Solvent absorption method carbon capture system and method

Abstract

The invention discloses a solvent absorption method carbon capture system and method.The solvent absorption method carbon capture system comprises an absorption tower, a desorption tower, a first heat exchanger and a flash evaporation device, and the absorption tower is provided with a first inlet and a first outlet; the desorption tower is provided with a second inlet and a second outlet; a hot-side inlet of the first heat exchanger is connected with the second outlet, a hot-side outlet is connected with the first inlet, a cold-side inlet of the first heat exchanger is connected with the first outlet, and a cold-side outlet is connected with the second inlet; the flash evaporation device is provided with a third inlet, a gas phase outlet and a liquid phase outlet, the third inlet is connected with the second outlet, the gas phase outlet is connected with the inner cavity of the desorption tower, and the liquid phase outlet is connected with the first inlet. The energy consumption and the cost can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas separation, and in particular relates to a solvent absorption carbon capture system and method. Background Art

[0002] A large amount of industrial flue gas emitted by coal-fired power plants contains 5% to 30% carbon dioxide. The emission of greenhouse gases has a great impact on the change of climate and environment.

[0003] In the related art, chemical absorption is used to capture and separate carbon dioxide, and the equipment used includes an absorption tower and a desorption tower. However, the reaction temperature of the solvent in the absorption tower to capture and absorb carbon dioxide is relatively low, and the solvent that absorbs carbon dioxide needs to consume a large amount of heat to desorb carbon dioxide in the desorption tower, resulting in high energy consumption and cost of the carbon capture system. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, an embodiment of the present invention proposes a solvent absorption carbon capture system that can reduce energy consumption and cost.

[0006] The embodiments of the present invention further provide a solvent absorption carbon capture method.

[0007] The solvent absorption carbon capture system of the embodiment of the present invention comprises:

[0008] an absorption tower having a first inlet and a first outlet;

[0009] a desorber having a second inlet and a second outlet;

[0010] a first heat exchanger, wherein a hot side inlet of the first heat exchanger is connected to the second outlet, and a hot side outlet is connected to the first inlet, and a cold side inlet of the first heat exchanger is connected to the first outlet, and a cold side outlet is connected to the second inlet;

[0011] A flash evaporation device, wherein the flash evaporation device has a third inlet, a gas phase outlet and a liquid phase outlet, the third inlet is connected to the second outlet, the gas phase outlet is connected to the inner cavity of the desorption tower, and the liquid phase outlet is connected to the first inlet;

[0012] Part of the light phase solution discharged from the second outlet of the desorption tower exchanges heat with the heavy phase solution discharged from the first outlet of the absorption tower in the first heat exchanger, and the remaining light phase solution discharged from the second outlet of the desorption tower is transported to the flash evaporation device, and the gas phase flashed by the flash evaporation device is transported to the desorption tower, and the liquid phase remaining after flashing by the flash evaporation device is transported to the absorption tower.

[0013] Part of the light phase solution discharged from the desorption tower of the embodiment of the present invention is heat exchanged with the heavy phase solution discharged from the absorption tower to achieve heat recovery, and the remaining part of the light phase solution discharged from the desorption tower is flashed through a flash evaporation device to achieve heat recovery. At the same time, the remaining liquid phase after flash evaporation is directly transported to the absorption tower.

[0014] In some embodiments, a first cooler is further included, which is connected to the first inlet of the absorption tower, and the first cooler is used to cool the light phase solution discharged through the hot side outlet of the first heat exchanger and the liquid phase remaining after flash evaporation of the flash device to a first preset temperature.

[0015] In some embodiments, a first compressor is further included, the first compressor being disposed between the gas phase outlet of the flash evaporation device and the desorption tower, and the first compressor being used to compress the gas phase flashed out of the flash evaporation device;

[0016] And / or, the lower middle portion of the desorption tower has a fourth inlet, and the gas phase flashed out by the flash evaporation device enters the inner cavity of the desorption tower through the fourth inlet.

