Energy storage system

Abstract

The utility model provides an energy storage system which comprises an energy storage module comprising an energy storage flow path, an energy storage working medium output by a first cavity is compressed and then shunted, one part of the energy storage working medium is compressed and expanded, the other part of the energy storage working medium is cooled and cooled again, and the energy storage working medium and the energy storage working medium converge and are sequentially cooled and subjected to latent heat exchange with a cold storage working medium in a phase change heat exchanger to be changed into a liquid state from a gas state; and the energy release module comprises an energy release flow path, an energy storage working medium output by the first liquid storage tank is subjected to latent heat exchange with the cold storage working medium in the phase change heat exchanger and is changed into a gas state from a liquid state, the energy storage working medium is divided after being heated, part of the energy storage working medium is compressed and expanded, the rest of the energy storage working medium is heated and heated again, and the energy storage working medium and the energy storage working medium converge and expand to generate power. The energy storage working medium and the cold storage working medium are subjected to latent heat exchange in the phase change heat exchanger, so that the energy storage working medium is changed into a liquid state from a gaseous state, cold energy needed in the liquefaction process of the energy storage working medium is provided by the cold storage working medium, a traditional cryogenic liquefaction method is not adopted, the liquefaction process of the energy storage working medium is simplified, and the energy storage efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of energy storage, in particular to an energy storage system. BACKGROUND

[0002] Compressed working medium energy storage is an advanced new physical energy storage technology route. The working medium that can be selected includes air, carbon dioxide, water vapor, etc. Among them, air working medium is the first choice because of its no cost and convenient availability. Compressed air energy storage has been applied for decades. Liquefied air energy storage has also entered the experimental demonstration stage. New compressed air energy storage technology is still under development.

[0003] However, the existing compressed air energy storage has high gas storage pressure (more than 10 MPa) and large volume (hundreds of thousands of cubic meters), which requires the use of underground cavern (such as salt cavern) gas storage, so that its site selection is subject to geological conditions. The existing liquefied air energy storage uses cryogenic liquefaction technology. Air needs to remove water, carbon dioxide and other impurity gases before being cooled to prevent icing. In addition, air is a mixture of nitrogen, oxygen and rare gases. The gas-liquid phase change temperature is not a fixed temperature point but a certain temperature range. Therefore, the irreversible loss of the liquefaction process is large, which makes the efficiency of the liquefied air energy storage (about 50%) much lower than that of the compressed air energy storage (about 70%). CONTENT OF THE INVENTION

[0004] Therefore, the present application provides an energy storage system. The cold energy required by the liquefaction process of the energy storage working medium is provided by the cold storage working medium. The traditional cryogenic liquefaction method is not used, the liquefaction process of the energy storage working medium is simplified, and the phase change temperature of the energy storage working medium is fixed because the energy storage working medium is a single working medium, which reduces the irreversible loss of the liquefaction process and improves the energy storage efficiency.

[0005] In order to achieve the above purpose, the present application provides the following technical solutions:

[0006] An energy storage system comprises:

[0007] A gas storage comprises a first chamber and a second chamber. The first chamber is used for storing gaseous energy storage working medium. The second chamber is used for storing gaseous cold storage working medium. The energy storage working medium is a single working medium.

[0008] A first liquid storage tank is used for storing liquid energy storage working medium.

[0009] A second liquid storage tank is used for storing liquid cold storage working medium.

[0010] The energy storage module comprises an energy storage flow path and a cooling flow path, the energy storage flow path comprises a first energy storage flow path and a second energy storage flow path, the first energy storage flow path comprises, in series, an outlet of the first chamber, a first compressor, a second compressor, a first expander, a hot path of a first heat exchanger, a hot path of a phase change heat exchanger, and an inlet of a first storage tank, and the second energy storage flow path comprises, in series, a hot path of a second heat exchanger and a hot path of a third heat exchanger, and the hot path of the second heat exchanger and the hot path of the third heat exchanger are connected in parallel with the second compressor and the first expander in series, so that the energy storage working medium output by the first chamber is divided into two parts, one part is compressed by the second compressor and expanded by the first expander in sequence, and the other part is cooled by the hot path of the second heat exchanger and the hot path of the third heat exchanger in sequence, and the two parts are combined and cooled by the hot path of the first heat exchanger in sequence, and the phase change heat exchanger exchanges latent heat with the cold storage working medium and changes from gaseous state to liquid state, and is input into the first storage tank, so as to realize the conversion of electric energy into pressure energy.

[0011] The cooling flow path comprises, in series, an outlet of the second storage tank, the phase change heat exchanger, a first cold path of the first heat exchanger, a cold path of the third heat exchanger, and an inlet of the second chamber, so that the cold storage working medium exchanges latent heat with the energy storage working medium in the phase change heat exchanger and changes from liquid state to gaseous state, is heated by the first cold path of the first heat exchanger, is heated by the cold path of the third heat exchanger, and is input into the second chamber, so that the cold storage working medium provides cold energy for liquefaction of the energy storage working medium, and the cold storage working medium cools the energy storage working medium.

