System for utilizing waste heat of intermediate liquid at top of desorption tower

Abstract

The utility model discloses a waste heat utilization system for intermediate liquid at the top of a desorption tower. The waste heat utilization system comprises the desorption tower, a waste heat recovery device, an intermediate tower tray and a reboiler, a first material pipeline is led out from the middle tray to enter a waste heat recovery device, and enters a reboiler after being heated, so that the middle tray of the desorption tower, the waste heat recovery device and the reboiler are sequentially communicated to form a waste heat recovery heating loop; the tower top of the desorption tower enters the waste heat recovery device through a third material pipeline, and enters the tower top condenser after being cooled by the waste heat recovery device, so that the desorption tower is sequentially communicated with the waste heat recovery device and the tower top condenser to form a waste heat recovery cooling loop. According to the waste heat utilization system, on one hand, waste heat of steam at the tower top is recycled, the waste heat discharge amount of the system is reduced, on the other hand, an intermediate liquid material is heated, low-grade waste heat is used for replacing a high-temperature heat source of the reboiler at the tower bottom through the waste heat recycling device, the process steam consumption of the reboiler at the tower bottom of the desorption tower is reduced, and a large amount of steam is saved.

Description

Technical Field

[0001] The utility model relates to the technical field of distillation, in particular to a system for utilizing waste heat of an intermediate liquid at the top of a desorption tower. Background Art

[0002] CCUS stands for Carbon Capture, Utilization and Storage, and it refers to a combination of technologies used to reduce carbon dioxide emissions from the atmosphere. These technologies can be divided into several stages:

[0003] Carbon Capture: In this phase, carbon dioxide is captured from industrial processes or directly from the air. Typically, this is achieved through methods such as chemical absorption, physical adsorption, or membrane separation.

[0004] Carbon Utilization: The captured CO2 can be used as a feedstock to make chemicals, fuels, or other products. It can also be used for enhanced oil recovery (EOR), which is to increase oil production by injecting CO2 into underground reservoirs.

[0005] Carbon Storage: Unused CO2 can be stored long-term in suitable geological formations, such as depleted oil and gas fields or deep saline aquifers, to ensure it is not released back into the atmosphere.

[0006] For the carbon capture stage, an absorption tower and a desorption tower are usually used, such as Figure 1 As shown, CO2-rich gas enters the bottom of the absorption tower. Lean amine liquid, acting as the absorption liquid, is sprayed downward, absorbing the CO2 and converting it into rich amine liquid. This is then transferred to the desorption tower for desorption and circulation. The CO2 gas separated at the top of the desorption tower, at approximately 88°C, is directly cooled to approximately 40°C using a large amount of circulating water in an overhead condenser before being discharged. During this process, approximately 70% of the energy input to the bottom reboiler is dissipated by the circulating cooling water at the top of the tower. This energy cannot be further recycled, resulting in very low heat utilization efficiency in conventional desorption towers. Research on energy-saving technologies for desorption tower distillation should be given priority. The desorption tower distillation process is a continuous evaporation-condensation process. The condensation of the gas phase at the top of the tower releases latent heat, while the evaporation of the liquid phase at the bottom requires latent heat. Combined with the working principle of heat pumps, heat pump technology is clearly a very suitable energy-saving technology for single-tower desorption tower distillation. The use of heat pumps in the distillation process can significantly improve energy utilization and enhance economic efficiency.

[0007] In view of the above, it is necessary to propose a waste heat utilization system for the intermediate liquid at the top of the desorption tower to solve the above problems. Utility Model Content

[0008] The purpose of the utility model is to overcome the defects in the prior art and provide a system for utilizing the waste heat of the intermediate liquid at the top of a desorption tower.

[0009] To achieve the above-mentioned purpose, the technical solution of the present invention is as follows: a system for utilizing waste heat of an intermediate liquid at the top of a desorption tower, comprising a desorption tower, a waste heat recovery device, an intermediate tray, and a reboiler;

[0010] The intermediate tray is any tray in the stripping section of the desorption tower, and the intermediate tray is drained out of the first material pipeline into the waste heat recovery device, and after being heated by the waste heat recovery device, it enters the reboiler through the second material pipeline, so that the intermediate tray of the desorption tower, the waste heat recovery device, and the reboiler are connected in sequence to form a waste heat recovery and heating circuit;

[0011] The top of the desorption tower enters the waste heat recovery device through the No. 3 material pipeline, and enters the top condenser after being cooled by the waste heat recovery device, so that the desorption tower is connected with the waste heat recovery device and the top condenser in sequence to form a waste heat recovery cooling loop.

