Multi-stage cascade compression absorption heat pump system and working method

Abstract

The present invention provides a multi-stage cascade compression absorption heat pump system and operating method, comprising a cascade compression heat pump sub-circulation system and an absorption heat pump sub-circulation system. The cascade compression heat pump sub-circulation system includes a low-temperature stage compressor, a cascade heat exchanger, a first throttle valve, a compression cycle evaporator, a medium-temperature stage compressor, a first compression cycle condenser, a second compression cycle condenser, and a second throttle valve. The absorption heat pump sub-circulation system includes an absorber, a generator, an absorption cycle condenser, an absorption cycle evaporator, a solution pump, a refrigerant pump, a third throttle valve, and a solution heat recovery device. By combining the cascade compression heat pump sub-circulation system and the absorption heat pump sub-circulation system, a solution is achieved that improves the temperature rise capability of the cascade compression heat pump and the efficiency of the absorption heat pump, and helps improve waste heat recovery efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of energy recovery, and in particular to a multi-stage cascade compression absorption heat pump system and a working method. Background Art

[0002] Energy and environmental issues are two major challenges to sustainable development in today's society. In the industrial sector, the extensive use of energy in production processes exacerbates the imbalance between energy supply and demand. The direct release of industrial waste heat into the environment results in a significant amount of low-grade thermal energy being wasted. To reduce waste heat, heat pump technology can be used to upgrade heat from industrial waste heat or the environment, outputting high-quality thermal energy for reuse. This not only efficiently utilizes energy, but also reduces waste heat, resulting in significant economic benefits.

[0003] Heat pump technology can utilize low-quality heat input to produce high-quality heat output. Typical heat pump technologies can be categorized as compression heat pumps and absorption heat pumps. Compression heat pumps are driven by electrical or mechanical energy to increase the heat temperature. Absorption heat pumps can be categorized as either Type I or Type II absorption heat pumps. Type I absorption heat pumps utilize high-temperature input to generate medium-temperature heat output, with the output heat output having a higher power than the input heat. Type II absorption heat pumps utilize medium-temperature heat input to generate high-temperature heat output, with the output heat output having a lower power than the input heat.

[0004] A Chinese patent application, publication number CN110030769B, discloses a medium- and low-temperature heat energy supply system based on a warming absorption-compression heat exchange system. The system comprises a medium- and low-temperature heat source, a heat source station, a primary network, a thermal power station, and a secondary network, all connected in sequence. The heat source station is a first water-to-water heat exchanger, and the thermal power station is a compression heat exchanger unit or a second water-to-water heat exchanger. The medium- and low-temperature heat source can be medium- and low-temperature industrial waste heat, medium- and deep-seated geothermal heat, or medium- and low-temperature circulating water from a solar collector. This system utilizes heat exchangers configured at the medium- and low-temperature heat source station based on the characteristics of the medium- and low-temperature heat carriers, and compression heat exchangers configured at the thermal power station based on the characteristics of the heat users. This system can significantly reduce the return water temperature of the primary heating network and increase the primary supply water temperature.

[0005] Both compression heat pumps and absorption heat pumps have a variety of different cycles, such as the cascade compression cycle, double-effect absorption cycle, and two-stage absorption cycle. However, both compression heat pumps and absorption heat pumps have their own problems: although compression heat pumps have high efficiency, their temperature-raising capacity is limited, and they require high-quality electricity, making them suitable for medium and low-temperature ranges. Absorption heat pumps consume low-quality thermal energy and can achieve higher output temperatures, but they require higher input temperatures and have lower energy efficiency, making them more suitable for high-temperature ranges. The two heat pump technologies have different characteristics in terms of efficiency, adaptability, and energy consumption types. Effectively combining the two heat pump technologies and achieving complementary advantages is an effective way to address the shortcomings of the two heat pump technologies. Summary of the Invention

[0006] In view of the defects in the prior art, the purpose of the present invention is to provide a multi-stage cascade compression absorption heat pump system and working method.