[0012] The energy releasing module includes an energy releasing flow path and a heating flow path. The energy releasing flow path includes a first energy releasing flow path and a second energy releasing flow path. The first energy releasing flow path includes, in series, an outlet of the first storage tank, an expansion valve, a cold path of the phase-change heat exchanger, a cold path of a fourth heat exchanger, a third compressor, a second expander, a third expander, and an inlet of the first chamber. The second energy releasing flow path includes, in series, a cold path of a fifth heat exchanger and a cold path of a sixth heat exchanger. The fifth heat exchanger and the sixth heat exchanger are connected in parallel with the third compressor and the second expander. The energy storage working medium output by the first storage tank is sequentially subjected to latent heat exchange with the cold storage working medium in the phase-change heat exchanger to change from a liquid phase to a gas phase, is split into a part and a remainder after being subjected to heat exchange and temperature rise in the cold path of the fourth heat exchanger, the part is sequentially compressed by the third compressor and expanded by the second expander, and the remainder is sequentially subjected to heat exchange and temperature rise in the cold path of the fifth heat exchanger and the cold path of the sixth heat exchanger. The part and the remainder are combined and expanded by the third expander to generate electricity and are input into the first chamber, so as to convert pressure energy into electrical energy.

[0013] The heating flow path includes, in series, an outlet of the second chamber, a hot path of the fifth heat exchanger, a first hot path of the fourth heat exchanger, the phase-change heat exchanger, and an inlet of the second storage tank. The cold storage working medium is sequentially subjected to heat exchange and temperature drop in the hot path of the fifth heat exchanger, heat exchange and temperature drop in the first hot path of the fourth heat exchanger, and latent heat exchange with the energy storage working medium in the phase-change heat exchanger to change from a gas phase to a liquid phase, and is input into the second storage tank. The cold storage working medium releases heat energy to the energy storage working medium and heats the energy storage working medium.

[0014] Optionally, the energy storage system further includes a heat storage device group. The heat storage device group is configured to absorb heat from the energy storage flow path and release heat to the energy releasing flow path.

[0015] Optionally, the energy storage system further includes a heat storage device group. The heat storage device group is configured to absorb heat from the energy storage flow path and release heat to the energy releasing flow path.

[0016] In the energy storage stage, the first heat storage medium is output from the first cold tank and is heated by the cold path of the seventh heat exchanger, and is input into the first hot tank; in the energy release stage, the first heat storage medium is output from the first hot tank and is cooled by the hot path of the eighth heat exchanger, and is input into the first cold tank.

[0017] Optionally, in the energy storage system, the heat storage device group comprises a second heat storage device, the second heat storage device stores a second heat storage medium, and the second heat storage device comprises a ninth heat exchanger, a tenth heat exchanger, a second cold tank and a second hot tank.

[0018] The hot path of the ninth heat exchanger is connected in series between the second compressor and the first expander.

[0019] The cold path of the tenth heat exchanger is connected in series between the third compressor and the second expander.

[0020] The second cold tank is connected in series between the hot path outlet of the tenth heat exchanger and the cold path inlet of the ninth heat exchanger.

[0021] The second hot tank is connected in series between the hot path inlet of the tenth heat exchanger and the cold path outlet of the ninth heat exchanger.

[0022] In the energy storage stage, the second heat storage medium is output from the second cold tank and is heated by the cold path of the ninth heat exchanger, and is input into the second hot tank; in the energy release stage, the second heat storage medium is output from the second hot tank and is cooled by the hot path of the tenth heat exchanger, and is input into the second cold tank.

[0023] Optionally, in the energy storage system, the energy storage system further comprises a cold storage tank group, the cold storage tank group stores a cold storage medium, the cold storage tank group comprises a first cold storage tank and a second cold storage tank, the first cold storage tank is connected in series between the second cold path inlet of the first heat exchanger and the second hot path outlet of the fourth heat exchanger, and the second cold storage tank is connected in series between the second cold path outlet of the first heat exchanger and the second hot path inlet of the fourth heat exchanger.

[0024] In the energy storage stage, the cold storage medium is output from the first cold storage tank and is heated by the second cold path of the first heat exchanger, and is input into the second cold storage tank; in the energy release stage, the cold storage medium is output from the second cold storage tank and is cooled by the second hot path of the fourth heat exchanger, and is input into the second cold tank.

[0025] Optionally, the energy storage system further comprises a third heat storage tank group, which stores a third heat storage medium, and the third heat storage tank group comprises a third cold tank and a third hot tank, the third cold tank is connected in series between the cold inlet of the second heat exchanger and the hot outlet of the sixth heat exchanger, and the third hot tank is connected in series between the cold outlet of the second heat exchanger and the hot inlet of the sixth heat exchanger.

[0026] In the energy storage stage, the third heat storage medium is output from the third cold tank, is heated by the cold path of the second heat exchanger, is input into the third hot tank; in the energy release stage, the third heat storage medium is output from the third hot tank, is cooled by the hot path of the sixth heat exchanger, and is input into the third cold tank.

[0027] Optionally, in the energy storage system, the gas storage is in a flexible airbag structure, and the first chamber and the second chamber in the flexible airbag structure can be deformed flexibly.

[0028] Optionally, in the energy storage system, the energy storage working medium is nitrogen, and the cold storage working medium is methane.

