Compression working medium energy storage system and compression working medium energy storage method

Abstract

The invention provides a compressed working medium energy storage system and a compressed working medium energy storage method. The compressed working medium energy storage system comprises a first storage cavern, a second storage cavern, an energy storage module, an energy release module and a heat storage device. A shunting expansion loop is arranged in the energy storage module and used for cooling an energy storage working medium, and arrangement of an external cold source is avoided; the split-flow compression loop is arranged in the energy release module and used for heating the energy storage working medium, arrangement of an external heat source is avoided, in this way, the arrangement difficulty of the compressed working medium energy storage system is reduced, the split-flow expansion loop further has the effect of converting electric energy into heat energy, and the split-flow compression loop further has the effect of converting heat energy into electric energy; and the two functions jointly form an electric heating energy storage function, so that electric heating energy storage is added on the basis of compressed working medium energy storage, and the energy storage capacity of the system is expanded.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a compressed working fluid energy storage system and a compressed working fluid energy storage method. Background Art

[0002] Compressed working fluid energy storage is a new long-term and large-scale energy storage technology route with broad development prospects. The working fluids that have been put into engineering application include air and carbon dioxide. Since carbon dioxide can be easily cooled and liquefied or form a high-density supercritical state under high pressure, and vice versa, it can easily be heated and vaporized, which can solve the problem of flexible storage and call of working fluids. Therefore, compressed carbon dioxide energy storage has received widespread attention, and the industry has also begun to explore other working fluids with similar physical properties. However, the existing compressed working fluid energy storage system relies on external cold source and heat source conditions to realize the liquefaction and gasification of the working fluid respectively. The general plant site cannot meet the cold source and heat source conditions at the same time. If special heating or cooling facilities are built, the investment is large, the energy consumption is high, and the energy efficiency of the compressed working fluid energy storage system is seriously affected, and the economy is poor. Therefore, the above-mentioned cold and heat source problems cause great trouble to the layout of energy storage power stations. Summary of the invention

[0003] In view of this, the present application provides a compressed working fluid energy storage system, which avoids dependence on external cold source and external heat source conditions by setting a shunt expansion loop with electric-thermal conversion energy storage function in the energy storage module, and setting a shunt compression loop with thermal-electric conversion energy release function in the energy release module, thereby reducing the difficulty of arranging the compressed working fluid energy storage system and expanding the energy storage capacity of the system. In addition, the present application also provides a compressed working fluid energy storage method suitable for the above-mentioned compressed working fluid energy storage system.

[0004] In order to achieve the above objectives, this application provides the following technical solutions:

[0005] A compressed working fluid energy storage system, comprising:

[0006] A first reservoir, used for releasing gaseous energy storage medium;

[0007] A second reservoir, used to store the energy storage medium in a liquid or supercritical state;

[0008] The energy storage module comprises a first compressor, a second compressor, a first heat exchanger, a first heat exchange device, a second heat exchanger, a first expander, and a second expander; the first reservoir, the first compressor, the second compressor, the heat path of the first heat exchanger, the heat path of the first heat exchange device, the heat path of the second heat exchanger, the first expander, and the second reservoir are sequentially connected in series to form an energy storage flow path, so that the energy storage medium outputted from the first reservoir is compressed, cooled, and expanded in sequence, and the high-density energy storage medium is transported to the second reservoir, so as to realize the conversion of electrical energy into pressure energy and thermal energy and store them;

[0009] The second expander, the cold circuit of the second heat exchanger, the first cold circuit of the first heat exchange device, the second compressor, the hot circuit of the first heat exchanger, the hot circuit of the first heat exchange device and the second expander are sequentially connected in series to form a split expansion circuit, so that the energy storage medium flowing through the hot circuit of the first heat exchange device is split, and part of the energy storage medium is expanded and cooled by the second expander, and is heated by heat exchange with the hot circuit of the second heat exchanger and the hot circuit of the first heat exchange device, so as to cool the energy storage medium flowing through the hot circuit of the second heat exchanger and the hot circuit of the first heat exchange device;

[0010] The energy release module comprises a third compressor, a fourth compressor, a third heat exchanger, a second heat exchange device, a fourth heat exchanger, a third expander, a fourth expander and a fifth expander; the second reservoir, the third compressor, the cold circuit of the third heat exchanger, the cold circuit of the second heat exchange device, the cold circuit of the fourth heat exchanger, the third expander, the fourth expander, the first hot circuit of the third heat exchanger, the fifth expander and the first reservoir are sequentially connected in series to form an energy release flow path, so that the energy storage working fluid output from the second reservoir is compressed, heated and expanded in sequence to drive the third expander, the fourth expander and the fifth expander to generate electricity to realize energy release, and at the same time, the energy storage working fluid is transported to the first reservoir;

