Heat integration optimization carbon dioxide capture system

Abstract

The embodiment of the invention provides a heat integration optimization carbon dioxide capture system, which comprises an absorption tower, a gas inlet, a barren liquor inlet and a rich liquor outlet, the desorption tower is provided with a rich solution inlet, a barren solution outlet and a regenerated gas outlet which is formed in the top of the desorption tower and is communicated with the regenerated gas flue; the barren liquor pump is arranged on a barren liquor pipeline between the barren liquor inlet and the barren liquor outlet; the rich liquid pump is arranged on a rich liquid pipeline between the rich liquid outlet and the rich liquid inlet; the reboiler is arranged on the desorption tower and is used for desorbing the rich solution in the desorption tower; the input end of the main heat pump is connected with the industrial waste heat, and the output end of the main heat pump communicates with the reboiler and provides a heat source; the input end of the auxiliary heat pump is communicated with the regenerated gas outlet, and the output end of the auxiliary heat pump is communicated with the input end of the main heat pump; wherein the trapping system is configured to recover waste heat in regenerated gas in the desorption tower through the auxiliary heat pump, and the main heat pump adopts industrial waste heat to increase the temperature in the desorption tower step by step.

Description

Technical Field

[0001] Embodiments of the present disclosure belong to the technical field of carbon capture equipment, and particularly relate to a heat-integrated optimized carbon dioxide capture system. Background Art

[0002] In the traditional amine-based carbon capture process, after CO2 is absorbed, the solvent needs to be heated (usually using steam) to release CO2 and regenerate the solvent. However, the energy consumption of this regeneration process is relatively high, accounting for about 60–70% of the entire carbon capture cost.

[0003] The conventional steam regeneration method requires a high temperature above 100–120°C and relies on boiler steam, resulting in high additional energy consumption and serious heat loss during the regeneration process. Moreover, for traditional carbon capture organic amine solvents, processes such as regeneration in the solvent system mainly rely on high-temperature steam, and the heat discharged from the regeneration tower is not fully utilized, leading to serious energy waste, high operating costs and energy consumption, and low overall emission reduction efficiency.

[0004] Therefore, how to solve the above problems has become an urgent technical problem for those skilled in the art. Summary of the Invention

[0005] Embodiments of the present disclosure aim to at least solve one of the technical problems existing in the prior art, and provide a heat-integrated optimized carbon dioxide capture system.

[0006] One aspect of the embodiments of the present disclosure provides a heat-integrated optimized carbon dioxide capture system, including: an absorption tower provided with a flue gas inlet, a lean liquid inlet, and a rich liquid outlet;

[0007] A desorption tower provided with a rich liquid inlet, a lean liquid outlet, and a re-generated gas outlet provided at the top of the desorption tower and communicated with the re-generated gas flue;

[0008] A lean liquid pump provided in the lean liquid pipeline between the lean liquid inlet and the lean liquid outlet;

[0009] A rich liquid pump provided in the rich liquid pipeline between the rich liquid outlet and the rich liquid inlet;

[0010] A reboiler provided in the desorption tower for the rich liquid in the desorption tower;

[0011] A main heat pump, the input end of the main heat pump is connected to industrial waste heat, and the output end of the main heat pump is communicated with the reboiler and provides a heat source;

[0012] An auxiliary heat pump, the input end of the auxiliary heat pump is communicated with the re-generated gas outlet, and the output end of the auxiliary heat pump is communicated with the input end of the main heat pump;

[0013] Among them, the capture system is configured to recover the waste heat in the regeneration gas in the desorption tower through the auxiliary heat pump, and the main heat pump uses the industrial waste heat to gradually increase the temperature in the desorption tower.

[0014] Further, it further includes: a heat exchanger, the heat exchanger is respectively connected to the lean liquid pipeline and the rich liquid pipeline, and the heat exchanger is used for heat exchange between the lean liquid and the rich liquid in the lean liquid pipeline and the rich liquid pipeline.

[0015] Further, it further includes: a cooler, the cooler is arranged on the lean liquid pipeline and downstream of the lean liquid pump.