[0029] Optionally, in the energy storage system, the first heat storage medium is heat-conducting oil, molten salt or high-pressure water.

[0030] The second heat storage medium is heat-conducting oil, molten salt or high-pressure water.

[0031] Optionally, in the energy storage system, the cold storage medium is liquid propane.

[0032] The energy storage system provided in the application comprises a first chamber, a second chamber, a first energy storage flow path, a second energy storage flow path, a first energy storage tank, a second energy storage tank, a cooling flow path, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a fifth heat exchanger and a sixth heat exchanger.

[0033] In the energy releasing stage, the energy storage working substance is output from the first storage tank and sequentially expanded and depressurized by the expansion valve, phase-changed from liquid to gas by latent heat exchange with the energy storage working substance in the phase-change heat exchanger, split, and partially input into the first energy releasing flow path and the rest input into the second energy releasing flow path; the part input into the first energy releasing flow path is sequentially compressed and expanded, the rest input into the second energy releasing flow path is sequentially first heated and second heated, and then the part and the rest are combined and expanded by the expander to generate electricity and input into the first chamber; the cold storage working substance of the cooling flow path is output from the second chamber and sequentially first cooled and second cooled, phase-changed from gas to liquid by latent heat exchange with the energy storage working substance in the phase-change heat exchanger, and input into the second storage tank.

[0034] As can be seen from the above, in the energy storage stage, the energy storage working substance and the cold storage working substance exchange latent heat in the phase-change heat exchanger to make the energy storage working substance phase-change from gas to liquid, and the cold energy required by the energy storage working substance in the liquefaction process is provided by the cold storage working substance, and the traditional cryogenic liquefaction method is not used, the liquefaction process of the energy storage working substance is simplified, and because the energy storage working substance is single, the phase-change temperature of the energy storage working substance is fixed, the irreversible loss of the liquefaction process is reduced, and the energy storage efficiency is improved; in the energy releasing stage, the energy storage working substance and the cold storage working substance exchange latent heat in the phase-change heat exchanger to make the energy storage working substance phase-change from gas to liquid, and the heat energy recovered by the cold storage working substance in the energy storage stage is released to the energy storage working substance in the energy releasing stage, and the energy storage working substance is gasified, so that the energy is fully utilized. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of the provided drawings.

[0036] Figure 1 A flow chart of an energy storage system according to an embodiment of the present application.

[0037] In Figure 1 which:

[0038] 1, gas storage; 101, first chamber; 102, second chamber;

[0039] 2, first storage tank; 3, second storage tank; 4, energy storage flow path; 5, cooling flow path; 6, first energy storage flow path; 7, second energy storage flow path; 8, first compressor; 9, second compressor; 10, first expander; 11, first heat exchanger; 12, phase change heat exchanger; 13, second heat exchanger; 14, third heat exchanger; 15, energy release flow path; 16, heating flow path; 17, first energy release flow path; 18, second energy release flow path; 19, expansion valve; 20, fourth heat exchanger; 21, third compressor; 22, second expander; 23, third expander; 24, fifth heat exchanger; 25, sixth heat exchanger; 26, first heat storage device; 27, seventh heat exchanger; 28, eighth heat exchanger; 261, first cold tank; 262, first hot tank; 29, second heat storage device; 30, ninth heat exchanger; 31, tenth heat exchanger; 291, second cold tank; 292, second hot tank; 32, cold storage tank group; 321, first cold storage tank; 322, second cold storage tank; 33, heat storage tank group; 331, third cold tank; 332, third hot tank. DETAILED DESCRIPTION

[0040] The application provides an energy storage system, cold energy required by an energy storage working medium liquefaction process is provided by a cold storage working medium, a traditional cryogenic liquefaction method is not used, the energy storage working medium liquefaction process is simplified, and because the energy storage working medium is a single working medium, the phase change temperature of the energy storage working medium is fixed, the irreversible loss of the liquefaction process is reduced, and the energy storage efficiency is improved.

[0041] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the application.

[0042] As Figure 1As shown, the embodiment of the present application provides a kind of energy storage system, in energy storage phase, energy storage working medium is exported from first chamber 101 to energy storage flow path 4, and at the same time, cold storage working medium is exported from second liquid tank 3 to cooling flow path 5 and enters second chamber 102.Specifically, in energy storage flow path 4, energy storage working medium is branched after being compressed by first compressor 8, one part enters first energy storage flow path 6, another part enters second energy storage flow path 7;Energy storage working medium entering first energy storage flow path 6 is successively compressed by second compressor 9, expanded by first expander 10, another part is successively heat-exchanged with cold storage working medium by the heat path of second heat exchanger 13 and is heat-exchanged with cold storage working medium again by the heat path of third heat exchanger 14, and then one part and another part are merged and successively heat-exchanged with cold storage working medium by the heat path of first heat exchanger 11, heat-exchanged with cold storage working medium by the heat path of phase change heat exchanger 12 to exchange latent heat and change from gaseous state to liquid state, and are input into first liquid tank 2;Cold storage working medium of cooling flow path 5 is exported from second liquid tank 3 and successively exchanges latent heat with energy storage working medium by phase change heat exchanger 12 to change from liquid state to gaseous state, exchanges heat with energy storage working medium by the first cold path of first heat exchanger 11, exchanges heat with cold storage working medium again by the cold path of third heat exchanger 14 and is input into second chamber 102.

