Cooling, heating and power energy storage combined supply system based on liquid carbon dioxide circulation

Abstract

The invention discloses a combined cooling, heating and power energy storage system based on liquid carbon dioxide circulation. The combined cooling, heating and power energy storage system comprises a wind / light power generation system, an energy storage system, an energy release system, a heat storage and heat supply system and a cold storage and cold supply system. The wind / light power generation system is connected with the energy storage system through the driving motor, and the energy storage system is connected with the heat storage and supply system through the first heat exchanger. The energy release system is connected with the energy storage system through a second carbon dioxide liquid storage tank; the energy release system is connected with the heat storage and supply system through the second heat exchanger. The cold storage and supply system is connected with the energy storage system through a first cold supply heat exchanger and connected with the energy release system through a second cold supply heat exchanger. Carbon dioxide serves as an energy storage working medium, surplus new energy power of a power grid is stored based on liquid phase storage of the carbon dioxide, meanwhile, by optimizing utilization of cold / heat loads in the energy storage and release process, the requirements for cold supply, heat supply and the like of a user side can be met while power storage is met, and a meaningful thought can be provided for construction and development of a regional micro-grid.

Description

Technical Field

[0001] The present invention belongs to the technical field of microgrid energy storage and combined cooling, heating and power supply, and specifically relates to a combined cooling, heating and power energy storage system based on liquid carbon dioxide circulation. Technical Background

[0002] Microgrid refers to a small power generation and distribution system composed of distributed power systems, energy storage equipment, energy conversion equipment, and related load monitoring and protection equipment. It is an autonomous system that can achieve automatic control, management and protection. It can be connected to the external power grid or run independently. It is an important part of the smart grid. With the increasing severity of energy shortages and environmental pollution, microgrids are being piloted in many regions, and energy storage technology is gradually becoming a key technology for the development of distributed energy.

[0003] Existing energy storage technologies can be mainly divided into mechanical energy storage, electrochemical energy storage, electromagnetic energy storage, etc. according to the energy storage method. Among them, mechanical energy storage technologies include pumped storage technology, compressed air energy storage technology, flywheel energy storage technology, etc.; but due to the limitations of current technical level and implementation conditions, the only technologies that can achieve large-scale energy storage are pumped storage technology and compressed air energy storage technology.

[0004] However, both pumped storage technology and compressed air energy storage technology have certain limitations in their implementation; among them, pumped storage technology requires extremely strict geographical conditions, and compressed air energy storage technology requires a huge gas storage space. The liquefied air energy storage system studied by some scholars has high requirements for liquid storage materials due to the extremely low storage temperature, and it is currently difficult to achieve large-scale application.

[0005] In the distributed energy area, in addition to the demand for electricity load, users also need centralized cooling and heating for daily life. Since the construction of external long-distance transmission pipelines requires large investment and high cost, it is of great application value to develop a multi-form energy supply technology in the community microgrid mode that can store electricity, cold and heat. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a liquid carbon dioxide circulating cold, heat and electricity energy storage and supply system in view of the deficiencies in the above-mentioned prior art, which can absorb abundant new energy electricity such as wind energy and solar energy in the storage area microgrid, and utilize the energy ladder characteristics of the energy storage system itself to realize heat and cold storage, so as to meet the user's cold and heat load requirements.

[0007] The present invention adopts the following technical solutions:

[0008] A cold, heat and electricity energy storage and supply system based on the circulation of liquid carbon dioxide comprises a No. 1 carbon dioxide storage tank, the outlet side of the No. 1 carbon dioxide storage tank is connected to the inlet side of the No. 1 carbon dioxide storage tank via a regenerative heat exchanger, an energy storage system, a No. 2 carbon dioxide storage tank, an energy release system and a regenerative heat exchanger in sequence to form a loop, the energy storage system is connected to a wind / solar power generation system via a driving motor to achieve energy storage and energy release; the energy storage system is connected to a heat storage and heat supply system via a No. 1 heat exchanger, the heat storage system is connected to the heat storage and heat supply system, and the heat storage and heat supply system is connected to the energy release system via a No. 2 heat exchanger to achieve heat storage and heat supply; the energy storage system is connected to the cold storage and cold supply system via a No. 1 cold supply heat exchanger, and the energy release system is connected to the cold storage and cold supply system via a No. 2 cold supply heat exchanger to achieve cold storage and cold supply.

[0009] Specifically, the energy storage system includes a carbon dioxide compressor. The regenerative heat exchanger is connected to the inlet of the carbon dioxide compressor via an electric three-way regulating valve. The outlet of the carbon dioxide compressor is connected to the gas-liquid separator via the No. 1 heat exchanger and the low-temperature expander. The outlet of the gas-liquid separator is divided into two paths, one path is connected to the electric three-way regulating valve via the No. 1 cooling heat exchanger, and the other path is connected to the energy release system via the No. 2 carbon dioxide storage tank.

[0010] Furthermore, the low-temperature expander is connected to the wind / solar power generation system via the No. 1 generator, and the carbon dioxide compressor is connected to the wind / solar power generation system via the electric motor.