[0007] According to the present invention, a multi-stage cascade compression absorption heat pump system and working method are provided, comprising: a cascade compression heat pump sub-circulation system: comprising a low-temperature stage compressor, a cascade heat exchanger, a compression cycle evaporator, a medium-temperature stage compressor and a compression cycle condenser; the outlet of the low-temperature stage compressor is connected to the inlet of the compression cycle evaporator through the cascade heat exchanger, and the outlet of the compression cycle evaporator is connected to the inlet of the low-temperature stage compressor; the outlet of the medium-temperature stage compressor is connected to multiple compression cycle condensers in sequence, and the outlet of the compression cycle condenser is connected to the inlet of the medium-temperature stage compressor through the cascade heat exchanger; an absorption heat pump sub-circulation system: comprising an absorber, an absorber Circulating evaporator, generator, absorption circulation condenser, solution heat recovery device; the outlet of the absorber is connected to the inlet of the generator through the solution heat recovery device, one of the compression circulation condensers is arranged in the generator, the first outlet of the generator is connected to the first inlet of the absorber through the solution heat recovery device, the second outlet of the generator is connected to the inlet of the absorption circulation condenser, the compression circulation evaporator is arranged in the absorption circulation condenser, the outlet of the absorption circulation condenser is connected to the inlet of the absorption circulation evaporator, the other compression circulation condenser is arranged in the absorption circulation evaporator, the outlet of the absorption circulation evaporator is connected to the second inlet of the absorber.

[0008] Preferably, the compression cycle condenser includes a first compression cycle condenser and a second compression cycle condenser; the first compression cycle condenser is arranged in the generator, and the second compression cycle condenser is arranged in the absorption cycle evaporator.

[0009] Preferably, the first outlet of the generator is communicated with one end of the solution pump, and the other end of the solution pump is communicated with the first inlet of the absorber through the solution heat recovery device.

[0010] Preferably, the outlet of the absorber is communicated with one end of a third throttle valve through a solution heat recovery device, and the other end of the third throttle valve is communicated with the inlet of the generator.

[0011] Preferably, the outlet of the absorption cycle condenser is communicated with one end of a refrigerant pump, and the other end of the refrigerant pump is communicated with the inlet of the absorption cycle evaporator.

[0012] Preferably, one end of the outlet of the compression cycle evaporator is connected to a second throttle valve, and the other end of the second throttle valve is connected to the inlet of the low-temperature stage compressor.

[0013] Preferably, the outlet of the low-temperature stage compressor is connected to one end of a first throttle valve through a cascade heat exchanger, and the other end of the first throttle valve is connected to a compression cycle evaporator.

[0014] According to the present invention, a working method of a multi-stage cascade compression absorption heat pump system is provided, and the working method includes:

[0015] Working method of cascade compression heat pump sub-circulation system:

[0016] The first refrigerant vapor enters the cascade heat exchanger from the low-temperature stage compressor and is condensed to form a first refrigerant liquid. The first refrigerant liquid enters the compression cycle evaporator from the cascade heat exchanger through the first throttle valve and absorbs heat from the low-grade heat source and / or waste heat and / or heat from the absorption cycle condenser to form a second refrigerant vapor. The second refrigerant vapor is compressed from the compression cycle evaporator by the low-temperature stage compressor to generate the first refrigerant vapor and enter the cascade heat exchanger.

[0017] After the third refrigerant vapor enters the first compression cycle condenser from the intermediate temperature stage compressor, the generator is heated to form a second refrigerant liquid. The second refrigerant liquid enters the second compression cycle condenser from the first compression cycle condenser to be condensed, and the absorption cycle evaporator is heated to form a third refrigerant liquid. The third refrigerant liquid enters the cascade heat exchanger from the second compression cycle condenser through the second throttle valve and absorbs heat from the first refrigerant vapor to form a fourth refrigerant vapor. The fourth refrigerant vapor is compressed in the intermediate temperature stage compressor from the cascade heat exchanger to generate a third refrigerant vapor, and then enters the first compression cycle condenser.