[0012] Furthermore, the waste heat recovery device is an absorption heat pump device, which includes an absorber, a generator, a condenser, and an evaporator;

[0013] The waste heat recovery heating circuit is introduced into the absorber through the No. 1 material pipeline, and flows out of the absorber and is sent to the condenser through the W2 pipeline, and is connected to the No. 2 material pipeline through the W3 pipeline after passing through the condenser.

[0014] Furthermore, the waste heat recovery cooling loop is connected to the No. 3 material pipeline to the W4 pipeline and leads to the evaporator, flows out through the W5 pipeline after passing through the evaporator and is connected to the tower top condenser.

[0015] Furthermore, a driving heat source is introduced into the generator through the S1 pipeline and flows out through the S2 pipeline. In actual use, the driving heat source is steam. The absorber and the generator are connected through a solution circulation loop. The solution circulation loop is transported from the absorber to the generator through a dilute solution pipeline via a solution pump, and the generator is connected to the absorber through a concentrated solution pipeline.

[0016] Furthermore, an intermediate liquid circulation pump is provided on the waste heat recovery heating circuit, the inlet of the intermediate liquid circulation pump is connected to the intermediate tower plate side, and the outlet is connected to the absorber side; a first diversion jumper is connected between the front of the intermediate liquid circulation pump and the reboiler, and a first diversion valve is provided on the first diversion jumper.

[0017] Furthermore, the No. 3 material pipeline is connected by a second diverter jumper before and after entering and exiting the waste heat recovery device, and a second diverter valve is provided on the second diverter jumper.

[0018] Furthermore, the waste heat recovery device is provided with at least one group.

[0019] Furthermore, the desorption tower is provided with multiple outflow tower trays and multiple reflux tower trays, and the multiple outflow tower trays are respectively provided with liquid outlet pipes, and the multiple liquid outlet pipes are arranged in parallel and connected to the No. 1 material pipe; the multiple reflux tower trays are respectively provided with reflux pipes, and the multiple reflux pipes are arranged in parallel and connected to the No. 2 material pipeline; in the desorption tower, the outflow tower tray is arranged on the upper side of the reflux tower tray.

[0020] Furthermore, each liquid outlet pipe is provided with a liquid outlet control valve, and each return pipe is provided with a return flow control valve; either the liquid outlet control valve or the return flow control valve is selectively opened.

[0021] The advantages and beneficial effects of the present invention are as follows: the present invention provides a waste heat utilization system for the intermediate liquid at the top of the desorption tower. On the one hand, it recovers the waste heat of the steam at the top of the tower, reducing the waste heat emission of the system. On the other hand, it heats the intermediate liquid material. The waste heat recovery device utilizes low-grade waste heat to replace the high-temperature heat source of the reboiler at the bottom of the tower, thereby reducing the process steam consumption of the reboiler at the bottom of the desorption tower and saving a lot of steam. Compared with the conventional method of directly heating the bottom liquid with the waste heat of the steam at the top of the tower, this process design uses waste heat to heat the intermediate liquid. The temperature of the intermediate liquid is lower than that of the heat source of the bottom liquid, which is beneficial to the operation of the heat pump and effectively improves the thermal efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a flow chart of carbon capture of carbon dioxide by chemical absorption in the prior art;

[0023] Figure 2 This is a simplified schematic diagram of a waste heat utilization system for intermediate liquid at the top of a desorption tower of the utility model;

[0024] Figure 3 This is a schematic diagram of the medium flow direction of the waste heat recovery device in the utility model;

[0025] Figure 4 This is a specific schematic diagram of a waste heat utilization system for intermediate liquid at the top of a desorption tower of the utility model;