[0011] Furthermore, a No. 1 valve is provided between the gas-liquid separator and the No. 2 carbon dioxide storage tank.

[0012] Specifically, the wind / solar power generation system is connected to the carbon dioxide compressor of the energy storage system through an electric motor, and the wind / solar power generation system is connected to the No. 1 generator of the energy storage system and the No. 2 generator of the energy release system through electric load users.

[0013] Specifically, the energy release system includes a turbine, the outlet of the turbine is connected to the regenerative heat exchanger, and the inlet of the turbine is connected to the outlet side of the No. 2 carbon dioxide storage tank via the No. 2 heat exchanger, the No. 2 cooling heat exchanger and the booster pump in sequence.

[0014] Furthermore, a No. 2 valve is provided between the booster pump and the No. 2 carbon dioxide storage tank.

[0015] Specifically, the heat storage and heating system includes a low-temperature water tank. The low-temperature side of the low-temperature water tank is divided into two paths after passing through a circulating booster pump, a No. 1 heat exchanger and a heat storage tank in sequence. One path returns to the low-temperature water tank through a heat load user, and the other returns to the low-temperature water tank through a No. 2 heat exchanger.

[0016] Specifically, the cold storage and cooling system includes cold load users, and the input end of the cold load users is divided into two paths, one path is connected to the first cooling working fluid pump through the first cooling heat exchanger, and the other path is connected to the second cooling working fluid pump through the second cooling heat exchanger.

[0017] Another technical solution of the present invention is a working method of a cold, heat and electricity energy storage system based on a liquid carbon dioxide cycle, comprising the following:

[0018] Wind / solar power generation system consumption process:

[0019] When the power generation of the wind / solar power generation system is greater than or equal to the load of the power equipment, the wind / solar power generation system directly supplies the load demand of the power equipment, and the surplus power drives the operation of the energy storage system. At the same time, the energy storage system generates part of the power to supply the load of the power equipment; when the power generation of the wind / solar power generation system is less than the load of the power equipment, the wind / solar power generation system directly supplies the load demand of the power equipment, and at the same time, the energy release system operates, using the energy release system to generate power to supply the load of the power equipment;

[0020] Energy storage system energy storage process:

[0021] The 1MPa, -40.1℃ liquid carbon dioxide in the No. 1 carbon dioxide storage tank is cooled and decompressed, enters the regenerative heat exchanger to absorb heat and heat up, and then increases the pressure and temperature to obtain high-temperature carbon dioxide gas. The high-temperature carbon dioxide gas enters the No. 1 heat exchanger to transfer heat energy to the circulating water of the heating cycle. After that, the normal temperature and high-pressure carbon dioxide expands to a gas-liquid two-phase state. The gas phase carbon dioxide exchanges heat with the cooling working fluid in the No. 1 cooling heat exchanger to increase the temperature and then merges with the working fluid in the other direction to continue the compression energy storage process; the liquid phase carbon dioxide enters the No. 2 carbon dioxide storage tank for storage; the surplus electrical energy is converted into thermal energy for storage, and the rest is stored in the No. 2 carbon dioxide storage tank as low-temperature liquid carbon dioxide;

[0022] Energy release process of energy release system:

[0023] The liquid carbon dioxide in the No. 2 carbon dioxide storage tank is pressurized by a booster pump, and then exchanges heat with the cooling medium in the No. 2 cooling heat exchanger to increase the temperature. It then enters the No. 2 heat exchanger to exchange heat with the high-temperature hot water of the heat storage and heating system to increase the temperature. After the high-temperature and high-pressure supercritical carbon dioxide is used to generate electricity through a turbine, the carbon dioxide enters the regenerative heat exchanger to transfer its own heat to the cooling medium in the energy storage process to achieve carbon dioxide liquefaction, and then enters the No. 1 carbon dioxide storage tank for storage, realizing the conversion and release of stored energy into electrical energy through work.

[0024] Heat storage and heating system Heat storage mode: low-temperature water is pressurized and enters the No. 1 heat exchanger, absorbing the heat of high-temperature carbon dioxide in the energy storage process to become high-temperature water and store it;

[0025] Heating mode of heat storage and heating system: when supplying heat to the user end, high-temperature water is delivered to the heat load user side; when supplying heat to the energy release system, high-temperature water enters the No. 2 heat exchanger to heat the carbon dioxide in the energy release process, and then cools down to room temperature to complete the cycle of heat storage and heating process;

[0026] The cold storage and cooling process of the cold storage and cooling system:

[0027] The cold storage and cooling process includes two paths. One path runs simultaneously with the energy storage process. The cooling working fluid is pressurized and then exchanges heat with the No. 1 cooling heat exchanger for cooling, and then is stored. The other path runs simultaneously with the energy release process. The cooling working fluid is pressurized and then exchanges heat with the No. 2 cooling heat exchanger for cooling, and then is stored. When the user side requires cold load, the stored working fluid is used to achieve cooling.