[0018] Working method of absorption heat pump sub-circulation system:

[0019] The solution of the generator enters the absorber through the solution pump and the solution heat recovery device. After the solution absorbs the sixth refrigerant vapor from the absorption cycle evaporator in the absorber, it releases heat output. The solution returns to the generator from the absorber through the solution heat recovery device and the third throttle valve. The solution returned to the generator is the recovered solution. The recovered solution is heated in the first compression cycle condenser in the generator to produce the fifth refrigerant vapor. The remaining solution then enters the solution pump. After the fifth refrigerant vapor enters the absorption cycle condenser from the generator and is condensed, the compression cycle evaporator is heated and the fourth refrigerant liquid is formed. The fourth refrigerant liquid enters the absorption cycle evaporator from the absorption cycle condenser through the refrigerant pump. After the fourth refrigerant liquid enters the absorption cycle evaporator, it absorbs heat from the second compression cycle condenser to form the sixth refrigerant vapor and enters the absorber.

[0020] Preferably, when waste heat is generated, the waste heat is transferred to the compression cycle evaporator.

[0021] Preferably, the first refrigerant liquid exchanges heat with the third refrigerant liquid in the cascade heat exchanger to generate the first refrigerant vapor; and the third refrigerant liquid exchanges heat with the first refrigerant liquid in the cascade heat exchanger to generate the fourth refrigerant vapor.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The present invention realizes a solution that can improve the temperature rise capability of the cascade compression heat pump and the efficiency of the absorption heat pump through the cascade compression heat pump sub-circulation system and the absorption heat pump sub-circulation system, and helps to improve the waste heat recovery efficiency.

[0024] 2. In the present invention, the heat released by the absorption cycle condenser of the absorption heat pump sub-circulation system can be input into the compression cycle evaporator of the cascade compression heat pump sub-circulation system, thereby reducing the input of waste heat and improving the overall thermal efficiency, which helps to increase the output temperature of the working mode.

[0025] 3. The present invention inputs waste heat into the compression cycle evaporator of the cascade compression heat pump sub-circulation system, and after the temperature of the cascade compression heat pump sub-circulation system is increased, the waste heat is output from the compression cycle condenser of the cascade compression heat pump sub-circulation system to the absorption cycle evaporator and generator. The heat is further increased in temperature by the absorption heat pump sub-circulation system and finally output from the absorber of the absorption heat pump sub-circulation system, which helps to improve the waste heat recovery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0027] Figure 1This is a schematic diagram of the overall structure of a multi-stage cascade compression absorption heat pump system mainly embodied in the present invention.

[0028] As shown in the figure:

[0029] Absorber 1 Medium temperature compressor 11

[0030] Absorption cycle evaporator 2 First compression cycle condenser 12

[0031] Generator 3 Second throttle valve 13

[0032] Absorption cycle condenser 4 Second compression cycle condenser 14

[0033] Solution heat recovery device 5 Cascade heat exchanger 15

[0034] Solution pump 6 Low temperature compressor 21

[0035] Third throttle valve 7 First throttle valve 22

[0036] Refrigerant pump 8 Compression cycle evaporator 23 DETAILED DESCRIPTION

[0037] The present invention will be described in detail below with reference to specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those skilled in the art, several changes and improvements can be made without departing from the scope of the present invention. These all fall within the scope of protection of the present invention.

[0038] Example 1

[0039] like Figure 1 As shown, a multi-stage cascade compression absorption heat pump system and working method provided according to the present invention include a cascade compression heat pump sub-circulation system and an absorption heat pump sub-circulation system. The cascade compression heat pump sub-circulation system includes a low-temperature stage compressor 21, a cascade heat exchanger 15, a compression cycle evaporator, a medium-temperature stage compressor 11 and a compression cycle condenser.

