Desorption tower kettle liquid waste heat utilization system based on absorption heat pump principle

Abstract

The invention discloses a desorption tower kettle liquid waste heat utilization system based on an absorption heat pump principle. A tower kettle liquid circulation loop comprises a first material pipe which is led out from a desorption tower kettle, serves as a heated high-grade heat source and is connected to a waste heat utilization device; the waste heat flows out of the waste heat utilization device and is connected to the tower kettle through a second material pipe to form a closed loop; the barren amine liquid circulation loop comprises a barren liquid pipeline for pumping materials from the tower kettle of the desorption tower to the tower top of the absorption tower, and the barren liquid pipeline comprises a third material pipe entering the waste heat utilization device and a fourth material pipe flowing out of the waste heat utilization device. According to the desorption tower kettle liquid waste heat utilization system, on one hand, waste heat of lean amine liquid is recycled, the use amount of circulating water is reduced, on the other hand, low-grade heat sources in the lean amine liquid are recycled, materials in a desorption tower kettle are heated, low-grade waste heat is used for replacing a high-temperature heat source of a tower bottom reboiler through the waste heat recovery device, and the desorption tower kettle liquid waste heat utilization efficiency is improved. The process steam consumption of the reboiler at the bottom of the desorption tower is reduced, and a large amount of steam is saved.

Description

Technical Field

[0001] The invention relates to the technical field of waste heat utilization, and in particular to a desorption tower bottom liquid waste heat utilization system based on the absorption heat pump principle. Background Art

[0002] CCUS is the abbreviation of Carbon Capture, Utilization and Storage, which refers to a combination of technologies used to reduce carbon dioxide emissions in 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 can be achieved through methods such as chemical absorption, physical adsorption or membrane separation.

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

[0005] Carbon Storage: For unused CO2, it can be stored for a long time in suitable geological formations, such as depleted oil and gas fields or deep saline aquifers. The purpose is to ensure that the CO2 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, the gas rich in carbon dioxide enters from the bottom of the absorption tower, and the lean amine liquid is sprayed from top to bottom as the absorption liquid, absorbing carbon dioxide and converting it into rich amine liquid, and then transporting it to the desorption tower for desorption and circulation; before the lean amine liquid at the bottom of the desorption tower passes through the lean and rich amine liquid heat exchanger and enters the lean amine cooler, there is still a low-grade heat source of about 60°C that is not utilized. In the prior art, the lean liquid cooler is directly cooled to about 40°C and sent to the absorption tower, so that this part of the heat is brought into the circulating water. This part of the energy cannot be further recycled, resulting in a very low heat utilization efficiency in the carbon capture process. Research on energy-saving technology in the carbon capture process should be taken seriously. In the carbon capture process, the lean liquid cooler takes away the low-grade heat source, and the evaporation of the liquid phase at the bottom of the desorption tower requires latent heat. Combined with the working principle of the heat pump, for this process, the heat pump technology is obviously a very suitable energy-saving technology, which greatly improves the energy utilization rate and economy in the carbon capture process.

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

[0008] The purpose of the present invention is to overcome the defects in the prior art and provide a desorption tower bottom liquid waste heat utilization system based on the absorption heat pump principle.

[0009] To achieve the above object, the technical solution of the present invention is as follows: a desorption tower bottom liquid waste heat utilization system based on the absorption heat pump principle, comprising a desorption tower, a waste heat utilization device, a bottom liquid circulation loop, and a lean amine liquid circulation loop; The tower bottom liquid circulation loop includes a first material pipe drawn from the tower bottom of the desorption tower as a high-grade heat source to be heated and connected to a waste heat utilization device, flowing out from the waste heat utilization device and connected to the tower bottom through a second material pipe to form a closed loop; The lean amine liquid circulation loop includes a lean liquid pipeline for pumping materials from the bottom of the desorption tower to the top of the absorption tower, and the lean liquid pipeline includes a third material pipe entering the waste heat utilization device and a fourth material pipe flowing out of the waste heat utilization device.

