A heat recovery system, a compression energy storage system and a heat recovery method

Abstract

The present invention discloses a heat recovery system, a compression energy storage system and a heat recovery method, and relates to the technical field of compression energy storage. The system comprises: a first storage tank and a second storage tank, wherein the first storage tank is used to store a heat exchange medium at normal pressure, and the second storage tank is used to store a heat exchange medium exceeding a first preset pressure; the first preset pressure is a saturation pressure corresponding to a maximum heating temperature of the compression energy storage system during energy storage; the heat exchange medium flowing out of the first storage tank exchanges heat energy with an energy storage heat exchange side of the compression energy storage system after being pressurized and exceeding the first preset pressure, and flows into the second storage tank for storage; the heat exchange medium stored in the second storage tank is kept at a pressure exceeding the first preset pressure by a pressure maintaining mechanism; the heat exchange medium flowing out of the second storage tank exchanges heat energy with an energy release heat exchange side of the compression energy storage system, and flows into the first storage tank for storage.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed energy storage, and in particular to a heat energy recovery system, a compressed energy storage system and a heat energy recovery method. Background Art

[0002] Compressed energy storage is a gas-liquid or liquid-liquid energy storage technology. It has the advantages of high efficiency, no risk of combustion and explosion, and excellent environmental protection performance. It has a wide range of power, capacity, and regional adaptability. By controlling the operating time of the energy storage process and the energy release process, it can flexibly and conveniently adjust the storage capacity and energy release capacity. It is not restricted by geographical location and is a large-scale clean physical energy storage technology with great development prospects.

[0003] The basic principle of compression storage technology is to use excess or surplus electricity to drive the electric motor to compress gas at normal temperature and pressure into high-pressure gas or high-pressure liquid during the period of low electricity consumption, and store the heat energy generated during the compression process; during the peak period of electricity consumption, the heat energy stored during the period of low electricity consumption and the waste heat of the power plant are used to heat the high-pressure gas or high-pressure liquid to liquid state, and drive the expander to generate electricity.

[0004] Whether it is a gas-liquid or liquid-liquid compression energy storage system, if the compressed heat energy of the compressor outlet gas is to be stored as high-quality heat energy, heat transfer oil with a higher boiling point is required as the heat recovery medium. The heat recovery system requires a very large amount of heat transfer oil, and the heat transfer oil needs to be replaced after long-term use. Therefore, the investment cost of using heat transfer oil in the heat recovery system is extremely high, resulting in a high cost of carbon dioxide energy storage. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a heat recovery system, a compression energy storage system and a heat recovery method to solve the problem of high cost of using existing heat exchange media.

[0006] According to a first aspect, an embodiment of the present invention provides a heat recovery system, the system comprising:

[0007] a first storage tank and a second storage tank, wherein the first storage tank is used to store a heat exchange medium at normal pressure, and the second storage tank is used to store the heat exchange medium at a pressure exceeding a first preset pressure; the first preset pressure is a saturation pressure corresponding to the maximum heating temperature of the compressed energy storage system during energy storage;

[0008] The heat exchange medium flowing out of the first storage tank exchanges heat energy with the energy storage heat exchange side of the compressed energy storage system after being pressurized to exceed the first preset pressure, and flows into the second storage tank for storage; the heat exchange medium stored in the second storage tank is kept at a pressure exceeding the first preset pressure by a pressure maintaining mechanism;

[0009] The heat exchange medium flowing out of the second storage tank exchanges heat energy with the energy release heat exchange side of the compressed energy storage system and flows into the first storage tank for storage;

[0010] The heat exchange medium remains in liquid form when stored in the first and second storage tanks and when exchanging heat energy with the compressed energy storage system.

[0011] In the heat recovery system provided by the embodiment of the present invention, the heat exchange medium will be pressurized to exceed the first preset pressure before exchanging heat with the energy storage heat exchange side of the energy storage subsystem. Therefore, the heat exchange medium is kept in liquid form when storing in the first storage tank and the second storage tank and exchanging heat with the compressed energy storage system. By adopting such a setting, the system of the present invention can keep the heat exchange medium in a liquid state at all times, which can not only greatly improve the heat exchange efficiency, but also select a medium with a lower boiling point as the heat exchange medium, such as softened water, which greatly reduces the cost and construction cost of the heat recovery system. At the same time, it is more convenient to replace or supplement a new heat exchange medium in the later stage, which has better economy and is conducive to the implementation of the heat recovery system in the field of compressed energy storage.

[0012] In combination with the first aspect, in a first implementation of the first aspect, the system further includes:

[0013] A booster pump, the booster pump is connected to the output end of the first storage tank through a first pipeline, and the booster pump is connected to the energy storage heat exchange side through a second pipeline;

[0014] The booster pump is adapted to adjust the pressure of the heat exchange medium flowing out of the first storage tank to exceed the first preset pressure.

[0015] The heat recovery system provided in the embodiment of the present invention can increase the pressure of the heat exchange medium to a pressure exceeding the first preset pressure through the setting of a booster pump. When the boosted heat exchange medium recovers heat energy, it will not be vaporized and can still maintain a liquid state, which can greatly improve the heat exchange efficiency. Therefore, a medium with a lower boiling point can be selected as the heat exchange medium. After adopting the booster pump, the pipeline connecting the first storage tank and the energy storage heat exchange side can also be reduced in grade. The first pipeline connecting the first storage tank and the booster pump is made of a cheaper conventional material with normal temperature and pressure properties. Only the second pipeline connecting the booster pump and the energy storage heat exchange side needs to be made of a more expensive high temperature and high pressure resistant material, thereby further reducing the cost and construction cost of the heat recovery system.

