Solar molten salt heat storage and electric energy storage coupled CO2 cycle power generation system and method

Abstract

The invention discloses a solar fused salt heat storage and electric energy storage coupled CO2 cycle power generation system and method.The system comprises a solar fused salt heat storage system, a CO2 cycle power generation system and a refrigeration cycle system, and the solar fused salt heat storage system is used for storing solar radiation heat and heat converted by off-peak power; according to the CO2 cycle power generation system, CO2 is heated through high-temperature molten salt, and meanwhile the CO2 is condensed into a liquid state through cold energy prepared in the off-peak power period of the system. The system can also adjust the CO2 flow through the CO2 liquid storage tank, and is used for variable load operation of the system. The refrigeration cycle system produces cooling capacity in the electric power trough period, CO2 can be condensed and cooled, and if residual cooling capacity exists, the refrigeration cycle system can also be used for building cooling. On the basis of the molten salt heat storage system, electric heating molten salt and electric refrigeration are further adopted to store electric energy so as to increase the temperature difference of the power generation system, then the variable load adjusting range of the CO2 cycle power generation system is widened, and the power generation efficiency of the system is improved.

Description

Technical Field

[0001] The present invention belongs to the field of new energy technology, and in particular relates to a CO2 cycle power generation system and method coupled with solar molten salt heat storage and electrical energy storage. Background Art

[0002] Solar thermal power generation is a new energy utilization technology. It collects solar thermal energy through a large-scale array of parabolic or dish-shaped mirrors, and then generates steam through a heat exchange device to drive a steam turbine generator to generate electricity. Its advantage is that it can achieve stable power output and is suitable as a basic power and peak-shaving power source. At present, solar thermal power generation uses molten salt heat storage to reduce the impact of solar energy instability and increase the operating time of the power generation system. Molten salt heat storage technology is an advanced thermal energy storage system that uses molten salt as a heat storage medium. Its core principle is to store thermal energy in a high-temperature molten salt solution to achieve the required operating temperature and chemical stability. As a new power generation system with high efficiency and good compactness, the CO2 power cycle has received widespread attention from academia and industry, and can complete the efficient conversion of solar thermal energy to electrical energy. CO2 power cycle technology is a new type of thermal cycle system that uses supercritical CO2 as a working fluid. The characteristic of this technology is that no phase change occurs during the cycle heating and cooling stages, so a higher thermoelectric conversion efficiency can be achieved. Carbon dioxide has good thermodynamic properties as a working fluid, making it more efficient in transferring heat energy and doing work. Existing technologies are all based on coupling solar molten salt heat storage with supercritical CO2 power cycle to complete the conversion of light, heat and electricity. In the existing solar molten salt heat storage power generation system, molten salt can only store unstable heat from solar energy and cannot participate in the peak load regulation of the power grid. At the same time, although the supercritical CO2 cycle power generation system used can operate with variable load, the load regulation range is limited and it is difficult to meet the peak load regulation needs of the power grid. Summary of the invention

[0003] To solve the above problems, the present invention provides a CO2 cycle power generation system and method coupled with solar molten salt heat storage and electrical energy storage, so as to solve the problem that in the existing solar molten salt heat storage power generation system, the molten salt can only store unstable heat from solar energy and cannot participate in the peak regulation of the power grid. At the same time, the load regulation range of the power generation system used is limited, and it is difficult to meet the peak regulation needs of the power grid.

[0004] In one aspect, the present invention provides a CO2 cycle power generation system coupled with solar molten salt heat storage and electrical energy storage, comprising:

[0005] A solar molten salt heat storage system, the solar molten salt heat storage system comprises a heat absorber, a molten salt hot tank, a heater, a first molten salt pump, a molten salt cold tank and a second molten salt pump connected in a clockwise closed loop, wherein an electric heating rod is arranged inside the molten salt hot tank, and both ends of the electric heating rod are connected to a power source;

[0006] A CO2 cycle power generation system, wherein the CO2 cycle power generation system is connected to the solar molten salt heat storage system through a heater, and the CO2 cycle power generation system comprises a heater, a turbine, a high-temperature regenerator, a low-temperature regenerator, a first cooler, a CO2 liquid storage tank, a first condenser and a CO2 pump, wherein the heater, the turbine and the high-temperature regenerator are connected in a clockwise closed loop, the high-temperature regenerator is connected to the low-temperature regenerator, and the low-temperature regenerator, the first cooler, the CO2 liquid storage tank, the first condenser and the CO2 pump are connected in a clockwise closed loop;

[0007] A refrigeration cycle system, the refrigeration cycle system includes a first condenser, a normal temperature water tank, a second water pump, an evaporator, a low temperature water tank and a third water pump, the first condenser, the normal temperature water tank, the second water pump, the evaporator, the low temperature water tank and the third water pump are connected in a clockwise closed loop, wherein a second condenser is arranged on one side of the first condenser, the second condenser is connected in parallel with the first condenser, a second compressor and a second cooler are arranged on the cold fluid side of the evaporator, and the evaporator, the second compressor and the second cooler are connected in a clockwise closed loop.

[0008] According to a specific embodiment of the present invention, in a solar molten salt heat storage system, a heat absorber is connected to a molten salt hot tank through a valve C1, the molten salt hot tank is connected to a heater through a valve C2, a cold fluid side of the heater is connected to a first molten salt pump through a valve C6, the first molten salt pump is connected to a molten salt cold tank, the molten salt cold tank is connected to a second molten salt pump through a valve C7, and the second molten salt pump is connected to the heat absorber through a valve C8.