[0026] Figure 5 This is a flow chart of the second embodiment of the present utility model;

[0027] In the figure: 1. Absorption tower; 2. Desorption tower; 3. Lean amine solution; 4. Rich amine solution; 5. Top condenser; 6. Reboiler; 7. Waste heat recovery device; 8. Intermediate tray; 9. Material pipeline No. 1; 10. Material pipeline No. 2; 11. Waste heat recovery heating circuit; 12. Waste heat recovery cooling circuit; 13. Absorber; 14. Generator; 15. Condenser; 16. Evaporator; 17. W2 pipeline; 18. W3 pipeline; 19. Material pipeline No. 3; 20. W 4 pipelines; 21, W5 pipeline; 22, S1 pipeline; 23, S2 pipeline; 24, solution circulation loop; 25, solution pump; 26, dilute solution pipeline; 27, concentrated solution pipeline; 28, intermediate liquid circulation pump; 29, first diverter jumper; 30, first diverter valve; 31, second diverter jumper; 32, second diverter valve; 33, outflow tray; 34, return tray; 35, liquid outlet pipe; 36, return pipe; 37, liquid outlet control valve; 38, return control valve. DETAILED DESCRIPTION

[0028] The following embodiments are used to further describe the specific embodiments of the present invention in conjunction with the accompanying drawings and examples. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0029] The purpose of the carbon dioxide capture process is to recover the carbon dioxide in the exhaust gas of the self-owned power plant, realize the capture of carbon dioxide, realize the recovery value, and reduce carbon emissions. The basic process is as follows: Figure 1 As shown, it is carried out by chemical absorption method, which means that chemical solvent absorbs carbon dioxide by chemical reaction with CO2. When external conditions such as temperature or pressure change, the reaction is reversed, thereby achieving the purpose of carbon dioxide analysis and recycling of absorbent. Figure 1 As shown in the figure, after desulfurization and denitrification, the flue gas enters absorption tower 1 from the bottom through an induced draft fan. At the same time, absorption liquid is sprayed down from the top of absorption tower 1. The flue gas and absorption liquid come into contact within absorption tower 1 and react. The absorption liquid absorbs the CO2 in the flue gas and becomes a rich liquid containing a large amount of CO2. The rich liquid passes through a rich liquid pump and reaches desorption tower 2. In desorption tower 2, it is heated to 100 to 120°C by a reboiler 6, causing the rich liquid to decompose and release the CO2 absorbed in the flue gas, ultimately achieving the separation and recovery of carbon dioxide. In industry, alkaline chemical absorption liquids such as alcoholamines, potash, and ammonia are commonly used to absorb CO2. Currently, the more mature chemical absorption processes are mostly based on ethanolamine aqueous solutions, such as the monoethanolamine process (MEA process), the diethanolamine process (DEA process), and the methyldiethanolamine process (MDEA process).

[0030] Currently, it is the most widely used method for capturing CO2 in industry, but the absorption and analysis process requires continuous heat exchange, resulting in high steam energy consumption.

[0031] Example 1:

[0032] like Figure 2-4 As shown, a system for utilizing waste heat from the top of a desorption tower 2 for intermediate liquid is designed to recover lean amine liquid 3 and heat from the top steam of the desorption tower to heat the intermediate liquid, thereby reducing steam consumption in the desorption tower. The system includes a desorption tower 2, a waste heat recovery device 7, an intermediate tray 8, and a reboiler 6.

[0033] The intermediate tray 8 can be any tray in the stripping section of the desorption tower 2. In this embodiment, the intermediate liquid refers to the amine liquid on a tray at the bottom of the desorption tower 2 near the reboiler 6. A line of amine liquid is drawn from this tray, hereinafter referred to as the intermediate liquid, and has a temperature of 101°C. In the original process design, the intermediate tray 8 enters the reboiler 6 after descending, and the temperature of this intermediate liquid is 101°C. In this embodiment, the feed temperature of this portion is increased to further reduce the steam consumption of the desorption tower. In the prior art, there is also a method of directly forcing the bottom liquid to circulate into the waste heat recovery device 7 for heating to realize the utilization of waste heat from the top of the tower. Firstly, due to the large temperature difference between the top and bottom, in actual use, it is found that the heat utilization rate of the heat pump is limited. Secondly, the heating effect of the bottom of the tower is poor before and after the liquid is drawn from the bottom of the tower into the heat pump and then refluxed to the bottom of the tower. The improved drawn-out intermediate liquid in this embodiment is heated and sent to the tower kettle by utilizing waste heat, which can intuitively reflect the heating effect of waste heat utilization, and the temperature of the heated heat source is reduced, which is beneficial to the operation of the heat pump and effectively improves the thermal efficiency.

