A supercritical CO2 Brayton cycle power generation system and method with electric thermal energy storage

Abstract

The present invention discloses a supercritical CO2 Brayton cycle power generation system and method with electric heat energy storage, the system includes a supercritical CO2 Brayton cycle system, a CO2 heat pump system and a low-temperature power generation system; the supercritical CO2 Brayton cycle system includes a heat source, a supercritical CO2 turbine, a high-temperature regenerator, a low-temperature regenerator, a precooler, a primary compressor, an intercooler, a secondary compressor and a recompressor; the CO2 heat pump system includes a CO2 heat pump system compressor, a heat storage heat exchanger, a cooler, a main valve, a throttling device, a bypass valve, a cold storage heat exchanger, a cold storage tank and a cold water pump; the low-temperature power generation system includes a low-temperature power generation system turbine, a regenerator, a cooler, a compressor, a heater, a heat storage working fluid pump and a heat storage tank. The system recycles the heat released by the precooler and the intercooler in the supercritical CO2 power generation system, uses the surplus power of the power grid to drive the heat pump to improve the quality of this part of the heat and then stores it, and then releases it to the low-temperature power generation system for power generation when needed, and the efficiency is significantly improved.

Description

Technical Field

[0001] The present invention relates to a power generation system, in particular to a supercritical CO 2 Brayton cycle power generation system and method. Background Art

[0002] Under the background of energy shortage and environmental crisis, people pay more and more attention to improving energy utilization. Among many thermodynamic cycles, supercritical Brayton cycle is the most advantageous cycle. New supercritical working fluids (carbon dioxide, helium and nitrous oxide, etc.) have inherent advantages such as high energy density, high heat transfer efficiency and simple system. They can greatly improve the heat-to-work conversion efficiency, reduce the size of equipment and have high economy.

[0003] On the other hand, with the increase of new energy, especially wind power and solar photovoltaic power generation, the impact of new energy power generation on the power grid has become more and more obvious. In order to solve this problem, energy storage has received more and more attention. The current energy storage systems include battery energy storage, compressed air energy storage, pumped water energy storage, etc. Battery energy storage has the highest efficiency, but the cost is too high. Compressed air energy storage requires the storage of a large amount of compressed air. Generally, caves and other special terrains are selected to store compressed air. Pumped water energy storage requires the construction of reservoirs, which also requires a considerable amount of construction. Electric thermal energy storage is a better way to store energy. Generally, electric thermal energy storage is a combined heat pump cycle and low-temperature power generation cycle. First, the excess electricity is used to drive the heat pump to absorb low-temperature heat from the air or river water. The quality of the heat is improved by the pump's heating and pressurization, and then it is stored. When electricity is needed, the heat is released to the low-temperature power generation cycle device, and the low-temperature power generation cycle device absorbs the heat and generates electricity. The aforementioned supercritical CO 2 When the power generation system is running, the precooler and other equipment need to release a large amount of low-temperature heat to the external environment. This heat is slightly higher than the temperature of the ambient air or water. If the heat is absorbed from this heat source and the quality is improved by a heat pump and then stored, its utilization efficiency will be higher.

[0004] The present invention is aimed at this problem and proposes a supercritical CO 2 Brayton cycle power generation system, supercritical CO 2 The heat released by the precooler and intercooler in the Brayton cycle power generation system is recovered by the heat pump system, and then stored after the quality is improved by the heat pump. When needed, it is used for power generation through the low-temperature power generation system, which improves the energy storage efficiency. Summary of the invention

[0005] In order to overcome the problems existing in the prior art, the present invention aims to improve the utilization efficiency of electric thermal energy storage and proposes a supercritical CO 2 Brayton cycle power generation system and method for converting supercritical CO2 The heat released by the precooler and intercooler in the Brayton cycle power generation system is recovered through the heat pump system, stored after its quality is improved by the heat pump, and then used for power generation through the low-temperature power generation system when needed, thereby improving the energy storage efficiency.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] A supercritical CO with electric thermal energy storage 2 Brayton cycle power generation systems, including supercritical CO 2 Brayton cycle system, CO 2 Heat pump systems and low temperature power generation systems;

[0008] The supercritical CO 2 The Brayton cycle system includes a heat source 1-1, an outlet of the heat source 1-1 and a supercritical CO 2 The inlets of turbines 1 and 2 are connected, and supercritical CO 2 The outlet of turbine 1-2 and supercritical CO 2 The hot side inlets of high temperature regenerators 1-3 are connected, and supercritical CO 2 The hot side outlet of high temperature regenerator 1-3 and supercritical CO 2 The hot side inlets of low temperature regenerators 1-4 are connected, and supercritical CO 2 The hot side outlet of the low temperature regenerator 1-4 is divided into two paths, one of which is connected to the supercritical CO 2 The hot side inlets of precoolers 1-5 are connected, and supercritical CO 2 The hot side outlet of precooler 1-5 and supercritical CO 2 The inlets of the first-stage compressors 1-6 are connected, and the supercritical CO 2 The outlet of the first-stage compressor 1-6 is connected to the supercritical CO 2 The hot side inlets of intercoolers 1-7 are connected, and supercritical CO 2 The hot side outlet of the intercooler 1-7 is connected to the inlet of the supercritical CO2 secondary compressor 1-8, and the outlet of the supercritical CO2 secondary compressor 1-8 is connected to the supercritical CO 2 The cold side inlets of low temperature regenerators 1-4 are connected, and supercritical CO 2 The cold side outlet of the low temperature regenerator 1-4 and the supercritical CO 2 The cold side inlets of high temperature regenerators 1-3 are connected, and supercritical CO 2 Another outlet of the hot side of the low temperature regenerator 1-4 is connected to the supercritical CO 2 The inlets of compressors 1-9 are connected, and supercritical CO 2 The outlet of recompressor 1-9 is connected to supercritical CO 2 The cold side outlets of low temperature regenerators 1-4 are combined with supercritical CO 2The cold side inlets of high temperature regenerators 1-3 are connected, and supercritical CO 2 The cold side outlet of the high temperature regenerator 1-3 is connected to the inlet of the heat source 1-1;