[0009] According to a specific embodiment of the present invention, in a CO2 cycle power generation system, the hot fluid side of the heater is connected to the turbine through a valve C3, the turbine is connected to the high-temperature regenerator through a valve C4, the high-temperature regenerator is connected to the low-temperature regenerator through a valve C9, the low-temperature regenerator is connected to the first cooler through a valve C14, the first cooler is connected to the CO2 liquid storage tank through a throttle valve C17, the CO2 liquid storage tank is connected to the first condenser through a valve C20, the first condenser is connected to the CO2 pump through a valve C23, the CO2 pump is connected to the low-temperature regenerator through a valve C13, the low-temperature regenerator is connected to the high-temperature regenerator through a valve C10, and the high-temperature regenerator is connected to the heater through a valve C5.

[0010] According to a specific embodiment of the present invention, a re-compressor is further provided at the hot fluid side outlet of the low-temperature regenerator, the input end of the re-compressor is connected to the low-temperature regenerator through a valve C12, and the output end of the re-compressor is connected to the high-temperature regenerator through a valve C11.

[0011] According to a specific embodiment of the present invention, a cooling tower and a first water pump are also provided on one side of the first cooler, the input end of the cooling tower is connected to the first cooler through a valve C15, the output end of the cooling tower is connected to the first water pump, and the first water pump is connected to the first cooler through a valve C16.

[0012] According to a specific embodiment of the present invention, a first compressor is further provided at the output end of the first cooler, the input end of the first compressor is connected to the first cooler through a valve C21, and the output end of the first compressor is connected to the low-temperature regenerator through a valve C22.

[0013] According to a specific embodiment of the present invention, the output end of the CO2 storage tank is also connected to the input end of the CO2 pump through a valve C19.

[0014] According to a specific embodiment of the present invention, the output end of the first cooler is also connected to the input end of the first condenser through a valve C18.

[0015] According to a specific embodiment of the present invention, in a refrigeration cycle system, an input end of a normal temperature water tank is connected to a first condenser through a valve C24, an output end of the normal temperature water tank is connected to a second water pump through a valve C25, the second water pump is connected to an evaporator through a valve C26, the evaporator is connected to a low temperature water tank through a valve C27, the low temperature water tank is connected to a third water pump through a valve C28, one side of the third water pump is connected in two ways, one way is connected to the second condenser through a valve C29, and the other way is connected to the first condenser through a valve C30, the second condenser is connected to the first condenser through a valve C31, the evaporator is connected to a second compressor through a valve C32, the second compressor is connected to a second cooler through a valve C33, and the second cooler is connected to the evaporator through a valve C34.

[0016] In one aspect, the present invention provides a CO2 cycle power generation method coupled with solar molten salt heat storage and electric energy storage, the method is based on the above-mentioned CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage, comprising:

[0017] Peak power generation regulation mode: In the peak power generation regulation mode, the solar molten salt heat storage system, the CO2 cycle power generation system and the refrigeration cycle system operate jointly. The solar molten salt heat storage system uses the absorbed solar radiation heat and the heat stored during the power off period to drive the CO2 cycle power generation system to operate in a transcritical state. At the same time, the refrigeration cycle system uses the stored cold to further condense and cool the CO2. If there is any residual cold in the refrigeration cycle, it is used for building cooling.

[0018] In the power off-peak heat and cold storage mode, the solar molten salt heat storage system and the refrigeration cycle system operate jointly, and the CO2 cycle power generation system is on standby. The solar molten salt heat storage system is used to store the absorbed solar radiation heat and use the low-cost electricity from the grid to heat the molten salt. At the same time, the refrigeration cycle system is used to produce and store cold energy;

[0019] Electricity parity power generation regulation mode. Under the electricity parity power generation regulation mode, the solar molten salt heat storage system, the CO2 cycle power generation system and the refrigeration cycle system operate jointly. The solar molten salt heat storage system is used to store the absorbed solar radiation heat and drive the CO2 cycle power generation system to operate in a supercritical state. If there is any surplus cold stored during the power off period, it will be used for building cooling.

[0020] According to a specific embodiment of the present invention, in the peak power generation regulation mode, the solar molten salt thermal storage system first uses the solar radiation heat stored in the molten salt hot tank and the heat stored by electrically heating the molten salt during the power off period to exchange heat with CO2 in the heater, thereby driving the CO2 cycle power generation system to operate in a transcritical state, and at the same time, the high-temperature molten salt after the heat exchange is pressurized and stored in the molten salt cold tank. The CO2 cycle power generation system uses the heater to heat CO2, drives the turbine to generate power, and uses the cold stored in the system to condense CO2 into a liquid state. The refrigeration cycle system uses the cold stored during the power off period to condense and cool the CO2 and store it in a normal temperature water tank. If there is residual cold in the refrigeration cycle system during the refrigeration cycle, the residual cold in the refrigeration cycle will be cooled through the second condenser for building cooling.

[0021] According to a specific embodiment of the present invention, the method further includes:

[0022] In the peak power generation regulation mode, the flow of CO2 in the system is regulated by the CO2 storage tank for variable load operation of the system.

[0023] According to a specific embodiment of the present invention, in the power off-peak heat storage and cold storage mode, the solar molten salt heat storage system first uses the low-temperature molten salt in the molten salt cold tank to absorb solar radiation heat, and stores the high-temperature molten salt after heat absorption in the molten salt hot tank, and at the same time connects the electric heating rod to use the low-cost electricity from the power grid to heat the molten salt in the molten salt hot tank; the refrigeration cycle system allows the water in the normal temperature water tank to flow through the evaporator to release heat and cool the refrigerant in the refrigeration system, and stores it in the low-temperature water tank, and consumes the low-cost electricity of the system to compress the refrigerant at the outlet of the evaporator through the second compressor to heat it up, then flows through the second cooler to cool it down, and finally flows back to the evaporator.