[0043] In energy release phase, energy storage working medium is exported from second liquid tank 3 to energy release flow path 15, and at the same time, cold storage working medium is exported from second chamber 102 to heating flow path 16.Specifically, energy storage working medium is exported from second liquid tank 3 and successively expanded by expansion valve 19, exchanges latent heat with energy storage working medium by phase change heat exchanger 12 to change from liquid state to gaseous state and is heat-exchanged with energy storage working medium by the heat path of first heat exchanger 11, exchanges heat with cold storage working medium by the heat path of second heat exchanger 12 to change from gaseous state to liquid state, and is input into first chamber 101;Cold storage working medium is exported from second chamber 102 and successively exchanges heat with energy storage working medium by the heat path of first heat exchanger 11, exchanges heat with energy storage working medium by the heat path of second heat exchanger 12 to change from gaseous state to liquid state, and is input into first chamber 101.

[0044] In summary, in the energy storage stage, the latent heat exchange between the energy storage working medium and the cold storage working medium in the phase change heat exchanger 12 causes the energy storage working medium to change from a gaseous phase to a liquid phase, and it can be seen that the cold energy required by the energy storage working medium liquefaction process is provided by the cold storage working medium. The traditional cryogenic liquefaction method is not used, the energy storage working medium liquefaction process is simplified, and because the energy storage working medium is a single working medium, the phase change temperature of the energy storage working medium is fixed, the irreversible loss of the liquefaction process is reduced, and the energy storage efficiency is improved. In the energy release stage, the latent heat exchange between the energy storage working medium and the cold storage working medium in the phase change heat exchanger 12 causes the energy storage working medium to change from a gaseous phase to a liquid phase, and it can be seen that the heat energy recovered by the cold storage working medium in the energy storage stage is released to the energy storage working medium in the energy release stage, and the energy storage working medium is gasified, so as to realize the full utilization of energy.

[0045] In addition, the phase state transition of the energy storage working medium and the cold storage working medium is realized by latent heat exchange between the energy storage working medium and the cold storage working medium. In this way, the setting of an external cold source when the energy storage working medium is liquefied and the setting of an external heat source when the energy storage working medium is gasified are avoided. In addition, the cold storage working medium is also used to cool the energy storage working medium in the energy storage stage and heat the energy storage working medium in the energy release stage, so as to fully utilize the energy inside the energy storage system.

[0046] In an optional embodiment, the energy storage system further comprises a heat storage device group, which is used to absorb the heat of the energy storage flow path 4 and release the heat to the energy release flow path 15. It can be understood that the heat storage device group absorbs the heat of the energy storage working medium and stores the heat in the energy storage stage; and releases the previously stored heat to the energy storage working medium in the energy release stage. In this way, the heat of the energy storage system is fully utilized, and the energy storage efficiency is improved.

[0047] The heat storage device group comprises a first heat storage device 26, the first heat storage device 26 stores a first heat storage medium, and the first heat storage device 26 comprises a seventh heat exchanger 27, an eighth heat exchanger 28, a first cold tank 261 and a first hot tank 262. The hot path of the seventh heat exchanger 27 is connected in series between the first compressor 8 and the inlet of the second energy storage flow path 7. The cold path of the eighth heat exchanger 28 is connected in series between the third expander 23 and the outlet of the second energy release flow path 18. The first cold tank 261 is connected in series between the cold path inlet of the seventh heat exchanger 27 and the hot path outlet of the eighth heat exchanger 28. The first hot tank 262 is connected in series between the cold path outlet of the seventh heat exchanger 27 and the hot path inlet of the eighth heat exchanger 28. In the energy storage stage, the first heat storage medium is output from the first cold tank 261 and is heat-exchanged and heated by the cold path of the seventh heat exchanger 27, and is input into the first hot tank 262. In the energy release stage, the first heat storage medium is output from the first hot tank 262 and is heat-exchanged and cooled by the hot path of the eighth heat exchanger 28, and is input into the first cold tank 261.

[0048] The heat storage device group comprises a second heat storage device 29, the second heat storage device 29 stores a second heat storage medium, the second heat storage device 29 comprises a ninth heat exchanger 30, a tenth heat exchanger 31, a second cold tank 291 and a second hot tank 292; the hot path of the ninth heat exchanger 30 is connected in series between the second compressor 9 and the first expander 10; the cold path of the tenth heat exchanger 31 is connected in series between the third compressor 21 and the second expander 22; the second cold tank 291 is connected between the hot path outlet of the tenth heat exchanger 31 and the cold path inlet of the ninth heat exchanger 30; the second hot tank 292 is connected between the hot path inlet of the tenth heat exchanger 31 and the cold path outlet of the ninth heat exchanger 30; wherein, in the energy storage stage, the second heat storage medium is output from the second cold tank 291 and is heated by the cold path of the ninth heat exchanger 30, and is input into the second hot tank 292; in the energy release stage, the second heat storage medium is output from the second hot tank 292 and is cooled by the hot path of the tenth heat exchanger 31, and is input into the second cold tank 291.

