A large-scale combined cooling and power energy storage system with composite working fluid and adjustable frequency

Abstract

The present invention discloses a large-scale combined cooling and power energy storage system with frequency adjustment of composite working fluid, including a working medium high-pressure gas storage tank, etc.; the working medium flowing out of the high-pressure gas storage tank and the air flowing into the air pipeline are mixed and then passed into the compressor, and then passed through the first heat exchanger, the condenser and the gas-liquid separator to separate the air and the working medium liquid; the gas outlet of the gas-liquid separator is connected to the low-temperature air storage tank, and is connected to the atmosphere through the first heater and the air turbine to form an air flow path; the liquid outlet of the gas-liquid separator is connected to the working medium liquid storage tank, and returns to the high-pressure gas storage tank through the second heater and the working medium turbine to form a working medium loop; the energy storage medium in the cold storage tank enters the heat storage tank through the first heat exchanger, and returns to the cold storage tank through the first and second heaters to form an energy storage medium loop. The present invention couples compressed air energy storage and liquid-gas compression energy storage, and has the advantages of adjustable power and frequency, strong system flexibility, etc., and can provide cooling capacity at the same time to realize comprehensive energy utilization.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage, and in particular relates to a large-scale combined cooling and power energy storage system with adjustable frequency using composite working fluids. Background Art

[0002] Energy has always been a prerequisite for human civilization and the material basis for the survival and development of human society. It has a particularly important strategic position in the national economy. The current production and lifestyle of human beings makes the energy load present the characteristics of high during the day and low at night, which puts higher requirements on the peak-shaving capacity of the power grid. At the same time, renewable clean energy such as wind energy, solar energy and hydropower has randomness and large volatility under the constraints of natural conditions, poor stability, and it is difficult to meet the needs of the power grid.

[0003] Energy storage technology can realize the time-sharing storage and release of energy, which can effectively reduce the peak-shaving pressure of the power grid and improve the utilization rate of renewable energy generation. The existing energy storage technologies mainly include pumped storage, electrochemical energy storage, electromagnetic energy storage and compressed gas energy storage. Pumped storage can convert energy into the potential energy of water for storage, which can realize large-scale energy storage, but its response speed is slow and has certain requirements for geographical resources. Electrochemical energy storage and electromagnetic energy storage have large specific energy and fast response, but the construction cost is high and the safety performance needs to be improved. The existing compressed gas energy storage technologies mainly include compressed air energy storage and compressed carbon dioxide energy storage. The compressed air energy storage system has a fast response speed, but due to the low energy density of air, the system is relatively large and the overall construction cost is high. Carbon dioxide has a high liquefaction temperature and high energy density, so the compressed carbon dioxide energy storage system has a low cost but a slow response.

[0004] Therefore, there is an urgent need to develop a large-scale energy storage system with a simple structure, suitable for a variety of usage scenarios, and adjustable frequency. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a large-scale combined cooling and power energy storage system with adjustable frequency of composite working fluid. The composite working fluid energy storage system proposed in the present invention couples compressed air energy storage and liquid-gas compression energy storage, and has the advantages of adjustable power and frequency, strong system flexibility, etc. At the same time, it can provide cooling capacity and realize the comprehensive utilization of energy.

[0006] The present invention is implemented by the following technical solutions:

[0007] A composite working medium frequency adjustable large-scale combined cooling and power energy storage system, comprising a working medium high-pressure gas storage tank, a control valve, a compressor, a first heat exchanger, a condenser, a gas-liquid separator, an air low-temperature gas storage tank, a working medium liquid storage tank, a first heater, a second heater, an air turbine, a working medium turbine, a cold storage tank and a heat storage tank;

[0008] The working medium flowing out of the working medium high-pressure gas storage tank and the air entering from the air pipeline are mixed and then passed into the compressor, and then pass through the first flow channel of the first heat exchanger and then pass through the condenser and the gas-liquid separator respectively to separate the low-temperature air and the working medium liquid;

[0009] The gas outlet of the gas-liquid separator is connected to the low-temperature air storage tank, and then communicated with the atmosphere through the first flow channel of the first heater and the air turbine, forming a first air flow path;

[0010] The liquid outlet of the gas-liquid separator is connected to the working medium storage tank, and then returns to the working medium high-pressure gas storage tank through the first flow channel of the second heater and the working medium turbine, forming a working medium circulation loop;

[0011] The energy storage medium in the cold storage tank enters the heat storage tank after passing through the second flow channel of the first heat exchanger, and the heat storage tank outlet is connected with the second flow channel inlet of the first heater and the second flow channel inlet of the second heater, and returns to the cold storage tank after passing through the first heater and the second heater respectively, forming an energy storage medium circulation loop.

