Self-supplied heat source heat pump coupling system and method for regenerating carbon capture amine solution

Abstract

This invention belongs to the field of carbon capture, utilization, and storage technology, and relates to a self-sufficient heat source heat pump coupling system and method for regenerating carbon-captured amine solutions. The self-sufficient heat source heat pump coupling system includes a carbon-captured amine solution circulation subsystem, a high-temperature heat pump circulation subsystem, and at least one mid-tower cooling circulation loop. By setting up a liquid collection device, cooling system, pumping and redistribution system in the mid-section of the absorber tower, the heated rich liquid is extracted outside the tower, cooled to the target temperature, and then reinjected, thereby improving the absorbent absorption efficiency, reducing amine solution loss, and decreasing the cooling load within the tower. For the low-grade waste heat generated during the reaction, high-temperature heat pump technology is used to transport it to the reboiler to reach the required heat source temperature. This invention constructs a closed system for internal energy recycling, enabling amine solution regeneration without an external fossil fuel heat source, thereby reducing operating costs and completely eliminating direct carbon emissions during the regeneration process.

Description

Technical Field

[0001] This invention relates to a self-sufficient heat source heat pump coupling system and method for regenerating carbon-captured amine solutions, belonging to the field of carbon capture, utilization and storage technology. Background Technology

[0002] In the field of carbon capture, utilization and storage (CCUS) of industrial sources such as coal-fired power plants, steel plants, and cement plants, amine liquid chemical absorption has become the most widely used carbon capture technology due to its high technological maturity and good absorption efficiency. However, this process consumes a great deal of energy in both the absorption reaction in the absorption tower and the amine regeneration in the desorption tower (or regeneration tower).

[0003] Inside the absorption tower, the reaction between CO2 and chemical absorbents such as amine liquid is a strongly exothermic process, causing the temperature inside the tower to rise rapidly along its height. This directly leads to two interrelated negative effects: First, since the absorption reaction itself is exothermic, the heat continuously released during the reaction process will reduce the capture efficiency of the absorbent for CO2; second, the continuous accumulation of reaction heat requires the system to provide more cooling for the absorption tower, resulting in an increase in the cooling load of the absorption tower and an increase in system energy consumption.

[0004] To address the temperature rise issue in absorption towers, existing technologies often employ external circulation coolers at the top or bottom of the tower. This involves drawing out a portion of the amine solution, cooling it, and then re-returning it to the tower to achieve cooling. However, this method is indirect cooling and cannot effectively and promptly remove localized hot spots forming in the middle of the tower, resulting in limited cooling effect and slow response. Another solution involves installing coil-type coolers on the tower wall, but this method suffers from small heat transfer area, low heat exchange efficiency, difficult equipment maintenance, and susceptibility to blockages and corrosion, making large-scale application in practical industrial scenarios difficult.

[0005] At the other end of the system, the rich liquor in the desorption tower needs to be heated to a high temperature of approximately 120°C to break the chemical bonds between the amine and CO2, releasing high-purity CO2 gas and regenerating the amine solution. Currently, this regeneration heat source is typically provided in one of the following ways: one is to extract low-pressure steam from the power plant's steam turbine and pass it into the reboiler attached to the desorption tower to heat the rich liquor. This method essentially converts high-quality electrical energy into low-quality heat energy, reducing the power plant's own power generation efficiency and incurring high energy costs.

[0006] Another method involves burning natural gas directly below the reboiler to provide a heat source. While this avoids impacting power plant operations, it generates new and direct carbon emissions, completely contradicting the original intention of carbon capture technology to reduce emissions. Furthermore, its operating costs are heavily dependent on natural gas market price fluctuations, making its economic viability unstable. Summary of the Invention

[0007] The purpose of this invention is to provide a self-sufficient heat source heat pump coupling system and method for regenerating carbon-captured amine solutions, which is used to recover the reaction heat of the absorption process in the absorption tower, thereby performing interstage cooling and providing heat to the reboiler in the desorption tower.

[0008] The technical solution provided by this invention is as follows: A self-sufficient heat source heat pump coupling system for regenerating carbon-captured amine solution, comprising a carbon-captured amine solution circulation subsystem and a high-temperature heat pump circulation subsystem:

[0009] The carbon capture amine liquid circulation subsystem includes an absorption tower, a desorption tower, and a lean and rich liquid heat exchanger.

[0010] The absorption tower is equipped with a main rich liquid outlet, a lean liquid inlet, and at least one cooling circulation loop in the middle section of the tower.

[0011] The desorption tower is equipped with a rich liquid inlet and a lean liquid outlet;

[0012] The main rich liquid outlet of the absorption tower is connected to the rich liquid inlet of the desorption tower via a pipeline through the rich-lean liquid heat exchanger; the lean liquid outlet of the desorption tower is connected to the lean liquid inlet of the absorption tower via a pipeline through the rich-lean liquid heat exchanger.