[0010] Furthermore, the waste heat utilization device is an absorption heat pump device, which includes an absorber, a generator, a condenser, and an evaporator; a solvent circulation loop is formed between the absorber and the generator, and a solution pump is provided on the solvent circulation loop; the generator is connected to the condenser and a first gas pipeline is provided; the condenser is connected to the evaporator and a throttling pipeline is provided, and a throttling valve is provided on the throttling pipeline; the evaporator is connected to the absorber and a second gas pipeline is provided; the generator is connected to a driving heat source pipeline.

[0011] Furthermore, the waste heat utilization device includes a plurality of absorption heat pump devices arranged in parallel, the first material pipeline forms a plurality of branches and is respectively connected to the W1 pipeline of the absorption heat pump device to be introduced into the absorber, connected to the condenser through the W2 pipeline, and connected to the second material pipe through the W3 pipeline; the third material pipe enters the evaporator through the W4 pipeline and flows out through the W5 pipeline.

[0012] Furthermore, the waste heat utilization device includes two groups of absorption heat pump devices, which are divided into a primary heat pump and a secondary heat pump, and an intermediate heat medium circulation loop is provided between the primary heat pump and the secondary heat pump.

[0013] Furthermore, the first material pipe is provided with a first branch pipe and a second branch pipe, the first branch pipe is connected to the absorber or condenser of the primary heat pump, the second branch pipe is connected to the secondary heat pump and passes through the absorber and the condenser in sequence, the two branch pipes converge and are connected to the second material pipe, and the third material pipe is connected to the evaporator of the primary heat pump.

[0014] Furthermore, the intermediate heat medium circulation loop is connected to the primary heat pump and the absorber or condenser different from the first branch pipe through the H1 pipeline. The intermediate heat medium circulation loop flows out from the primary heat pump through the H2 pipeline and is connected to the evaporator of the secondary heat pump, and flows back to the H1 pipeline from the secondary heat pump evaporator.

[0015] Furthermore, a heat medium circulation pump is provided on the H1 pipeline or the H2 pipeline.

[0016] Furthermore, a cross-line pipe is provided between the third material pipe and the fourth material pipe, and a cross-line regulating valve is provided on the cross-line pipe.

[0017] The advantages and beneficial effects of the present invention are as follows: the present invention is a system for utilizing waste heat of desorption tower bottom liquid based on the absorption heat pump principle, which, on the one hand, recovers the waste heat of lean amine liquid and reduces the amount of circulating water used, and on the other hand, recovers the low-grade heat source in the lean amine liquid to heat the desorption tower bottom material, and utilizes the low-grade waste heat through the waste heat recovery device to replace the high-temperature heat source of the bottom reboiler, thereby reducing the process steam consumption of the bottom reboiler of the desorption tower and saving a large amount of steam. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the basic flow chart of carbon dioxide absorption and desorption in the prior art; Figure 2 It is a simplified flow chart of waste heat utilization in the present invention; Figure 3 Schematic diagram of the working medium flow direction of the waste heat utilization device of the present invention; Figure 4 It is a detailed flow chart of waste heat utilization in the present invention; Figure 5 It is a schematic diagram of the working medium flow direction of multiple absorption heat pumps in the second embodiment of the present invention; Figure 6 It is a schematic diagram of the working medium flow direction of multiple absorption heat pumps in the third embodiment of the present invention; In the figure: 1, desorption tower; 2, absorption tower; 3, rich amine liquid; 4, lean amine liquid; 5, lean and rich amine liquid heat exchanger; 6, lean liquid cooler; 7, waste heat utilization device; 8, tower bottom liquid circulation loop; 9, lean amine liquid circulation loop; 10, first material pipe; 11, second material pipe; 12, lean liquid pipeline; 13, third material pipe; 14, fourth material pipe; 15, absorber; 16, generator; 17, condenser; 18, evaporator; 19, solvent circulation loop; 20, solution pump ; 21. First gas pipeline; 22. Throttle valve; 23. Second gas pipeline; 24. Driving heat source; 25. W1 pipeline; 26. W2 pipeline; 27. W3 pipeline; 28. W4 pipeline; 29. ​​W5 pipeline; 30. Primary heat pump; 31. Secondary heat pump; 32. Intermediate heat medium circulation loop; 33. First branch pipe; 34. Second branch pipe; 35. H1 pipeline; 36. H2 pipeline; 37. Heat medium circulation pump; 38. Cross-line pipe; 39. Cross-line regulating valve. DETAILED DESCRIPTION