[0024] According to a specific embodiment of the present invention, in the power parity power generation regulation mode, the solar molten salt thermal storage system first uses the low-temperature molten salt in the molten salt cold tank to absorb solar radiation heat, and stores the high-temperature molten salt after heat absorption in the molten salt hot tank, driving the CO2 cycle power generation system to operate in a supercritical state; at the same time, the high-temperature molten salt after heat exchange is pressurized and stored in the molten salt cold tank; the CO2 cycle power generation system uses a heater to heat CO2, drives the turbine to generate power, and uses the first cooler to cool the CO2 in the system. When the power load is high, the flow of CO2 in the system is increased by releasing the CO2 in the CO2 storage tank to increase the power generation of the system; when the power load is low, the cooled CO2 is stored in the CO2 storage tank through the throttle valve, reducing the flow of CO2 in the system to reduce the power generation of the system.

[0025] According to a specific embodiment of the present invention, the method further includes:

[0026] In the electricity parity power generation regulation mode, if there is surplus cooling capacity in the refrigeration cycle system, the cold water in the low-temperature water tank is released and cooled through the second condenser to provide cooling to the load side.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] The present invention provides a CO2 cycle power generation system and method that couples solar molten salt heat storage and electric energy storage. On the basis of the molten salt heat storage system, the system further adopts electric heating of molten salt and electric refrigeration to store electric energy to increase the temperature difference of the power generation system, thereby improving the variable load regulation range of the CO2 cycle power generation system. In addition, during peak power consumption periods, the system drives the CO2 power generation system to operate transcritically by heating high-temperature molten salt to increase the system's power generation load and efficiency. During low power consumption periods, the system can achieve large-scale storage of electricity based on heat storage and cold storage. At the same time, when the load side needs cooling, the stored cold can also be used to achieve centralized cooling on the load side. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 It is a structural block diagram of a CO2 cycle power generation system coupled with solar molten salt heat storage and electrical energy storage according to one embodiment of the present invention.

[0031] Reference numerals:

[0032] 1-heliostat field; 2-heat absorber; 3-molten salt hot tank; 4-electric heating rod; 5-power supply; 6-heat absorption tower; 7-second molten salt pump; 8-first molten salt pump; 9-molten salt cold tank; 10-heater; 11-turbine; 12-high temperature regenerator; 13-low temperature regenerator; 14-recompressor; 15-cooling tower; 16-first water pump; 17-first cooler; 18-first compressor; 19-CO2 pump; 20-first condenser; 21-CO2 storage tank; 22-normal temperature water tank; 23-second water pump; 24-evaporator; 25-low temperature water tank; 26-third water pump; 27-second compressor; 28-second cooler; 29-second condenser. DETAILED DESCRIPTION

[0033] In order to make those skilled in the art understand the concept and thought of the present invention more clearly, the present invention is described in detail below in conjunction with specific embodiment.It should be understood that the embodiment provided herein is only a part of all embodiments that the present invention may have.Those skilled in the art, after reading the specification of the application, have the ability to make improvements, transformations, or replacements to part or the whole of the following embodiments, and these improvements, transformations, or replacements are also included in the scope of the present invention.

[0034] In this article, the terms "first", "second" and other similar words are not intended to imply any order, quantity and importance, but are only used to distinguish different elements. In this article, the terms "one", "an" and other similar words are not intended to indicate that there is only one thing, but to indicate that the relevant description is only for one of the things, and the thing may have one or more. In this article, the terms "comprise", "include" and other similar words are intended to indicate logical mutual relations, and cannot be regarded as indicating spatial structural relations. For example, "A includes B" is intended to indicate that B belongs to A logically, but does not mean that B is located inside A in space. In addition, the meanings of the terms "comprise", "include" and other similar words should be regarded as open, rather than closed. For example, "A includes B" is intended to indicate that B belongs to A, but B does not necessarily constitute the whole of A, and A may also include other elements such as C, D, and E.

[0035] In this document, the terms "embodiment", "this embodiment", "one embodiment", and "an embodiment" do not mean that the relevant description is only applicable to a specific embodiment, but rather that the description may also be applicable to one or more other embodiments. Those skilled in the art should understand that in this document, any description of a certain embodiment can be replaced, combined, or combined in other ways with the relevant descriptions in one or more other embodiments, and the new embodiments generated by the replacement, combination, or combination in other ways are easily conceivable by those skilled in the art and fall within the scope of protection of the present invention.

[0036] Example 1

[0037] Additional aspects and advantages of embodiments of the present invention will be described in part in the following description, and will become apparent from the following description, or will be learned through practice of embodiments of the present invention. Figure 1 The embodiment of the present invention provides a CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage, comprising:

[0038] A solar molten salt heat storage system, the solar molten salt heat storage system includes a heat absorber 2, a molten salt hot tank 3, a heater 10, a first molten salt pump 8, a molten salt cold tank 9 and a second molten salt pump 7, the outlet of the heat absorber 2 is connected to the inlet of the molten salt hot tank 3 through a valve C1, the outlet of the molten salt hot tank 3 is connected to the cold fluid side inlet of the heater 10 through a valve C2, the cold fluid side outlet of the heater 10 is connected to the inlet of the first molten salt pump 8 through a valve C6, the outlet of the first molten salt pump 8 is connected to the inlet of the molten salt cold tank 9, the outlet of the molten salt cold tank 9 is connected to the inlet of the second molten salt pump 7 through a valve C7, and the outlet of the second molten salt pump 7 is connected to the inlet of the heat absorber 2 through a valve C8.