[0017] In some embodiments, the method further includes a first pump, a second pump and a third pump, wherein the first pump is disposed between the first outlet and the cold side inlet of the first heat exchanger, the second pump is disposed between the second outlet and the hot side inlet of the first heat exchanger, and the third pump is disposed between the second outlet and the first inlet.

[0018] In some embodiments, the flow rate of the light phase solution flowing into the flash device from the second outlet is less than or equal to 50% of the total flow rate of the light phase solution discharged from the second outlet.

[0019] In some embodiments, part of the heavy phase solution discharged from the first outlet flows into the cold side inlet of the first heat exchanger, and the remaining heavy phase solution discharged from the first outlet directly flows into the top of the desorption tower;

[0020] Or, it also includes a second heat exchanger, part of the heavy phase solution discharged from the first outlet flows into the cold side inlet of the first heat exchanger, and the remaining heavy phase solution discharged from the first outlet flows into the cold side inlet of the second heat exchanger, the cold side outlet of the second heat exchanger is connected to the top of the desorption tower, and the hot side inlet of the second heat exchanger is connected to the exhaust port at the top of the desorption tower.

[0021] In some embodiments, the flow rate of the heavy phase solution flowing into the first heat exchanger from the first outlet is greater than or equal to 50% of the total flow rate of the heavy phase solution discharged from the first outlet.

[0022] In some embodiments, the desorption tower has multiple second inlets, which are arranged in sequence along the height direction of the desorption tower, and the second inlet connected to the cold side outlet of the first heat exchanger is lower than other second inlets in the height direction.

[0023] In some embodiments, a flow control system is further included, wherein the flow control system is used to detect and adjust the flow in each pipeline of the solvent absorption carbon capture system.

[0024] The solvent absorption carbon capture method of the embodiment of the present invention uses the solvent absorption carbon capture system of any of the above embodiments to capture carbon, and the method includes:

[0025] A mixed gas containing carbon dioxide is transported into the absorption tower from the bottom of the absorption tower, and a solvent is transported into the absorption tower from the top of the absorption tower, and the solvent contacts the mixed gas to capture carbon dioxide in the mixed gas;

[0026] The solvent that has absorbed carbon dioxide is discharged from the first outlet at the bottom of the absorption tower and transported to the desorption tower, and at least part of the solvent discharged from the first outlet enters the desorption tower after being heated by the first heat exchanger;

[0027] The solvent transported into the desorption tower is heated to desorb carbon dioxide;

[0028] The solvent discharged from the second outlet of the desorption tower is divided into two parts, and the flow ratio of the two parts of the solvent is adjusted, one part of the solvent is transported to the flash evaporation device for flash evaporation, the gas phase after flash evaporation flows back into the desorption tower, the liquid phase remaining after flash evaporation is transported to the absorption tower, and the other part of the solvent is transported into the absorption tower after heat exchange and cooling in the first heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic structural diagram of a solvent absorption carbon capture system according to an embodiment of the present invention.

[0030] Figure 2 It is a schematic structural diagram of a solvent absorption carbon capture system according to another embodiment of the present invention.

[0031] Reference numerals:

[0032] 1. Absorption tower; 2. Desorption tower; 3. First heat exchanger; 4. Flash device; 5. First cooler; 6. First compressor; 7. First pump; 8. Second pump; 9. Third pump; 10. First inlet; 11. First outlet; 12. Second inlet; 13. Second outlet; 14. Third inlet; 15. Gas phase outlet; 16. Liquid phase outlet. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0034] like Figure 1 As shown, the solvent absorption carbon capture system of the embodiment of the present invention comprises an absorption tower 1, a desorption tower 2, a first heat exchanger 3 and a flash device 4. The absorption tower 1 has a first inlet 10 and a first outlet 11, and the desorption tower 2 has a second inlet 12 and a second outlet 13.