[0016] In combination with the first aspect, in a second implementation of the first aspect, the system further includes:

[0017] The switch valve is arranged on a fourth pipeline connecting the first output end of the second storage tank and the energy release heat exchange side.

[0018] The heat energy recovery system provided in the embodiment of the present invention can control the flow and flow rate of the heat exchange medium from the second storage tank to the first storage tank during energy release by setting the switch valve.

[0019] In combination with the second implementation of the first aspect, in a third implementation of the first aspect, the system further includes:

[0020] An exhaust pump is arranged on a fifth pipeline connected to the first output end of the second storage tank and the switch valve.

[0021] The heat recovery system provided in an embodiment of the present invention, before starting, first fills the second storage tank with heat exchange medium at normal temperature and pressure, empties the air in the second storage tank, then opens the switch valve, and uses the exhaust pump to transport all the heat exchange medium at normal temperature and pressure in the second storage tank to the first storage tank. The transportation process can empty the air in the fourth, fifth, sixth pipelines and the first storage tank. Through the above preparatory work before starting, the air in the heat recovery system can be completely emptied, thereby ensuring that there is no oxygen involved in the operation, and preventing various equipment and pipelines from being subjected to high-temperature oxidation corrosion.

[0022] In combination with the third implementation of the first aspect, in the fourth implementation of the first aspect, the system further includes:

[0023] A pressure reducing valve is arranged on a sixth pipeline connecting the input end of the first storage tank and the energy releasing heat exchanging side.

[0024] The heat recovery system provided in the embodiment of the present invention can ensure that the pressure of the heat exchange medium entering the first storage tank is close to normal pressure through the setting of the pressure reducing valve. Therefore, it is further ensured that the preparation material of the first storage tank can be a conventional material with normal temperature and normal pressure properties, thereby reducing the cost and construction price of the heat recovery system.

[0025] In combination with the first aspect, in a fifth implementation of the first aspect, the pressure maintaining mechanism includes:

[0026] A nitrogen storage tank, used to store nitrogen, the nitrogen storage tank comprising a maintenance inlet and a maintenance outlet;

[0027] The maintenance inlet is connected to the first output end of the second storage tank through a seventh pipeline, and a nitrogen compressor is provided on the seventh pipeline;

[0028] The maintenance outlet is connected to the first input end of the second storage tank through an eighth pipeline, and a nitrogen expander is provided on the eighth pipeline.

[0029] The heat energy recovery system provided in the embodiment of the present invention stores and releases energy synchronously with the compression energy storage system through a pressure maintaining mechanism, which not only improves the system capacity, but also ensures that the pressure and temperature in the second storage tank meet the design requirements, thereby ensuring that the heat exchange medium in the second storage tank always remains in a liquid state.

[0030] According to a second aspect, an embodiment of the present invention provides a compressed energy storage system, the system comprising:

[0031] An energy storage subsystem having an energy storage and heat exchange side;

[0032] An energy release subsystem having an energy release heat exchange side;

[0033] The heat energy recovery system described in any one of the above is suitable for exchanging heat energy with the energy storage heat exchange side and the energy release heat exchange side.

[0034] The compressed energy storage system of the present invention recovers and replenishes heat energy through a heat recovery system, and cooperates with the energy storage process and the energy release process to reciprocate to achieve time difference matching between power generation and power consumption.

[0035] According to a third aspect, an embodiment of the present invention provides a heat energy recovery method, comprising:

[0036] When the compressed energy storage system stores energy, the heat exchange medium stored in the first storage tank flows out, and after being pressurized to exceed the first preset pressure, exchanges heat energy with the energy storage heat exchange side of the compressed energy storage system, and flows into the second storage tank for storage;

[0037] When the compressed energy storage system releases energy, the heat exchange medium stored in the second storage tank flows out, exchanges heat energy with the energy release heat exchange side of the compressed energy storage system, and flows into the first storage tank for storage.

[0038] In the heat recovery method provided by the embodiment of the present invention, since the heat exchange medium will be pressurized to exceed the first preset pressure before exchanging heat with the energy storage heat exchange side of the energy storage subsystem, the heat exchange medium is kept in liquid form when storing in the first storage tank and the second storage tank and exchanging heat with the compressed energy storage system. By adopting such a setting, the method of the present invention can keep the heat exchange medium in a liquid state at all times, which can not only greatly improve the heat exchange efficiency, but also select a medium with a lower boiling point as the heat exchange medium, such as softened water, which greatly reduces the cost and construction cost of the heat recovery system. At the same time, it is more convenient to replace or supplement a new heat exchange medium in the later stage, which has better economy and is conducive to the implementation of the heat recovery system in the field of compressed energy storage.

[0039] In conjunction with the third aspect, in a first implementation of the third aspect, the method further includes:

[0040] When the compression energy storage system stores energy, the nitrogen in the second storage tank is compressed and passed into the nitrogen storage tank through the nitrogen compressor, so that the pressure in the second storage tank exceeds the first preset pressure and does not exceed the second preset pressure; the second preset pressure exceeds the first preset pressure;

[0041] When the compressed energy storage system releases energy, the nitrogen in the nitrogen storage tank is expanded and passed into the second storage tank through the nitrogen expander, so that the pressure in the second storage tank exceeds the first preset pressure and does not exceed the second preset pressure.

[0042] The heat energy recovery method provided in the embodiment of the present invention stores and releases energy synchronously with the compression energy storage system through the pressure maintaining mechanism, which not only improves the system capacity, but also ensures that the pressure and temperature in the second storage tank meet the design requirements, thereby ensuring that the heat exchange medium in the second storage tank always remains in a liquid state.

