A device system and method for storing energy and heat of liquid compressed air

Abstract

The present invention provides a device system and method for storing energy and heat in liquid compressed air. The heat storage and heat release processes in the device system both use secondary circuits, and polyethylene glycol is used as the intermediate heat medium in the low temperature section, molten salt is used as the intermediate heat medium in the high temperature section, and heat transfer oil is used as the heat storage medium, which solves the problem of leakage of heat transfer oil from high temperature air, and greatly improves the safety of the system; and polyethylene glycol and molten salt are used as intermediate heat media, which only circulate in a closed loop, and no additional storage device is required, which will not significantly increase investment. The device system in the present invention also realizes the storage and recycling of heat and cold, and is suitable for large-scale industrial applications.

Description

Technical Field

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

[0002] In recent years, my country's installed capacity of renewable energy power generation has increased year by year, but the inherent characteristics of renewable energy such as instability and volatility have seriously restricted its grid-connected use. Energy storage technology has significant peak-shaving and frequency-regulating capabilities, and can achieve non-steady-state storage and stable output of photovoltaic and wind power generation, providing an effective way to solve the problem of renewable energy utilization. Therefore, it is urgent to develop various safe, reliable, continuous and efficient large-scale energy storage technologies.

[0003] Compressed air energy storage technology, as an energy storage technology that meets the needs of large-scale peak load regulation, has the advantages of large energy storage capacity, long life, high energy conversion efficiency, and low environmental pollution, and has received widespread attention. Among them, liquid compressed air energy storage technology compresses and liquefies air for energy storage. When releasing energy, the liquefied air is pressurized and gasified, and then enters the turbine to expand and drive the generator to generate electricity, while recovering compression waste heat, expansion waste cold, and vaporization latent heat. This technology uses liquid air to achieve energy storage, which greatly reduces the energy storage pressure and storage tank volume. It has the advantages of high energy storage density, safety and efficiency, and is not restricted by geographical conditions. The liquid compressed air energy storage system will generate a lot of heat during the energy storage process. Only by storing this heat and using it when releasing energy can it have a high electrical-electrical efficiency.

[0004] CN112780409A discloses a system and method for coupling a gas engine and liquid compressed air energy storage using continuous detonation, including a liquid compressed air energy storage system and a gas-steam combined cycle system; through multiple couplings between the liquid compressed air energy storage system and the gas-steam combined cycle, the air compressor is driven by an electric motor powered by the power grid, the heat of the energy storage compression process is stored by a thermal oil storage tank, the heat absorbed during the energy release expansion process is provided by high-temperature thermal oil, and the released supercritical compressed air is used as fuel air, dilution air, and air intake of the gas turbine. The decoupling of the compressor and the turbine is achieved, the cascade utilization of the high-temperature exhaust heat of the gas turbine is improved, the operating efficiency of the energy storage peak-shaving system is improved, and the overall peak-shaving capacity of the system is increased.

[0005] CN113565590A discloses a wide-load deep peak-shaving power generation system coupled with compressed air energy storage and coal-fired units, including a coal-fired power generation subsystem and a compressed air energy storage subsystem connected to the coal-fired power generation subsystem; the compressed air energy storage subsystem includes a steam turbine unit 3, an air compressor system, an intercooling system connected to the air compression system, an energy storage system connected to the intercooling system, a heating system connected to the energy storage system, an air turbine system connected to the heating system, and a generator 1 connected to the air turbine system, which are coaxially connected in sequence; the steam turbine unit 3 is connected to the coal-fired power generation subsystem. The invention ensures the stable and safe operation of the boiler and the low-load operation of the steam turbine, and also recovers excess energy to meet the system's wide-load, deep peak-shaving, and fast load demand response operating requirements.

[0006] CN114738061A discloses a solar-assisted compressed air energy storage system coupled with a Kalina cycle, comprising a compressed air energy storage system, a solar-assisted heating system, and a Kalina cycle system, wherein the compressed air energy storage system is composed of a compressor, a cooler, an air storage chamber, an expander, a heat exchanger, a cold storage tank, and a heat storage tank; the solar-assisted heating system is composed of a solar collector, a heat storage tank, and a cold storage tank; and the Kalina cycle system is composed of an evaporator, a separator, a steam turbine, a condenser, a pump, and a heat exchanger; part of the heat transfer oil that flows back to the cold storage tank of the solar-assisted heating system after heat exchange is used to separate the mixed liquid in the Kalina cycle, and the compression heat that is not used by the energy storage system is used to heat the liquid ammonia at the outlet of the first steam turbine; a pump and a second steam turbine are added, and the liquid ammonia at the outlet of the second steam turbine is mixed with the dilute ammonia water from the separator to absorb the waste heat of the air at the tail of the expander, so as to make full use of the waste heat of the system, realize the cascade utilization of energy, and improve the energy storage efficiency of the system.