[0009] The CO 2 Heat pump systems include CO 2 Heat pump system compressor 2-1, CO 2 The outlet of heat pump system compressor 2-1 and CO 2 The hot side inlet of the heat storage heat exchanger 2-2 of the heat pump system is connected, CO 2 The hot side outlet of the heat storage heat exchanger 2-2 of the heat pump system and the CO 2 The inlet of the heat pump system cooler 2-3 is connected, CO 2 The outlet of the heat pump system cooler 2-3 is divided into two routes, one of which is connected to the CO 2 The heat pump system main valve 2-4 inlet is connected, CO 2 Heat pump system main valve 2-4 outlet and CO 2 The inlet of the heat pump system throttling device 2-5 is connected, and the other is connected to the CO 2 The inlet of the heat pump system bypass valve 2-6 is connected, CO 2 Heat pump system bypass valve 2-6 outlet and CO 2 The outlet of the heat pump system throttling device 2-5 is combined with the CO 2 The hot side inlets of the heat pump system cold storage heat exchangers 2-7 are connected, CO 2 The hot side outlet of the heat pump system cold storage heat exchanger 2-7 and the CO 2 The inlet of the heat pump system compressor 2-1 is connected, CO 2 The cold side outlet of the heat pump system cold storage heat exchanger 2-7 and the CO 2 The inlets of the heat pump system cold storage tanks 2-8 are connected, CO 2 The outlet of the heat pump system cold storage tank 2-8 is connected to the CO 2 The inlet of the heat pump system cold water pump 2-9 is connected, CO 2 The outlets of the heat pump system cold water pumps 2-9 are connected to the supercritical CO 2 Cold side inlet of precooler 1-5, supercritical CO 2 The cold side inlet of the intercooler 1-7 and the cold side inlet of the low temperature power generation system cooler 3-3 are connected, and the supercritical CO 2 Cold side outlet of precooler 1-5, supercritical CO 2 The cold side outlet of intercooler 1-7 and the cold side outlet of low temperature power generation system cooler 3-3 are connected to CO 2 The cold side inlet of the heat pump system cold storage heat exchanger 2-7 is connected;

[0010] The low-temperature power generation system comprises a low-temperature power generation system turbine 3-1, the outlet of the low-temperature power generation system turbine 3-1 is connected to the hot side inlet of the low-temperature power generation system regenerator 3-2, the hot side outlet of the low-temperature power generation system regenerator 3-2 is connected to the hot side inlet of the low-temperature power generation system cooler 3-3, the hot side outlet of the low-temperature power generation system cooler 3-3 is connected to the inlet of the low-temperature power generation system compressor 3-4, the outlet of the low-temperature power generation system compressor 3-4 is connected to the cold side inlet of the low-temperature power generation system regenerator 3-2, the cold side outlet of the low-temperature power generation system regenerator 3-2 is connected to the cold side inlet of the low-temperature power generation system heater 3-5, the cold side outlet of the low-temperature power generation system heater 3-5 is connected to the inlet of the low-temperature power generation system turbine 3-1, the hot side outlet of the low-temperature power generation system heater 3-5 is connected to the inlet of the low-temperature power generation system heat storage working fluid pump 3-6, and the outlet of the low-temperature power generation system heat storage working fluid pump 3-6 is connected to the CO 2 The low temperature side inlet of the heat storage heat exchanger 2-2 of the heat pump system is connected, CO 2 The low temperature side outlet of the heat storage heat exchanger 2-2 of the heat pump system is connected to the inlet of the low temperature power generation system heat storage tank 3-7, and the outlet of the low temperature power generation system heat storage tank 3-7 is connected to the hot side inlet of the low temperature power generation system heater 3-5.

[0011] The supercritical CO 2 The primary compressor 1-6 and the supercritical CO2 secondary compressor 1-8 are coaxial and have the same rotation speed.

[0012] The CO 2 The inlet pressure of the heat pump system compressor 2-1 is 3MPa~4MPa, and the outlet pressure is 24MPa~30MPa.