[0016] Optionally, the auxiliary heat pump includes an auxiliary compressor communicated with the regeneration gas outlet, and an auxiliary condenser connected to the auxiliary compressor, and the auxiliary condenser is used to transfer the heat in the gas heated by the auxiliary compressor to the main heat pump.

[0017] Optionally, the main heat pump includes a main compressor communicated with the auxiliary heat pump, and a main condenser connected to the main compressor, and the main condenser is used to transfer the heat in the gas heated by the main compressor to the reboiler.

[0018] Further, it further includes: a first flow control valve, the first flow control valve is arranged on the pipeline between the input end of the auxiliary heat pump and the regeneration gas outlet.

[0019] Further, it further includes: a second flow control valve, the second flow control valve is arranged on the pipeline between the output end of the main heat pump and the reboiler.

[0020] Optionally, in the direction from the bottom to the top of the absorption tower, the rich liquid outlet, the flue gas inlet, and the lean liquid inlet are sequentially arranged at intervals.

[0021] Optionally, in the direction from the bottom to the top of the desorption tower, the lean liquid outlet, the rich liquid inlet, and the regeneration gas outlet are sequentially arranged at intervals.

[0022] Optionally, both the reboiler and the main heat pump are arranged at the bottom of the desorption tower,

[0023] Among them, the pipeline connecting the output end of the main heat pump is inserted into the desorption tower and communicated with the reboiler.

[0024] The beneficial effects of the embodiments of the present disclosure include:

[0025] In the present invention, the main heat pump recovers industrial waste heat (such as flue gas, cooling water), heats it to a preset temperature and then inputs it into the reboiler. The utilization of this industrial waste heat replaces part of the steam demand, thereby effectively reducing the dependence on boiler steam and saving high-quality heat energy.

[0026] The auxiliary heat pump captures the condensation heat in the regeneration gas at the top of the desorption tower, and after the temperature is raised, it preheats the rich liquid or returns it to the main heat pump, effectively improving the thermal energy utilization rate, further reducing the operating cost and energy consumption, and making full use of the heat discharged from the desorption tower. Description of the Drawings

[0027] Figure 1 It is a schematic structural diagram of a heat integration optimized carbon dioxide capture system according to an embodiment of the present disclosure.

[0028] In the figure, 1 is an absorption tower; 2 is a desorption tower; 3 is a lean liquid pump; 4 is a lean liquid pipeline; 5 is a rich liquid pump; 6 is a rich liquid pipeline; 7 is a reboiler; 8 is a main heat pump; 9 is an auxiliary heat pump; 10 is a heat exchanger; 11 is a cooler; 12 is a first flow control valve; 13 is a second flow control valve; 14 is a flue gas inlet. Detailed Embodiments

[0029] To enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure will be further described in detail below in conjunction with the drawings and specific embodiments.

[0030] The following further describes the embodiments of the present application in detail in conjunction with the drawings. The detailed description and drawings of the following embodiments are used to exemplarily illustrate the principle of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments. In the description of the present application, it should be noted that unless otherwise specified, the meaning of "a plurality" is two or more; the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate the orientation or positional relationship only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. "Vertical" is not strictly vertical, but within the allowable error range. "Parallel" is not strictly parallel, but within the allowable error range.

[0031] In the description of the present application, it should also be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0032] The heat integration optimized carbon dioxide capture system of the present invention is aimed at traditional organic amine solvents for carbon capture. In the solvent system, processes such as regeneration mainly rely on high-temperature steam. However, the heat discharged from the regeneration tower is not fully utilized, resulting in serious energy waste, high operating costs and energy consumption, and low overall emission reduction efficiency.

[0033] As Figure 1 shown, a heat integration optimized carbon dioxide capture system includes: an absorption tower 1, a desorption tower 2, a lean liquid pump 3, a rich liquid pump 5, a reboiler 7, a main heat pump 8, and an auxiliary heat pump 9. The absorption tower 1 is provided with a flue gas inlet 14, a lean liquid inlet, and a rich liquid outlet. The desorption tower 2 is provided with a rich liquid inlet, a lean liquid outlet, and a reboiler outlet disposed at the top of the desorption tower and communicating with the reboiler flue. The lean liquid pump 3 is disposed in a lean liquid pipeline 4 between the lean liquid inlet and the lean liquid outlet.