[0040] The outlet of the low-temperature stage compressor 21 is connected to the inlet of the compression cycle evaporator through the cascade heat exchanger 15 , and the outlet of the compression cycle evaporator is connected to the inlet of the low-temperature stage compressor 21 .

[0041] The outlet of the medium-temperature stage compressor 11 is connected to a plurality of compression cycle condensers in sequence, and the outlet of the compression cycle condenser is connected to the inlet of the medium-temperature stage compressor 11 through the cascade heat exchanger 15 .

[0042] The absorption heat pump sub-circulation system includes an absorber 1, an absorption circulation evaporator 2, a generator 3, an absorption circulation condenser 4, and a solution heat recovery device 5.

[0043] The outlet of the absorber 1 is connected to the inlet of the generator 3 through the solution heat recovery device 5. One compression cycle condenser is arranged in the generator 3. The first outlet of the generator 3 is connected to the first inlet of the absorber 1 through the solution heat recovery device 5. The second outlet of the generator 3 is connected to the inlet of the absorption cycle condenser 4. The compression cycle evaporator is arranged in the absorption cycle condenser 4. The outlet of the absorption cycle condenser 4 is connected to the inlet of the absorption cycle evaporator 2. Another compression cycle condenser is arranged in the absorption cycle evaporator 2. The outlet of the absorption cycle evaporator 2 is connected to the second inlet of the absorber 1.

[0044] Specifically, the compression cycle condenser includes a first compression cycle condenser 12 and a second compression cycle condenser 14 . The first compression cycle condenser 12 is disposed in the generator 3 , and the second compression cycle condenser 14 is disposed in the absorption cycle evaporator 2 .

[0045] The first outlet of the generator 3 is communicated with one end of the solution pump 6 , and the other end of the solution pump 6 is communicated with the first inlet of the absorber 1 through the solution heat recovery device 5 .

[0046] The outlet of the absorber 1 is connected to one end of the third throttle valve 7 through the solution heat recovery device 5, and the other end of the third throttle valve 7 is connected to the inlet of the generator 3.

[0047] The outlet of the absorption cycle condenser 4 is communicated with one end of the refrigerant pump 8 , and the other end of the refrigerant pump 8 is communicated with the inlet of the absorption cycle evaporator 2 .

[0048] One end of the second throttle valve 13 is connected to the outlet of the compression cycle evaporator, and the other end of the second throttle valve 13 is connected to the inlet of the low-temperature stage compressor 21.

[0049] The outlet of the low-temperature stage compressor 21 is communicated with one end of the first throttle valve 22 through the cascade heat exchanger 15, and the other end of the first throttle valve 22 is communicated with the compression cycle evaporator.

[0050] The present invention also provides a working method of a multi-stage cascade compression absorption heat pump system. Based on the above-mentioned multi-stage cascade compression absorption heat pump system, the working method includes a working method of a cascade compression heat pump sub-circulation system and a working method of an absorption heat pump sub-circulation system.

[0051] Working method of cascade compression heat pump sub-circulation system:

[0052] The first refrigerant vapor enters the cascade heat exchanger 15 from the low-temperature stage compressor 21 and is condensed to form a first refrigerant liquid. The first refrigerant liquid enters the compression cycle evaporator from the cascade heat exchanger 15 through the first throttle valve 22, and absorbs heat from the low-grade heat source and / or waste heat and / or heat from the absorption cycle condenser 4 to form a second refrigerant vapor. The second refrigerant vapor is compressed from the compression cycle evaporator through the low-temperature stage compressor 21 to generate the first refrigerant vapor and enter the cascade heat exchanger 15.