[0013] The working method of the supercritical CO2 Brayton cycle power generation system with electric thermal energy storage, the supercritical CO 2 The Brayton cycle system is the main power generation system. During normal power generation, high-pressure CO 2 First, it absorbs heat in the heat source 1-1 and becomes a high-temperature and high-pressure working fluid, which enters the supercritical CO 2 Turbine 1-2 then generates electricity and becomes a low-pressure working fluid, which first enters the supercritical CO 2 The hot side of high temperature regenerator 1-3 then enters supercritical CO 2 The heat is released from the hot side of the low temperature regenerator 1-4, and then CO 2 The working fluid is divided into two paths, one of which enters the supercritical CO 2 The hot side of the precooler 1-5 continues to release heat, and then the low-temperature and low-pressure working fluid enters the supercritical CO 2 The first stage compressor 1-6 boosts the pressure and then enters the supercritical CO 2 Intercooler 1-7 releases heat on the hot side and then enters supercritical CO 2The secondary compressor 1-8 continues to increase the pressure, and the pressurized working fluid enters the supercritical CO 2 The low temperature regenerator 1-4 absorbs heat on the cold side, from supercritical CO 2 The other working fluid diverted from the hot side outlet of the low temperature regenerator 1-4 directly enters the supercritical CO 2 The compressor 1-9 is then pressurized and then mixed with supercritical CO 2 The working fluid absorbed by the cold side of the low-temperature regenerator 1-4 merges and enters the supercritical CO 2 The cold side of the high-temperature regenerator 1-3 continues to absorb heat, and finally enters the heat source 1-1 to be heated to a predetermined temperature to complete the entire supercritical CO 2 Brayton cycle;

[0014] When there is no excess electricity in the grid that needs to be stored, CO 2 The main valve 2-4 of the heat pump system is closed, CO 2 The bypass valve 2-6 of the heat pump system is open, and the low-temperature power generation system does not work; at this time, CO 2 The heat pump system only completes supercritical CO 2 Brayton cycle cooling system role, CO 2 Heat pump system compressor 2-1 does not need to convert CO 2 The working fluid pressure is greatly increased, and only the flow resistance needs to be overcome. 2 The heat pump system compressor 2-1 drives the working fluid to flow through the CO 2 The heat pump system heat storage heat exchanger 2-2 then enters the CO 2 The heat pump system cooler 2-3 is cooled, and then the working fluid passes through CO 2 The heat pump system bypasses valve 2-6 and enters the CO 2 The heat pump system cold storage heat exchanger 2-7 hot side, and finally enters the CO 2 The heat pump system compressor 2-1 completes a cooling circuit cycle; CO 2 The cooling water circuit of the heat pump system maintains normal operation, CO 2 The cooling water in the heat pump system cold storage tank 2-8 is CO 2 2 Heat pump system cold water pump 2-9 extracts and drives it into CO 2 Precooler 1-5 cold side, supercritical CO 2 The cooling water from the intercooler 1-7 cold side and the low temperature power generation system cooler 3-3 cold side absorbs the heat from the CO 2 Precooler 1-5 cold side, supercritical CO 2 The cold side of the intercooler 1-7 and the cold side of the low temperature power generation system cooler 3-3 merge and enter the CO 2 The cold side of the heat pump system cold storage heat exchanger 2-7 is cooled and then returns to CO 2 Heat pump system cold storage tank 2-8;

[0015] When there is excess electricity in the grid that needs to be stored, CO 2 The main valve 2-4 of the heat pump system is opened, CO 2 The heat pump system bypass valve 2-6 is closed, and the low-temperature power generation system does not work; at this time, CO 2 The heat pump system not only plays a role in supercritical CO 2 The Brayton cycle system is a cooling system that also stores excess electrical energy as heat; CO 2 Heat pump system compressor 2-1 to increase CO 2 Working fluid pressure, excess electricity passes through CO 2 The work done by the compressor 2-1 of the heat pump system is converted into heat and electricity. The pressurized and heated working fluid flows through the CO 2 The heat pump system heat storage heat exchanger 2-2 releases heat to the heat storage medium on the hot side, and then enters the CO 2 The heat pump system cooler 2-3 is cooled and then passes through CO 2 After the main valve 2-4 of the heat pump system, the CO 2 The heat pump system throttling device 2-5 throttles and cools down, and then CO 2 The heat pump system cold storage heat exchanger 2-7 releases the low-temperature cold energy to the cooling water on the hot side; the low-temperature power generation system heat storage medium pump 3-6 transports the high-temperature heat storage medium to the CO 2 The heat pump system heat storage heat exchanger 2-2 absorbs heat on the low temperature side and then stores it in the low temperature power generation system heat storage tank 3-7;