[0028] Compared with the prior art, the present invention has at least the following beneficial effects:

[0029] The present invention discloses a combined cold, heat and electricity energy storage system based on liquid carbon dioxide circulation. The combined cold, heat and electricity energy storage technology of liquid carbon dioxide circulation is used to realize small-volume high-density storage of surplus electricity of wind / photovoltaic power generation systems in regional microgrids. When the power supply of wind / photovoltaic power generation systems in microgrids is insufficient, the stored energy is converted into electric energy to supply electricity to users. Since the whole system adopts liquid phase storage and the power cycle is based on carbon dioxide working fluid, the components have a compact structure and a small size, and are more suitable for arrangement in specific areas. In addition, the heat storage and heating system and the cold storage and cooling system are reasonably designed in combination with the cold and heat relationship in the system to realize combined cold, heat and electricity and optimize the cascade utilization of system energy. The system has important scientific significance and engineering application value for the development of the combined cold, heat and electricity system technology of regional microgrids.

[0030] Furthermore, a gas-liquid separator is provided to separate the gas phase and liquid phase carbon dioxide at the outlet of the cryogenic expander. The storage of liquid phase carbon dioxide in the No. 2 carbon dioxide storage tank helps save the storage tank volume and improve the system energy storage density; the gas phase carbon dioxide enters the electric three-way regulating valve after passing through the No. 1 cooling heat exchanger to increase the system circulating medium flow rate and improve the system energy storage density.

[0031] Furthermore, the energy storage process is a way to achieve the conversion of electrical energy into thermal energy of the carbon dioxide working fluid. The carbon dioxide compressor is the main component. The electric motor uses the electric drive of the wind / solar power generation system to coaxially drive the carbon dioxide compressor to start the working process. The function of the low-temperature expander is to reduce the pressure and temperature of carbon dioxide. The coaxially connected No. 1 generator will generate a small amount of electricity, which can be connected to the system to consume the power of the pump in the system.

[0032] Furthermore, a No. 1 valve is provided before the carbon dioxide enters the No. 2 carbon dioxide storage tank from the gas-liquid separator, and can be used as a switch valve for opening and closing the energy storage process of the system.

[0033] Furthermore, in the system described in the present invention, the wind / solar power generation system supplies electricity to electrical equipment on the one hand, and on the other hand, the remaining electricity drives the motor in the energy storage system to drive the carbon dioxide compressor to start the energy storage process; a part of the small amount of electricity generated by the No. 1 generator in the energy storage system can be supplied to the power consumption of the pump in the system, and the other part can also be used for consumption by electrical equipment. The energy release system can realize the conversion of energy from thermal energy storage form to electrical energy, connect users through the No. 2 generator, and provide electrical energy to electrical equipment.

[0034] Furthermore, increasing the inlet temperature and pressure of the turbine can increase the output power of the turbine. In order to increase the output power of the energy release system in the system described in the present invention, the low-pressure and low-temperature carbon dioxide liquid at the outlet of the No. 2 carbon dioxide storage tank is first pressurized by a booster pump, and then gradually absorbs heat through the No. 2 cooling heat exchanger and the No. 2 heat exchanger to become high-temperature and high-pressure carbon dioxide gas, which enters the turbine to output more power. The normal temperature and low-pressure carbon dioxide at the turbine outlet exchanges heat with the low-temperature cold storage material in the regenerative heat exchanger and is cooled to liquid carbon dioxide, which enters the No. 1 carbon dioxide storage tank for liquid storage, thereby increasing the energy storage density and completing the working fluid cycle of the energy storage process and the energy release process.

[0035] Furthermore, a No. 2 valve is provided between the No. 2 carbon dioxide storage tank and the booster pump, which can be used as a switch valve for opening and closing the energy release process of the system.

[0036] Furthermore, water is used as the working fluid of the heat storage system to store the heat energy converted by the system. The evaporation temperature of water is low under normal pressure. Therefore, the higher temperature storage required by the system can be achieved by pressurizing with a circulating booster pump. After heat exchange and heating in the No. 1 heat exchanger, the high-temperature water enters the heat storage tank for storage. Since the energy storage process and the energy release process of the system are separated in time and space, and the energy storage time is set to be greater than the energy release time, the hot water stored in the heat storage tank can supply heat to heat the temperature of the carbon dioxide at the turbine inlet during the energy release process, and can also supply part of the heat for the needs of heat load users. Then, the low-temperature water after heat exchange in the No. 2 heat exchanger enters the low-temperature water tank again for the next heat storage cycle.

[0037] Furthermore, there is available cold load in both the energy storage and release processes of the system. The temperature of carbon dioxide at the gas phase outlet of the gas-liquid separator is relatively low, and the inlet temperature of the carbon dioxide compressor is set at room temperature. Therefore, one path heats the carbon dioxide to room temperature through the No. 1 cooling heat exchanger, and at the same time, the cooling medium is cooled to a low temperature, thereby realizing the storage of the cold load; the other path utilizes low-temperature liquid carbon dioxide, and gasifies the carbon dioxide through heat exchange through the No. 2 cooling heat exchanger, and at the same time, the cooling medium is cooled to a low temperature, thereby realizing the storage of the cold load and supplying the cold load users.