[0043] In combination with the third aspect, in a second implementation manner of the third aspect, before exchanging heat energy with the compressed energy storage system, the method further includes:

[0044] The switch valve is closed, and the heat exchange medium at normal temperature and pressure is introduced into the second storage tank until the second storage tank is full;

[0045] Opening the switch valve, using the exhaust pump to discharge the heat exchange medium stored in the second storage tank into the first storage tank, and using the nitrogen expander to inject nitrogen into the second storage tank until the heat exchange medium in the second storage tank is emptied;

[0046] The second storage tank is filled with nitrogen through the nitrogen expander, and the pressure in the second storage tank exceeds the first preset pressure and does not exceed the second preset pressure.

[0047] The heat recovery method provided in the embodiment of the present invention can achieve complete exhaustion of air in the heat recovery system, thereby ensuring that there is no oxygen involved in the operation and preventing various equipment and pipelines from being subjected to high-temperature oxidation corrosion. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0049] Figure 1 A schematic diagram of the structure of a heat recovery system provided by an embodiment of the present invention is shown;

[0050] Figure 2 It shows a schematic structural diagram of a pressure maintaining mechanism in a heat energy recovery system provided in an embodiment of the present invention;

[0051] Figure 3 A schematic structural diagram of a compressed energy storage system provided by an embodiment of the present invention is shown;

[0052] Figure 4 One of the schematic flow diagrams of the heat energy recovery method provided by an embodiment of the present invention is shown;

[0053] Figure 5 The second schematic flow chart of the heat energy recovery method provided by the embodiment of the present invention is shown;

[0054] Figure 6 The third flow chart of the heat energy recovery method provided by the embodiment of the present invention is shown;

[0055] Figure 7 A schematic diagram of an electronic device provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0057] A large amount of compression heat will be generated during the compression energy storage process. If this part of the compression heat is not recycled, it will seriously affect the operating efficiency of the entire compression energy storage system. To recover this part of high-quality compression heat, it is necessary to use heat transfer oil with a high boiling point as a heat exchange medium. However, the cost of using and replacing heat transfer oil is very high, which greatly affects the technical and economic feasibility of the technology. Specifically:

[0058] At present, whether it is a gas-liquid or liquid-liquid conversion compression energy storage system, there is a compression unit, such as a compressor, and the gas temperature at the compressor outlet is basically far more than 100°C, up to 220-270°C. Therefore, if this part of the compressed heat energy is to be stored as high-quality heat energy, the existing technology needs to use heat transfer oil with a higher boiling point as a heat recovery medium, and the heat recovery system of the compressed energy storage requires a very large amount of heat transfer oil, and the heat transfer oil needs to be replaced after long-term use. Therefore, the heat recovery system in the existing technology uses heat transfer oil with a huge investment cost, resulting in a high cost of energy storage technology landing.

[0059] Combine the following Figure 1 The heat recovery system of the present invention is described, the system comprising:

[0060] The first storage tank 101 and the second storage tank 102, the first storage tank is used to store the heat exchange medium at normal pressure, and the second storage tank is used to store the heat exchange medium exceeding the first preset pressure.

[0061] The first preset pressure is the saturation pressure corresponding to the maximum heating temperature of the compressed energy storage system during energy storage, and the maximum heating temperature is the gas temperature at the outlet of the compression unit on the energy storage heat exchange side, such as the gas temperature at the outlet of the compressor. In this embodiment, normal pressure refers to the pressure of one atmosphere, and the first preset pressure is a high pressure relative to normal pressure.

[0062] After the heat exchange medium flowing out of the first storage tank 101 is pressurized and exceeds the first preset pressure, it exchanges heat energy with the energy storage heat exchange side (such as expansion devices such as heaters) of the compression energy storage system. At this time, the heat exchange medium is used to recover the heat energy of the energy storage heat exchange side. The temperature of the heat exchange medium increases. After the recovery is completed, the heat exchange medium flows into the second storage tank 102 for storage. Therefore, the heat exchange medium stored in the second storage tank 102 is high-temperature and high-pressure heat exchange medium.

[0063] It should be noted that the energy storage and heat exchange side of the compression energy storage system can adopt a multi-stage setting, and each stage is composed of a corresponding compression unit and a cooling unit. Preferably, the compression unit can be a compressor, and the cooling unit can be a cooler; the energy release and heat exchange side of the compression energy storage system can also adopt a multi-stage setting, and each stage is composed of a corresponding heating unit and an expansion unit. Preferably, the heating unit can be a heater, and the expansion unit can be a turbine.

[0064] The heat exchange medium stored in the second storage tank 102 is kept above the first preset pressure by the pressure maintaining mechanism. The heat exchange medium flowing out of the second storage tank 102 exchanges heat energy with the energy release heat exchange side of the compressed energy storage system. At this time, the heat exchange medium is used to increase the temperature of the energy release heat exchange side, that is, to heat the air or carbon dioxide on the energy release heat exchange side to increase the work capacity of the air or carbon dioxide. The temperature of the heat exchange medium decreases, and after the energy supply is completed, the heat exchange medium flows into the first storage tank 101 for storage.

[0065] In order to obtain a sufficiently high heat exchange efficiency, the heat exchange medium currently used in the compressed energy storage system is generally a liquid medium at normal temperature and pressure. In the system of the present invention, since the heat exchange medium will be pressurized to exceed the first preset pressure before exchanging heat with the energy storage heat exchange side of the energy storage subsystem, it maintains a liquid state when storing in the first storage tank 101 and the second storage tank 102 and exchanging heat with the compressed energy storage system. By adopting such a setting, the system of the present invention can keep the heat exchange medium in a liquid state at all times, which can not only greatly improve the heat exchange efficiency, but also select a medium with a lower boiling point as the heat exchange medium, such as softened water, which greatly reduces the cost and construction cost of the heat recovery system. At the same time, it is more convenient to replace or supplement new heat exchange media in the later stage, which has better economy and is conducive to the implementation of the heat recovery system in the field of compressed energy storage.

