A high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system

Abstract

The present invention discloses a high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system, including a high-temperature heat pump system, a supercritical carbon dioxide power generation system, and a high-temperature energy storage system. The high-temperature heat pump system includes a compressor, a high-temperature radiator, a regenerator A, an expander A, an expander B, a motor, a regenerator B, and a low-temperature absorber A; the working fluid enters the high-temperature side of the high-temperature radiator through the compressor, and a part of the working fluid flowing out of the high-temperature side of the high-temperature radiator flows through the high-temperature side of the regenerator A, the expander A, the low-temperature side of the low-temperature absorber A, and the low-temperature side of the regenerator A in sequence and returns to the compressor; the other part of the working fluid flows through the high-temperature side of the regenerator B, the expander B, and the low-temperature side of the regenerator B in sequence and returns to the compressor. The present invention stores the electric energy of abandoned light and abandoned wind in the form of heat using a high-temperature heat pump system, generates electricity through a supercritical carbon dioxide power generation system, and solves the problem of power supply.

Description

Technical Field

[0001] The present invention belongs to the field of energy technology, and in particular relates to a high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system. Background Art

[0002] In the context of carbon peak and carbon neutrality, it is necessary to build a new power system with new energy as the main body. The unstable and uncontrollable characteristics of new energy (wind power, photovoltaic) power generation will affect the installed capacity of new energy. Therefore, it is necessary to equip it with an energy storage system to further increase the installed capacity of new energy.

[0003] The current mainstream energy storage technology is pumped storage, which has the advantages of long life (more than 50 years) and high charging and discharging efficiency (75%-77%), and is currently the most mainstream energy storage technology. However, pumped storage has defects such as long construction period, high initial investment, and geographical restrictions, which limit its flexible application.

[0004] Among the current new energy storage technologies, the electrochemical energy storage that occupies the mainstream position has defects such as high cost, low safety, and short life cycle. Most of them are small-scale, short-time energy storage power stations. The unit energy storage density of compressed air energy storage is low, and the cost of using ground pressure storage tanks is high. The use of underground salt caverns and abandoned mines can reduce investment costs, but it also has defects such as being restricted by geographical conditions and lacks flexibility. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system. When photovoltaic / wind power is abandoned, the electric energy is stored in the form of heat using the high-temperature heat pump system. When the power grid is short of electricity, the supercritical carbon dioxide power generation system is used to generate electricity and connect to the grid, thus solving the problem of electricity supply.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system, comprising a high-temperature heat pump system, a supercritical carbon dioxide power generation system, and a high-temperature energy storage system.

[0008] The high-temperature heat pump system comprises a compressor, a high-temperature radiator, a regenerator A, an expander A, an expander B, a motor, a regenerator B, and a low-temperature heat absorber A, wherein the compressor, the expander A, the expander B and the motor are coaxially arranged;

[0009] The working fluid of the high-temperature heat pump system enters the high-temperature side of the high-temperature radiator through the compressor, and a part of the working fluid flowing out from the high-temperature side of the high-temperature radiator flows through the high-temperature side of the regenerator A, the expander A, the low-temperature side of the low-temperature heat absorber A, and the low-temperature side of the regenerator A in sequence and returns to the compressor; the other part flows through the high-temperature side of the regenerator B, the expander B, and the low-temperature side of the regenerator B in sequence and returns to the compressor;

[0010] The supercritical carbon dioxide power generation system comprises a generator, an expander, a heat exchanger, a regenerator, a precooler, and a main compressor. The expander and the generator are coaxially arranged. After the carbon dioxide working medium performs work in the expander, it passes through the high-temperature side of the regenerator, the high-temperature side of the precooler, the main compressor, the low-temperature side of the regenerator, and the low-temperature side of the heat exchanger in sequence and returns to the expander.

[0011] The high-temperature energy storage system includes a high-temperature tank and a low-temperature tank. The heat storage medium in the high-temperature tank sequentially enters the high-temperature side of the heat exchanger, the low-temperature tank, the high-temperature side of the low-temperature absorber A, the low-temperature side of the high-temperature radiator, and returns to the high-temperature tank.

