Coupling power circulation system and method capable of storing and releasing energy

Abstract

The invention relates to the technical field of physical energy storage and thermal power generation, in particular to a coupling power circulation system and method capable of storing and releasing energy, and the circulation system comprises a CO2 Brayton / Brayton-Rankine cycle subsystem, a CO2 energy storage subsystem and a LiBr absorption refrigeration system. CO2 is transmitted between the CO2 energy storage subsystem and the CO2 Brayton / Brayton-Rankine cycle subsystem; the CO2 Brayton / Brayton-Rankine cycle subsystem is used for generating power through CO2; and the LiBr absorption refrigeration system refrigerates CO2 of the CO2 energy storage subsystem according to waste heat of the CO2 Brayton / Brayton-Rankine cycle subsystem. When the coupling power circulation system stores energy, different systems can be adopted for operation according to different seasons, seasonal renewable energy sources such as surplus electric energy or surplus solar energy of a power grid are stored in the CO2 energy storage subsystem, and the electric energy input into the power grid is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of physical energy storage and thermal power generation, and more specifically, to a coupled power cycle system and method capable of storing and releasing energy. Background Art

[0002] With the rapid development of new energy generation such as wind power and solar power generation, after the introduction of new energy generation such as wind power and solar power generation into the power grid power supply system for power supply, the balance of the power supply system is easily destroyed because new energy generation such as wind power and solar power generation depends on the external environment and has randomness and intermittence. In addition, the electricity demand in different periods of the same day and in different seasons is also different, which will further increase the difficulty of keeping the power supply system in dynamic balance. Therefore, after the introduction of new energy generation such as wind power and solar power generation, it is difficult to align the peak power generation and peak power consumption of the power supply system, and it is difficult for the power supply system to maintain dynamic balance and achieve the purpose of stable power supply. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiency of the prior art that the power supply system is difficult to maintain dynamic balance after the introduction of new energy sources such as wind power and solar power generation, and to provide a coupled power circulation system and method that can store and release energy. This scheme can flexibly regulate the input and output of the power supply system, so that the power supply system maintains dynamic balance and provides stable power supply.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A coupled power cycle system capable of storing and releasing energy is provided, comprising: CO 2 Brayton / Brayton-Rankine cycle subsystem, CO 2 Energy storage subsystem and LiBr absorption refrigeration system, the CO 2 The energy storage subsystem is used to supply the CO 2 The Brayton / Brayton-Rankine cycle subsystem inputs working fluid or receives CO 2 The working fluid of the Brayton / Brayton-Rankine cycle subsystem; the CO 2 Brayton / Brayton-Rankine cycle subsystem and the CO 2 The energy storage subsystem is connected to the LiBr absorption refrigeration system to 2 The working fluid provided by the energy storage subsystem is used to generate electricity; the LiBr absorption refrigeration system is used to generate electricity according to the CO 2 The waste heat of the Brayton / Brayton-Rankine cycle subsystem is used to 2 The working fluid of the energy storage subsystem is used for cooling.

[0006] When the ambient temperature is high and the grid load is small, CO 2 The Brayton / Brayton-Rankine cycle subsystem is coupled with the LiBr absorption refrigeration system, which utilizes CO 2 Waste heat from Brayton / Brayton-Rankine cycle subsystems to CO 2 Cooled and stored in CO 2 In the energy storage subsystem, energy is stored; when the ambient temperature is low and the grid load is small, CO 2 Cooled and stored in CO 2 In the energy storage subsystem, LiBr absorption refrigeration system and CO 2 The energy storage subsystem is coupled to the LiBr absorption refrigeration system to cool the CO 2 Cooled and stored in CO 2 In the energy storage subsystem. When the grid load is large, CO 2 The waste heat from the Brayton / Brayton-Rankine cycle subsystem is used to evaporate CO 2 CO in the energy storage subsystem 2 , enter CO 2 CO of the Brayton / Brayton-Rankine cycle subsystem 2 Doing work generates electricity and releases energy.

[0007] The coupled power cycle system of the present invention can use different systems to operate according to different seasons when storing energy, and store seasonal renewable energy such as surplus electricity from the power grid or surplus solar energy in CO 2 In the energy storage subsystem, the electric energy input to the grid is reduced; when releasing energy, the energy storage system is connected to the power generation cycle to release energy, increase the output power of the power generation cycle, and increase the electric energy input to the grid. The energy storage system can make full use of the existing equipment of the power plant, reduce costs, and the power generation system can adapt to a variety of heat source scenarios and achieve flexible peak load regulation. After verification, it was found that the compressed CO 2 The round-trip efficiency exceeds 100% and can reach 150%, which means that the additional electricity generated by the energy release mode exceeds the electricity consumed by the energy storage mode. The round-trip efficiency of a general compressed gas energy storage system is about 50%-70%, which is a significant improvement compared with existing technologies.