[0034] The rich liquid pump 5 is disposed in a rich liquid pipeline 6 between the rich liquid outlet and the rich liquid inlet. The reboiler 7 is disposed in the desorption tower 2 for the rich liquid in the desorption tower 2. The input end of the main heat pump 8 is connected to industrial waste heat, and the output end of the main heat pump 8 communicates with the reboiler 7 and provides a heat source. The input end of the auxiliary heat pump 9 communicates with the reboiler outlet of the desorption tower 2, and the output end of the auxiliary heat pump 9 communicates with the input end of the main heat pump 8.

[0035] Wherein, the capture system is configured to recover the waste heat in the reboiler gas in the desorption tower 2 through the auxiliary heat pump 9, and the main heat pump 8 uses the industrial waste heat to gradually increase the temperature in the desorption tower 2.

[0036] In the present invention, the main heat pump 8 recovers industrial waste heat (such as flue gas and cooling water), and after heating to a preset temperature, it is input into the reboiler 7. The utilization of this industrial waste heat replaces a part of the steam demand, thereby effectively reducing the dependence on boiler steam and saving high-quality heat energy.

[0037] The auxiliary heat pump 9 captures the condensation heat in the reboiler gas at the top of the desorption tower 2, and after heating, it preheats the rich liquid or returns it to the main heat pump 8, so that the heat energy utilization rate is effectively improved, the operating cost and energy consumption are further reduced, and the heat discharged from the desorption tower 2 is fully utilized.

[0038] In some embodiments, the system further includes a heat exchanger 10. The heat exchanger 10 is respectively connected to the lean liquid pipeline 4 and the rich liquid pipeline 6. The heat exchanger 10 is used for heat exchange between the lean liquid and the rich liquid in the lean liquid pipeline 4 and the rich liquid pipeline 6.

[0039] In the present invention, the waste heat of the rich liquid in the heat exchanger 10 is used to preheat the lean liquid, thereby reducing the heating load of the reboiler 7. The heating energy required for the preheated lean liquid is reduced, the overall energy consumption of the system is lowered, and the energy utilization efficiency is significantly improved. In addition, through heat exchange, the temperatures of the lean liquid and the rich liquid are closer to the ranges required by the process, which helps to maintain the stable operating conditions of the absorption tower 1 and the desorption tower 2.

[0040] In some embodiments, the system further includes a cooler 11, which is disposed in the lean liquid pipeline 4 and arranged downstream of the lean liquid pump 3.

[0041] In the present invention, by cooling the lean liquid through the cooler 11, the optimal absorption state of the lean liquid can be ensured. In addition, the cooler 11 reduces the temperature fluctuation of the lean liquid, ensures the stable operation of the absorption tower 1, and improves the overall controllability of the system.

[0042] In some embodiments, the auxiliary heat pump 9 includes an auxiliary compressor communicated with the outlet of the regenerated gas, and an auxiliary condenser connected to the auxiliary compressor. The auxiliary condenser is used to exchange the heat in the gas heated by the auxiliary compressor to the main heat pump 8.

[0043] In some embodiments, the main heat pump 8 includes a main compressor communicated with the auxiliary heat pump 9, and a main condenser connected to the main compressor. The main condenser is used to exchange the heat in the gas heated by the main compressor to the reboiler 7.

[0044] In some embodiments, the system further includes a first flow control valve 12, which is disposed in the pipeline between the input end of the auxiliary heat pump 9 and the outlet of the regenerated gas.

[0045] In the present invention, the first flow control valve 12 can precisely adjust the flow rate of the regenerated gas, ensure the operation of the auxiliary heat pump 9 under stable working conditions, and avoid system instability caused by flow rate fluctuations. By slowing down the flow rate change, the pipeline pressure fluctuation is reduced, the impact on equipment and pipelines is decreased, and the service life of the equipment is prolonged.

[0046] In some embodiments, the system further includes a second flow control valve 13, which is disposed in the pipeline between the output end of the main heat pump 8 and the reboiler 7.

