Carbon dioxide capture system using heat pumps for waste heat recovery and utilization

Abstract

Provided is a carbon dioxide capture system using heat pumps for waste heat recovery and utilization. In the system, waste heat recovery and upgrading are performed, by means of a first waste heat recovery heat pump, on a lean solution in a medium-temperature section that has been cooled by means of a lean-rich solution heat exchanger, and / or waste heat recovery and upgrading are performed, by means of a third waste heat recovery heat pump, on reaction waste heat of an absorption solution; and recovered waste heat is used for heating a medium-lean solution at the bottom of a desorption tower to perform carbon dioxide desorption, thereby realizing the recovery and full upgrading of low-grade waste heat, and thus achieving the aim of full utilization of low-grade waste heat. By means of a first coupled heat exchanger and / or a second coupled heat exchanger, the system further makes the working medium, which is obtained after recovered heat energy is reused for carbon dioxide desorption, further exchange heat with a split cold rich solution to preheat the cold rich solution, thereby realizing coupled utilization of energy inside the carbon dioxide capture system, and thus effectively reducing the heat consumption and operating costs of the carbon dioxide capture system.

Description

A carbon dioxide capture system for recovering waste heat using a heat pump Technical Field

[0001] This invention relates to the field of carbon dioxide capture technology, and in particular to a carbon dioxide capture system that uses a heat pump to recover and utilize waste heat. Background Technology

[0002] Carbon dioxide capture (CO2) is a crucial technology for deep emission reduction in fossil fuel industries such as thermal power, steel, cement, and chemicals. Chemical absorption-based CO2 capture technology is considered one of the most promising approaches for large-scale CO2 capture due to its mature process, high capture efficiency, and good flue gas adaptability. The traditional chemical absorption CO2 capture process is as follows: Carbon-containing flue gas emitted from thermal power plants, smelters, cement plants, and chemical plants is cooled and then enters the bottom of an absorption tower. Inside the tower, it comes into counter-current contact with absorbent injected from the top. During this gas-liquid contact, the absorbent reacts chemically with the CO2 in the flue gas to produce products such as carbamates, carbonates, and bicarbonates. The enriched solution after CO2 absorption is sent to a lean-rich solution heat exchanger for heat exchange. The heated CO2-rich solution then enters a desorption tower for CO2 desorption and absorbent regeneration. At the bottom of the desorption tower, the CO2-rich solution exchanges heat with steam in a reboiler. The absorbent is heated to a certain temperature for CO2 desorption. The desorbed CO2 is discharged from the top of the tower, condensed, separated from the gas, and compressed to a certain pressure for subsequent transportation and storage. After desorbing carbon dioxide, the lean liquor exchanges heat in a lean-rich liquor heat exchanger, and then is cooled by a lean liquor cooler before entering the top of the absorption tower for a second cycle of carbon dioxide collection.

[0003] However, traditional chemical carbon dioxide capture suffers from technical bottlenecks such as high energy consumption and high operating costs due to insufficient utilization of residual heat and poor matching of cold / heat energy, hindering the commercialization of this technology. In particular, the mismatch in flow rates during the heat exchange process between the hot lean solution and the cold rich solution leads to significant sensible heat loss in the hot lean solution and insufficient utilization of its residual heat. At the same time, the reaction heat released during CO2 absorption requires a large amount of cooling water to cool the absorption tower to increase mass transfer efficiency, resulting in substantial loss of reaction heat. This, in turn, leads to high energy consumption during carbon dioxide desorption and high cooling water consumption in the system.

[0004] Furthermore, the recovery of high-grade and low-grade waste heat is not targeted, and the recovery of low-grade waste heat from absorption reactions and waste heat from lean liquor in the medium-temperature section is not sufficiently improved, resulting in inadequate utilization of waste heat. This also leads to high energy consumption during the carbon dioxide desorption process and high cooling water consumption in the system. Summary of the Invention

[0005] In view of the above problems, the present invention proposes a heat pump-based carbon dioxide capture system for recovering waste heat, which overcomes or at least partially solves the above problems.

[0006] One object of the present invention is to make full use of low-grade waste heat.

[0007] Another objective of this invention is to fully utilize the waste heat and reaction heat of the lean liquid in the carbon capture system.

[0008] Another objective of this invention is to significantly reduce cooling water consumption during carbon dioxide capture, thereby further reducing carbon capture operating costs.

[0009] In particular, according to one aspect of the present invention, a carbon dioxide capture system is provided, comprising: an absorption tower, a rich-lean liquid heat exchanger, and a desorption tower, wherein the cold rich liquid inlet, hot rich liquid outlet, hot lean liquid inlet, and cold lean liquid outlet of the rich-lean liquid heat exchanger are respectively connected via pipelines to the rich liquid outlet of the absorption tower, the first rich liquid inlet of the desorption tower, the hot lean liquid outlet of the desorption tower, and the lean liquid inlet of the absorption tower; wherein the carbon dioxide capture system further comprises:

[0010] The second diverter, installed in the pipeline between the rich liquid outlet of the absorption tower and the cold rich liquid inlet of the lean-rich liquid heat exchanger, is configured to divert the rich liquid output from the absorption tower; and

[0011] At least one of the first heat pump waste heat recovery and utilization unit and the third heat pump waste heat recovery and utilization unit; wherein

[0012] The first heat pump type waste heat recovery and utilization component includes:

[0013] The first waste heat recovery heat pump includes a first waste heat recovery heat exchanger in a pipeline between the cold lean liquid outlet of the lean and rich liquid heat exchanger and the lean liquid inlet of the absorption tower. The first waste heat recovery heat pump is configured to recover the waste heat of the lean liquid by exchanging heat between the first heat pump working fluid and the lean liquid in the first waste heat recovery heat exchanger.

[0014] The first waste heat utilization device, connected to the working fluid loop of the first waste heat recovery heat pump and connected to the bottom of the desorption tower, is configured to use the recovered lean liquor waste heat to heat the medium-lean liquor at the bottom of the desorption tower through heat exchange for carbon dioxide desorption; and

[0015] The first coupling heat exchanger is connected to the working fluid loop of the first waste heat recovery heat pump and is located downstream of the first waste heat utilization device. It is connected to the second distributor and the second rich liquid inlet of the desorption tower respectively. It is configured to allow the working fluid output from the first waste heat utilization device to exchange heat with a rich liquid branched out by the second distributor, and to output the rich liquid after heat exchange to the second rich liquid inlet of the desorption tower.

[0016] The third heat pump type waste heat recovery and utilization component includes:

[0017] The third waste heat recovery heat pump includes a fourth waste heat recovery heat exchanger disposed between the absorbent outlet and the absorbent return outlet of the absorption tower. The third waste heat recovery heat pump is configured to recover the waste heat of the absorption reaction of the absorption tower by exchanging heat between the fourth heat pump working fluid and the absorbent drawn from the absorption tower in the fourth waste heat recovery heat exchanger.

[0018] The third waste heat utilization device, connected to the working fluid loop of the third waste heat recovery heat pump and connected to the bottom of the desorption tower, is configured to use the recovered waste heat from the absorption reaction to heat the lean liquid at the bottom of the desorption tower through heat exchange for carbon dioxide desorption; and

[0019] The second coupling heat exchanger is connected to the working fluid loop of the third waste heat recovery heat pump and is located downstream of the third waste heat utilization device. It is connected to the second distributor and the third rich liquid inlet of the desorption tower, respectively. It is configured to allow the working fluid output from the third waste heat utilization device to exchange heat with a rich liquid branched out by the second distributor, and to output the rich liquid after heat exchange to the third rich liquid inlet of the desorption tower.

[0020] Optionally, the carbon dioxide capture system includes a first heat pump-type waste heat recovery and utilization component, and further includes:

[0021] The first diverter is installed in the pipeline between the hot lean liquid outlet of the desorption tower and the hot lean liquid inlet of the lean-rich liquid heat exchanger, and is configured to divert the hot lean liquid output from the desorption tower; and

[0022] The second heat pump type waste heat recovery and utilization component includes:

[0023] A second waste heat recovery heat pump includes a second waste heat recovery heat exchanger disposed between a first distributor and a first waste heat recovery heat exchanger. The second waste heat recovery heat exchanger is configured to allow the working fluid of the second heat pump to exchange heat with a lean liquid from the distributor to absorb heat, and to output the lean liquid after heat exchange to the first waste heat recovery heat exchanger.

[0024] The second waste heat utilization device is connected to the working fluid loop of the second waste heat recovery heat pump and is connected to the bottom of the desorption tower. It is configured to use the heat of the working fluid of the second heat pump to heat the medium-lean liquid at the bottom of the desorption tower through heat exchange for carbon dioxide desorption.

[0025] In the carbon dioxide capture system provided by this invention, a first waste heat recovery heat pump is used to recover and upgrade the waste heat of the lean liquid in the medium temperature range after it has been cooled by the lean-rich liquid heat exchanger, and / or a third waste heat recovery heat pump is used to recover and upgrade the reaction waste heat of the absorbent liquid. The recovered waste heat is then used to heat the medium-lean liquid at the bottom of the desorption tower for carbon dioxide desorption, thereby achieving the recovery and full upgrading of low-grade waste heat and making full use of low-grade waste heat.

[0026] Meanwhile, in the carbon dioxide capture system provided by the present invention, the heat energy recovered from the lean solution in the mid-temperature section is reused by the first coupling heat exchanger to further exchange heat with the working fluid after carbon dioxide desorption and the diverted cold rich solution to preheat the cold rich solution, and / or the heat energy of the recovered absorbent reaction is reused by the second coupling heat exchanger to further exchange heat with the diverted cold rich solution to preheat the cold rich solution, thereby realizing the coupled utilization of energy within the carbon dioxide capture system and effectively reducing the heat consumption and operating cost of the carbon dioxide capture system.

[0027] Furthermore, the hot lean liquor output from the desorption tower is diverted through the first distributor, and the hot lean liquor in the high-temperature section and the lean liquor in the medium-temperature section after being cooled by the lean-rich liquor heat exchanger are respectively recovered through the second waste heat recovery heat pump and the first waste heat recovery heat pump. The recovered waste heat is then used to heat the medium-lean liquor at the bottom of the desorption tower for carbon dioxide desorption, thereby realizing the cascade utilization of the lean liquor waste heat and achieving the goal of fully utilizing the lean liquor waste heat.

[0028] Furthermore, the carbon dioxide capture system provided by this invention also recovers the reaction waste heat of the absorbent through a third waste heat recovery heat exchanger or a third waste heat recovery heat pump. At the same time, while recovering the waste heat of the lean liquid and the reaction waste heat of the absorbent, the working fluid replaces the traditional cooling water to achieve the cooling function of the lean liquid and absorbent, thereby significantly reducing the cooling water consumption during the carbon dioxide capture process and further reducing the carbon capture operation cost.

[0029] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below.

[0030] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0031] To more clearly illustrate the technical solution of the present invention, some embodiments of the present invention will be described below with reference to the accompanying drawings. Those skilled in the art should understand that the same reference numerals may indicate the same or similar parts or components in different drawings; the drawings of the present invention are not necessarily drawn to scale. In the drawings:

[0032] Figure 1 is a schematic structural block diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0033] Figure 2 is a schematic structural block diagram of a carbon dioxide capture system according to another embodiment of the present invention;

[0034] Figure 3 is a schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0035] Figure 4 is a schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0036] Figure 5 is a partial structural schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0037] Figure 6 is a schematic diagram of a third or fourth waste heat recovery heat exchanger using multi-stage parallel sub-heat exchangers according to an embodiment of the present invention.

[0038] Figure 7 is a schematic diagram of a third or fourth waste heat recovery heat exchanger using multi-stage series sub-heat exchangers according to an embodiment of the present invention.

[0039] Figure 8 is a schematic structural block diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0040] Figure 9 is a schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0041] Figure 10 is a schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0042] Figure 11 is a schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0043] Figure 12 is a partial structural schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0044] Figure 13 is a schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0045] Figure 14 is a schematic diagram of a regenerated gas compression device employing multi-stage compression and a corresponding waste heat recovery heat exchanger employing multi-stage parallel interstage heat exchangers according to an embodiment of the present invention.

[0046] Figure 15 is a schematic diagram of a regenerated gas compression device employing multi-stage compression and a corresponding waste heat recovery heat exchanger employing multi-stage series interstage heat exchangers according to an embodiment of the present invention.

[0047] Figure 16 is a schematic structural block diagram of a heat pump type regenerative waste heat utilization module according to an embodiment of the present invention;

[0048] Figure 17 is a schematic structural block diagram of a heat pump type regenerative waste heat utilization module according to another embodiment of the present invention;

[0049] Figure 18 is a schematic diagram of a heat pump type regenerative waste heat utilization module according to an embodiment of the present invention.

[0050] Figure 19 is a schematic diagram of the structure of a heat pump type regenerative waste heat utilization module according to another embodiment of the present invention;

[0051] Figure 20 is a schematic diagram of the structure of a heat pump type regenerative waste heat utilization module according to another embodiment of the present invention;

[0052] Figure 21 is a schematic diagram of the structure of various waste heat utilization devices according to an embodiment of the present invention;

[0053] Figure 22 is a schematic diagram of the structure of various waste heat utilization devices according to another embodiment of the present invention;

[0054] Figure 23 is a schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0055] Figure 24 is a schematic diagram of a carbon dioxide capture system according to an embodiment of the present invention;

[0056] Figure 25 is a comparison of the changes in the heat of reaction of CO2 before and after introducing metal ions into the organic amine absorbent according to an embodiment of the present invention. Detailed Implementation

[0057] Those skilled in the art should understand that the embodiments described below are merely a part of the embodiments of the present invention, and not all of the embodiments of the present invention. These partial embodiments are intended to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Based on the embodiments provided by the present invention, all other embodiments obtained by those skilled in the art without creative effort should still fall within the scope of protection of the present invention.