[0012] A further improvement of the present invention is that control valves are arranged between the heat storage tank and the first heater, between the heat storage tank and the second heater, between the low-temperature air storage tank and the first heater, and between the liquid storage tank and the second heater. When the electricity demand is low, the four control valves are closed to transfer energy to the energy storage medium and store it in the heat storage tank. When the electricity demand is high, the four control valves are opened to convert the energy stored in the energy storage medium into electrical energy.

[0013] A further improvement of the present invention is that the outlet of the low-temperature air storage tank is connected to the second heat exchanger and is finally discharged into the atmosphere to form a second air flow path to meet the user's demand for cooling capacity.

[0014] A further improvement of the present invention is that the working medium turbine is a high-power turbine to meet the user's demand for high-power stable electric energy.

[0015] A further improvement of the present invention is that the air turbine is a low-power fast turbine to meet the user's demand for low-power flexible electricity.

[0016] A further improvement of the present invention is that regulating valves are provided between the low-temperature air storage tank and the first heater, and between the low-temperature air storage tank and the second heat exchanger to adjust the ratio of low-temperature air entering the first air flow path and the second air flow path.

[0017] A further improvement of the present invention is that a control valve is arranged at the outlet of the working medium high-pressure gas storage tank and the inlet of the air pipeline to adjust the ratio of the components in the mixed gas entering the compressor, so that the ratio of air to working medium in the mixed gas is within a reasonable range to meet the requirements. Where V airis the volume fraction of air in the mixed gas, is the volume fraction of the working medium in the mixed gas.

[0018] A further improvement of the present invention is that the working medium is carbon dioxide.

[0019] A further improvement of the present invention is that the energy storage medium is saturated water or heat transfer oil.

[0020] A further improvement of the present invention is that the heat storage tank and the cold storage tank are connected in parallel according to actual capacities.

[0021] The present invention has at least the following beneficial technical effects:

[0022] 1. The present invention is a large-scale combined cooling and power energy storage system with frequency regulation of composite working fluids, which realizes combined cooling and power through a second heat exchanger, a low-power air turbine and a high-power working medium turbine. When the electricity demand is low, the electric energy can be transferred to the energy storage medium and stored in the heat storage tank. When the electricity demand is high, the energy stored in the energy storage medium can be converted back into electric energy, which can not only reduce the peak-shaving pressure of the power grid, but also reduce the degree of restriction of renewable energy by natural conditions, and improve the utilization rate of renewable energy power generation.

[0023] 2. The composite working fluid adjustable frequency large-scale combined cooling and power energy storage system of the present invention couples compressed air energy storage and liquid-gas compression energy storage. Compared with the compressed air energy storage system, the overall construction cost is lower, and compared with the liquid-gas compression energy storage system, the system response is faster. The system has a small demand for geographical resources, high safety, low construction and maintenance costs, and can achieve flexible operation.

[0024] 3. The present invention can adjust the supply ratio of the working medium and air in the system by adjusting the opening of the flow control valve between the outlet of the working medium high-pressure gas storage tank and the inlet of the air pipeline, and can adjust the ratio of air entering the first air flow path and the second air flow path by adjusting the opening of the control valve between the outlet of the air low-temperature gas storage tank and the first heater and the second heat exchanger, thereby realizing the adjustment of the system output power and frequency as well as the output cooling power, and meeting the user's needs for high-power electricity, low-power flexible electricity, and cooling in different usage scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a structural schematic diagram of a large-scale combined cooling and power energy storage system with composite working fluid and adjustable frequency proposed by the present invention.