[0047] In the present invention, the second flow control valve 13 can accurately adjust the flow rate of the heat medium flowing from the main heat pump 8 to the reboiler 7, ensure that the heat supply capacity matches the actual demand of the desorption tower 2, and avoid heat waste or insufficient heat supply. When the load of the desorption tower 2 changes due to the change of the raw gas flow rate or composition, the second flow control valve 13 can quickly adjust the flow rate of the heat medium to meet the heat demand under different working conditions.

[0048] In some embodiments, in the direction from the bottom to the top of the absorption tower 1, the rich liquid outlet, the flue gas inlet 14, and the lean liquid inlet are sequentially arranged at intervals.

[0049] In some embodiments, in the direction from the bottom to the top of the desorption tower 2, the lean liquid outlet, the rich liquid inlet, and the regeneration gas outlet are sequentially arranged at intervals.

[0050] In some embodiments, the reboiler 7 and the main heat pump 8 are both arranged at the bottom of the desorption tower 2. Among them, the pipeline connecting the output end of the main heat pump 8 is inserted into the desorption tower 2 and communicated with the reboiler 7.

[0051] In the present invention, through heat integration and optimization, steam consumption is reduced, energy consumption is lowered, the heat of CO2 condensation is recovered, the utilization rate of waste heat is improved, the solvent regeneration efficiency is increased, and the absorption efficiency is enhanced. By introducing heat integration optimization technology, heat energy recovery and low-temperature heat upgrading are carried out on the carbon capture system, effectively reducing the consumption of high-quality steam and lowering the overall energy consumption.

[0052] A specific example provided by the present invention includes: recovering industrial waste heat or low-grade steam as the heat source of the main heat pump, and upgrading the low-temperature heat source of 60–90°C to 90–110°C, reducing the use of high-temperature steam. Adopting this main heat pump setting can further reduce the external heating demand, reduce steam consumption by 20–40%, and lower the operating cost.

[0053] The auxiliary heat pump recovers the CO2 condensation heat in the regeneration gas flue of the desorption tower. During the CO2 desorption process, about 30–40% of the input energy is wasted in the form of heat (such as high-temperature water vapor in the exhaust gas, heat exchanger losses, etc.). The auxiliary heat pump can recover heat (usually 80–100°C) from the CO2 emission gas at the regeneration gas outlet at the top of the desorption tower, which is used to preheat the solvent or heat the solvent at the bottom of the desorption tower, reducing additional energy input. The heat energy recovery rate is increased by 15–30%, reducing environmental heat loss and improving energy efficiency.

[0054] Heat pump + low-temperature solvent regeneration: Due to the insufficient regeneration ability of low-temperature solvents, the traditional steam heating method is not well-matched, which is prone to overheating or efficiency loss.

[0055] The present invention adopts a dual heat pump setting of a main heat pump + an auxiliary heat pump, which can stably provide a precisely controlled low-temperature heat source (80–100°C), keep the low-temperature solvent in the best regeneration state, improve the CO2 release efficiency, reduce solvent degradation at the same time, make the low-temperature amine solvent technology more feasible, and optimize the CO2 desorption efficiency.

[0056] Among them, the heat pump is similar to the working mode of an air conditioner or a refrigerator. Through components such as a compressor, an evaporator, a condenser, and an expansion valve, low-temperature heat recovery + high-temperature heat upgrading are realized, thereby improving the utilization rate of heat energy.

[0057] In summary, the present invention adopts: a thermally integrated two-stage heat pump (main heat pump + auxiliary heat pump): two-stage compression is adopted to gradually raise the low-temperature heat energy to the high temperature required by the regeneration tower, further reducing steam consumption.

[0058] A thermally integrated optimized carbon dioxide capture system is installed at the bottom and top of the desorption tower to assist in heating the solvent, reducing steam consumption and recovering the CO2 condensation heat, thereby improving efficiency. The main heat pump is installed at the bottom of the regeneration tower and connected to industrial waste heat to reduce steam consumption. The auxiliary heat pump is installed at the top of the desorption tower to recover the CO2 condensation heat.

[0059] It is applicable to deep waste heat recovery + optimization of low-temperature regenerated solvent.