[0039] In a specific embodiment of the present invention, an electric heating rod 4 is provided inside the molten salt hot tank 3, and both ends of the electric heating rod 4 are connected to a power supply 5. The electric heating rod 4 is powered by the power supply 5. By providing the electric heating rod 4, the high-temperature molten salt in the molten salt hot tank 3 is further heated and the heated high-temperature molten salt can drive the CO2 cycle power generation system to operate in a transcritical state.

[0040] In a specific embodiment of the present invention, the solar molten salt heat storage system further includes a heat absorption tower 6 , and the top of the heat absorption tower 6 is used for fixing and installing the heat absorber 2 .

[0041] The CO2 cycle power generation system includes a turbine 11, a high-temperature regenerator 12, a low-temperature regenerator 13, a recompressor 14, a first cooler 17, a cooling tower 15, a first water pump 16, a first compressor 18, a CO2 liquid storage tank 21, a first condenser 20 and a CO2 pump 19. The inlet of the turbine 11 is connected to the hot fluid side outlet of the heater 10 through a valve C3, the outlet of the turbine 11 is connected to the hot fluid side inlet of the high-temperature regenerator 12 through a valve C4, and the hot fluid side outlet of the high-temperature regenerator 12 is connected to the low-temperature regenerator 12 through a valve C9. The hot fluid side inlet of the high temperature regenerator 13 is connected, and the hot fluid side outlet of the low temperature regenerator 13 is connected in two ways, one way is connected to the inlet of the recompressor 14 through the valve C12, and the outlet of the recompressor 14 is connected to the cold fluid side inlet of the high temperature regenerator 12 through the valve C11, and the other way is connected to the cold fluid side inlet of the first cooler 17 through the valve C14. The cold fluid side outlet of the first cooler 17 is connected in three ways, the first way is connected to the inlet of the first compressor 18 through the valve C21, and the outlet of the first compressor 18 is connected to the low temperature regenerator 12 through the valve C22. The cold fluid side inlet of the regenerator 13 is connected; the second path is connected to the inlet of the CO2 liquid storage tank 21 through the throttle valve C17, the outlet of the CO2 liquid storage tank 21 is connected to the hot fluid side inlet of the first condenser 20 through the valve C20, the outlet of the CO2 liquid storage tank 21 is also connected to the inlet of the CO2 pump 19 through the valve C19, the hot fluid side outlet of the first condenser 20 is connected to the inlet of the CO2 pump 19 through the valve C23, and the outlet of the CO2 pump 19 is connected to the cold fluid side inlet of the low-temperature regenerator 13 through the valve C13; the third path is connected to the inlet of the CO2 liquid storage tank 21 through the valve C18 is connected to the hot fluid side inlet of the first condenser 20; the cold fluid side outlet of the low-temperature regenerator 13 is connected to the cold fluid side inlet of the high-temperature regenerator 12 through valve C10, and the cold fluid side outlet of the high-temperature regenerator 12 is connected to the hot fluid side inlet of the heater 10 through valve C5; the hot fluid side outlet of the first cooler 17 is connected to the inlet of the cooling tower 15 through valve C15, and the outlet of the cooling tower 15 is connected to the inlet of the first water pump 16, and the outlet of the first water pump 16 is connected to the hot fluid side inlet of the first cooler 17 through valve C16.

[0042] The refrigeration cycle system includes a first condenser 20, a normal temperature water tank 22, a second water pump 23, an evaporator 24, a low temperature water tank 25, a third water pump 26, a second condenser 29, a second compressor 27 and a second cooler 28. The inlet of the normal temperature water tank 22 is connected to the hot fluid side outlet of the first condenser 20 through a valve C24, the outlet of the normal temperature water tank 22 is connected to the inlet of the second water pump 23 through a valve C25, the outlet of the second water pump 23 is connected to the hot fluid side inlet of the evaporator 24 through a valve C26, the hot fluid side outlet of the evaporator 24 is connected to the inlet of the low temperature water tank 25 through a valve C27, and the outlet of the low temperature water tank 25 is connected to the inlet of the low temperature water tank 25 through a valve C28. Valve C28 is connected to the inlet of the third water pump 26, and the outlet of the third water pump 26 is connected in two ways, one way is connected to the cold fluid side inlet of the second condenser 29 through valve C29, and the cold fluid side outlet of the second condenser 29 is connected to the hot fluid side outlet of the first condenser 20 through valve C31, and the other way is connected to the hot fluid side inlet of the first condenser 20 through valve C30; the cold fluid side outlet of the evaporator 24 is connected to the inlet of the second compressor 27 through valve C32, the outlet of the second compressor 27 is connected to the inlet of the second cooler 28 through valve C33, and the outlet of the second cooler 28 is connected to the inlet of the evaporator 24 through valve C34.

[0043] In a specific embodiment of the present invention, the system further includes a heliostat field 1 , which is disposed on one side of the heat absorption tower 6 and is used to reflect sunlight onto the heat absorber 2 on the top of the heat absorption tower 6 .