[0011] The first heat path of the second heat exchange device, the second heat path of the third heat exchanger and the fourth compressor, the cold path of the second heat exchange device, the cold path of the fourth heat exchanger, the third expander and the first heat path of the second heat exchange device are sequentially connected in series to form a split compression circuit, so that the energy storage working medium is split after being expanded by the third expander, and part of the energy storage working medium releases residual heat to the energy storage working medium flowing through the cold path of the second heat exchange device and the cold path of the third heat exchanger in sequence through the first heat path of the second heat exchange device and the second heat path of the third heat exchanger;

[0012] A heat storage device is connected between the energy storage module and the energy release module and has a heat storage stage and a heat release stage, so that when the energy storage stage is in the heat storage stage, the energy storage working fluid of the bypass expansion circuit merges with the energy storage working fluid of the energy release flow path at the inlet of the second compressor, and converts the compression heat of the second compressor into the thermal energy of the heat storage device through the thermal path of the first heat exchanger and the thermal path of the first heat exchange device; when the energy release stage is in the heat release stage, the energy storage working fluid exchanges heat with the second thermal path of the second heat exchange device and the thermal path of the fourth heat exchanger to increase the temperature, so as to convert the thermal energy stored in the heat storage device into electrical energy through the third expander, the fourth expander and the fifth expander.

[0013] Optionally, in the above-mentioned compressed working fluid energy storage system, the heat storage device includes a first heat storage device and a heat storage device group, and the first heat storage device and the heat storage device group both store heat storage medium;

[0014] The first heat storage device is connected to the cold circuit of the first heat exchanger and the hot circuit of the fourth heat exchanger, and the heat storage device group is connected to the second cold circuit of the first heat exchange device and the second hot circuit of the second heat exchange device, so that the electrical energy is converted into the thermal energy in the heat storage medium in the energy storage stage, and the thermal energy in the heat storage medium is converted into electrical energy in the energy release stage.

[0015] Optionally, in the above-mentioned compressed working fluid energy storage system, the heat storage device includes at least two heat storage devices;

[0016] The first heat exchange device and the second heat exchange device each include at least two heat exchangers, the heat exchanger of the first heat exchange device and the heat exchanger of the second heat exchange device are arranged in a one-to-one correspondence, and one of the heat storage devices is connected between the two corresponding heat exchangers of the first heat exchange device and the second heat exchange device.

[0017] Optionally, in the above-mentioned compressed working fluid energy storage system, the first heat exchange device includes a fifth heat exchanger and a sixth heat exchanger;

[0018] The second heat exchange device includes a seventh heat exchanger and an eighth heat exchanger;

[0019] The heat storage device group includes a second heat storage device and a third heat storage device, the second heat storage device is connected to the second cold circuit of the fifth heat exchanger and the second hot circuit of the eighth heat exchanger, and the third heat storage device is connected to the second cold circuit of the sixth heat exchanger and the second hot circuit of the seventh heat exchanger.

[0020] Optionally, in the above-mentioned compressed working fluid energy storage system, the first heat storage device includes a first cold tank and a first hot tank, and the first heat storage device stores a first heat storage medium;

[0021] The second heat storage device comprises a second cold tank and a second hot tank, and the second heat storage device stores a second heat storage medium;

[0022] The third heat storage device comprises a third cold tank and a third hot tank, and the third heat storage device stores a third heat storage medium;

[0023] Among them, in the energy storage stage, the first heat storage medium flows out from the first cold tank and enters the first hot tank after heat exchange and temperature increase with the first heat exchanger, the second heat storage medium flows out from the second cold tank and enters the second hot tank after heat exchange and temperature increase with the fifth heat exchanger, and the third heat storage medium flows out from the third cold tank and enters the third hot tank after heat exchange and temperature increase with the sixth heat exchanger; in the energy release stage, the first heat storage medium flows out from the first hot tank and enters the first cold tank after heat exchange and temperature reduction with the fifth heat exchanger, the second heat storage medium flows out from the second hot tank and enters the second cold tank after heat exchange and temperature reduction with the eighth heat exchanger, and the third heat storage medium flows out from the third hot tank and enters the third cold tank after heat exchange and temperature reduction with the seventh heat exchanger.

[0024] Optionally, in the above-mentioned compressed working fluid energy storage system, the working temperature of the first heat storage medium>the working temperature of the second heat storage medium>the working temperature of the third heat storage medium.

[0025] Optionally, in the above-mentioned compressed working fluid energy storage system, the first heat storage medium is molten salt;

[0026] The second heat storage medium and the third heat storage medium are both water.

[0027] Optionally, in the above-mentioned compressed working fluid energy storage system, the energy storage working fluid is carbon dioxide.