[0034] Specifically, such as Figure 1 As shown, the material No. 1 pipe 9 is drawn out from the middle tray 8 and enters the waste heat recovery device 7, and after being heated by the waste heat recovery device 7, enters the reboiler 6 through the No. 2 material pipe 10, so that the middle tray 8, the waste heat recovery device 7 and the reboiler 6 of the desorption tower 2 are connected in sequence to form a waste heat recovery heating circuit 11; this is to use the heat of the low-grade heat source absorbed in the waste heat recovery device 7 to heat the relatively high-grade heat source. In this embodiment, the No. 1 material pipe is an unheated high-grade heat source, which becomes a heated high-grade heat source after passing through the waste heat recovery device 7 and is sent out through the No. 2 material pipe 10 and converges into the reboiler 6, thereby effectively reducing the heat load of the reboiler 6, thereby reducing the steam usage in the tower bottom.

[0035] The low-grade heat source is the steam waste heat of the carbon dioxide at the top of the desorption tower 2. Specifically, the top of the desorption tower 2 enters the waste heat recovery device 7 through the No. 3 material pipe 19. Before entering the waste heat recovery device 7, it is a low-grade heat source with a relatively high temperature. After passing through the waste heat recovery device 7, the heat in the low-grade heat source is converted into a high-grade heat source by the waste heat recovery device 7, thereby further reducing the temperature of the low-grade heat source. Specifically, the temperature of the No. 3 material pipe is 86-88°C before entering the waste heat recovery device 7, and the temperature after flowing out is reduced to 70°C; the pipeline setting after cooling through the waste heat recovery device 7 is the same as the original design, and still enters the top condenser 5. After cooling, it is reduced to about 40°C. In comparison, the cooling load of the top condenser 5 is also effectively reduced. In this embodiment, the desorption tower 2 is connected with the waste heat recovery device 7 and the top condenser 5 in sequence to form a waste heat recovery cooling circuit 12.

[0036] like Figure 3 As shown, the waste heat recovery device 7 in this embodiment is an absorption heat pump device, specifically including an absorber 13, a generator 14, a condenser 15, and an evaporator 16. The absorber 13 and the generator 14 are connected via a solution circulation loop 24. The solution circulation loop 24 is transported from the absorber 13 to the generator 14 via a dilute solution line 26 via a solution pump 25. The generator 14 is connected to the absorber 13 via a concentrated solution line 27. The solvent is continuously circulated between the absorber 13 and the generator 14 by the solution pump 25 to form the solution circulation loop 24.

[0037] The working fluid within the waste heat recovery and conversion system is lithium bromide solution, which serves as the absorbent for the lithium bromide absorption cooling / heating unit. Physical properties of lithium bromide solution: Name: Lithium Bromide; Chemical Formula: LiBr; Molecular Weight: 86.85; Physical Properties: Extremely deliquescent. Appearance: White cubic crystals or granular powder; Density: 3.64 g / cm³; Melting Point: 560°C; Boiling Point: 1265°C. Solubility: Freely soluble in water, ether, and ethanol; soluble in organic solvents such as methanol, acetone, and ethylene glycol; slightly soluble in pyridine. Its aqueous solution is highly hygroscopic. Furthermore, at room temperature, the concentration of a saturated lithium bromide aqueous solution reaches 60%. The higher the concentration and the lower the temperature, the greater the hygroscopicity.