[0008] Preferably, the CO 2 The energy storage subsystem includes a main compressor, a turbine, and a low-pressure CO 2 Storage tank, pump 1, first cooler, pump 2, second cooler and high pressure CO 2 Storage tank, the low pressure CO 2 The CO storage tank 2 The Brayton / Brayton-Rankine cycle subsystem is connected to the main compressor and the turbine.2 After being cooled by the low-temperature environment, it is pressurized and cooled by a two-stage pump and two intercoolers and stored in high-pressure CO 2 In storage tank.

[0009] Preferably, the LiBr absorption refrigeration system comprises a generator, a condenser, an evaporator and an absorber connected in sequence, a regenerator, a pump three and a first throttle valve are provided between the generator and the absorber, the working fluid in the absorber passes through the pump three and the regenerator in sequence to enter the generator; the working fluid in the generator passes through the regenerator and the first throttle valve in sequence to enter the absorber, and a second throttle valve is provided between the condenser and the evaporator. First, the circulating stream with the waste heat of the power cycle passes through the generator to evaporate the LiBr solution, and the stream is divided into two sections: the first section of the LiBr concentrated solution is expanded and cooled through the first throttle valve after heat release, and enters the absorber. It is mixed with the saturated water flowing out of the evaporator to become a dilute LiBr solution again, enters the pump three for pressurization, flows into the regenerator for heating, and then enters the generator to complete the solution cycle; the second section of the superheated water vapor flows into the condenser to cool down to become a relatively low temperature superheated steam or saturated steam, and then flows into the second throttle valve for expansion and cooling, and the temperature is about 6°C. Entering the evaporator Eva refrigeration CO 2 The stream or stores cold energy and enters the absorber after absorbing heat.

[0010] Preferably, the CO 2 The Brayton / Brayton-Rankine cycle subsystem includes a Brayton-Rankine hybrid cycle system, which includes a heat source heater, a high-temperature regenerator, a medium-temperature regenerator, a low-temperature regenerator, a recompressor, a cooler and a pump four. The working fluid in the turbine passes through the high-temperature regenerator, the medium-temperature regenerator and the low-temperature regenerator in sequence and enters the cooler; the working fluid in the cooler passes through the pump four, the low-temperature regenerator, the medium-temperature regenerator, the high-temperature regenerator and the heat source heater in sequence and enters the turbine; the working fluid flowing out of the medium-temperature regenerator also passes through the recompressor and flows into the high-temperature regenerator; the working fluid flowing out of the low-temperature regenerator also passes through the main compressor and flows into the medium-temperature regenerator.

[0011] Preferably, the CO 2 The Brayton / Brayton-Rankine cycle subsystem includes a recompression Brayton power cycle system, which includes a heat source heater, a high-temperature regenerator, a low-temperature regenerator, a recompressor and a cooler. The working fluid in the turbine passes through the high-temperature regenerator and the low-temperature regenerator in sequence and enters the cooler; the working fluid in the cooler passes through the main compressor, the low-temperature regenerator, the high-temperature regenerator and the heat source heater in sequence and enters the turbine; the working fluid flowing out of the low-temperature regenerator also passes through the recompressor and flows into the high-temperature regenerator.

[0012] A coupled power cycle method capable of storing and releasing energy includes an energy release cycle and an energy storage cycle, wherein the energy storage cycle includes a high-temperature energy storage cycle and a low-temperature energy storage cycle. Before performing the coupled power cycle, the working load of the power grid is first judged. If the working load of the power grid is large, the energy release cycle is entered; if the working load of the power grid is small, the working environment of the power grid is further judged. If it is in a low-temperature environment, the low-temperature energy storage cycle is entered; if it is in a high-temperature environment, the high-temperature energy storage cycle is entered.

[0013] The coupled power cycle method capable of storing and releasing energy of the present invention has a plurality of operation modes in the energy storage stage, can make full use of the cold source of the low-temperature environment, can increase the energy storage power when the cold energy is sufficient, is only strongly coupled with the pump or main compressor of the power cycle, has strong flexibility, and has almost no effect on other equipment of the power cycle.