[0035] The hot side inlet of the first heat exchanger 3 is connected to the second outlet 13, and the hot side outlet is connected to the first inlet 10, the cold side inlet of the first heat exchanger 3 is connected to the first outlet 11, and the cold side outlet is connected to the second inlet 12; the flash device 4 has a third inlet 14, a gas phase outlet 15 and a liquid phase outlet 16, the third inlet 14 is connected to the second outlet 13, the gas phase outlet 15 is connected to the inner cavity of the desorption tower 2, and the liquid phase outlet 16 is connected to the first inlet 10.

[0036] Part of the light phase solution discharged from the second outlet 13 of the desorption tower 2 exchanges heat with the heavy phase solution discharged from the first outlet 11 of the absorption tower 1 in the first heat exchanger 3, and the remaining light phase solution discharged from the second outlet 13 of the desorption tower 2 is transported to the flash evaporation device 4, and the gas phase flashed by the flash evaporation device 4 is transported to the desorption tower 2, and the liquid phase remaining after flashing by the flash evaporation device 4 is transported to the absorption tower 1, so as to ensure the temperature difference between the light phase solution and the heavy phase solution in the first heat exchanger 3, improve the heat exchange effect, and more efficiently recover and utilize the heat in the light phase solution.

[0037] It should be understood that the heavy phase solution is the solvent after carbon dioxide is absorbed, that is, the rich liquid; the light phase solution is the solvent after carbon dioxide is desorbed by heating, that is, the lean liquid; the temperature of the rich liquid discharged from the first outlet 11 is relatively low, and after heat exchange with the lean liquid discharged from the second outlet 13, the heated rich liquid enters the desorption tower 2 from the second inlet 12, and the cooled lean liquid enters the absorption tower 1 from the first inlet 10. Although the temperature of the lean liquid discharged from the second outlet 13 of the desorption tower 2 is higher than the temperature of the rich liquid discharged from the first outlet 11 of the absorption tower 1, part of the heat in the high-temperature lean liquid can be utilized in the indirect contact heat exchange.

[0038] In the embodiment of the present invention, part of the lean liquid discharged from the desorption tower 2 is heat exchanged with the rich liquid discharged from the absorption tower 1 to realize partial heat recovery. At the same time, the remaining lean liquid discharged from the desorption tower 2 is flashed through the flash evaporation device 4, and the flashed gas phase is transported into the desorption tower 2 to realize heat recovery. At the same time, the remaining liquid phase after the flash evaporation is directly transported to the absorption tower 1. The heat quality of the remaining liquid phase after the flash evaporation is low and is no longer recovered.

[0039] In some embodiments, the solvent absorption carbon capture system also includes a first cooler 5, which is connected to the first inlet 10 of the absorption tower 1. The first cooler 5 is used to cool the light phase solution discharged through the hot side outlet of the first heat exchanger 3 and the liquid phase remaining after flash evaporation in the flash evaporation device 4 to a first preset temperature.

[0040] Since the temperature at which the solvent in the absorption tower 1 absorbs carbon dioxide is relatively low, the embodiment of the present invention provides a first cooler 5 to cool the lean liquid entering the absorption tower 1 from the first inlet 10, thereby ensuring that the temperature of the lean liquid entering the absorption tower 1 is lower than the first preset temperature, thereby improving the carbon capture effect.

[0041] Specifically, the first preset temperature may be 30 degrees Celsius to 45 degrees Celsius.

[0042] The low-temperature medium in the first cooler 5 may be condensed water in the plant area, and the condensed water and the lean liquid are in indirect contact with each other in the first cooler 5 for heat exchange.

[0043] Optionally, the liquid phase outlet 16 of the flash device 4 and the hot side outlet of the first heat exchanger 3 are respectively provided with a first cooler 5 , and the lean liquids in different pipelines are cooled by different first coolers 5 .

[0044] Alternatively, the liquid phase outlet 16 of the flash device 4 and the hot side outlet of the first heat exchanger 3 share the same first cooler 5 .

