied to the second reboiler, so that the water vapor is used in the second reboiler to heat the lean liquid in the carbon dioxide drawn from the bottom of the desorption tower 13 to achieve carbon dioxide desorption. This method can not only efficiently utilize the recovered waste heat, but also directly utilize the original reboiler of the desorption tower without modifying the reboiler (such as selecting materials suitable for the working fluid) or changing the operating conditions and processes of the reboiler, thereby reducing the modification cost of the system.

[0041] The waste heat recovery and utilization carbon dioxide capture system provided by the utility model adopts a waste heat recovery heat exchanger to replace the traditional cooler, and uses the circulating working fluid to realize the recovery and quality improvement of low-grade thermal energy such as absorption reaction heat, lean liquid sensible heat, desorption tower regeneration gas latent heat, carbon dioxide compression waste heat, and flue gas waste heat during the carbon dioxide capture process, and the quality-improved heat energy is reused for carbon dioxide desorption, thereby realizing the full recovery and utilization of the internal energy of the carbon dioxide capture system, and effectively reducing the heat consumption and operating cost of the carbon dioxide capture system. At the same time, these waste heat recovery heat exchangers also use working fluids to replace traditional cooling water to realize the cooling function of absorption liquid, lean liquid, regeneration gas, compressed carbon dioxide, flue gas, etc., thereby greatly reducing the consumption of cooling water in the carbon dioxide capture process, and further reducing the carbon capture operating cost.

[0042] Furthermore, the carbon dioxide capture system with waste heat recovery provided by the utility model, by setting a coupling heat exchanger, allows the cold rich liquid output by the absorption tower to first exchange heat with the working fluid output by the waste heat utilization device (i.e., the working fluid after waste heat recovery) in the coupling heat exchanger to preheat the cold rich liquid before entering the lean-rich liquid heat exchanger for heat exchange with the hot lean liquid, thereby achieving coupled utilization of the internal energy of the carbon dioxide capture system, further improving the waste heat utilization efficiency, and reducing the heat consumption and operating costs of the carbon dioxide capture system.

[0043] The above description is only an overview of the technical solution of the utility model. In order to more clearly understand the technical means of the utility model, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are listed below.

[0044] Based on the detailed description of the specific embodiments of the present invention in combination with the accompanying drawings below, those skilled in the art will become more aware of the above and other purposes, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the technical solution of the utility model, some embodiments of the utility model will be described below with reference to the accompanying drawings. Those skilled in the art should understand that the same figure number indicates the same or similar parts or components in different drawings; the drawings of the utility model are not necessarily drawn to scale. In the drawings:

[0046] Figure 1 is a schematic structural block diagram of a waste heat utilization module for a carbon dioxide capture system according to an embodiment of the utility model;

[0047] Figure 2 It is a structural schematic diagram of a carbon dioxide capture system for waste heat recovery and utilization according to an embodiment of the utility model;

[0048] Figure 3 It is a structural schematic diagram of a carbon dioxide capture system for waste heat recovery according to another embodiment of the utility model;

[0049] Figure 4 It is a structural schematic diagram of a carbon dioxide capture system for waste heat recovery according to another embodiment of the utility model;

[0050] Figure 5 It is a structural schematic diagram of a carbon dioxide capture system for waste heat recovery and utilization according to another embodiment of the utility model;

[0051] Figure 6 A schematic diagram of a fourth waste heat recovery heat exchanger using multi-stage parallel sub-heat exchangers according to an embodiment of the utility model;

[0052] Figure 7 It is a schematic diagram of a fourth waste heat recovery heat exchanger using a multi-stage series-connected sub-heat exchanger according to an embodiment of the utility model;

[0053] Figure 8 It is a schematic diagram of a regeneration gas compression device using multi-stage compression and a third waste heat recovery heat exchanger using multi-stage parallel inter-stage heat exchangers according to an embodiment of the utility model;

[0054] Fig. 9 It is a schematic diagram of a regeneration gas compression device using multi-stage compression and a third waste heat recovery heat exchanger using multi-stage series inter-stage heat exchangers according to an embodiment of the utility model. DETAILED DESCRIPTION

[0055] It should be understood by those skilled in the art that the embodiments described below are only a part of the embodiments of the present invention, rather than all the embodiments of the present invention, and the embodiments are intended to explain the technical principles of the present invention, rather than to limit the protection scope of the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should still fall within the protection scope of the present invention.

[0056] It should be noted that in the description of the present invention, the terms "center", "upper", "lower", "top", "bottom", "left", "right", "vertical", "horizontal", "inside", "outside" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings, which are only for the convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0057] Furthermore, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate component, or it can be a communication between the two elements. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0058] Traditional chemical carbon dioxide capture has technical bottlenecks such as high energy consumption, especially the high energy consumption in the carbon dioxide desorption process (for example, the steam consumption of the desorption tower) and the very high cooling water consumption of the system. Taking the capture system with a mass concentration of 30% monoethanolamine absorbent in commercial operation as an example, the energy consumption of solvent regeneration is 3.5-4.0GJ / t carbon dioxide, accounting for more than 60% of the total energy consumption of the system. However, thermodynamic analysis shows that the theoretical energy consumption required for the separation of carbon dioxide from flue gas in coal-fired power plants is only 0.16GJ / t carbon dioxide. Through research, the inventors of this application realized that the fundamental reason for the huge difference between the actual energy consumption and the theoretical energy consumption of the capture system is the irreversible energy loss inside the carbon capture system, especially the waste heat loss of flue gas cooling, the reaction heat loss of the carbon dioxide absorption unit, the sensible heat loss of the heat exchange unit, the latent heat loss of water evaporation in the desorption unit, and the waste heat loss of the compression unit. On this basis, traditional carbon dioxide capture systems require a large amount of cooling water for flue gas cooling, absorption tower cooling, warm lean liquid cooling, condenser cooling and compression unit cooling, etc. The consumption of cooling water further increases the operating cost of the carbon dioxide capture system.

[0059] Based on the above understanding, in order to solve or at least partially solve the aforementioned technical problems in the prior art, the utility model proposes a waste heat utilization module for a carbon dioxide capture system.

[0060] Figure 1 1 is a schematic structural block diagram of a waste heat utilization module 100 for a carbon dioxide capture system 10 according to an embodiment of the present invention. The carbon dioxide capture system 10 has a waste heat recovery device 150 for recovering waste heat in the capture process of the carbon dioxide capture system 10 by utilizing the process of evaporating liquid working medium into working medium steam. Figure 1 As shown, the waste heat utilization module 100 may generally include a desorption tower 130 , a working fluid vapor compression device 160 and a waste heat utilization device 170 .

[0061] The desorption tower 130 is used to desorb the carbon dioxide rich liquid input therein. The working fluid vapor compression device 160 is configured to compress and heat the working fluid vapor from the waste heat recovery device 150 carrying the waste heat recovered from the carbon dioxide capture system 10 into compressed working fluid vapor. The waste heat utilization device 170 is connected between the bottom of the desorption tower 130 and the working fluid vapor compression device 160, and is configured to utilize the heat of the compressed working fluid vapor to heat the lean liquid at the bottom of the desorption tower 130 through heat exchange to desorb carbon dioxide, so that at least part of the compressed working fluid vapor after heat exchange undergoes a phase change and is converted into a liquid working fluid, and the working fluid after heat exchange is output through the output port 1701 to allow the liquid working fluid to return to the waste heat recovery device 150.

[0062] The waste heat utilization module 100 for the carbon dioxide capture system provided in the embodiment of the utility model uses the working medium steam compression device 160 to compress and heat the working medium steam carrying the waste heat recovered from the carbon dioxide capture system into compressed working medium steam to improve the quality of the recovered waste heat, and then the compressed working medium steam is recycled to the middle lean liquid at the bottom of the desorption tower 130 for carbon dioxide desorption through the waste heat utilization device 170. The quality of the recovered waste heat is improved by compression, thereby achieving efficient utilization of the waste heat.

[0063] The utility model also proposes a waste heat recovery and utilization carbon dioxide capture system 10 , which includes a waste heat utilization module 100 .