[0014] Preferably, the coupled power cycle system under the energy release cycle is the coupled power cycle system described above, comprising the following working steps: first, high-pressure liquid CO 2 From high pressure CO 2 The CO2 discharged from the storage tank, with a pressure and temperature of 25 MPa and 25°C respectively, flows into the regenerator and evaporates until the CO2 discharged from the regenerator is 2 Temperature and CO at the outlet of the main compressor 2 The temperature is the same. CO flowing out of the regenerator 2 Temperature and CO at the main compressor outlet 2 After mixing, it flows through the splitter to the low-pressure CO 2 The storage tank is condensed to 25℃ by the cold storage device and then stored in low-pressure CO 2 In the tank, low pressure CO 2 The storage pressure of the tank is 8.5MPa, which is the same as the main compressor inlet CO 2 The pressure is the same.

[0015] Preferably, the coupled power cycle system under the high temperature energy storage cycle is the coupled power cycle system described above, comprising the following working steps: 2 Low temperature and low pressure CO flowing out of the storage tank 2 The high-temperature and high-pressure CO2 is absorbed by the regenerator and enters the high-temperature regenerator. 2 The waste heat is heated to a preset temperature and then mixed with the main circulating flow to enter the main compressor inlet. The main compressor consumes additional electricity or work to compress CO 2 . CO from the main compressor 2 The flow is split, and one stream is condensed into liquid CO at 25 MPa and 25°C through the evaporator. 2 and stored in high pressure CO 2The other stream continues to flow into the medium temperature regenerator as the main circulation stream, and the outlet of the medium temperature regenerator is connected with the stream CO from the recompressor. 2 Mixed, mixed CO 2 It flows through the high-temperature regenerator, heat source heater and turbine in sequence, and outputs electrical energy when the turbine performs work, which can be fed into the power grid or supplied to the main compressor for energy storage. 2 After passing through the high-temperature regenerator and the medium-temperature regenerator to release the waste heat, it flows into the cooler to exchange heat with the environment to raise the temperature to 35°C, completing a cycle.

[0016] Preferably, the coupled power cycle system under the low temperature energy storage cycle is the above-mentioned coupled power cycle system, comprising the following working steps: low pressure CO 2 Low-pressure liquid CO flowing out of the storage tank 2 The gas is cooled by the low-temperature environment and then pressurized and cooled by two-stage pumps and two coolers and stored in high-pressure CO 2 The pump can be driven by turbine T.

[0017] Preferably, the coupled power cycle system under the low temperature energy storage cycle is the above-mentioned coupled power cycle system, comprising the following working steps: low pressure CO 2 Liquid CO at the tank outlet 2 It flows into the cooler, is cooled by the low temperature environment, flows into the mixer and mixes with the main circulation flow, and then flows into the pump to be pressurized. The pressurized CO 2 The flow is split by the splitter, one stream flows into the high-temperature regenerator after passing through the regenerator, and the other stream flows into the low-temperature regenerator in the main cycle. 2 Evaporation into supercritical CO through a low temperature regenerator 2 and the CO at the outlet of the main compressor 2 Mixed in the mixer, the mixed CO 2 The CO2 flows into the medium temperature heat exchanger to absorb heat, and the CO2 flows out of the medium temperature heat exchanger. 2 CO at the recompressor outlet 2 After mixing, it flows into the high-temperature regenerator and the heat source heater in turn to absorb heat. 2 The CO2 enters the turbine and expands to do work. 2 The waste heat is released through the high-temperature regenerator and the medium-temperature regenerator. The CO 2 The flow is split in the splitter, one stream flows into the recompressor and the other flows into the low-temperature regenerator; the CO flowing out of the low-temperature regenerator 2 One stream enters the main compressor for compression, and the other stream is cooled into liquid by the environment and then coupled with the energy storage system to complete a cycle.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The coupled power cycle system capable of storing and releasing energy of the present invention can adopt different system operations according to different seasons when storing energy, and store the surplus electric energy of the power grid or the surplus solar energy and other seasonal renewable energy in CO 2 In the energy storage subsystem, the electric energy input to the grid is reduced; when releasing energy, the energy storage system is connected to the power generation cycle to release energy, increase the output power of the power generation cycle, and increase the electric energy input to the grid. The energy storage system can make full use of the existing equipment of the power plant, reduce costs, and the power generation system can adapt to a variety of heat source scenarios and achieve flexible peak regulation.

[0020] A CO2-releasing coupled power cycle system capable of storing and releasing energy according to the present invention 2 The Brayton / Brayton-Rankine cycle subsystem includes a Brayton-Rankine hybrid cycle system and a recompression Brayton power cycle system, coupled with a CO 2 After the energy storage subsystem is installed, the heat source utilization rate of the energy storage system is greatly improved compared with the conventional energy storage system, which can improve the round-trip efficiency of the energy storage system.