[0045] In some embodiments, the solvent absorption carbon capture system further includes a first compressor 6 , which is disposed between the gas phase outlet 15 of the flash device 4 and the desorption tower 2 , and is used to compress the gas phase flashed out by the flash device 4 .

[0046] The high-temperature lean liquid transported to the flash device 4 is discharged during the low-pressure flash evaporation process. The gas phase is compressed and then transported to the desorption tower 2. Although the first compressor 6 has a certain energy consumption, compared with the recovered heat, it can achieve the purpose of heat recycling and energy saving as a whole.

[0047] Optionally, the flash device 4 and the first compressor 6 can be one group or multiple groups. The model and quantity of the flash device 4 can be reasonably selected according to the processing capacity of the solvent absorption carbon capture system and the flow ratio allocated to the flash device 4.

[0048] In some embodiments, the middle and lower part of the desorption tower 2 has a fourth inlet, and the gas phase flashed out by the flash evaporation device 4 enters the inner cavity of the desorption tower 2 through the fourth inlet.

[0049] It should be understood that the solvent at the bottom of the desorption tower 2 is heated and reboiled in a reboiler to achieve desorption, and the compressed gas phase is transported into the middle and lower part of the desorption tower 2, which can increase the heat in the middle and lower part of the desorption tower 2 and prevent heat from flowing out of the desorption tower 2 with the desorbed carbon dioxide, thereby reducing the energy consumed by the reboiler. At the same time, the low-temperature rich liquid entering from the top of the desorption tower 2 can be gradually heated and heated during the descending process, thereby reducing the energy consumption and desorption cost of the desorption tower 2.

[0050] In some embodiments, the solvent absorption carbon capture system further includes a first pump 7, a second pump 8 and a third pump 9, wherein the first pump 7 is disposed between the first outlet 11 and the cold side inlet of the first heat exchanger 3, the second pump 8 is disposed between the second outlet 13 and the hot side inlet of the first heat exchanger 3, and the third pump 9 is disposed between the second outlet 13 and the first inlet 10.

[0051] The embodiment of the present invention arranges a pump on the corresponding pipeline, so as to pressurize and transport the solvent in the pipeline, thereby ensuring the normal and stable circulation flow of the entire system.

[0052] In some embodiments, the flow rate of the light phase solution flowing into the flash device 4 from the second outlet 13 is less than or equal to 50% of the total flow rate of the light phase solution discharged from the second outlet 13 .

[0053] That is, the flow rate of the lean liquid flowing into the flash device 4 from the second outlet 13 is 50%, 45%, 43%, 38%, 33.6%, 28%, 20%, 19% or 15% of the total flow rate of the lean liquid discharged from the second outlet 13. When the flow rate of the lean liquid flowing into the flash device 4 from the second outlet 13 is too large, it is easy to cause the load of the flash device 4 to be too large, the equipment investment is too large, and the heat exchange and temperature increase requirement of the rich liquid in the first heat exchanger 3 cannot be met.

[0054] like Figure 2 As shown, in some embodiments, part of the heavy phase solution discharged from the first outlet 11 flows into the cold side inlet of the first heat exchanger 3 , and the remaining heavy phase solution discharged from the first outlet 11 directly flows into the top of the desorption tower 2 .

[0055] It should be noted that, after the flash evaporation device 4 is arranged, when the flow rate entering the flash evaporation device 4 is within a certain range, it can be ensured that the flash evaporation device 4 has a relatively high heat recovery efficiency. A part of the high-temperature lean liquid in the embodiment of the present invention is used to ensure the operating conditions of the flash evaporation device 4, and the other part of the high-temperature lean liquid is used to ensure the heat exchange and heating requirements of the rich liquid in the first heat exchanger 3. When there is still residual low-temperature rich liquid discharged from the first outlet 11 of the absorption tower 1, this part of the low-temperature rich liquid can be directly transported to the top of the desorption tower 2.