[0058] Furthermore, one or more examples of embodiments of the invention are illustrated in the accompanying drawings. Each example is provided by way of explanation and is not intended to limit the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made to the invention without departing from the scope or spirit of the invention. For example, features shown or described as part of one embodiment may be used with another embodiment to produce yet another embodiment.

[0059] It should be noted that in the description of this invention, terms such as "center," "upper," "lower," "top," "bottom," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate direction or positional relationships, are based on the direction or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this invention. Furthermore, terms such as "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0060] Furthermore, it should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through intermediate components, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0061] Additionally, it should be noted that, for the purpose of maintaining image clarity, some connecting lines have been omitted in several of the accompanying drawings of this application. Instead, the same letters are used to indicate that two points are actually connected. For example, in Figures 1 and 2, point A at the first waste heat utilization device 160 is actually connected to point A at the bottom of the desorption tower 130.

[0062] Figure 1 is a schematic structural block diagram of a carbon dioxide capture system 10 according to an embodiment of the present invention. Figure 2 is a schematic structural block diagram of a carbon dioxide capture system 10 according to another embodiment of the present invention.

[0063] Referring to Figure 1, the carbon dioxide capture system 10 generally includes an absorption tower 110, a lean and rich liquid heat exchanger 120, and a desorption tower 130.

[0064] Absorber 110 has a lean liquor inlet 112 and a rich liquor outlet 111 located at the bottom. Absorber 110 may also have a flue gas inlet 115 located at the bottom (as shown in Figure 3). Desorption tower 130 has a first rich liquor inlet 131 and a hot lean liquor outlet 132 located at the bottom. The first rich liquor inlet 131 is located on the body of desorption tower 130, and may be located in the middle or upper middle part of the tower body, depending on the feed temperature of the rich liquor. The cold rich liquor inlet 121, hot rich liquor outlet 122, hot lean liquor inlet 123, and cold lean liquor outlet 124 of the lean-rich liquor heat exchanger 120 are respectively connected to the rich liquor outlet 111 of absorber 110, the first rich liquor inlet 131 of desorption tower 130, the hot lean liquor outlet 132 of desorption tower 130, and the lean liquor inlet 112 of absorber 110 via pipelines.

[0065] The carbon dioxide capture system 10 also includes a first heat pump type waste heat recovery and utilization component 15, which includes a first waste heat recovery heat pump 150 and a first waste heat utilization device 160; a first splitter 200; and a second heat pump type waste heat recovery and utilization component 25, which includes a second waste heat recovery heat pump 250 and a second waste heat utilization device 260.

[0066] The first waste heat recovery heat pump 150 includes a first waste heat recovery heat exchanger 151 disposed in a pipeline between the cold lean liquid outlet 124 of the lean-rich liquid heat exchanger 120 and the lean liquid inlet 112 of the absorption tower 110. The first waste heat recovery heat pump 150 is configured to recover waste heat from the lean liquid by exchanging heat between the first heat pump working fluid and the lean liquid in the first waste heat recovery heat exchanger 151.

[0067] The first waste heat utilization device 160 is connected to the working fluid loop of the first waste heat recovery heat pump 150 and to the bottom of the desorption tower 130. It is configured to use the recovered lean liquid waste heat to heat the medium-lean liquid at the bottom of the desorption tower 130 through heat exchange for carbon dioxide desorption.

[0068] The first diverter 200 is installed in the pipeline between the hot lean liquid outlet 132 of the desorption tower 130 and the hot lean liquid inlet 123 of the lean-rich liquid heat exchanger 120, and is configured to divert the hot lean liquid output from the desorption tower 130.

[0069] The second waste heat recovery heat pump 250 includes a second waste heat recovery heat exchanger 251 disposed between the first splitter 200 and the first waste heat recovery heat exchanger 151. The second waste heat recovery heat exchanger 251 is configured to allow the second heat pump working fluid to exchange heat with a branch of lean liquid to absorb heat, and to output the lean liquid after heat exchange to the first waste heat recovery heat exchanger 151.

[0070] The second waste heat utilization device 260 is connected to the working fluid loop of the second waste heat recovery heat pump 250 and to the bottom of the desorption tower 130. It is configured to use the heat of the working fluid of the second heat pump to heat the medium and lean liquid at the bottom of the desorption tower 130 through heat exchange for carbon dioxide desorption.

[0071] In the self-heating recovery and utilization carbon dioxide capture system 10 provided in this embodiment of the invention, the hot lean liquid output from the desorption tower 130 is diverted by the first diverter 200, and the hot lean liquid in the high-temperature section and the lean liquid in the medium-temperature section after being cooled by the lean-rich liquid heat exchanger are respectively recovered by the second waste heat recovery heat pump 250 and the first waste heat recovery heat pump 150. The recovered waste heat is used to heat the medium lean liquid at the bottom of the desorption tower 130 for carbon dioxide desorption, thereby realizing the cascade utilization of the lean liquid waste heat and achieving the purpose of fully utilizing the lean liquid waste heat.

[0072] Referring to Figure 2, in some embodiments, the carbon dioxide capture system 10 may further include a second diverter 100. The desorption tower 130 also has a second rich liquid inlet 136. Similarly, the second rich liquid inlet 136 may be located in the middle or upper middle part of the tower body, depending on the feed temperature of the rich liquid passing through it.

[0073] The second diverter 100 is installed in 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 is configured to divert the rich liquid output from the absorption tower 110.

[0074] The first heat pump type waste heat recovery and utilization component 15 may further include a first coupling heat exchanger 180. The first coupling heat exchanger 180 is connected to the working fluid loop of the first waste heat recovery heat pump 150 and is located downstream of the first waste heat utilization device 160. It is connected to the second distributor 100 and the second rich liquid inlet 136 of the desorption tower 130, respectively. It is configured to allow the working fluid output from the first waste heat utilization device 160 to exchange heat with a branch of rich liquid diverted from the second distributor 100 within it, and to output the heat-exchanged rich liquid to the second rich liquid inlet 136 of the desorption tower 130. The heat-exchanged working fluid circulates in the working fluid loop of the first waste heat recovery heat pump 150.

[0075] In the self-heating recovery and utilization carbon dioxide capture system 10 provided in this embodiment of the invention, the heat energy recovered from the lean liquid in the medium temperature section is further used by the first coupling heat exchanger 180 to exchange heat with the working fluid after carbon dioxide desorption and the diverted cold rich liquid to preheat the cold rich liquid, thereby realizing the coupling utilization of energy inside the carbon dioxide capture system and effectively reducing the heat consumption and operating cost of the carbon dioxide capture system.

[0076] In some alternative embodiments, both the first waste heat recovery heat pump 150 and the second waste heat recovery heat pump 250 can be compression heat pumps. Compared with absorption heat pumps for waste heat recovery commonly used in the prior art, compression heat pumps have a higher COP.

[0077] Depending on the temperature level of the recovered waste heat and the desired temperature level, the first waste heat recovery heat pump 150 and the second waste heat recovery heat pump 250 can be selected as single-stage or multi-stage compression heat pumps.

[0078] In some alternative embodiments, since the lean liquid cooled by the lean-rich liquid heat exchanger is in the intermediate temperature range, the first waste heat recovery heat pump 150 can be a single-stage or multi-stage compression heat pump to fully upgrade the recovered waste heat. Since the diverted hot lean liquid is in the high temperature range, the second waste heat recovery heat pump 250 can be a single-stage compression heat pump, reducing equipment costs while meeting the requirements for upgrading the recovered waste heat.

[0079] Figure 3 is a schematic diagram of the structure of a carbon dioxide capture system 10 according to an embodiment of the present invention.

[0080] Referring to Figure 3, in some optional embodiments, the first waste heat recovery heat pump 150 is a two-stage compression heat pump, comprising a first heat pump unit and a second heat pump unit. The first heat pump unit includes a first waste heat recovery heat exchanger 151, a first working fluid compressor 152, a first working fluid heat exchanger 153, and a first throttle valve 154, which are sequentially connected via piping to form a first working fluid loop 157 for circulating the first heat pump working fluid. The second heat pump unit includes a first working fluid heat exchanger 153, a second working fluid compressor 155, and a second throttle valve 156, which are sequentially connected via piping to form a second working fluid loop 158 for circulating the third heat pump working fluid. A first waste heat utilization device 160 and a first coupling heat exchanger 180 are sequentially connected in the piping between the second working fluid compressor 155 and the second throttle valve 156 in the direction of flow of the third heat pump working fluid.

[0081] The first working fluid loop 157 is configured to allow the first heat pump working fluid to flow into the first waste heat recovery heat exchanger 151 in a liquid state, absorb the waste heat of the lean liquid, undergo a phase change and become steam, and then enter the first working fluid heat exchanger 153 after being compressed by the first working fluid compressor 152 to exchange heat with the liquid third heat pump working fluid. After that, it passes through the first throttling valve 154 to be throttled and cooled to become liquid again, and then flows into the first waste heat recovery heat exchanger 151.

[0082] The second working fluid loop 158 is configured to allow the third heat pump working fluid to flow into the first working fluid heat exchanger 153 in liquid form. After exchanging heat with the first heat pump working fluid, the fluid undergoes a phase change and becomes steam. After being compressed by the second working fluid compressor 155, the steam enters the first waste heat utilization device 160 to heat the lean liquid at the bottom of the desorption tower 130. Then, the steam enters the first coupling heat exchanger 180 to exchange heat with the rich liquid that is split off. After that, the steam passes through the second throttling valve 156 to be throttled and cooled to become liquid again before flowing back into the first working fluid heat exchanger 153.

[0083] In this embodiment, a two-stage compression heat pump is used to fully improve the quality of the recovered mid-temperature lean liquor waste heat.

[0084] The first and third heat pump refrigerants can be selected according to actual application requirements. In some embodiments, for example, the first heat pump refrigerant can be 1663mz, and the third heat pump refrigerant can be R245fa.

[0085] Referring again to Figure 3, in some optional embodiments, the second waste heat recovery heat pump 250 includes a second waste heat recovery heat exchanger 251, a third working fluid compressor 252, and a third throttle valve 253, which are sequentially connected via piping to form a third working fluid loop 254 for circulating the second heat pump working fluid. A second waste heat utilization device 260 is connected in the piping between the third working fluid compressor 252 and the third throttle valve 253.

[0086] The third working fluid loop 254 is configured to allow the second heat pump working fluid to flow into the second waste heat recovery heat exchanger 251 in liquid form, exchange heat with the lean liquid in the branched stream, undergo a phase change and become steam, and then be compressed by the third working fluid compressor 252 and enter the second waste heat utilization device 260 to heat the medium lean liquid at the bottom of the desorption tower 130. After that, it is throttled and cooled by the third throttling valve 253 to become liquid again, and then flows into the second waste heat recovery heat exchanger 251.

[0087] In this embodiment, a single-stage compression heat pump is used to recover the waste heat of the diverted lean liquid in a cost-effective and efficient manner at high temperatures.

[0088] The second heat pump working fluid can be selected according to the actual application requirements. In some embodiments, for example, the second heat pump working fluid can be R245fa or water.

[0089] Figure 5 is a partial structural schematic diagram of a carbon dioxide capture system 10 according to an embodiment of the present invention, wherein other components unrelated to the heat recovery of absorption reaction of the absorption tower 110 are omitted for the sake of simplicity.

[0090] Referring to Figure 5, in some optional embodiments, the carbon dioxide capture system 10 may further include a third waste heat recovery heat exchanger 641, whose absorbent inlet 351a and absorbent outlet 351b are connected to the absorbent outlet 113 and absorbent return outlet 114 of the absorption tower 110, respectively. Its working fluid inlet 351c and working fluid outlet 351d are connected in parallel with the working fluid inlet and outlet of the first waste heat recovery heat exchanger 151 to the working fluid loop of the first waste heat recovery heat pump 150, so that the first heat pump working fluid is diverted into the first waste heat recovery heat exchanger 151 and the third waste heat recovery heat exchanger 641, and the first heat pump working fluids flowing out of the first waste heat recovery heat exchanger 151 and the third waste heat recovery heat exchanger 641 are combined and circulated. The third waste heat recovery heat exchanger 641 is configured to allow heat exchange between the absorbent drawn from the absorption tower 110 and the first heat pump working fluid entering it.

[0091] In this embodiment, by integrating the third waste heat recovery heat exchanger 641 into the first waste heat recovery heat pump 150, the waste heat of lean liquor and the reaction waste heat of absorbent are recovered simultaneously through a compression heat pump. This simplifies the equipment structure, saves equipment costs, and also replaces the traditional cooling water with a working fluid to achieve the cooling function of lean liquor and absorbent, thereby significantly reducing the cooling water consumption during carbon dioxide capture and further reducing the operating cost of carbon capture.

[0092] Figure 4 is a schematic diagram of a carbon dioxide capture system 10 according to an embodiment of the present invention.

[0093] Referring to Figure 4, in some optional embodiments, the carbon dioxide capture system 10 may further include a third heat pump type waste heat recovery and utilization component 35, which includes a third waste heat recovery heat pump 350 and a third waste heat utilization device 360.

[0094] The third waste heat recovery heat pump 350 includes a fourth waste heat recovery heat exchanger 351 disposed between the absorbent outlet 113 and the absorbent return outlet 114 of the absorption tower 110. The third waste heat recovery heat pump 350 is configured to recover the waste heat from the absorption reaction of the absorption tower 110 by exchanging heat between the fourth heat pump working fluid and the absorbent drawn from the absorption tower 110 in the fourth waste heat recovery heat exchanger 351.