[0021] The present invention provides a coupled power cycle method capable of storing and releasing energy. In the energy storage stage, there are multiple operating modes, which can fully utilize the cold source of the low-temperature environment. The energy storage power can be increased when the cold energy is sufficient. It is only strongly coupled with the pump or main compressor of the power cycle, has strong flexibility, and has almost no effect on other equipment in the power cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The schematic diagram of the LiBr absorption refrigeration system structure is a coupled power cycle system that can store and release energy. The arrows in the figure represent CO 2 Flow direction;

[0023] Figure 2 The flowchart of a high-temperature energy release cycle of a coupled power cycle method for storing and releasing energy is shown in Figure 1. The arrows in the figure represent CO 2 Flow direction;

[0024] Figure 3 Figure 1 is a flow chart of a low-temperature energy storage cycle for a coupled power cycle method that can store and release energy. The arrows in the figure represent CO 2 Flow direction;

[0025] Figure 4 Figure 1 is a flow chart of another low-temperature energy storage cycle for a coupled power cycle method that can store and release energy. The arrows in the figure represent CO 2 Flow direction;

[0026] Figure 5 Figure 1 is a flow chart of a high-temperature energy storage cycle for a coupled power cycle method that can store and release energy. The arrows in the figure represent CO 2 Flow direction.

[0027] In the attached figure: 1. Low pressure CO2 Storage tank; 2. High pressure CO 2 Storage tank; 3. First cooler; 4. Second cooler; 5. Pump one; 6. Pump two; 7. Generator; 8. Condenser; 9. Evaporator; 10. Absorber; 11. Regenerator; 12. Pump three; 13. First throttle valve; 14. Heat source heater; 5. Turbine; 16. High-temperature regenerator; 17. Medium-temperature regenerator; 18. Low-temperature regenerator; 19. Main compressor; 20. Recompressor; 21. Cooler; 22. Pump four. DETAILED DESCRIPTION

[0028] The present invention is further described below in conjunction with specific implementation methods. The accompanying drawings are only used for exemplary descriptions and are only schematic diagrams, not actual drawings, and cannot be understood as limiting this patent; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the accompanying drawings may be omitted.

[0029] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as limitations on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0030] Embodiment 1

[0031] This embodiment is a first embodiment of a coupled power cycle system capable of storing and releasing energy, comprising: CO 2 Brayton / Brayton-Rankine cycle subsystem, CO 2 Energy storage subsystem and LiBr absorption refrigeration system, CO 2 The energy storage subsystem is used to 2 The Brayton / Brayton-Rankine cycle subsystem inputs working fluid or receives CO 2 Working fluid of Brayton / Brayton-Rankine cycle subsystem; CO 2 Brayton / Brayton-Rankine cycle subsystem and CO 2 The energy storage subsystem is connected to the LiBr absorption refrigeration system to 2 The working fluid provided by the energy storage subsystem is used to generate electricity; the LiBr absorption refrigeration system is used to generate electricity according to the CO 2Waste heat from Brayton / Brayton-Rankine cycle subsystems to CO 2 The working fluid of the energy storage subsystem is used for cooling.

[0032] Specifically, CO 2 The energy storage subsystem includes a main compressor 19, a turbine 15 and a low-pressure CO 2 Storage tank 1, pump 1 5, first cooler 3, pump 2 6, second cooler 4 and high pressure CO 2 Tank 2, low pressure CO 2 Tank 1 passes CO 2 The Brayton / Brayton-Rankine cycle subsystem is connected to the main compressor 19 and the turbine 15. Low-pressure liquid CO 2 After being cooled by the low temperature environment, it is pressurized and cooled by a two-stage pump and two intercoolers 21 and stored in high-pressure CO 2 In storage tank 2.

[0033] Specifically, Figure 1 As shown, the LiBr absorption refrigeration system includes a generator 7, a condenser 8, an evaporator 9 and an absorber 10 which are connected in sequence. A regenerator 11, a pump 3 12 and a first throttle valve 13 are arranged between the generator 7 and the absorber 10. The working fluid in the absorber 10 passes through the pump 3 12 and the regenerator 11 in sequence and enters the generator 7; the working fluid in the generator 7 passes through the regenerator 11 and the first throttle valve 13 in sequence and enters the absorber 10. A second throttle valve is arranged between the condenser 8 and the evaporator 9.