[0012] It also includes a low-temperature heat storage system, which includes a cold water tank, a hot water tank, and a low-temperature heat absorber B. The cold water in the cold water tank is sequentially returned to the cold water tank through the low-temperature side of the precooler, the hot water tank, and the high-temperature side of the low-temperature heat absorber B;

[0013] In the high-temperature heat pump system, the working fluid flowing out of the expander B passes through the low-temperature side of the low-temperature heat absorber B and then enters the low-temperature side of the regenerator B.

[0014] The precooler is a heat exchanger.

[0015] The regenerator includes a high-temperature regenerator and a low-temperature regenerator connected in sequence, and the supercritical carbon dioxide power generation system also includes a recompressor; after the carbon dioxide working medium performs work in the expander, it passes through the high-temperature side of the high-temperature regenerator and the high-temperature side of the low-temperature regenerator in sequence, and a part of the carbon dioxide working medium passing through the high-temperature side of the low-temperature regenerator enters the low-temperature side of the low-temperature regenerator through the high-temperature side of the precooler and the main compressor, and the other part enters the recompressor, and enters the low-temperature side of the high-temperature regenerator after merging with the carbon dioxide working medium flowing through the low-temperature side of the low-temperature regenerator.

[0016] The precooler includes a first precooler, a second precooler and an intercooler, and the main compressor includes a main compressor low-pressure part and a main compressor high-pressure part.

[0017] A portion of the carbon dioxide working medium passing through the high temperature side of the low temperature regenerator flows through the high temperature side of the first precooler, and the other portion flows through the high temperature side of the second precooler, and then merges with the carbon dioxide working medium flowing through the high temperature side of the first precooler, and then flows through the low pressure part of the main compressor, the high temperature side of the intercooler, the high pressure part of the main compressor, and the low temperature side of the low temperature regenerator in sequence;

[0018] The water in the cold water tank flows through the low temperature side of the second precooler and the hot water tank in sequence.

[0019] The working fluid of the high temperature heat pump system is nitrogen, argon, air or carbon dioxide.

[0020] The heat transfer medium of the high temperature energy storage system is molten salt, particles or PCM.

[0021] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0022] (1) In one embodiment of the present invention, the working fluid passing through the high-temperature heat release device is divided into two paths. One path passes through the expander B and then returns to the compressor. The other path passes through the high-temperature side of the regenerator A and releases heat before entering the expander A to perform work and supply energy to the compressor. The working fluid after performing work in the expander A enters the low-temperature side of the low-temperature heat absorber A to absorb heat. The high-temperature side of the low-temperature heat absorber A uses the residual heat of the medium in the low-temperature tank to heat the working fluid flowing through the low-temperature side of the low-temperature heat absorber A, thereby further reducing the temperature of the medium in the low-temperature tank and increasing the heat of the working fluid absorbed by the medium in the high-temperature heat pump system.

[0023] Therefore, this embodiment uses the residual heat of the medium in the low-temperature tank to heat the low-temperature side of a part of the working fluid in the high-temperature heat pump system, thereby reducing the temperature of the medium entering the low-temperature side of the high-temperature heat emitter. At the same time, after being divided into two paths, each path is designed with an expander (expander B, expander A). The work done by expander B and expander A offsets the power consumption of part of the compressor, thereby improving the COP of the high-temperature heat pump system (increasing heat output under the same power), and further improving the power generation efficiency of the energy storage power generation system of the present invention.

[0024] (2) In another embodiment of the present invention, a low-temperature heat storage system is used to store waste heat from a supercritical carbon dioxide power generation system and supply it to the low-temperature side of a portion of the working fluid in a high-temperature heat pump system for heat absorption, thereby achieving the purpose of efficient energy storage.