[0095] The third waste heat utilization device 360 ​​is connected to the working fluid loop of the third waste heat recovery heat pump 350 and is connected to the bottom of the desorption tower 130. It is configured to use the recovered waste heat from the absorption reaction to heat the medium-lean liquid at the bottom of the desorption tower 130 through heat exchange for carbon dioxide desorption.

[0096] In some further embodiments, the carbon dioxide capture system 10 may also include a second coupling heat exchanger 280. The second coupling heat exchanger 280 is connected to the working fluid loop of the third waste heat recovery heat pump 350 and is located downstream of the third waste heat utilization device 360. It is connected to the second distributor 100 and the third rich liquid inlet 137 of the desorption tower 130, respectively. It is configured to allow the working fluid output from the third waste heat utilization device 360 ​​to exchange heat with another stream of rich liquid diverted from the second distributor 100 within it, and to output the heat-exchanged rich liquid to the third rich liquid inlet 137 of the desorption tower 130. The heat-exchanged working fluid circulates within the working fluid loop of the third waste heat recovery heat pump 350.

[0097] In this embodiment, by setting up an independent third waste heat recovery heat pump 350, the reaction waste heat of the absorbent can be specifically recovered, thereby achieving efficient recovery and quality improvement of the reaction waste heat of the absorbent. At the same time, while recovering the waste heat of the lean liquid and the reaction waste heat of the absorbent, the working fluid replaces the traditional cooling water to achieve the cooling function of the lean liquid and absorbent, thereby significantly reducing the cooling water consumption during carbon dioxide capture and further reducing the operating cost of carbon capture.

[0098] In some alternative embodiments, the third waste heat recovery heat pump 350 may be a single-stage or multi-stage compression heat pump, depending on the temperature level of the recovered waste heat and the desired temperature level.

[0099] Referring again to Figure 4, in some optional embodiments, the third waste heat recovery heat pump 350 is a two-stage compression heat pump, comprising a third heat pump unit and a fourth heat pump unit. The third heat pump unit includes a fourth waste heat recovery heat exchanger 351, a fourth working fluid compressor 352, a second working fluid heat exchanger 353, and a fourth throttle valve 354, which are sequentially connected via piping to form a fourth working fluid loop 357 for the circulation of the fourth heat pump working fluid. The fourth heat pump unit includes a second working fluid heat exchanger 353, a fifth working fluid compressor 355, and a fifth throttle valve 356, which are sequentially connected via piping to form a fifth working fluid loop 358 for the circulation of the fifth heat pump working fluid. The third waste heat utilization device 360 ​​and the second coupling heat exchanger 280 are sequentially connected in the piping between the fifth working fluid compressor 355 and the fifth throttle valve 356 according to the flow direction of the fifth heat pump working fluid.

[0100] The fourth working fluid loop 357 is configured to allow the fourth heat pump working fluid to flow into the fourth waste heat recovery heat exchanger 351 in a liquid state, absorb the waste heat of the reaction, undergo a phase change and become steam, and then enter the second working fluid heat exchanger 353 after being compressed by the fourth working fluid compressor 352 to exchange heat with the liquid fifth heat pump working fluid. After that, it passes through the fourth throttling valve 354 to be throttled and cooled to become liquid again, and then flows into the fourth waste heat recovery heat exchanger 351.

[0101] The fifth working fluid loop 358 is configured to allow the fifth heat pump working fluid to flow into the second working fluid heat exchanger 353 in a liquid state and exchange heat with the fourth heat pump working fluid, after which a phase change occurs and it becomes steam. After being compressed by the fifth working fluid compressor 355, it enters the third waste heat utilization device 360 ​​to heat the lean liquid at the bottom of the desorption tower 130. Then it enters the second coupling heat exchanger 280 to exchange heat with the other rich liquid that is split off. After that, it passes through the fifth throttling valve 356 to be throttled and cooled to become liquid again, and then flows into the second working fluid heat exchanger 353.

[0102] In this embodiment, a two-stage compression heat pump is used to fully enhance the quality of the waste heat from the reaction of the recovered absorbent liquid.

[0103] The fourth and fifth heat pump working fluids can be selected according to actual application requirements. In some embodiments, for example, the fourth heat pump working fluid can be 1663mz, and the fifth heat pump working fluid can be R245fa.

[0104] It should be noted that, for the purpose of the third waste heat recovery heat exchanger 641 recovering the heat of absorption reaction within the absorption tower 110, Figure 5 shows the third waste heat recovery heat exchanger 641 as being placed inside the absorption tower 110. However, this does not mean that the third waste heat recovery heat exchanger 641 must be located inside the absorption tower 110. Those skilled in the art will understand that the third waste heat recovery heat exchanger 641 can be located outside the absorption tower 110. The absorbent in the absorption tower 110 is introduced into the third waste heat recovery heat exchanger 641 for heat exchange through the absorbent inlet 113 and absorbent return outlet 114, and then the absorbent is returned to the absorption tower 110.

[0105] In some alternative embodiments, the third waste heat recovery heat exchanger 641 or the fourth waste heat recovery heat exchanger 351 may include a plurality of sub-heat exchangers 351', which may be connected in parallel or in series. Here, "a plurality of" means two or more.

[0106] Figure 6 is a schematic diagram of a third waste heat recovery heat exchanger 641 or a fourth waste heat recovery heat exchanger 351 using multi-stage parallel sub-heat exchangers according to an embodiment of the present invention. As shown in Figure 6, when multiple sub-heat exchangers 351' are connected in parallel, the absorbent inlet 351a and absorbent outlet 351b of each sub-heat exchanger 351' are respectively connected to the corresponding absorbent outlet 113 and absorbent return outlet 114 on the absorption tower 110. The working fluid inlet 351c of each sub-heat exchanger 351' can be connected to the working fluid loop connected to the third waste heat recovery heat exchanger 641 or the fourth waste heat recovery heat exchanger 351 via pipelines to receive the incoming low-temperature liquid working fluid. The working fluid outlet 351d of each sub-heat exchanger 351' can also be connected to the working fluid loop connected to the third waste heat recovery heat exchanger 641 or the fourth waste heat recovery heat exchanger 351 to return the heat-exchanged working fluid to the working fluid loop for circulation.

[0107] Figure 7 is a schematic diagram of a third waste heat recovery heat exchanger 641 or a fourth waste heat recovery heat exchanger 351 employing multi-stage series sub-heat exchangers according to an embodiment of the present invention. As shown in Figure 7, when multiple sub-heat exchangers 351' are connected in series, the absorbent inlet 351a and absorbent outlet 351b of each sub-heat exchanger 351' are respectively connected to the corresponding absorbent outlet 113 and absorbent return port 114 on the absorption tower 110. Along the direction of working fluid flow, the working fluid inlet 351c of the first sub-heat exchanger 351' is connected via a pipeline to the working fluid loop into which the third waste heat recovery heat exchanger 641 or the fourth waste heat recovery heat exchanger 351 is connected to receive the incoming low-temperature liquid working fluid. The working fluid outlet 351d of the last sub-heat exchanger 351' is connected to the working fluid loop into which the third waste heat recovery heat exchanger 641 or the fourth waste heat recovery heat exchanger 351 is connected. The working fluid outlet 351d of each sub-heat exchanger 351' located between the first and last sub-heat exchangers is connected to the working fluid inlet 351c of the next adjacent sub-heat exchanger 351'.

[0108] Figure 21 is a schematic diagram of the structure of various waste heat utilization devices according to an embodiment of the present invention.

[0109] Referring to Figure 21, in some optional embodiments, the aforementioned first waste heat recovery device 160, second waste heat recovery device 260, and / or third waste heat recovery device 360 ​​may each include a first reboiler 171. The first reboiler 171 is configured to exchange heat between the lean liquid drawn from the bottom of the desorption tower 130 and the working fluid that has absorbed heat from the corresponding waste heat recovery heat pump for carbon dioxide desorption, and then return it to the bottom of the desorption tower 130, causing at least a partial phase change of the heat-exchanged working fluid to a liquid state, and outputting the heat-exchanged working fluid.

[0110] Specifically, the first reboiler 171 has a lean liquor inlet 171a, a lean liquor outlet 171b, a working fluid inlet 171c, and a working fluid outlet 171d. The bottom of the desorption tower 130 is provided with a lean liquor outlet 134 and a lean liquor return outlet 135. The lean liquor inlet 171a and outlet 171b of the first reboiler 171 are respectively connected to the bottom of the desorption tower 130 to receive the lean liquor flowing into and out of the desorption tower 130, respectively. The working fluid inlet 171c and outlet 171d are respectively connected to the working fluid loop of the first reboiler 171 to receive the working fluid flowing into and return the working fluid to the working fluid loop, respectively.

[0111] In this embodiment, the first reboiler 171 can be considered as a condenser. It uses lean carbon dioxide solution drawn from the bottom of the desorption tower 13 as a condensing medium to exchange heat with the high-temperature compressed working fluid vapor. The lean solution directly absorbs the heat released by the compressed working fluid vapor for carbon dioxide desorption, while the compressed working fluid vapor cools and condenses. Thus, the reboiler and working fluid condenser are combined into one unit, simplifying the structure, reducing the number of devices, and lowering system equipment costs while efficiently utilizing and recovering waste heat.

[0112] Figure 22 is a schematic diagram of the structure of various waste heat utilization devices according to another embodiment of the present invention.

[0113] Referring to Figure 22, in some alternative embodiments, the aforementioned first waste heat utilization device 160, second waste heat utilization device 260, and / or third waste heat utilization device 360 ​​may each include a second reboiler 172 and a condenser heat exchanger 174. The condenser heat exchanger 174 is connected to the working fluid loop of the corresponding waste heat recovery heat pump containing the waste heat utilization device, and is configured to allow the condensate entering the condenser heat exchanger 174 to exchange heat with the compressed working fluid vapor to generate water vapor, and to condense at least partially the compressed working fluid vapor after heat exchange into a liquid working fluid, and output the heat-exchanged working fluid. The second reboiler 172 is connected to the bottom of the desorption tower 130 and the condenser heat exchanger 174 respectively, and is configured to allow the lean liquid drawn from the bottom of the desorption tower 130 to exchange heat with the water vapor from the condenser heat exchanger 174 to perform carbon dioxide desorption, and then return to the bottom of the desorption tower 130, condensing the water vapor into water and outputting it to the condenser heat exchanger 174.

[0114] Optionally, a steam compression device (not shown in the figure) can be provided between the second reboiler 172 and the condenser heat exchanger 174 to compress and heat the generated steam. The compressed and heated steam then enters the second reboiler 172.

[0115] In this embodiment, a condenser heat exchanger 174 is installed, using water as the condensing medium to exchange heat with high-temperature compressed working fluid steam to generate steam. This steam then enters the second reboiler 172 to heat the lean solution of carbon dioxide drawn from the bottom of the desorption tower 13, thereby achieving carbon dioxide desorption. This method not only efficiently utilizes the recovered waste heat but also directly utilizes the existing reboiler of the desorption tower without requiring modifications to the reboiler (such as selecting materials suitable for the working fluid) or changes to the reboiler's operating conditions and processes, thus reducing system modification costs.

[0116] In some further embodiments, continuing to refer to FIG22, the aforementioned first waste heat utilization device 160, second waste heat utilization device 260, and / or third waste heat utilization device 360 ​​may each further include a flash evaporator 173 connected between the second reboiler 172 and the condenser heat exchanger 174. The second reboiler 172 has a lean liquid inlet 172a, a lean liquid outlet 172b, a steam inlet 172c, and a condensate outlet 172d. The flash evaporator 173 has a fluid inlet 173a, a liquid outlet 173b, and a steam outlet 173c. The condenser heat exchanger 174 has a working fluid inlet 174a, a working fluid outlet 174b, a condensate inlet 174c, and a fluid outlet 174d.

[0117] The working fluid inlet 174a and working fluid outlet 174b of the condensing heat exchanger 174 are respectively connected to the working fluid loop of the corresponding waste heat recovery heat pump where the waste heat utilization device is located. The condensing heat exchanger 174 is configured to allow the condensate entering the condensing heat exchanger 174 to exchange heat with the incoming compressed working fluid vapor to generate a high-temperature fluid (high-temperature water, water vapor, or a mixture of both), and to condense at least partially the compressed working fluid after heat exchange into a liquid working fluid, which is then output through the working fluid 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 condensate inlet 174c of the condensing heat exchanger 174. 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 produced in flash evaporator 173 is output to condenser heat exchanger 174 via liquid outlet 173b and condensate inlet 174c. The lean liquid inlet 172a, lean liquid outlet 172b, steam inlet 172c, and condensate outlet 172d of the second reboiler 172 are respectively connected to the lean liquid outlet and lean liquid return port at the bottom of desorption tower 130, the steam outlet 173c of flash evaporator 173, and the condensate inlet 174c of condenser heat exchanger 174. The second reboiler 172 is configured to allow the lean liquid drawn from the bottom of desorption tower 130 to exchange heat with the steam from flash evaporator 173 for carbon dioxide desorption, and then return to the bottom of desorption tower, while condensing the steam into condensate and outputting it to condenser heat exchanger 174.

[0118] Optionally, a steam compression device (not shown in the figure) can be provided between the second reboiler 172 and the flash evaporator 173 to compress and heat the generated steam. The compressed and heated steam then enters the second reboiler 172.

[0119] In this embodiment, the high-temperature fluid generated by the condenser heat exchanger 174 is flashed using the flash evaporator 173, which further improves the quality of the generated water vapor and thus further improves the utilization efficiency of waste heat recovery.

[0120] In embodiments of the present invention, the second diverter 100 and the first diverter 200 can employ various diversion devices, such as multi-way diverter valves. In some embodiments, different combinations of diversion devices can be used depending on the number of rich or lean liquid flow paths ultimately diverted. For example, as shown in Figure 4, if it is necessary to divide the rich liquid into four rich liquid diversion paths, two three-way valves 100 can be combined as diverters. The specific diverters 100 and 200 can be selected and combined according to actual application requirements, and the present invention does not impose specific limitations on this.