[0034] Specifically, CO 2 The Brayton / Brayton-Rankine cycle subsystem includes a recompression Brayton power cycle system, which includes a heat source heater 14, a high-temperature regenerator 16, a low-temperature regenerator 18, a recompressor 20 and a cooler 21. The working fluid in the turbine 15 passes through the high-temperature regenerator 16 and the low-temperature regenerator 18 in sequence and enters the cooler 21; the working fluid in the cooler 21 passes through the main compressor 19, the low-temperature regenerator 18, the high-temperature regenerator 16 and the heat source heater 14 in sequence and enters the turbine 15; the working fluid flowing out of the low-temperature regenerator 18 also passes through the recompressor 20 and flows into the high-temperature regenerator 16.

[0035] The working principle of this embodiment is as follows:

[0036] When the ambient temperature is high and the grid load is small, CO 2 The Brayton / Brayton-Rankine cycle subsystem is coupled with the LiBr absorption refrigeration system, which utilizes CO 2 Waste heat from Brayton / Brayton-Rankine cycle subsystems to CO 2 Cooled and stored in CO 2In the energy storage subsystem, energy is stored; when the ambient temperature is low and the grid load is small, CO 2 Cooled and stored in CO 2 In the energy storage subsystem, LiBr absorption refrigeration system and CO 2 The energy storage subsystem is coupled to the LiBr absorption refrigeration system to cool the CO 2 Cooled and stored in CO 2 In the energy storage subsystem. When the grid load is large, CO 2 The waste heat from the Brayton / Brayton-Rankine cycle subsystem is used to evaporate CO 2 CO in the energy storage subsystem 2 , enter CO 2 CO of the Brayton / Brayton-Rankine cycle subsystem 2 Doing work generates electricity and releases energy.

[0037] The beneficial effects of this embodiment are as follows:

[0038] The coupled power cycle system of this scheme can use different systems to operate according to different seasons when storing energy, and store seasonal renewable energy such as surplus electricity from the power grid or surplus solar energy in CO2. 2 In the energy storage subsystem, the electric energy input to the grid is reduced; when releasing energy, the energy storage system is connected to the power generation cycle to release energy, increase the output power of the power generation cycle, and increase the electric energy input to the grid. The energy storage system can make full use of the existing equipment of the power plant, reduce costs, and the power generation system can adapt to a variety of heat source scenarios and achieve flexible peak regulation.

[0039] Embodiment 2

[0040] This embodiment is a second embodiment of a coupled power cycle system capable of storing and releasing energy. This embodiment is similar to the first embodiment, except that CO 2 The structure of the Brayton / Brayton-Rankine cycle subsystems is different.

[0041] Specifically, sCO 2 -CO 2The Brayton-hybrid cycle system includes a Brayton-Rankine hybrid power cycle system, which includes a heat source heater 14, a high-temperature regenerator 16, a medium-temperature regenerator 17, a low-temperature regenerator 18, a recompressor 20, a cooler 21 and a pump four 22. The working fluid in the turbine 15 passes through the high-temperature regenerator 16, the medium-temperature regenerator 17 and the low-temperature regenerator 18 in sequence and enters the cooler 21; the working fluid in the cooler 21 passes through the pump four 22, the low-temperature regenerator 18, the medium-temperature regenerator 17, the high-temperature regenerator 16 and the heat source heater 14 in sequence and enters the turbine 15; the working fluid flowing out of the medium-temperature regenerator 17 also passes through the recompressor 20 and flows into the high-temperature regenerator 16; the working fluid flowing out of the low-temperature regenerator 18 also passes through the main compressor 19 and flows into the medium-temperature regenerator 17.

[0042] Other features and beneficial effects of this embodiment are the same as those of the first embodiment.

[0043] Embodiment 3

[0044] This embodiment is an embodiment of a coupled power circulation method capable of storing and releasing energy. Based on the first and second embodiments, this embodiment further defines the power circulation method of the coupled system.

[0045] Specifically, a coupled power cycle method capable of storing and releasing energy includes an energy release cycle and an energy storage cycle. The energy storage cycle includes a high-temperature energy storage cycle and a low-temperature energy storage cycle. Before performing the coupled power cycle, the working load of the power grid is first judged. If the working load of the power grid is large, the energy release cycle is entered; if the working load of the power grid is small, the working environment of the power grid is further judged. If it is in a low-temperature environment, the low-temperature energy storage cycle is entered; if it is in a high-temperature environment, the high-temperature energy storage cycle is entered.