[0053] After the third refrigerant vapor enters the first compression cycle condenser 12 from the medium-temperature compressor 11, the generator 3 is heated and a second refrigerant liquid is formed. The second refrigerant liquid enters the second compression cycle condenser 14 from the first compression cycle condenser 12 to be condensed, and the absorption cycle evaporator 2 is heated to form a third refrigerant liquid. The third refrigerant liquid enters the cascade heat exchanger 15 from the second compression cycle condenser 14 through the second throttle valve 13, and absorbs heat from the first refrigerant vapor to form a fourth refrigerant vapor. After the fourth refrigerant vapor is compressed from the cascade heat exchanger 15 through the medium-temperature compressor 11, the third refrigerant vapor is generated and enters the first compression cycle condenser 12.

[0054] Working method of absorption heat pump sub-circulation system:

[0055] The solution of the generator 3 enters the absorber 1 through the solution pump 6 and the solution heat recovery device 5. After the absorber 1 absorbs the sixth refrigerant vapor from the absorption cycle evaporator 2, the solution releases heat output. The solution returns to the generator 3 from the absorber 1 through the solution heat recovery device 5 and the third throttle valve 7. The solution returned to the generator 3 is the recovered solution. The recovered solution is heated in the generator 3 by the first compression cycle condenser 12 to generate the fifth refrigerant vapor. The remaining solution then enters the solution pump 6. After the fifth refrigerant vapor enters the absorption cycle condenser 4 from the generator 3 and is condensed, the compression cycle evaporator is heated and a fourth refrigerant liquid is formed. The fourth refrigerant liquid enters the absorption cycle evaporator 2 from the absorption cycle condenser 4 through the refrigerant pump 8. After the fourth refrigerant liquid enters the absorption cycle evaporator 2, it absorbs heat from the second compression cycle condenser 14 to form the sixth refrigerant vapor and enters the absorber 1.

[0056] Specifically, when waste heat is generated, it is transferred to the compression cycle evaporator. The first refrigerant liquid exchanges heat with the third refrigerant liquid in the cascade heat exchanger 15 to produce a first refrigerant vapor. The third refrigerant liquid also exchanges heat with the first refrigerant liquid in the cascade heat exchanger 15 to produce a fourth refrigerant vapor.

[0057] More specifically, when operating in working mode, waste heat is input into the compression cycle evaporator of the cascade compression heat pump sub-circulation system. After undergoing a temperature increase within the cascade compression heat pump sub-circulation system, the heat is output from the compression cycle condenser of the cascade compression heat pump sub-circulation system to the absorption cycle evaporator 2 and generator 3. The heat is further heated within the absorption heat pump sub-circulation system before ultimately being output from the absorber 1 of the absorption heat pump sub-circulation system. Furthermore, heat released by the absorption cycle condenser 4 of the absorption heat pump sub-circulation system can be input into the compression cycle evaporator of the cascade compression heat pump sub-circulation system, thereby reducing waste heat input and improving overall thermal efficiency. The working mode features a relatively high output temperature.

[0058] Specifically, the heat output of the cascade compression heat pump sub-circulation system can enter the absorption circulation evaporator 2 and generator 3 of the absorption heat pump sub-circulation system simultaneously, or can enter the absorption circulation generator 3 and evaporator of the absorption heat pump sub-circulation system in sequence.

[0059] One feasible implementation involves using a lithium bromide aqueous solution as the working fluid pair for the absorption heat pump sub-circulation system, with the heat output of the cascade compression heat pump sub-circulation system sequentially heating the evaporation and generation processes of the absorption heat pump sub-circulation system to reduce the risk of crystallization in the system. When using an ammonia aqueous solution as the working fluid pair for the absorption heat pump sub-circulation, the condensation heat of the cascade compression heat pump sub-circulation system sequentially heating the generation and evaporation processes of the absorption heat pump sub-circulation system to reduce system pressure, enhance system safety, and reduce power consumption of the solution pump 6 and the refrigerant pump 8.