[0064] Figure 2 Schematic diagram of the structure of a carbon dioxide capture system 10 for waste heat recovery according to an embodiment of the present invention.

[0065] Figure 3 FIG. 1 is a structural schematic diagram of a carbon dioxide capture system 10 for waste heat recovery according to another embodiment of the present invention.

[0066] Figure 4FIG. 1 is a structural schematic diagram of a carbon dioxide capture system 10 for waste heat recovery according to another embodiment of the present invention. Figure 5 This is a structural schematic diagram of a carbon dioxide capture system 10 for waste heat recovery according to another embodiment of the present invention. Figures 2 to 5 The waste heat utilization module 100 and the carbon dioxide capture system 10 of the present invention are introduced.

[0067] In some optional embodiments, such as Figure 4 or Figure 5 As shown, the waste heat utilization device 170 may include a first reboiler 171. The first reboiler 171 is connected to the bottom of the desorption tower 130 and the working medium vapor compression device 160, respectively, and has a working medium outlet 171d as an output port 1701. The first reboiler 171 is configured to heat-exchange the medium-lean liquid drawn from the bottom of the desorption tower 130 with the compressed working medium vapor to desorb carbon dioxide, and then return to the bottom of the desorption tower 130, and make the compressed working medium vapor after heat exchange at least partially undergo phase change (i.e., condensation) to be converted into liquid working medium, and output the working medium after heat exchange through the working medium outlet 171d, and the working medium after heat exchange contains at least part of the liquid working medium.

[0068] Specifically, the first reboiler 171 has a middle lean liquid inlet 171a, a middle lean liquid outlet 171b, a working medium inlet 171c and a working medium outlet 171d. A middle lean liquid outlet 134 and a middle lean liquid return port 135 are provided at the bottom of the desorption tower 130. The middle lean liquid inlet 171a and the middle lean liquid outlet 171b of the first reboiler 171 are respectively connected to the middle lean liquid outlet 134 and the middle lean liquid return port 135 at the bottom of the desorption tower 130, and the working medium inlet 171c is connected to the working medium vapor compression device 160.

[0069] In this embodiment, the first reboiler 171 can be regarded as a condenser, and the carbon dioxide lean liquid drawn from the bottom of the desorption tower 13 is used as a condensing medium to exchange heat with the high-temperature compressed working fluid steam. The lean liquid directly absorbs the heat released by the compressed working fluid steam to desorb carbon dioxide, and the compressed working fluid steam is cooled and condensed. In this way, the reboiler and the working fluid condenser are combined into one, which simplifies the structure while efficiently utilizing the recovered waste heat, reduces the number of equipment, and reduces the system equipment cost.

[0070] In some other optional embodiments, see Figure 2As shown, the waste heat utilization device 170 may include a second reboiler 172 and a condensing heat exchanger 174. The condensing heat exchanger 174 is connected to the working fluid vapor compression device 160 and has a working fluid outlet 174b as an output port 1701. The condensing heat exchanger 174 is configured to heat exchange the condensed water entering the condensing heat exchanger 174 with the compressed working fluid vapor from the working fluid vapor compression device 160 to produce a high-temperature fluid containing water vapor, and to condense the compressed working fluid vapor after heat exchange into a liquid working fluid at least partially, and output the working fluid after heat exchange through the working fluid outlet 174b. The second reboiler 172 is connected to the bottom of the desorption tower 130 and the condensing heat exchanger 174, respectively, and is configured to heat exchange the lean liquid drawn from the bottom of the desorption tower 130 with the water vapor generated based on the condensing heat exchanger 174 to desorb carbon dioxide, and then return to the bottom of the desorption tower 130, and condense the water vapor into water and output it to the condensing heat exchanger 174.

[0071] Optionally, a water vapor compression device (not shown) may be provided between the second reboiler 172 and the condensing heat exchanger 174 to compress and heat the generated water vapor. The compressed and heated water vapor then enters the second reboiler 172 .

[0072] In this embodiment, by setting up a condensing heat exchanger 174, water is used as a condensing medium to exchange heat with the high-temperature compressed working fluid steam to generate water vapor, and then the water vapor is used to enter the second reboiler 172 to heat the lean liquid in the carbon dioxide drawn from the bottom of the desorption tower 13 to achieve carbon dioxide desorption. This method can not only efficiently utilize the recovered waste heat, but also directly utilize the original reboiler of the desorption tower without modifying the reboiler (such as selecting a material suitable for the working fluid) or changing the operating conditions and process of the reboiler, thereby reducing the modification cost of the system.

[0073] In some further embodiments, see Figure 3 As shown, the waste heat utilization device 170 may also include a flash evaporator 173 connected between the second reboiler 172 and the condensing heat exchanger 174. The second reboiler 172 has a middle lean liquid inlet 172a, a middle lean liquid outlet 172b, a water vapor inlet 172c, and a condensed water outlet 172d. The flash evaporator 173 has a fluid inlet 173a, a liquid outlet 173b, and a water vapor outlet 173c. The condensing heat exchanger 174 has a working fluid inlet 174a, a working fluid outlet 174b, a condensed water inlet 174c, and a fluid outlet 174d.

[0074] The working medium inlet 174a of the condensing heat exchanger 174 is connected to the steam outlet 162 of the working medium vapor compression device 160, and the condensing heat exchanger 174 is configured to make the condensed water entering the condensing heat exchanger 174 and the compressed working medium vapor from the working medium vapor compression device 160 perform heat exchange to generate a high-temperature fluid (high-temperature water, water vapor, or a mixture of the two), and make the compressed working medium vapor after heat exchange at least partially condense into a liquid working medium, and output the working medium after heat exchange through the working medium outlet 174b. The fluid inlet 173a of the flash evaporator 173 is connected to the fluid outlet 174d of the condensing heat exchanger 174, and the liquid outlet 173b is connected to the condensed water inlet 174c of the condensing heat exchanger 174, and the flash evaporator 173 is configured to flash the high-temperature fluid from the condensing heat exchanger 174 to generate water vapor and liquid water. The liquid water generated in the flash evaporator 173 is output to the condensing heat exchanger 174 through the liquid outlet 173b and the condensed water inlet 174c, and the water vapor is output to the second reboiler 172 through the water vapor outlet 173c. The middle lean liquid inlet 172a, the middle lean liquid outlet 172b, the water vapor inlet 172c and the condensed water outlet 172d of the second reboiler 172 are respectively connected to the middle lean liquid outlet 134 and the middle lean liquid return port 135 at the bottom of the desorption tower 130, the water vapor outlet 173c of the flash evaporator 173 and the condensed water inlet 174c of the condensing heat exchanger 174, and the second reboiler 172 is configured to make the middle lean liquid drawn from the bottom of the desorption tower 130 exchange heat with the water vapor from the flash evaporator 173 to desorb carbon dioxide, and then return to the bottom of the desorption tower, while condensing the water vapor into condensed water and outputting it to the condensing heat exchanger 174.

[0075] Optionally, a water vapor compression device (not shown) may be provided between the second reboiler 172 and the flash evaporator 173 to compress and heat the generated water vapor. The compressed and heated water vapor then enters the second reboiler 172 .

[0076] In this embodiment, the flash evaporator 173 is used to flash evaporate the high-temperature fluid generated by the condensing heat exchanger 174, so as to further improve the quality of the generated water vapor, thereby further improving the utilization efficiency of the recovered waste heat.

[0077] See also Figure 2 As shown, the carbon dioxide capture system 10 may generally include an absorption tower 110, a lean-rich liquid heat exchanger 120, and a regeneration gas compression device 140. The carbon dioxide capture system 10 also includes a waste heat recovery device 150 and the aforementioned waste heat utilization module 100. The waste heat utilization module 100 specifically includes a desorption tower 130, a working fluid vapor compression device 160, and a waste heat utilization device 170.