[0121] In some optional embodiments, a fourth rich liquid inlet 138 is provided at the top of the desorption tower 130. The fourth rich liquid inlet 138 is connected to one outlet of the distributor 100, so that one stream of rich liquid flowing out of the distributor 100 directly enters the desorption tower 130 through the fourth rich liquid inlet 138. In this embodiment, by diverting a portion of the carbon dioxide rich liquid flowing out from the bottom of the absorption tower 110 directly into the desorption tower 130, energy recovery is performed inside the desorption tower, thereby further improving the energy recovery and utilization efficiency.

[0122] In some optional embodiments, the desorption tower 130 also includes a regeneration gas outlet 133 located at the top. The carbon dioxide capture system 10 may also include a regeneration gas cooler 190 and a gas-liquid separator 191 sequentially connected to the regeneration gas outlet 133. The liquid outlet of the gas-liquid separator 191 is connected to the return liquid port at the top of the desorption tower 130. The carbon dioxide regeneration gas flowing out of the regeneration gas outlet 133 enters the regeneration gas cooler 190 for condensation, and then enters the gas-liquid separator 191 for gas-liquid separation. The condensed and separated liquid is returned to the desorption tower 130 from the return liquid port.

[0123] In some alternative embodiments, the carbon dioxide capture system 10 may further include a fourth heat pump waste heat recovery and utilization component 45. The fourth heat pump waste heat recovery and utilization component 45, together with the desorption tower 130 and the regenerated gas compression device 140, constitutes a heat pump regenerated waste heat utilization module 600. The fourth heat pump waste heat recovery and utilization component 45 and the heat pump regenerated waste heat utilization module 600 will be described later.

[0124] In some embodiments, the structure of the carbon dioxide capture system 10, including the fourth heat pump waste heat recovery and utilization component 45, is shown in FIG24, for example.

[0125] In some embodiments of the present invention, an absorbent is provided. This absorbent is a CO2 composite absorbent comprising a cyclic organic amine, a sterically hindered amine, a metal complexing agent, and water. This CO2 composite absorbent is suitable for a carbon dioxide capture system 10 that performs self-heating recovery and reuse of the hot lean liquid output from the desorption tower 130 after being diverted by a first diverter 200.

[0126] In some embodiments, the total mass percentage of the cyclic organic amine, the sterically hindered amine, and the metal complexing agent in the compound absorbent may be 20-60%, for example 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%.

[0127] In some preferred embodiments, the total mass ratio of cyclic organic amines, sterically hindered amines, and metal complexing agents in the compound absorbent can be 30-40%.

[0128] In some specific embodiments, the CO2 compound absorbent comprises, by weight: 8-25% cyclic organic amine, 10-35% sterically hindered amine, 0.1-2.0% metal complexing agent, and the balance being water.

[0129] In some more specific embodiments, the mass percentage of cyclic organic amines in the CO2 composite absorbent can be 10%, 12%, 15%, 18%, 20%, 22%, etc.

[0130] In some more specific embodiments, the mass percentage of sterically hindered amine in the CO2 composite absorbent can be 12%, 15%, 18%, 20%, 22%, 25%, 27%, 30%, 33%, etc.

[0131] In some more specific embodiments, the mass ratio of the metal complexing agent in the CO2 composite absorbent can be 0.3%, 0.5%, 0.7%, 1.0%, 1.2%, 1.5%, 1.8%, etc.

[0132] In some alternative embodiments, the cyclic organic amine may be one or more of piperazine, N-hydroxyethylpiperazine, 1-(2-hydroxyethyl)-4-aminopiperidine, 4-hydroxy-1-methylpiperidine, 3-aminomethylpyridine, N-aminoethylpiperazine, and aniline.

[0133] In some alternative embodiments, the sterically hindered amine may be one or more of 2-amino-2-methyl-1-propanol, isopropanolamine, sodium aminoisobutyrate, and 2-amino-2-ethyl-1,3-propanediol.

[0134] In some alternative embodiments, the metal complexing agent may be one of ethylenediaminetetraacetic acid, tartaric acid tetrahydrate, or a mixture thereof.

[0135] The carbon capture performance of different absorbent formulations is compared below, see Table 1 for details.

[0136] Table 1

[0137] All proportions in Table 1 are mass proportions, and each formulation contains 0.5% ethylenediaminetetraacetic acid and 0.5% tartaric acid tetrahydrate. Saturated CO2 loading was determined by bubbling at a CO2 volume concentration of 10%; the average CO2 absorption rate was determined by bubbling at a CO2 volume concentration of 10%, with the CO2 concentration at the outlet monitored in real time during the experiment; the CO2 reaction heat was determined by Joule heat using a C80 microcalorimeter, and the average CO2 reaction heat was obtained by integration; the desorption temperature was obtained by Aspen Plus simulation at 2 bar; the desorption energy consumption was obtained by calculation of reaction heat, sensible heat, and latent heat. The sensible heat was obtained by Aspen Plus simulation at 5 K in a lean-rich liquid heat exchanger, and the latent heat was calculated by Aspen Plus simulation under optimized rich liquid splitting conditions based on temperature and the molar ratio of CO2 / H2O.

[0138] As shown in Table 1, the composite absorbent of cyclic organic amines and sterically hindered amines outperforms the benchmark ethanolamine absorbent in key performance aspects such as CO2 loading, CO2 absorption rate, CO2 reaction heat, and desorption energy consumption. This is because cyclic organic amines contain a polyamine structure, resulting in a significantly higher concentration of amine groups per molar molecule compared to monoethanolamines, thus increasing the CO2 absorption rate and capacity. Simultaneously, sterically hindered amines, by accepting protons, theoretically double the CO2 absorption capacity compared to monoethanolamines. Therefore, this composite absorbent increases the CO2 absorption capacity and absorption rate per unit mass of solvent, while reducing the CO2 reaction heat and the desorption temperature and heat consumption during solvent regeneration. In this invention, coupling with a heat pump process reduces the temperature difference between the cold and hot ends, improves the heat pump COP performance, reduces the heat pump load and electrical efficiency, and overall enhances the energy utilization efficiency of the carbon capture system.

[0139] Furthermore, in some implementation cases, antioxidants, corrosion inhibitors, and antifoaming agents are added to the absorbent to enhance its long-term stable operation performance.

[0140] Specifically, by mass, the absorbent contains 0.1-1% antioxidants, such as 0.2%, 0.4%, 0.5%, 0.7%, 0.9%, etc.; the absorbent contains 0.1-1% corrosion inhibitors, such as 0.2%, 0.4%, 0.5%, 0.7%, 0.9%, etc.; and the absorbent contains 0.01-0.1% antifoaming agents, such as 0.02%, 0.03%, 0.05%, 0.06%, 0.08%, etc.

[0141] In some specific embodiments, the antioxidant is one or a mixture of sodium metavanadate, potassium bismuth citrate, and sodium antimony gluconate. The corrosion inhibitor is one or a mixture of sodium molybdate, sodium tungstate, thiourea, sodium vanadate, potassium orthophosphate, sodium borate, and diethanolglycine. The antifoaming agent is dimethyl silicone oil, polypropylene glycol, or a mixture thereof.

[0142] Figure 8 is a schematic structural block diagram of a carbon dioxide capture system 10 according to an embodiment of the present invention, wherein the carbon dioxide capture system 10 uses a heat pump to recover and utilize waste heat.

[0143] Referring to Figure 8, the carbon dioxide capture system 10 generally includes an absorption tower 110, a lean and rich liquid heat exchanger 120, and a desorption tower 130.

[0144] Absorber 110 has a lean liquor inlet 112 and a rich liquor outlet 111 located at the bottom. Absorber 110 may also have a flue gas inlet 115 located at the bottom (as shown in Figure 3). Desorption tower 130 has a first rich liquor inlet 131 and a hot lean liquor outlet 132 located at the bottom. The first rich liquor inlet 131 is located on the body of desorption tower 130, and may be located in the middle or upper middle part of the tower body, depending on the feed temperature of the rich liquor. The cold rich liquor inlet 121, hot rich liquor outlet 122, hot lean liquor inlet 123, and cold lean liquor outlet 124 of the lean-rich liquor heat exchanger 120 are respectively connected to the rich liquor outlet 111 of absorber 110, the first rich liquor inlet 131 of desorption tower 130, the hot lean liquor outlet 132 of desorption tower 130, and the lean liquor inlet 112 of absorber 110 via pipelines.

[0145] The carbon dioxide capture system 10 further includes: a second diverter 100 disposed in a 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, configured to divert the rich liquid output from the absorption tower 110; and at least one of a first heat pump type waste heat recovery and utilization component 15 and a third heat pump type waste heat recovery and utilization component 35.

[0146] The first heat pump type waste heat recovery and utilization component 15 may include a first waste heat recovery heat pump 150, a first waste heat utilization device 160, and a first coupling heat exchanger 180.

[0147] The first waste heat recovery heat pump 150 includes a first waste heat recovery heat exchanger 151 disposed in a pipeline between the cold lean liquid outlet 124 of the lean-rich liquid heat exchanger 120 and the lean liquid inlet 112 of the absorption tower 110. The first waste heat recovery heat pump 150 is configured to recover waste heat from the lean liquid by exchanging heat between the first heat pump working fluid and the lean liquid in the first waste heat recovery heat exchanger 151.

[0148] The first waste heat utilization device 160 is connected to the working fluid loop of the first waste heat recovery heat pump 150 and to the bottom of the desorption tower 130. It is configured to use the recovered lean liquid waste heat to heat the medium-lean liquid at the bottom of the desorption tower 130 through heat exchange for carbon dioxide desorption.

[0149] The first coupling heat exchanger 180 is connected to the working fluid loop of the first waste heat recovery heat pump 150 and is located downstream of the first waste heat utilization device 160. It is connected to the second rich liquid inlet 136 of the second distributor 100 and the desorption tower 130, respectively. It is configured to allow the working fluid output from the first waste heat utilization device 160 to exchange heat with a rich liquid branched out from the second distributor 100, and to output the heat-exchanged rich liquid to the second rich liquid inlet 136 of the desorption tower 130.

[0150] The third heat pump type waste heat recovery and utilization component 35 includes a third waste heat recovery heat pump 350, a third waste heat utilization device 360, and a second coupling heat exchanger 280.

[0151] The third waste heat recovery heat pump 350 includes a fourth waste heat recovery heat exchanger 351 disposed between the absorbent inlet and the absorbent return outlet of the absorption tower 110. The third waste heat recovery heat pump 350 is configured to recover the waste heat from the absorption reaction of the absorption tower 110 by exchanging heat between the fourth heat pump working fluid and the absorbent drawn from the absorption tower 110 in the fourth waste heat recovery heat exchanger 351.

[0152] The third waste heat utilization device 360 ​​is connected to the working fluid loop of the third waste heat recovery heat pump 350 and is connected to the bottom of the desorption tower 130. It is configured to use the recovered waste heat from the absorption reaction to heat the medium-lean liquid at the bottom of the desorption tower 130 through heat exchange for carbon dioxide desorption.

[0153] The second coupling heat exchanger 280 is connected to the working fluid loop of the third waste heat recovery heat pump 350 and is located downstream of the third waste heat utilization device 360. It is connected to the third rich liquid inlet 137 of the second distributor 100 and the desorption tower 130, respectively. It is configured to allow the working fluid output from the third waste heat utilization device 360 ​​to exchange heat with a rich liquid branched out from the second distributor 100 within it, and to output the heat-exchanged rich liquid to the third rich liquid inlet 137 of the desorption tower 130.

[0154] In this embodiment, the first heat pump type waste heat recovery and utilization component 15 and / or the third heat pump type waste heat recovery and utilization component 35 are used to recover and upgrade the waste heat of the lean liquid and / or the reaction waste heat of the absorbent liquid in the medium temperature range after being cooled by the lean-rich liquid heat exchanger in the carbon dioxide capture system, thereby improving the energy efficiency of the system. At the same time, the remaining energy recovered after carbon dioxide desorption is fully utilized by the coupling heat exchanger to preheat the diverted cold rich liquid, realizing the coupled utilization of energy within the carbon dioxide capture system, effectively reducing the heat consumption and operating cost of the carbon dioxide capture system.

[0155] It should be noted that Figure 8 only illustrates the first heat pump waste heat recovery component 15 and the third heat pump waste heat recovery component 35 as examples, and does not indicate that the carbon dioxide capture system 10 must simultaneously include both the first heat pump waste heat recovery component 15 and the third heat pump waste heat recovery component 35. Those skilled in the art should recognize that the carbon dioxide capture system 10 may include only either the first heat pump waste heat recovery component 15 or the third heat pump waste heat recovery component 35.

[0156] In some alternative embodiments, the first waste heat recovery heat pump 150 may be a single-stage or multi-stage compression heat pump.

[0157] Figure 9 is a schematic diagram of the structure of a carbon dioxide capture system 10 according to an embodiment of the present invention.

[0158] Referring to Figure 9, in some embodiments, the first waste heat recovery heat pump 150 is a two-stage compression heat pump. The first waste heat recovery heat pump 150 includes a first heat pump unit and a second heat pump unit. The first heat pump unit includes a first waste heat recovery heat exchanger 151, a first working fluid compressor 152, a first working fluid heat exchanger 153, and a first throttle valve 154, which are sequentially connected via piping to form a first working fluid loop 157 for circulating the first heat pump working fluid. The second heat pump unit includes a first working fluid heat exchanger 153, a second working fluid compressor 155, and a second throttle valve 156, which are sequentially connected via piping to form a second working fluid loop 158 for circulating the third heat pump working fluid.