[0028] A compressed working fluid energy storage method, which uses the compressed working fluid energy storage system as described in any one of the above, and the compressed working fluid energy storage method comprises the following steps:

[0029] In the energy storage stage, the energy storage flow path and the shunt expansion circuit of the energy storage module are controlled to be opened, so as to compress, cool and expand the energy storage medium output from the first reservoir in sequence, thereby delivering the high-density energy storage medium to the second reservoir to achieve energy storage; at the same time, the heat storage device is controlled to be in the heat storage stage, and the electrical energy is converted into heat energy stored in the heat storage device;

[0030] In the energy release stage, the energy release flow path and the shunt compression circuit of the energy release module are controlled to be opened, so as to compress, heat up and expand the energy storage medium output from the second reservoir in sequence, thereby driving the third expander, the fourth expander and the fifth expander to generate electricity and realize energy release; at the same time, the heat storage device is controlled to be in the heat release stage to convert the thermal energy stored in the heat storage device into electrical energy.

[0031] Optionally, in the above compressed working fluid energy storage method, when in valley power, the energy storage module is controlled to operate in the energy storage stage, and the heat storage device is controlled to operate in the heat storage stage;

[0032] During peak electricity consumption, the energy release module is controlled to operate in the energy release phase, and the heat storage device is controlled to operate in the heat release phase.

[0033] The present application provides a compressed working fluid energy storage system, including a first reservoir, a second reservoir, an energy storage module, an energy release module and a heat storage device, wherein the energy storage module is used to store electrical energy, and the energy release module is used to release electrical energy. The present application converts electrical energy into heat energy and cold energy by setting a shunt expansion loop in the energy storage module, wherein the heat energy is stored and the cold energy is used to cool the energy storage working fluid, thereby avoiding dependence on an external cold source; and converts heat energy into electrical energy by setting a shunt compression loop in the energy release module, and uses the waste heat to heat the energy storage working fluid, thereby avoiding dependence on an external heat source. In this way, the layout difficulty of the compressed working fluid energy storage system is reduced, and the energy storage capacity of the system is also expanded. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of a compressed working fluid energy storage system provided in an embodiment of the present application.

[0036] exist Figure 1 middle:

[0037] 1. First reservoir; 2. Second reservoir; 3. Energy storage module; 4. Energy release module; 5. Heat storage device;

[0038] 31. first compressor; 32. second compressor; 33. first heat exchanger; 34. first heat exchange device; 35. second heat exchanger; 36. first expander; 37. second expander;

[0039] 41. third compressor; 42. fourth compressor; 43. third heat exchanger; 44. second heat exchange device; 45. fourth heat exchanger; 46. third expander; 47. fourth expander; 48. fifth expander;

[0040] 341, fifth heat exchanger; 342, sixth heat exchanger;

[0041] 441, seventh heat exchanger; 442, eighth heat exchanger;

[0042] 51. First heat storage device; 52. Second heat storage device; 53. Third heat storage device;

[0043] 511, first cold tank; 512, first hot tank; 521, second cold tank; 522, second hot tank; 531, third cold tank; 532, third hot tank. DETAILED DESCRIPTION

[0044] The present application provides a compressed working fluid energy storage system, which avoids the provision of an external cold source and an external heat source by providing a shunt expansion loop in the energy storage module and a shunt compression loop in the energy release module, thereby reducing the difficulty of arranging the compressed working fluid energy storage system. In addition, the present application also provides a compressed working fluid energy storage method applicable to the above-mentioned compressed working fluid energy storage system.

[0045] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] like Figure 1 As shown, the embodiment of the present application provides a compressed working fluid energy storage system, including a first reservoir 1, a second reservoir 2, an energy storage module 3, an energy release module 4 and a heat storage device 5, wherein the heat storage device 5 is used to recover compression heat in the energy storage stage and to release compression heat in the energy release stage. Among them, the first reservoir 1 is used to store energy storage working fluid in a gas-liquid-solid mixed state. Specifically, the first reservoir 1 assumes the function of charging and discharging a gaseous energy storage working fluid of a first pressure, that is, when storing energy, the first reservoir 1 releases a gaseous energy storage working fluid of a first pressure, and when releasing energy, the first reservoir 1 is filled with a gaseous energy storage working fluid of a first pressure; the second reservoir 2 is used to store a gaseous or liquid energy storage working fluid above a critical pressure. Specifically, the second reservoir 2 assumes the function of charging and discharging a liquid or supercritical energy storage working fluid of a second pressure, that is, when storing energy, the second reservoir 2 is filled with a liquid or supercritical energy storage working fluid of a second pressure, and when releasing energy, the second reservoir 2 releases a liquid or supercritical energy storage working fluid of a second pressure.