[0026] Description of reference numerals:

[0027] 1. Carbon dioxide high-pressure gas storage tank; 2. Compressor; 3. First heat exchanger; 4. Condenser; 5. Gas-liquid separator; 6. Air low-temperature gas storage tank; 7. Carbon dioxide liquid storage tank; 8. First heater; 9. Second heater; 10. Air turbine; 11. Carbon dioxide turbine; 12. Heat storage tank; 13. Cold storage tank; 14. Second heat exchanger; 101. First control valve; 102. Second control valve; 103. Third control valve; 104. Fourth control valve; 105. Fifth control valve; 106. Sixth control valve; 107. Seventh control valve. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical effect and technical solution of the embodiments of the present invention clearer, the present invention is described in detail below in conjunction with the embodiments and drawings. The protection scope of the present invention is not limited to the embodiments, and any changes made by those skilled in the art within the scope defined by the claims also fall within the protection scope of the present invention.

[0029] See also Figure 1 In an embodiment of the present invention, a composite working fluid adjustable frequency large-scale combined cooling and power energy storage system is provided, wherein the working medium is carbon dioxide and the energy storage medium is heat transfer oil, and the system includes: a carbon dioxide circulation loop component, an air flow path component, and a heat transfer oil circulation loop component.

[0030] The carbon dioxide circulation loop assembly specifically comprises:

[0031] The outlet of the carbon dioxide high-pressure gas storage tank 1 is connected to the inlet of the compressor 2, the outlet of the compressor 2 is connected to the inlet of the first flow channel of the first heat exchanger 3, the outlet of the first flow channel of the first heat exchanger 3 is connected to the inlet of the condenser 4, the outlet of the condenser 4 is connected to the inlet of the gas-liquid separator 5, the liquid outlet of the gas-liquid separator 5 is connected to the carbon dioxide liquid storage tank 7, the outlet of the carbon dioxide liquid storage tank 7 is connected to the inlet of the first flow channel of the second heater 9, the outlet of the first flow channel of the second heater 9 is connected to the inlet of the carbon dioxide turbine 11, and the outlet of the carbon dioxide turbine 11 is connected to the inlet of the carbon dioxide high-pressure gas storage tank.

[0032] The air flow path component specifically comprises:

[0033] After the atmospheric pressure air is mixed with the carbon dioxide working medium, it flows out from the gas outlet of the gas-liquid separator 5 after passing through the compressor 2, the heat exchanger 3, the condenser 4, and the gas-liquid separator 5. The gas outlet of the gas-liquid separator 5 is connected to the inlet of the low-temperature air storage tank 6. After that, the air flows into the first air flow path and the second air flow path respectively. Among them, the first air flow path is: the outlet of the low-temperature air storage tank 6 is connected to the inlet of the first flow channel of the first heater 8, and the high-temperature and high-pressure gas flowing out of the first flow channel outlet of the first heater 8 is passed into the low-power fast air turbine 10, and finally discharged into the atmosphere; the second air flow path is: the outlet of the low-temperature air storage tank 6 is connected to the inlet of the first flow channel of the second heat exchanger 14, and it flows out from the outlet of the first flow channel of the second heat exchanger 14 and is discharged into the atmosphere.

[0034] The thermal oil circulation loop assembly specifically comprises:

[0035] The outlet of the cold storage tank 13 is connected to the inlet of the second flow channel of the first heat exchanger 3, the outlet of the second flow channel of the first heat exchanger 3 is connected to the inlet of the heat storage tank 12, the outlet of the heat storage tank 12 is connected to the inlet of the second flow channel of the first heater 8 and the inlet of the second flow channel of the second heater 9, and the heat transfer oil flows out from the outlet of the second flow channel of the first heater 8 and the outlet of the second flow channel of the second heater 9 respectively and then returns to the cold storage tank.

[0036] A first control valve 101 is provided between the outlet of the carbon dioxide high-pressure gas storage tank 1 and the inlet of the compressor 2 .

[0037] A second control valve 102 is provided between the atmospheric pressure air inlet and the compressor 2 inlet.