[0060] Heat pump-assisted solvent regeneration: The regeneration of traditional amine solutions (such as MEA) requires 100–120 °C, and the main heat pump can regenerate the solvent with a low-temperature heat source of 80–90 °C, which reduces the boiler steam demand and improves the waste heat utilization efficiency.

[0061] Heat pump + thermal integration optimization: Combining with a heat exchange network, the waste heat of the high-temperature desorption tower is recovered, and the temperature is raised by the auxiliary heat pump for recycling, which can reduce the regeneration energy consumption of the entire carbon capture system by 20–40%.

[0062] Industrial waste heat utilization: The main heat pump can recover low-temperature heat sources from flue gas, cooling water, compressed air exhaust, etc., improving the system economy.

[0063] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principles of the present disclosure. However, the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also considered within the protection scope of the present disclosure.

Claims

1. A heat-integrated optimized carbon dioxide capture system, characterized in that, Comprising: An absorption tower provided with a flue gas inlet, a lean liquid inlet, and a rich liquid outlet; A desorption tower provided with a rich liquid inlet, a lean liquid outlet, and a re - generated gas outlet arranged at the top of the desorption tower and communicating with the re - generated gas flue; A lean liquid pump arranged in the lean liquid pipeline between the lean liquid inlet and the lean liquid outlet; A rich liquid pump arranged in the rich liquid pipeline between the rich liquid outlet and the rich liquid inlet; A reboiler arranged in the desorption tower for the rich liquid in the desorption tower; A main heat pump, the input end of the main heat pump is connected to industrial waste heat, and the output end of the main heat pump communicates with the reboiler and provides heat source; An auxiliary heat pump, the input end of the auxiliary heat pump communicates with the re - generated gas outlet, and the output end of the auxiliary heat pump communicates with the input end of the main heat pump; Wherein, the capture system is configured to recover the waste heat in the re - generated gas in the desorption tower through the auxiliary heat pump, and the main heat pump uses the industrial waste heat to gradually increase the temperature in the desorption tower.

2. The heat-integrated optimized carbon dioxide capture system according to claim 1, wherein Further comprising: A heat exchanger respectively connected to the lean liquid pipeline and the rich liquid pipeline, and the heat exchanger is used for heat exchange between the lean liquid and the rich liquid in the lean liquid pipeline and the rich liquid pipeline.

3. The heat-integrated optimized carbon dioxide capture system according to claim 1, wherein Further comprising: A cooler arranged in the lean liquid pipeline and arranged downstream of the lean liquid pump.

4. The thermally integrated optimized carbon dioxide capture system according to claim 1, wherein The auxiliary heat pump includes an auxiliary compressor communicating with the re - generated gas outlet, and an auxiliary condenser connected to the auxiliary compressor, and the auxiliary condenser is used to exchange the heat in the gas heated by the auxiliary compressor to the main heat pump.

5. The thermally integrated optimized carbon dioxide capture system according to claim 1, wherein The main heat pump includes a main compressor communicating with the auxiliary heat pump, and a main condenser connected to the main compressor, and the main condenser is used to exchange the heat in the gas heated by the main compressor to the reboiler.

6. The thermally integrated optimized carbon dioxide capture system according to claim 1, characterized in that, Further comprising: A first flow control valve arranged in the pipeline between the input end of the auxiliary heat pump and the re - generated gas outlet.

7. The thermally integrated optimized carbon dioxide capture system according to claim 1, wherein Further comprising: A second flow control valve arranged in the pipeline between the output end of the main heat pump and the reboiler.

8. The thermally integrated optimized carbon dioxide capture system according to claim 1, characterized in that, In the direction from the bottom to the top of the absorption tower, the rich liquid outlet, the flue gas inlet, and the lean liquid inlet are arranged at intervals in sequence.

9. The thermally integrated optimized carbon dioxide capture system according to claim 1, wherein In the direction from the bottom to the top of the desorption tower, the lean liquid outlet, the rich liquid inlet, and the re - generated gas outlet are arranged at intervals in sequence.

10. The thermally integrated optimized carbon dioxide capture system according to claim 1, wherein Both the reboiler and the main heat pump are arranged at the bottom of the desorption tower, wherein the pipeline connecting the output end of the main heat pump is inserted into the desorption tower and communicates with the reboiler.

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