[0013] The high-temperature heat pump cycle subsystem includes a compressor, a reboiler, a throttle valve, and at least one heat exchanger that serves as an evaporator.

[0014] Each of the cooling circulation loops in the middle section of the tower includes a heat exchange outlet and a heat exchange inlet. The heat source side inlet of the heat exchanger is connected to the heat exchange outlet of the absorption tower through a pipeline, and the heat source side outlet of the heat exchanger is connected to the heat exchange inlet of the absorption tower through a pipeline, thus forming a cooling circulation loop that extracts heat from the inside of the absorption tower.

[0015] The refrigerant side of the heat exchanger is connected to the compressor, the reboiler and the throttle valve in sequence through refrigerant pipelines, forming a closed heat pump circulation loop;

[0016] The desorption tower is also provided with a semi-rich liquid outlet, which is connected to the heat source side inlet of the reboiler, and the heat source side outlet of the reboiler is connected back to the desorption tower.

[0017] The technical solution provided by this invention has the following advantages compared with the prior art:

[0018] 1. Achieved internal energy circulation and carbon emission reduction: This invention uses the reaction heat generated by the CO2 absorption reaction in the absorption tower as the low-temperature heat source of the high-temperature heat pump system, and then uses this heat to drive the amine liquid regeneration process in the desorption tower. This replaces or significantly reduces the dependence on external fossil energy heat sources such as steam or natural gas. It not only reduces the external energy input of the system, but also fundamentally eliminates the direct carbon emissions generated by burning fossil fuels in the regeneration process.

[0019] 2. High system integration: This invention couples the carbon capture amine liquid circulation with the high-temperature heat pump circulation, and uses the rich liquid of the amine liquid system itself as a heat source to realize the internal heat recycling of the system, without requiring or reducing the external energy input.

[0020] 3. Stable and reliable operation: By removing the heat of reaction from the middle section of the absorber, the operating temperature inside the absorber is effectively controlled, which helps maintain a high CO2 capture efficiency. Simultaneously, the high-temperature heat pump system provides a continuous and stable heat source for the reboiler, ensuring stable regeneration of the absorber and thus ensuring the smooth operation of the entire carbon capture system.

[0021] 4. Significant economic benefits: Although the system increases the investment in heat pump units, the operating cost of the system is significantly reduced due to the substantial reduction in the cost of purchasing external heat sources. From the perspective of total life cycle cost analysis, this technical solution has an economic advantage compared to the traditional method of relying on external heat sources.

[0022] Based on the above technical solution, the present invention can be further improved as follows.

[0023] Furthermore, the high-temperature heat pump cycle subsystem also includes a distributor and a mixer; the number of outlets of the distributor is adapted to the number of cooling cycle loops in the middle section of the tower, the inlet of the distributor is connected to the outlet of the throttling valve, and each outlet of the distributor is connected to the refrigerant-side inlet of the heat exchanger of each cooling cycle loop in the middle section of the tower; the number of inlets of the mixer is adapted to the number of cooling cycle loops in the middle section of the tower, and each inlet of the mixer is connected to the refrigerant-side outlet of the heat exchanger of each cooling cycle loop in the middle section of the tower, and the outlet of the mixer is connected to the suction port of the compressor.

[0024] The beneficial effect of adopting the above-mentioned further scheme is that, by setting up a distributor and a mixer, a single heat pump cycle can be adapted to multiple mid-section cooling circulation loops of the tower. The distributor can allocate the flow rate of low-temperature refrigerant according to the load requirements of each mid-section cooling circulation loop of the tower, so as to achieve precise extraction of heat sources in different temperature zones in the absorption tower. The mixer ensures that the working fluid flowing out from each evaporator can be stably combined and enter the compressor, thus ensuring the balance and stability of the system operation.

[0025] Furthermore, the carbon capture amine liquid circulation subsystem also includes a rich liquid circulation pump corresponding to the number of cooling circulation loops in the middle section of the tower; each of the rich liquid circulation pumps is connected between the heat exchange outlet of the corresponding cooling circulation loop in the middle section of the tower and the heat source side inlet of the corresponding heat exchanger.

[0026] The beneficial effect of adopting the above-mentioned further scheme is that an independent rich liquid circulation pump is set up for each mid-section cooling loop of the tower, which provides the necessary fluid transport power, ensuring that the rich liquid collected from a specific location in the absorption tower can be stably and controllably transported to the corresponding heat exchanger for cooling and smoothly returned to the absorption tower, forming a complete and actively adjustable mid-section cooling circulation loop of the tower.

[0027] Furthermore, the absorption tower is equipped with multiple liquid collection devices along its height. The number of cooling circulation loops in the middle section of the tower is matched with the number of liquid collection devices. The liquid collection devices are connected to each of the cooling circulation loops in the middle section of the tower to extract heat from the rich liquid at different heights in the absorption tower.