[0038] The present invention discloses a working method of a cold, heat and electricity energy storage system based on the circulation of liquid carbon dioxide. The wind / solar power generation system belongs to renewable energy power generation, which has inherent properties such as volatility and discontinuity. The setting of the energy storage system can absorb electric energy through the carbon dioxide compression process in the form of energy conversion, realize the conversion of electric energy into mechanical energy and then store it in the form of thermal energy. When the user needs a stable power output, the energy release system is used to realize the conversion of thermal energy into mechanical energy and then into electric energy. At the same time, the user's load demand is diversified, and there may be a situation where both cold and hot loads are required. The thermal energy of carbon dioxide compression in the system and the cold load released by carbon dioxide liquefaction storage can meet certain cold and hot load demands of users.

[0039] In summary, the present invention can effectively store the surplus electricity of the wind / solar power generation system, utilize the compression heat load generated in the carbon dioxide compression process to achieve heat storage, utilize the liquefaction of carbon dioxide to achieve high-density storage and cold storage, and provide users with multiple forms of energy such as cold, heat and electricity.

[0040] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the system of the present invention.

[0042] Among them: wind / solar power generation equipment 1, No. 1 carbon dioxide storage tank 2, throttle valve 3, regenerative heat exchanger 4, electric three-way regulating valve 5, motor 6, carbon dioxide compressor 7, No. 1 heat exchanger 8, low-temperature expander 9, No. 1 generator 10, gas-liquid separator 11, No. 1 cooling heat exchanger 12, No. 1 valve 13, No. 2 carbon dioxide storage tank 14, No. 2 valve 15, booster pump 16, No. 2 cooling heat exchanger 17, No. 2 heat exchanger 18, turbine 19, No. 2 generator 20, electrical equipment 21, low-temperature water tank 22, No. 3 valve 23, circulating booster pump 24, No. 4 valve 25, heat storage tank 26, No. 5 valve 27, heat load user 28, No. 6 valve 29, No. 7 valve 30, No. 8 valve 31, No. 1 cooling working fluid pump 32, No. 9 valve 33, No. 10 valve 34, No. 2 cooling working fluid pump 35, cold load user 36. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are partial embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "one side", "one end", "one side" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, which are 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0045] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0047] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0048] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0049] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0050] The present invention discloses a combined cold, heat and electricity energy storage system based on liquid carbon dioxide circulation. The combined cold, heat and electricity energy storage technology of liquid carbon dioxide circulation is used to realize small-volume high-density storage of surplus electricity of wind / photovoltaic power generation systems in regional microgrids. When the power supply of wind / photovoltaic power generation systems in microgrids is insufficient, the stored energy is converted into electric energy to supply electricity to users. Since the whole system adopts liquid phase storage and the power cycle is based on carbon dioxide working fluid, the components have a compact structure and a small size, and are more suitable for arrangement in specific areas. In addition, the heat storage and heating system and the cold storage and cooling system are reasonably designed in combination with the cold and heat relationship in the system to realize combined cold, heat and electricity and optimize the cascade utilization of system energy. The system has important scientific significance and engineering application value for the development of the combined cold, heat and electricity system technology of regional microgrids.

[0051] See also Figure 1 The present invention discloses a cold, heat and electricity energy storage and supply system based on liquid carbon dioxide circulation, including a wind / solar power generation system, an energy storage system, an energy release system, a heat storage and heating system, and a cold storage and cooling system; carbon dioxide is used as the energy storage working fluid, based on the liquid phase storage of carbon dioxide, to store the excess new energy electricity of the power grid, and at the same time, by optimizing the utilization of cold / heat loads in the process of energy storage and release, it can meet the needs of user-side cooling and heating while meeting the needs of electricity storage, and can provide a meaningful idea for the construction and development of regional microgrids.

[0052] The wind / solar power generation system is connected to the energy storage system through the driving motor, the energy storage system is connected to the output side of the No. 1 carbon dioxide storage tank 2 through the regenerative heat exchanger 4, and the energy release system is connected to the energy storage system through the No. 2 carbon dioxide storage tank 14; the energy storage system is connected to the heat storage and heating system through the No. 1 heat exchanger 8, and the energy release system is connected to the heat storage and heating system through the No. 2 heat exchanger 18; the energy storage system is connected to the cold storage and cooling system through the No. 1 cooling heat exchanger 12, and the energy release system is connected to the cold storage and cooling system through the No. 1 cooling heat exchanger 17.

[0053] The energy storage system includes: a carbon dioxide compressor 7, a first heat exchanger 8, a low-temperature expander 9 and a gas-liquid separator 11.

[0054] The outlet of the No. 1 carbon dioxide storage tank 2 is connected to the inlet of the carbon dioxide compressor 7 via the throttle valve 3, the regenerative heat exchanger 4 and the electric three-way regulating valve 5, and the outlet of the carbon dioxide compressor 7 is connected to the gas-liquid separator 11 via the No. 1 heat exchanger 8 and the low-temperature expander 9.