[0046] Specifically, the coupled power cycle system under the energy release cycle is the coupled power cycle system of Example 1, such as Figure 2 As shown, the process includes the following steps: first, high pressure liquid CO 2 From high pressure CO 2 The CO2 discharged from the storage tank 2, with a pressure and temperature of 25 MPa and 25°C respectively, flows into the regenerator 11 and evaporates until the CO2 discharged from the regenerator 11 is 2 Temperature and CO at the outlet of the main compressor 19 2 The temperature is the same. CO flowing out of the regenerator 11 2 Temperature and CO at the outlet of the main compressor 19 2 After mixing, it flows through the splitter to the low-pressure CO 2 Storage tank 1, condensed to 25℃ by the cold storage device and stored in low pressure CO 2 In tank 1, low pressure CO 2 The storage pressure of tank 1 is 8.5MPa, and the inlet CO 2 The pressure is the same.

[0047] Specifically, the coupled power cycle system under the high temperature energy storage cycle is the coupled power cycle system as in the first embodiment, such as Figure 3 As shown, the following working steps are included: from low pressure CO 2 Low temperature and low pressure CO flowing out of tank 1 2 The high-temperature and high-pressure CO2 is absorbed by the regenerator 11 and enters the high-temperature regenerator 16. 2 The waste heat is heated to a preset temperature and mixed with the main circulating flow to enter the inlet of the main compressor 19. The main compressor 19 consumes additional electrical energy or work to compress CO 2 The CO flowing out from the main compressor 19 2 The flow is split, and one stream is condensed into liquid CO at 25 MPa and 25°C through evaporator 9. 2 and stored in high pressure CO 2 another stream continues to flow into the medium temperature regenerator 17 as the circulating mainstream stream, and the outlet of the medium temperature regenerator 17 and the stream CO from the recompressor 20 2 Mixed, mixed CO 2 The CO2 flows through the high temperature regenerator 16, the heat source heater 14 and the turbine 15 in sequence, and the turbine 15 performs work to output electrical energy, which can be fed into the power grid or supplied to the main compressor 19 for energy storage. 2 After passing through the high-temperature regenerator 16 and the medium-temperature regenerator 17 to release the waste heat, it flows into the cooler 21 to exchange heat with the environment to raise the temperature to 35° C., completing a cycle.

[0048] Specifically, the coupled power cycle system under the low temperature energy storage cycle is the coupled power cycle system of the first embodiment, such as Figure 4 As shown, it includes the following working steps: low pressure CO 2 Low-pressure liquid CO flowing out of tank 1 2 The gas is cooled by the low temperature environment and then pressurized and cooled by a two-stage pump and two coolers 21 and stored in high-pressure CO 2 In the storage tank 2. The pump can be driven by the turbine 15.

[0049] Specifically, the coupled power cycle system under the low temperature energy storage cycle is the coupled power cycle system of the second embodiment, such as Figure 5 As shown, it includes the following working steps: low pressure CO 2 Liquid CO at the outlet of tank 1 2 It flows into the cooler 21, is cooled by the low temperature environment, flows into the mixer and mixes with the main circulation flow, and then flows into the pump to be pressurized. The pressurized CO 2 The flow is split by the splitter, one stream flows through the regenerator 11 and then flows into the high-temperature regenerator 16, and the other stream flows into the low-temperature regenerator 18 in the main cycle. 2It is evaporated into supercritical CO by the low temperature regenerator 18 2 and the CO at the outlet of the main compressor 19 2 Mixed in the mixer, the mixed CO 2 The CO flows into the medium temperature heat exchanger 17 to absorb heat, and the CO flowing out of the medium temperature heat exchanger 17 2 The CO at the outlet of the recompressor 20 2 After mixing, it flows into the high temperature heat regenerator 16 and the heat source heater 14 in turn to absorb heat. 2 The CO2 enters the turbine 15 and expands to do work. The CO2 flows out of the turbine 15. 2 The CO at the outlet of the medium temperature regenerator 17 is discharged through the high temperature regenerator 16 and the medium temperature regenerator 17 to release the waste heat. 2 The flow is split in the splitter, one of which flows into the recompressor 20 and the other flows into the low-temperature regenerator 18; the CO flowing out of the low-temperature regenerator 18 2 One stream enters the main compressor 19 for compression, and the other stream is cooled by the environment into a liquid state and then coupled to the energy storage system to complete a cycle.

[0050] The beneficial effects of this embodiment are as follows: a coupled power cycle method capable of storing and releasing energy of the present invention has a variety of operating modes in the energy storage stage, can make full use of the cold source of the low-temperature environment, can increase the energy storage power when the cold energy is sufficient, is only strongly coupled with the pump or main compressor 19 of the power cycle, has strong flexibility, and has almost no effect on other equipment in the power cycle.