[0038] In this embodiment, the waste heat recovery heating circuit 11 is introduced into the absorber 13 via the No. 1 material pipeline 9. From the absorber 13, it flows through the W2 pipeline 17 into the condenser 15. After passing through the condenser 15, it is connected to the No. 2 material pipeline 10 via the W3 pipeline 18. Specifically, the heated high-grade heat source flows sequentially through the absorber 13 and the condenser. After undergoing secondary heating, in this embodiment, the high-grade heat source is heated from approximately 101°C to approximately 110°C. Separately, the low-grade heat source flows through the waste heat recovery cooling circuit 12, which connects to the W4 pipeline 20 and leads to the evaporator 16. After passing through the evaporator 16, it flows out through the W5 pipeline 21 and connects to the overhead condenser 5. The water in the evaporator 16 evaporates, absorbing heat, lowering the temperature of the low-grade heat source. This heat is then transferred to the water vapor, which is then fed into the absorber 13. In this embodiment, the low-grade heat source has an initial temperature of approximately 88°C, and its temperature drops to approximately 70°C after exiting. Furthermore, a driving heat source is introduced into the generator 14 through the S1 pipe 22 and flows out through the S2 pipe 23. In actual use, the driving heat source is steam.

[0039] Furthermore, an intermediate liquid circulation pump 28 is provided on the waste heat recovery heating circuit 11, the inlet of the intermediate liquid circulation pump 28 is connected to the side of the intermediate tower plate 8, and the outlet is connected to the side of the absorber 13; the intermediate liquid is forced to circulate through the intermediate liquid circulation pump 28: the pressure is increased by a booster pump and then sent to the absorption heat pump component, and after the temperature is increased, it enters the reboiler 6, thereby achieving the purpose of reducing steam consumption.

[0040] like Figure 2 、 4 As shown, a first splitter jumper 29 is connected between the intermediate liquid circulation pump 28 and the reboiler 6, and a first splitter valve 30 is installed on the first splitter jumper 29. The first splitter jumper 29 can be used to adjust the flow entering the absorption heat pump assembly, and the flow is controlled by the first splitter valve 30. Similarly, the No. 3 material pipeline 19 is connected before and after entering and exiting the waste heat recovery device 7 through a second diverter jumper 31. A second diverter valve 32 is provided on the second diverter jumper 31. During actual use, if there is a problem with the waste heat recovery device 7 and maintenance is carried out, the waste heat recovery device 7 can be cut off and isolated separately, and the top gas in the system still circulates through the second diverter jumper 31; and during normal operation, the flow entering the waste heat recovery device 7 can also be controlled by the second diverter valve 32 to control the heat energy recovery amount of the waste heat recovery system; when operating under variable conditions, the design operating conditions of this heat energy recovery system are 108→115℃ for the bottom liquid and 101→109.93℃ for the intermediate liquid; the load adjustment range can be controlled within 20~100%.

[0041] Furthermore, the waste heat recovery device 7 can be configured with only one set of recovery devices or multiple sets in parallel according to the processing capacity; in this embodiment, two sets are schematically configured in parallel. Figure 4 As shown, in actual use, multiple groups of waste heat recovery devices 7 can be set up, and the effect of increasing the processing capacity can be achieved by connecting them in parallel, and a backup unit can also be formed. Figure 4 The illustrated configuration includes two groups, specifically component 1 and component 2, which can serve as backup for each other or operate simultaneously to increase processing capacity.

[0042] The design utilizes 1.0 MPaG saturated steam as the driving energy source. After condensation in the heat recovery system, the steam is recovered and sent to the steam condensate network of the original reboiler through condensate recovery. Process steam: 1.0 MPaG saturated steam can be provided. The design is based on 1.0 MPaG saturated steam. The steam condensate is calculated at 120°C, with an effective enthalpy of 544.27 kcal / kg, which is 0.633 MW / t of steam.

[0043] Scheme design: The operating temperature of the tower bottom liquid is about 108℃, and the temperature after reboiler heating is about 115℃;

[0044] Under the existing process conditions, the heat load of the reboiler is 1.3t steam (0.3MPaG) / t CO2. Based on an annual output of 1 million tons, the steam consumption is approximately 162t / h. The heat load of the desorption tower is 100.44MW.

[0045] The top steam of the analytical tower: temperature 86~88℃, flow rate 168.292t / h, heat release when cooled to 70℃: 17MW; the final temperature needs to be cooled to 40℃.