[0056] Furthermore, the solvent absorption carbon capture system also includes a second heat exchanger, part of the heavy phase solution discharged from the first outlet 11 flows into the cold side inlet of the first heat exchanger 3, and the remaining heavy phase solution discharged from the first outlet 11 flows into the cold side inlet of the second heat exchanger, the cold side outlet of the second heat exchanger is connected to the top of the desorption tower 2, and the hot side inlet of the second heat exchanger is connected to the exhaust port at the top of the desorption tower 2.

[0057] The carbon dioxide desorbed from the desorption tower 2 carries a large amount of heat, which is of relatively low quality and is often directly discharged. In the embodiment of the present invention, a second heat exchanger is provided to directly or indirectly contact and heat exchange a portion of the low-temperature rich liquid discharged from the first outlet 11 of the absorption tower 1 with the carbon dioxide gas discharged from the desorption tower 2, thereby further recovering the heat in the gas, recycling the low-quality heat, improving the heat recycling efficiency, and further reducing energy consumption.

[0058] Furthermore, the flow rate of the heavy phase solution flowing into the first heat exchanger 3 from the first outlet 11 is greater than or equal to 50% of the total flow rate of the heavy phase solution discharged from the first outlet 11 .

[0059] That is, the flow rate of the heavy phase solution flowing into the first heat exchanger 3 from the first outlet 11 is 50%, 55%, 63%, 68%, 73.6%, 78%, 80%, 89% or 95% of the total flow rate of the heavy phase solution discharged from the first outlet 11. When the flow rate of the rich liquid flowing into the first heat exchanger 3 from the first outlet 11 is too small, it will cause excessive heat loss and fail to fully absorb the heat in the high-temperature lean liquid.

[0060] The embodiment of the present invention reasonably distributes the flow of high-temperature lean liquid and low-temperature rich liquid, can better recycle heat through various statistics, improve the recycling efficiency of high-quality heat and low-quality heat, while taking into account the equipment investment cost and energy consumption saving, and improving practicality.

[0061] Optionally, the desorption tower 2 has multiple second inlets 12, which are arranged in sequence along the height direction of the desorption tower 2, and the second inlet 12 connected to the cold side outlet of the first heat exchanger 3 is lower than the other second inlets 12 in the height direction.

[0062] It should be understood that there are multiple second inlets 12 in the embodiment of the present invention, and the multiple second inlets 12 are arranged at intervals in the vertical direction. The temperature of the rich liquid entering the desorption tower 2 from the second inlets 12 at different heights is different, and the temperature gradually increases from top to bottom, so that the temperature of the low-temperature rich liquid gradually increases during the falling process, so that the flow directions of the rich liquid and the carbon dioxide gas are opposite, the heat exchange between the carbon dioxide gas and the rich liquid is more complete, and the energy consumption of the desorption tower 2 is reduced.

[0063] In some embodiments, the solvent absorption carbon capture system further includes a flow control system, which is used to detect and adjust the flow in each pipeline in the solvent absorption carbon capture system.

[0064] The flow control system includes a control console, a flow regulating valve, a flow sensor and other components, which are used to monitor the flow in the pipeline and control the flow in different pipelines according to the heat recovery strategy formulated by the solvent absorption carbon capture system.

[0065] The solvent absorption carbon capture method of the embodiment of the present invention uses the solvent absorption carbon capture system of any of the above embodiments to capture carbon, and the method includes:

[0066] S101. A mixed gas containing carbon dioxide is transported into the absorption tower from the bottom of the absorption tower, and a solvent is transported into the absorption tower from the top of the absorption tower. The solvent contacts the mixed gas to capture carbon dioxide in the mixed gas.

[0067] S102, the solvent (rich liquid) that has absorbed carbon dioxide is discharged from the first outlet at the bottom of the absorption tower and transported to the desorption tower, and at least part of the solvent discharged from the first outlet enters the desorption tower after being heated by the first heat exchanger.