[0019] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0020] The purpose of the carbon dioxide capture process is to recover the carbon dioxide in the exhaust gas of the self-provided power plant, realize carbon dioxide capture, realize recycling value, and reduce carbon emissions. The basic process is as follows Figure 1 As shown, the chemical absorption method is used. The chemical absorption method refers to the chemical solvent reacting with CO2 to absorb carbon dioxide. 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, after the flue gas is desulfurized and denitrated, the exhaust gas enters the absorption tower 2 from the bottom through the induced draft fan, and the absorption liquid sprays down from the top of the absorption tower 2. The flue gas and the absorption liquid react after contact in the absorption tower 2. The absorption liquid absorbs CO2 in the flue gas and becomes a rich liquid containing a large amount of CO2. The rich liquid passes through the rich liquid pump to the desorption tower 1. In the desorption tower 1, it is heated to 100 to 120°C by the reboiler, so that the rich liquid decomposes and releases the CO2 absorbed in the flue gas, and finally achieves the separation and recovery of carbon dioxide. The lean amine liquid 4 passes through two heat exchangers in the process of flowing from the bottom of the desorption tower 1 to the absorption tower 2, first passing through the lean and rich amine liquid 3 heat exchanger and then passing through the lean liquid cooler 6. The lean and rich amine liquid 3 heat exchanger is a mutual heat exchange between low-temperature amine liquid and high-temperature amine liquid, which is conducive to the recovery and utilization of heat, but the lean liquid cooler 6 directly uses internal cooling water to cool the lean amine liquid 4 from about 60°C to about 40°C. In this process, a large amount of heat energy is not effectively utilized.

[0021] Embodiment 1: A system for utilizing waste heat from a desorption tower 1 kettle liquid based on the absorption heat pump principle comprises a desorption tower 1, a waste heat utilization device 7, a kettle liquid circulation loop 8, and a lean amine liquid 4 circulation loop; Figure 2 , 3 As shown, the bottom liquid circulation loop 8 includes a first material pipe 10 drawn from the bottom of the desorption tower 1 as a high-grade heat source to be heated and connected to the waste heat utilization device 7, flowing out of the waste heat utilization device 7 and connected to the bottom of the tower through a second material pipe 11 to form a closed loop; in this embodiment, the bottom liquid temperature is about 110°C; the lean amine liquid 4 circulation loop includes a lean liquid pipeline 12 that pumps materials from the bottom of the desorption tower 1 to the top of the absorption tower 2, and the lean liquid pipeline 12 includes a third material pipe 13 entering the waste heat utilization device 7 and a fourth material pipe 14 flowing out of the waste heat utilization device 7. It can be understood that, in combination with the attached Figure 1 The third material pipe 13 in this embodiment is a pipeline drawn out after the heat exchanger of the lean and rich amine liquid 3, wherein the material temperature is about 60°C, and the lean amine liquid 4 is a low-grade heat source, which enters the waste heat utilization device 7, and recovers the heat through the waste heat utilization device 7 to heat the high-grade heat source-the bottom liquid of the desorption tower 1, thereby realizing the effective utilization of the low-grade heat source and improving the thermal efficiency. A cross-line pipe 38 is provided between the third material pipe 13 and the fourth material pipe 14, and a cross-line regulating valve 39 is provided on the cross-line pipe 38. The cross-line pipe 38 can adjust the flow of the low-grade heat source entering the waste heat utilization device 7, and play a role in fine regulation. It can also be used to isolate the waste heat utilization device 7 from the original carbon dioxide capture process, so that the system top condenser 17 can achieve its original function, which is conducive to the realization of the system initial start-up requirements and the need for standby use in the later operation.