[0078] The absorption tower 110 has a lean liquid feed inlet 112, a rich liquid outlet 111 at the bottom, and a flue gas inlet 115 at the bottom. The desorption tower 130 has a first rich liquid feed inlet 131, a hot lean liquid outlet 132 at the bottom, and a regeneration gas outlet 133 at the top. The first rich liquid feed inlet 131 is arranged on the tower body of the desorption tower 130, and can be located in the middle or upper middle part of the tower body, depending on the feed temperature of the rich liquid. The cold rich liquid inlet 121, the hot rich liquid outlet 122, the hot lean liquid inlet 123 and the cold lean liquid outlet 124 of the lean-rich liquid heat exchanger 120 are respectively connected to the rich liquid outlet 111 of the absorption tower 110, the first rich liquid feed inlet 131 of the desorption tower 130, the hot lean liquid outlet 132 of the desorption tower 130 and the lean liquid feed inlet 112 of the absorption tower 110 through pipelines. The regeneration gas outlet 133 of the desorption tower 130 is connected to the regeneration gas inlet 141 of the regeneration gas compression device 140 through a pipeline.

[0079] The waste heat recovery device 150 includes at least one waste heat recovery heat exchanger. Each waste heat recovery heat exchanger has a working medium inlet and a working medium outlet, and is configured to respectively use the liquid working medium entering from the working medium inlet to perform heat exchange with one of the absorbent from the absorption tower 110, the lean liquid from the lean-rich liquid heat exchanger 120, the regeneration gas from the desorption tower 130, the compressed regeneration gas from the regeneration gas compression device 140, and the flue gas to be treated to enter the absorption tower 110, so that the liquid working medium after the heat exchange undergoes a phase change to generate working medium vapor and output from the working medium outlet. The working medium can be selected from pure substances or mixtures such as ammonia, water, carbon dioxide, halogenated hydrocarbons (such as Freon), cyclic organic compounds, hydrocarbons, etc. The waste heat recovery device 150 utilizes low-temperature liquid working fluid to recover waste heat from at least one of the absorbent in the absorption tower 110, the lean liquid from the lean-rich liquid heat exchanger 120, the regenerated gas from the desorption tower 130, the compressed regenerated gas from the regenerated gas compression device 140, and the flue gas to be treated to enter the absorption tower 110 through heat exchange, while also providing them with cold capacity for cooling, thereby realizing the integration of cold and heat.

[0080] The working fluid steam compression device 160 has a steam inlet 161 and a steam outlet 162 , wherein the steam inlet 161 is connected to the working fluid outlet of each waste heat recovery heat exchanger in the waste heat recovery device 150 , and is used to compress the input working fluid steam into compressed working fluid steam and output it from the steam outlet 162 .

[0081] The waste heat utilization device 170 is connected between the bottom of the desorption tower 130 and the working fluid vapor compression device 140, and the output port 1701 of the waste heat utilization device 170 is connected to the working fluid inlet of each waste heat recovery heat exchanger in the waste heat recovery device 150 through a pipeline. The waste heat utilization device 170 is configured to use the heat of the compressed working fluid vapor to heat the lean liquid at the bottom of the desorption tower 130 through heat exchange to desorb carbon dioxide, so that at least part of the compressed working fluid vapor after heat exchange undergoes a phase change and is converted into a liquid working fluid, and outputs the working fluid after heat exchange containing at least part of the liquid working fluid. The working fluid is returned to each waste heat recovery heat exchanger in the waste heat recovery device 150 through a pipeline to complete the circulation of the working fluid.

[0082] The waste heat recovery and utilization carbon dioxide capture system 10 provided in the embodiment of the utility model adopts a waste heat recovery heat exchanger to replace the traditional cooler, and utilizes the circulating working fluid to realize the recovery and quality improvement of low-grade thermal energy such as absorption reaction heat, lean liquid sensible heat, desorption tower regeneration gas latent heat, carbon dioxide compression waste heat, and flue gas waste heat in the carbon dioxide capture process, and the quality-improved heat energy is reused for carbon dioxide desorption, thereby realizing the full recovery and utilization of the internal energy of the carbon dioxide capture system, and effectively reducing the heat consumption and operating cost of the carbon dioxide capture system. At the same time, these waste heat recovery heat exchangers also use working fluids to replace traditional cooling water to realize the cooling function of absorption liquid, lean liquid, regeneration gas, compressed carbon dioxide, flue gas, etc., thereby greatly reducing the consumption of cooling water in the carbon dioxide capture process, and further reducing the carbon capture operating cost.

[0083] In some optional embodiments, see Figures 3 to 5 As shown, the carbon dioxide capture system 10 may further include a coupling heat exchanger 180. The coupling heat exchanger 180 is simultaneously connected to the pipeline between the rich liquid outlet 111 of the absorption tower 110 and the cold rich liquid inlet 121 of the lean-rich liquid heat exchanger 120 and the pipeline between the output port 1701 of the waste heat utilization device 170 and the working medium inlet of each waste heat recovery heat exchanger in the waste heat recovery device 150, and is configured to allow the working medium (at least containing part of the liquid working medium) output by the waste heat utilization device 170 to perform heat exchange with the rich liquid output by the absorption tower.

[0084] The working medium is further condensed into liquid through heat exchange in the coupling heat exchanger 180, and then returned to each waste heat recovery heat exchanger in the waste heat recovery device 150 through the pipeline to complete the cycle of the working medium. The coupling heat exchanger 180 reuses the heat energy for the working medium after carbon dioxide desorption to further exchange heat with the cold rich liquid flowing out of the absorption tower to preheat the cold rich liquid, thereby realizing the coupling of the working medium cycle and the absorbent cycle in the carbon dioxide capture process.

[0085] The embodiment of the utility model provides a coupling heat exchanger 180 so that the cold rich liquid output from the absorption tower is first heat-exchanged with the working fluid output from the waste heat utilization device (i.e., the working fluid after waste heat recycling) in the coupling heat exchanger before entering the lean-rich liquid heat exchanger for heat exchange with the hot lean liquid to preheat the cold rich liquid, thereby achieving coupled utilization of the internal energy of the carbon dioxide capture system, further improving the waste heat utilization efficiency, and reducing the heat consumption and operating cost of the carbon dioxide capture system.

[0086] In some optional embodiments, the waste heat recovery device 150 may include at least one of a first waste heat recovery heat exchanger 151 , a second waste heat recovery heat exchanger 152 , a third waste heat recovery heat exchanger 153 , a fourth waste heat recovery heat exchanger 154 , and a fifth waste heat recovery heat exchanger 155 .

[0087] The first waste heat recovery heat exchanger 151 is connected in the pipeline between the cold lean liquid outlet 124 of the lean-rich liquid heat exchanger 120 and the lean liquid feed port 112 of the absorption tower 110, and has a lean liquid inlet 151a connected to the cold lean liquid outlet 124 of the lean-rich liquid heat exchanger 120, a lean liquid outlet 151b connected to the lean liquid feed port 112 of the absorption tower 110, a first working medium inlet 151c and a first working medium outlet 151d, and is configured to make the liquid working medium entering from the first working medium inlet 151c perform heat exchange with the lean liquid entering from the lean liquid inlet 151a, so that the liquid working medium after heat exchange undergoes phase change to generate working medium vapor and is output from the first working medium outlet 151d. The lean liquid after heat exchange is output from the lean liquid outlet 151b and then enters the absorption tower 110 through the lean liquid feed port 112 for carbon dioxide absorption.

[0088] The first waste heat recovery heat exchanger 151 can also be regarded as an evaporator, which deeply couples the working fluid evaporation process and the lean liquid cooling process in the carbon dioxide capture process, and uses the working fluid to replace the traditional cooling water to exchange heat with the lean liquid, thereby realizing both the working fluid endothermic evaporation function and the lean liquid cooling function.

[0089] The second waste heat recovery heat exchanger 152 is connected in the pipeline between the regeneration gas outlet 133 of the desorption tower 130 and the regeneration gas inlet 141 of the regeneration gas compression device 140, and has a gas inlet 152a connected to the regeneration gas outlet 133 of the desorption tower 130, a gas outlet 152b connected to the regeneration gas inlet 141 of the regeneration gas compression device 140, a second working medium inlet 152c and a second working medium outlet 152d, and is configured to make the liquid working medium entering from the second working medium inlet 152c and the regeneration gas entering from the gas inlet 152a perform heat exchange, so that the liquid working medium after heat exchange undergoes phase change to generate working medium vapor and is output from the second working medium outlet 152d. The regeneration gas after heat exchange flows out from 152b, is finally transported to the regeneration gas inlet 141 of the regeneration gas compression device 140 through the pipeline, and enters the regeneration gas compression device 140 from the regeneration gas inlet 141 to be compressed.