[0066] In the existing compressed energy storage system, since the heat exchange medium needs to exchange heat with the compressed energy storage system, two storage tanks with high pressure resistance or other devices suitable for storing high temperature and high pressure fluid media are required. As some possible embodiments of the present invention, by increasing the heat exchange medium flowing out of the first storage tank 101 to a pressure exceeding the first preset pressure and the setting of the pressure maintaining mechanism 103, only the second storage tank 102 needs to be made of a material with high temperature and high pressure resistance, while the first storage tank 101 can be made of a cheaper conventional material with normal temperature (or normal temperature range, such as 0-70°C) and normal pressure properties, further reducing the cost and construction cost of the heat recovery system.

[0067] In the existing compressed energy storage system, the temperature of the heat exchange medium will rise rapidly when recovering the heat of the compressed energy storage system, so the pipelines in the entire heat recovery system need to be made of high temperature and high pressure resistant materials. As some possible embodiments of the present invention, by increasing the heat exchange medium flowing out of the first storage tank 101 to a pressure exceeding the first preset pressure, the setting of the pressure maintaining mechanism 103, and the first storage tank 101 can be made of conventional materials, the part of the pipeline connecting the first storage tank 101 with the energy storage and release heat exchange sides can also be made of cheaper conventional materials of normal temperature and pressure properties, and similarly, the cost and construction cost of the heat recovery system are further reduced.

[0068] Specifically, the heat recovery system of the present invention further includes:

[0069] A booster pump 104 is used to increase the pressure of the heat exchange medium. In this embodiment, the booster pump 104 is connected to the output end of the first storage tank 101 through a first pipeline, the booster pump 104 is connected to the energy storage heat exchange side through a second pipeline, and the energy storage heat exchange side is connected to the first input end of the second storage tank 102 through a third pipeline.

[0070] The specific working parameters of the booster pump 104 need to be set to be able to boost the pressure of the fluid medium to above the first preset pressure. Taking the maximum heating temperature of the compressed energy storage system as 250°C during energy storage as an example, the saturation pressure corresponding to the maximum heating temperature is 2MPa. The selection of the booster pump 104 needs to be able to boost the heat exchange medium to above 2MPa, that is, the booster pump 104 needs to be able to increase the pressure of the heat exchange medium to exceed the first preset pressure.

[0071] By setting up the booster pump 104, the heat exchange medium can be pressurized to exceed the first preset pressure. When the pressurized heat exchange medium recovers heat energy, it will not be vaporized and can still maintain a liquid state, which can greatly improve the heat exchange efficiency. Therefore, a medium with a lower boiling point can be selected as the heat exchange medium. After using the booster pump 104, the pipeline connecting the first storage tank 101 and the energy storage heat exchange side can also be reduced in grade. The first pipeline connecting the first storage tank 101 and the booster pump 104 is made of a cheaper conventional material with normal temperature and pressure properties. Only the second pipeline connecting the booster pump 104 and the energy storage heat exchange side needs to be made of a more expensive high temperature and high pressure resistant material, thereby further reducing the cost and construction cost of the heat recovery system.

[0072] In the heat energy recovery system of the present invention, after the heat energy of the compressed energy storage system is recovered, since the pressure in the second storage tank 102 is a high pressure and the pressure in the first storage tank 101 is a normal pressure, when the compressed energy storage system releases energy and needs the heat exchange medium to provide energy, the heat exchange medium in the second storage tank 102 can enter the first storage tank 101 through the pressure difference between the two tanks, and no additional power pump is required to transport the heat storage medium.

[0073] Specifically, the system further includes:

[0074] The switch valve 105 is arranged on the fourth pipeline connecting the first output end of the second storage tank 102 and the energy release heat exchange side, and the energy release heat exchange side is connected to the input end of the first storage tank 101 through the sixth pipeline.

[0075] By setting the switch valve 105, the user can control the flow and flow rate of the heat exchange medium from the second storage tank 102 to the first storage tank 101 during energy release.

[0076] Specifically, the system further includes:

[0077] The exhaust pump 106 is disposed on a fifth pipeline connected to the first output end of the second storage tank 102 and the switch valve 105 .

[0078] In the heat recovery system of the present invention, a branch connected between the switch valve 105 and the first output end of the second storage tank 102, namely the fifth pipeline, is provided beside the fourth pipeline, and an exhaust pump 106 for discharging the gas and heat exchange medium in the second storage tank 102 is also provided on the fifth pipeline.

[0079] Before starting the heat recovery system of the present invention, first fill the second storage tank 102 with heat exchange medium at normal temperature and pressure, exhaust the air in the second storage tank 102, then open the switch valve 105, and use the exhaust pump 106 to transport all the heat exchange medium at normal temperature and pressure in the second storage tank 102 to the first storage tank 101. The transportation process can exhaust the air in the fourth, fifth, sixth pipelines and the first storage tank 101. Through the above preparatory work before starting, the air in the heat recovery system can be completely exhausted, thereby ensuring that there is no oxygen involved in the operation and preventing various equipment and pipelines from being subjected to high-temperature oxidation corrosion.

[0080] It can be understood that the effective capacity of the second storage tank 102 is not less than the effective capacity of the first storage tank 101 .

[0081] Specifically, the system further includes:

[0082] The pressure reducing valve 107 is arranged on the sixth pipeline connecting the input end of the first storage tank 101 and the energy release and heat exchange side.