[0046] Process principle: Recover low-grade heat energy of 20℃~70℃ and convert it into high-grade heat medium with a temperature 40℃~50℃ higher than the low-grade heat. Compared with direct heating by heat exchanger, it can save 40% of steam.

[0047] Energy-saving technical indicators:

[0048] Rated operating system parameters:

[0049] System heating capacity: 100.44MW - equivalent to 162t / h of 0.3MPaG saturated steam and 158.67t / h of 1.0MPaG saturated steam; waste heat recovery capacity is 30MW, approximately 47.39t / h of 1.0MPaG saturated steam.

[0050] Driving steam: 1.0 MPaG saturated steam, consumption 111.28 t / h, steam condensate temperature 120°C;

[0051] Intermediate liquid: flow rate 4000t / h, temperature 101→109.93℃;

[0052] Bottom liquid: temperature 108→115℃ (same as reboiler operating conditions), flow rate is about 7580t / h;

[0053] Desorption tower top steam: temperature 88→70℃, 17MW

[0054] Lean amine liquid: temperature 61→56℃, heat load 14.75MW, flow rate 2674t / h, flow rate share about 70.4%;

[0055] Reduce circulating water consumption: 3225t / h (according to 30→38℃), and reduce cooling tower water replenishment by an average of 45t / h;

[0056] System consumption: approximately 1600kW; (This is an estimated value. The selection parameters of the tower bottom liquid can only be determined after the physical properties are determined.)

[0057] Table 1 Main operating parameters before and after energy-saving transformation

[0058]

[0059] Economic benefit analysis:

[0060] Table 2 Economic Benefit Analysis Calculation Table (1 million tons / year CCUS)

[0061]

[0062] Example 2:

[0063] In order to improve the temperature control range of the waste heat utilization system, as an improvement, Figure 5As shown, the desorption tower 2 is provided with a plurality of outflow trays 33 and a plurality of reflux trays 34, and liquid outlet pipes 35 are respectively provided on the plurality of outflow trays 33, and the plurality of liquid outlet pipes 35 are arranged in parallel and connected to the No. 1 material pipe. In actual use, any liquid outlet pipe 35 can be opened, and the liquid outlet pipe 35 is the liquid outlet of the middle tray 8; and at the same time, the plurality of reflux trays are respectively provided with reflux pipes 36, and the plurality of reflux pipes 36 are arranged in parallel and connected to the No. 2 material pipeline 10; the outflow tray 33 in the desorption tower 2 is arranged on the upper side of the reflux tray 34. During actual control, since the temperature after passing through the waste heat utilization system, i.e., the discharge temperature of the No. 2 material pipeline 10, will change with the change of the feed amount and the change of the flow rate entering the waste heat recovery device 7, the temperature will change. In the first embodiment, no matter how much the temperature is heated, it is directly sent to the tower kettle. This may cause large fluctuations in the tower kettle temperature, which may have a greater impact on the steady state of the entire desorption tower 2. In this embodiment, in order to avoid this situation, according to the temperature monitoring of the No. 2 material pipeline 10, it is sent to the appropriate return tower tray 34. It can be understood that the temperature of the material on the return tower tray 34 is It is better to be closer to the temperature of the No. 2 material pipe. Furthermore, each liquid outlet pipe 35 is provided with a liquid outlet control valve 37, and each return pipe 36 is provided with a return control valve 38; the liquid outlet control valve 37 and the return control valve 38 are opened at one of them; in actual use, any liquid outlet control valve 37 can be opened by remote control, and different outflow tower plates 33 can be selected to discharge liquid, so as to achieve controllability of the temperature control range; and the material flowing out of the No. 2 material pipeline 10 is sent to the return tower plate 34 with the closest temperature, so that the waste heat of the entire desorption tower 2 can be effectively utilized, and the overall operation of the system is more stable.