[0016] When the grid needs more electricity, the low-temperature power generation system starts working, and the supercritical CO 2 Brayton cycle and CO 2 The heat pump system continues to work; the high-temperature medium stored in the low-temperature power generation system heat storage tank 3-7 flows into the hot side of the low-temperature power generation system heater 3-5 to release heat, and then continues to be transferred from the CO2 to the low-temperature power generation system heat storage medium pump 3-6. 2 The heat storage heat exchanger 2-2 of the heat pump system absorbs heat and returns it to the heat storage tank 3-7 of the low-temperature power generation system; the low-temperature power generation working medium is heated on the cold side of the low-temperature power generation system heater 3-5 and enters the low-temperature power generation system turbine 3-1 to perform work. The working medium releases heat on the hot side of the low-temperature power generation system regenerator 3-2, and then enters the low-temperature power generation system cooler 3-3 to continue to be cooled. The cooled medium is pressurized by the low-temperature power generation system compressor 3-4 and enters the low-temperature side of the low-temperature power generation system regenerator 3-2 to absorb heat, and then enters the cold side of the low-temperature power generation system heater 3-5 to continue to be heated, completing the whole cycle.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a supercritical CO2 Brayton cycle power generation system with electric thermal energy storage, which utilizes the heat released by the supercritical CO2 cycle precooler and intercooler. This part of heat is higher than the temperature of the air or river water in the environment. When the superheat pump system is reused after improving its quality, the thermal efficiency of the system can be effectively increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the structure of the system of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0021] like Figure 1 As shown, a supercritical CO with electric thermal energy storage 2 Brayton cycle power generation systems, including supercritical CO 2 Brayton cycle system, CO 2 Heat pump system and low temperature power generation system; supercritical CO 2 The Brayton cycle system includes a heat source 1-1, a supercritical CO 2 Turbine 1-2, supercritical CO 2 High temperature regenerator 1-3, supercritical CO 2 Low temperature regenerator 1-4, supercritical CO 2 Precooler 1-5, supercritical CO 2 First stage compressor 1-6, supercritical CO 2 Intercooler 1-7, supercritical CO 2 Secondary compressors 1-8 and supercritical CO 2 Recompressor 1-9; CO 2 Heat pump systems include CO 2 Heat pump system compressor 2-1, CO 2 Heat pump system heat storage heat exchanger 2-2, CO 2 Heat pump system cooler 2-3, CO 2 Heat pump system main valve 2-4, CO 2 Heat pump system throttling device 2-5, CO 2 Heat pump system bypass valve 2-6, CO 2 Heat pump system cold storage heat exchanger 2-7, CO 2 Heat pump system cold storage tank 2-8 and CO 2 Heat pump system cold water pump 2-9; low temperature power generation system includes low temperature power generation system turbine 3-1, low temperature power generation system regenerator 3-2, low temperature power generation system cooler 3-3, low temperature power generation system compressor 3-4, low temperature power generation system heater 3-5, low temperature power generation system heat storage working fluid pump 3-6, low temperature power generation system heat storage tank 3-7.

[0022] The outlet of the heat source 1-1 is connected to the supercritical CO 2 The inlets of turbines 1 and 2 are connected, and supercritical CO 2 The outlet of turbine 1-2 and supercritical CO 2 The hot side inlets of high temperature regenerators 1-3 are connected, and supercritical CO 2 The hot side outlet of high temperature regenerator 1-3 and supercritical CO 2 The hot side inlets of low temperature regenerators 1-4 are connected, and supercritical CO 2 The hot side outlet of the low temperature regenerator 1-4 is divided into two paths, one of which is connected to the supercritical CO 2 The hot side inlets of precoolers 1-5 are connected, and supercritical CO 2 The hot side outlet of precooler 1-5 and supercritical CO 2 The inlets of the first-stage compressors 1-6 are connected, and the supercritical CO 2 The outlet of the first-stage compressor 1-6 is connected to the supercritical CO 2 The hot side inlets of intercoolers 1-7 are connected, and supercritical CO 2 The hot side outlet of the intercooler 1-7 is connected to the inlet of the supercritical CO2 secondary compressor 1-8, and the outlet of the supercritical CO2 secondary compressor 1-8 is connected to the supercritical CO 2 The cold side inlets of low temperature regenerators 1-4 are connected, and supercritical CO 2 The cold side outlet of the low temperature regenerator 1-4 and the supercritical CO 2 The cold side inlets of high temperature regenerators 1-3 are connected, and supercritical CO 2 Another outlet of the hot side of the low temperature regenerator 1-4 is connected to the supercritical CO 2 The inlets of compressors 1-9 are connected, and supercritical CO 2 The outlet of recompressor 1-9 is connected to supercritical CO 2 The cold side outlets of low temperature regenerators 1-4 are combined with supercritical CO 2 The cold side inlets of high temperature regenerators 1-3 are connected, and supercritical CO 2 The cold side outlet of the high temperature regenerator 1-3 is connected to the inlet of the heat source 1-1.

[0023] The CO 2 The outlet of heat pump system compressor 2-1 and CO 2 The hot side inlet of the heat storage heat exchanger 2-2 of the heat pump system is connected, CO 2 The hot side outlet of the heat storage heat exchanger 2-2 of the heat pump system and the CO 2 The inlet of the heat pump system cooler 2-3 is connected, CO 2 The outlet of the heat pump system cooler 2-3 is divided into two routes, one of which is connected to the CO 2 The heat pump system main valve 2-4 inlet is connected, CO 2Heat pump system main valve 2-4 outlet and CO 2 The inlet of the heat pump system throttling device 2-5 is connected, and the other is connected to the CO 2 The inlet of the heat pump system bypass valve 2-6 is connected, CO 2 Heat pump system bypass valve 2-6 outlet and CO 2 The outlet of the heat pump system throttling device 2-5 is combined with the CO 2 The hot side inlets of the heat pump system cold storage heat exchangers 2-7 are connected, CO 2 The hot side outlet of the heat pump system cold storage heat exchanger 2-7 and the CO 2 The inlet of the heat pump system compressor 2-1 is connected, CO 2 The cold side outlet of the heat pump system cold storage heat exchanger 2-7 and the CO 2 The inlets of the heat pump system cold storage tanks 2-8 are connected, CO 2 The outlet of the heat pump system cold storage tank 2-8 is connected to the CO 2 The inlet of the heat pump system cold water pump 2-9 is connected, CO 2 The outlets of the heat pump system cold water pumps 2-9 are connected to the supercritical CO 2 Cold side inlet of precooler 1-5, supercritical CO 2 The cold side inlet of the intercooler 1-7 and the cold side inlet of the low temperature power generation system cooler 3-3 are connected, and the supercritical CO 2 Cold side outlet of precooler 1-5, supercritical CO 2 The cold side outlet of intercooler 1-7 and the cold side outlet of low temperature power generation system cooler 3-3 are connected to CO 2 The cold side inlets of the heat pump system cold storage heat exchanger 2-7 are connected.