[0028] The beneficial effect of adopting the above-mentioned further scheme is that it enables the system to collect rich liquid from different reaction heights (i.e. different temperature ranges) in the absorption tower, realizes the cascade utilization of heat in the tower, can more effectively remove the heat of reaction, thereby maintaining a better reaction temperature throughout the entire height of the absorption tower and improving the CO2 capture efficiency.

[0029] Furthermore, the number of cooling circulation loops in the middle section of the tower is two, including a first cooling circulation loop and a second cooling circulation loop in the middle section of the tower. The first cooling circulation loop includes a first heat exchange outlet and a first heat exchange inlet, and the second cooling circulation loop includes a second heat exchange outlet and a second heat exchange inlet. The number of heat exchangers is two, including a first heat exchanger and a second heat exchanger. The heat source side inlets of the first heat exchanger and the second heat exchanger are respectively connected to the first heat exchange outlet and the second heat exchange outlet of the absorption tower, and the heat source side outlets of the first heat exchanger and the second heat exchanger are respectively connected back to the absorption tower through the first heat exchange inlet and the second heat exchange inlet of the absorption tower.

[0030] Furthermore, it also includes a first cooler for cooling the CO2 gas output from the top of the desorption tower.

[0031] The beneficial effect of adopting the above-mentioned further scheme is that by setting up a first cooler to cool the high-temperature CO2 gas output from the top of the desorption tower, the temperature of the CO2 gas can be reduced, which facilitates subsequent compression, transportation and storage. At the same time, the volume of the cooled CO2 gas is reduced, which helps to reduce storage space and transportation costs.

[0032] Furthermore, the reboiler is a condensing reboiler, and one of the tube side or shell side of the reboiler serves as the condenser of the high-temperature heat pump cycle subsystem. One side of the reboiler and the bottom of the desorption tower form an amine liquid circulation loop.

[0033] Furthermore, it also includes a rich liquid pump, which is connected to the pipeline between the main rich liquid outlet of the absorption tower and the lean and rich liquid heat exchanger.

[0034] The beneficial effect of adopting the above-mentioned further scheme is that the rich liquid pump provides the necessary power to transport the main rich liquid at the bottom of the absorption tower to the desorption tower, overcomes the resistance of pipelines and equipment such as rich and lean liquid heat exchangers, and ensures the continuous and stable operation of the entire amine liquid circulation.

[0035] Furthermore, it also includes a lean solution pump connected to the pipeline between the lean solution outlet of the desorption tower and the lean-rich solution heat exchanger.

[0036] The beneficial effect of adopting the above-mentioned further scheme is that the lean liquid pump provides the necessary power to transport the lean liquid regenerated by the desorption tower back to the top of the absorption tower, which is a key guarantee for completing the amine liquid circulation and realizing continuous collection.

[0037] Furthermore, it also includes a reboiler circulation pump, which is installed on the pipeline between the heat source side outlet of the reboiler and the desorption tower.

[0038] The beneficial effect of adopting the above-mentioned further scheme is that a reboiler circulation pump is set up to drive the amine liquid at the bottom of the desorption tower to flow through the reboiler for forced circulation, which enhances the heat transfer effect in the reboiler and ensures the uniformity and stability of amine liquid regeneration.

[0039] Furthermore, it also includes a second cooler, which is disposed on the pipeline between the lean and rich liquid heat exchanger and the lean liquid inlet of the absorption tower.

[0040] The beneficial effect of adopting the above-mentioned further scheme is that a second cooler is set up before the lean liquid returns to the absorption tower to cool the lean liquid to a low temperature state suitable for CO2 absorption, thereby providing the lean liquid with the optimal temperature conditions at the top of the absorption tower and ensuring the initial absorption efficiency at the top of the absorption tower.

[0041] A method for regenerating carbon-capturing amine solution, utilizing the aforementioned self-contained heat source heat pump coupling system for regenerating carbon-capturing amine solution, includes:

[0042] Carbon capture and amine regeneration steps: Inside the absorption tower, lean liquor is brought into countercurrent contact with flue gas to capture CO2, reacting to generate rich liquor and releasing heat of reaction; a portion of the rich liquor generated in the absorption tower is drawn out through at least one mid-section cooling circulation loop and cooled in a heat exchanger, transferring the heat of reaction to the working fluid of the high-temperature heat pump circulation subsystem; the rich liquor after the absorption reaction is completed is drawn out from the bottom of the absorption tower and sent to the top of the desorption tower via a lean-rich liquor heat exchanger; after preheating, in the desorption tower, the rich liquor is heated and regenerated using the heat energy released in the reboiler by the high-temperature heat pump circulation subsystem, releasing CO2 gas and reducing the amine liquor to lean liquor; the regenerated lean liquor is returned to the absorption tower for recycling after recovering heat via the lean-rich liquor heat exchanger.