[0047] More specifically, the heat storage device 5 is connected between the energy storage module 3 and the energy release module 4 and has a heat storage stage and a heat release stage, so that when the energy storage stage is in the heat storage stage, the electrical energy is converted into the thermal energy of the heat storage device 5, and when the energy release stage is in the heat release stage, the thermal energy of the heat storage device 5 is converted into electrical energy, so as to realize heat recovery, avoid energy waste, and improve energy storage efficiency.

[0048] More specifically, the energy storage module 3 includes an energy storage flow path and a shunt expansion circuit. The energy storage flow path includes a first reservoir 1, a first compressor 31, a second compressor 32, a heat path of a first heat exchanger 33, a heat path of a first heat exchange device 34, a heat path of a second heat exchanger 35, a first expander 36 and a second reservoir 2 connected in series in sequence, so that the energy storage medium output from the first reservoir 1 is compressed, cooled and expanded in sequence, and a high-density energy storage medium is transported to the second reservoir 2 to realize the conversion of electrical energy into pressure energy and thermal energy storage.

[0049] The split expansion loop includes the second expander 37, the cold circuit of the second heat exchanger 35 and the first heat exchange device 34, the second compressor 32, the hot circuit of the first heat exchanger 33, the hot circuit of the first heat exchange device 34 and the second expander 37, which are connected in series in sequence. The energy storage medium in the split expansion loop merges with the energy storage medium in the energy storage flow path at the inlet of the second compressor 32, is compressed and heated by the second compressor 32, and the compression heat is recovered by the first heat exchanger 33 and the first heat exchange device 34 to realize the conversion of electric energy into thermal energy, and is expanded by the second expander 37, so that the energy storage medium is cooled to obtain cold energy and cools the energy storage medium flowing through the hot circuit of the second heat exchanger 35 through the cold circuit of the second heat exchanger 35, thereby avoiding the setting of an external cold source.

[0050] The energy release module 4 includes an energy release flow path and a bypass compression circuit. The energy release flow path includes the second reservoir 2, the third compressor 41, the cold circuit of the third heat exchanger 43, the cold circuit of the second heat exchange device 44, the cold circuit of the fourth heat exchanger 45, the third expander 46, the fourth expander 47, the first hot circuit of the third heat exchanger 43, the fifth expander 48 and the first reservoir 1 connected in series in sequence, so that the energy storage medium output from the second reservoir 2 is compressed, heated and expanded in sequence to drive the third expander 46, the fourth expander 47 and the fifth expander 48 to generate electricity to achieve energy release, and at the same time transport the energy storage medium to the first reservoir 1.

[0051] The split compression circuit includes a first heat circuit of a second heat exchange device 44, a second heat circuit of a third heat exchanger 43, a fourth compressor 42, a cold circuit of the second heat exchange device 44, a cold circuit of a fourth heat exchanger 45, a third expander 46, and a first heat circuit of the second heat exchange device 44, which are connected in series in sequence. The energy storage working fluid of the diverted compression circuit merges with the energy storage working fluid flowing through the fourth compressor 42 at the entrance of the cold circuit of the second heat exchange device 44. The merged energy storage working fluid absorbs the stored compression heat through the cold circuit of the second heat exchange device 44 and the cold circuit of the fourth heat exchanger 45, and expands through the third expander 46. The heat energy is converted into electrical energy. The energy storage working fluid is diverted in the third expander 46, and part of the energy storage working fluid releases the residual heat to the energy storage working fluid in the cold circuit of the second heat exchange device 44 and the energy storage working fluid in the cold circuit of the third heat exchanger 43 in turn through the first heat circuit of the second heat exchange device 44 and the second heat circuit of the third heat exchanger 43. In this way, the setting of an external heat source is avoided, the cost is saved, and the difficulty of arranging the compressed working fluid energy storage system is reduced.

[0052] In summary, the present application avoids the setting of an external cold source by setting a shunt expansion circuit in the energy storage module 3 to cool the energy storage medium used for energy storage; and avoids the setting of an external heat source by setting a shunt compression circuit in the energy release module 4 to heat the energy storage medium used for energy release. In this way, the difficulty of arranging the compressed medium energy storage system is reduced.

[0053] Moreover, the shunt expansion loop also has the function of converting electrical energy into thermal energy, and the shunt compression loop also has the function of converting thermal energy into electrical energy. The two together constitute the function of electric thermal energy storage, thereby adding electric thermal energy storage on the basis of compressed working fluid energy storage and expanding the energy storage capacity of the system.

[0054] Furthermore, the heat storage device 5 includes a first heat storage device 51 and a heat storage device group, and the first heat storage device 51 and the heat storage device group both store heat storage medium; wherein the first heat storage device 51 is connected to the cold circuit of the first heat exchanger 33 and the hot circuit of the fourth heat exchanger 45, and the heat storage device group is connected to the second cold circuit of the first heat exchange device 34 and the second hot circuit of the second heat exchange device 44, so that electrical energy is converted into thermal energy in the heat storage medium in the energy storage stage, and thermal energy in the heat storage medium is converted into electrical energy in the energy release stage, thereby realizing heat recovery and avoiding energy waste.