[0159] The first waste heat utilization device 160 and the first coupling heat exchanger 180 are connected sequentially in the pipeline between the second working fluid compressor 155 and the second throttle valve 153 according to the flow direction of the third heat pump working fluid.

[0160] The first working fluid loop 157 is configured to allow the first heat pump working fluid to flow into the first waste heat recovery heat exchanger 151 in a liquid state, absorb the waste heat of the lean liquid, undergo a phase change and become steam, and then enter the first working fluid heat exchanger 153 after being compressed by the first working fluid compressor 152 to exchange heat with the liquid third heat pump working fluid. After that, it passes through the first throttling valve 154 to be throttled and cooled to become liquid again, and then flows into the first waste heat recovery heat exchanger 151.

[0161] The second working fluid loop 158 is configured to allow the third heat pump working fluid to flow into the first working fluid heat exchanger 153 in liquid form. After exchanging heat with the first heat pump working fluid, the fluid undergoes a phase change and becomes steam. After being compressed by the second working fluid compressor 155, the steam enters the first waste heat utilization device 160 to heat the lean liquid at the bottom of the desorption tower 130. Then, the steam enters the first coupling heat exchanger 180 to exchange heat with the rich liquid that is split off. After that, the steam passes through the second throttling valve 156 to be throttled and cooled to become liquid again before flowing back into the first working fluid heat exchanger 153.

[0162] In this embodiment, a two-stage compression heat pump is used to fully improve the quality of the recovered mid-temperature lean liquor waste heat.

[0163] In some alternative embodiments, the third waste heat recovery heat pump 350 may be a single-stage or multi-stage compression heat pump.

[0164] Figure 13 is a schematic diagram of the structure of a carbon dioxide capture system 10 according to an embodiment of the present invention.

[0165] Referring to Figure 13, in some embodiments, the third waste heat recovery heat pump 350 is a two-stage compression heat pump, including a third heat pump unit and a fourth heat pump unit. The third heat pump unit includes a fourth waste heat recovery heat exchanger 351, a fourth working fluid compressor 352, a second working fluid heat exchanger 353, and a fourth throttle valve 354, which are sequentially connected via piping to form a fourth working fluid loop 357 for the circulation of the fourth heat pump working fluid. The fourth heat pump unit includes a second working fluid heat exchanger 353, a fifth working fluid compressor 355, and a fifth throttle valve 356, which are sequentially connected via piping to form a fifth working fluid loop 358 for the circulation of the fifth heat pump working fluid.

[0166] The third waste heat utilization device 360 ​​and the second coupling heat exchanger 280 are connected sequentially in the pipeline between the fifth working fluid compressor 355 and the fifth throttle valve 356 according to the flow direction of the fifth heat pump working fluid.

[0167] The fourth working fluid loop 357 is configured to allow the fourth heat pump working fluid to flow into the fourth waste heat recovery heat exchanger 351 in a liquid state, absorb the waste heat of the reaction, undergo a phase change and become steam, and then enter the second working fluid heat exchanger 353 after being compressed by the fourth working fluid compressor 352 to exchange heat with the liquid fifth heat pump working fluid. After that, it passes through the fourth throttling valve 354 to be throttled and cooled to become liquid again, and then flows into the fourth waste heat recovery heat exchanger 351.

[0168] The fifth working fluid loop 358 is configured to allow the fifth heat pump working fluid to flow into the second working fluid heat exchanger 353 in a liquid state and exchange heat with the fourth heat pump working fluid, after which a phase change occurs and it becomes steam. After being compressed by the fifth working fluid compressor 355, it enters the third waste heat utilization device 360 ​​to heat the lean liquid at the bottom of the desorption tower 130. Then it enters the second coupling heat exchanger 280 to exchange heat with the other rich liquid that is split off. After that, it passes through the fifth throttling valve 356 to be throttled and cooled to become liquid again, and then flows into the second working fluid heat exchanger 353.

[0169] In this embodiment, a two-stage compression heat pump is used to fully enhance the quality of the waste heat from the reaction of the recovered absorbent liquid.

[0170] Figure 10 is a schematic diagram of a carbon dioxide capture system 10 according to an embodiment of the present invention. Referring to Figure 10, in some embodiments, the carbon dioxide capture system 10 further includes a gas-liquid separator 191 connected via a pipeline to the regeneration gas outlet 133 of the desorption tower 130, and a regeneration gas compression device 140 connected to the gas outlet of the gas-liquid separator 191. The carbon dioxide capture system 10 may also include a fifth waste heat recovery heat exchanger 731, which is connected to the second distributor 100, the regeneration gas compression device 140, and the fifth rich liquid inlet 139 of the desorption tower 130, respectively. It is configured to allow a stream of rich liquid diverted from the second distributor 100 to exchange heat with the compressed regeneration gas generated by the regeneration gas compression device 140 within the exchanged stream, and to output the heat-exchanged rich liquid to the fifth rich liquid inlet 139.

[0171] In some alternative embodiments, the carbon dioxide capture system 10 may further include a fourth heat pump waste heat recovery and utilization component 45. The fourth heat pump waste heat recovery and utilization component 45, together with the desorption tower 130 and the regenerated gas compression device 140, constitutes a heat pump regenerated waste heat utilization module 600. The fourth heat pump waste heat recovery and utilization component 45 and the heat pump regenerated waste heat utilization module 600 will be described later.

[0172] Figure 12 is a partial structural schematic diagram of a carbon dioxide capture system 100 according to an embodiment of the present invention, wherein other components unrelated to the regeneration waste heat recovery of the desorption tower 130 are omitted for the sake of simplicity.

[0173] For example, referring to Figure 12, in some embodiments, the carbon dioxide capture system 100 further includes a gas-liquid separator 191 connected via piping to the regeneration gas outlet 133 of the desorption tower 130, and a regeneration gas compressor 140 connected to the gas outlet of the gas-liquid separator 191. The gas-liquid separator 191 is connected between the regeneration gas outlet 133 and the regeneration gas compressor 140. The liquid outlet of the gas-liquid separator 191 is connected to the return liquid port at the top of the desorption tower 130. The carbon dioxide regeneration gas flowing from the regeneration gas outlet 133 enters the gas-liquid separator 191 for gas-liquid separation. The separated liquid returns to the desorption tower 130 from the return liquid port.

[0174] The carbon dioxide capture system 100 may further include a fourth heat pump type waste heat recovery and utilization component 45. The fourth heat pump type waste heat recovery and utilization component 45 includes a fourth waste heat recovery heat pump 450 and a fourth waste heat utilization device 460. The fourth waste heat recovery heat pump 450 includes a sixth waste heat recovery heat exchanger 451 disposed in a pipeline between the regenerated gas outlet 133 of the desorption tower 130 and the gas-liquid separator 191, and a seventh waste heat recovery heat exchanger 452 connected to the regenerated gas compression device 140. The sixth waste heat recovery heat exchanger 451 is configured to allow the sixth heat pump working fluid to exchange heat with the regenerated gas output from the regenerated gas outlet 133 to recover the waste heat of the regenerated gas. The seventh waste heat recovery heat exchanger 452 is configured to allow the sixth heat pump working fluid to exchange heat with the compressed regenerated gas generated by the regenerated gas compression device 140 to recover the waste heat of the compressed regenerated gas. The fourth waste heat utilization device 460 is connected to the working fluid loop of the fourth waste heat recovery heat pump 450 and is connected to the bottom of the desorption tower 130. It is configured to use the recovered regeneration gas waste heat and compressed regeneration gas waste heat to heat the medium and lean liquid at the bottom of the desorption tower 130 through heat exchange for carbon dioxide desorption.

[0175] In some further embodiments (e.g., as shown in FIG. 19), the fourth waste heat recovery heat pump 450 is a single-stage compression heat pump, which includes a seventh waste heat recovery heat exchanger 452, a sixth waste heat recovery heat exchanger 451, a sixth working fluid compressor 453, and a sixth throttle valve 454, which are sequentially connected by piping to form a sixth working fluid loop 455 for the circulation of the sixth heat pump working fluid. The fourth waste heat utilization device 460 is connected in the piping between the sixth working fluid compressor 453 and the sixth throttle valve 454.

[0176] The sixth working fluid loop 455 is configured to allow the sixth heat pump working fluid flowing out from the sixth throttling valve 454 to flow sequentially into the seventh waste heat recovery heat exchanger 452 and the sixth waste heat recovery heat exchanger 451 in a liquid state. After exchanging heat with the compressed regenerated gas and the regenerated gas respectively, the working fluid undergoes a phase change and turns into steam. After being compressed by the sixth working fluid compressor 453, the working fluid enters the sixth waste heat utilization device 460 to heat the lean liquid at the bottom of the desorption tower 130. Afterward, it passes through the sixth throttling valve 454 to be throttled and cooled to turn into a liquid state, thereby completing the working fluid cycle.

[0177] In some further embodiments (e.g., as shown in Figure 12), the fourth waste heat recovery heat pump 450 is a single-stage compression heat pump, including a seventh waste heat recovery heat exchanger 452, a sixth waste heat recovery heat exchanger 451, a sixth working fluid compressor 453, and a sixth throttle valve 454. The seventh waste heat recovery heat exchanger 452 and the sixth waste heat recovery heat exchanger 451 are connected in parallel and then sequentially connected to the sixth working fluid compressor 453 and the sixth throttle valve 454 through pipelines to form a sixth working fluid loop 455 for circulating the working fluid of the sixth heat pump. The fourth waste heat utilization device 460 is connected in the pipeline between the sixth working fluid compressor 453 and the sixth throttle valve 454.

[0178] The sixth working fluid loop 455 is configured to allow the sixth heat pump working fluid flowing out from the sixth throttling valve 454 to be diverted in liquid form into the seventh waste heat recovery heat exchanger 452 and the sixth waste heat recovery heat exchanger 451, where it exchanges heat with the compressed regenerated gas and the regenerated gas respectively, and then undergoes a phase change to become steam. After being compressed by the sixth working fluid compressor 453, it enters the sixth waste heat utilization device 460 to heat the lean liquid at the bottom of the desorption tower 130. After that, it is throttled and cooled by the sixth throttling valve 454 to become liquid, thereby completing the working fluid cycle.

[0179] Figure 11 is a schematic diagram of a carbon dioxide capture system 10 according to an embodiment of the present invention.

[0180] In some embodiments, where a first heat pump type waste heat recovery and utilization component 15 and a third heat pump type waste heat recovery and utilization component 35 are provided in the carbon dioxide capture system 10 to correspondingly recover one of the lean liquid waste heat and the absorbent reaction waste heat, the carbon dioxide capture system 10 may further include another waste heat recovery heat exchanger for recovering the other of the lean liquid waste heat and the absorbent reaction waste heat, and the working fluid inlet and outlet of the other waste heat recovery heat exchanger are connected in parallel to the working fluid inlet and outlet of the waste heat recovery heat exchanger in the first heat pump type waste heat recovery and utilization component 15 or the third heat pump type waste heat recovery and utilization component 35 to the working fluid loop of the waste heat recovery heat pump of the first heat pump type waste heat recovery and utilization component 15 or the third heat pump type waste heat recovery and utilization component 35.

[0181] For example, as shown in Figure 11, in some embodiments, where a first heat pump type waste heat recovery and utilization component 15 is provided in the carbon dioxide capture system 10 but a third heat pump type waste heat recovery and utilization component 35 is not provided, the carbon dioxide capture system 10 may also include a third waste heat recovery heat exchanger 641. Its absorbent inlet 351a and absorbent outlet 351b are respectively connected to the absorbent outlet 113 and absorbent return port 114 of the absorption tower 110. Its working fluid inlet 351c and working fluid outlet 351d are connected to the working fluid loop of the first waste heat recovery heat pump 150 in parallel with the working fluid inlet and working fluid outlet of the first waste heat recovery heat exchanger 151, so that the first heat pump working fluid is diverted into the first waste heat recovery heat exchanger 151 and the third waste heat recovery heat exchanger 641, and the first heat pump working fluid flowing out of the first waste heat recovery heat exchanger 151 and the third waste heat recovery heat exchanger 641 is combined and circulated. The third waste heat recovery heat exchanger 641 is configured to allow the absorbent drawn from the absorption tower 110 to exchange heat with the first heat pump working fluid entering therein.

[0182] Those skilled in the art will understand that, similarly, if a third heat pump type waste heat recovery and utilization component 35 is provided in the carbon dioxide capture system 10 but the first heat pump type waste heat recovery and utilization component 15 is not provided, another waste heat recovery heat exchanger can also be provided between the lean liquid inlet 112 of the absorption tower 110 and the cold lean liquid outlet 124 of the lean and rich liquid heat exchanger 120, and this other waste heat recovery heat exchanger can be connected to the working fluid loop of the third waste heat recovery heat pump 350 in parallel with the fourth waste heat recovery heat exchanger 351.

[0183] Referring again to Figure 11, in some embodiments, the fourth heat pump waste heat recovery and utilization assembly 45 may further include a third coupling heat exchanger 380. The third coupling heat exchanger 380 is connected to the working fluid loop of the fourth waste heat recovery heat pump 450 and is located downstream of the fourth waste heat utilization device 460. It is connected to the pipeline between the second distributor 100 and the cold rich liquid inlet 121 of the lean-rich liquid heat exchanger 120. It is configured to allow the working fluid output from the fourth waste heat utilization device 450 to exchange heat with one of the rich liquids diverted from the second distributor 100, and to output the heat-exchanged rich liquid to the cold rich liquid inlet 121 of the lean-rich liquid heat exchanger 120.

[0184] In some embodiments, the fourth waste heat utilization device 460 may adopt the structure used in the first waste heat utilization device 160, the second waste heat utilization device 260 and / or the third waste heat utilization device 360 ​​described above, which will not be repeated here.