[0060] There are multiple heat exchange modes when the compression cycle condenser outputs heat to the generator 3 and the absorption cycle evaporator 2: the first heat exchange mode is that the heat output of the first compression cycle condenser 12 and the second compression cycle condenser 14 is simultaneously input to the absorption cycle evaporator 2 and the generator 3; the second heat exchange mode is that the heat of the compression cycle condenser is sequentially input to the absorption cycle evaporator 2 and the generator 3; the third heat exchange mode is that the heat of the compression cycle condenser is sequentially input to the generator 3 and the absorption cycle evaporator 2. The first heat exchange mode is suitable for situations where the output power of the cascade compression heat pump sub-cycle is high; the second heat exchange mode is suitable for situations where lithium bromide aqueous solution is used as the working fluid of the absorption heat pump sub-cycle, and has the characteristic of low crystallization risk; the third heat exchange mode is suitable for situations where ammonia aqueous solution is used as the working fluid of the absorption heat pump sub-cycle, and has the characteristic of reducing system pressure, solution pump 6 power consumption, and refrigerant pump 8 power consumption.

[0061] Example 2

[0062] Based on Example 1, according to a multi-stage cascade compression absorption heat pump system and operating method provided by the present invention, the main internal heat exchange of the circulation system operating in the working mode is as follows: the first compression cycle condenser 12 exchanges heat with the generator 3, the second compression cycle condenser 14 exchanges heat with the absorption cycle evaporator 2, the absorption cycle condenser 4 exchanges heat with the compression cycle evaporator 23, and the solution entering the absorber 1 from the solution pump 6 and the solution entering the third throttle valve 7 from the absorber exchange heat in the solution heat recovery device 5. The external heat exchange of the circulation system is as follows: waste heat is input to the compression cycle evaporator 23, and the absorber 1 outputs heat externally.

[0063] When operating in working mode, the working fluid flow inside the cascade compression heat pump sub-circulation system is as follows: the low-temperature refrigerant vapor enters the cascade heat exchanger 15 from the low-temperature compressor 21 and condenses into a low-temperature refrigerant liquid and releases heat to the medium-temperature refrigerant liquid on the other side of the cascade heat exchanger 15. The low-temperature refrigerant liquid enters the first throttle valve 22 to reduce the pressure and then enters the compression cycle evaporator 23 to absorb the waste heat and the heat from the absorption cycle condenser 4 and then evaporates into a low-temperature refrigerant vapor. The low-temperature refrigerant vapor enters the low-temperature compressor 21, is compressed and pressurized, and then enters the cascade heat exchanger 15 again.

[0064] The medium-temperature refrigerant vapor enters the first compression cycle condenser 12 from the medium-temperature compressor 11, condenses and releases heat to the generator 3, and then enters the second compression cycle condenser 14 to continue condensing into a medium-temperature refrigerant liquid and releases heat to the absorption cycle evaporator 2. The medium-temperature refrigerant liquid enters the second throttle valve 13 to reduce the pressure and then enters the cascade heat exchanger 15, absorbs heat from the low-temperature refrigerant vapor and evaporates into a medium-temperature refrigerant vapor. The medium-temperature refrigerant vapor enters the medium-temperature compressor 11, is compressed and pressurized, and then enters the first compression cycle condenser 12 again.

[0065] When operating in working mode, the working fluid flow within the absorption heat pump sub-cycle system is as follows: the solution in generator 3 passes through solution pump 6 and solution heat exchanger 5 and enters absorber 1. The solution in absorber 1 absorbs refrigerant vapor from absorption cycle evaporator 2, releasing heat and returning to generator 3 through solution heat exchanger 5 and third throttle valve 7. The solution returned to generator 3 is heated by first compression cycle condenser 12 to produce refrigerant vapor, which then enters solution pump 6 again. The refrigerant vapor generated in this process enters absorption cycle condenser 4. The refrigerant vapor in absorption cycle condenser 4 condenses into refrigerant liquid and releases heat to compression cycle evaporator 23. The refrigerant liquid in absorption cycle condenser 4 passes through refrigerant pump 8 and enters absorption cycle evaporator 2. The refrigerant liquid in absorption cycle evaporator 2 is heated by second compression cycle condenser 14, evaporating into refrigerant vapor and entering absorber 1. The refrigerant used in the absorption heat pump sub-cycle may or may not be one of the refrigerants used in the cascade compression heat pump sub-cycle.