[0055] Furthermore, the heat storage device includes at least two heat storage devices; the first heat exchange device 34 and the second heat exchange device 44 each include at least two heat exchangers, and the heat exchangers of the first heat exchange device 34 and the second heat exchange device 44 are arranged one by one, and a heat storage device is connected between the two corresponding heat exchangers of the first heat exchange device 34 and the second heat exchange device 44. It should be noted that the number of heat exchangers included in the first heat exchange device 34 and the second heat exchange device 44 is set according to actual conditions. From the above, it can be seen that the heat storage device, the first heat exchange device 34 and the second heat exchange device 44 can realize the step-by-step utilization of heat and improve the efficiency of energy utilization.

[0056] Among them, the first heat exchange device 34 includes a fifth heat exchanger 341 and a sixth heat exchanger 342; the second heat exchange device 44 includes a seventh heat exchanger 441 and an eighth heat exchanger 442; the heat storage device group includes a second heat storage device 52 and a third heat storage device 53, the second heat storage device 52 is connected to the second cold circuit of the fifth heat exchanger 341 and the second hot circuit of the eighth heat exchanger 442, and the third heat storage device 53 is connected to the second cold circuit of the sixth heat exchanger 342 and the second hot circuit of the seventh heat exchanger 441. It can be seen that the first heat exchange device 34 and the heat storage device group have a simple structure, which is conducive to heat recovery.

[0057] It should be noted that the first cold circuit of the first heat exchanger 34 is equivalent to the first cold circuit of the fifth heat exchanger 341 and the sixth heat exchanger 342, and the second cold circuit of the first heat exchanger 34 is equivalent to the second cold circuit of the fifth heat exchanger 341 and the sixth heat exchanger 342; the first hot circuit of the second heat exchanger 44 is equivalent to the first hot circuit of the seventh heat exchanger 441 and the eighth heat exchanger 442, and the second hot circuit of the second heat exchanger 44 is equivalent to the second hot circuit of the seventh heat exchanger 441 and the eighth heat exchanger 442.

[0058] Furthermore, the first heat storage device 51 includes a first cold tank 511 and a first hot tank 512, and the first heat storage device 51 stores a first heat storage medium; the second heat storage device 52 includes a second cold tank 521 and a second hot tank 522, and the second heat storage device 52 stores a second heat storage medium; the third heat storage device 53 includes a third cold tank 531 and a third hot tank 532, and the third heat storage device 53 stores a third heat storage medium; wherein, in the energy storage stage, the first heat storage medium flows out of the first cold tank 511 and exchanges heat with the first heat exchanger 33 to increase the temperature before entering the first hot tank 512, and the second heat storage medium flows out of the second cold tank 521 and exchanges heat with the fifth heat exchanger 341 to increase the temperature before entering The heat storage medium flows out of the third cold tank 531 and enters the third hot tank 532 after heat exchange with the sixth heat exchanger 342 for temperature increase; in the energy release stage, the first heat storage medium flows out of the first hot tank 512 and enters the first cold tank 511 after heat exchange with the fifth heat exchanger 341 for temperature reduction; the second heat storage medium flows out of the second hot tank 522 and enters the second cold tank 521 after heat exchange with the eighth heat exchanger 442 for temperature reduction; the third heat storage medium flows out of the third hot tank 532 and enters the third cold tank 531 after heat exchange with the seventh heat exchanger 441 for temperature reduction. In this way, the step-by-step recovery and utilization of heat is achieved, heat loss is avoided, and the thermal efficiency of the system is improved.

[0059] The working temperature of the first heat storage medium>the working temperature of the second heat storage medium>the working temperature of the third heat storage medium. The heat storage medium is selected according to the temperature of the energy storage medium in the energy storage flow path, which is conducive to maximizing the recovery and utilization of heat.

[0060] Furthermore, the first heat storage medium is molten salt; the second heat storage medium and the third heat storage medium are both water. In the present application, the second heat storage medium is high-pressure water, the third heat storage medium is normal-pressure water, and the heat storage medium is water, which can reduce the heat storage cost.

[0061] In some optional embodiments, the energy storage fluid is carbon dioxide, which makes the cost of the energy storage fluid low, and realizes the resource utilization and long-term storage of carbon dioxide, with excellent comprehensive benefits.

[0062] In addition, the present application provides a compressed working fluid energy storage method, which includes the following steps: in the energy storage stage, the energy storage flow path and the shunt expansion circuit of the energy storage module 3 are controlled to be opened, so as to compress, cool and expand the energy storage working fluid output from the first reservoir 1 in sequence, thereby transporting high-density energy storage working fluid to the second reservoir 2 to achieve energy storage; at the same time, the heat storage device 5 is controlled to be in the heat storage stage to convert electrical energy into heat energy stored in the heat storage device 5.