[0083] By setting the pressure reducing valve 107, it can be ensured that the pressure of the heat exchange medium entering the first storage tank 101 is close to normal pressure. Therefore, it is further ensured that the material prepared by the first storage tank 101 can be a conventional material with normal temperature and pressure properties, thereby reducing the cost and construction cost of the heat recovery system.

[0084] Combine the following Figure 2 The heat recovery system of the present invention is described, and the pressure maintaining mechanism 103 in the system comprises:

[0085] The nitrogen storage tank 1031 is used to store nitrogen, and includes a maintenance inlet and a maintenance outlet. The maintenance inlet is connected to the first output end of the second storage tank 102 through the seventh pipeline, and a nitrogen compressor 1032 is provided on the seventh pipeline; the maintenance outlet is connected to the first input end of the second storage tank 102 through the eighth pipeline, and a nitrogen expander 1033 is provided on the eighth pipeline.

[0086] During the system startup preparation process, nitrogen is charged into the second storage tank 102 through the nitrogen expander 1033 provided on the eighth pipeline to maintain the pressure in the second storage tank 102 stable. When the heat recovery system of the present invention continuously recovers the heat energy on the energy storage and heat exchange side, the heat exchange medium at normal temperature and pressure in the first storage tank 101 enters the second storage tank 102 after heat exchange and occupies the internal space of the second storage tank 102, so that the pressure in the second storage tank 102 increases. At this time, the nitrogen compressor 1032 provided on the seventh pipeline can be turned on, and the nitrogen in the second storage tank 102 is compressed into the nitrogen storage tank 1031 by the nitrogen compressor 1032. When the heat energy recovery system of the present invention provides previously stored heat energy to the energy releasing heat exchange side, the high temperature and high pressure heat exchange medium in the second storage tank 102 is extracted to heat the air or carbon dioxide on the energy releasing heat exchange side. Since the heat exchange medium continuously flows out of the second storage tank 102, the temperature in the second storage tank 102 decreases, and the pressure also decreases accordingly. At this time, the nitrogen expander 1033 arranged on the four pipelines is turned on, and the high pressure nitrogen stored in the nitrogen storage tank 1031 enters the nitrogen expander 1033 to do work and reduce the pressure, and then the nitrogen enters the second storage tank 102 to maintain the pressure of the second storage tank 102.

[0087] In this embodiment, in order to enable the nitrogen compressor 1032 and the nitrogen expander 1033 to work stably and play a role in regulating the pressure, the pressure of the nitrogen storage tank 1031 is 5-7 times the pressure in the second storage tank 102.

[0088] It should be noted that the nitrogen expander 1033 needs to ensure that the pressure of the nitrogen entering the second storage tank 102 is always higher than the vaporization pressure of the heat exchange medium in the second storage tank 102, so as to ensure the pressure in the second storage tank 102 is stable, so that the heat exchange medium in the second storage tank 102 always remains in liquid state.

[0089] By synchronously storing and releasing energy with the compression energy storage system through the pressure maintaining mechanism 103, the system capacity is improved, and the pressure and temperature in the second storage tank 102 are guaranteed to meet the design requirements, thereby ensuring that the heat exchange medium in the second storage tank 102 is always kept in liquid state.

[0090] Combine the following Figure 3 The compressed energy storage system of the present invention is described, the system comprising:

[0091] The energy storage subsystem has an energy storage heat exchange side; the energy release subsystem has an energy release heat exchange side; the above-mentioned heat energy recovery system of the present invention is suitable for exchanging heat energy with the energy storage heat exchange side and the energy release heat exchange side.

[0092] The present invention is described by taking compressed carbon dioxide energy storage as an example. The compressed energy storage system of the present invention specifically includes:

[0093] A third storage tank 201; a second compressor 202 for compressing and storing energy, the third storage tank 201 is connected to the second compressor 202; a first cooler 203 for heat exchange, the second compressor 202 is connected to the first cooler 203; a third compressor 204 for compressing and storing energy, the first cooler 203 is connected to the third compressor 204; a second cooler 205 for heat exchange, the third compressor 204 is connected to the second cooler 205; a fourth storage tank 206, connected to the second cooler 205; a third storage tank 207 for heat exchange a first heater 207, the fourth storage tank 206 is connected to the first heater 207; a first turbine 208 for releasing energy, the first heater 207 is connected to the first turbine 208; a second heater 209 for heat exchange, the first turbine 208 is connected to the second heater 209; a second turbine 210 for releasing energy, the second heater 209 is connected to the second turbine 210; a fluid cooler 211 for cooling carbon dioxide is arranged between the second turbine 210 and the third storage tank 201.

[0094] Among them, the third storage tank 201, the second compressor 202, the first cooler 203, the third compressor 204, the second cooler 205 and the fourth storage tank 206 constitute the energy storage subsystem in the compression energy storage system of the present invention; the fourth storage tank 206, the first heater 207, the first turbine 208, the second heater 209, the second turbine 210, the fluid cooler 211 and the third storage tank 201 constitute the energy release subsystem in the compression energy storage system of the present invention.

[0095] In some possible embodiments of the present invention, both the energy storage and release heat exchange sides can be set as multi-stage equipment, and each stage of the energy storage heat exchange side includes a matching compression unit (for example, the second compressor 202, the third compressor 204, etc.) and a cooling unit (for example, the first cooler 203, the second cooler 205, etc.), and the second pipeline is connected to the heat exchange input end of the cooling unit, and the third pipeline is connected to the heat exchange output end of the cooling unit. Each stage of the energy release heat exchange side includes a matching expansion unit (for example, the second compressor 202, the third compressor 204, etc.) and a heating unit (for example, the first cooler 203, the second cooler 205, etc.), and the fourth pipeline is connected to the heat exchange input end of the heating unit, and the sixth pipeline is connected to the heat exchange output end of the heating unit.