[0007] The above-mentioned device systems all use thermal oil to store heat, but there is a safety hazard that high-pressure air may leak into the thermal oil, causing fire and explosion.

[0008] Therefore, it is of great significance to develop a liquid compressed air energy storage device system that can prevent high-pressure air from leaking into the thermal oil and greatly improve the safety of thermal oil heat storage. Summary of the invention

[0009] In view of the problems existing in the prior art, the present invention provides a device system and method for storing liquid compressed air energy and heat, which adopts polyethylene glycol and molten salt as two heat exchange media as intermediate heat media, and adopts thermal oil as heat storage medium to solve the problem of leakage of thermal oil from high-temperature air, while improving the safety of the device system without significantly increasing the cost of compressed air energy storage; the device system realizes the storage and recycling of heat and cold, and is suitable for large-scale industrial applications.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a liquid compressed air energy storage and heat storage device system, the device system comprising a first air compression device, a first intermediate cooling device, a second intermediate cooling device, a second air compression device, a third intermediate cooling device, a fourth intermediate cooling device, a cryogenic device, a low-temperature turbine, a gas-liquid separation device, a liquid compressed air storage device, a recooling device, a first heating device, a second heating device, a first air turbine, a third heating device, a fourth heating device and a second air turbine connected in sequence;

[0012] The device system also includes a first molten salt heat exchange device and a first polyethylene glycol heat exchange device;

[0013] The first molten salt heat exchange device is cyclically connected to the first intermediate cooling device; the first molten salt heat exchange device is also cyclically connected to the third intermediate cooling device;

[0014] The first polyethylene glycol heat exchange device is circularly connected to the second intermediate cooling device; the first polyethylene glycol heat exchange device is also circularly connected to the fourth intermediate cooling device.

[0015] In the heat storage and heat release process of the liquid compressed air energy storage device system described in the present invention, a secondary circuit is used for both heat storage and heat release processes, and polyethylene glycol is used as the intermediate heat medium in the low temperature section, molten salt is used as the intermediate heat medium in the high temperature section, and heat transfer oil is used as the heat storage medium. The primary circuit is air-polyethylene glycol heat exchange and air-molten salt heat exchange, and the secondary circuit is polyethylene glycol-heat transfer oil heat exchange and molten salt-heat transfer oil heat exchange, which solves the problem of leakage of high-temperature air to heat transfer oil, and greatly improves the safety of the system. In the present invention, polyethylene glycol is used as the intermediate heat medium in the low temperature section. Compared with water heat medium, the pipeline and heat exchanger do not need high pressure; compared with ethylene glycol, polyethylene glycol has higher flash point and boiling point, so the use temperature is higher and safer; molten salt is used as the intermediate heat medium in the high temperature section. Compared with water heat medium, the pipeline and heat exchanger do not need high pressure. Moreover, polyethylene glycol and molten salt are used as intermediate heat mediums, which only circulate in a closed loop, do not require additional storage devices, and will not significantly increase investment.

[0016] The fourth intermediate cooling device in the present invention is also connected to the deep cooling device, the low-temperature turbine, the gas-liquid separation device, the liquid compressed air storage device and the recooling device in sequence. Compared with other compressed air energy storage devices, the storage volume of liquid compressed air is greatly reduced, so that the cold energy in the entire device system can be stored and recycled.

[0017] Preferably, the first air compression device and the second air compression device are coaxially connected to the electric motor.

[0018] Preferably, the low-temperature turbine is coaxially connected to the first generator.

[0019] In the present invention, the compressed air at the outlet of the fourth intermediate cooling device passes through a deep cooling device and becomes compressed air with a temperature of -165 to -175°C and a pressure of 10 MPa, and enters the low-temperature turbine to perform work, driving the first generator to generate electricity, thereby rationally utilizing the cooling capacity of the compressed air.

[0020] Preferably, the first air turbine and the second air turbine are coaxially connected to the second generator.