[0043] High-temperature heat pump cycle steps: The working fluid absorbs the reaction heat from the rich liquid in the cooling cycle loop of the middle section of the tower in the heat exchanger and evaporates into gas; the compressor compresses the gaseous working fluid to a high-temperature and high-pressure state; the high-temperature and high-pressure working fluid condenses and releases heat in the reboiler, providing heat energy for the regeneration of amine liquid in the desorption tower; the throttling valve throttles and reduces the pressure of the condensed working fluid and sends it back to the heat exchanger to complete the cycle.

[0044] This invention achieves interstage cooling and pumping circulation by setting up a liquid collection-cooling-pumping-redistribution system in the middle section of the absorption tower. The rich liquid after heating is drawn out of the tower, cooled to the target temperature, and then reinjected, thereby improving the absorption efficiency of the absorbent and reducing the loss of amine liquid and the cooling load inside the tower. For the low-grade waste heat generated during the reaction, high-temperature heat pump technology is used to transport it to the reboiler to reach the required heat source temperature, completely replacing or significantly replacing traditional steam or gas heat sources, thereby significantly reducing the energy consumption, operating costs and indirect carbon emissions of amine liquid regeneration. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the self-sufficient heat source heat pump coupling system of the present invention.

[0047] In the diagram, 1. Absorption tower; 2. Desorption tower; 3. Fan; 4. Rich liquor pump; 5. Lean / rich liquor heat exchanger; 6. Second cooler; 7. Lean liquor pump; 8. Reboiler circulation pump; 9. Compressor; 10. Reboiler; 11. Throttling valve; 12. Flow divider; 13. Mixer; 14. First heat exchanger; 15. Second heat exchanger; 16. First rich liquor circulation pump; 17. Second rich liquor circulation pump; 18. First cooler; 19. First-stage liquid collection device; 20. Second-stage liquid collection device; 21. Third-stage liquid collection device. Detailed Implementation

[0048] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the objects described and do not imply any priority in order or any specific technical meaning. Furthermore, the concepts of "connection" and "linkage" mentioned in this application, unless otherwise specified, are considered to include both direct connection (linkage) and indirect connection (linkage).

[0049] When interpreting the description of this application, it should be clarified that terms such as "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," indicating directions or positional relationships, are based on the perspective and layout shown in the accompanying drawings. They are intended to facilitate explanation and simplify the description process, and are not absolute limitations on the actual location, construction method, or operating mode of the described device or element. Therefore, these terms should not be construed as restrictive interpretations of the content of this application.

[0050] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0051] like Figure 1As shown, a self-sufficient heat source heat pump coupling system for regenerating carbon-captured amine liquid includes a carbon-captured amine liquid circulation subsystem and a high-temperature heat pump circulation subsystem. The carbon-captured amine liquid circulation subsystem includes an absorption tower 1, a desorption tower 2, and a lean-rich liquid heat exchanger 5. The absorption tower 1 is used for the reaction process of lean liquid absorbing CO2 from flue gas to produce rich liquid. The absorption tower 1 is provided with a main rich liquid outlet, a lean liquid inlet, and at least one mid-section cooling circulation loop. The desorption tower 2 is equipped with a reboiler 10 for heating and regenerating the rich liquid to produce lean liquid and CO2 gas. The desorption tower 2 is provided with a rich liquid inlet and a lean liquid outlet. The lean-rich liquid heat exchanger 5 allows the rich liquid and the regenerated lean liquid to exchange heat and recover heat. The main rich liquid outlet of the absorption tower 1 is connected to the rich liquid inlet of the desorption tower 2 via a pipeline through the lean-rich liquid heat exchanger 5. The lean liquid outlet of the desorption tower 2 is connected to the main rich liquid outlet of the absorption tower 1 via a pipeline through the lean-rich liquid heat exchanger 5. The lean-rich liquid heat exchanger 5 is connected to the lean liquid inlet of the absorption tower 1; the high-temperature heat pump circulation subsystem includes a compressor 9, a reboiler 10, a throttling valve 11, and at least one heat exchanger serving as an evaporator; each cooling circulation loop in the middle section of the tower includes a heat exchange outlet and a heat exchange inlet, the heat source side inlet of the heat exchanger is connected to the heat exchange outlet of the absorption tower 1 via a pipeline, and the heat source side outlet of the heat exchanger is connected to the heat exchange inlet of the absorption tower 1 via a pipeline, forming a cooling circulation loop that extracts heat from inside the absorption tower 1; the refrigerant side of the heat exchanger is connected to the compressor 9, the reboiler 10, and the throttling valve 11 in sequence via refrigerant pipelines, forming a closed heat pump circulation loop; the desorption tower 2 is also provided with a semi-rich liquid outlet, the semi-rich liquid outlet is connected to the heat source side inlet of the reboiler 10, and the heat source side outlet of the reboiler 10 is connected back to the desorption tower 2.