[0055] The carbon dioxide in the No. 1 carbon dioxide storage tank 2 is stored at a pressure (1MPa) and a low temperature (-40.1°C), and is reduced in pressure to 0.6MPa by the throttle valve 3 and enters the regenerative heat exchanger 4 to be heated to room temperature, and then enters the carbon dioxide compressor 7 to be pressurized and heated, and enters the No. 1 heat exchanger 8 in a high temperature and high pressure state, transferring heat energy to the low-temperature water pressurized by the circulating booster pump 24, and then enters the low-temperature expander 9 in a normal temperature and high pressure state to expand, reduce pressure and liquefy, and the pressure drops to 1MPa again. The outlet of the expander is in a two-phase state and flows into the gas-liquid separator 11.

[0056] The wind / solar power generation system comprises: a wind / solar power generation device 1 and an electrical device 21 .

[0057] The distributed power source in the regional microgrid is composed of a wind / solar power generation device 1, which is respectively connected to an electric motor 6 and an electrical equipment 21, and the electric motor 6 is used to drive a carbon dioxide compressor 7; when electricity is abundant, the electric energy fully supplies the demand of the electrical equipment, and the excess electric energy drives the electric motor 6 to drive the carbon dioxide compressor 7 of the energy storage system; the electrical equipment 21 is connected to the low-temperature expander 9 via the No. 1 generator 10, and is connected to the turbine 19 via the No. 2 generator 20.

[0058] The energy release system includes: a No. 2 heat exchanger 18 and a turbine 19.

[0059] The gas-liquid separator 11 includes a gas phase outlet and a liquid phase outlet. The gas phase outlet of the gas-liquid separator 11 is connected to the electric three-way regulating valve 5 via the No. 1 cooling heat exchanger 12. The carbon dioxide at the gas phase outlet is heated by the No. 1 cooling heat exchanger 12 and then enters the electric three-way regulating valve 5 together with the carbon dioxide from the regenerative heat exchanger 4 to enter the carbon dioxide compressor 7 for compression and power consumption; the liquid phase outlet of the gas-liquid separator 11 is connected to the inlet of the No. 1 carbon dioxide storage tank 2 via the No. 1 valve 13, the No. 2 carbon dioxide storage tank 14, the No. 2 valve 15, the booster pump 16, the No. 2 cooling heat exchanger 17, the No. 2 heat exchanger 18, the turbine 19 and the regenerative heat exchanger, and the turbine 19 is connected to the No. 2 generator 20.

[0060] The liquid carbon dioxide at the liquid phase outlet enters the No. 2 carbon dioxide storage tank 14 through the No. 1 valve 13; the liquid carbon dioxide at 1MPa and -40.1℃ in the No. 2 carbon dioxide storage tank 14 flows out through the No. 2 valve 15, enters the booster pump 16 to be raised to high pressure, and then enters the No. 2 cooling heat exchanger 17, exchanges heat with the cooling medium to increase the temperature to become gaseous, and the gaseous carbon dioxide enters the No. 2 heat exchanger 18 to exchange heat and increase the temperature, and the high-temperature and high-pressure carbon dioxide gas then enters the turbine 19 to do work, driving the No. 2 generator 20 to output electricity, and the normal temperature and low-pressure carbon dioxide at the outlet of the turbine 19 enters the regenerative heat exchanger 4 to exchange heat with the cold load of the cold storage material to be cooled to become liquid, and enters the No. 1 carbon dioxide storage tank 2 for storage.

[0061] Heat storage and heating system: low temperature water tank 22, heat storage tank 26 and heat load user 28.

[0062] The low temperature of the low temperature water tank 22 is divided into two paths after passing through the No. 3 valve 23, the circulating booster pump 24, the No. 1 heat exchanger 8, the No. 4 valve 25 and the heat storage tank 26 in sequence. One path is connected to the heat load user 28 through the No. 5 valve 27 and returns to the low temperature water tank 22, and the other path is returned to the low temperature water tank 22 through the No. 7 valve 30, the No. 2 heat exchanger 18 and the No. 8 valve 31.

[0063] The low-temperature water in the low-temperature water tank 22 flows into the circulation booster pump 24 through the No. 3 valve 23 to be pressurized, and then enters the No. 1 heat exchanger 8 to absorb the heat of the high-temperature and high-pressure carbon dioxide gas at the outlet of the carbon dioxide compressor 7 to increase the temperature, and then enters the heat storage tank 26 for storage after passing through the No. 4 valve 25.

[0064] The circulating water at the outlet of the heat storage tank 26 is divided into two paths. One path is directly supplied to the heat load user 28 through the No. 5 valve 27, and then returns to the low-temperature water tank 22 through the No. 6 valve 29; the other path enters the No. 2 heat exchanger 18 through the No. 7 valve 30 to exchange heat with the normal temperature and high-pressure carbon dioxide in the energy release system, and then returns to the low-temperature water tank 22 through the No. 8 valve 31.

[0065] The cold storage and cooling supply system includes: cold load users 36.

[0066] The cold source in the cold load user 36 is provided by two cooling working fluids, including a No. 1 cooling working fluid pump 32 and a No. 2 cooling working fluid pump 35. The No. 1 cooling working fluid pump 32 is connected to the cold load user 36 via the No. 1 cooling heat exchanger 12 and the No. 9 valve 33, and the No. 2 cooling working fluid pump 35 is connected to the cold load user 36 via the No. 2 cooling heat exchanger 17 and the No. 10 valve 34. The cold load user 36 has a certain cold storage function.