[0051] In the specific contents of the above-mentioned specific implementation methods, the various technical features can be combined in any non-contradictory manner. In order to make the description concise, not all possible combinations of the above-mentioned technical features are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A coupled power cycle system capable of storing and releasing energy, characterized in that: include: CO2 Brayton / Brayton-Rankine cycle subsystem, CO2 energy storage subsystem and LiBr absorption refrigeration system, The CO2 energy storage subsystem is used to input working fluid into the CO2 Brayton / Brayton-Rankine cycle subsystem or receive working fluid from the CO2 Brayton / Brayton-Rankine cycle subsystem; The CO2 Brayton / Brayton-Rankine cycle subsystem is connected to the CO2 energy storage subsystem and the LiBr absorption refrigeration system to generate electricity based on the working fluid provided by the CO2 energy storage subsystem; The LiBr absorption refrigeration system is used to refrigerate the working fluid of the CO2 energy storage subsystem based on the waste heat of the CO2 Brayton / Brayton-Rankine cycle subsystem.

2. A coupled power cycle system capable of storing and releasing energy according to claim 1, characterized in that: The CO2 energy storage subsystem comprises a main compressor (19), a turbine (15), and a low-pressure CO2 storage tank (1), a pump one (5), a first cooler (3), a pump two (6), a second cooler (4) and a high-pressure CO2 storage tank (2) connected in sequence, wherein the low-pressure CO2 storage tank (1) is connected to the main compressor (19) and the turbine (15) via the CO2 Brayton / Brayton-Rankine cycle subsystem.

3. A coupled power cycle system capable of storing and releasing energy according to claim 2, characterized in that: The LiBr absorption refrigeration system comprises a generator (7), a condenser (8), an evaporator (9) and an absorber (10) which are connected in sequence; a regenerator (11), a pump three (12) and a first throttle valve (13) are provided between the generator (7) and the absorber (10); the working fluid in the absorber (10) passes through the pump three (12) and the regenerator (11) in sequence and enters the generator (7); the working fluid in the generator (7) passes through the regenerator (11) and the first throttle valve (13) in sequence and enters the absorber (10); a second throttle valve is provided between the condenser (8) and the evaporator (9).

4. A coupled power cycle system capable of storing and releasing energy according to claim 3, characterized in that: The CO2 Brayton / Brayton-Rankine cycle subsystem includes a Brayton-Rankine hybrid cycle system, and the Brayton-Rankine hybrid cycle system includes a heat source heater (14), a high temperature regenerator (16), a medium temperature regenerator (17), a low temperature regenerator (18), a recompressor (20), a cooler (21) and a pump four (22), The working fluid in the turbine (15) passes through the high-temperature regenerator (16), the medium-temperature regenerator (17) and the low-temperature regenerator (18) in sequence and enters the cooler (21); The working fluid in the cooler (21) passes through the pump 4 (22), the low-temperature regenerator (18), the medium-temperature regenerator (17), the high-temperature regenerator (16) and the heat source heater (14) in sequence and enters the turbine (15); The working fluid flowing out of the medium-temperature regenerator (17) also passes through the re-compressor (20) and flows into the high-temperature regenerator (16); the working fluid flowing out of the low-temperature regenerator (18) also passes through the main compressor (19) and flows into the medium-temperature regenerator (17).

5. A coupled power cycle system capable of storing and releasing energy according to claim 3, characterized in that: The CO2 Brayton / Brayton-Rankine cycle subsystem includes a recompression Brayton power cycle system, and the recompression Brayton power cycle system includes a heat source heater (14), a high temperature regenerator (16), a low temperature regenerator (18), a recompressor (20) and a cooler (21). The working fluid in the turbine (15) passes through the high-temperature regenerator (16) and the low-temperature regenerator (18) in sequence and enters the cooler (21); The working fluid in the cooler (21) passes through the main compressor (19), the low-temperature regenerator (18), the high-temperature regenerator (16) and the heat source heater (14) in sequence and enters the turbine (15); The working fluid flowing out of the low-temperature regenerator (18) also passes through the recompressor (20) and flows into the high-temperature regenerator (16).

6. A coupled power cycle method capable of storing and releasing energy, characterized in that: It includes an energy release cycle and an energy storage cycle, wherein the energy storage cycle includes a high-temperature energy storage cycle and a low-temperature energy storage cycle. Before carrying out the coupled power cycle, the grid workload is first determined. If the grid workload is large, the energy release cycle is entered; If the grid workload is small, the grid working environment will continue to be judged. If it is in a low temperature environment, it will enter a low temperature energy storage cycle; if it is in a high temperature environment, it will enter a high temperature energy storage cycle.