[0090] The second waste heat recovery heat exchanger 152 can also be regarded as an evaporator, which deeply couples the working fluid evaporation process and the desorption tower top gas (regeneration gas) cooling process in the carbon dioxide capture process, and uses the working fluid to replace the traditional cooling water to exchange heat with the desorption tower top outlet gas, thereby realizing both the working fluid endothermic evaporation function and the desorption tower top outlet gas cooling function.

[0091] The third waste heat recovery heat exchanger 153 has a compressed gas inlet 153a connected to the compressed gas outlet 142 of the regeneration gas compression device 140, a third working medium inlet 153c and a third working medium outlet 153d, and is configured to make the liquid working medium entering from the third working medium inlet 153c and the compressed regeneration gas entering from the compressed gas inlet 153a perform heat exchange, so that the liquid working medium after the heat exchange undergoes a phase change to generate working medium vapor and is output from the third working medium outlet 153d. The third waste heat recovery heat exchanger 153 also has a compressed gas outlet 153b, and the compressed regeneration gas after the heat exchange is output from the compressed gas outlet 153b for subsequent sealing and transportation.

[0092] The third waste heat recovery heat exchanger 1532 can also be regarded as an evaporator, which deeply couples the working fluid evaporation process and the carbon dioxide compressed gas cooling process in the carbon dioxide capture process, and uses the working fluid to replace the traditional cooling water to exchange heat with the carbon dioxide compressed gas, thereby realizing both the working fluid endothermic evaporation function and the carbon dioxide compressed gas cooling function.

[0093] The fourth waste heat recovery heat exchanger 154 has an absorbent inlet 154a and an absorbent outlet 154b connected to the absorbent outlet 113 and the absorbent return port 114 of the absorption tower 110, respectively (see Figure 4 and 5), the fourth working medium inlet 154c and the fourth working medium outlet 154d are configured to heat exchange the liquid working medium entering from the fourth working medium inlet 154c with the absorbent (or absorbent liquid) entering from the absorbent inlet 154a drawn from the absorption tower 110, so that the liquid working medium after the heat exchange undergoes a phase change (i.e., evaporates) to generate working medium vapor and output from the fourth working medium outlet 154d. The absorbent after the heat exchange is returned to the absorption tower 110 through the absorbent outlet 154b and the absorbent return port 114 to continue to absorb carbon dioxide. The absorbent can be selected from one or more types of absorbents such as inorganic ammonia, carbonates, alcohol amines, alkylamines, amino acids, etc., water system, less water system, anhydrous system, two-phase system mixture, etc.

[0094] The fourth waste heat recovery heat exchanger 154 can also be regarded as an evaporator, which deeply couples the working fluid evaporation process and the inter-stage cooling process of the carbon dioxide absorption tower, and uses the working fluid to replace the traditional cooling water to exchange heat with the carbon dioxide absorbent drawn from the absorption tower to absorb the reaction heat of the carbon dioxide absorption process, thereby realizing both the working fluid endothermic evaporation function and the inter-stage cooling function of the carbon dioxide absorption tower.

[0095] It should be noted that, in order to facilitate the purpose of the fourth waste heat recovery heat exchanger 154 to recover the absorption reaction heat in the absorption tower 110, Figures 1 to 5 The fourth waste heat recovery heat exchanger 154 is shown as being disposed in the absorption tower 110, but this does not mean that the fourth waste heat recovery heat exchanger 154 must be disposed in the absorption tower 110. Those skilled in the art can understand that the fourth waste heat recovery heat exchanger 154 can be disposed outside the absorption tower 110, and the absorbent in the absorption tower 110 is introduced into the fourth waste heat recovery heat exchanger 154 through the absorbent outlet 113 and the absorbent return port 114 of the absorption tower 110 for heat exchange and then the absorbent is returned to the absorption tower 110.

[0096] The fifth waste heat recovery heat exchanger 155 has a flue gas inlet 155a, a flue gas outlet 155b connected to the flue gas inlet 115 of the absorption tower 110, a fifth working medium inlet 155c and a fifth working medium outlet 155d, and is configured to make the liquid working medium entering from the fifth working medium inlet 155c and the flue gas to be treated entering from the flue gas inlet 155a perform heat exchange, so that the liquid working medium after heat exchange undergoes phase change (i.e., evaporates) to generate working medium vapor and outputs from the fifth working medium outlet 155d. The flue gas to be treated cooled by heat exchange enters the absorption tower 110 through the flue gas outlet 155b and the flue gas inlet 115 and contacts with the absorbent.

[0097] The fifth waste heat recovery heat exchanger 155 can also be regarded as an evaporator, which deeply couples the working fluid evaporation process and the flue gas cooling process in the carbon dioxide capture process, and uses the working fluid to replace the traditional cooling water to exchange heat with the flue gas, thereby realizing both the working fluid endothermic evaporation function and the flue gas cooling function.

[0098] In some optional embodiments, the fourth waste heat recovery heat exchanger 154 may include a plurality of sub-heat exchangers 154', and these sub-heat exchangers 154' may be connected in parallel or in series. Here, a plurality refers to 2 or more.

[0099] Figure 6 FIG. 1 is a schematic diagram of a fourth waste heat recovery heat exchanger using a multi-stage parallel sub-heat exchanger according to an embodiment of the present invention. Figure 6 As shown, when multiple sub-heat exchangers 154' are connected in parallel, the absorbent inlet 154a and the absorbent outlet 154b of each sub-heat exchanger 154' are respectively connected to the corresponding absorbent outlet 113 and the absorbent return port 114 on the absorption tower 110. The working medium inlet 154c of each sub-heat exchanger 154' can be connected to the waste heat utilization device 170 or the coupled heat exchanger 180 (when the coupled heat exchanger 180 is provided) through pipelines to receive the low-temperature liquid working medium output from the waste heat utilization device 170 or the coupled heat exchanger 180. The working fluid outlet 154d of each sub-heat exchanger 154' can be connected to the working fluid vapor compression device 160 respectively, or it can also be first connected to a confluence node (such as a confluence pipe, not shown in the figure), and the confluence node is further connected to the working fluid vapor compression device 160. The working fluid vapor output from the working fluid outlet 154d of all sub-heat exchangers 154' is collected through the confluence node and then transported to the working fluid vapor compression device 160.

[0100] Figure 7 FIG. 1 is a schematic diagram of a fourth waste heat recovery heat exchanger using a multi-stage series heat exchanger according to an embodiment of the present invention. Figure 7 As shown, in the case where a plurality of sub-heat exchangers 154' are connected in series, the absorbent inlet 154a and the absorbent outlet 154b of each sub-heat exchanger 154' are respectively connected to the corresponding absorbent outlet 113 and the absorbent return port 114 on the absorption tower 110. Along the direction of the working medium flow, the working medium inlet 154c of the first sub-heat exchanger 154' is connected to the waste heat utilization device 170 or the coupling heat exchanger 180 (in the case where the coupling heat exchanger 180 is provided) through a pipeline to receive the low-temperature liquid working medium output from the waste heat utilization device 170 or the coupling heat exchanger 180, the working medium outlet 154d of the last sub-heat exchanger 154' is connected to the working medium vapor compression device 160, and the working medium outlet 154d of each sub-heat exchanger 154' between the first and the last is connected to the working medium inlet 154c of the next adjacent sub-heat exchanger 154'.

[0101] In some optional embodiments, the regeneration gas compression device 140 may adopt multi-stage compression. Accordingly, the third waste heat recovery heat exchanger 153 may include multiple inter-stage heat exchangers 153'. These inter-stage heat exchangers 153' may be connected in parallel or in series to recover the waste heat of each stage of compressed gas.