[0063] In the energy release stage, the energy release flow path and the bypass compression circuit of the energy release module 4 are controlled to be opened, so as to compress, heat up and expand the energy storage medium output from the second reservoir 2 in sequence, thereby driving the third expander 46, the fourth expander 47 and the fifth expander 48 to generate electricity and realize energy release; at the same time, the heat storage device 5 is controlled to be in the heat release stage to convert the thermal energy stored in the heat storage device 5 into electrical energy.

[0064] Furthermore, when it is valley electricity, the energy storage module 3 is controlled to operate in the energy storage stage, and the heat storage device 5 is controlled to operate in the heat storage stage; when it is peak electricity, the energy release module 4 is controlled to operate in the energy release stage, and the heat storage device 5 is controlled to operate in the heat release stage. In this way, the valley price bonus is maximized and energy storage income is created.

[0065] For the sake of convenience, the energy storage working fluid that belongs exclusively to the energy storage flow path and the energy release flow path will be named as mainstream energy storage working fluid, the energy storage working fluid that belongs exclusively to the diversion expansion circuit and the diversion compression circuit will be named as diversion energy storage working fluid, the working fluid flowing on the overlapping flow path of the energy storage flow path and the diversion expansion circuit will be called energy storage working fluid, and the working fluid flowing on the overlapping flow path of the energy release flow path and the diversion compression circuit will be called energy storage working fluid.

[0066] Energy storage stage: The gaseous energy storage medium output from the first reservoir 1, as the mainstream energy storage medium, is compressed by the first compressor 31 and then pressurized and heated to a pressure of about 8 MPa, and then merged with the shunt energy storage medium, and then compressed by the second compressor 32 and then pressurized and heated to a temperature of more than 400°C, and then transferred heat to the first heat storage medium through the first heat exchanger 33 and stored. The temperature of the energy storage medium output from the first heat exchanger 33 is about 200°C, and then transferred heat to the shunt energy storage medium and the first heat storage medium through the fifth heat exchanger 341 and stored. The temperature of the energy storage medium output by the heat exchanger 341 is about 100°C, and then the heat is transferred to the shunt energy storage medium and the first heat storage medium through the sixth heat exchanger 342 and stored. The energy storage medium output by the sixth heat exchanger 342 enters the second heat exchanger 35 to release heat, and then expands and works through the first expander 36 and is input into the second reservoir 2. The shunt energy storage medium enters the second expander 37, and then absorbs the heat released by the energy storage medium in sections through the second heat exchanger 35, the sixth heat exchanger 342 and the fifth heat exchanger 341 in sequence, and then flows into the inlet of the second compressor 32.

[0067] Energy release stage: the second reservoir 2 outputs the energy storage working fluid as the mainstream energy storage working fluid, which is compressed and pressurized by the third compressor 41, and then heated by the third heat exchanger 43 to merge with the shunt energy storage working fluid, and then heated in stages by the seventh heat exchanger 441, the eighth heat exchanger 442 and the fourth heat exchanger 45 in sequence, and then expanded and performed work by the third expander 46. The output mainstream energy storage working fluid is then expanded and performed work by the fourth expander 47, and then released the residual heat by the third heat exchanger 43 and input into the fifth expander 48 to expand and perform work, and then input into the first reservoir 1. The shunt energy storage working fluid output by the third expander 46 is successively released in stages by the eighth heat exchanger 442, the seventh heat exchanger 441 and the third heat exchanger 43, and then pressurized by the fourth compressor 42 to merge into the inlet of the seventh heat exchanger 441 and merge with the mainstream energy storage working fluid.

[0068] It can be seen from the above technical solution that when storing energy, the energy storage flow path converts electrical energy into pressure energy and heat of the energy storage working fluid, the shunt expansion loop converts electrical energy into heat energy, and the shunt energy storage working fluid of the shunt expansion loop absorbs the waste heat of the mainstream energy storage working fluid of the energy storage flow path, so that the mainstream energy storage working fluid does not need to be configured with additional cooling conditions; when releasing energy, the energy release flow path converts the pressure energy and stored heat of the energy storage working fluid into electrical energy, the shunt compression loop converts the stored heat energy into electrical energy, and the mainstream energy storage working fluid of the energy release flow path absorbs the waste heat of the shunt energy storage working fluid of the shunt compression loop, so that the mainstream energy storage working fluid does not need to be configured with additional heating conditions; compared with the case where additional cooling or heating conditions are configured, if the cooling or heating conditions are achieved through energy consumption, the comprehensive energy efficiency of the present invention is improved, that is, the energy storage efficiency is improved; at the same time, the energy storage effect of the shunt energy storage working fluid is superimposed on the energy storage effect of the mainstream energy storage working fluid, so that the energy storage scale of the entire system is expanded, while the working fluid quality of the working fluid reservoir remains unchanged, the energy storage density of the system is improved, and it helps to reduce the unit cost of the system.