[0024] The outlet of the low-temperature power generation system turbine 3-1 is connected to the hot side inlet of the low-temperature power generation system regenerator 3-2, the hot side outlet of the low-temperature power generation system regenerator 3-2 is connected to the hot side inlet of the low-temperature power generation system cooler 3-3, the hot side outlet of the low-temperature power generation system cooler 3-3 is connected to the inlet of the low-temperature power generation system compressor 3-4, the outlet of the low-temperature power generation system compressor 3-4 is connected to the cold side inlet of the low-temperature power generation system regenerator 3-2, the cold side outlet of the low-temperature power generation system regenerator 3-2 is connected to the cold side inlet of the low-temperature power generation system heater 3-5, the cold side outlet of the low-temperature power generation system heater 3-5 is connected to the inlet of the low-temperature power generation system turbine 3-1, the hot side outlet of the low-temperature power generation system heater 3-5 is connected to the inlet of the low-temperature power generation system heat storage working fluid pump 3-6, and the outlet of the low-temperature power generation system heat storage working fluid pump 3-6 is connected to the CO 2 The low temperature side inlet of the heat storage heat exchanger 2-2 of the heat pump system is connected, CO 2The low temperature side outlet of the heat storage heat exchanger 2-2 of the heat pump system is connected to the inlet of the low temperature power generation system heat storage tank 3-7, and the outlet of the low temperature power generation system heat storage tank 3-7 is connected to the hot side inlet of the low temperature power generation system heater 3-5.

[0025] As a preferred embodiment of the present invention, the supercritical CO 2 The primary compressor 1-6 and the supercritical CO2 secondary compressor 1-8 are coaxial and have the same rotation speed.

[0026] As a preferred embodiment of the present invention, the CO 2 The inlet pressure of the heat pump system compressor 2-1 is 3MPa~4MPa, and the outlet pressure is 24MPa~30MPa. Within this pressure range, the outlet temperature of the CO2 heat pump can reach a higher design temperature (above 300°C). The thermal efficiency of the heat pump system is high, and the cold end temperature can meet the cooling requirements of the supercritical CO2 Brayton cycle power generation system.

[0027] The specific working process of the system of the present invention is:

[0028] Supercritical CO 2 The Brayton cycle system is the main power generation system. During normal power generation, high-pressure CO 2 First, it absorbs heat in the heat source 1-1 and becomes a high-temperature and high-pressure working fluid, which enters the supercritical CO 2 Turbine 1-2 then generates electricity and becomes a low-pressure working fluid, which first enters the supercritical CO 2 The hot side of high temperature regenerator 1-3 then enters supercritical CO 2 The heat is released on the hot side of the warm regenerator 1-4, and then the CO2 working fluid is divided into two paths, one of which enters the supercritical CO 2 The hot side of the precooler 1-5 continues to release heat, and then the low-temperature and low-pressure working fluid enters the supercritical CO 2 The first stage compressor 1-6 boosts the pressure and then enters the supercritical CO 2 Intercooler 1-7 releases heat on the hot side and then enters supercritical CO 2 The secondary compressor 1-8 continues to increase the pressure, and the pressurized working fluid enters the supercritical CO 2 The low temperature regenerator 1-4 absorbs heat on the cold side, from supercritical CO 2 The other working fluid diverted from the hot side outlet of the low temperature regenerator 1-4 directly enters the supercritical CO 2 The compressor 1-9 is then pressurized and then mixed with supercritical CO 2 The working fluid absorbed by the cold side of the low-temperature regenerator 1-4 merges and enters the supercritical CO 2 The cold side of the high-temperature regenerator 1-3 continues to absorb heat, and finally enters the heat source 1-1 to be heated to a predetermined temperature to complete the entire supercritical CO 2 Brayton cycle.

[0029] When there is no excess electricity in the grid that needs to be stored, CO 2 The main valve 2-4 of the heat pump system is closed, CO 2 The heat pump system bypass valve 2-6 is open, and the low-temperature power generation system does not work. At this time, the CO2 heat pump system only completes the supercritical CO 2 Brayton cycle cooling system role, CO 2 Heat pump system compressor 2-1 does not need to convert CO 2 The working fluid pressure is greatly increased, and only the flow resistance needs to be overcome. 2 The heat pump system compressor 2-1 drives the working fluid to flow through the CO 2 The heat pump system heat storage heat exchanger 2-2 then enters the CO 2 The heat pump system cooler 2-3 is cooled, and then the working fluid passes through CO 2 The heat pump system bypasses valve 2-6 and enters the CO 2 The heat pump system cold storage heat exchanger 2-7 hot side, and finally enters the CO 2 The heat pump system compressor 2-1 completes a cooling circuit cycle. 2 The cooling water circuit of the heat pump system maintains normal operation, CO 2 The cooling water in the heat pump system cold storage tank 2-8 is CO 2 The heat pump system cold water pump 2-9 extracts and drives it into the CO 2 Precooler 1-5 cold side, supercritical CO 2 The cooling water from the intercooler 1-7 cold side and the low temperature power generation system cooler 3-3 cold side absorbs the heat from the CO 2 Precooler 1-5 cold side, supercritical CO 2 The cold side of the intercooler 1-7 and the cold side of the low temperature power generation system cooler 3-3 merge and enter the cold side of the CO2 heat pump system cold storage heat exchanger 2-7 to be cooled, and then return to the CO 2 Heat pump system cold storage tank 2-8.