[0044] The embodiment of the present invention provides a CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage, and the solar molten salt heat storage system is used to store the absorbed solar radiation heat. The CO2 cycle power generation system uses the high-temperature molten salt in the solar molten salt heat storage system to heat CO2 to drive the CO2 cycle power generation system to operate in a transcritical state, thereby improving the system efficiency. At the same time, the CO2 is condensed into a liquid state using the cold stored in the system. The system can also adjust the flow of CO2 in the system through the CO2 liquid storage tank 21 for system variable load operation. The refrigeration cycle system uses the cold stored during the power trough period to cool down the CO2 condensation and store it in a normal temperature water tank 22. If there is any residual cold in the refrigeration cycle process, the refrigeration cycle system can be used for building cooling. During the heat storage process of the system, the solar molten salt heat storage system is heated by the solar radiation energy through the low-temperature molten salt in the molten salt cold tank 9, and the heated high-temperature molten salt flows into the molten salt hot tank 3, and the energy is stored in the form of high-temperature molten salt. During the period of low electricity, on the one hand, the temperature of the molten salt in the molten salt hot tank 3 can be further increased by electric heating through the solar molten salt heat storage system, and on the other hand, the refrigeration cycle can be driven by electricity to generate cold and store it in cold water. During the peak electricity stage, the CO2 in the solar molten salt heat storage system is condensed to a liquid state through the stored cold, and the system operates in a transcritical state. In addition, the stored cold can also be used for external cooling. In the electricity parity stage, the CO2 cycle power generation system is in a supercritical state, and the system adjusts the flow of CO2 in the system through the CO2 storage tank 21, thereby achieving variable load operation.

[0045] Example 2

[0046] Based on the above system, an embodiment of the present invention further provides a solar molten salt heat storage, electrical energy storage and CO2 cycle coupled power generation method, comprising:

[0047] In the peak power generation regulation mode, the solar molten salt heat storage system, the CO2 cycle power generation system and the refrigeration cycle system operate jointly. The solar molten salt heat storage system uses the absorbed solar radiation heat and the heat stored during the power off period to drive the CO2 cycle power generation system to operate in a transcritical state. At the same time, the refrigeration cycle system uses the stored cold to further condense and cool the CO2. If there is any surplus cold during the refrigeration cycle, it will be used for building cooling.

[0048] Heat and cold storage mode during power outages. In the heat and cold storage mode during power outages, the solar molten salt heat storage system and the refrigeration cycle system operate jointly, and the CO2 cycle power generation system is on standby. The solar molten salt heat storage system first stores the absorbed solar radiation heat, and uses the low-cost electricity from the power grid to heat the molten salt to increase the temperature of the molten salt. At the same time, cold energy is produced and stored through the refrigeration cycle system.

[0049] Electricity parity power generation regulation mode. Under the electricity parity power generation regulation mode, the solar molten salt heat storage system, the CO2 cycle power generation system and the refrigeration cycle system operate jointly. The solar molten salt heat storage system first stores the absorbed solar radiation heat and drives the CO2 cycle power generation system to operate in a supercritical state. If there is any surplus cold stored during the power off period, it will be used for building cooling.

[0050] Specifically, in the peak power generation regulation mode, the solar molten salt heat storage system first uses the solar radiation heat stored in the molten salt hot tank 3 and the heat stored by electrically heating the molten salt during the power off period to exchange heat with CO2 in the heater 10, thereby driving the CO2 cycle power generation system to operate in a transcritical state. At the same time, the high-temperature molten salt after heat exchange is pressurized and stored in the low-temperature molten salt cold tank 9. The CO2 cycle power generation system uses the heater 10 to heat CO2, drives the turbine 11 to generate power, and uses the cold stored in the system to condense CO2 into a liquid state. The refrigeration cycle system uses the cold stored during the power off period to condense and cool CO2 and store it in the normal temperature water tank 22. If there is residual cold in the refrigeration cycle system during the refrigeration cycle, the residual cold in the refrigeration cycle will be cooled through the second condenser 29 for building cooling.

[0051] In a specific embodiment of the present invention, during the operation of the system in the peak power generation regulation mode, the solar molten salt heat storage system uses the low-temperature molten salt at the outlet of the molten salt cold tank 9 to absorb the heat of solar radiation and heat up, and then stores it in the molten salt hot tank 3. The high-temperature molten salt at the outlet of the molten salt hot tank 3 exchanges heat with CO2 in the heater 10 and then cools down, and is pressurized and stored in the molten salt cold tank 9 by the first molten salt pump 8. At the same time, the solar molten salt heat storage system drives the CO2 cycle power generation system to operate in a transcritical state, that is, the CO2 in the system absorbs the heat of the high-temperature molten salt in the heater 10 to further heat up, and then drives the turbine 11 to generate power, and the CO2 at the outlet of the turbine 11 releases heat and cools in the high-temperature regenerator 12 and the low-temperature regenerator 13 in turn. The CO2 at the outlet of the hot fluid side of the low-temperature regenerator 13 flows through the recompressor 14 for compression and temperature increase, and finally mixes with the CO2 at the outlet of the cold fluid side of the low-temperature regenerator 13, and further absorbs heat and heats up on the cold fluid side of the high-temperature regenerator 12, and flows through the first cooler 17 for further heat exchange and cooling with cooling water, and the cooling water absorbs the heat of CO2 and flows through the cooling tower 15 for cooling, and finally flows back to the first cooler 17 through the first water pump 16. The CO2 cooled by the first cooler 17 enters the first condenser 20 through the valve C18 and further condenses into liquid. At the same time, in order to increase the power generation of the system, the CO2 flow in the system can be increased by releasing CO2 through the CO2 storage tank 21. That is, the CO2 at the outlet of the CO2 storage tank 21 is mixed with the CO2 at the outlet of the valve C18, and then further condensed and cooled in the first condenser 20, and then flows to the cold fluid side of the low-temperature regenerator 13 through the CO2 pump 19. In the refrigeration cycle, the refrigeration cycle system uses the cold energy stored during the power off period to further condense and cool the CO2. That is, the cooling water at the outlet of the low-temperature water tank 25 is pressurized by the third water pump 26 and flows through the first condenser 20 to further cool the CO2 and finally store it in the normal temperature water tank 22.