[0052] The compressor 9 can be a centrifugal or screw compressor suitable for high-temperature working fluids. The reboiler 10 serves as the condenser of the high-temperature heat pump cycle subsystem. The high-temperature heat pump working fluid condenses and releases heat in the reboiler 10, transferring the heat to the amine liquid in the reboiler 10 and heating it to the regeneration temperature (≥120°C). The condensed high-pressure liquid working fluid is depressurized by the throttling valve 11. The heat source side of the reboiler 10 is connected to the high-temperature heat pump cycle system, ensuring that the heat of the reboiler 10 originates solely from the high-temperature heat pump cycle system. This invention does not include pipes or devices connected to an external steam or gas source for heating the reboiler 10. In operation, all the heat required for the reboiler 10 is provided by the high-temperature heat pump cycle subsystem.

[0053] The high-temperature heat pump cycle subsystem also includes a distributor 12 and a mixer 13. The distributor 12 adjusts the split ratio in a timely manner according to the load on the heat source side. After the working fluid recovers heat, it is mixed with the gas and then enters the compressor 9 to complete the cycle. More specifically, the number of outlets of the distributor 12 is adapted to the number of cooling loops in the middle section of the tower. The inlet of the distributor 12 is connected to the outlet of the throttle valve 11, and each outlet of the distributor 12 is connected to the refrigerant-side inlet of the heat exchanger of each cooling loop in the middle section of the tower. The number of inlets of the mixer 13 is adapted to the number of cooling loops in the middle section of the tower. Each inlet of the mixer 13 is connected to the refrigerant-side outlet of the heat exchanger of each cooling loop in the middle section of the tower, and the outlet of the mixer 13 is connected to the suction port of the compressor 9. By setting up the distributor 12 and the mixer 13, a single heat pump cycle can be adapted to multiple mid-section cooling circulation loops of the tower. The distributor 12 can allocate the flow rate of the low-temperature refrigerant according to the load requirements of each mid-section cooling circulation loop of the tower, so as to achieve precise extraction of heat sources in different temperature zones within the absorption tower 1. The mixer 13 ensures that the working fluid flowing out from each heat exchanger can be stably combined and then enter the compressor 9, thus ensuring the balance and stability of the system operation.

[0054] The carbon capture amine liquid circulation subsystem also includes rich liquid circulation pumps corresponding to the number of cooling circulation loops in the middle section of the tower. Each rich liquid circulation pump is connected between the heat exchange outlet of the corresponding cooling circulation loop in the middle section of the tower and the heat source side inlet of the corresponding heat exchanger. Providing an independent rich liquid circulation pump for each cooling circulation loop in the middle section of the tower provides the necessary fluid transport power, ensuring that the rich liquid collected from a specific location within the absorption tower 1 can be stably and controllably transported to the corresponding heat exchanger for cooling and smoothly returned to the absorption tower 1, forming a complete and actively adjustable cooling circulation loop in the middle section of the tower.

[0055] The absorption tower 1 is equipped with multiple stages of liquid collection devices along its height. The number of cooling circulation loops in the middle section of the tower is matched with the number of liquid collection devices. Each liquid collection device is connected to one of the cooling circulation loops in the middle section of the tower to extract heat from the rich liquid at different heights within the absorption tower 1. This allows the system to collect rich liquid from different reaction heights (i.e., different temperature ranges) within the absorption tower 1, achieving tiered utilization of heat within the tower. This enables more effective removal of reaction heat, thereby maintaining a more optimal reaction temperature throughout the entire height of the absorption tower 1 and improving CO2 capture efficiency.

[0056] In this embodiment, there are two cooling circulation loops in the middle section of the tower, including a first cooling circulation loop and a second cooling circulation loop in the middle section of the tower. There are two rich liquid circulation pumps, namely a first rich liquid circulation pump 16 and a second rich liquid circulation pump 17. The first cooling circulation loop in the middle section of the tower includes a first heat exchange outlet and a first heat exchange inlet, and the second cooling circulation loop in the middle section of the tower includes a second heat exchange outlet and a second heat exchange inlet. There are two heat exchangers, including a first heat exchanger 14 and a second heat exchanger 15. The heat source side inlets of the first heat exchanger 14 and the second heat exchanger 15 are respectively connected to the first heat exchange outlet and the second heat exchange outlet of the absorption tower 1. The heat source side outlets of the first heat exchanger 14 and the second heat exchanger 15 are respectively connected back to the absorption tower 1 through the first heat exchange inlet and the second heat exchange inlet of the absorption tower 1.

[0057] The system also includes a first cooler 18 for cooling the CO2 gas output from the top of the desorption tower 2. By setting the first cooler 18 to cool the high-temperature CO2 gas output from the top of the desorption tower 2, the temperature of the CO2 gas can be reduced, which facilitates subsequent compression, transportation and storage. At the same time, the volume of the cooled CO2 gas is reduced, which helps to reduce storage space and transportation costs.

[0058] The reboiler 10 is a condensing reboiler. One of the tube side or shell side of the reboiler 10 serves as the condenser of the high-temperature heat pump cycle subsystem. One side of the reboiler 10 and the bottom of the desorption tower 2 form an amine liquid circulation loop.