[0030] When there is excess electricity in the grid that needs to be stored, CO 2 The main valve 2-4 of the heat pump system is opened, CO 2 The heat pump system bypass valve 2-6 is closed, and the low-temperature power generation system does not work. 2 The heat pump system not only plays a role in supercritical CO 2 The Brayton cycle system plays the role of a cooling system and also stores excess electrical energy as heat. 2 Heat pump system compressor 2-1 converts CO 2 The working fluid pressure is increased to a higher pressure, and the excess electrical energy is passed through CO 2 The work done by the compressor 2-1 of the heat pump system is converted into heat and electricity. The pressurized and heated working fluid flows through the CO2 The heat pump system heat storage heat exchanger 2-2 releases heat to the heat storage medium on the hot side, and then enters the CO 2 The heat pump system cooler 2-3 is cooled and then passes through CO 2 After the main valve 2-4 of the heat pump system, the CO 2 The heat pump system throttling device 2-5 throttles and cools down, and then CO 2 The heat pump system cold storage heat exchanger 2-7 releases the low-temperature cold energy to the cooling water. The low-temperature power generation system heat storage medium pump 3-6 transports the high-temperature heat storage medium to the CO 2 The heat is absorbed by the low temperature side of the heat storage heat exchanger 2-2 of the heat pump system and then stored in the heat storage tank 3-7 of the low temperature power generation system.

[0031] When there is a need to supplement more electricity in the grid, the low-temperature power generation system starts working, and the supercritical CO2 Brayton cycle system and CO 2 The heat pump system continues to work. The high-temperature medium stored in the low-temperature power generation system heat storage tank 3-7 flows into the hot side of the low-temperature power generation system heater 3-5 to release heat, and then continues to absorb heat from the CO2 heat pump system heat storage heat exchanger 2-2 through the low-temperature power generation system heat storage medium pump 3-6, and returns to the low-temperature power generation system heat storage tank 3-7. After being heated on the cold side of the low-temperature power generation system heater 3-5, the low-temperature power generation medium enters the low-temperature power generation system turbine 3-1 to do work. After doing work, the medium releases heat on the hot side of the low-temperature power generation system regenerator 3-2, and then enters the low-temperature power generation system cooler 3-3 to continue to be cooled. The cooled medium enters the low-temperature side of the low-temperature power generation system regenerator 3-2 through the booster of the low-temperature power generation system compressor 3-4 to absorb heat, and then enters the cold side of the low-temperature power generation system heater 3-5 to continue to be heated, completing the entire cycle.

[0032] but Figure 1 Supercritical CO 2 Other layouts of Brayton cycle power generation systems do not affect the application of the present invention, and the content of the present invention is also applicable to other layouts of supercritical cycle systems. Therefore, the supercritical Brayton cycle system in the present invention is a supercritical Brayton cycle system in a broad sense, and is not limited to the layout shown in the figure. For example, other supercritical Brayton cycle systems may use a multi-stage turbine system, or a turbine system with reheat, or may not use a split recompression system, that is, only one main compressor is used without a recompressor in the figure, and the two regenerators in the figure are combined into one regenerator, etc.