[0066] When running in working mode, there are three connection modes between the medium temperature compressor 11 and the first compression cycle condenser 12 and the second compression cycle condenser 14. Figure 1 In the connection method shown, the outlet of the intermediate-temperature compressor 11 is first connected to the first compression cycle condenser 12 for heat exchange with the generator 3, and then connected to the second compression cycle condenser 14 for heat exchange with the absorption cycle evaporator 2. In addition, the outlet of the intermediate-temperature compressor 11 can be first connected to the second compression cycle condenser 14 for heat exchange with the absorption cycle evaporator 2, and then connected to the first compression cycle condenser 12 for heat exchange with the generator 3; or the outlet of the intermediate-temperature compressor 11 can be connected to both the first compression cycle condenser 12 for heat exchange with the generator 3 and the second compression cycle condenser 14 for heat exchange with the absorption cycle evaporator 2.

[0067] In the description of this application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application.

[0068] The above describes specific embodiments of the present invention. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. The embodiments of this application and the features in the embodiments may be combined with each other in any manner unless there is a conflict.

Claims

1. A multi-stage cascade compression absorption heat pump system, characterized in that: include: The cascade compression heat pump sub-circulation system comprises a low-temperature stage compressor (21), a cascade heat exchanger (15), a compression cycle evaporator (23), a medium-temperature stage compressor (11), and a compression cycle condenser; The outlet of the low-temperature stage compressor (21) is connected to the inlet of the compression cycle evaporator (23) through the cascade heat exchanger (15), and the outlet of the compression cycle evaporator (23) is connected to the inlet of the low-temperature stage compressor (21); The outlet of the medium-temperature compressor (11) is sequentially connected to a plurality of compression cycle condensers, and the outlet of the compression cycle condenser is connected to the inlet of the medium-temperature compressor (11) through the cascade heat exchanger (15); Absorption heat pump subcirculation system: comprising an absorber (1), an absorption circulation evaporator (2), a generator (3), an absorption circulation condenser (4), and a solution heat recovery device (5); The outlet of the absorber (1) is connected to the inlet of the generator (3) through the solution heat recovery device (5), one of the compression cycle condensers is arranged in the generator (3), the first outlet of the generator (3) is connected to the first inlet of the absorber (1) through the solution heat recovery device (5), the second outlet of the generator (3) is connected to the inlet of the absorption cycle condenser (4), the compression cycle evaporator (23) is arranged in the absorption cycle condenser (4), the outlet of the absorption cycle condenser (4) is connected to the inlet of the absorption cycle evaporator (2), and the other compression cycle condenser is arranged in the absorption cycle evaporator (2), and the outlet of the absorption cycle evaporator (2) is connected to the second inlet of the absorber (1).

2. The multi-stage cascade compression absorption heat pump system according to claim 1, characterized in that: The compression cycle condenser includes a first compression cycle condenser (12) and a second compression cycle condenser (14); The first compression cycle condenser (12) is arranged in the generator (3), and the second compression cycle condenser (14) is arranged in the absorption cycle evaporator (2).

3. The multi-stage cascade compression absorption heat pump system method according to claim 1, characterized in that: The first outlet of the generator (3) is communicated with one end of the solution pump (6), and the other end of the solution pump (6) is communicated with the first inlet of the absorber (1) through the solution heat recovery device (5).

4. The multi-stage cascade compression absorption heat pump system according to claim 1, characterized in that: The outlet of the absorber (1) is connected to one end of the third throttle valve (7) through the solution heat recovery device (5), and the other end of the third throttle valve (7) is connected to the inlet of the generator (3).

5. The multi-stage cascade compression absorption heat pump system method according to claim 1, characterized in that: The outlet of the absorption cycle condenser (4) is communicated with one end of a refrigerant pump (8), and the other end of the refrigerant pump (8) is communicated with the inlet of the absorption cycle evaporator (2).