[0185] In some embodiments of the present invention, an absorbent is also provided. This absorbent is a CO2 composite absorbent comprising a cyclic organic amine, a sterically hindered amine, a soluble metal salt, and water. This CO2 composite absorbent is suitable for a carbon dioxide capture system 10 that recovers waste heat using a heat pump.

[0186] In some embodiments, the total mass percentage of cyclic organic amines, sterically hindered amines, and soluble metal salts in the compound absorbent may be 20-60%, for example 25%, 30%, 35%, 40%, 45%, 50%, 55%, or 60%.

[0187] In some preferred embodiments, the total mass proportion of cyclic organic amines, sterically hindered amines, and soluble metal salts in the compound absorbent can be 30-45%.

[0188] In some specific embodiments, the CO2 compound absorbent comprises, by weight: 10-25% cyclic organic amine, 10-35% sterically hindered amine, 3-12% soluble metal salt and the balance being water.

[0189] In some more specific embodiments, the mass percentage of cyclic organic amines in the CO2 composite absorbent can be 10%, 12%, 15%, 18%, 20%, 22%, etc.

[0190] In some more specific embodiments, the mass percentage of sterically hindered amine in the CO2 composite absorbent can be 12%, 15%, 18%, 20%, 22%, 25%, 27%, 30%, 33%, etc.

[0191] In some more specific embodiments, the mass percentage of soluble metal salts in the CO2 composite absorbent can be 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, etc.

[0192] In some alternative embodiments, the cyclic organic amine may be one or more of piperazine, N-hydroxyethylpiperazine, 1-(2-hydroxyethyl)-4-aminopiperidine, 4-hydroxy-1-methylpiperidine, 3-aminomethylpyridine, and N-aminoethylpiperazine.

[0193] In some alternative embodiments, the sterically hindered amine may be one or more of 2-amino-2-methyl-1-propanol, isopropanolamine, sodium aminoisobutyrate, and 2-amino-2-ethyl-1,3-propanediol.

[0194] In some optional embodiments, the soluble metal salt may be one or more of zinc sulfate, nickel sulfate, copper sulfate, cobalt sulfate, and manganese sulfate.

[0195] The combined absorbent of cyclic organic amines and sterically hindered amines possesses advantages such as high CO2 loading, low CO2 reaction heat, and low desorption energy consumption. This is because cyclic organic amines contain a polyamine structure, and the concentration of amine groups per molar molecule is significantly higher than that of monoethanolamines, thus increasing the CO2 absorption capacity. Steroidally hindered amines, by accepting reactant protons, theoretically double the CO2 absorption capacity compared to primary ethanolamines. Therefore, the combined absorbent increases the CO2 absorption per unit mass of solution while reducing the CO2 reaction heat and the energy consumption during solvent regeneration.

[0196] The inventors of this application also studied the change in the heat of reaction of CO2 before and after introducing metal ions into the organic amine absorbent, as shown in Figure 25.

[0197] As shown in Figure 25, introducing metal ions into the composite absorbent, based on the combination of cyclic organic amines and sterically hindered amines, further reduces the heat of reaction for CO2. This is because the metal ions form a metal-organic amine complex with the composite absorbent. This metal complex, under the influence of the CO2 acid effect, forms a chemical reaction heat buffer based on Le Chatelier dynamic equilibrium. This buffer stores the heat of reaction released during the absorption of CO2 by the organic amine in the dissociation bond energy of the metal complex. During CO2 desorption, the stored energy is released through its exothermic complexation reaction for CO2 desorption, thus recovering the heat of reaction for CO2. Taking a 12% piperazine / 28% 2-amino-2-methyl-1-propanol / 5% nickel sulfate composite absorbent as an example, the heat of reaction is reduced from 73 kJ / mol CO2 to 69 kJ / mol CO2, and the desorption energy consumption is reduced from 2.6 GJ / ton CO2 to 2.4 GJ / ton CO2. The desorption energy consumption was obtained by adding the reaction heat, sensible heat and latent heat. The sensible heat was obtained by ASPEN Plus simulation under the condition of 5K for the lean and rich liquid heat exchanger, and the latent heat was calculated by ASPEN PLUS simulation under the rich liquid split optimization condition.

[0198] Meanwhile, the Lewis acid properties of transition metal ions alter the pH of the organic amine system, promoting the conversion of carbamate to bicarbonate, thus reducing the heat of CO2 reaction and the desorption temperature. Taking a composite absorbent of 12% piperazine / 28% 2-amino-2-methyl-1-propanol / 5% nickel sulfate as an example, the desorption temperature decreased from 117℃ to 112℃ at 2 bar. This reduction in desorption temperature helps decrease the temperature difference between the cold and hot ends of the heat pump process. Using R245fa as the working fluid, the COP performance increased from 2.2 to 2.4, improving both heat pump efficiency and carbon capture energy utilization efficiency.

[0199] Embodiments of the present invention also provide a heat pump type regenerative waste heat utilization module 600 for a carbon dioxide capture system 10.

[0200] Figure 16 is a schematic structural block diagram of a heat pump type regenerative waste heat utilization module 600 according to an embodiment of the present invention.

[0201] Referring to Figure 16, the heat pump type regenerative waste heat utilization module 600 may include a desorption tower 130 having a regenerative gas outlet 133, a gas-liquid separator 191 connected to the regenerative gas outlet 133 of the desorption tower 130 via a pipeline, a regenerative gas compression device 140 connected to the gas outlet of the gas-liquid separator 191, and a fourth heat pump type waste heat recovery and utilization component 45.

[0202] Gas-liquid separator 191 is connected between regenerated gas outlet 133 and regenerated gas compression unit 140. The liquid outlet of gas-liquid separator 191 is connected to the return liquid port at the top of desorption tower 130. Carbon dioxide regenerated gas flowing from regenerated gas outlet 133 enters gas-liquid separator 191 for gas-liquid separation. The separated liquid returns to desorption tower 130 from the return liquid port.

[0203] The fourth heat pump type waste heat recovery and utilization component 45 may include a fourth waste heat recovery heat pump 450 and a fourth waste heat utilization device 460.

[0204] The fourth waste heat recovery heat pump 460 includes a sixth waste heat recovery heat exchanger 451 disposed in the pipeline between the regenerated gas outlet 133 of the desorption tower 130 and the gas-liquid separator 191, and a seventh waste heat recovery heat exchanger 452 connected to the regenerated gas compression device 140. The sixth waste heat recovery heat exchanger 451 is configured to allow the heat pump working fluid flowing through it to exchange heat with the regenerated gas output from the regenerated gas outlet 133 to recover waste heat from the regenerated gas. The seventh waste heat recovery heat exchanger 452 is configured to allow the heat pump working fluid flowing through it to exchange heat with the compressed regenerated gas generated by the regenerated gas compression device 140 to recover waste heat from the compressed regenerated gas.

[0205] The fourth waste heat utilization device 460 is correspondingly connected to the working fluid loop of the fourth waste heat recovery heat pump 450 and connected to the bottom of the desorption tower 130. It is configured to use the recovered regeneration gas waste heat and compressed regeneration gas waste heat to heat the medium and lean liquid at the bottom of the desorption tower 130 through heat exchange for carbon dioxide desorption.

[0206] The heat pump type regenerative waste heat utilization module 600 provided in this embodiment of the invention uses the fourth heat pump type waste heat recovery and utilization component 45 to efficiently recover and upgrade the waste heat of high-grade regeneration gas and compressed regeneration gas, thereby improving the energy efficiency of the system.

[0207] Figure 17 is a schematic structural block diagram of a heat pump type regenerative waste heat utilization module 600 according to another embodiment of the present invention.

[0208] Referring to Figure 17, in some optional embodiments, the fourth waste heat recovery heat pump 450 includes a regenerated gas waste heat recovery heat pump unit 550 and a compressed regenerated gas waste heat recovery heat pump unit 650, wherein the regenerated gas waste heat recovery heat pump unit 550 includes a sixth waste heat recovery heat exchanger 451 to recover regenerated gas waste heat, and the compressed regenerated gas waste heat recovery heat pump unit 650 includes a seventh waste heat recovery heat exchanger 452 to recover compressed regenerated gas waste heat.

[0209] The fourth waste heat recovery device 460 includes two independent regenerated gas waste heat recovery devices: a regenerated gas waste heat recovery device 560 and a compressed regenerated gas waste heat recovery device 660. The regenerated gas waste heat recovery device 560 is connected to the working fluid loop of the regenerated gas waste heat recovery heat pump unit 550 and to the bottom of the desorption tower 130. It is configured to use the recovered regenerated gas waste heat to heat the lean liquid at the bottom of the desorption tower 130 through heat exchange for carbon dioxide desorption. The compressed regenerated gas waste heat recovery device 660 is connected to the working fluid loop of the compressed regenerated gas waste heat recovery heat pump unit 650 and to the bottom of the desorption tower 130. It is configured to use the recovered compressed regenerated gas waste heat to heat the lean liquid at the bottom of the desorption tower 130 through heat exchange for carbon dioxide desorption.

[0210] In some further embodiments, referring to Figure 18, the regenerated gas waste heat recovery heat pump unit 550 is a single-stage compression heat pump, including a sixth waste heat recovery heat exchanger 451, a seventh working fluid compressor 552, and a seventh throttle valve 553, which are sequentially connected by pipelines to form a seventh working fluid loop 554 for circulating the seventh heat pump working fluid. A regenerated gas waste heat utilization device 560 is connected in the pipeline between the seventh working fluid compressor 552 and the seventh throttle valve 553.

[0211] The seventh working fluid loop 554 is configured to allow the seventh heat pump working fluid to flow into the sixth waste heat recovery heat exchanger 451 in liquid form, exchange heat with the regenerated gas, undergo a phase change and become steam, and then be compressed by the seventh working fluid compressor 552 and enter the regenerated gas waste heat utilization device 560 to heat the lean liquid at the bottom of the desorption tower 130. After that, it is throttled and cooled by the seventh throttling valve 553 to become liquid again and then flow into the sixth waste heat recovery heat exchanger 451.

[0212] Referring again to Figure 18, in some further embodiments, the compressed regenerated gas waste heat recovery heat pump unit 650 is a single-stage compression heat pump, including a seventh waste heat recovery heat exchanger 452, an eighth working fluid compressor 652, and an eighth throttle valve 653, which are sequentially connected via pipelines to form an eighth working fluid loop 654 for the circulation of the eighth heat pump working fluid. A compressed regenerated gas waste heat utilization device 660 is connected in the pipeline between the eighth working fluid compressor 652 and the eighth throttle valve 653.

[0213] The eighth working fluid loop 654 is configured to allow the eighth heat pump working fluid to flow into the seventh waste heat recovery heat exchanger 452 in liquid form, exchange heat with the compressed regeneration gas, undergo a phase change and become steam, and then enter the compressed regeneration gas waste heat utilization device 660 after being compressed by the eighth working fluid compressor 652 to heat the lean liquid at the bottom of the desorption tower 130. After that, it passes through the eighth throttling valve 653 to be throttled and cooled to become liquid again, and then flows into the seventh waste heat recovery heat exchanger 452.

[0214] Figure 19 is a schematic diagram of the structure of a heat pump type regenerative waste heat utilization module 600 according to another embodiment of the present invention.

[0215] Referring to Figure 19, in some optional embodiments, the heat pump working fluid flowing through the sixth waste heat recovery heat exchanger 451 and the seventh waste heat recovery heat exchanger 452 is the same sixth heat pump working fluid. The fourth waste heat recovery heat pump 450 is a single-stage compression heat pump, which includes the seventh waste heat recovery heat exchanger 452, the sixth waste heat recovery heat exchanger 451, the sixth working fluid compressor 453, and the sixth throttle valve 454, which are sequentially connected by pipelines to form a sixth working fluid loop 455 for the circulation of the sixth heat pump working fluid. The fourth waste heat utilization device 460 is connected in the pipeline between the sixth working fluid compressor 453 and the sixth throttle valve 454.

[0216] The sixth working fluid loop 455 is configured to allow the sixth heat pump working fluid flowing out from the sixth throttling valve 454 to flow sequentially into the seventh waste heat recovery heat exchanger 452 and the sixth waste heat recovery heat exchanger 451 in a liquid state. After exchanging heat with the compressed regenerated gas and the regenerated gas respectively, the working fluid undergoes a phase change and turns into steam. After being compressed by the sixth working fluid compressor 453, the working fluid enters the sixth waste heat utilization device 460 to heat the lean liquid at the bottom of the desorption tower 130. Afterward, it passes through the sixth throttling valve 454 to be throttled and cooled to turn into a liquid state, thereby completing the working fluid cycle.

[0217] Figure 20 is a structural schematic diagram of a heat pump type regenerative waste heat utilization module 600 according to another embodiment of the present invention.

[0218] Referring to Figure 20, in some optional embodiments, the heat pump working fluid flowing through the sixth waste heat recovery heat exchanger 451 and the seventh waste heat recovery heat exchanger 452 is the same sixth heat pump working fluid. The fourth waste heat recovery heat pump 450 is a single-stage compression heat pump, including the seventh waste heat recovery heat exchanger 452, the sixth waste heat recovery heat exchanger 451, the sixth working fluid compressor 453, and the sixth throttle valve 454. The seventh waste heat recovery heat exchanger 452 and the sixth waste heat recovery heat exchanger 451 are connected in parallel and then sequentially connected to the sixth working fluid compressor 453 and the sixth throttle valve 454 through pipelines to form a sixth working fluid loop 455 for the circulation of the sixth heat pump working fluid. The fourth waste heat utilization device 460 is connected in the pipeline between the sixth working fluid compressor 453 and the sixth throttle valve 454.