[0096] During energy storage, the carbon dioxide from the third storage tank 201 enters the second compressor 202 in gaseous or liquid form and is compressed to increase its temperature and pressure. The high-temperature carbon dioxide at the outlet of the second compressor 202 enters the first cooler 203 to exchange heat with the heat exchange medium. The gaseous or supercritical carbon dioxide is cooled and then enters the third compressor 204 for compression again. The high-temperature carbon dioxide at the outlet of the third compressor 204 enters the first cooler 205 to exchange heat with the heat exchange medium. The cooled carbon dioxide is stored in the fourth storage tank 206 in gaseous or liquid form. During energy release, the carbon dioxide in the fourth storage tank 206 is first sent to the first heater 207 to exchange heat with the heat exchange medium and is heated. Then, it enters the first turbine 208 to expand and do work. The gaseous or supercritical carbon dioxide at the outlet of the first turbine 208 enters the second heater 209 to exchange heat with the heat exchange medium. After being heated, the carbon dioxide enters the second turbine 210 to expand and do work. The gaseous or supercritical carbon dioxide at the outlet of the second turbine 210 is cooled by the fluid cooler 211 and then stored in the third storage tank 201.

[0097] As an optional implementation manner of an embodiment of the present invention, a control valve suitable for controlling the flow of fluid can be set on the pipelines connecting the third storage tank 201 to the second compressor 202, the second compressor 202 to the first cooler 203, the first cooler 203 to the third compressor 204, the third compressor 204 to the second cooler 205, and the second cooler 205 to the fourth storage tank 206. A control valve suitable for controlling the flow of fluid can also be set on the pipelines connecting the fourth storage tank 206 to the first heater 207, the first heater 207 to the first turbine 208, the first turbine 208 to the second heater 209, the second heater 209 to the second turbine 210, the second turbine 210 to the fluid cooler 211, and the fluid cooler 211 to the third storage tank 201.

[0098] As an optional implementation of the embodiment of the present invention, the fluid cooler 211 can be a cooling device such as a condenser or a cooler.

[0099] When the user is in the low electricity consumption period, the control valves in the energy storage subsystem of the compression energy storage system, that is, the control valves on the pipelines connecting the third storage tank 201 to the second compressor 202, the second compressor 202 to the first cooler 203, the first cooler 203 to the third compressor 204, the third compressor 204 to the second cooler 205, and the second cooler 205 to the fourth storage tank 206, are opened, and the remaining control valves are closed, and the energy storage subsystem starts to work. The low-pressure carbon dioxide flows from the third storage tank 201 to the second compressor 202 to complete the first compression process, and is accompanied by the temperature rise of the carbon dioxide. After exchanging heat energy with the high-pressure and normal-temperature heat exchange medium provided by the first storage tank 101 through the first cooler 203, it flows into the third compressor 204 to complete the second compression process, and is accompanied by the temperature rise of the carbon dioxide. It exchanges heat energy with the high-pressure and low-temperature heat exchange medium through the second cooler 205. The cooled carbon dioxide is stored in the fourth storage tank 206 in a high-pressure liquid or supercritical state. At this time, the high-pressure and low-temperature heat exchange medium obtains the heat energy provided by the carbon dioxide and becomes a high-pressure and high-temperature heat exchange medium and is stored in the second storage tank 102.

[0100] When the user is at the peak of electricity consumption, the control valves in the energy release subsystem of the compressed energy storage system, i.e., the control valves on the pipelines connecting the fourth storage tank 206 and the first heater 207, the first heater 207 to the first turbine 208, the first turbine 208 to the second heater 209, the second heater 209 to the second turbine 210, the second turbine 210 to the fluid cooler 211, and the fluid cooler 211 to the third storage tank 201, are opened, and the other control valves are closed, and the energy release subsystem starts to work. After the high-pressure carbon dioxide flows from the fourth storage tank 206 through the first heater 207 to obtain heat energy, it flows to the first turbine 208 to complete the expansion process and generate electricity for the user, then flows through the second heater 209 to obtain heat energy, flows to the second turbine 210 to complete the expansion process and generate electricity for the user, and finally enters the third storage tank 201 for storage after being cooled by the fluid cooler 211. At this time, the high-pressure and high-temperature heat exchange medium in the second storage tank 102 is converted into a high-pressure and low-temperature heat exchange medium at the first heater 207 and the second heater 208 due to the supply of heat energy to carbon dioxide, and becomes a high-pressure and normal-temperature or high-pressure and low-temperature heat exchange medium, and then directly stored in the first storage tank 101 or stored in the first storage tank 101 after being decompressed.

[0101] In this embodiment, taking softened water as the heat exchange medium, high temperature refers to a temperature exceeding 100° C., and low temperature refers to a temperature between room temperature and 100° C. After heat exchange with the first heater 207 and the second heater 208, the temperature of the heat exchange medium is cooled to 50-60° C., and then stored in the first storage tank 101 to cool to room temperature, or stored in the first storage tank 101 after being reduced in pressure and temperature by the pressure reducing valve 107.

[0102] The energy storage process and the energy release process of the compression energy storage system of the present invention run reciprocatingly to achieve time difference matching between power generation and power consumption.

[0103] Combine the following Figure 4 The heat recovery method of the present invention is described. The method is implemented based on the heat recovery system of the present invention. The method comprises:

[0104] S14. When the compression energy storage system stores energy, the heat exchange medium stored in the first storage tank 101 flows out, and after being pressurized to exceed the first preset pressure, it exchanges heat energy with the energy storage heat exchange side of the compression energy storage system. After heat exchange, the heat exchange medium flows into the second storage tank 102 for storage.