[0068] S103, the solvent transported into the desorption tower is heated to desorb carbon dioxide.

[0069] S104. The solvent (lean liquid) discharged from the second outlet of the desorption tower is divided into two parts, and the flow ratio of the two parts of the solvent is adjusted, one part of the solvent is transported to the flash evaporation device for flash evaporation, the gas phase after flash evaporation flows back into the desorption tower, the liquid phase remaining after flash evaporation is transported to the absorption tower, and the other part of the solvent is transported to the absorption tower after heat exchange and cooling in the first heat exchanger.

[0070] The embodiment of the present invention not only divides the lean liquid into two parts, and recovers heat through heat exchange and flash evaporation respectively, but also divides the rich liquid into two parts, and recovers heat through heat exchange with the lean liquid and heat exchange with carbon dioxide gas respectively, thereby reducing the energy consumption and cost of the entire system, contributing to the efficient use of heat, and facilitating the promotion and application of carbon capture systems.

[0071] The following is described in conjunction with specific embodiments:

[0072] Example 1: A stream of 12% CO2, 77% N2, 6% O2 and 5% H2O at a flow rate of 13500 Nm3 / h is contacted with 30% 2-amino-2-methylpropanol (AMP) and 10% piperazine at a flow rate of 50 m3 / h and a solvent with a CO2 load of 0.15 in an absorber, and the CO2 absorption rate is 90%. In a process having an absorber, a desorber, a lean-rich liquid heat exchanger and a reboiler, and a rich liquid split ratio of 19%, the capture amount is 3 tons of CO2 / h, and the energy consumption for heating in the reboiler is 3.24 GJ / ton of CO2.

[0073] On the basis of the above process, the embodiment of the present invention adds partial lean liquid flash evaporation technology. The system and method of the embodiment of the present invention are used, and the lean liquid with a lean liquid diversion ratio of 15% is used for lean liquid flash evaporation. The regeneration heat consumption is 3.04GJ / ton CO2. The power consumption of the compressor is 12kwh, which is converted into a heat consumption of 0.03GJ / ton CO2 at steam temperature. The overall energy consumption is 3.04+0.03=3.07GJ / ton CO2, which saves 5.2% energy compared with 3.24GJ / ton CO2 of the conventional process in the related art.

[0074] Embodiment 2:

[0075] Under the same conditions as in Example 1, the lean liquid with a lean liquid split ratio of 25% is used for lean liquid flash evaporation, and the regeneration heat consumption is 2.9 GJ / ton CO2. The power consumption of the compressor is 20 kwh, which is converted into a heat consumption of 0.06 GJ / ton CO2 at steam temperature. The overall energy consumption is 2.9+0.06=2.96 GJ / ton CO2, which is 8.6% energy-saving compared with 3.24 GJ / ton CO2 of the conventional process in the related art.

[0076] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0077] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0078] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0079] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0080] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0081] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A solvent absorption carbon capture system, characterized in that: include: an absorption tower having a first inlet and a first outlet; a desorber having a second inlet and a second outlet; a first heat exchanger, wherein a hot side inlet of the first heat exchanger is connected to the second outlet, and a hot side outlet is connected to the first inlet, and a cold side inlet of the first heat exchanger is connected to the first outlet, and a cold side outlet is connected to the second inlet; A flash evaporation device, wherein the flash evaporation device has a third inlet, a gas phase outlet and a liquid phase outlet, the third inlet is connected to the second outlet, the gas phase outlet is connected to the inner cavity of the desorption tower, and the liquid phase outlet is connected to the first inlet; Part of the light phase solution discharged from the second outlet of the desorption tower exchanges heat with the heavy phase solution discharged from the first outlet of the absorption tower in the first heat exchanger, and the remaining light phase solution discharged from the second outlet of the desorption tower is transported to the flash evaporation device, and the gas phase flashed by the flash evaporation device is transported to the desorption tower, and the liquid phase remaining after flashing by the flash evaporation device is transported to the absorption tower.