[0067] The cooling medium is pressurized by the cooling medium pump 32 and then enters the cooling heat exchanger 12 to cool down the low-temperature and low-pressure carbon dioxide at the gas phase outlet of the energy storage system gas-liquid separator 11, and then enters the cooling load user 36 through the valve 33.

[0068] The other cooling medium is pressurized by the No. 2 cooling medium pump 35 and then enters the No. 2 cooling heat exchanger 17 to exchange heat with the low-temperature liquid carbon dioxide at the outlet of the energy release system booster pump 16 for cooling, and then enters the cooling load user 36 through the No. 10 valve 34 to realize cooling. The cooling load user 36 has a certain cold storage function.

[0069] It should be noted that the outlet of the carbon dioxide compressor 7 in the energy storage system and the inlet of the turbine 19 in the energy release system are both in a supercritical state, with a pressure greater than 7.5 MPa and a temperature greater than 35°C. The storage states of the No. 1 carbon dioxide storage tank 2 and the No. 2 carbon dioxide storage tank 14 are both in a low-pressure state, and the entire system is in a transcritical cycle state.

[0070] A working method of a cold, heat and electricity energy storage system based on liquid carbon dioxide circulation is as follows:

[0071] Wind / solar power generation system consumption process:

[0072] When the power generation of the wind / solar power generation system is greater than or equal to the load of the power equipment, the power of the wind / solar power generation equipment 1 is directly supplied to the load demand of the power equipment 21, and the surplus power drives the operation of the energy storage system. At the same time, the No. 1 generator 10 will generate part of the power to supply the load of the power equipment; when the power generation of the wind / solar power generation system is less than the load of the power equipment, the power of the wind / solar power generation equipment 1 is fully supplied to the demand of the power equipment 21, and at the same time, the energy release system is operated, using the turbine 19 to drive the No. 2 generator 20 to generate electricity to supply the power equipment 21.

[0073] Energy storage process:

[0074] In this process, the throttle valve 3 and the No. 1 valve 13 are opened, and the No. 2 valve 15 is closed. The liquid carbon dioxide of 1MPa and -40.1℃ in the No. 1 carbon dioxide storage tank 2 is cooled and decompressed by the throttle valve 3, enters the regenerative heat exchanger 4 to absorb heat and heat up, and then enters the carbon dioxide compressor 7 driven by the motor 6 through the electric three-way regulating valve 5 to increase the pressure and temperature. The high-temperature carbon dioxide gas at the outlet of the compressor enters the No. 1 heat exchanger 8, and transfers the heat energy to the circulating water pressurized by the circulating booster pump 24. Then, the carbon dioxide at room temperature and high pressure enters the low-temperature expander 9 to expand to a gas-liquid two-phase state, and then enters the gas-liquid separator 11, wherein the carbon dioxide at the gas phase outlet exchanges heat with the refrigerant through the No. 1 cooling heat exchanger 12 to increase the temperature, and then enters the electric three-way regulating valve 5 to merge with the refrigerant in the other direction to continue the compression and energy storage process; the carbon dioxide at the liquid phase outlet enters the No. 2 carbon dioxide storage tank 14 for storage; this process realizes the conversion of the surplus electric energy of the wind / photovoltaic power generation equipment 1 into thermal energy storage, and the rest is stored in the No. 2 carbon dioxide storage tank 14 as low-temperature liquid carbon dioxide.

[0075] Energy release process:

[0076] In this process, valve No. 13 is closed, valve No. 2 is opened, and booster pump 16 is running. Specifically, liquid carbon dioxide in No. 2 carbon dioxide storage tank 14 flows into booster pump 16 through valve No. 2 15 for pressurization, exchanges heat with cooling medium in No. 2 cooling heat exchanger 17 to increase its temperature, and then enters No. 2 heat exchanger 18 to exchange heat with high-temperature water from heat storage tank 26 to increase its temperature. Then, high-temperature and high-pressure supercritical carbon dioxide (pressure is greater than or equal to 7.5 MPa, temperature is greater than or equal to 35°C) enters turbine 19 to perform work and generate electricity. The carbon dioxide at the outlet of turbine 19 enters regenerative heat exchanger 4 to transfer its own heat to the cooling medium cooled in the energy storage process to realize carbon dioxide liquefaction, and enters No. 1 carbon dioxide storage tank 2 for storage. This process realizes the conversion and release of stored energy into electrical energy through the work of turbine 19.