[0102] Figure 8 Schematic diagram of a regeneration gas compression device using multi-stage compression and a third waste heat recovery heat exchanger using multi-stage parallel inter-stage heat exchangers according to an embodiment of the utility model. Figure 8 As shown, the regeneration gas compression device 140 includes a multi-stage sub-compressor 140', and the outlets of each stage of the sub-compressor 140' are sequentially connected in series to form a step-by-step compression structure. That is, the carbon dioxide regeneration gas adopts a multi-stage compression process.

[0103] In the case where multiple interstage heat exchangers 153' are connected in parallel, the multiple interstage heat exchangers 153' and the multi-stage sub-compressors 140' are arranged at intervals along the flow direction of the regenerated gas. Each interstage heat exchanger 153' except the last interstage heat exchanger 153' arranged along the flow direction of the compressed regenerated gas is arranged between the outlet of the previous sub-compressor 140' and the inlet of the next sub-compressor 140'. The compressed gas inlet 153a of the last interstage heat exchanger 153' is connected to the compressed gas outlet of the last sub-compressor 140', and the compressed gas outlet 153b can be connected to other subsequent carbon dioxide processing sections for subsequent storage and transportation. The working medium inlet 153c of each interstage heat exchanger 153' can be connected to the waste heat utilization device 170 or the coupled heat exchanger 180 (when the coupled heat exchanger 180 is provided) through a pipeline to receive the low-temperature liquid working medium output from the waste heat utilization device 170 or the coupled heat exchanger 180. The working fluid outlet 153d of each inter-stage heat exchanger 153' can be connected to the working fluid vapor compression device 160 respectively, or it can also be first connected to a confluence node (such as a confluence pipe, not shown in the figure), and the confluence node is further connected to the working fluid vapor compression device 160. The working fluid vapor output from the working fluid outlet 153d of all inter-stage heat exchangers 153' is collected through the confluence node and then transported to the working fluid vapor compression device 160.

[0104] Fig. 9 Schematic diagram of a regeneration gas compression device using multi-stage compression and a third waste heat recovery heat exchanger using multi-stage series inter-stage heat exchangers according to an embodiment of the utility model. Fig. 9 As shown, the regeneration gas compression device 140 includes a multi-stage sub-compressor 140', and the outlets of each stage of the sub-compressor 140' are sequentially connected in series to form a stage-by-stage compression structure.

[0105] In the case where multiple interstage heat exchangers 153' are connected in series, the multiple interstage heat exchangers 153' and the multi-stage sub-compressors 140' are arranged at intervals along the flow direction of the regenerated gas. Each interstage heat exchanger 153' except the last interstage heat exchanger 153' arranged along the flow direction of the compressed regenerated gas is arranged between the outlet of the previous sub-compressor 140' and the inlet of the next sub-compressor 140'. The compressed gas inlet 153a of the last interstage heat exchanger 153' is connected to the compressed gas outlet of the last sub-compressor 140', and the compressed gas outlet 153b can be connected to other subsequent carbon dioxide processing sections for subsequent storage and transportation. Along the direction of working medium flow, the working medium inlet 153c of the first interstage heat exchanger 153' is connected to the waste heat utilization device 170 or the coupling heat exchanger 180 (when the coupling heat exchanger 180 is provided) through a pipeline to receive the low-temperature liquid working medium output from the waste heat utilization device 170 or the coupling heat exchanger 180, and the working medium outlet 153d of the last interstage heat exchanger 153' is connected to the working medium vapor compression device 160, and the working medium outlet 153d of each interstage heat exchanger 153' between the first and the last is connected to the working medium inlet 153c of the next adjacent sub-heat exchanger interstage heat exchanger 153'.

[0106] In some optional embodiments, the power source of the regeneration gas compression device 140 is electrical energy, or high-temperature and high-pressure gas.

[0107] In some optional embodiments, the carbon dioxide capture system 10 may further include a throttle valve 191. The throttle valve 191 is connected to the pipeline between the waste heat utilization device 170 or the coupled heat exchanger 180 (when the coupled heat exchanger 180 is provided) and the working medium inlet of each waste heat recovery heat exchanger in the waste heat recovery device 150, and is configured to throttle and expand the working medium after heat exchange output by the waste heat utilization device 170 or the coupled heat exchanger 180, so as to further cool and condense the working medium.

[0108] In some optional embodiments, such as Figure 4 or Figure 5 As shown, the waste heat utilization device 170 may include a first reboiler 171. The first reboiler 171 is connected to the bottom of the desorption tower 130, the working fluid vapor compression device 160 and the coupling heat exchanger 180, respectively, and is configured to make the medium lean liquid drawn from the bottom of the desorption tower 130 exchange heat with the compressed working fluid vapor to desorb carbon dioxide, and then return to the bottom of the desorption tower 130, and make the compressed working fluid vapor after heat exchange at least partially change phase (i.e. condense) to convert into liquid working fluid, and output the working fluid after heat exchange, which contains at least part of liquid working fluid.

[0109] Specifically, the first reboiler 171 has a middle lean liquid inlet 171a, a middle lean liquid outlet 171b, a working fluid inlet 171c and a working fluid outlet 171d. A middle lean liquid outlet 134 and a middle lean liquid return port 135 are provided at the bottom of the desorption tower 130. The middle lean liquid inlet 171a and the middle lean liquid outlet 171b of the first reboiler 171 are respectively connected to the middle lean liquid outlet 134 and the middle lean liquid return port 135 at the bottom of the desorption tower 130, and the working fluid inlet 171c and the working fluid outlet 171d are respectively connected to the working fluid vapor compression device 160 and the coupling heat exchanger 180.

[0110] In some other optional embodiments, see Figure 3 As shown, the waste heat utilization device 170 may include a second reboiler 172 and a condensing heat exchanger 174. The condensing heat exchanger 174 is connected to the working fluid vapor compression device 160 and the coupling heat exchanger 180 respectively, and is configured to make the condensed water entering the condensing heat exchanger 174 heat exchange with the compressed working fluid vapor from the working fluid vapor compression device 160 to generate water vapor, and make the compressed working fluid vapor after heat exchange at least partially condense into liquid working fluid, and output the working fluid after heat exchange. The second reboiler 172 is connected to the bottom of the desorption tower 130 and the condensing heat exchanger 174 respectively, and is configured to make the lean liquid drawn from the bottom of the desorption tower 130 heat exchange with the water vapor from the condensing heat exchanger 174 to desorb carbon dioxide, and then return to the bottom of the desorption tower 130, and condense the water vapor into water and output it to the condensing heat exchanger 174.

[0111] Optionally, a water vapor compression device (not shown) may be provided between the second reboiler 172 and the condensing heat exchanger 174 to compress and heat the generated water vapor. The compressed and heated water vapor then enters the second reboiler 172 .

[0112] In some further embodiments, see Figure 3 As shown, the waste heat utilization device 170 may also include a flash evaporator 173 connected between the second reboiler 172 and the condensing heat exchanger 174. The second reboiler 172 has a middle lean liquid inlet 172a, a middle lean liquid outlet 172b, a water vapor inlet 172c, and a condensed water outlet 172d. The flash evaporator 173 has a fluid inlet 173a, a liquid outlet 173b, and a water vapor outlet 173c. The condensing heat exchanger 174 has a working fluid inlet 174a, a working fluid outlet 174b, a condensed water inlet 174c, and a fluid outlet 174d.