[0105] S16. When the compressed energy storage system releases energy, the heat exchange medium stored in the second storage tank 102 flows out and exchanges heat energy with the energy release heat exchange side of the compressed energy storage system. After the heat exchange, the heat exchange medium flows into the first storage tank 101 for storage.

[0106] In the heat energy recovery method provided by the embodiment of the present invention, since the heat exchange medium will be pressurized to exceed the first preset pressure before exchanging heat with the energy storage heat exchange side of the energy storage subsystem, the heat exchange medium remains in liquid form when storing in the first storage tank 101 and the second storage tank 102 and exchanging heat with the compressed energy storage system. By adopting such a setting, the heat exchange medium can be kept in a liquid state at all times, which can not only greatly improve the heat exchange efficiency, but also select a medium with a lower boiling point as the heat exchange medium, such as softened water, to greatly reduce the cost and construction cost of the heat recovery system. At the same time, it is more convenient to replace or supplement new heat exchange media in the later stage, which has better economy and is conducive to the implementation of the heat recovery system in the field of compressed energy storage.

[0107] Combine the following Figure 5 The heat recovery method of the present invention is described, the method also comprising:

[0108] S15. When the compression energy storage system stores energy, the nitrogen in the second storage tank 102 is compressed and passed into the nitrogen storage tank 1031 through the nitrogen compressor 1032, so that the pressure in the second storage tank 102 exceeds the first preset pressure and does not exceed the second preset pressure. The second preset pressure exceeds the first preset pressure. The second preset pressure is the maximum safe storage pressure of the second storage tank 102, which is determined by the material used to make the second storage tank 102.

[0109] S17. When the compressed energy storage system releases energy, the nitrogen in the nitrogen storage tank 1031 is expanded and passed into the second storage tank 102 through the nitrogen expander 1033, so that the pressure in the second storage tank 102 exceeds the first preset pressure and does not exceed the second preset pressure.

[0110] The pressure maintaining mechanism 103 stores and releases energy synchronously with the compressed energy storage system, which not only increases the system capacity, but also ensures that the pressure and temperature in the second storage tank 102 meet the design requirements, thereby ensuring that the heat exchange medium in the second storage tank 102 always remains in liquid state.

[0111] Combine the following Figure 6 The heat recovery method of the present invention is described. Before exchanging heat energy with the compressed energy storage system, the method further comprises:

[0112] S11, closing the switch valve 105, and introducing a heat exchange medium at normal temperature and pressure into the second storage tank 102 until the second storage tank 102 is full.

[0113] S12, open the switch valve 105, use the exhaust pump 106 to discharge the heat exchange medium stored in the second storage tank 102 into the first storage tank 101, and use the nitrogen expander 1033 to inject nitrogen into the second storage tank 102 until the heat exchange medium in the second storage tank 102 is emptied.

[0114] While transporting the heat exchange medium, nitrogen is injected by the nitrogen expander 1033 to maintain the pressure in the second storage tank 102 not too low, so as to avoid deformation or damage of the second storage tank 102 due to excessively low internal pressure, such as vacuum loss.

[0115] S13. Fill the second storage tank 102 with nitrogen through the nitrogen expander 1033, and make the pressure in the second storage tank 102 exceed the first preset pressure and do not exceed the second preset pressure.

[0116] Steps S11 to S13 are preparations before starting the heat recovery system. Through steps S11 to S13, the air in the heat recovery system can be completely exhausted, thereby ensuring that there is no oxygen involved in the operation and preventing various equipment and pipelines from being subjected to high-temperature oxidation corrosion.

[0117] Figure 7 An example of a physical structure diagram of an electronic device is shown in FIG. Figure 7 As shown, the electronic device may include: a processor 310, a communication interface 320, a memory 330 and a communication bus 340, wherein the processor 310, the communication interface 320 and the memory 330 communicate with each other through the communication bus 340. The processor 310 may call the logic command in the memory 330 to execute the heat energy recovery method, which includes:

[0118] When the compressed energy storage system stores energy, the heat exchange medium stored in the first storage tank flows out, and after being pressurized to exceed the first preset pressure, exchanges heat energy with the energy storage heat exchange side of the compressed energy storage system, and flows into the second storage tank for storage;

[0119] When the compressed energy storage system releases energy, the heat exchange medium stored in the second storage tank flows out, exchanges heat energy with the energy release heat exchange side of the compressed energy storage system, and flows into the first storage tank for storage.

[0120] In addition, the logic commands in the above-mentioned memory 330 can be implemented in the form of software functional units and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several commands to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a disk or an optical disk.

[0121] On the other hand, the present invention further provides a computer program product, the computer program product comprising a computer program, the computer program can be stored in a non-transitory computer-readable storage medium, when the computer program is executed by a processor, the computer can execute the heat energy recovery method provided by the above methods, the method comprising:

[0122] When the compressed energy storage system stores energy, the heat exchange medium stored in the first storage tank flows out, and after being pressurized to exceed the first preset pressure, exchanges heat energy with the energy storage heat exchange side of the compressed energy storage system, and flows into the second storage tank for storage;

[0123] When the compressed energy storage system releases energy, the heat exchange medium stored in the second storage tank flows out, exchanges heat energy with the energy release heat exchange side of the compressed energy storage system, and flows into the first storage tank for storage.