[0077] Heat storage and heating process:

[0078] This process includes two modes: heat storage mode and heating mode. In the heat storage mode, valve No. 3 23 and valve No. 4 25 are opened, valve No. 8 31, valve No. 5 27 and valve No. 7 30 are closed. At this time, the low-temperature water in the low-temperature water tank 22 is pressurized by the circulating booster pump 24 and enters the heat exchanger No. 1 8. It absorbs the heat of the high-temperature carbon dioxide at the outlet of the carbon dioxide compressor 7 during the energy storage process and becomes high-temperature water, which is stored in the heat storage tank 26. In the heating mode, valve No. 3 23 and valve No. 4 25 are closed, valve No. 8 31 is opened, valve No. 5 27 is closed, and valve No. 6 is closed. / When valve No. 7 30 is opened and heat is supplied to the user, valve No. 5 27 is opened, and high-temperature water flows out of the heat storage tank 26 and is delivered to the heat load user 28 through valve No. 5 27; when heat is supplied to the energy release system, high-temperature water in the heat storage tank 26 flows out through valve No. 7 30 and enters the No. 2 heat exchanger 18 to heat the carbon dioxide in the energy release process, and then the high-temperature water is cooled to room temperature and enters the low-temperature water tank 22 to complete the cycle of heat storage and heat supply process; the entire heat storage and heat supply process can be associated with the energy storage process and the energy release process to realize the storage and utilization of heat load.

[0079] Cold storage and cooling process:

[0080] The cold storage and cooling process includes two paths. One path runs simultaneously with the energy storage process. At this time, valve No. 9 33 is opened and valve No. 10 34 is closed. The cooling medium is pressurized by cooling medium pump No. 1 32 and then exchanges heat with cooling heat exchanger No. 1 12 for cooling. Then, it passes through valve No. 9 33 to enter cooling load user 36 for cooling. The other path runs simultaneously with the energy release process. At this time, valve No. 9 33 is closed and valve No. 10 34 is opened. The cooling medium is pressurized by cooling medium pump No. 2 35 and then exchanges heat with cooling heat exchanger No. 2 17 for cooling. Then, it passes through valve No. 10 34 to enter cooling load user 36 for cooling. The entire cold storage and cooling system is also associated with the energy storage process and the energy release process to realize the storage and utilization of cooling load.

[0081] According to the simulation calculation of Matlab tool, the energy storage density (output power of energy release process / volume of liquid storage tank) and round-trip efficiency (output power of energy release process / power consumed in energy storage process) of the system are used as the evaluation indexes of the system. The energy storage density of the system can reach 20.6kWh / m3 and the round-trip efficiency can reach 50.8%, which can indicate that the system is in a high-efficiency operation state.

[0082] In summary, the present invention is a cold, heat and electricity energy storage and supply system based on liquid carbon dioxide circulation, which can reasonably absorb the new energy electricity of the wind / photovoltaic power generation system in the regional microgrid. The storage method of liquid carbon dioxide is conducive to engineering construction based on the actual scale of the region, and can reasonably store the cold and heat loads in the system while storing electricity, and can simultaneously realize heating and cooling for regional users, and has good engineering application value.

[0083] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A cooling, heating and electricity energy storage system based on liquid carbon dioxide circulation, characterized in that: The invention comprises a first carbon dioxide liquid storage tank (3), wherein the outlet side of the first carbon dioxide liquid storage tank (3) is connected to the inlet side of the first carbon dioxide liquid storage tank (3) via a regenerative heat exchanger (4), an energy storage system, a second carbon dioxide liquid storage tank (14), an energy release system and a regenerative heat exchanger (4) in sequence to form a loop, and the energy storage system is connected to a wind / solar power generation system via a driving motor to realize energy storage and energy release; The energy storage system is connected to the heat storage and heat supply system via the first heat exchanger (8), and the heat storage and heat supply system is connected to the energy release system via the second heat exchanger (18), so as to realize heat storage and heat supply; The energy storage system is connected to the cold storage and cold supply system via a No. 1 cold supply heat exchanger (12), and the energy release system is connected to the cold storage and cold supply system via a No. 2 cold supply heat exchanger (17), so as to realize cold storage and cold supply.

2. The cold, heat and electricity energy storage system based on liquid carbon dioxide circulation according to claim 1 is characterized in that: The energy storage system comprises a carbon dioxide compressor (7), a regenerative heat exchanger (4) connected to the inlet of the carbon dioxide compressor (7) via an electric three-way regulating valve (5), the outlet of the carbon dioxide compressor (7) connected to a gas-liquid separator (11) via a No. 1 heat exchanger (8) and a low-temperature expander (9), the outlet of the gas-liquid separator (11) is divided into two paths, one path is connected to the electric three-way regulating valve (5) via a No. 1 cooling heat exchanger (12), and the other path is connected to the energy release system via a No. 2 carbon dioxide storage tank (14).

3. The cold, heat and electricity energy storage system based on liquid carbon dioxide circulation according to claim 2 is characterized in that: The low-temperature expander (9) is connected to the wind / solar power generation system via the No. 1 generator (10), and the carbon dioxide compressor (7) is connected to the wind / solar power generation system via the electric motor (2).

4. The cold, heat and electricity energy storage system based on liquid carbon dioxide circulation according to claim 2 is characterized in that: A first valve (13) is provided between the gas-liquid separator (11) and the second carbon dioxide storage tank (14).

5. The cold, heat and electricity energy storage system based on liquid carbon dioxide circulation according to claim 1 is characterized in that: The wind / solar power generation system comprises a wind / solar power generation device (1), wherein the wind / solar power generation device (1) is connected to a carbon dioxide compressor (7) of an energy storage system via an electric motor (2), and the wind / solar power generation device (1) is connected to a No. 1 generator (10) of an energy storage system and a No. 2 generator (20) of an energy release system via an electrical device (21).