[0025] (3) In another embodiment of the present invention, in a supercritical carbon dioxide power generation system, the regenerator is divided into a high-temperature regenerator and a low-temperature regenerator connected in series, and the carbon dioxide working fluid flowing through the low-temperature regenerator is split, with one part passing through a main compressor and the other part passing through a re-compressor, thereby avoiding the carbon dioxide pinch point phenomenon.

[0026] (4) The lower the temperature of carbon dioxide and the greater its density, the lower the power consumption of the compressor. Therefore, in another embodiment of the present invention, the low-pressure part and the high-pressure part of the main compressor in the supercritical carbon dioxide system are separated, and an intercooler is connected in series. The carbon dioxide in the medium and low pressure state is cooled by the intercooler and then compressed into high pressure, thereby reducing the power consumption of the high-pressure part of the main compressor and improving the power generation efficiency.

[0027] (5) The present invention couples the high-temperature heat pump with the supercritical carbon dioxide power generation system through a high-temperature energy storage system. When valley electricity or photovoltaic / wind power is abandoned, the high-temperature energy storage system is used to store the high-temperature heat energy produced by the high-temperature heat pump. During peak electricity consumption, the supercritical carbon dioxide power generation system generates electricity, which has the advantages of being safe and reliable, low cost, and being able to provide rotational inertia to the power grid, and is not subject to geographical restrictions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural diagram of a high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage and power generation system according to an embodiment of the present invention.

[0029] Explanation of the reference numerals: 1-compressor; 2-expander A; 3-motor; 4-expander B; 5-high-temperature radiator; 6-regenerator A; 7-low-temperature absorber A; 8-regenerator B; 9-low-temperature tank; 10-high-temperature tank; 11-expander; 12-generator; 13-heat exchanger; 14-high-temperature regenerator; 15-low-temperature regenerator; 16-recompressor; 17-low-pressure part of the main compressor; 18-intermediate cooler; 19-high-pressure part of the main compressor; 20-first precooler; 21-second precooler; 22-air-cooling island; 23-cold water tank; 24-hot water tank; 25-low-temperature absorber B. DETAILED DESCRIPTION

[0030] The high temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system proposed by the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more clear based on the following description.

[0031] See also Figure 1 A high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system, comprising a high-temperature heat pump system, a supercritical carbon dioxide power generation system, and a high-temperature energy storage system.

[0032] The high temperature heat pump system comprises a compressor 1, a high temperature heat radiator 5, a regenerator A6, an expander A2, an expander B3, a motor 4, a regenerator B8, and a low temperature heat absorber A7. The compressor 1, the expander A2, the expander B3 and the motor 4 are coaxially arranged.

[0033] The working fluid of the high-temperature heat pump system enters the high-temperature side of the high-temperature radiator 5 through the compressor 1. A part of the working fluid flowing out of the high-temperature side of the high-temperature radiator 5 flows through the high-temperature side of the regenerator A6, the expander A2, the low-temperature side of the low-temperature heat absorber A7, and the low-temperature side of the regenerator A6 in sequence and returns to the compressor 1; the other part of the working fluid flows through the high-temperature side of the regenerator B8, the expander B3, and the low-temperature side of the regenerator B8 in sequence and returns to the compressor 1;

[0034] The supercritical carbon dioxide power generation system includes a generator 12, an expander 11, a heat exchanger 13, a regenerator, a precooler, and a main compressor. The expander 11 and the generator 12 are coaxially arranged. After the carbon dioxide working medium performs work in the expander 11, it passes through the high-temperature side of the regenerator, the high-temperature side of the precooler, the main compressor, the low-temperature side of the regenerator, and the low-temperature side of the heat exchanger 13 in sequence and returns to the expander 11.

[0035] The high-temperature energy storage system includes a high-temperature tank 10 and a low-temperature tank 9. The heat storage medium in the high-temperature tank 10 sequentially enters the high-temperature side of the heat exchanger 13, the low-temperature tank 9, the high-temperature side of the low-temperature heat absorber A7, the low-temperature side of the high-temperature heat emitter 5, and returns to the high-temperature tank 10. The heat transfer medium of the high-temperature energy storage system can be molten salt, particles or PCM.