[0052] Optionally, in the peak power generation regulation mode, the flow of CO2 in the system is regulated by the CO2 storage tank 14, thereby achieving variable load operation of the system.

[0053] Optionally, if there is surplus cooling capacity in the refrigeration cycle system during the refrigeration cycle, the cold water in the low-temperature water tank 25 can be further cooled and lowered through the second condenser 29 for use in cooling the building.

[0054] Specifically, in the low-power heat storage and cold storage mode, the solar molten salt heat storage system first uses the low-temperature molten salt in the molten salt cold tank 9 to absorb solar radiation heat, and stores the high-temperature molten salt after heat absorption in the molten salt hot tank 3. At the same time, the electric heating rod 4 is connected to use the low-cost power of the power grid to heat the molten salt in the molten salt hot tank 3 to increase the temperature of the molten salt. The refrigeration cycle system releases heat and cools the water in the normal temperature water tank 22 through the evaporator 24 to the refrigerant in the refrigeration system, and stores it in the low-temperature water tank 25. The refrigerant at the outlet of the evaporator 24 is compressed and heated by the second compressor 27 by consuming the low-cost power of the system, and then flows through the second cooler 28 to cool and cool, and finally flows back to the evaporator 24. The system can store heat and cold at the same time, and can realize large-scale storage of electricity. Not only can it realize the efficient conversion of solar thermal electricity, but it can also store low-cost electricity on a large scale.

[0055] In a specific embodiment of the present invention, during the operation of the power valley heat storage and cold storage mode, the solar molten salt heat storage system uses the low-temperature molten salt at the outlet of the molten salt cold tank 9 to absorb the heat of solar radiation and heat up, and then stores it in the molten salt hot tank 3. The high-temperature molten salt at the outlet of the molten salt hot tank 3 is cooled and cooled after heat exchange with CO2 in the heater 10, and is pressurized and stored in the molten salt cold tank 9 by the first molten salt pump 8. At the same time, by connecting the electric heating rod 4 to consume low-cost electricity to heat the molten salt in the molten salt hot tank 3, the temperature of the molten salt is further increased, and then the temperature of the stored heat is increased. In this mode, the CO2 power generation system is in a shutdown state. During the refrigeration cycle of the refrigeration cycle system, the water at the outlet of the normal temperature water tank 22 flows through the evaporator 24 through the second water pump 23, releases heat to the refrigerant in the refrigeration system and cools it, and is stored in the low-temperature water tank 25. By consuming low-cost electricity, the refrigerant at the outlet of the evaporator 24 is compressed and heated by the second compressor 27, cooled and cooled by the second cooler 28, and finally flows back to the evaporator 24.

[0056] Specifically, in the power parity power generation regulation mode, the solar molten salt heat storage system first uses the low-temperature molten salt in the molten salt cold tank 9 to absorb solar radiation heat, and stores the high-temperature molten salt after heat absorption in the molten salt hot tank 3, driving the CO2 cycle power generation system to operate in a supercritical state, and at the same time pressurizing and storing the high-temperature molten salt after heat exchange in the molten salt cold tank 9; the CO2 cycle power generation system uses the heater 10 to heat CO2, drives the turbine 11 to generate power, and uses the first cooler 17 to cool the CO2 in the system. When the power load is high, the flow of CO2 in the system is increased by releasing the CO2 in the CO2 storage tank 21 to increase the power generation of the system; when the power load is low, the cooled CO2 is stored in the CO2 storage tank through the throttle valve C17, reducing the flow of CO2 in the system to reduce the power generation of the system.

[0057] Optionally, in the electricity parity power generation regulation mode, if there is surplus cooling capacity in the refrigeration cycle system during the refrigeration cycle, the cold water in the low-temperature water tank 25 is released and cooled through the second condenser 29 to provide cooling to the load side.

[0058] In a specific embodiment of the present invention, the solar molten salt heat storage system operates normally and drives the CO2 cycle power generation system to operate in a supercritical state, that is, the CO2 in the system absorbs the heat of the high-temperature molten salt in the heater 10 to further heat up, and then drives the turbine 11 to generate power, and the CO2 at the outlet of the turbine 11 releases heat and cools in the high-temperature regenerator 12 and the low-temperature regenerator 13 in turn. The CO2 at the outlet of the low-temperature regenerator 13 flows through the first cooler 17 to further exchange heat with the cooling water and cool down, and then is compressed and heated in the first compressor 18 and flows back to the cold fluid side of the low-temperature regenerator 13. The cooling water of the first cooler 17 flows through the cooling tower 15 to cool down after absorbing the heat of CO2, and finally flows back to the first cooler 17 through the first water pump 16; the other way flows to the re-compressor 14 for further compression and temperature increase, and finally mixes with the CO2 at the outlet of the cold fluid side of the low-temperature regenerator 13 and further heats up on the cold fluid side of the high-temperature regenerator 12. When the power load of the system is high, the flow rate of CO2 in the system is increased through the CO2 storage tank 21, that is, the CO2 at the outlet of the CO2 storage tank 21 flows through the CO2 pump 19 through the valve C19, and flows through the cold fluid side of the low-temperature regenerator 13 after being pressurized by the CO2 pump 19. When the power load of the system is low, a part of the CO2 cooled by the first cooler 17 is stored in the CO2 storage tank 21 after passing through the throttle valve 17 to reduce the system CO2 flow rate. In the refrigeration cycle, when the system has a cooling demand, the cold water in the low-temperature water tank 25 can be released, and after further cooling and cooling by the second condenser 29, it can be used for building cooling.