[0113] The working medium inlet 174a and the working medium outlet 174b of the condensing heat exchanger 174 are respectively connected to the steam outlet 162 of the working medium vapor compression device 160 and the coupling heat exchanger 180, and the condensing heat exchanger 174 is configured to make the condensed water entering the condensing heat exchanger 174 and the compressed working medium vapor from the working medium vapor compression device 160 to perform heat exchange to produce high-temperature fluid (high-temperature water, water vapor, or a mixture of the two), and make the compressed working medium vapor after heat exchange at least partially condense into liquid working medium, and output the working medium after heat exchange through the working medium outlet 174b. The fluid inlet 173a of the flash evaporator 173 is connected to the fluid outlet 174d of the condensing heat exchanger 174, and the liquid outlet 173b is connected to the condensed water inlet 174c of the condensing heat exchanger 174, and the flash evaporator 173 is configured to flash the high-temperature fluid from the condensing heat exchanger 174 to produce water vapor and liquid water. The liquid water produced in the flash evaporator 173 is output to the condensing heat exchanger 174 through the liquid outlet 173b and the condensed water inlet 174c. The middle lean liquid inlet 172a, the middle lean liquid outlet 172b, the water vapor inlet 172c and the condensed water outlet 172d of the second reboiler 172 are respectively connected to the middle lean liquid outlet 134 and the middle lean liquid return port 135 at the bottom of the desorption tower 130, the water vapor outlet 173c of the flash evaporator 173 and the condensed water inlet 174c of the condensing heat exchanger 174, and the second reboiler 172 is configured to make the middle lean liquid drawn from the bottom of the desorption tower 130 heat exchange with the water vapor from the flash evaporator 173 to desorb carbon dioxide, and then return to the bottom of the desorption tower, while condensing the water vapor into condensed water and outputting it to the condensing heat exchanger 174.

[0114] Optionally, a water vapor compression device (not shown) may be provided between the second reboiler 172 and the flash evaporator 173 to compress and heat the generated water vapor. The compressed and heated water vapor then enters the second reboiler 172 .

[0115] In some optional embodiments, the working fluid vapor compression device 160 may include a compressor. The carbon dioxide capture system 10 also includes a converging mixer 192 (shown only as a node in the figure), which is respectively connected to the working fluid outlet of each waste heat recovery heat exchanger in the waste heat recovery device 150 and the steam inlet of the compressor, and is configured to collect and mix the working fluid vapor output by each waste heat recovery heat exchanger in the waste heat recovery device 150. In other words, the working fluid vapor output by each waste heat recovery heat exchanger in the waste heat recovery device 150 is collected and mixed before entering the compressor for compression.

[0116] In some other optional embodiments, the working fluid vapor compression device 160 may include at least one compressor. The vapor inlet of each compressor is connected to the working fluid outlet of a waste heat recovery heat exchanger in the waste heat recovery device 150, and each compressor is configured to compress the working fluid vapor output by the waste heat recovery heat exchanger connected thereto. In other words, the working fluid vapor output by each waste heat recovery heat exchanger in the waste heat recovery device 150 is compressed by the compressors corresponding thereto.

[0117] In some optional embodiments, the power source of the working fluid vapor compression device 160 is electrical energy, or high-temperature and high-pressure gas.

[0118] In some embodiments, the carbon dioxide capture system 10 may further include a splitter 193. The splitter 193 has an inlet 193a connected to the rich liquid outlet 111 of the absorption tower 110, a first outlet 193b connected to the coupling heat exchanger 180, and a second outlet 193c connected to the second rich liquid feed port 136 at the top of the desorption tower 130, and is configured to split the rich liquid output from the absorption tower 110 into two paths and output them to the second rich liquid feed port 136 of the desorption tower 130 and the coupling heat exchanger 180 respectively.

[0119] In this embodiment, a diverter 193 is provided to divert a portion of the carbon dioxide rich liquid flowing out of the bottom of the absorption tower 110 directly into the desorption tower 130 to recover energy inside the desorption tower, thereby further improving energy recovery and utilization efficiency.

[0120] Of course, although not shown in the figure, those skilled in the art should understand that, without providing the coupling heat exchanger 180 , the first outlet 193 b of the splitter 193 can be directly connected to the cold rich liquid inlet 121 of the lean-rich liquid heat exchanger 120 .

[0121] Preferably, the mass of the split rich liquid directly entering the desorption tower 130 accounts for 5% to 40% of the total mass of the carbon dioxide rich liquid flowing out from the bottom of the absorption tower 110, so as to achieve an optimal balance between desorption and energy recovery.

[0122] In some optional embodiments, see Figure 3 The carbon dioxide capture system 10 may further include a working fluid storage tank 195 disposed between the coupled heat exchanger 180 and the throttle valve 191 , for caching the working fluid after heat exchange in the coupled heat exchanger 180 .

[0123] In some optional embodiments, the carbon dioxide capture system 10 may further include a gas-liquid separator 194 disposed between the regeneration gas outlet 133 of the desorption tower 130 and the regeneration gas compression device 140. In the case where the second waste heat recovery heat exchanger 152 is provided, the gas-liquid separator 194 is disposed between the second waste heat recovery heat exchanger 152 and the regeneration gas compression device 140.

[0124] Specifically, the gas outlet of the gas-liquid separator 194 is connected to the regeneration gas inlet 141 of the regeneration gas compression device 140, and the liquid outlet is connected to the liquid return port at the top of the desorption tower 130, so that the condensed and separated liquid returns to the desorption tower 130 from the liquid return port.

[0125] Various embodiments of the waste heat utilization module 100 and the carbon dioxide capture system 10 of the present invention are introduced above. The carbon dioxide capture system 10 of the present invention is described in detail below through specific examples.

[0126] Example 1

[0127] The structure of the waste heat recovery and utilization carbon dioxide capture system 10 of Example 1 is as follows: Figure 1 shown.

[0128] The carbon dioxide capture system 10 is provided with a first waste heat recovery heat exchanger 151, a second waste heat recovery heat exchanger 152, a third waste heat recovery heat exchanger 153, a fourth waste heat recovery heat exchanger 154 and a fifth waste heat recovery heat exchanger 155. The liquid working fluid exchanges heat in these waste heat recovery heat exchangers, takes away the absorption reaction heat, the sensible heat of the lean liquid, the latent heat of the desorption tower regeneration gas, the carbon dioxide compression waste heat and the flue gas waste heat in the carbon dioxide capture process, and at the same time, the working fluid undergoes a phase change to generate working fluid steam. The generated working fluid steam is collected and then compressed by the working fluid steam compression device 160 to generate high-temperature compressed working fluid steam. The compressed working fluid steam exchanges heat with the condensed water in the condensation heat exchanger 174 to turn it into a high-temperature fluid. The generated high-temperature fluid is flashed in the flash evaporator 173 to generate water vapor and enter the second reboiler 172 for carbon dioxide desorption. The liquid after flashing is mixed with the condensed water of the second reboiler 172 and enters the condensation heat exchanger 174.

[0129] Preferably, the temperature of the water vapor entering the second reboiler 172 is 5-10° C. higher than the temperature of the lean liquid at the bottom of the desorption tower 130 .

[0130] The high-temperature steam in the second reboiler 172 is converted into condensed water after heat exchange and directly enters the condensing heat exchanger 174 for recycling, thereby improving energy utilization efficiency.

[0131] A coupling heat exchanger 180 is also provided in the carbon dioxide capture system 10. The coupling heat exchanger 180 has a working medium inlet 180a, a working medium outlet 180b, a rich liquid inlet 180c and a rich liquid outlet 180d, which are respectively connected to the steam outlet 162 of the working medium vapor compression device 160, the throttle valve 191, the rich liquid outlet 111 of the absorption tower 110 and the cold rich liquid inlet 121 of the lean-rich liquid heat exchanger 120.

[0132] In order to further improve the utilization efficiency of heat energy, the high-temperature compressed working medium vapor in the condensing heat exchanger 174 is condensed and cooled after heat exchange, and the cooled working medium and the cold rich liquid of carbon dioxide flowing out from the bottom of the absorption tower 110 are heat exchanged in the coupling heat exchanger 180. After the heat exchange, the low-temperature working medium is further cooled by the throttle valve 191 and then enters the first waste heat recovery heat exchanger 151, the second waste heat recovery heat exchanger 152, the third waste heat recovery heat exchanger 153, the fourth waste heat recovery heat exchanger 154 and the fifth waste heat recovery heat exchanger 155 for waste heat recovery. The rich liquid of carbon dioxide enters the desorption tower 130 for carbon dioxide desorption after passing through the lean-rich liquid heat exchanger 120.

[0133] Example 2

[0134] The structure of the waste heat recovery and utilization carbon dioxide capture system 10 of Example 2 is as follows: Figure 2 shown.