[0021] Preferably, a liquid air pump is provided between the liquid compressed air storage device and the cooling device.

[0022] Preferably, a first conveying device is provided on the outlet pipeline of the first molten salt heat exchange device.

[0023] Preferably, a second conveying device is provided on the outlet pipeline of the first polyethylene glycol heat exchange device.

[0024] Preferably, the device system also includes a cold storage device.

[0025] Preferably, the cold storage device is cyclically connected to a deep cooling device; the cold storage device is also cyclically connected to a cooling regeneration device.

[0026] In the present invention, the heat exchange medium circulating in the cold storage device, the deep cooling device and the recooling device includes liquid or gas.

[0027] Preferably, the device system also includes a second molten salt heat exchange device and a second polyethylene glycol heat exchange device.

[0028] Preferably, the second molten salt heat exchange device is connected in a circulation manner to the second heating device; the second molten salt heat exchange device is also connected in a circulation manner to the fourth heating device.

[0029] Preferably, the second polyethylene glycol heat exchange device is connected in a circulation manner to the first heating device; the second polyethylene glycol heat exchange device is also connected in a circulation manner to the third heating device.

[0030] Preferably, the device system further includes a first thermal oil storage device and a second thermal oil storage device.

[0031] Preferably, the first thermal oil storage device is connected to the second molten salt heat exchange device and the second polyethylene glycol heat exchange device in sequence.

[0032] Preferably, the second thermal oil storage device is connected to the first polyethylene glycol heat exchange device and the first molten salt heat exchange device in sequence.

[0033] Preferably, a third conveying device is provided on the outlet pipeline of the second molten salt heat exchange device.

[0034] Preferably, a fourth conveying device is provided on the outlet pipeline of the second polyethylene glycol heat exchange device.

[0035] Preferably, a fifth conveying device is provided on the outlet pipeline of the first thermal oil storage device.

[0036] Preferably, a sixth conveying device is provided on the outlet pipeline of the second thermal oil storage device.

[0037] In a second aspect, the present invention further provides a method for storing and heat storing energy using liquid compressed air, the method being carried out using the device system for storing and heat storing energy using liquid compressed air as described in the first aspect; the method includes an energy storage process and an energy release process.

[0038] The energy storage process includes: air enters the first air compression device to become the first compressed air, the first compressed air enters the first intermediate cooling device to transfer heat to the molten salt in the first molten salt heat exchange device, enters the second intermediate cooling device to transfer heat to the polyethylene glycol in the first polyethylene glycol heat exchange device, enters the second air compression device, and becomes the second compressed air; the second compressed air enters the third intermediate cooling device to transfer heat to the molten salt in the first molten salt heat exchange device, enters the fourth intermediate cooling device to transfer heat to the polyethylene glycol in the first polyethylene glycol heat exchange device, enters the deep cooling device to be cooled, and then enters the low-temperature turbine to drive the first generator to generate electricity;

[0039] The compressed air at the outlet of the low-temperature turbine enters the gas-liquid separation device to separate the non-condensable gas. The non-condensable gas is discharged after releasing the cold in the cryogenic device, and the liquid compressed air enters the liquid compressed air storage device for storage;

[0040] The molten salt is divided into two paths through the first conveying device, and enters the first intermediate cooling device to absorb the heat of the first compressed air, enters the third intermediate cooling device to absorb the heat of the second compressed air, and then returns to the first molten salt heat exchange device to form a closed loop;

[0041] The polyethylene glycol is divided into two paths through the second conveying device, and enters the second intermediate cooling device to absorb the heat of the first compressed air, enters the fourth intermediate cooling device to absorb the heat of the second compressed air, and then returns to the first polyethylene glycol heat exchange device to form a closed loop;

[0042] The heat transfer oil in the second heat transfer oil storage device is transported to the first polyethylene glycol heat exchange device through the sixth transport device to absorb the heat of polyethylene glycol, then enters the first molten salt heat exchange device to absorb the heat of molten salt, and then enters the first heat transfer oil storage device for storage.

[0043] Preferably, during the energy storage process, the electric motor drives the first air compression device and the second air compression device to compress air.