[0059] In summary, the CO2 cycle power generation system and method coupled with solar molten salt heat storage and electrical energy storage provided by the present invention has the following advantages:

[0060] Based on the molten salt heat storage system, the present invention further adopts electric heating of molten salt and electric refrigeration to store electric energy to increase the temperature difference of the power generation system, thereby improving the variable load regulation range of the CO2 cycle power generation system. In addition, during peak power consumption periods, the system drives the CO2 power generation system to transcritical operation by heating high-temperature molten salt to increase the system's power generation load and efficiency; during low power consumption periods, the system can achieve large-scale storage of electricity based on heat storage and cold storage. At the same time, when the load side needs cooling, the stored cold can also be used to achieve centralized cooling on the load side.

[0061] The above describes in detail the concepts, principles and ideas of the present invention in conjunction with specific implementation methods (including embodiments and examples). Those skilled in the art should understand that the implementation methods of the present invention are not limited to the forms given above. After reading this application document, those skilled in the art can make any possible improvements, substitutions and equivalent forms to the steps, methods, systems and components in the above implementation methods. These improvements, substitutions and equivalent forms should be deemed to fall within the scope of the present invention, and the protection scope of the present invention is subject only to the claims.

Claims

1. A CO2 cycle power generation system coupled with solar molten salt heat storage and electrical energy storage, characterized in that: include: A solar molten salt heat storage system, the solar molten salt heat storage system comprising a heat absorber, a molten salt hot tank, a heater, a first molten salt pump, a molten salt cold tank and a second molten salt pump connected in a clockwise closed loop, wherein an electric heating rod is arranged inside the molten salt hot tank, and both ends of the electric heating rod are connected to a power source; A CO2 cycle power generation system, wherein the CO2 cycle power generation system is connected to the solar molten salt heat storage system through the heater, and the CO2 cycle power generation system comprises a heater, a turbine, a high-temperature regenerator, a low-temperature regenerator, a first cooler, a CO2 liquid storage tank, a first condenser and a CO2 pump, wherein the heater, the turbine and the high-temperature regenerator are connected in a clockwise closed loop, the high-temperature regenerator is connected to the low-temperature regenerator, and the low-temperature regenerator, the first cooler, the CO2 liquid storage tank, the first condenser and the CO2 pump are connected in a clockwise closed loop; A refrigeration cycle system, the refrigeration cycle system includes a first condenser, a normal temperature water tank, a second water pump, an evaporator, a low temperature water tank and a third water pump, the first condenser, the normal temperature water tank, the second water pump, the evaporator, the low temperature water tank and the third water pump are connected in a clockwise closed loop, wherein a second condenser is arranged on one side of the first condenser, the second condenser is connected in parallel with the first condenser, a second compressor and a second cooler are arranged on the cold fluid side of the evaporator, and the evaporator, the second compressor and the second cooler are connected in a clockwise closed loop.

2. The CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage according to claim 1 is characterized in that: In the solar molten salt heat storage system, the heat absorber is connected to the molten salt hot tank through valve C1, the molten salt hot tank is connected to the heater through valve C2, the cold fluid side of the heater is connected to the first molten salt pump through valve C6, the first molten salt pump is connected to the molten salt cold tank, the molten salt cold tank is connected to the second molten salt pump through valve C7, and the second molten salt pump is connected to the heat absorber through valve C8.

3. The CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage according to claim 2 is characterized in that: In the CO2 cycle power generation system, the hot fluid side of the heater is connected to the turbine through a valve C3, the turbine is connected to the high-temperature regenerator through a valve C4, the high-temperature regenerator is connected to the low-temperature regenerator through a valve C9, the low-temperature regenerator is connected to the first cooler through a valve C14, the first cooler is connected to the CO2 liquid storage tank through a throttle valve C17, the CO2 liquid storage tank is connected to the first condenser through a valve C20, the first condenser is connected to the CO2 pump through a valve C23, the CO2 pump is connected to the low-temperature regenerator through a valve C13, the low-temperature regenerator is connected to the high-temperature regenerator through a valve C10, and the high-temperature regenerator is connected to the heater through a valve C5.

4. The CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage according to claim 3 is characterized in that: A recompressor is also provided at the hot fluid side outlet of the low-temperature regenerator. The input end of the recompressor is connected to the low-temperature regenerator via a valve C12, and the output end of the recompressor is connected to the high-temperature regenerator via a valve C11.

5. The CO2 cycle power generation system coupled with solar molten salt heat storage and electrical energy storage according to claim 4 is characterized in that: A cooling tower and a first water pump are also provided on one side of the first cooler. The input end of the cooling tower is connected to the first cooler through a valve C15, the output end of the cooling tower is connected to the first water pump, and the first water pump is connected to the first cooler through a valve C16.

6. The CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage according to claim 5 is characterized in that: A first compressor is also provided at the output end of the first cooler, the input end of the first compressor is connected to the first cooler via a valve C21, and the output end of the first compressor is connected to the low-temperature regenerator via a valve C22.

7. The CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage according to claim 6 is characterized in that: The output end of the CO2 storage tank is also connected to the input end of the CO2 pump through a valve C19.