[0059] The system also includes a rich solution pump 4, which is connected to the pipeline between the main rich solution outlet of the absorption tower 1 and the lean-rich solution heat exchanger 5. The rich solution pump 4 is used to transport the rich solution from the absorption tower 1 to the desorption tower 2. The rich solution pump 4 provides power for transporting the main rich solution from the bottom of the absorption tower 1 to the desorption tower 2, overcoming the resistance of the pipeline and the lean-rich solution heat exchanger 5, and ensuring the continuous and stable operation of the entire amine solution cycle.

[0060] The system also includes a lean solution pump 7, which is connected to the pipeline between the lean solution outlet of the desorption tower 2 and the lean-rich solution heat exchanger 5. The lean solution pump 7 provides the necessary power to transport the lean solution regenerated from the desorption tower 2 back to the top of the absorption tower 1.

[0061] The system also includes a reboiler circulation pump 8, which is installed on the pipeline between the heat source side outlet of the reboiler 10 and the desorption tower 2. The reboiler circulation pump 8 is used to drive the amine solution at the bottom of the desorption tower 2 through the reboiler 10 for forced circulation, enhancing the heat transfer effect within the reboiler 10 and ensuring the uniformity and stability of the amine solution regeneration.

[0062] The system also includes a second cooler 6, which is installed on the pipeline between the lean and rich liquid heat exchanger 5 and the lean liquid inlet of the absorption tower 1. The second cooler 6 is installed before the lean liquid returns to the absorption tower 1 to cool it to a low temperature suitable for CO2 absorption, providing the top of the absorption tower 1 with lean liquid at the optimal temperature, thereby ensuring the initial absorption efficiency at the top of the absorption tower 1.

[0063] The operation of this system is accomplished by the coordinated operation of the carbon capture amine liquid regeneration cycle and the high-temperature heat pump cycle, including the carbon capture amine liquid regeneration cycle and the high-temperature heat pump cycle.

[0064] The working principle and specific operation method of this invention are illustrated below using the example of setting up two mid-section cooling circulation loops in the middle section of absorption tower 1:

[0065] The carbon capture and amine regeneration cycle steps are as follows: The pretreated coal-fired flue gas is sent to the bottom of the absorption tower 1 by the blower 3. The low-temperature lean liquid, cooled by the second cooler 6, enters from the top of the tower and comes into countercurrent contact with the flue gas through the distributor, absorbing CO2 in the flue gas and undergoing an exothermic reaction to generate rich liquid. The purified flue gas is discharged from the top of the absorption tower 1.

[0066] Inside the absorption tower 1, the heat of reaction between the amine solution and CO2 causes the temperature inside the tower to rise. Three stages of liquid collection devices are installed along the height of the absorption tower 1: a first-stage liquid collection device 19, a second-stage liquid collection device 20, and a third-stage liquid collection device 21. These devices are arranged sequentially from top to bottom within the absorption tower 1. The system removes the heat of reaction through two cooling circulation loops in the middle of the tower: the high-temperature rich liquid generated by the first-stage liquid collection device 19 is extracted by the first rich liquid circulation pump 16 and transported to the first heat exchanger 14 for cooling. The cooled, low-temperature rich liquid is then returned to the second-stage liquid collection device 20 to continue participating in the reaction. The high-temperature rich liquid generated by the second-stage liquid collection device 20 is extracted by the second rich liquid circulation pump 17 and transported to the second heat exchanger 15 for cooling. The cooled, low-temperature rich liquid is then returned to the third-stage liquid collection device 21 within the absorption tower 1. After the absorption reaction is completed, the main rich liquid drawn from the bottom of the absorption tower 1 is transported by the rich liquid pump 4, preheated by the lean and rich liquid heat exchanger 5, and then enters the top of the desorption tower 2.

[0067] Inside the desorption tower 2, the rich liquor is heated to approximately 120°C by the heat energy provided by the reboiler 10, and CO2 is desorbed, regenerating the rich liquor into a lean liquor. The desorbed high-temperature, high-purity CO2 gas is cooled and purified by the first cooler 18 and collected for subsequent use. The regenerated lean liquor is drawn from the bottom of the tower by the lean liquor pump 7, flows through the lean-rich liquor heat exchanger 5 to recover heat, and then is cooled to the absorption temperature by the second cooler 6 before finally being sent back to the top of the absorption tower 1, completing the amine liquor cycle.

[0068] The high-temperature heat pump cycle steps are as follows: The low-temperature, low-pressure heat pump working fluid is compressed to a high-temperature, high-pressure state in compressor 9. The high-temperature, high-pressure working fluid enters reboiler 10 (which serves as the condenser of the heat pump system), where it condenses and releases heat, transferring the heat to the amine liquid in desorption tower 2, providing all the heat energy for its regeneration. The condensed high-pressure working fluid is throttled by throttling valve 11, becoming a low-temperature, low-pressure gas-liquid two-phase state. Subsequently, the working fluid is divided into two streams by distributor 12. The two streams of working fluid enter the first heat exchanger 14 and the second heat exchanger 15 (which serve as the evaporators of the heat pump system), respectively, absorbing the reaction heat from the rich liquid in absorption tower 1 and evaporating. After absorbing heat, the two streams of working fluid are mixed in mixer 13 and then returned to the inlet of compressor 9, completing the entire heat pump cycle.