[0044] Preferably, the energy release process includes: the liquid compressed air stored in the liquid compressed air storage device enters the recooling device to be heated after passing through the liquid air pump, enters the first heating device to absorb the heat of the polyethylene glycol in the second polyethylene glycol heat exchange device, enters the second heating device to absorb the heat of the molten salt in the second molten salt heat exchange device, enters the first air turbine to do work; the air after doing work enters the third heating device to absorb the heat of the polyethylene glycol in the second polyethylene glycol heat exchange device, enters the fourth heating device to absorb the heat of the molten salt in the second molten salt heat exchange device, enters the second air turbine to do work, and the air after doing work is discharged into the atmosphere;

[0045] The polyethylene glycol is divided into two paths through the fourth conveying device, and enters the first heating device to transfer heat to the liquid compressed air at the outlet of the cooling device, and enters the third heating device to transfer heat to the liquid compressed air at the outlet of the first air turbine, and then returns to the second polyethylene glycol heat exchange device to form a closed loop;

[0046] The molten salt is divided into two paths through the third conveying device, and enters the second heating device to transfer heat to the liquid compressed air at the outlet of the first heating device, and enters the fourth heating device to transfer heat to the liquid compressed air at the outlet of the third heating device, and then returns to the second molten salt heat exchange device to form a closed loop;

[0047] The heat transfer oil in the first heat transfer oil storage device is transported to the second molten salt heat exchange device through the fifth transport device to transfer heat to the molten salt, and then enters the second polyethylene glycol heat exchange device to transfer heat to polyethylene glycol. The heat transfer oil after heat release enters the second heat transfer oil storage device for storage.

[0048] Preferably, during the energy release process, the first air turbine and the second air turbine drive the second generator to generate electricity.

[0049] Preferably, the air entering the first air compression device is dry air.

[0050] In the present invention, it is preferred that the drying gas is a gas from which moisture and carbon dioxide have been removed.

[0051] Preferably, the pressure of the liquid compressed air entering the liquid compressed air storage device is 0.5 to 0.9 MPa, for example, it can be 0.5 MPa, 0.55 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa or 0.9 MPa, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable; the temperature is -180 to -170°C, for example, it can be -180°C, -178°C, -175°C, -173°C or -170°C, etc., but it is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0052] As a preferred technical solution of the present invention, the method includes an energy storage process and an energy release process;

[0053] The energy storage process includes: the gas from which water and carbon dioxide are removed enters the first air compression device to become the first compressed air; the first compressed air enters the first intermediate cooling device to transfer heat to the molten salt in the first molten salt heat exchange device, enters the second intermediate cooling device to transfer heat to the polyethylene glycol in the first polyethylene glycol heat exchange device, enters the second air compression device to become the second compressed air; the second compressed air enters the third intermediate cooling device to transfer heat to the molten salt in the first molten salt heat exchange device, enters the fourth intermediate cooling device to transfer heat to the polyethylene glycol in the first polyethylene glycol heat exchange device, enters the deep cooling device to be cooled, and then enters the low-temperature turbine to drive the first generator to generate electricity;

[0054] The compressed air at the outlet of the low-temperature turbine enters the gas-liquid separation device to separate the non-condensable gas. The non-condensable gas releases the cold in the cryogenic device and is discharged. The heat exchange medium that absorbs the cold in the cryogenic device enters the cold storage device for storage. The liquid compressed air with a pressure of 0.5 to 0.9 MPa and a temperature of -180 to -170°C enters the liquid compressed air storage device for storage.

[0055] The molten salt is divided into two paths through the first conveying device, and enters the first intermediate cooling device to absorb the heat of the first compressed air, enters the third intermediate cooling device to absorb the heat of the second compressed air, and then returns to the first molten salt heat exchange device to form a closed loop;

[0056] The polyethylene glycol is divided into two paths through the second conveying device, and enters the second intermediate cooling device to absorb the heat of the first compressed air, enters the fourth intermediate cooling device to absorb the heat of the second compressed air, and then returns to the first polyethylene glycol heat exchange device to form a closed loop;

[0057] The heat transfer oil in the second heat transfer oil storage device is transported to the first polyethylene glycol heat exchange device by the sixth transport device to absorb the heat of polyethylene glycol, then enters the first molten salt heat exchange device to absorb the heat of molten salt, and then enters the first heat transfer oil storage device for storage;

[0058] During the energy storage process, the electric motor drives the first air compression device and the second air compression device to compress air.