[0033] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A supercritical CO2 Brayton cycle power generation system with electric thermal energy storage, characterized in that: Including supercritical CO2 Brayton cycle system, CO2 heat pump system and low-temperature power generation system; The supercritical CO2 Brayton cycle system comprises a heat source (1-1), wherein the outlet of the heat source (1-1) is connected to the inlet of a supercritical CO2 turbine (1-2), the outlet of the supercritical CO2 turbine (1-2) is connected to the hot side inlet of a supercritical CO2 high temperature regenerator (1-3), the hot side outlet of the supercritical CO2 high temperature regenerator (1-3) is connected to the hot side inlet of a supercritical CO2 low temperature regenerator (1-4), the hot side outlet of the supercritical CO2 low temperature regenerator (1-4) is divided into two paths, one of which is connected to the hot side inlet of a supercritical CO2 precooler (1-5), the hot side outlet of the supercritical CO2 precooler (1-5) is connected to the inlet of a supercritical CO2 primary compressor (1-6), the outlet of the supercritical CO2 primary compressor (1-6) is connected to the hot side inlet of a supercritical CO2 intercooler (1-7), and the supercritical CO2 intermediate cooler (1-8) is connected to the hot side inlet of a supercritical CO2 intermediate cooler (1-9). The hot side outlet of the supercritical CO2 intercooler (1-7) is connected to the inlet of the supercritical CO2 secondary compressor (1-8), the outlet of the supercritical CO2 secondary compressor (1-8) is connected to the cold side inlet of the supercritical CO2 low-temperature regenerator (1-4), the cold side outlet of the supercritical CO2 low-temperature regenerator (1-4) is connected to the cold side inlet of the supercritical CO2 high-temperature regenerator (1-3), the other hot side outlet of the supercritical CO2 low-temperature regenerator (1-4) is connected to the inlet of the supercritical CO2 recompressor (1-9), the outlet of the supercritical CO2 recompressor (1-9) merges with the cold side outlet of the supercritical CO2 low-temperature regenerator (1-4) and is connected to the cold side inlet of the supercritical CO2 high-temperature regenerator (1-3), and the cold side outlet of the supercritical CO2 high-temperature regenerator (1-3) is connected to the inlet of the heat source (1-1); The CO2 heat pump system comprises a CO2 heat pump system compressor (2-1), wherein the outlet of the CO2 heat pump system compressor (2-1) is connected to the hot side inlet of the CO2 heat pump system heat storage heat exchanger (2-2), the hot side outlet of the CO2 heat pump system heat storage heat exchanger (2-2) is connected to the inlet of the CO2 heat pump system cooler (2-3), the outlet of the CO2 heat pump system cooler (2-3) is divided into two paths, one of which is connected to the inlet of the CO2 heat pump system main valve (2-4), the outlet of the CO2 heat pump system main valve (2-4) is connected to the inlet of the CO2 heat pump system throttling device (2-5), and the other is connected to the inlet of the CO2 heat pump system bypass valve (2-6), the outlet of the CO2 heat pump system bypass valve (2-6) is connected to the outlet of the CO2 heat pump system throttling device (2-5) and then connected to the hot side inlet of the CO2 heat pump system cold storage heat exchanger (2-7), The hot side outlet of the cold storage heat exchanger (2-7) of the O2 heat pump system is connected to the inlet of the compressor (2-1) of the CO2 heat pump system, the cold side outlet of the cold storage heat exchanger (2-7) of the CO2 heat pump system is connected to the inlet of the cold storage tank (2-8) of the CO2 heat pump system, the outlet of the cold storage tank (2-8) of the CO2 heat pump system is connected to the inlet of the cold water pump (2-9) of the CO2 heat pump system, the outlet of the cold water pump (2-9) of the CO2 heat pump system is respectively connected to the cold side inlet of the supercritical CO2 precooler (1-5), the cold side inlet of the supercritical CO2 intercooler (1-7), and the cold side inlet of the low-temperature power generation system cooler (3-3), the cold side outlet of the supercritical CO2 precooler (1-5), the cold side outlet of the supercritical CO2 intercooler (1-7), and the cold side outlet of the low-temperature power generation system cooler (3-3) are respectively connected to the cold side inlet of the cold storage heat exchanger (2-7) of the CO2 heat pump system; The low-temperature power generation system comprises a low-temperature power generation system turbine (3-1), the outlet of the low-temperature power generation system turbine (3-1) is connected to the hot side inlet of the low-temperature power generation system regenerator (3-2), the hot side outlet of the low-temperature power generation system regenerator (3-2) is connected to the hot side inlet of the low-temperature power generation system cooler (3-3), the hot side outlet of the low-temperature power generation system cooler (3-3) is connected to the inlet of the low-temperature power generation system compressor (3-4), the outlet of the low-temperature power generation system compressor (3-4) is connected to the cold side inlet of the low-temperature power generation system regenerator (3-2), the cold side outlet of the low-temperature power generation system regenerator (3-2) is connected to the outlet of the low-temperature power generation system heater (3-5), and the outlet of the low-temperature power generation system compressor (3-4) is connected to the cold side inlet of the low-temperature power generation system regenerator (3-2). The cold side inlet is connected, the cold side outlet of the low temperature power generation system heater (3-5) is connected to the inlet of the low temperature power generation system turbine (3-1), the hot side outlet of the low temperature power generation system heater (3-5) is connected to the inlet of the low temperature power generation system heat storage working fluid pump (3-6), the outlet of the low temperature power generation system heat storage working fluid pump (3-6) is connected to the low temperature side inlet of the CO2 heat pump system heat storage heat exchanger (2-2), the low temperature side outlet of the CO2 heat pump system heat storage heat exchanger (2-2) is connected to the inlet of the low temperature power generation system heat storage tank (3-7), and the outlet of the low temperature power generation system heat storage tank (3-7) is connected to the hot side inlet of the low temperature power generation system heater (3-5); The supercritical CO2 primary compressor (1-6) and the supercritical CO2 secondary compressor (1-8) are coaxial and have the same rotation speed; The inlet pressure of the CO2 heat pump system compressor (2-1) is 3MPa-4MPa, and the outlet pressure is 24MPa-30MPa.