7. A coupled power cycle method capable of storing and releasing energy according to claim 6, characterized in that: The coupled power cycle system under the low temperature energy storage cycle is the coupled power cycle system as claimed in claim 4, comprising the following steps: The liquid CO2 at the outlet of the low-pressure CO2 storage tank (1) flows into the cooler (21), is cooled by the low-temperature environment, flows into the mixer, is mixed with the main circulation flow, flows into the pump and is pressurized, and the pressurized CO2 is split by the splitter, one stream flows through the regenerator (11) and flows into the high-temperature regenerator (16), and the other stream flows into the low-temperature regenerator (18) in the main circulation. The CO2 flowing into the low-temperature regenerator (18) is evaporated into supercritical CO2 through the low-temperature regenerator (18) and is mixed with the CO2 at the outlet of the main compressor (19) in the mixer. The mixed CO2 flows into the medium-temperature regenerator (17) to absorb heat, and the CO2 flowing out of the medium-temperature regenerator (17) is After mixing with the CO2 at the outlet of the recompressor (20), the CO2 flows into the high-temperature regenerator (16) and the heat source heater (14) in sequence to absorb heat. The CO2 after absorbing heat enters the turbine (15) to expand and do work. The CO2 flowing out of the turbine (15) flows through the high-temperature regenerator (16) and the medium-temperature regenerator (17) to release waste heat. The CO2 at the outlet of the medium-temperature regenerator (17) is split in the splitter, one stream flows into the recompressor (20) and the other stream flows into the low-temperature regenerator (18); one stream of the CO2 flowing out of the low-temperature regenerator (18) enters the main compressor (19) for compression, and the other stream is cooled into liquid by the environment and coupled to the energy storage system to complete a cycle.

8. A coupled power cycle method capable of storing and releasing energy according to claim 6, characterized in that: The coupled power cycle system under the high temperature energy storage cycle is the coupled power cycle system according to claim 5, wherein the high temperature energy storage cycle comprises the following steps: The low-temperature, low-pressure CO2 flowing out of the low-pressure CO2 storage tank (1) passes through the regenerator (11) to absorb the waste heat of the high-temperature, high-pressure CO2 entering the high-temperature regenerator (16), and after being heated to a preset temperature, is mixed with the main circulation flow and enters the inlet of the main compressor (19). The main compressor (19) consumes additional electrical energy or work to compress the CO2. The CO2 flowing out of the main compressor (19) is split, one stream is condensed into liquid CO2 through the evaporator (9) and stored in the high-pressure CO2 storage tank (2); the other stream continues to be condensed into liquid CO2 through the evaporator (9) and stored in the high-pressure CO2 storage tank (2); The main stream for circulation flows into the medium-temperature reheater (17), and the outlet of the medium-temperature reheater (17) is mixed with the stream CO2 from the recompressor (20). The mixed CO2 flows through the high-temperature reheater (16), the heat source heater (14) and the turbine (15) in sequence. The turbine (15) performs work to output electrical energy. The CO2 at the outlet of the turbine (15) flows through the high-temperature reheater (16) and the medium-temperature reheater (17) to release the waste heat, and then flows into the cooler (21) to exchange heat with the environment to increase the temperature, thus completing a cycle.

9. A coupled power cycle method capable of storing and releasing energy according to claim 6, characterized in that: The coupled power cycle system under the low temperature energy storage cycle is the coupled power cycle system as claimed in claim 5, comprising the following steps: The low-pressure liquid CO2 flowing out of the low-pressure CO2 storage tank (1) is cooled by the low-temperature environment, and then pressurized and cooled by a two-stage pump and two coolers (21) and stored in the high-pressure CO2 storage tank (2).

10. A coupled power cycle method capable of storing and releasing energy according to claim 6, characterized in that: The coupled power cycle system under the energy release cycle is the coupled power cycle system according to claim 5, wherein the energy release cycle comprises the following steps: First, high-pressure liquid CO2 flows out from the high-pressure CO2 storage tank (2) and flows into the regenerator (11) to evaporate until the temperature of the CO2 flowing out of the regenerator (11) is the same as the temperature of the CO2 at the outlet of the main compressor (19). The CO2 flowing out of the regenerator (11) and the CO2 at the outlet of the main compressor (19) are mixed and then flow to the low-pressure CO2 storage tank (1) through the diverter, and then condensed by the cold storage device and stored in the low-pressure CO2 storage tank (1).

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