[0022] Specifically, Figure 3As shown, the waste heat utilization device 7 is an absorption heat pump device, which includes an absorber 15, a generator 16, a condenser 17, and an evaporator 18; a solvent circulation loop 19 is formed between the absorber 15 and the generator 16, and a solution pump 20 is provided on the solvent circulation loop 19; the working fluid used in the absorption heat pump device is a lithium bromide aqueous solution, the absorber 15 contains a dilute lithium bromide solution, the generator 16 contains a concentrated lithium bromide solution, and the solution pump 20 is used to circulate the lithium bromide solution between the absorber 15 and the generator 16; the generator 16 is connected to the condenser 17 and is provided with a first gas pipeline 21; the generator 16 is connected to a driving heat source 24 pipeline, and the driving heat source 24 in this embodiment can be a 1.0MPaG saturated steam is used as the drive, and 0.3MPaG saturated steam can also be used for driving. The steam heats the solution in the generator 16, so that the water therein evaporates and enters the condenser 17 through the first gas pipeline 21. Water is used as the refrigerant, and condensation and heat release in the condenser 17 heat the medium passing through the condenser 17; the condenser 17 is connected to the evaporator 18 and is provided with a throttling pipeline, and a throttling valve 22 is provided on the throttling pipeline. Water enters the evaporator 18 through the throttling valve 22 to evaporate and take away the heat of the medium passing through; the evaporator 18 is connected to the absorber 15 and is provided with a second gas pipeline 23. The water vapor formed in the evaporator 18 returns to the absorber 15 through the second gas pipeline 23, so as to form a closed-loop absorption heat pump device.

[0023] In this embodiment, the waste heat utilization device 7 includes multiple groups of absorption heat pump devices arranged in parallel. Multiple groups of absorption heat pump devices can be arranged, such as Figure 2 Components 3-6 shown in the embodiment, this embodiment takes four groups of absorption heat pump devices arranged in parallel as an example, specifically, the first material pipe 10 forms a plurality of branches and is respectively connected to the W1 pipeline 25 of the absorption heat pump device and introduced into the absorber 15, specifically, the first material pipe 10 is divided into four branches, corresponding to the four groups of absorption heat pump devices, each device is introduced into the absorber 15 through the corresponding W1 pipeline 25, such as Figure 3 As shown, after flowing out from the absorber 15, it is connected to the condenser 17 through the W2 pipeline 26, and finally connected to the second material pipe 11 through the W3 pipeline 27. Therefore, it can be understood that the tower bottom liquid is forced to circulate and pump into the four absorption heat pump devices by the tower bottom liquid circulation pump, and each group of devices is heated by the absorber 15 and the condenser 17 in two stages to realize the utilization of low-grade thermal energy. Specifically, as Figure 2As shown, the outlet temperature of the tower bottom is 108°C, and after heating, the temperature rises to 115°C and is sent back to the desorption tower 1, thereby reducing the heat load of the desorption tower 1 tower bottom reboiler and reducing the amount of steam used. Furthermore, after the low-grade heat source passes through the lean-rich amine liquid 3 heat exchanger, it enters the evaporator 18 through the third material pipe 13 through the W4 pipeline 28 and flows out through the W5 pipeline 29. The lean amine liquid 4 passes through the evaporator 18, and water evaporates inside it to take away the heat of the low-grade heat source lean amine liquid 4, so that the lean amine liquid 4 is reduced from 61°C to about 56°C, thereby also reducing the cooling load of the lean liquid cooler 6 at the same time and reducing the consumption of circulating water.

[0024] Energy-saving technical indicators: Rated operating system parameters: 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, 1.0MPaG saturated steam.

[0025] Driving steam: steam 1.0MPaG saturated steam, consumption 111.28t / h, steam condensate temperature 120℃; Intermediate liquid: flow rate 4000t / h, temperature 101→109.93℃; Bottom liquid: temperature 108→115℃ (same as reboiler operation condition), flow rate is about 7580t / h; Desorption tower top steam: temperature 88→70℃, 17MW Lean amine liquid: temperature 61→56℃, heat load 14.75MW, flow rate 2674t / h, flow rate accounting for about 70.4%; Reduce circulating water consumption: 3225t / h (according to 30→38℃), and reduce cooling tower water replenishment by an average of 45t / h; System consumption: about 1600kW; (This is an estimated value. The selection parameters of the tower bottom liquid can only be determined after the physical properties are determined.)