6. The multi-stage cascade compression absorption heat pump system according to claim 1, characterized in that: One end of the outlet of the compression cycle evaporator (23) is connected to the second throttle valve (13), and the other end of the second throttle valve (13) is connected to the inlet of the low-temperature stage compressor (21).

7. The multi-stage cascade compression absorption heat pump system according to claim 1, characterized in that: The outlet of the low-temperature compressor (21) is connected to one end of a first throttle valve (22) through a cascade heat exchanger (15), and the other end of the first throttle valve (22) is connected to a compression cycle evaporator (23).

8. A method for operating a multi-stage cascade compression absorption heat pump system, characterized in that: The multi-stage cascade compression absorption heat pump system according to any one of claims 1 to 7 is used, and the working method includes: Working method of cascade compression heat pump sub-circulation system: The first refrigerant vapor enters the cascade heat exchanger (15) from the low-temperature stage compressor (21) and is condensed to form a first refrigerant liquid. The first refrigerant liquid enters the compression cycle evaporator (23) from the cascade heat exchanger (15) through the first throttle valve (22) and absorbs heat from a low-grade heat source and / or waste heat and / or heat from the absorption cycle condenser (4) to form a second refrigerant vapor. The second refrigerant vapor is compressed from the compression cycle evaporator (23) by the low-temperature stage compressor (21) to generate the first refrigerant vapor and enter the cascade heat exchanger (15). After the third refrigerant vapor enters the first compression cycle condenser (12) from the intermediate temperature stage compressor (11), the generator (3) is heated to form a second refrigerant liquid. The second refrigerant liquid enters the second compression cycle condenser (14) from the first compression cycle condenser (12) to be condensed, and the absorption cycle evaporator (2) is heated to form a third refrigerant liquid. The third refrigerant liquid enters the cascade heat exchanger (15) from the second compression cycle condenser (14) through the second throttle valve (13) and absorbs heat from the first refrigerant vapor to form a fourth refrigerant vapor. The fourth refrigerant vapor is compressed in the intermediate temperature stage compressor (11) from the cascade heat exchanger (15) to generate a third refrigerant vapor, and enters the first compression cycle condenser (12). Working method of absorption heat pump sub-circulation system: The solution of the generator (3) enters the absorber (1) through the solution pump (6) and the solution heat recovery device (5). After the solution absorbs the sixth refrigerant vapor from the absorption cycle evaporator (2) in the absorber (1), it releases heat output. The solution returns to the generator (3) from the absorber (1) through the solution heat recovery device (5) and the third throttle valve (7). The solution returned to the generator (3) is the recovered solution. The recovered solution is heated in the first compression cycle condenser (12) in the generator (3) to generate the fifth refrigerant vapor. The remaining solution then enters the solution pump (6). The fifth refrigerant vapor enters the absorption cycle condenser (4) from the generator (3) and is condensed. The compression cycle evaporator (23) is heated and forms the fourth refrigerant liquid. The fourth refrigerant liquid enters the absorption cycle evaporator (2) from the absorption cycle condenser (4) through the refrigerant pump (8). After entering the absorption cycle evaporator (2), the fourth refrigerant liquid absorbs heat from the second compression cycle condenser (14) to form the sixth refrigerant vapor, which then enters the absorber (1).

9. The operating method of the multi-stage cascade compression absorption heat pump system according to claim 8, characterized in that: When waste heat is generated, the waste heat is transferred to the compression cycle evaporator (23).

10. The operating method of the multi-stage cascade compression absorption heat pump system according to claim 8, characterized in that: The first refrigerant liquid exchanges heat with the third refrigerant liquid in the cascade heat exchanger (15) to generate a first refrigerant vapor; The third refrigerant liquid exchanges heat with the first refrigerant liquid in the cascade heat exchanger (15) to generate a fourth refrigerant vapor.

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