2. The solvent absorption carbon capture system according to claim 1, characterized in that: It also includes a first cooler, which is connected to the first inlet of the absorption tower and is used to cool the light phase solution discharged through the hot side outlet of the first heat exchanger and the liquid phase remaining after flash evaporation in the flash evaporation device to a first preset temperature.

3. The solvent absorption carbon capture system according to claim 1, characterized in that: It also includes a first compressor, which is arranged between the gas phase outlet of the flash evaporation device and the desorption tower, and is used to compress the gas phase flashed out by the flash evaporation device; And / or, the lower middle portion of the desorption tower has a fourth inlet, and the gas phase flashed out by the flash evaporation device enters the inner cavity of the desorption tower through the fourth inlet.

4. The solvent absorption carbon capture system according to claim 1, characterized in that: It also includes a first pump, a second pump and a third pump. The first pump is arranged between the first outlet and the cold side inlet of the first heat exchanger, the second pump is arranged between the second outlet and the hot side inlet of the first heat exchanger, and the third pump is arranged between the second outlet and the first inlet.

5. The solvent absorption carbon capture system according to claim 1, characterized in that: The flow rate of the light phase solution flowing into the flash device from the second outlet is less than or equal to 50% of the total flow rate of the light phase solution discharged from the second outlet.

6. The solvent absorption carbon capture system according to any one of claims 1 to 5, characterized in that: Part of the heavy phase solution discharged from the first outlet flows into the cold side inlet of the first heat exchanger, and the remaining heavy phase solution discharged from the first outlet directly flows into the top of the desorption tower; Or, it also includes a second heat exchanger, part of the heavy phase solution discharged from the first outlet flows into the cold side inlet of the first heat exchanger, and the remaining heavy phase solution discharged from the first outlet flows into the cold side inlet of the second heat exchanger, the cold side outlet of the second heat exchanger is connected to the top of the desorption tower, and the hot side inlet of the second heat exchanger is connected to the exhaust port at the top of the desorption tower.

7. The solvent absorption carbon capture system according to claim 6, characterized in that: The flow rate of the heavy phase solution flowing into the first heat exchanger from the first outlet is greater than or equal to 50% of the total flow rate of the heavy phase solution discharged from the first outlet.

8. The solvent absorption carbon capture system according to claim 6, characterized in that: The desorption tower has a plurality of second inlets, which are arranged in sequence along the height direction of the desorption tower. The second inlet connected to the cold side outlet of the first heat exchanger is lower than the other second inlets in the height direction.

9. The solvent absorption carbon capture system according to claim 6, characterized in that: The system also includes a flow control system, which is used to detect and adjust the flow in each pipeline of the solvent absorption carbon capture system.

10. A solvent absorption carbon capture method, characterized in that: Carbon capture is performed using a solvent absorption carbon capture system according to any one of claims 1 to 9, the method comprising: A mixed gas containing carbon dioxide is transported into the absorption tower from the bottom of the absorption tower, and a solvent is transported into the absorption tower from the top of the absorption tower, and the solvent contacts the mixed gas to capture carbon dioxide in the mixed gas; The solvent that has absorbed carbon dioxide is discharged from the first outlet at the bottom of the absorption tower and transported to the desorption tower, and at least part of the solvent discharged from the first outlet enters the desorption tower after being heated by the first heat exchanger; The solvent transported into the desorption tower is heated to desorb carbon dioxide; The solvent discharged from the second outlet of the desorption tower is divided into two parts, and the flow ratio of the two parts of the solvent is adjusted, one part of the solvent is transported to the flash evaporation device for flash evaporation, the gas phase after flash evaporation flows back into the desorption tower, the liquid phase remaining after flash evaporation is transported to the absorption tower, and the other part of the solvent is transported into the absorption tower after heat exchange and cooling in the first heat exchanger.

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