[0049] As can be seen from the above, the heat storage device (the first heat storage device 26 and the second heat storage device 29) can store heat energy during valley electricity and release heat energy during peak electricity or when needed, thereby reducing energy waste and improving the overall heat energy utilization rate of the system. In addition, the heat storage device has a simple structure and a simple and reliable operation principle.

[0050] In some other optional embodiments, the heat storage device group can only comprise one cold tank, multiple hot tanks and multiple heat exchangers, and the number of heat exchangers is twice the number of hot tanks. In this way, in the energy storage stage, the heat storage medium can be output from the cold tank and sequentially flow through different heat exchangers to absorb heat and then enter the corresponding hot tank for heat storage. In the energy release stage, the heat storage medium can be output from different hot tanks to release heat to another heat exchanger connected thereto and then be input into the cold tank. Of course, the arrangement and connection mode of the cold tank, the hot tank and the heat exchanger are not limited to this, and the specific arrangement mode meets the requirements of absorbing heat energy in the energy storage stage and releasing heat energy in the energy release stage, which are within the protection scope of the present application.

[0051] In an optional embodiment, the energy storage system further comprises a cold storage tank group 32, the cold storage tank group 32 storing a cold storage medium, the cold storage tank group 32 comprising a first cold storage tank 321 and a second cold storage tank 322, the first cold storage tank 321 being connected in series between the second cold inlet of the first heat exchanger 11 and the second hot outlet of the fourth heat exchanger 20, and the second cold storage tank 322 being connected in series between the second cold outlet of the first heat exchanger 11 and the second hot inlet of the fourth heat exchanger 20; wherein, in the energy storage stage, the cold storage medium is output from the first cold storage tank 321, is heated by the second cold path of the first heat exchanger 11, and is input into the second cold storage tank 322; and in the energy release stage, the cold storage medium is output from the second cold storage tank 322, is cooled by the second hot path of the fourth heat exchanger 20, and is input into the second cold tank 291. The cold storage tank group 32 is provided to make the time and mode of energy storage and release more flexible, and to achieve full utilization of energy in the energy storage system.

[0052] In an optional embodiment, the energy storage system further comprises a cold storage tank group 32, the cold storage tank group 32 storing a cold storage medium, the cold storage tank group 32 comprising a first cold storage tank 321 and a second cold storage tank 322, the first cold storage tank 321 being connected in series between the second cold inlet of the first heat exchanger 11 and the second hot outlet of the fourth heat exchanger 20, and the second cold storage tank 322 being connected in series between the second cold outlet of the first heat exchanger 11 and the second hot inlet of the fourth heat exchanger 20; wherein, in the energy storage stage, the cold storage medium is output from the first cold storage tank 321, is heated by the second cold path of the first heat exchanger 11, and is input into the second cold storage tank 322; and in the energy release stage, the cold storage medium is output from the second cold storage tank 322, is cooled by the second hot path of the fourth heat exchanger 20, and is input into the second cold tank 291. The cold storage tank group 32 is provided to make the time and mode of energy storage and release more flexible, and to achieve full utilization of energy in the energy storage system.

[0053] In an optional embodiment, the gas storage 1 is provided in a flexible air bag structure, and the flexible air bag structure comprises a first cavity 101 and a second cavity 102 which can be deformed. As known from the above, in the energy storage stage, the energy storage medium is output from the first cavity 101, and the cold storage medium is input into the second cavity 102; and in the energy release stage, the energy storage medium is input into the first cavity 101, and the cold storage medium is output from the second cavity 102. It can be seen that the two mediums are input and output alternately, so that the space of the gas storage 1 is always effectively utilized, without the need to increase the investment and land area of the gas storage 1.

[0054] In other optional embodiments, the gas storage 1 can be provided in a rigid structure, and the rigid structure is divided into two cavities by a flexible and deformable air bag structure.

[0055] In an optional embodiment, the energy storage working substance is nitrogen, and the cold storage working substance is methane. The latent heat exchange between methane and nitrogen is an efficient energy utilization mode, and can realize effective conversion and utilization of energy in the phase change process of matter.

[0056] In an optional embodiment, the first heat storage medium is heat conducting oil, fused salt or high-pressure water; and the second heat storage medium is heat conducting oil, fused salt or high-pressure water. It should be noted that the first heat storage medium and the second heat storage medium can be the same or different. For the convenience of explanation, the first heat storage medium and the second heat storage medium are collectively referred to as heat storage medium. The heat conducting oil is used as the heat storage medium, and the system realizes zero emission and safety and environmental protection in the fuel-free circulating process. The fused salt has a wider working temperature range, and the fused salt heat storage has the characteristics of large scale, long time, safety and stability, and no site selection limitation. The high-pressure water has the characteristics of no pollution and high operation efficiency. In actual engineering, the specific medium used as the heat storage medium is selected according to the requirements.

[0057] It should be noted that the third heat storage medium can also be heat conducting oil, fused salt or high-pressure water.

[0058] In an optional embodiment, the cold storage medium is liquid propane. Preferably, the cold storage medium is low-temperature liquid propane, because the low-temperature liquid propane has strong cold storage capacity, and it has obvious advantages in energy efficiency, safety, environmental friendliness, economy and system response speed.