[0135] The carbon dioxide capture system 10 is provided with a first waste heat recovery heat exchanger 151, a second waste heat recovery heat exchanger 152, a third waste heat recovery heat exchanger 153, a fourth waste heat recovery heat exchanger 154 and a fifth waste heat recovery heat exchanger 155. The liquid working fluid exchanges heat in these waste heat recovery heat exchangers, taking away the absorption reaction heat, the sensible heat of the lean liquid, the latent heat of the desorption tower regeneration gas, the carbon dioxide compression waste heat and the flue gas waste heat in the carbon dioxide capture process, and at the same time, the working fluid undergoes a phase change to generate working fluid steam. The generated working fluid steam is collected uniformly and then compressed centrally by the working fluid steam compression device 160 to generate high-temperature compressed working fluid steam. The high-temperature compressed working fluid steam directly exchanges heat with the lean liquid in the carbon dioxide flowing out of the bottom of the desorption tower 130 in the first reboiler 171 to achieve carbon dioxide desorption.

[0136] In order to further improve the utilization efficiency of thermal energy, the high-temperature compressed working medium steam in the first reboiler 171 is condensed and cooled after heat exchange, and the cooled working medium and the carbon dioxide cold rich liquid flowing out of the bottom of the absorption tower 110 are heat exchanged in the coupling heat exchanger 180. The low-temperature working medium after heat exchange is further cooled by the throttle valve 191 and then the waste heat of the next cycle is recovered. The carbon dioxide rich liquid enters the middle of the desorption tower 130 after passing through the lean-rich liquid heat exchanger 120 for carbon dioxide desorption.

[0137] Preferably, the temperature of the compressed working fluid vapor is at least 10° C. higher than the temperature of the lean liquid at the bottom of the desorption tower 130 .

[0138] The carbon dioxide cold rich liquid flowing out of the bottom of the absorption tower 110 is diverted by the diverter 193 to the top of the desorption tower 130 to recover energy inside the desorption tower. Preferably, the mass of the rich liquid diverted to the top of the desorption tower 130 accounts for 5%-40% of the total mass of the carbon dioxide rich liquid flowing out of the bottom of the absorption tower 110.

[0139] Example 3

[0140] The structure of the waste heat recovery and utilization carbon dioxide capture system 10 of Example 3 is as follows: Figure 3 shown.

[0141] The high-temperature carbon-containing flue gas directly enters the carbon dioxide absorption tower 110 without being cooled. The high-temperature flue gas exchanges heat with the absorption liquid at the bottom of the absorption tower 110 to achieve flue gas cooling. The heat released by the high-temperature flue gas in the absorption tower 110 is recycled through the fourth waste heat recovery heat exchanger 154. The absorption reaction heat, the sensible heat of the lean liquid, the latent heat of the desorption tower regeneration gas and the waste heat of carbon dioxide compression in the carbon dioxide capture process are absorbed by the first waste heat recovery heat exchanger 151, the second waste heat recovery heat exchanger 152, the third waste heat recovery heat exchanger 153 and the fourth waste heat recovery heat exchanger 154, and the working fluid undergoes a phase change to produce working fluid steam. The generated working fluid steam is collected uniformly and compressed centrally by the working fluid steam compression device 160 to generate high-temperature compressed working fluid steam. The high-temperature compressed working fluid steam directly exchanges heat with the lean liquid in the carbon dioxide flowing out of the bottom of the desorption tower 130 in the first reboiler 171 to achieve carbon dioxide desorption.

[0142] In order to further improve the utilization efficiency of thermal energy, the high-temperature compressed working medium steam in the first reboiler 171 is condensed and cooled after heat exchange, and the cooled working medium and the carbon dioxide cold rich liquid flowing out of the bottom of the absorption tower 110 are heat exchanged in the coupling heat exchanger 180. The low-temperature working medium after heat exchange is further cooled by the throttle valve 191 and then the waste heat of the next cycle is recovered. The carbon dioxide rich liquid enters the middle of the desorption tower 130 after passing through the lean-rich liquid heat exchanger 120 for carbon dioxide desorption.

[0143] Preferably, the temperature of the compressed working fluid vapor is at least 10° C. higher than the temperature of the lean liquid at the bottom of the desorption tower 130 .

[0144] The carbon dioxide cold rich liquid flowing out of the bottom of the absorption tower 110 is diverted by the diverter 193 to the top of the desorption tower 130 to recover energy inside the desorption tower. Preferably, the mass of the rich liquid diverted to the top of the desorption tower 130 accounts for 5%-40% of the total mass of the carbon dioxide rich liquid flowing out of the bottom of the absorption tower 110.

[0145] by Figure 3 The structure is based on the process flow simulation of the process flow with 30% diethanolamine as the carbon dioxide absorption medium using ASPEN PLUS simulation software. The simulation results are as follows: the flue gas cooling releases 0.56GJ / ton of CO2 heat, the carbon dioxide absorption process releases 1.93GJ / ton of CO2 heat, the lean liquid cooling process releases 1.90GJ / ton of CO2 heat, the regeneration gas cooling at the top of the desorption tower releases 0.67GJ / ton of CO2 heat, the carbon dioxide compression cooling process releases 0.49GJ / ton of CO2 heat, and the absorbent regeneration energy consumption is 3.25GJ / ton of CO2. The energy utilization efficiency of the waste heat recovery carbon dioxide capture system 10 of the utility model reaches 80%, and 4.29GJ / ton of CO2 heat can be recovered. The COP efficiency is 2.5, the input electric energy is 1.71GJ / ton of CO2, and 4.29GJ / ton of CO2 high-quality heat energy is generated, which is higher than the regeneration energy consumption of the desorption process, and a new type of carbon dioxide capture system driven by electricity can be realized.

[0146] According to any one of the above optional embodiments or a combination of multiple optional embodiments, the utility model can achieve the following beneficial effects:

[0147] (1) The quality of low-grade thermal energy such as flue gas waste heat, absorption reaction heat, lean liquid sensible heat, desorption tower latent heat, and carbon dioxide compression waste heat in the carbon dioxide capture process is improved through the integrated cold and hot process. The low-grade thermal energy in the carbon dioxide capture system is recycled and utilized, which greatly reduces the heat consumption and operating cost of the carbon dioxide desorption process.

[0148] (2) The integrated hot and cold process simultaneously provides the cooling capacity required in the carbon dioxide capture process, significantly reducing the cooling water consumption in the carbon dioxide capture process and further reducing the operating cost of carbon capture.

[0149] (3) The hot and cold integrated process can be driven by electricity. If the high-quality thermal energy generated by the hot and cold integrated process is greater than or equal to the heat required for the carbon dioxide desorption process, the new carbon dioxide capture system proposed in the utility model will not need to rely on external thermal energy, but can complete the cyclic capture of carbon dioxide only by relying on electricity, thereby realizing the electrification of chemical carbon dioxide capture technology and providing a feasible technical solution for carbon dioxide capture coupled with renewable electricity.

[0150] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0151] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived from the contents disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all such other variations or modifications.

Claims

1. A waste heat utilization module for a carbon dioxide capture system, characterized in that: The carbon dioxide capture system has a waste heat recovery device for recovering waste heat of the carbon dioxide capture system by utilizing the process of evaporation of liquid working medium into working medium steam. The waste heat utilization module comprises: A desorption tower, used for desorbing the carbon dioxide-rich liquid input therein; a working fluid vapor compression device configured to compress and heat the working fluid vapor from the waste heat recovery device carrying waste heat recovered from the carbon dioxide capture system into compressed working fluid vapor; and The waste heat utilization device is connected between the bottom of the desorption tower and the working fluid vapor compression device, and is configured to utilize the heat of the compressed working fluid vapor to heat the lean liquid at the bottom of the desorption tower through heat exchange to desorb carbon dioxide, so that the compressed working fluid vapor after the heat exchange at least partially undergoes a phase change and is converted into a liquid working fluid, and the working fluid after the heat exchange is output through an output port to allow the liquid working fluid to return to the waste heat recovery device.