[0038] A third control valve 103 is provided between the outlet of the low-temperature air storage tank 6 and the inlet of the first flow channel of the second heat exchanger 14 .

[0039] A fourth control valve 104 is provided between the outlet of the low-temperature air storage tank 6 and the inlet of the first flow channel of the first heater 8 .

[0040] A fourth control valve 106 is provided between the outlet of the carbon dioxide storage tank 7 and the inlet of the first flow channel of the second heater 9 .

[0041] A fifth control valve 105 is provided between the outlet of the heat storage tank 12 and the inlet of the second flow channel of the first heater 8 .

[0042] A seventh control valve 107 is provided between the outlet of the heat storage tank 12 and the inlet of the second flow channel of the second heater 9 .

[0043] Furthermore, the pressure in the carbon dioxide high-pressure gas storage tank 1 is 7-16 bar, and the air inlet pressure is 1 bar. By adjusting the opening of the first control valve 101 and the second control valve 102, the ratio of the mixed gas components entering the compressor 2 can be adjusted. The ratio of air to carbon dioxide in the mixed gas should be within a reasonable range to meet the requirements. Where V air is the volume fraction of air in the mixed gas, is the volume fraction of carbon dioxide in the mixed gas.

[0044] Furthermore, the air turbine 10 is a low-power fast turbine, and the carbon dioxide turbine 11 is a high-power turbine, so as to meet the user's demand for high-power stable electricity and low-power flexible electricity.

[0045] Furthermore, the cold end of the second heat exchanger 14 is the user, and the coldness provided by the low-temperature air is used to meet the user's coldness demand.

[0046] A cooling and power cogeneration energy storage system coupled with compressed air and compressed carbon dioxide according to an embodiment of the present invention includes an energy storage process and an energy release process, specifically including the following steps:

[0047] During the energy storage process, the first control valve 101 and the second control valve 102 are opened, and the third control valve 103, the fourth control valve 104, the fifth control valve 105, the sixth control valve 106, and the seventh control valve 107 are closed. The energy to be stored drives the compressor 2 to work, and the mixed gas is heated and pressurized, and then passes through the first heat exchanger 3 to exchange heat with the heat transfer oil, and the heat is transferred to the heat transfer oil. After that, the mixed gas enters the condenser for condensation, and the gaseous air and the liquid carbon dioxide are separated by the gas-liquid separator, and are stored in the low-temperature air storage tank 6 and the carbon dioxide storage tank 7 respectively. The heat transfer oil is stored in the heat storage tank 12 after heat exchange. After the heat transfer oil in the heat storage tank is stored, the first control valve 101 and the second control valve 102 are closed, and the energy storage process is completed.

[0048] During the energy release process, the first control valve 101 and the second control valve 102 are closed, and the third control valve 103, the fourth control valve 104, the fifth control valve 105, the sixth control valve 106, and the seventh control valve 107 are opened. The energy release process can be divided into three parts, wherein the first part is: the low-temperature air in the low-temperature air storage tank passes through the second heat exchanger 14 to provide coldness to the user; the second part is: the low-temperature air in the low-temperature air storage tank is heated by the heat transfer oil through the first heater 8, and then enters the low-power fast air turbine to expand and do work, and finally discharged into the atmosphere, and the air turbine drives the generator to generate electricity. The third part is: the liquid carbon dioxide in the carbon dioxide storage tank is heated by the heat transfer oil through the second heater 9, and converted into high-temperature and high-pressure gaseous carbon dioxide, and then enters the high-power carbon dioxide turbine to expand and do work, and the carbon dioxide turbine drives the generator to generate electricity. In the actual operation process, the utilization ratio of the three parts can be adjusted by adjusting the opening of the control valves 103 to 107 according to actual needs. When the heat transfer oil in the heat storage tank, the low-temperature air in the low-temperature air storage tank or the liquid carbon dioxide in the carbon dioxide storage tank is completely consumed, the control valves 103-107 are closed and the energy release process is completed.