[0219] The sixth working fluid loop 455 is configured to allow the sixth heat pump working fluid flowing out from the sixth throttling valve 454 to be split into the seventh waste heat recovery heat exchanger 452 and the sixth waste heat recovery heat exchanger 451 in a liquid state. After exchanging heat with the compressed regenerated gas and the regenerated gas respectively, they undergo a phase change and become steam. After merging, they are compressed by the sixth working fluid compressor 453 and enter the sixth waste heat utilization device 460 to heat the lean liquid at the bottom of the desorption tower 130. Then, they are throttled and cooled by the sixth throttling valve 454 to become liquid, thus completing the working fluid cycle.

[0220] In some alternative embodiments, the regenerated gas compression device 140 may employ multi-stage compression, and accordingly, the seventh waste heat recovery heat exchanger 452 may include multiple interstage heat exchangers 851, which may be connected in parallel or in series to recover waste heat from each stage of compressed gas.

[0221] Figure 14 is a schematic diagram of a multi-stage regenerated gas compression device 140 and a seventh waste heat recovery heat exchanger 452 employing a multi-stage parallel interstage heat exchanger 851, according to an embodiment of the present invention. As shown in Figure 14, the regenerated gas compression device 140 includes multi-stage sub-compressors 140', which are connected in series to form a progressive compression structure. That is, the carbon dioxide regenerated gas adopts a multi-stage compression process.

[0222] In the case of multiple interstage heat exchangers 851 connected in parallel, the multiple interstage heat exchangers 851 and the multi-stage sub-compressors 140' are spaced apart along the flow direction of the regenerated gas. Each interstage heat exchanger 851, except the last one which is positioned along the flow direction of the compressed regenerated gas, is located between the outlet of the preceding sub-compressor 140' and the inlet of the following sub-compressor 140'. The compressed gas inlet of the last interstage heat exchanger 851 is connected to the compressed gas outlet of the last sub-compressor 140', and the compressed gas outlet can be connected to other subsequent carbon dioxide processing sections for subsequent storage and transportation. The working fluid inlet 851a of each interstage heat exchanger 851 can be connected via piping to the source component of the cryogenic liquid working fluid (e.g., a corresponding throttle valve). The working fluid outlet 851b of each interstage heat exchanger 851 can be connected to the corresponding working fluid compressor, or it can be first connected to a manifold (such as a manifold pipe, not shown in the figure), which is further connected to the corresponding working fluid compressor. The working fluid steam output from the working fluid outlet 851b of all interstage heat exchangers 851 is collected through the manifold and then delivered to the corresponding working fluid compressor.

[0223] Figure 15 is a schematic diagram of a regenerated gas compression device 140 employing multi-stage compression and a seventh waste heat recovery heat exchanger 452 employing multi-stage series interstage heat exchangers 851 according to an embodiment of the present invention. As shown in Figure 15, the regenerated gas compression device 140 includes multi-stage sub-compressors 140', which are connected in series to form a progressive compression structure.

[0224] In the case of multiple interstage heat exchangers 851 connected in series, the multiple interstage heat exchangers 851 and the multi-stage sub-compressors 140' are spaced apart along the flow direction of the regenerated gas. Each interstage heat exchanger 851, except the last one which is positioned along the flow direction of the compressed regenerated gas, is located between the outlet of the preceding sub-compressor 140' and the inlet of the following sub-compressor 140'. The compressed gas inlet of the last interstage heat exchanger 851 is connected to the compressed gas outlet of the last sub-compressor 140', and the compressed gas outlet can be connected to other subsequent carbon dioxide processing sections for subsequent storage and transportation. Along the direction of working fluid flow, the working fluid inlet 851a of the first interstage heat exchanger 851 is connected to the source component of the cryogenic liquid working fluid (e.g., a corresponding throttle valve) via a pipeline, and the working fluid outlet 851b of the last interstage heat exchanger 851 is connected to the corresponding working fluid compressor. The working fluid outlet 851b of each interstage heat exchanger 851 located between the first and last stages is connected to the working fluid inlet 851a of the next adjacent sub-heat exchanger interstage heat exchanger 851.

[0225] In some alternative embodiments, the power source for the regenerated gas compression device 140 is electrical energy or high-temperature, high-pressure gas.

[0226] In some alternative embodiments, the fourth waste heat utilization device 460, the regenerated gas waste heat utilization device 560 and / or the compressed regenerated gas waste heat utilization device 660 may adopt the structure used in the first waste heat utilization device 160, the second waste heat utilization device 260 and / or the third waste heat utilization device 360 ​​as described above, and will not be repeated here.

[0227] Figure 23 is a schematic diagram of the structure of a carbon dioxide capture system 10 according to an embodiment of the present invention.

[0228] Referring to Figure 23, in some embodiments, the carbon dioxide capture system 10 of the present invention may include an absorption tower 110, a lean-rich liquid heat exchanger 120, and the aforementioned heat pump type regenerative waste heat utilization module 600. 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 via pipelines to the rich liquid outlet 111 of the absorption tower 110, the first rich liquid inlet 131 of the desorption tower 130, the hot lean liquid outlet 132 of the desorption tower 130, and the lean liquid inlet 112 of the absorption tower 110.

[0229] Figure 24 is a schematic diagram of a carbon dioxide capture system 10 according to an embodiment of the present invention. Referring to Figure 24, in some embodiments, the carbon dioxide capture system 10 may include a first heat pump waste heat recovery and utilization component 15, a second heat pump waste heat recovery and utilization component 25, a third heat pump waste heat recovery and utilization component 35, and a fourth heat pump waste heat recovery and utilization component 45. The specific structures of these heat pump waste heat recovery and utilization components are as described above and will not be repeated here.

[0230] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0231] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A carbon dioxide capture system, comprising: The system comprises an absorption tower, a rich-lean liquid heat exchanger, and a desorption tower. The rich-lean liquid inlet, rich-hot liquid outlet, rich-hot liquid inlet, and lean-hot liquid outlet of the rich-lean liquid heat exchanger are respectively connected via pipelines to the rich liquid outlet of the absorption tower, the first rich liquid inlet of the desorption tower, the rich-hot liquid outlet of the desorption tower, and the lean liquid inlet of the absorption tower. The carbon dioxide capture system further includes: A second diverter, disposed in the pipeline between the rich liquid outlet of the absorption tower and the cold rich liquid inlet of the lean-rich liquid heat exchanger, is configured to divert the rich liquid output from the absorption tower; and At least one of the first heat pump waste heat recovery and utilization unit and the third heat pump waste heat recovery and utilization unit; wherein The first heat pump type waste heat recovery and utilization component includes: The first waste heat recovery heat pump includes a first waste heat recovery heat exchanger disposed in a pipeline between the cold lean liquid outlet of the lean and rich liquid heat exchanger and the lean liquid inlet of the absorption tower. The first waste heat recovery heat pump is configured to recover the waste heat of the lean liquid by exchanging heat between the first heat pump working fluid and the lean liquid in the first waste heat recovery heat exchanger. A first waste heat utilization device, connected to the working fluid loop of the first waste heat recovery heat pump and connected to the bottom of the desorption tower, is configured to use the recovered lean liquor waste heat to heat the medium-lean liquor at the bottom of the desorption tower through heat exchange for carbon dioxide desorption; and The first coupling heat exchanger is connected to the working fluid loop of the first waste heat recovery heat pump and is located downstream of the first waste heat utilization device. It is connected to the second distributor and the second rich liquid inlet of the desorption tower, respectively. It is configured to allow the working fluid output from the first waste heat utilization device to exchange heat with a rich liquid branched out by the second distributor, and to output the heat-exchanged rich liquid to the second rich liquid inlet of the desorption tower. The third heat pump type waste heat recovery and utilization component includes: The third waste heat recovery heat pump includes a fourth waste heat recovery heat exchanger disposed between the absorbent outlet and the absorbent return outlet of the absorption tower. The third waste heat recovery heat pump is configured to recover the waste heat of the absorption reaction of the absorption tower by exchanging heat between the fourth heat pump working fluid and the absorbent drawn from the absorption tower in the fourth waste heat recovery heat exchanger. The third waste heat utilization device, connected to the working fluid loop of the third waste heat recovery heat pump and connected to the bottom of the desorption tower, is configured to use the recovered waste heat from the absorption reaction to heat the lean liquid at the bottom of the desorption tower through heat exchange for carbon dioxide desorption; and The second coupling heat exchanger is connected to the working fluid loop of the third waste heat recovery heat pump and is located downstream of the third waste heat utilization device. It is connected to the second distributor and the third rich liquid inlet of the desorption tower, respectively. It is configured to allow the working fluid output by the third waste heat utilization device to exchange heat with a rich liquid branched out by the second distributor, and to output the heat-exchanged rich liquid to the third rich liquid inlet of the desorption tower.

2. The carbon dioxide capture system according to claim 1, wherein, The carbon dioxide capture system includes the first heat pump type waste heat recovery and utilization component; Furthermore, the carbon dioxide capture system also includes: A first diverter is disposed in the pipeline between the hot lean liquid outlet of the desorption tower and the hot lean liquid inlet of the lean-rich liquid heat exchanger, and is configured to divert the hot lean liquid output from the desorption tower; and The second heat pump type waste heat recovery and utilization component includes: A second waste heat recovery heat pump includes a second waste heat recovery heat exchanger disposed between the first distributor and the first waste heat recovery heat exchanger. The second waste heat recovery heat exchanger is configured to allow the working fluid of the second heat pump to exchange heat with a lean liquid stream from the distributor to absorb heat, and to output the lean liquid after heat exchange to the first waste heat recovery heat exchanger. The second waste heat utilization device is connected to the working fluid loop of the second waste heat recovery heat pump and is connected to the bottom of the desorption tower. It is configured to use the heat of the working fluid of the second heat pump to heat the medium-lean liquid at the bottom of the desorption tower through heat exchange for carbon dioxide desorption.

3. The carbon dioxide capture system according to claim 2, wherein, The first waste heat recovery heat pump and the third waste heat recovery heat pump are single-stage or multi-stage compression heat pumps, and the second waste heat recovery heat pump is a single-stage compression heat pump.

4. The carbon dioxide capture system according to claim 3, wherein, The first waste heat recovery heat pump is a two-stage compression heat pump, which includes a first heat pump unit and a second heat pump unit. The first heat pump unit includes a first waste heat recovery heat exchanger, a first working fluid compressor, a first working fluid heat exchanger, and a first throttle valve, which are sequentially connected by pipelines to form a first working fluid loop for the circulation of the first heat pump working fluid. The second heat pump unit includes a first working fluid heat exchanger, a second working fluid compressor, and a second throttle valve, which are sequentially connected by pipelines to form a second working fluid loop for the circulation of the third heat pump working fluid. The first waste heat recovery device and the first coupling heat exchanger are sequentially connected in the pipeline between the second working fluid compressor and the second throttling valve according to the flow direction of the third heat pump working fluid; The first working fluid loop is configured such that the first heat pump working fluid flows into the first waste heat recovery heat exchanger in liquid state to absorb the waste heat of lean liquid and undergo a phase change to become steam. After being compressed by the first working fluid compressor, it enters the first working fluid heat exchanger to exchange heat with the liquid third heat pump working fluid. Then, it passes through the first throttling valve to be throttled and cooled to become liquid again, and then flows into the first waste heat recovery heat exchanger. The second working fluid loop is configured such that the third heat pump working fluid flows into the first working fluid heat exchanger in liquid form, exchanges heat with the first heat pump working fluid, undergoes a phase change and becomes steam, is compressed by the second working fluid compressor, enters the first waste heat utilization device to heat the lean liquid at the bottom of the desorption tower, then enters the first coupling heat exchanger to exchange heat with the rich liquid that is split off, and then passes through the second throttling valve to be throttled and cooled to become liquid again, before flowing back into the first working fluid heat exchanger.

5. The carbon dioxide capture system according to claim 3, wherein, The second waste heat recovery heat pump includes a second waste heat recovery heat exchanger, a third working fluid compressor, and a third throttle valve, which are sequentially connected by pipelines to form a third working fluid loop for the circulation of the second heat pump working fluid. The second waste heat utilization device is connected in the pipeline between the third working fluid compressor and the third throttle valve. The third working fluid loop is configured such that the second heat pump working fluid flows into the second waste heat recovery heat exchanger in liquid form and undergoes a phase change to become steam after exchanging heat with one of the lean liquids in the split stream. After being compressed by the third working fluid compressor, it enters the second waste heat utilization device to heat the medium-lean liquid at the bottom of the desorption tower. Then, it passes through the third throttling valve to be throttled and cooled to become liquid again before flowing into the second waste heat recovery heat exchanger.

6. The carbon dioxide capture system according to claim 3, wherein, The third waste heat recovery heat pump is a two-stage compression heat pump, which includes a third heat pump unit and a fourth heat pump unit. The third heat pump unit includes a fourth waste heat recovery heat exchanger, a fourth working fluid compressor, a second working fluid heat exchanger, and a fourth throttle valve, which are sequentially connected by pipelines to form a fourth working fluid loop for the circulation of the fourth heat pump working fluid. The fourth heat pump unit includes a second working fluid heat exchanger, a fifth working fluid compressor, and a fifth throttle valve, which are sequentially connected by pipelines to form a fifth working fluid loop for the circulation of the fifth heat pump working fluid. The third waste heat utilization device and the second coupling heat exchanger are connected sequentially in the pipeline between the fifth working fluid compressor and the fifth throttling valve according to the flow direction of the fifth heat pump working fluid; The fourth working fluid loop is configured such that the fourth heat pump working fluid flows into the fourth waste heat recovery heat exchanger in liquid state to absorb the waste heat of the reaction and undergo a phase change to become steam. After being compressed by the fourth working fluid compressor, it enters the second working fluid heat exchanger to exchange heat with the liquid fifth heat pump working fluid. Then, it passes through the fourth throttling valve to be throttled and cooled to become liquid again, and then flows into the fourth waste heat recovery heat exchanger. The fifth working fluid loop is configured such that the fifth heat pump working fluid flows into the second working fluid heat exchanger in liquid state and undergoes a phase change to become steam after exchanging heat with the fourth heat pump working fluid. After being compressed by the fifth working fluid compressor, it enters the third waste heat utilization device to heat the lean liquid at the bottom of the desorption tower. Then, it enters the second coupling heat exchanger to exchange heat with the other rich liquid that is diverted. After that, it passes through the fifth throttling valve to be throttled and cooled to become liquid again, and then flows into the second working fluid heat exchanger.