8. The CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage according to claim 7 is characterized in that: The output end of the first cooler is also connected to the input end of the first condenser through a valve C18.

9. The CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage according to claim 8 is characterized in that: In the refrigeration cycle system, the input end of the normal temperature water tank is connected to the first condenser through a valve C24, the output end of the normal temperature water tank is connected to the second water pump through a valve C25, the second water pump is connected to the evaporator through a valve C26, the evaporator is connected to the low temperature water tank through a valve C27, the low temperature water tank is connected to the third water pump through a valve C28, one side of the third water pump is connected in two ways, one way is connected to the second condenser through a valve C29, and the other way is connected to the first condenser through a valve C30, the second condenser is connected to the first condenser through a valve C31, the evaporator is connected to the second compressor through a valve C32, the second compressor is connected to the second cooler through a valve C33, and the second cooler is connected to the evaporator through a valve C34.

10. A CO2 cycle power generation method coupled with solar molten salt heat storage and electric energy storage, the method is based on the CO2 cycle power generation system coupled with solar molten salt heat storage and electric energy storage as claimed in claim 9, characterized in that: The method comprises: The peak power generation regulation mode, in which the solar molten salt heat storage system, the CO2 cycle power generation system and the refrigeration cycle system operate jointly. The solar molten salt heat storage system uses the absorbed solar radiation heat and the heat stored during the power off period to drive the CO2 cycle power generation system to operate in a transcritical state. At the same time, the refrigeration cycle system uses the stored cold to further condense and cool the CO2. If there is any residual cold during the refrigeration cycle, it is used for building cooling; The power-off-peak heat and cold storage mode, in which the solar molten salt heat storage system and the refrigeration cycle system operate jointly, the CO2 cycle power generation system is on standby, the solar molten salt heat storage system is used to store the absorbed solar radiation heat, and use the low-cost electricity from the power grid to heat the molten salt, while the refrigeration cycle system is used to produce and store cold; The electricity parity power generation regulation mode, in which the solar molten salt heat storage system, the CO2 cycle power generation system and the refrigeration cycle system operate jointly. The solar molten salt heat storage system is used to store the absorbed solar radiation heat and drive the CO2 cycle power generation system to operate in a supercritical state. If there is any surplus cold stored during the power off period, it is used for building cooling.

11. The CO2 cycle power generation method coupled with solar molten salt heat storage and electrical energy storage according to claim 10 is characterized in that: In the peak power generation regulation mode, the solar molten salt heat storage system first uses the solar radiation heat stored in the molten salt hot tank and the heat stored by electrically heating the molten salt during the power off period to exchange heat with CO2 in the heater, thereby driving the CO2 cycle power generation system to operate in a transcritical state, and at the same time, the high-temperature molten salt after heat exchange is pressurized and stored in the molten salt cold tank. The CO2 cycle power generation system uses the heater to heat CO2, drives the turbine to do work and generate electricity, and uses the cold stored in the system to condense CO2 into a liquid state. The refrigeration cycle system uses the cold stored during the power off period to condense and cool CO2 and store it in the normal temperature water tank. If there is residual cold in the refrigeration cycle system during the refrigeration cycle, the residual cold in the refrigeration cycle will be cooled through the second condenser for building cooling.

12. The CO2 cycle power generation method coupled with solar molten salt heat storage and electrical energy storage according to claim 11 is characterized in that: The method further comprises: In the power peak generation regulation mode, the flow of CO2 in the system is regulated by the CO2 storage tank for variable load operation of the system.

13. The CO2 cycle power generation method coupled with solar molten salt heat storage and electrical energy storage according to claim 10, characterized in that: In the power-off-peak heat and cold storage mode, the solar molten salt heat storage system first uses the low-temperature molten salt in the molten salt cold tank to absorb solar radiation heat, and stores the high-temperature molten salt after heat absorption in the molten salt hot tank, and at the same time, connects the electric heating rod to heat the molten salt in the molten salt hot tank using the low-cost electricity from the power grid; the refrigeration cycle system allows the water in the normal temperature water tank to flow through the evaporator to release heat and cool the refrigerant in the refrigeration system, and stores it in the low-temperature water tank; the refrigerant at the outlet of the evaporator is compressed and heated by the second compressor by consuming the system's low-cost electricity, and then flows through the second cooler to cool and cool, and finally flows back to the evaporator.

14. The CO2 cycle power generation method coupled with solar molten salt heat storage and electrical energy storage according to claim 10, characterized in that: In the electricity parity power generation regulation mode, the solar molten salt heat storage system first uses the low-temperature molten salt in the molten salt cold tank to absorb solar radiation heat, and stores the high-temperature molten salt after heat absorption in the molten salt hot tank, driving the CO2 circulation power generation system to operate in a supercritical state; at the same time, the high-temperature molten salt after heat exchange is stored in the molten salt cold tank; the CO2 circulation power generation system uses the heater to heat CO2, drives the turbine to do work and generate electricity, and uses the first cooler to cool the CO2 in the system; when the power load is high, the flow rate of CO2 in the system is increased by releasing the CO2 in the CO2 storage tank to increase the power generation of the system; when the power load is low, the cooled CO2 is stored in the CO2 storage tank through the throttle valve, reducing the flow rate of CO2 in the system to reduce the power generation of the system.

15. The CO2 cycle power generation method coupled with solar molten salt heat storage and electrical energy storage according to claim 14, characterized in that: The method further comprises: In the power parity power generation regulation mode, if the refrigeration cycle system has surplus cooling capacity, the cold water in the low-temperature water tank is released and cooled through the second condenser to provide cooling to the load side.

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