2. The working method of a supercritical CO2 Brayton cycle power generation system with electric thermal energy storage as claimed in claim 1, characterized in that: The supercritical CO2 Brayton cycle system is the main power generation system. During normal power generation, high-pressure CO2 first absorbs heat in the heat source (1-1) to become a high-temperature and high-pressure working fluid. The high-temperature and high-pressure working fluid enters the supercritical CO2 turbine (1-2) to generate power and becomes a low-pressure working fluid. The low-pressure working fluid first enters the hot side of the supercritical CO2 high-temperature regenerator (1-3), and then enters the hot side of the supercritical CO2 low-temperature regenerator (1-4) to release heat. Then the CO2 working fluid is divided into two paths. One path enters the hot side of the supercritical CO2 precooler (1-5) to continue to release heat. Then the low-temperature and low-pressure working fluid enters the supercritical CO2 primary compressor (1-6) for pressurization, and then enters The hot side of the supercritical CO2 intercooler (1-7) releases heat, and then enters the supercritical CO2 secondary compressor (1-8) to continue to increase the pressure. The pressurized working fluid enters the supercritical CO2 low-temperature regenerator (1-4) to absorb heat on the cold side. Another working fluid branched off from the hot side outlet of the supercritical CO2 low-temperature regenerator (1-4) directly enters the supercritical CO2 recompressor (1-9) to be pressurized, and then merges with the working fluid absorbed on the cold side of the supercritical CO2 low-temperature regenerator (1-4), enters the cold side of the supercritical CO2 high-temperature regenerator (1-3) to continue to absorb heat, and finally enters the heat source (1-1) to be heated to a predetermined temperature to complete the entire supercritical CO2 Brayton cycle; When there is no excess electricity in the power grid that needs to be stored, the main valve (2-4) of the CO2 heat pump system is closed, the bypass valve (2-6) of the CO2 heat pump system is opened, and the low-temperature power generation system does not work; at this time, the CO2 heat pump system only completes the role of the supercritical CO2 Brayton cycle system cooling system, and the CO2 heat pump system compressor (2-1) does not need to increase the pressure of the CO2 working fluid a lot, and only needs to overcome the flow resistance. The CO2 heat pump system compressor (2-1) drives the working fluid to flow through the CO2 heat pump system heat storage heat exchanger (2-2), and then enters the CO2 heat pump system cooler (2-3) to be cooled, and then the working fluid passes through the CO2 heat pump system bypass valve (2-6) and enters the hot side of the CO2 heat pump system cold storage heat exchanger (2-7), and finally Entering the CO2 heat pump system compressor (2-1) to complete a cooling circuit cycle; the cooling water circuit of the CO2 heat pump system maintains normal operation, and the cooling water in the CO2 heat pump system cold storage tank (2-8) is pumped out by the CO22 heat pump system cold water pump (2-9) and driven into the cold side of the CO2 precooler (1-5), the cold side of the supercritical CO2 intercooler (1-7), and the cold side of the low-temperature power generation system cooler (3-3); after absorbing heat, the cooling water flows out from the cold side of the CO2 precooler (1-5), the cold side of the supercritical CO2 intercooler (1-7), and the cold side of the low-temperature power generation system cooler (3-3), and then flows into the cold side of the CO2 heat pump system cold storage heat exchanger (2-7) to be cooled, and then returns to the CO2 heat pump system cold storage tank (2-8); When there is excess electricity in the power grid that needs to be stored, the main valve (2-4) of the CO2 heat pump system is opened, the bypass valve (2-6) of the CO2 heat pump system is closed, and the low-temperature power generation system does not work; at this time, the CO2 heat pump system not only plays the role of a supercritical CO2 Brayton cycle system cooling system, but also stores excess electricity as heat energy; the CO2 heat pump system compressor (2-1) increases the pressure of the CO2 working fluid, and the excess electricity is converted into heat and electricity through the work of the CO2 heat pump system compressor (2-1), and the working fluid after being pressurized and heated flows through the CO2 heat pump system heat storage heat exchanger (2 -2) The hot side releases heat to the heat storage medium, and then enters the CO2 heat pump system cooler (2-3) to be cooled, and then passes through the CO2 heat pump system main valve (2-4), throttles and reduces the temperature in the CO2 heat pump system throttling device (2-5), and then releases the low-temperature cold energy to the cooling water on the hot side of the CO2 heat pump system cold storage heat exchanger (2-7); the low-temperature power generation system heat storage medium pump (3-6) transports the high-temperature heat storage medium to the low-temperature side of the CO2 heat pump system heat storage heat exchanger (2-2) to absorb heat, and then stores it in the low-temperature power generation system heat storage tank (3-7); When the power grid needs to supplement more electric energy, the low-temperature power generation system starts to work, and the supercritical CO2 Brayton cycle system and the CO2 heat pump system continue to work; the high-temperature medium stored in the low-temperature power generation system heat storage tank (3-7) flows into the hot side of the low-temperature power generation system heater (3-5) to release heat, and then continues to absorb heat from the CO2 heat pump system heat storage heat exchanger (2-2) through the low-temperature power generation system heat storage working medium pump (3-6) and returns to the low-temperature power generation system heat storage tank (3-7); the low-temperature power generation working medium is heated on the cold side of the low-temperature power generation system heater (3-5) and enters the low-temperature power generation system turbine (3-1) to perform work, and the working medium after performing work releases heat on the hot side of the low-temperature power generation system regenerator (3-2), and then enters the low-temperature power generation system cooler (3-3) to continue to be cooled, and the cooled medium enters the low-temperature side of the low-temperature power generation system regenerator (3-2) to absorb heat through the boost of the low-temperature power generation system compressor (3-4), and then enters the cold side of the low-temperature power generation system heater (3-5) to continue to be heated, completing the entire cycle.

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