6. The cold, heat and electricity energy storage system based on liquid carbon dioxide circulation according to claim 1 is characterized in that: The energy release system includes a turbine (19), the outlet of the turbine (19) is connected to the regenerative heat exchanger (4), and the inlet of the turbine (19) is connected to the outlet side of the second carbon dioxide storage tank (14) via the second heat exchanger (18), the second cooling heat exchanger (17) and the booster pump (16) in sequence.

7. The cold, heat and electricity energy storage system based on liquid carbon dioxide circulation according to claim 6 is characterized in that: A second valve (15) is provided between the booster pump (16) and the second carbon dioxide storage tank (14).

8. The cold, heat and electricity energy storage system based on liquid carbon dioxide circulation according to claim 1 is characterized in that: The heat storage and heat supply system comprises a low-temperature water tank (22). The low-temperature water side of the low-temperature water tank (22) is sequentially passed through a circulation booster pump (24), a No. 1 heat exchanger (8) and a heat storage tank (26) and then divided into two paths, one path returning to the low-temperature water tank (22) through a heat load user (28), and the other path returning to the low-temperature water tank (22) through a No. 2 heat exchanger (18).

9. The cold, heat and electricity energy storage system based on liquid carbon dioxide circulation according to claim 1 is characterized in that: The cold storage and supply system includes a cold load user (36). The input end of the cold load user (36) is divided into two paths, one path is connected to a first cold supply working fluid pump (32) via a first cold supply heat exchanger (12), and the other path is connected to a second cold supply working fluid pump (35) via a second cold supply heat exchanger (17).

10. The cold, heat and electricity energy storage system based on liquid carbon dioxide circulation according to claim 1 is characterized in that: These include: Wind / solar power generation system consumption process: When the power generation of the wind / solar power generation system is greater than or equal to the load of the power equipment, the wind / solar power generation system directly supplies the load demand of the power equipment, and the surplus power drives the operation of the energy storage system. At the same time, the energy storage system generates part of the power to supply the load of the power equipment; when the power generation of the wind / solar power generation system is less than the load of the power equipment, the wind / solar power generation system directly supplies the load demand of the power equipment, and at the same time, the energy release system operates, using the energy release system to generate power to supply the load of the power equipment; Energy storage system energy storage process: The liquid carbon dioxide at 1MPa and -40.1℃ in the No.1 carbon dioxide storage tank is cooled and decompressed, enters the regenerative heat exchanger to absorb heat and heat up, and then increases the pressure and temperature to obtain high-temperature carbon dioxide gas. The high-temperature carbon dioxide gas enters the No.1 heat exchanger to transfer heat energy to the circulating water of the heating cycle. After that, the carbon dioxide at room temperature and high pressure expands to a gas-liquid two-phase state. The gas phase carbon dioxide exchanges heat with the cooling working fluid in the No.1 cooling heat exchanger to increase the temperature, and then merges with the working fluid in the other direction to continue the compression and energy storage process. The liquid carbon dioxide enters the No. 2 carbon dioxide storage tank for storage; the surplus electric energy is converted into thermal energy for storage, and the rest is stored in the No. 2 carbon dioxide storage tank as low-temperature liquid carbon dioxide; Energy release process of energy release system: The liquid carbon dioxide in the No. 2 carbon dioxide storage tank is pressurized by a booster pump, and then exchanges heat with the cooling medium in the No. 2 cooling heat exchanger to increase the temperature. It then enters the No. 2 heat exchanger to exchange heat with the high-temperature hot water of the heat storage and heating system to increase the temperature. After the high-temperature and high-pressure supercritical carbon dioxide is used to generate electricity through a turbine, the carbon dioxide enters the regenerative heat exchanger to transfer its own heat to the cooling medium in the energy storage process to achieve carbon dioxide liquefaction, and then enters the No. 1 carbon dioxide storage tank for storage, realizing the conversion and release of stored energy into electrical energy through work. Heat storage and heating system Heat storage mode: low-temperature water is pressurized and enters the No. 1 heat exchanger, absorbing the heat of high-temperature carbon dioxide in the energy storage process to become high-temperature water and store it; Heating mode of heat storage and heating system: when supplying heat to the user end, high-temperature water is delivered to the heat load user side; when supplying heat to the energy release system, high-temperature water enters the No. 2 heat exchanger to heat the carbon dioxide in the energy release process, and then cools down to room temperature to complete the cycle of heat storage and heating process; The cold storage and cooling process of the cold storage and cooling system: The cold storage and cooling process includes two paths. One path runs simultaneously with the energy storage process. The cooling working fluid is pressurized and then exchanges heat with the No. 1 cooling heat exchanger for cooling, and then is stored. The other path runs simultaneously with the energy release process. The cooling working fluid is pressurized and then exchanges heat with the No. 2 cooling heat exchanger for cooling, and then is stored. When the user side requires cold load, the stored working fluid is used to achieve cooling.

Images