[0059] The energy release process includes: the liquid compressed air stored in the liquid compressed air storage device enters the recooling device to be heated after passing through the liquid air pump, enters the first heating device to absorb the heat of the polyethylene glycol in the second polyethylene glycol heat exchange device, enters the second heating device to absorb the heat of the molten salt in the second molten salt heat exchange device, enters the first air turbine to do work; the air after doing work enters the third heating device to absorb the heat of the polyethylene glycol in the second polyethylene glycol heat exchange device, enters the fourth heating device to absorb the heat of the molten salt in the second molten salt heat exchange device, enters the second air turbine to do work, and the air after doing work is discharged into the atmosphere; the heat exchange medium after releasing heat in the recooling device is returned to the cold storage device for storage;

[0060] The polyethylene glycol is divided into two paths through the fourth conveying device, and enters the first heating device to transfer heat to the liquid compressed air at the outlet of the cooling device, and enters the third heating device to transfer heat to the liquid compressed air at the outlet of the first air turbine, and then returns to the second polyethylene glycol heat exchange device to form a closed loop;

[0061] The molten salt is divided into two paths through the third conveying device, and enters the second heating device to transfer heat to the liquid compressed air at the outlet of the first heating device, and enters the fourth heating device to transfer heat to the liquid compressed air at the outlet of the third heating device, and then returns to the second molten salt heat exchange device to form a closed loop;

[0062] The heat transfer oil in the first heat transfer oil storage device is transported to the second molten salt heat exchange device through the fifth transport device to transfer heat to the molten salt, and then enters the second polyethylene glycol heat exchange device to transfer heat to polyethylene glycol. The heat transfer oil after heat release enters the second heat transfer oil storage device for storage;

[0063] During the energy release process, the first air turbine and the second air turbine drive the second generator to generate electricity.

[0064] Compared with the prior art, the present invention has at least the following beneficial effects:

[0065] (1) In the liquid compressed air energy storage and heat storage device system provided by the present invention, both the heat storage and heat release processes adopt a secondary circuit, polyethylene glycol is used as the intermediate heat medium in the low temperature section, molten salt is used as the intermediate heat medium in the high temperature section, and heat transfer oil is used as the heat storage medium, which solves the problem of leakage of heat transfer oil in high temperature air, and greatly improves the safety of the system;

[0066] (2) The polyethylene glycol and molten salt in the liquid compressed air energy storage and heat storage device system provided by the present invention serve as intermediate heat media and only flow in a closed cycle without heat storage, which will not significantly increase investment;

[0067] (3) The liquid compressed air energy storage and heat storage device system provided by the present invention realizes the storage and recycling of heat and cold. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 It is a structural schematic diagram of the liquid compressed air energy and heat storage device system provided by the present invention.

[0069] In the figure: 1-first air compression device; 2-second air compression device; 3-motor; 4-first intermediate cooling device; 5-second intermediate cooling device; 6-third intermediate cooling device; 7-fourth intermediate cooling device; 8-first molten salt heat exchange device; 9-first polyethylene glycol heat exchange device; 10-first thermal oil storage device; 11-second thermal oil storage device; 12-cryogenic device; 13-cold storage device; 14-low temperature turbine; 15-first generator; 16-gas-liquid separation device; 17-liquid compressed air Gas storage device; 18-liquid air pump; 19-recooling device; 20-first air turbine; 21-second air turbine; 22-second generator; 23-first heating device; 24-second heating device; 25-third heating device; 26-fourth heating device; 27-second polyethylene glycol heat exchange device; 28-second molten salt heat exchange device; 29-first conveying device; 30-second conveying device; 31-sixth conveying device; 32-fifth conveying device; 33-fourth conveying device; 34-third conveying device. DETAILED DESCRIPTION

[0070] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0071] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0072] It should be understood that, in the description of the present invention, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0073] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0074] Those skilled in the art should understand that the present invention necessarily includes necessary pipelines, conventional valves and general pump equipment for realizing a complete process, but the above content does not belong to the main inventive point of the present invention. Those skilled in the art can add layouts on their own based on the process flow and equipment structure selection, and the present invention does not make special requirements and specific limitations on this.

[0075] As a specific embodiment of the present invention, a liquid compressed air energy storage and heat storage device system is provided, and its structural schematic diagram is as follows: Figure 1 shown.