[0036] The low-temperature heat storage system includes a cold water tank 23, a hot water tank 24, and a low-temperature heat absorber B25. The cold water in the cold water tank 23 is sequentially returned to the cold water tank 23 via the low-temperature side of the precooler, the hot water tank 24, and the high-temperature side of the low-temperature heat absorber B25;

[0037] In the high-temperature heat pump system, the working fluid flowing out of the expander B3 passes through the low-temperature side of the low-temperature heat absorber B25 and enters the low-temperature side of the regenerator B8.

[0038] The low-temperature heat storage system is used to store waste heat from the supercritical carbon dioxide power generation system and supply it to the low-temperature side of the high-temperature heat pump system to absorb heat, thereby achieving the purpose of efficient energy storage.

[0039] To avoid the pinch point phenomenon, the regenerator includes a high-temperature regenerator 14 and a low-temperature regenerator 15 which are connected in sequence. The supercritical carbon dioxide power generation system also includes a recompressor 16. After the carbon dioxide working medium does work in the expander 11, it passes through the high-temperature side of the high-temperature regenerator 14 and the high-temperature side of the low-temperature regenerator 15 in sequence. A part of the carbon dioxide working medium passing through the high-temperature side of the low-temperature regenerator 15 enters the low-temperature side of the low-temperature regenerator 15 through the precooler and the main compressor, and the other part of the carbon dioxide working medium enters the recompressor 16, and enters the low-temperature side of the high-temperature regenerator 14 after merging with the carbon dioxide working medium flowing through the low-temperature side of the low-temperature regenerator 15.

[0040] The precooler is a regenerator, one side of which flows through the carbon dioxide working medium and the other side of which flows through cold water, transferring the heat of the carbon dioxide working medium to the cold water. The precooler includes a first precooler 20, a second precooler 21 and an intercooler 18. The main compressor includes a main compressor low-pressure part 17 and a main compressor high-pressure part 19.

[0041] A portion of the carbon dioxide working medium passing through the high temperature side of the low temperature regenerator 15 flows through the high temperature side of the first precooler 20, and the other portion flows through the high temperature side of the second precooler 21, and then merges with the carbon dioxide working medium flowing through the high temperature side of the first precooler 20, and then flows through the low pressure part 17 of the main compressor, the high temperature side of the intercooler 18, the high pressure part 19 of the main compressor, and the low temperature side of the low temperature regenerator 15 in sequence, and then merges with the carbon dioxide working medium passing through the recompressor 16, enters the low temperature side of the high temperature regenerator 14, the low temperature side of the heat exchanger 13, and returns to the expander 11 to perform work;

[0042] The cold water in the cold water tank 23 flows through the low-temperature side of the second precooler 21 and the hot water tank 24 in sequence. The low-temperature side of the intermediate heat exchanger 13 and the low-temperature side of the first precooler 20 are connected in parallel and then connected to the air-cooling island 22. Any one or both of the intermediate heat exchanger 13 and the first precooler 20 can also be connected to the cold water tank 23 and the hot water tank 24 like the first precooler 20, and there is no limitation here.

[0043] The working principle of the energy storage power generation system of this embodiment is as follows:

[0044] (1) High-temperature heat pump system: The high-temperature and high-pressure working fluid compressed by compressor 1 enters the high-temperature side of high-temperature radiator 5 and transfers heat to the heat storage medium. The working fluid flowing out of the high-temperature side of high-temperature radiator 5 is in a medium-temperature and high-pressure state. The working fluid flowing out of the high-temperature side of high-temperature radiator 54 is divided into two paths. The first path releases heat through the high-temperature side of regenerator A6 and becomes a low-temperature and high-pressure state. It enters expander A2 to expand and do work to supply energy to compressor 1. The working fluid flowing out of expander A2 is in a low-temperature and low-pressure state. It enters the low-temperature side of low-temperature heat absorber A7 and the low-temperature side of regenerator A6 in turn to absorb heat, and then returns to compressor 1. The working fluid of the second path releases heat through the high-temperature side of regenerator B8 and becomes a low-temperature and high-pressure state. It then enters expander B3 to do work to supply energy to compressor 1. The working fluid flowing out of expander B3 is in a low-temperature and low-pressure state. It enters the low-temperature side of low-temperature heat absorber B25 to absorb heat, and then enters the low-temperature side of regenerator B8 to further absorb heat and returns to compressor 1.