[0059] In an example, in the energy storage stage, nitrogen is output from the first chamber 101, compressed to about 1.8 MPa / 450℃ by the first compressor 8, and then absorbs the compression heat of the high-temperature section by the seventh heat exchanger 27, and is then divided into two streams: one is further compressed to about 6 MPa / 450℃ by the second compressor 9, and then absorbs the compression heat by the ninth heat exchanger 30, and the other absorbs the compression heat of the low-temperature section by the second heat exchanger 13; the nitrogen output by the ninth heat exchanger 30 is expanded to do work and is reduced in pressure and temperature to about 1.8 MPa / -50℃ by the first expander 10, and the nitrogen output by the second heat exchanger 13 is cooled to about -50℃ by the propane in the third heat exchanger 14, and then the two streams of nitrogen are combined and input into the first heat exchanger 11 to be cooled to about -160℃ by the propane and the cold storage medium; the nitrogen is then input into the phase change heat exchanger 12 to exchange heat with the normal-pressure low-temperature liquid methane, the nitrogen is liquefied, and the methane is gasified, the liquid nitrogen is input into the first liquid storage tank 2, the methane gas is input into the first heat exchanger 11, and then is input into the second chamber 102 after passing through the third heat exchanger 14.

[0060] The energy releasing stage: liquid nitrogen is output from the first liquid storage tank 2, is regulated to about 1.5 MPa through the expansion valve 19, exchanges heat with the low-pressure gaseous methane at normal pressure through the phase change heat exchanger 12, the liquid nitrogen is gasified and the methane is liquefied, the liquid methane returns to the second liquid storage tank 3, the nitrogen gas at-160 DEG C is input into the fourth heat exchanger 20 and is heated to about-50 DEG C by the propane and methane gas, is divided into two streams: one stream exchanges heat with the methane gas from the second chamber 102 through the fifth heat exchanger 24 to cool the methane gas to about-50 DEG C, the other stream is compressed to about 6 MPa through the third compressor 21; the energy storage working medium output from the fifth heat exchanger 24 absorbs heat through the sixth heat exchanger 25 again, the energy storage working medium output from the third compressor 21 absorbs heat through the tenth heat exchanger 31 again to be heated to about 420 DEG C, is expanded through the second expander 22 to generate electricity, the pressure is reduced to about 1.5 MPa, is combined with the energy storage working medium output from the sixth heat exchanger 25 and is input into the eighth heat exchanger 28 to absorb heat and be heated to about 420 DEG C, is expanded through the third expander 23 to generate electricity, the pressure is reduced to normal pressure and returns to the first chamber 101.

[0061] According to the above operation mode, for a hundred megawatt energy storage system: the energy storage is 6 hours, the total flow of nitrogen is about 160 kg / s, the flow of methane is about 41 kg / s, the energy storage power is about 97 MW; the energy releasing is 4 hours, the total flow of nitrogen is about 240 kg / s, the flow of methane is about 61 kg / s, the power of electricity generation is about 100 MW; the system energy storage round-trip efficiency is about 69%; it can be seen that the efficiency of the energy storage system of the present application is much higher than that of the conventional liquefied air energy storage and reaches the level of compressed air energy storage.

[0062] From the above technical solution, the present application has the following beneficial effects:

[0063] The gaseous energy storage working medium and the cold storage working medium are stored in the ground gas film warehouse at normal pressure and normal temperature, and the liquid energy storage working medium and the cold storage working medium are stored in the conventional ground container, without the need of special geographical resource conditions such as underground salt cave gas storage; the energy storage working medium and the cold storage working medium are natural working medium in single element form, with excellent physical properties, and the state change is realized through the mutual and reverse gas-liquid phase change, the irreversible loss of heat exchange process is small, and the heat exchange efficiency is high;

[0064] The sensible heat type cold energy of the energy storage working medium is recovered by the low-temperature liquid cold storage medium and is used for pre-cooling of the energy storage working medium, avoiding the waste of cold energy; the sensible heat type cold energy of the cold storage working medium is recovered by the split flow of the energy storage working medium and is used for pre-cooling of the energy storage working medium, further avoiding the waste of cold energy; the additional electric energy is converted into high-temperature heat energy through the re-compression of the split flow of the energy storage working medium, and the energy storage working medium recovers the pressure energy through expansion and is cooled, so that the cold energy of the energy storage working medium, the cold storage working medium and the cold storage medium is balanced, the energy storage capacity and the energy storage efficiency are improved.

[0065] The above describes the basic principles of the present application in combination with specific embodiments, but it should be noted that the advantages, benefits, effects and the like mentioned in the present application are only examples and are not limiting, and these advantages, benefits, effects and the like cannot be considered as necessary for each embodiment of the present application. In addition, the above specific details disclosed are only for the purpose of illustration and understanding, and are not limiting, and the above details do not limit the present application to be necessarily implemented with the above specific details.