[0069] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0070] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0071] It should also be noted that in the apparatus, device and method of the present application, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0072] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0073] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth" and "sixth" used in the description of the embodiments of the present application are only used to more clearly explain the technical solutions and cannot be used to limit the scope of protection of the present application.

[0074] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A compressed working fluid energy storage system, characterized in that: include: A first reservoir (1) for releasing gaseous energy storage medium; A second reservoir (2) for storing the energy storage medium in a liquid or supercritical state; The energy storage module (3) comprises a first compressor (31), a second compressor (32), a first heat exchanger (33), a first heat exchange device (34), a second heat exchanger (35), a first expander (36), and a second expander (37); the first reservoir (1), the first compressor (31), the second compressor (32), the heat path of the first heat exchanger (33), the heat path of the first heat exchange device (34), the heat path of the second heat exchanger (35), the first expander (36), and the second reservoir (2) are sequentially connected in series to form an energy storage flow path, so that the energy storage medium output by the first reservoir (1) is compressed, cooled, and expanded in sequence, and the high-density energy storage medium is transported to the second reservoir (2), so as to realize the conversion of electrical energy into pressure energy and thermal energy and store them; The second expander (37), the cold circuit of the second heat exchanger (35), the first cold circuit of the first heat exchange device (34), the second compressor (32), the hot circuit of the first heat exchanger (33), the hot circuit of the first heat exchange device (34) and the second expander (37) are sequentially connected in series to form a split expansion circuit, so that the energy storage working medium flowing through the hot circuit of the first heat exchange device (34) is split, and part of the energy storage working medium is expanded and cooled by the second expander (37), and is heated by heat exchange with the hot circuit of the second heat exchanger (35) and the hot circuit of the first heat exchange device (34), so as to cool the energy storage working medium flowing through the hot circuit of the second heat exchanger (35) and the hot circuit of the first heat exchange device (34); The energy release module (4) comprises a third compressor (41), a fourth compressor (42), a third heat exchanger (43), a second heat exchange device (44), a fourth heat exchanger (45), a third expander (46), a fourth expander (47) and a fifth expander (48); the second reservoir (2), the third compressor (41), the cold circuit of the third heat exchanger (43), the cold circuit of the second heat exchange device (44), the cold circuit of the fourth heat exchanger (45), the third expander (46), the fourth expander (47), the first hot circuit of the third heat exchanger (43), the fifth expander (48) and the first reservoir (1) are sequentially connected in series to form an energy release flow path, so that the energy storage medium output from the second reservoir (2) is compressed, heated and expanded in sequence to drive the third expander (46), the fourth expander (47) and the fifth expander (48) to generate electricity, thereby achieving energy release, and at the same time, the energy storage medium is transported to the first reservoir (1); The first heat path of the second heat exchange device (44), the second heat path of the third heat exchanger (43) and the fourth compressor (42), the cold path of the second heat exchange device (44), the cold path of the fourth heat exchanger (45), the third expander (46) and the first heat path of the second heat exchange device (44) are sequentially connected in series to form a flow splitting compression circuit, so that the energy storage working medium is split after being expanded by the third expander (46), and part of the energy storage working medium releases residual heat to the energy storage working medium flowing through the cold path of the second heat exchange device (44) and the cold path of the third heat exchanger (43) in sequence through the first heat path of the second heat exchange device (44) and the second heat path of the third heat exchanger (43); A heat storage device (5) is connected between the energy storage module (3) and the energy release module (4) and has a heat storage stage and a heat release stage, so that when the energy storage stage is in the heat storage stage, the energy storage working fluid of the split expansion circuit merges with the energy storage working fluid of the energy release flow path at the inlet of the second compressor (32), and converts the compression heat of the second compressor (32) into thermal energy of the heat storage device (5) through the thermal path of the first heat exchanger (33) and the thermal path of the first heat exchange device (34). When the energy release stage is in the heat release stage, the energy storage working fluid exchanges heat with the second thermal path of the second heat exchange device (44) and the thermal path of the fourth heat exchanger (45) to increase the temperature, so as to convert the thermal energy stored in the heat storage device (5) into electrical energy through the third expander (46), the fourth expander (47) and the fifth expander (48).

2. The compressed working fluid energy storage system according to claim 1, characterized in that: The heat storage device (5) comprises a first heat storage device (51) and a heat storage device group, wherein the first heat storage device (51) and the heat storage device group both store heat storage medium; The first heat storage device (51) is connected to the cold circuit of the first heat exchanger (33) and the hot circuit of the fourth heat exchanger (45), and the heat storage device group is connected to the second cold circuit of the first heat exchange device (34) and the second hot circuit of the second heat exchange device (44), so that electrical energy is converted into thermal energy in the heat storage medium during the energy storage stage, and thermal energy in the heat storage medium is converted into electrical energy during the energy release stage.