2. The waste heat utilization module for a carbon dioxide capture system according to claim 1, characterized in that: The waste heat utilization device includes a first reboiler connected to the bottom of the desorption tower and the working fluid vapor compression device respectively, which has a working fluid outlet as the output port, and is configured to allow the lean liquid drawn from the bottom of the desorption tower to exchange heat with the compressed working fluid vapor to desorb carbon dioxide, and then return to the bottom of the desorption tower, and allow the compressed working fluid vapor after heat exchange to at least partially undergo a phase change and be converted into a liquid working fluid, and output the working fluid after heat exchange through the working fluid outlet.

3. The waste heat utilization module for a carbon dioxide capture system according to claim 1, characterized in that: The waste heat utilization device comprises: a condensing heat exchanger connected to the working fluid vapor compression device, having a working fluid outlet as the output port, and configured to perform heat exchange between condensed water entering the condensing heat exchanger and compressed working fluid vapor from the working fluid vapor compression device to generate a high-temperature fluid containing water vapor, and to at least partially condense the compressed working fluid vapor after heat exchange into a liquid working fluid, and output the working fluid after heat exchange through the working fluid outlet; and The second reboiler is connected to the bottom of the desorption tower and the condensing heat exchanger, respectively, and is configured to allow the lean liquid drawn from the bottom of the desorption tower to exchange heat with the water vapor generated based on the condensing heat exchanger to desorb carbon dioxide, and then return to the bottom of the desorption tower, and condense the water vapor into water and output it to the condensing heat exchanger.

4. The waste heat utilization module for a carbon dioxide capture system according to claim 3, characterized in that: The waste heat utilization device also includes: A flash evaporator, connected between the condensing heat exchanger and the second reboiler, is configured to flash the high-temperature fluid from the condensing heat exchanger to generate water vapor and liquid water, and output the generated water vapor and liquid water to the second reboiler and the condensing heat exchanger respectively.

5. A carbon dioxide capture system for waste heat recovery, comprising an absorption tower, a lean-rich liquid heat exchanger and a regeneration gas compression device, characterized in that: The carbon dioxide capture system further comprises a waste heat recovery device and a waste heat utilization module according to any one of claims 1 to 4, wherein The cold rich liquid inlet, hot rich liquid outlet, hot lean liquid inlet and cold lean liquid outlet of the lean-rich liquid heat exchanger are respectively connected to the rich liquid outlet of the absorption tower, the first rich liquid feed inlet of the desorption tower, the hot lean liquid outlet of the desorption tower and the lean liquid feed inlet of the absorption tower through pipelines, and the regeneration gas outlet of the desorption tower is connected to the regeneration gas inlet of the regeneration gas compression device through pipelines; The waste heat recovery device comprises at least one waste heat recovery heat exchanger, each of which has a working medium inlet and a working medium outlet, and is configured to respectively use the liquid working medium entering from the working medium inlet to perform heat exchange with one of the absorbent from the absorption tower, the lean liquid from the lean-rich liquid heat exchanger, the regeneration gas from the desorption tower, the compressed regeneration gas from the regeneration gas compression device, and the flue gas to be treated to enter the absorption tower, so that the liquid working medium after the heat exchange undergoes a phase change to generate working medium vapor which is output from the working medium outlet; The steam inlet of the working fluid steam compression device is connected to the working fluid outlet of each waste heat recovery heat exchanger in the waste heat recovery device, and the output port of the waste heat utilization device is connected to the working fluid inlet of each waste heat recovery heat exchanger in the waste heat recovery device through a pipeline.

6. The waste heat recovery and carbon dioxide capture system according to claim 5 is characterized in that: The waste heat recovery device includes at least one of the following waste heat recovery heat exchangers: A first waste heat recovery heat exchanger connected in a pipeline between the cold lean liquid outlet of the lean-rich liquid heat exchanger and the lean liquid feed inlet of the absorption tower, comprising a lean liquid inlet connected to the cold lean liquid outlet of the lean-rich liquid heat exchanger, a lean liquid outlet connected to the lean liquid feed inlet of the absorption tower, a first working fluid inlet and a first working fluid outlet, and configured to perform heat exchange between the liquid working fluid entering from the first working fluid inlet and the lean liquid entering from the lean liquid inlet, so that the liquid working fluid undergoes a phase change after the heat exchange to generate working fluid vapor which is output from the first working fluid outlet; A second waste heat recovery heat exchanger connected in a pipeline between the regeneration gas outlet of the desorption tower and the regeneration gas inlet of the regeneration gas compression device, having a gas inlet connected to the regeneration gas outlet of the desorption tower, a gas outlet connected to the regeneration gas inlet of the regeneration gas compression device, a second working fluid inlet and a second working fluid outlet, and configured to perform heat exchange between the liquid working fluid entering from the second working fluid inlet and the regeneration gas entering from the gas inlet, so that the liquid working fluid undergoes a phase change after the heat exchange to generate working fluid vapor which is output from the second working fluid outlet; A third waste heat recovery heat exchanger, which has a compressed gas inlet connected to the compressed gas outlet of the regeneration gas compression device, a third working medium inlet and a third working medium outlet, and is configured to perform heat exchange between the liquid working medium entering from the third working medium inlet and the compressed regeneration gas entering from the compressed gas inlet, so that the liquid working medium undergoes a phase change after the heat exchange to generate working medium vapor which is output from the third working medium outlet; a fourth waste heat recovery heat exchanger, which has an absorbent inlet and an absorbent outlet, respectively connected to the absorbent outlet and the absorbent return port of the absorber tower, and a fourth working fluid inlet and a fourth working fluid outlet, and is configured to perform heat exchange between the liquid working fluid entering from the fourth working fluid inlet and the absorbent drawn from the absorber tower and entering from the absorbent inlet, so that the liquid working fluid undergoes a phase change after the heat exchange to generate working fluid vapor, which is output from the fourth working fluid outlet; The fifth waste heat recovery heat exchanger has a flue gas inlet, a flue gas outlet connected to the flue gas inlet of the absorption tower, a fifth working fluid inlet and a fifth working fluid outlet, and is configured to allow the liquid working fluid entering from the fifth working fluid inlet to exchange heat with the flue gas to be treated entering from the flue gas inlet, so that the liquid working fluid after the heat exchange undergoes a phase change to generate working fluid vapor which is output from the fifth working fluid outlet.

7. The waste heat recovery and carbon dioxide capture system according to claim 5 is characterized in that: Also includes: The coupled heat exchanger is simultaneously connected to the pipeline between the rich liquid outlet of the absorption tower and the cold rich liquid inlet of the lean-rich liquid heat exchanger and the pipeline between the output port of the waste heat utilization device and the working fluid inlet of each waste heat recovery heat exchanger in the waste heat recovery device, and is configured to allow the working fluid output by the waste heat utilization device to exchange heat with the rich liquid output by the absorption tower therein.

8. The waste heat recovery and carbon dioxide capture system according to claim 7, characterized in that: Also includes: The throttle valve is connected in the pipeline between the coupled heat exchanger and the working medium inlet of each of the waste heat recovery heat exchangers in the waste heat recovery device, and is configured to throttle and cool the working medium after heat exchange output by the coupled heat exchanger.

9. The waste heat recovery and carbon dioxide capture system according to claim 5, characterized in that: The working fluid vapor compression device includes a compressor; and The carbon dioxide capture system further includes a converging mixer, which is respectively connected to the working medium outlet of each of the waste heat recovery heat exchangers in the waste heat recovery device and the steam inlet of the compressor, and is configured to collect and mix the working medium steam output by each of the waste heat recovery heat exchangers in the waste heat recovery device; or, The working fluid vapor compression device includes at least one compressor, the steam inlet of each compressor is connected to the working fluid outlet of one of the waste heat recovery heat exchangers in the waste heat recovery device, and each compressor is configured to compress the working fluid vapor output by the waste heat recovery heat exchanger connected thereto.

10. The waste heat recovery and carbon dioxide capture system according to claim 7, characterized in that: Also includes: A splitter having an inlet connected to the rich liquid outlet of the absorption tower, a first outlet connected to the coupling heat exchanger and a second outlet connected to the second rich liquid feed port at the top of the desorption tower, and is configured to split the rich liquid output from the absorption tower into two paths and output them to the second rich liquid feed port of the desorption tower and the coupling heat exchanger respectively.

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