[0066] The block diagrams of the devices, apparatuses, equipment, systems involved in the present application are only illustrative examples and are not intended to require or imply the connection, arrangement, configuration as shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, equipment, systems can be connected, arranged, configured in any manner. Words such as "include", "contain", "have" and the like are open-ended words, meaning "including but not limited to", and can be used interchangeably. The words "or" and "and" used herein mean the word "and / or", and can be used interchangeably unless the context clearly indicates otherwise. The word "such as" used herein means the phrase "such as but not limited to", and can be used interchangeably.

[0067] It should also be noted that in the devices, equipment and methods of the present application, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be considered as equivalent solutions of the present application.

[0068] The above description of the disclosed aspects is provided so that any person skilled in the art can make or use the present application. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can 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 is intended to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0069] It should be understood that the adjectives "first", "second", "third", "fourth", "fifth" and "sixth" used in the embodiments of the present application are only used for clearer description of the technical solutions, and cannot be used to limit the protection scope of the present application.

[0070] The above description has been given for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of 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. An energy storage system, characterized in that, include: The gas storage tank (1) includes a first chamber (101) and a second chamber (102). The first chamber (101) is used to store a gaseous energy storage medium, and the second chamber (102) is used to store a gaseous cold storage medium. The energy storage medium is a single medium. The first liquid storage tank (2) is used to store the liquid energy storage working fluid; The second liquid storage tank (3) is used to store the liquid cold storage working fluid; The energy storage module includes an energy storage flow path (4) and a cooling flow path (5). The energy storage flow path (4) includes a first energy storage flow path (6) and a second energy storage flow path (7). The first energy storage flow path (6) includes the outlet of the first chamber (101), the heat path of the first compressor (8), the heat path of the second compressor (9), the first expander (10), the heat path of the first heat exchanger (11), the heat path of the phase change heat exchanger (12), and the inlet of the first liquid storage tank (2), which are connected in series. The second energy storage flow path (7) includes the heat path of the second heat exchanger (13) and the heat path of the third heat exchanger (14), which are connected in series. The heat path of the second heat exchanger (13) and the heat path of the third heat exchanger (14) are connected in series with the heat path of the second compressor (9), the first heat exchanger (10), the first heat exchanger (11), the phase change heat exchanger (12), and the inlet of the first liquid storage tank (2). The first expander (10) is connected in parallel so that the energy storage medium output from the first chamber (101) is compressed by the first compressor (8) and then split. One part is compressed by the second compressor (9) and expanded by the first expander (10). The other part is cooled by heat exchange through the hot path of the second heat exchanger (13) and the hot path of the third heat exchanger (14). The first part and the other part are combined and cooled by heat exchange through the hot path of the first heat exchanger (11). The cold storage medium undergoes latent heat exchange with the phase change heat exchanger (12) to change from gaseous to liquid state and is input into the first liquid storage tank (2) to realize the conversion of electrical energy into pressure energy. The cooling flow path (5) includes the outlet of the second liquid storage tank (3), the phase change heat exchanger (12), the first cold path of the first heat exchanger (11), the cold path of the third heat exchanger (14), and the inlet of the second chamber (102) connected in series. This allows the cold storage medium to exchange latent heat with the energy storage medium in the phase change heat exchanger (12) to change from liquid to gas, undergo heat exchange and temperature rise through the first cold path of the first heat exchanger (11), undergo heat exchange and temperature rise through the cold path of the third heat exchanger (14), and be input into the second chamber (102). This allows the cold storage medium to provide cold energy for the liquefaction of the energy storage medium and the cold storage medium to cool the energy storage medium. The energy release module includes an energy release flow path (15) and a heating flow path (16). The energy release flow path (15) includes a first energy release flow path (17) and a second energy release flow path (18). The first energy release flow path (17) includes the outlet of the first liquid storage tank (2), an expansion valve (19), a cold path of the phase change heat exchanger (12), a cold path of the fourth heat exchanger (20), a third compressor (21), a second expander (22), a third expander (23), and the inlet of the first chamber (101), which are connected in series. The second energy release flow path (18) includes the cold path of the fifth heat exchanger (24) and the cold path of the sixth heat exchanger (25), which are connected in series. The fifth heat exchanger (24) and the sixth heat exchanger (25), which are connected in series, are connected to the third compressor (21), the second expander (22), the third expander (23), and the inlet of the first chamber (101). The compressor (21) and the second expander (22) are connected in parallel so that the energy storage medium output from the first liquid storage tank (2) undergoes latent heat exchange with the cold storage medium in the phase change heat exchanger (12) to change from liquid to gas. After heat exchange and temperature rise through the cold path of the fourth heat exchanger (20), the medium is split. Part of the medium is compressed by the third compressor (21) and expanded by the second expander (22). The remaining part is heated by heat exchange through the cold path of the fifth heat exchanger (24) and the cold path of the sixth heat exchanger (25). The part and the remaining part are combined and expanded by the third expander (23) to generate electricity, which is then input into the first chamber (101) to realize the conversion of pressure energy into electrical energy. The heating flow path (16) includes the outlet of the second chamber (102), the hot path of the fifth heat exchanger (24), the first hot path of the fourth heat exchanger (20), the inlet of the phase change heat exchanger (12) and the second liquid storage tank (3) connected in series, so that the cold storage medium is cooled by heat exchange through the hot path of the fifth heat exchanger (24), cooled by heat exchange through the first hot path of the fourth heat exchanger (20), and undergoes latent heat exchange with the energy storage medium in the phase change heat exchanger (12) to change from gaseous to liquid state, and is input into the second liquid storage tank (3), so that the cold storage medium releases heat energy by vaporizing the energy storage medium, and the cold storage medium heats the energy storage medium.