3. The compressed working fluid energy storage system according to claim 2, characterized in that: The heat storage device comprises at least two heat storage devices; The first heat exchange device (34) and the second heat exchange device (44) each include at least two heat exchangers, the heat exchanger of the first heat exchange device (34) and the heat exchanger of the second heat exchange device (44) are arranged in a one-to-one correspondence, and one of the heat storage devices is connected between the two corresponding heat exchangers of the first heat exchange device (34) and the second heat exchange device (44).

4. The compressed working fluid energy storage system according to claim 3, characterized in that: The first heat exchange device (34) comprises a fifth heat exchanger (341) and a sixth heat exchanger (342); The second heat exchange device (44) comprises a seventh heat exchanger (441) and an eighth heat exchanger (442); The heat storage device group comprises a second heat storage device (52) and a third heat storage device (53), the second heat storage device (52) being connected to the second cold circuit of the fifth heat exchanger (341) and the second hot circuit of the eighth heat exchanger (442), and the third heat storage device (53) being connected to the second cold circuit of the sixth heat exchanger (342) and the second hot circuit of the seventh heat exchanger (441).

5. The compressed working fluid energy storage system according to claim 4, characterized in that: The first heat storage device (51) comprises a first cold tank (511) and a first hot tank (512), and the first heat storage device (51) stores a first heat storage medium; The second heat storage device (52) comprises a second cold tank (521) and a second hot tank (522), and the second heat storage device (52) stores a second heat storage medium; The third heat storage device (53) comprises a third cold tank (531) and a third hot tank (532), and the third heat storage device (53) stores a third heat storage medium; In the energy storage stage, the first heat storage medium flows out of the first cold tank (511) and enters the first hot tank (512) after heat exchange with the first heat exchanger (33) and temperature rises; the second heat storage medium flows out of the second cold tank (521) and enters the second hot tank (522) after heat exchange with the fifth heat exchanger (341) and temperature rises; the third heat storage medium flows out of the third cold tank (531) and enters the third hot tank (532) after heat exchange with the sixth heat exchanger (342) and temperature rises. In the energy release stage, the first heat storage medium flows out from the first hot tank (512) and enters the first cold tank (511) after heat exchange and temperature reduction with the fifth heat exchanger (341); the second heat storage medium flows out from the second hot tank (522) and enters the second cold tank (521) after heat exchange and temperature reduction with the eighth heat exchanger (442); the third heat storage medium flows out from the third hot tank (532) and enters the third cold tank (531) after heat exchange and temperature reduction with the seventh heat exchanger (441).

6. The compressed working fluid energy storage system according to claim 5, characterized in that: The operating temperature of the first heat storage medium>the operating temperature of the second heat storage medium>the operating temperature of the third heat storage medium.

7. The compressed working fluid energy storage system according to claim 6, characterized in that: The first heat storage medium is molten salt; The second heat storage medium and the third heat storage medium are both water.

8. The compressed working fluid energy storage system according to any one of claims 1 to 7, characterized in that: The energy storage medium is carbon dioxide.

9. A compressed working fluid energy storage method, characterized in that: The application is a compressed working fluid energy storage system as described in any one of claims 1 to 8, and the compressed working fluid energy storage method comprises the following steps: In the energy storage stage, the energy storage flow path and the shunt expansion circuit of the energy storage module (3) are controlled to be opened, so as to sequentially compress, cool and expand the energy storage medium output from the first reservoir (1), thereby transporting the high-density energy storage medium to the second reservoir (2) to achieve energy storage; at the same time, the heat storage device (5) is controlled to be in the heat storage stage, so as to convert electrical energy into heat energy stored in the heat storage device (5); In the energy release stage, the energy release flow path and the bypass compression circuit of the energy release module (4) are controlled to be opened, so as to compress, heat up and expand the energy storage medium output from the second reservoir (2) in sequence, thereby driving the third expander (46), the fourth expander (47) and the fifth expander (48) to generate electricity and realize energy release; at the same time, the heat storage device (5) is controlled to be in the heat release stage, so as to convert the thermal energy stored in the heat storage device (5) into electrical energy.

10. The compressed working fluid energy storage method according to claim 9, characterized in that: When the power is off-peak, the energy storage module (3) is controlled to operate in the energy storage stage, and the heat storage device (5) is controlled to operate in the heat storage stage; During peak electricity consumption, the energy release module (4) is controlled to operate in the energy release phase, and the heat storage device (5) is controlled to operate in the heat release phase.

Images