[0049] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The above only illustrates the embodiments of the present invention, but cannot serve as the entire protection scope of the present invention. Ordinary technicians in the relevant field can still modify or replace the specific implementation methods of the present invention with equivalents. Any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the protection scope of the claims of the present invention to be approved.

Claims

1. A large-scale combined cooling and power energy storage system with composite working fluid and adjustable frequency. It is characterized in that It includes a working medium high-pressure gas storage tank, a control valve, a compressor, a first heat exchanger, a condenser, a gas-liquid separator, an air low-temperature gas storage tank, a working medium liquid storage tank, a first heater, a second heater, an air turbine, a working medium turbine, a cold storage tank and a heat storage tank; The working medium flowing out of the working medium high-pressure gas storage tank and the air entering from the air pipeline are mixed and then passed into the compressor, and then pass through the first flow channel of the first heat exchanger and then pass through the condenser and the gas-liquid separator respectively to separate the low-temperature air and the working medium liquid; The gas outlet of the gas-liquid separator is connected to the low-temperature air storage tank, and then communicated with the atmosphere through the first flow channel of the first heater and the air turbine, forming a first air flow path; The liquid outlet of the gas-liquid separator is connected to the working medium storage tank, and then returns to the working medium high-pressure gas storage tank through the first flow channel of the second heater and the working medium turbine, forming a working medium circulation loop; The energy storage medium in the cold storage tank enters the heat storage tank after passing through the second flow channel of the first heat exchanger, and the heat storage tank outlet is connected with the second flow channel inlet of the first heater and the second flow channel inlet of the second heater, and returns to the cold storage tank after passing through the first heater and the second heater respectively, forming an energy storage medium circulation loop.

2. A composite working fluid frequency-adjustable large-scale combined cooling and power energy storage system according to claim 1, It is characterized in that Control valves are arranged between the heat storage tank and the first heater, between the heat storage tank and the second heater, between the low-temperature air storage tank and the first heater, and between the liquid storage tank and the second heater. When the electricity demand is low, the four control valves are closed to transfer energy to the energy storage medium and store it in the heat storage tank. When the electricity demand is high, the four control valves are opened to convert the energy stored in the energy storage medium into electrical energy.

3. A composite working fluid frequency-adjustable large-scale combined cooling and power energy storage system according to claim 1, It is characterized in that The outlet of the low-temperature air storage tank is connected to the second heat exchanger and is finally discharged into the atmosphere, forming a second air flow path to meet the user's demand for cooling capacity.

4. A large-scale combined cooling and power energy storage system with adjustable frequency using composite working fluid according to claim 1, It is characterized in that The working medium turbine is a high-power turbine to meet the user's demand for high-power stable electricity.

5. A large-scale combined cooling and power energy storage system with adjustable frequency using composite working fluid according to claim 1, It is characterized in that The air turbine is a low-power fast turbine to meet the user's demand for low-power flexible electricity.

6. A composite working fluid frequency-adjustable large-scale combined cooling and power energy storage system according to claim 1, It is characterized in that Regulating valves are arranged between the low-temperature air storage tank and the first heater, and between the low-temperature air storage tank and the second heat exchanger to adjust the ratio of low-temperature air entering the first air flow path and the second air flow path.

7. A large-scale combined cooling and power energy storage system with adjustable frequency using composite working fluid according to claim 1, It is characterized in that The working medium high pressure gas tank outlet and the air pipeline inlet are both equipped with control valves to adjust the ratio of the components in the mixed gas entering the compressor. The ratio of air to working medium in the mixed gas is within a reasonable range to meet the requirements. Where V air is the volume fraction of air in the mixed gas, is the volume fraction of the working medium in the mixed gas.

8. A composite working fluid frequency-adjustable large-scale combined cooling and power energy storage system according to claim 1, It is characterized in that The working medium is carbon dioxide.

9. A composite working fluid frequency-adjustable large-scale combined cooling and power energy storage system according to claim 1, It is characterized in that The energy storage medium is saturated water or heat transfer oil.

10. A composite working fluid frequency-adjustable large-scale combined cooling and power energy storage system according to claim 1, It is characterized in that The heat storage tank and the cold storage tank are connected in parallel according to the actual capacity.

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