[0064] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A system for utilizing waste heat from the top of a desorption tower for intermediate liquid, characterized in that: It includes a desorption tower (2), a waste heat recovery device (7), an intermediate tower tray (8), and a reboiler (6); The intermediate tray (8) is any tray in the stripping section of the desorption tower (2), and the intermediate tray (8) is drained out of the first material pipeline (9) into the waste heat recovery device (7), and after being heated by the waste heat recovery device (7), enters the reboiler (6) through the second material pipeline (10), so that the intermediate tray (8), the waste heat recovery device (7), and the reboiler (6) of the desorption tower (2) are connected in sequence to form a waste heat recovery heating circuit (11); The top of the desorption tower (2) enters the waste heat recovery device (7) through the No. 3 material pipeline (19), and enters the top condenser (5) after being cooled by the waste heat recovery device (7), so that the desorption tower (2) is connected with the waste heat recovery device (7) and the top condenser (5) in sequence to form a waste heat recovery cooling circuit (12).

2. The system for utilizing waste heat from the top of a desorption tower to an intermediate liquid according to claim 1, characterized in that: The waste heat recovery device (7) is an absorption heat pump device, which includes an absorber (13), a generator (14), a condenser (15), and an evaporator (16); The waste heat recovery heating circuit (11) is introduced into the absorber (13) through the No. 1 material pipeline (9), and flows out of the absorber (13) and is sent to the condenser (15) through the W2 pipeline (17). After passing through the condenser (15), it is connected to the No. 2 material pipeline (10) through the W3 pipeline (18).

3. The waste heat utilization system for the intermediate liquid at the top of a desorption tower according to claim 2, characterized in that: The waste heat recovery cooling circuit (12) is connected to the No. 3 material pipeline (19) through the W4 pipeline (20) and leads to the evaporator (16). After passing through the evaporator (16), it flows out through the W5 pipeline (21) and is connected to the tower top condenser (5).

4. The system for utilizing waste heat from the top of a desorption tower to an intermediate liquid according to claim 3, characterized in that: A driving heat source is introduced into the generator (14) through the S1 pipeline (22) and flows out through the S2 pipeline (23). The absorber (13) and the generator (14) are connected through a solution circulation loop (24). The solution circulation loop (24) is transported from the absorber (13) through a dilute solution pipeline (26) and a solution pump (25) to the generator (14). The generator (14) is connected to the absorber (13) through a concentrated solution pipeline (27).

5. The system for utilizing waste heat from the top of a desorption tower to an intermediate liquid according to claim 2, characterized in that: An intermediate liquid circulation pump (28) is provided on the waste heat recovery heating circuit (11), the inlet of the intermediate liquid circulation pump (28) is connected to the side of the intermediate tower tray (8), and the outlet is connected to the side of the absorber (13); a first diverter jumper (29) is connected between the front of the intermediate liquid circulation pump (28) and the reboiler (6), and a first diverter valve (30) is provided on the first diverter jumper (29).

6. The system for utilizing waste heat from the top of a desorption tower to an intermediate liquid according to claim 3, characterized in that: The No. 3 material pipeline (19) is connected before and after entering and exiting the waste heat recovery device (7) via a second diverter jumper (31), and a second diverter valve (32) is provided on the second diverter jumper (31).

7. The system for utilizing waste heat from the top of a desorption tower to an intermediate liquid according to claim 1, characterized in that: The waste heat recovery device (7) is provided with at least one group.

8. The system for utilizing waste heat from the top of a desorption tower to an intermediate liquid according to claim 1, characterized in that: The desorption tower (2) is provided with a plurality of outflow trays (33) and a plurality of return trays (34), and the plurality of outflow trays (33) are respectively provided with liquid outlet pipes (35), and the plurality of liquid outlet pipes (35) are arranged in parallel and connected to the No. 1 material pipe; the plurality of return trays are respectively provided with return pipes (36), and the plurality of return pipes (36) are arranged in parallel and connected to the No. 2 material pipe (10); in the desorption tower (2), the outflow tray (33) is arranged on the upper side of the return tray (34).

9. The system for utilizing waste heat from the top of a desorption tower to an intermediate liquid according to claim 8, characterized in that: Each liquid outlet pipe (35) is provided with a liquid outlet control valve (37), and each return pipe (36) is provided with a return flow control valve (38); either the liquid outlet control valve (37) or the return flow control valve (38) is selectively opened.

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