[0045] The working fluid of the high temperature heat pump system can be nitrogen, argon, air or carbon dioxide.

[0046] The heat storage medium in the low temperature tank 9 in the high temperature heat storage system enters the high temperature side of the low temperature heat absorber A7 to provide heat for the working medium flowing through the low temperature side of the low temperature heat absorber A7, and then flows back to the low temperature side of the high temperature radiator 5 to absorb heat. First, it can reduce the temperature of the medium flowing back to the inlet of the low temperature side of the high temperature radiator 5, increase the heat absorbed by the medium of the high temperature heat storage system, and reduce the working medium temperature at the outlet of the high temperature side of the high temperature radiator 5; second, it effectively utilizes the residual heat of the medium in the low temperature tank 9; at the same time, after the working medium flowing out of the high temperature radiator 5 is divided into two paths, each path is designed with an expander (expander A2, expander B3), and the work done by expanders A2 and B3 offsets part of the power consumption of compressor 1. Therefore, the heat exchange efficiency of the high temperature heat pump system is effectively increased.

[0047] (2) Supercritical carbon dioxide power generation system: After the carbon dioxide working medium expands and performs work in the expander 11, it enters the high temperature side of the high temperature regenerator 14 and the high temperature side of the low temperature regenerator 15 in turn to release heat and then splits into two streams. One stream enters the high temperature side of the first precooler 20 to further release heat. The second stream enters the second precooler 21 to release heat and then merges with the carbon dioxide working medium of the first stream that has passed through the first precooler 20 and then enters the low pressure part 17 of the main compressor to be compressed into a low temperature, medium and low pressure state. Then, it enters the high temperature side of the intercooler 18 to further release heat and then enters the high pressure part 19 of the main compressor to be compressed into a low temperature, high pressure state and then enters the low temperature regenerator 15 to absorb heat. The third stream of carbon dioxide working medium that flows out of the high temperature side of the low temperature regenerator 15 enters the recompressor 16 to be compressed into high pressure carbon dioxide and then merges with the carbon dioxide working medium that flows out of the low temperature side of the low temperature regenerator 15 and then enters the low temperature side of the high temperature regenerator 14 to absorb heat. Then, it enters the low temperature side of the heat exchanger 13 to further absorb heat from the heat storage medium and then enters the expander 11 to perform work to complete the entire cycle.

[0048] The high-temperature heat pump is coupled with the supercritical carbon dioxide power generation system through a high-temperature energy storage system and a low-temperature heat storage system. When valley electricity or photovoltaic / wind power is abandoned, the high-temperature energy storage system is used to store the high-temperature thermal energy produced by the high-temperature heat pump. During peak electricity consumption, the supercritical carbon dioxide power generation system generates electricity. The low-temperature heat generated during the power generation process is transferred to a part of the flow of working fluid in the high-temperature heat pump system through the water in the low-temperature heat storage system, effectively utilizing the waste heat of the supercritical carbon dioxide power generation system to achieve the purpose of efficient energy storage. The residual heat of the heat storage medium in the low-temperature tank 9 is transferred to another part of the flow of working fluid in the high-temperature heat pump system, reducing the inlet temperature of the low-temperature side of the high-temperature heat release section. At the same time, a group of expanders A2 are added to the high-temperature heat pump system to offset the power consumption of compressor 1, effectively improving the heat exchange efficiency of the high-temperature heat pump system.