2. The energy storage system according to claim 1, characterized in that, It also includes a heat storage device group, which is used to absorb the heat of the energy storage flow path (4) and release the heat to the energy release flow path (15).

3. The energy storage system according to claim 2, characterized in that, The heat storage device group includes a first heat storage device (26), which stores a first heat storage medium. The first heat storage device (26) includes a seventh heat exchanger (27), an eighth heat exchanger (28), a first cold tank (261), and a first hot tank (262). The heat path of the seventh heat exchanger (27) is connected in series between the inlet of the first compressor (8) and the inlet of the second energy storage flow path (7); The cold path of the eighth heat exchanger (28) is connected in series between the outlet of the third expander (23) and the outlet of the second energy release path (18); The first cold tank (261) is connected in series between the cold inlet of the seventh heat exchanger (27) and the hot outlet of the eighth heat exchanger (28); The first hot tank (262) is connected in series between the cold outlet of the seventh heat exchanger (27) and the hot inlet of the eighth heat exchanger (28); In the energy storage stage, the first heat storage medium is output from the first cold tank (261) and heated by heat exchange through the cold path of the seventh heat exchanger (27) before being input into the first hot tank (262); in the energy release stage, the first heat storage medium is output from the first hot tank (262) and cooled by heat exchange through the hot path of the eighth heat exchanger (28) before being input into the first cold tank (261).

4. The energy storage system according to claim 3, characterized in that, The heat storage device group includes a second heat storage device (29), which stores a second heat storage medium. The second heat storage device (29) includes a ninth heat exchanger (30), a tenth heat exchanger (31), a second cold tank (291), and a second hot tank (292). The heat path of the ninth heat exchanger (30) is connected in series between the second compressor (9) and the first expander (10); The cooling circuit of the tenth heat exchanger (31) is connected in series between the third compressor (21) and the second expander (22); The second cold tank (291) is connected in series between the hot outlet of the tenth heat exchanger (31) and the cold inlet of the ninth heat exchanger (30); The second hot tank (292) is connected in series between the hot inlet of the tenth heat exchanger (31) and the cold outlet of the ninth heat exchanger (30); During the energy storage phase, the second heat storage medium is output from the second cold tank (291) and heated by heat exchange through the cold path of the ninth heat exchanger (30) before being input into the second hot tank (292); during the energy release phase, the second heat storage medium is output from the second hot tank (292) and cooled by heat exchange through the hot path of the tenth heat exchanger (31) before being input into the second cold tank (291).

5. The energy storage system according to claim 4, characterized in that, It also includes a cold storage tank group (32), which stores a cold storage medium. The cold storage tank group (32) includes a first cold storage tank (321) and a second cold storage tank (322). The first cold storage tank (321) is connected in series between the second cold path inlet of the first heat exchanger (11) and the second hot path outlet of the fourth heat exchanger (20). The second cold storage tank (322) is connected in series between the second cold path outlet of the first heat exchanger (11) and the second hot path inlet of the fourth heat exchanger (20). In the energy storage stage, the cold storage medium is output from the first cold storage tank (321) and heated by heat exchange through the second cold path of the first heat exchanger (11) before being input into the second cold storage tank (322); in the energy release stage, the cold storage medium is output from the second cold storage tank (322) and cooled by heat exchange through the second hot path of the fourth heat exchanger (20) before being input into the second cold tank (291).

6. The energy storage system according to claim 1, characterized in that, It also includes a heat storage tank group (33), which stores a third heat storage medium. The heat storage tank group (33) includes a third cold tank (331) and a third hot tank (332). The third cold tank (331) is connected in series between the cold inlet of the second heat exchanger (13) and the hot outlet of the sixth heat exchanger (25). The third hot tank (332) is connected in series between the cold outlet of the second heat exchanger (13) and the hot inlet of the sixth heat exchanger (25). In the energy storage stage, the third heat storage medium is output from the third cold tank (331) and heated by heat exchange through the cold path of the second heat exchanger (13) before being input into the third hot tank (332); in the energy release stage, the third heat storage medium is output from the third hot tank (332) and cooled by heat exchange through the hot path of the sixth heat exchanger (25) before being input into the third cold tank (331).

7. The energy storage system according to claim 1, characterized in that, The gas storage tank (1) is configured as a flexible airbag structure, the flexible airbag structure includes a first chamber (101) that can be flexibly deformed and a second chamber (102) that can be flexibly deformed.

8. The energy storage system according to any one of claims 1-7, characterized in that, The energy storage medium is nitrogen, and the cold storage medium is methane.

9. The energy storage system according to claim 4, characterized in that, The first heat storage medium is heat transfer oil, molten salt, or high-pressure water; The second heat storage medium is heat transfer oil, molten salt, or high-pressure water.

10. The energy storage system according to claim 5, characterized in that, The cold storage medium is liquid propane.

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