[0026] Table 1 Main operating parameters before and after energy-saving transformation

[0027] Economic benefit analysis: Table 2 Economic benefit analysis calculation table (1 million tons / year CCUS)

[0028] Embodiment 2: In the first embodiment, a plurality of absorption heat pump devices are provided, and the lean amine liquid 4 needs to be divided into a plurality of corresponding branch pipes connected to each heat pump device, so that the process medium of the lean amine liquid 4 coming out of the desorption tower 1 is divided into a plurality of thin branches, which easily leads to an increase in the transportation resistance of the process medium to the top of the absorption tower 2; and at the same time, the process medium is divided into a plurality of thin branches, which also leads to an increased risk of pipeline leakage.

[0029] As an improvement, the waste heat utilization device 7 includes two groups of absorption heat pump devices, which are divided into a primary heat pump 30 and a secondary heat pump 31. An intermediate heat medium circulation loop 32 is provided between the primary heat pump 30 and the secondary heat pump 31. Figure 4 , 5 As shown, the first branch pipe 33 and the second branch pipe 34 branched from the first material pipe 10 are arranged in parallel, and the two branch pipes are connected to two heat pumps respectively.

[0030] The difference is that, Figure 5 As shown, the first branch pipe 33 is connected to the condenser 17 of the primary heat pump 30, the second branch pipe 34 is connected to the secondary heat pump 31, and passes through the absorber 15 and the condenser 17 in sequence, and finally the two branch pipes converge and are connected to the second material pipe 11, and flow back into the desorption tower 1; the third material pipe 13 is connected to the evaporator 18 of the primary heat pump 30. In this embodiment, the low-grade heat source is only connected to the primary heat pump 30, and is not connected to other absorption heat pump devices, so that the process medium of the lean amine liquid 4 can be concentrated to flow through the primary heat pump 30, so that the process pipeline of the desorption tower 1 kettle is simplified, and the load of the desorption tower 1 kettle pump can be reduced, so that the transportation resistance of the lean amine liquid 4 is reduced.

[0031] Specifically, the intermediate heat medium circulation loop 32 is connected to the absorber 15 of the primary heat pump 30 through the H1 pipeline 35. Since the condenser 17 in the primary heat pump 30 is connected to the first branch pipe 33, the H1 pipeline 35 is allocated to the absorber 15. The intermediate heat medium circulation loop 32 flows out from the primary heat pump 30 through the H2 pipeline 36 and is connected to the evaporator 18 of the secondary heat pump 31, and flows back to the H1 pipeline 35 from the evaporator 18 of the secondary heat pump 31, thus forming the intermediate heat medium circulation loop 32. The H1 pipeline 35 or the H2 pipeline 36 is provided with a heat medium circulation pump 37, and the intermediate heat medium is circulated and transferred between different heat pumps through the heat medium circulation pump 37. Thus, the heat of the low-quality heat source of the lean amine liquid 4 can be allocated to the secondary heat pump 31, and used as the low-quality heat source in the secondary heat pump 31. Such a setting can avoid the disadvantages of large transportation resistance and large leakage risk caused by the complicated differentiation of the lean amine liquid 4 pipeline in the tower kettle of the desorption tower 1.

[0032] Embodiment three: As another embodiment, this embodiment is substantially the same as the second embodiment, except that: Figure 6 As shown, the first branch pipe 33 is connected to the absorber 15 of the primary heat pump 30, the second branch pipe 34 is connected to the secondary heat pump 31, and passes through the absorber 15 and the condenser 17 in sequence, and finally the two branch pipes converge and are connected to the second material pipe 11, and flow back into the desorption tower 1; the third material pipe 13 is connected to the evaporator 18 of the primary heat pump 30, and the intermediate heat medium circulation loop 32 is connected to the condenser 17 of the primary heat pump 30 through the H1 pipeline 35, the intermediate heat medium circulation loop 32 flows out from the primary heat pump 30 through the H2 pipeline 36 and is connected to the evaporator 18 of the secondary heat pump 31, and flows back from the evaporator 18 of the secondary heat pump 31 to the H1 pipeline 35, thus forming the intermediate heat medium circulation loop 32.

[0033] 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 the scope of protection of the present invention.