[0049] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system, characterized in that: Including high temperature heat pump system, supercritical carbon dioxide power generation system, high temperature energy storage system, The high-temperature heat pump system comprises a compressor, a high-temperature radiator, a regenerator A, an expander A, an expander B, a motor, a regenerator B, and a low-temperature heat absorber A, wherein the compressor, the expander A, the expander B and the motor are coaxially arranged; The working fluid of the high-temperature heat pump system enters the high-temperature side of the high-temperature radiator through the compressor, and a part of the working fluid flowing out from the high-temperature side of the high-temperature radiator flows through the high-temperature side of the regenerator A, the expander A, the low-temperature side of the low-temperature heat absorber A, and the low-temperature side of the regenerator A in sequence and returns to the compressor; Another part of the working fluid flows sequentially through the high temperature side of the regenerator B, the expander B, the low temperature side of the regenerator B and returns to the compressor; The supercritical carbon dioxide power generation system comprises a generator, an expander, a heat exchanger, a regenerator, a precooler, and a main compressor. The expander and the generator are coaxially arranged. After the carbon dioxide working medium performs work in the expander, it passes through the high-temperature side of the regenerator, the high-temperature side of the precooler, the main compressor, the low-temperature side of the regenerator, and the low-temperature side of the heat exchanger in sequence and returns to the expander. The high-temperature energy storage system includes a high-temperature tank and a low-temperature tank. The heat storage medium in the high-temperature tank sequentially enters the high-temperature side of the heat exchanger, the low-temperature tank, the high-temperature side of the low-temperature heat absorber A, the low-temperature side of the high-temperature heat radiator, and returns to the high-temperature tank. The high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system also includes a low-temperature heat storage system, which includes a cold water tank, a hot water tank, and a low-temperature heat absorber B. The cold water in the cold water tank is sequentially returned to the cold water tank through the low-temperature side of the precooler, the hot water tank, and the high-temperature side of the low-temperature heat absorber B; In the high-temperature heat pump system, the working fluid flowing out of the expander B passes through the low-temperature side of the low-temperature heat absorber B and then enters the low-temperature side of the regenerator B.

2. The high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system according to claim 1 is characterized in that: The regenerator includes a high-temperature regenerator and a low-temperature regenerator connected in sequence, and the supercritical carbon dioxide power generation system also includes a recompressor; after the carbon dioxide working medium performs work in the expander, it passes through the high-temperature side of the high-temperature regenerator and the high-temperature side of the low-temperature regenerator in sequence, and a part of the carbon dioxide working medium passing through the high-temperature side of the low-temperature regenerator enters the low-temperature side of the low-temperature regenerator through the high-temperature side of the precooler and the main compressor, and the other part enters the recompressor, and enters the low-temperature side of the high-temperature regenerator after merging with the carbon dioxide working medium flowing through the low-temperature side of the low-temperature regenerator.

3. The high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system according to claim 2 is characterized in that: The precooler includes a first precooler, a second precooler and an intercooler, and the main compressor includes a main compressor low-pressure part and a main compressor high-pressure part. A portion of the carbon dioxide working medium passing through the high temperature side of the low temperature regenerator flows through the high temperature side of the first precooler, and the other portion flows through the high temperature side of the second precooler, and then merges with the carbon dioxide working medium flowing through the high temperature side of the first precooler, and then flows through the low pressure part of the main compressor, the high temperature side of the intercooler, the high pressure part of the main compressor, and the low temperature side of the low temperature regenerator in sequence; The water in the cold water tank flows through the low temperature side of the second precooler and the hot water tank in sequence.

4. The high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system according to any one of claims 1 to 3, characterized in that: The working fluid of the high temperature heat pump system is nitrogen, argon, air or carbon dioxide.

5. The high-temperature heat pump and supercritical carbon dioxide combined cycle energy storage power generation system according to any one of claims 1 to 3, characterized in that: The heat transfer medium of the high temperature energy storage system is molten salt or particles.

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