[0069] A method for regenerating carbon-capturing amine solution, utilizing the aforementioned self-contained heat source heat pump coupling system for regenerating carbon-capturing amine solution, includes:

[0070] Carbon capture and amine regeneration steps: Inside absorber 1, lean liquor is countercurrently contacted with flue gas to capture CO2, reacting to generate rich liquor and releasing heat of reaction; the rich liquor generated from the partial reaction inside absorber 1 is drawn out through at least one mid-section cooling circulation loop and cooled in a heat exchanger, transferring the heat of reaction to the working fluid of the high-temperature heat pump circulation subsystem; the rich liquor after the absorption reaction is completed is drawn out from the bottom of absorber 1 and sent to the top of desorption tower 2 via lean-rich liquor heat exchanger 5; after preheating, in desorption tower 2, the rich liquor is heated and regenerated using the heat energy released by the high-temperature heat pump circulation subsystem in reboiler 10, releasing CO2 gas and reducing the amine liquor to lean liquor; the regenerated lean liquor is sent back to absorber 1 for recycling after recovering heat via lean-rich liquor heat exchanger 5.

[0071] High-temperature heat pump cycle steps: The working fluid absorbs the reaction heat from the rich liquid in the cooling cycle loop of the middle section of the tower in the heat exchanger and evaporates into gas; the compressor 9 compresses the gaseous working fluid to a high-temperature and high-pressure state; the high-temperature and high-pressure working fluid condenses and releases heat in the reboiler 10 to provide heat energy for the regeneration of amine liquid in the desorption tower 2; the throttling valve 11 throttles and reduces the pressure of the condensed working fluid and sends it back to the heat exchanger to complete the cycle.

[0072] The carbon capture amine liquid regeneration method of the present invention constructs a closed system for internal energy recycling by using the heat of CO2 reaction in the absorption tower 1 as the sole heat source of the heat pump system and using it to drive the regeneration process of the desorption tower 2. This enables amine liquid regeneration to be completed without the need for an external fossil energy heat source, thereby reducing operating costs and completely eliminating direct carbon emissions in the regeneration process.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of amine solution regeneration for carbon capture, characterized by: A self-sufficient heat source heat pump coupling system for regenerating carbon-captured amine liquid is used. The system includes a carbon-captured amine liquid circulation subsystem and a high-temperature heat pump circulation subsystem. The carbon-captured amine liquid circulation subsystem includes an absorption tower (1), a desorption tower (2), and a lean and rich liquid heat exchanger (5). The absorption tower (1) is provided with a main rich liquid outlet, a lean liquid inlet, and at least one cooling circulation loop in the middle section of the tower; The desorption tower (2) is provided with a rich liquid inlet and a lean liquid outlet; The main rich liquid outlet of the absorption tower (1) is connected to the rich liquid inlet of the desorption tower (2) via a pipeline through the rich and lean liquid heat exchanger (5); the lean liquid outlet of the desorption tower (2) is connected to the lean liquid inlet of the absorption tower (1) via a pipeline through the rich and lean liquid heat exchanger (5). The high-temperature heat pump cycle subsystem includes a compressor (9), a reboiler (10), a throttle valve (11), and at least one heat exchanger; Each of the cooling circulation loops in the middle section of the tower includes a heat exchange outlet and a heat exchange inlet. The heat source side inlet of the heat exchanger is connected to the heat exchange outlet of the absorption tower (1) through a pipeline, and the heat source side outlet of the heat exchanger is connected to the heat exchange inlet of the absorption tower (1) through a pipeline, thus forming a cooling circulation loop that takes heat from the inside of the absorption tower (1). The refrigerant side of the heat exchanger is connected to the compressor (9), the reboiler (10) and the throttle valve (11) in sequence through refrigerant pipelines, forming a closed heat pump circulation loop; The desorption tower (2) is also provided with a semi-rich liquid outlet, which is connected to the heat source side inlet of the reboiler (10), and the heat source side outlet of the reboiler (10) is connected back to the desorption tower (2). The heat of the reboiler (10) comes solely from the high-temperature heat pump cycle subsystem. The self-sufficient heat source heat pump coupling system for carbon capture amine liquid regeneration does not include any pipes or devices connected to an external steam source or gas source for heating the reboiler (10). The methods include: Carbon capture and amine regeneration steps: In the absorption tower (1), the lean liquid is brought into countercurrent contact with the flue gas to capture CO2, react to generate rich liquid and release reaction heat; the rich liquid generated in the absorption tower (1) is led out through at least one mid-section cooling circulation loop and cooled in a heat exchanger to transfer the reaction heat to the working fluid of the high-temperature heat pump circulation subsystem; the absorption tower (1) is equipped with three-stage liquid collection devices along the height of the tower, namely the first-stage liquid collection device (19), the second-stage liquid collection device (20) and the third-stage liquid collection device (21), which are arranged from top to bottom in the absorption tower (1). The system removes the reaction heat through two mid-section cooling circulation loops: the high-temperature rich liquid generated by the first-stage liquid collection device (19) is pumped by the first rich liquid circulation pump (1) 6) The liquid is extracted and transported to the first heat exchanger (14) for cooling. The cooled low-temperature rich liquid is returned to the second-stage collection device (20) to continue participating in the reaction. The high-temperature rich liquid generated by the second-stage collection device (20) is extracted by the second rich liquid circulation pump (17) and transported to the second heat exchanger (15) for cooling. The cooled low-temperature rich liquid is returned to the third-stage collection device (21) in the absorption tower (1). The rich liquid after the absorption reaction is completed is drawn from the bottom of the absorption tower (1) and sent to the top of the desorption tower (2) through the lean and rich liquid heat exchanger (5). After preheating, the rich liquid is heated and regenerated in the desorption tower (2) by the heat energy released by the high-temperature heat pump circulation subsystem in the reboiler (10), releasing CO2 gas and reducing the amine liquid to lean liquid. The regenerated lean liquid is transported through the lean and rich liquid heat exchanger (5) to recover heat and then sent back to the absorption tower (1) for recycling. High-temperature heat pump cycle steps: The working fluid absorbs the reaction heat from the rich liquid in the cooling cycle loop of the middle section of the tower in the heat exchanger and evaporates into gas; the compressor (9) compresses the gas working fluid to a high-temperature and high-pressure state; the high-temperature and high-pressure working fluid condenses and releases heat in the reboiler (10) to provide heat energy for the regeneration of amine liquid in the desorption tower (2); the throttling valve (11) throttles and reduces the pressure of the condensed working fluid, and then the working fluid is divided into two paths through the splitter (12), and the two working fluids enter the first heat exchanger (14) and the second heat exchanger (15) respectively, absorb the reaction heat from the rich liquid in the absorption tower (1) and evaporate, and the two working fluids after absorbing heat are mixed in the mixer (13) and then returned to the inlet of the compressor (9) to complete the cycle.