Claims

1. A system for utilizing waste heat from desorption tower bottom liquid based on the absorption heat pump principle, characterized in that: It comprises a desorption tower (1), a waste heat utilization device (7), a tower bottom liquid circulation loop (8), and a lean amine liquid (4) circulation loop; The tower bottom liquid circulation loop (8) comprises a first material pipe (10) drawn from the tower bottom of the desorption tower (1) as a high-grade heat source to be heated and connected to the waste heat utilization device (7), and flows out of the waste heat utilization device (7) and is connected to the tower bottom through a second material pipe (11) to form a closed loop; The lean amine liquid (4) circulation loop comprises a lean liquid pipeline (12) for pumping material from the bottom of the desorption tower (1) to the top of the absorption tower (2), and the lean liquid pipeline (12) comprises a third material pipe (13) entering the waste heat utilization device (7) and a fourth material pipe (14) flowing out of the waste heat utilization device (7).

2. A desorption tower bottom liquid waste heat utilization system based on the absorption heat pump principle according to claim 1, characterized in that: The waste heat utilization device (7) is an absorption heat pump device, comprising an absorber (15), a generator (16), a condenser (17), and an evaporator (18); a solvent circulation loop (19) is formed between the absorber (15) and the generator (16), and a solution pump (20) is provided on the solvent circulation loop (19); the generator (16) is connected to the condenser (17) and is provided with a first gas pipeline (21); the condenser (17) is connected to the evaporator (18) and is provided with a throttling pipeline, and a throttling valve (22) is provided on the throttling pipeline; the evaporator (18) is connected to the absorber (15) and is provided with a second gas pipeline (23); and the generator (16) is connected to a driving heat source (24) pipeline.

3. A desorption tower bottom liquid waste heat utilization system based on the absorption heat pump principle according to claim 2, characterized in that: The waste heat utilization device (7) comprises a plurality of absorption heat pump devices arranged in parallel, wherein the first material pipe (10) forms a plurality of branches and is respectively connected to the W1 pipe (25) of the absorption heat pump device to be introduced into the absorber (15), connected to the condenser (17) via the W2 pipe (26), and connected to the second material pipe (11) via the W3 pipe (27); the third material pipe (13) enters the evaporator (18) via the W4 pipe (28), and flows out via the W5 pipe (29).

4. A desorption tower bottom liquid waste heat utilization system based on the absorption heat pump principle according to claim 2, characterized in that: The waste heat utilization device (7) comprises two groups of absorption heat pump devices, which are divided into a primary heat pump (30) and a secondary heat pump (31), and an intermediate heat medium circulation loop (32) is provided between the primary heat pump (30) and the secondary heat pump (31).

5. A desorption tower bottom liquid waste heat utilization system based on the absorption heat pump principle according to claim 4, characterized in that: The first material pipe (10) is provided with a first branch pipe (33) and a second branch pipe (34); the first branch pipe (33) is connected to the absorber (15) or the condenser (17) of the primary heat pump (30); the second branch pipe (34) is connected to the secondary heat pump (31) and passes through the absorber (15) and the condenser (17) in sequence; the two branch pipes converge and are connected to the second material pipe (11); and the third material pipe (13) is connected to the evaporator (18) of the primary heat pump (30).

6. A desorption tower bottom liquid waste heat utilization system based on the absorption heat pump principle according to claim 5, characterized in that: The intermediate heat medium circulation loop (32) is connected to the primary heat pump (30) and to an absorber (15) or a condenser (17) different from the first branch pipe (33) through the H1 pipeline (35); the intermediate heat medium circulation loop (32) flows out of the primary heat pump (30) through the H2 pipeline (36) and is connected to the evaporator (18) of the secondary heat pump (31), and flows back from the evaporator (18) of the secondary heat pump (31) to the H1 pipeline (35).

7. A system for utilizing waste heat from desorption tower bottom liquid based on the absorption heat pump principle according to claim 6, characterized in that: The H1 pipeline (35) or the H2 pipeline (36) is provided with a heat medium circulation pump (37).

8. The system for utilizing waste heat of desorption tower bottom liquid based on the absorption heat pump principle according to claim 1, characterized in that: A cross-line pipe (38) is provided between the third material pipe (13) and the fourth material pipe (14), and a cross-line regulating valve (39) is provided on the cross-line pipe (38).

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