7. The carbon dioxide capture system according to claim 1, wherein, The carbon dioxide capture system includes the first heat pump waste heat recovery and utilization component, but does not include the third heat pump waste heat recovery and utilization component. Furthermore, the carbon dioxide capture system also includes: The third waste heat recovery heat exchanger has its absorbent inlet and outlet connected to the absorbent outlet and absorbent return port of the absorption tower, respectively. Its working fluid inlet and outlet are connected in parallel with the working fluid inlet and outlet of the first waste heat recovery heat exchanger to the working fluid loop of the first waste heat recovery heat pump. This allows the working fluid of the first heat pump to be diverted into the first waste heat recovery heat exchanger and the third waste heat recovery heat exchanger, and the working fluids of the first heat pump flowing out of the first waste heat recovery heat exchanger and the third waste heat recovery heat exchanger to be combined and circulated. The third waste heat recovery heat exchanger is configured to allow the absorbent drawn from the absorption tower to exchange heat with the first heat pump working fluid entering it.

8. The carbon dioxide capture system according to any one of claims 1-7, further comprising: A gas-liquid separator is connected to the regeneration gas outlet of the desorption tower via a pipeline; A regenerated gas compression device is connected to the gas outlet of the gas-liquid separator; as well as The fifth waste heat recovery heat exchanger is connected to the second distributor, the regeneration gas compression device, and the fifth rich liquid inlet of the desorption tower, respectively. It is configured to allow the rich liquid diverted from the second distributor to exchange heat with the compressed regeneration gas generated by the regeneration gas compression device, and to output the rich liquid after heat exchange to the fifth rich liquid inlet.

9. The carbon dioxide capture system according to any one of claims 1-7, further comprising: A gas-liquid separator is connected to the regeneration gas outlet of the desorption tower via a pipeline; A regenerated gas compression device is connected to the gas outlet of the gas-liquid separator; as well as The fourth heat pump type waste heat recovery and utilization component includes: The fourth waste heat recovery heat pump includes a sixth waste heat recovery heat exchanger in a pipeline between the regenerated gas outlet of the desorption tower and the gas-liquid separator, and a seventh waste heat recovery heat exchanger connected to the regenerated gas compression device. The sixth waste heat recovery heat exchanger is configured to allow the sixth heat pump working fluid to exchange heat with the regenerated gas output from the regenerated gas outlet in the sixth waste heat recovery heat exchanger to recover the waste heat of the regenerated gas. The seventh waste heat recovery heat exchanger is configured to allow the sixth heat pump working fluid to exchange heat with the compressed regenerated gas generated by the regenerated gas compression device in the seventh waste heat recovery heat exchanger to recover the waste heat of the compressed regenerated gas. and The fourth waste heat utilization device is connected to the working fluid loop of the fourth waste heat recovery heat pump and is connected to the bottom of the desorption tower. It is configured to use the recovered waste heat of regenerated gas and the waste heat of compressed regenerated gas to heat the lean liquid at the bottom of the desorption tower through heat exchange for carbon dioxide desorption.

10. The carbon dioxide capture system according to claim 9, wherein, The heat pump working fluid flowing through the sixth waste heat recovery heat exchanger and the seventh waste heat recovery heat exchanger is the same sixth heat pump working fluid. The fourth waste heat recovery heat pump is a single-stage compression heat pump, which includes a seventh waste heat recovery heat exchanger, a sixth waste heat recovery heat exchanger, a sixth working fluid compressor, and a sixth throttle valve, which are sequentially connected by pipelines to form a sixth working fluid loop for the circulation of the working fluid of the sixth heat pump. The fourth waste heat utilization device is connected in the pipeline between the sixth working fluid compressor and the sixth throttle valve. The sixth working fluid loop is configured such that the sixth heat pump working fluid flowing out from the sixth throttling valve flows sequentially into the seventh waste heat recovery heat exchanger and the sixth waste heat recovery heat exchanger in a liquid state. After exchanging heat with the compressed regenerated gas and the regenerated gas respectively, the working fluid undergoes a phase change and turns into steam. After being compressed by the sixth working fluid compressor, the working fluid enters the sixth waste heat utilization device to heat the lean liquid at the bottom of the desorption tower. Then, it passes through the sixth throttling valve to be throttled and cooled to turn into a liquid state, thereby completing the working fluid cycle.

11. The carbon dioxide capture system according to claim 9, wherein, The heat pump working fluid flowing through the sixth waste heat recovery heat exchanger and the seventh waste heat recovery heat exchanger is the same sixth heat pump working fluid. The fourth waste heat recovery heat pump is a single-stage compression heat pump, including the seventh waste heat recovery heat exchanger, the sixth waste heat recovery heat exchanger, the sixth working fluid compressor, and the sixth throttle valve. The seventh waste heat recovery heat exchanger and the sixth waste heat recovery heat exchanger are connected in parallel and then connected sequentially to the sixth working fluid compressor and the sixth throttle valve through pipelines to form a sixth working fluid loop for the circulation of the working fluid of the sixth heat pump. The fourth waste heat utilization device is connected in the pipeline between the sixth working fluid compressor and the sixth throttle valve. The sixth working fluid loop is configured such that the sixth heat pump working fluid flowing out from the sixth throttling valve is diverted in liquid form into the seventh waste heat recovery heat exchanger and the sixth waste heat recovery heat exchanger, respectively, to exchange heat with the compressed regenerated gas and the regenerated gas, and then undergo a phase change to become steam. After being compressed by the sixth working fluid compressor, it enters the sixth waste heat utilization device to heat the lean liquid at the bottom of the desorption tower. Afterwards, it passes through the sixth throttling valve to be throttled and cooled to become liquid, thereby completing the working fluid cycle.

12. The carbon dioxide capture system according to claim 10 or 11, wherein, The fourth heat pump type waste heat recovery and utilization component also includes: The third coupling heat exchanger is connected to the working fluid loop of the fourth waste heat recovery heat pump and is located downstream of the fourth waste heat utilization device. It is also connected to the pipeline between the second distributor and the cold rich liquid inlet of the lean-rich liquid heat exchanger. It is configured to allow the working fluid output by the fourth waste heat utilization device to exchange heat with a rich liquid branched out by the second distributor, and to output the rich liquid after heat exchange to the cold rich liquid inlet of the lean-rich liquid heat exchanger.

13. The carbon dioxide capture system according to claim 9, wherein, The fourth waste heat recovery heat pump includes an independent regenerated gas waste heat recovery heat pump unit and a compressed regenerated gas waste heat recovery heat pump unit. The regenerated gas waste heat recovery heat pump unit includes the sixth waste heat recovery heat exchanger to recover regenerated gas waste heat, and the compressed regenerated gas waste heat recovery heat pump unit includes the seventh waste heat recovery heat exchanger to recover compressed regenerated gas waste heat. The fourth waste heat utilization device includes an independent regenerated gas waste heat utilization device and a compressed regenerated gas waste heat utilization device. The regenerated gas waste heat utilization device is connected to the working fluid loop of the regenerated gas waste heat recovery heat pump unit and is connected to the bottom of the desorption tower. It is configured to use the recovered regenerated gas waste heat to heat the lean liquid at the bottom of the desorption tower through heat exchange for carbon dioxide desorption. The compressed regenerated gas waste heat utilization device is connected to the working fluid loop of the compressed regenerated gas waste heat recovery heat pump unit and is connected to the bottom of the desorption tower. It is configured to use the recovered compressed regenerated gas waste heat to heat the lean liquid at the bottom of the desorption tower through heat exchange for carbon dioxide desorption.

14. The carbon dioxide capture system according to claim 13, wherein, The regenerated gas waste heat recovery heat pump unit is a single-stage compression heat pump, including a sixth waste heat recovery heat exchanger, a seventh working fluid compressor, and a seventh throttling valve, which are sequentially connected by pipelines to form a seventh working fluid loop for the circulation of the seventh heat pump working fluid. The regenerated gas waste heat utilization device is connected to the pipeline between the seventh working fluid compressor and the seventh throttling valve. The seventh working fluid loop is configured such that the seventh heat pump working fluid flows into the sixth waste heat recovery heat exchanger in liquid form, exchanges heat with the regenerated gas, undergoes a phase change and becomes steam, is compressed by the seventh working fluid compressor, enters the regenerated gas waste heat utilization device to heat the lean liquid at the bottom of the desorption tower, and then passes through the seventh throttling valve to be throttled and cooled to become liquid again before flowing into the sixth waste heat recovery heat exchanger.

15. The carbon dioxide capture system according to claim 13, wherein, The compressed regenerated gas waste heat recovery heat pump unit is a single-stage compression heat pump, including a seventh waste heat recovery heat exchanger, an eighth working fluid compressor, and an eighth throttle valve that are sequentially connected by pipelines to form an eighth working fluid loop for the circulation of the eighth heat pump working fluid. The compressed regenerated gas waste heat utilization device is connected to the pipeline between the eighth working fluid compressor and the eighth throttle valve. The eighth working fluid loop is configured such that the eighth heat pump working fluid flows into the seventh waste heat recovery heat exchanger in liquid form, exchanges heat with the compressed regeneration gas, undergoes a phase change and becomes steam, is compressed by the eighth working fluid compressor, enters the compressed regeneration gas waste heat utilization device to heat the lean liquid at the bottom of the desorption tower, and then passes through the eighth throttling valve to be throttled and cooled to become liquid again before flowing into the seventh waste heat recovery heat exchanger.

16. The carbon dioxide capture system according to claim 2 or 9, wherein, Each waste heat recovery device includes a first reboiler, which is configured to allow the lean liquid drawn from the bottom of the desorption tower to exchange heat with the working fluid that has absorbed heat in the corresponding waste heat recovery heat pump for carbon dioxide desorption, and then return to the bottom of the desorption tower, and allow at least part of the working fluid after heat exchange to undergo a phase change to become a liquid working fluid, and output the working fluid after heat exchange. or Each waste heat recovery device includes a second reboiler connected to the bottom of the desorption tower, a condenser heat exchanger in the working fluid loop connected to the corresponding waste heat recovery heat pump, and a flash evaporator connected between the second reboiler and the condenser heat exchanger. The condenser heat exchanger is configured to exchange heat between the water entering the condenser and the working fluid that has absorbed heat in the corresponding waste heat recovery heat pump to generate a high-temperature fluid, and to at least partially condense the heat-exchanged working fluid into a liquid working fluid, and to output the heat-exchanged working fluid. The flash evaporator is configured to flash-evaporate the high-temperature fluid from the condenser heat exchanger to generate water vapor and liquid water, and to output the water vapor and liquid water to the second reboiler and the condenser heat exchanger, respectively. The second reboiler is configured to exchange heat between the lean liquid drawn from the bottom of the desorption tower and the water vapor from the flash evaporator to desorb carbon dioxide, and then return to the bottom of the desorption tower, while the water vapor condenses into condensate and is output to the condenser heat exchanger.

17. The carbon dioxide capture system according to claim 1, wherein, The absorbent used in the carbon dioxide capture system is a CO2 composite absorbent, which contains, by mass, 8-25% cyclic organic amines, 10-35% sterically hindered amines, 0.1-2.0% metal complexing agents, and the balance being water.

18. The carbon dioxide capture system according to claim 17, wherein, The cyclic organic amine is one or a mixture of piperazine, N-hydroxyethylpiperazine, 1-(2-hydroxyethyl)-4-aminopiperidine, 4-hydroxy-1-methylpiperidine, 3-aminomethylpyridine, N-aminoethylpiperazine, and aniline; The sterically hindered amine is one or a mixture of 2-amino-2-methyl-1-propanol, isopropanolamine, sodium aminoisobutyrate, and 2-amino-2-ethyl-1,3-propanediol. The metal complexing agent is one of ethylenediaminetetraacetic acid, tartaric acid tetrahydrate, or a mixture thereof.

19. The carbon dioxide capture system according to claim 18, wherein, The CO2 compound absorbent further comprises, by weight: 0.1-1% antioxidant, 0.1-1% corrosion inhibitor, and 0.01-0.1% antifoaming agent; The antioxidant is one or more of sodium metavanadate, potassium bismuth citrate, and sodium antimony gluconate; The corrosion inhibitor is one or a mixture of sodium molybdate, sodium tungstate, thiourea, sodium vanadate, potassium orthophosphate, sodium borate, and diethanolglycine. The antifoaming agent is one of dimethyl silicone oil, polypropylene glycol, or a mixture thereof.

20. The carbon dioxide capture system according to claim 1, wherein, The absorbent used in the carbon dioxide capture system is a CO2 composite absorbent, which contains, by mass, 10-25% cyclic organic amine, 10-35% sterically hindered amine, 3-12% soluble metal salt and the balance being water. The cyclic organic amine is one or a mixture of piperazine, N-hydroxyethylpiperazine, 1-(2-hydroxyethyl)-4-aminopiperidine, 4-hydroxy-1-methylpiperidine, 3-aminomethylpyridine, and N-aminoethylpiperazine. The sterically hindered amine is one or a mixture of 2-amino-2-methyl-1-propanol, isopropanolamine, sodium aminoisobutyrate, and 2-amino-2-ethyl-1,3-propanediol. The soluble metal salt is one or more of zinc sulfate, nickel sulfate, copper sulfate, cobalt sulfate, and manganese sulfate, or a mixture thereof.

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