2. The carbon capture amine liquid regeneration process of claim 1, characterized by: The high-temperature heat pump circulation subsystem also includes a distributor (12) and a mixer (13); the number of outlets of the distributor (12) is adapted to the number of cooling circulation loops in the middle section of the tower, the inlet of the distributor (12) is connected to the outlet of the throttle valve (11), and each outlet of the distributor (12) is connected to the refrigerant side inlet of the heat exchanger of each cooling circulation loop in the middle section of the tower; the number of inlets of the mixer (13) is adapted to the number of cooling circulation loops in the middle section of the tower, each inlet of the mixer (13) is connected to the refrigerant side outlet of the heat exchanger of each cooling circulation loop in the middle section of the tower, and the outlet of the mixer (13) is connected to the suction port of the compressor (9).

3. The carbon-capturing amine solution regeneration method according to claim 2, characterized in that: The carbon capture amine liquid circulation subsystem also includes a rich liquid circulation pump corresponding to the number of cooling circulation loops in the middle section of the tower; each of the rich liquid circulation pumps is connected between the heat exchange outlet of the corresponding cooling circulation loop in the middle section of the tower and the heat source side inlet of the corresponding heat exchanger.

4. The carbon-capturing amine solution regeneration method according to claim 1, characterized in that: It also includes a first cooler (18) for cooling CO2 gas output from the top of the desorption tower (2).

5. The carbon-capturing amine solution regeneration method according to claim 4, characterized in that: The reboiler (10) is a condensing reboiler. One of the tube side or shell side of the reboiler (10) serves as the condenser of the high-temperature heat pump cycle subsystem. One side of the reboiler (10) and the bottom of the desorption tower (2) form an amine liquid circulation loop.

6. The carbon-capturing amine solution regeneration method according to claim 1, characterized in that: It also includes a rich liquid pump (4), which is connected to the pipeline between the main rich liquid outlet of the absorption tower (1) and the lean and rich liquid heat exchanger (5).

7. The carbon-capturing amine solution regeneration method according to claim 6, characterized in that: It also includes a lean liquid pump (7), which is connected to the pipeline between the lean liquid outlet of the desorption tower (2) and the lean-rich liquid heat exchanger (5).

8. The carbon-capturing amine solution regeneration method according to claim 7, characterized in that: It also includes a reboiler circulation pump (8), which is installed on the pipeline between the heat source side outlet of the reboiler (10) and the desorption tower (2).

9. The carbon-capturing amine solution regeneration method according to claim 8, characterized in that: It also includes a second cooler (6), which is located on the pipeline between the lean and rich liquid heat exchanger (5) and the lean liquid inlet of the absorption tower (1).

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