[0124] In another aspect, the present invention further provides a non-transitory computer-readable storage medium having a computer program stored thereon, which is implemented when the computer program is executed by a processor to perform the heat energy recovery method provided by the above methods, the method comprising:

[0125] When the compressed energy storage system stores energy, the heat exchange medium stored in the first storage tank flows out, and after being pressurized to exceed the first preset pressure, exchanges heat energy with the energy storage heat exchange side of the compressed energy storage system, and flows into the second storage tank for storage;

[0126] When the compressed energy storage system releases energy, the heat exchange medium stored in the second storage tank flows out, exchanges heat energy with the energy release heat exchange side of the compressed energy storage system, and flows into the first storage tank for storage.

[0127] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0128] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of commands to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A heat recovery system, characterized in that: The system comprises: a first storage tank and a second storage tank, wherein the first storage tank is used to store a heat exchange medium at normal pressure, and the second storage tank is used to store the heat exchange medium at a pressure exceeding a first preset pressure; the first preset pressure is a saturation pressure corresponding to the maximum heating temperature of the compressed energy storage system during energy storage; The heat exchange medium flowing out of the first storage tank exchanges heat energy with the energy storage heat exchange side of the compressed energy storage system after being pressurized to exceed the first preset pressure, and flows into the second storage tank for storage; the heat exchange medium stored in the second storage tank is kept at a pressure exceeding the first preset pressure by a pressure maintaining mechanism; The heat exchange medium flowing out of the second storage tank exchanges heat energy with the energy release heat exchange side of the compressed energy storage system and flows into the first storage tank for storage; The heat exchange medium remains in liquid form when stored in the first and second storage tanks and when exchanging heat energy with the compressed energy storage system.

2. The heat recovery system according to claim 1, characterized in that: The system also includes: A booster pump, the booster pump is connected to the output end of the first storage tank through a first pipeline, and the booster pump is connected to the energy storage heat exchange side through a second pipeline; The booster pump is adapted to adjust the pressure of the heat exchange medium flowing out of the first storage tank to exceed the first preset pressure.

3. The heat recovery system according to claim 1, characterized in that: The system also includes: The switch valve is arranged on a fourth pipeline connecting the first output end of the second storage tank and the energy release heat exchange side.

4. The heat recovery system according to claim 3, characterized in that: The system also includes: An exhaust pump is arranged on a fifth pipeline connected to the first output end of the second storage tank and the switch valve.

5. The heat recovery system according to claim 4, characterized in that: The system also includes: The pressure reducing valve is arranged on the sixth pipeline connecting the input end of the first storage tank and the energy releasing heat exchanging side.

6. The heat recovery system according to claim 1, characterized in that: The pressure maintaining mechanism comprises: A nitrogen storage tank, used to store nitrogen, the nitrogen storage tank comprising a maintenance inlet and a maintenance outlet; The maintenance inlet is connected to the first output end of the second storage tank through a seventh pipeline, and a nitrogen compressor is provided on the seventh pipeline; The maintenance outlet is connected to the first input end of the second storage tank through an eighth pipeline, and a nitrogen expander is provided on the eighth pipeline.

7. A compressed energy storage system, characterized in that: The system comprises: An energy storage subsystem having an energy storage and heat exchange side; An energy release subsystem having an energy release heat exchange side; The heat energy recovery system according to any one of claims 1 to 6, wherein the heat energy recovery system is suitable for exchanging heat energy with the energy storage heat exchange side and the energy release heat exchange side.

8. A heat recovery method implemented based on the heat recovery system according to any one of claims 1 to 6, characterized in that: include: When the compressed energy storage system stores energy, the heat exchange medium stored in the first storage tank flows out, and after being pressurized to exceed the first preset pressure, exchanges heat energy with the energy storage heat exchange side of the compressed energy storage system, and flows into the second storage tank for storage; When the compressed energy storage system releases energy, the heat exchange medium stored in the second storage tank flows out, exchanges heat energy with the energy release heat exchange side of the compressed energy storage system, and flows into the first storage tank for storage.

9. The heat recovery method according to claim 8, characterized in that: The pressure maintaining mechanism comprises: A nitrogen storage tank, used to store nitrogen, the nitrogen storage tank comprising a maintenance inlet and a maintenance outlet; The maintenance inlet is connected to the first output end of the second storage tank through a seventh pipeline, and a nitrogen compressor is provided on the seventh pipeline; The maintenance outlet is connected to the first input end of the second storage tank through an eighth pipeline, and a nitrogen expander is provided on the eighth pipeline; The method further includes: When the compression energy storage system stores energy, the nitrogen in the second storage tank is compressed and passed into the nitrogen storage tank through the nitrogen compressor, so that the pressure in the second storage tank exceeds the first preset pressure and does not exceed the second preset pressure; the second preset pressure exceeds the first preset pressure; When the compressed energy storage system releases energy, the nitrogen in the nitrogen storage tank is expanded and passed into the second storage tank through the nitrogen expander, so that the pressure in the second storage tank exceeds the first preset pressure and does not exceed the second preset pressure.

10. The heat recovery method according to claim 9, characterized in that: Also includes: A switch valve is arranged on a fourth pipeline connecting the first output end of the second storage tank and the energy release heat exchange side; An exhaust pump is provided on a fifth pipeline connected to the first output end of the second storage tank and the switch valve; Prior to exchanging thermal energy with the compressed energy storage system, the method further comprises: The switch valve is closed, and the heat exchange medium at normal temperature and pressure is introduced into the second storage tank until the second storage tank is full; Opening the switch valve, using the exhaust pump to discharge the heat exchange medium stored in the second storage tank into the first storage tank, and using the nitrogen expander to inject nitrogen into the second storage tank until the heat exchange medium in the second storage tank is emptied; The second storage tank is filled with nitrogen through the nitrogen expander, and the pressure in the second storage tank exceeds the first preset pressure and does not exceed the second preset pressure.

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