[0076] The device system comprises a first air compressing device 1, a first intermediate cooling device 4, a second intermediate cooling device 5, a second air compressing device 2, a third intermediate cooling device 6, a fourth intermediate cooling device 7, a cryogenic device 12, a low-temperature turbine 14, a gas-liquid separation device 16, a liquid compressed air storage device 17, a recooling device 19, a first heating device 23, a second heating device 24, a first air turbine 20, a third heating device 25, a fourth heating device 26 and a second air turbine 21 connected in sequence;

[0077] The device system also includes a first molten salt heat exchange device 8 and a first polyethylene glycol heat exchange device 9;

[0078] The first molten salt heat exchange device 8 is cyclically connected to the first intermediate cooling device 4; the first molten salt heat exchange device 8 is also cyclically connected to the third intermediate cooling device 6;

[0079] The first polyethylene glycol heat exchange device 9 is connected in a circulation manner to the second intermediate cooling device 5 ; the first polyethylene glycol heat exchange device 9 is also connected in a circulation manner to the fourth intermediate cooling device 7 .

[0080] The first air compressing device 1 and the second air compressing device 2 are coaxially connected with the motor 3;

[0081] The low temperature turbine 14 is coaxially connected with the first generator 15;

[0082] The first air turbine 20 and the second air turbine 21 are coaxially connected with the second generator 22;

[0083] A liquid air pump 18 is provided between the liquid compressed air storage device 17 and the cooling device 19;

[0084] A first conveying device 29 is provided on the outlet pipeline of the first molten salt heat exchange device 8;

[0085] A second conveying device 30 is arranged on the outlet pipeline of the first polyethylene glycol heat exchange device 9 .

[0086] The device system also includes a cold storage device 13;

[0087] The cold storage device 13 is connected in a circulation manner to the deep cooling device 12 ; the cold storage device 13 is also connected in a circulation manner to the cooling device 19 .

[0088] The device system also includes a second molten salt heat exchange device 28 and a second polyethylene glycol heat exchange device 27;

[0089] The second molten salt heat exchange device 28 is cyclically connected to the second heating device 24; the second molten salt heat exchange device 28 is also cyclically connected to the fourth heating device 26;

[0090] The second polyethylene glycol heat exchange device 27 is connected in a circulation manner to the first heating device 23 ; the second polyethylene glycol heat exchange device 27 is also connected in a circulation manner to the third heating device 25 .

[0091] The device system further includes a first thermal oil storage device 10 and a second thermal oil storage device 11;

[0092] The first heat transfer oil storage device 10 is connected in sequence to the second molten salt heat exchange device 28 and the second polyethylene glycol heat exchange device 27;

[0093] The second heat transfer oil storage device 11 is connected to the first polyethylene glycol heat exchange device 9 and the first molten salt heat exchange device 8 in sequence.

[0094] A third conveying device 34 is provided on the outlet pipeline of the second molten salt heat exchange device 28;

[0095] A fourth conveying device 33 is provided on the outlet pipeline of the second polyethylene glycol heat exchange device 27;

[0096] A fifth delivery device 32 is provided on the outlet pipeline of the first thermal oil storage device 10;

[0097] A sixth conveying device 31 is disposed on the outlet pipeline of the second thermal oil storage device 11 .

[0098] As a specific embodiment of the present invention, a method for storing and heat storing liquid compressed air is also provided, and the method is carried out using the above-mentioned liquid compressed air energy storage and heat storage device system; the method includes an energy storage process and an energy release process.

[0099] The energy storage process includes: the gas with a temperature of 20°C and a pressure of 0.1MPa and dehydrated with carbon dioxide enters the first air compression device 1 to become the first compressed air with a temperature of 370°C and a pressure of 1.2MPa, the first compressed air enters the first intermediate cooling device 4 to transfer heat to the molten salt in the first molten salt heat exchange device 8, and after the temperature is reduced to 180°C, enters the second intermediate cooling device 5 to transfer heat to the polyethylene glycol in the first polyethylene glycol heat exchange device 9, and the temperature is reduced to 55°C, and enters the second air compression device 2 to become the temperature of 370°C and the pressure of 10MPa. Second compressed air; the second compressed air enters the third intermediate cooling device 6 to transfer heat to the molten salt in the first molten salt heat exchange device 8, and after the temperature is reduced to 180°C, enters the fourth intermediate cooling device 7 to transfer heat to the polyethylene glycol in the first polyethylene glycol heat exchange device 9, and the temperature is reduced to 55°C, enters the deep cooling device 12 to be cooled, and the temperature is reduced to -165°C, and then enters the low-temperature turbine 14 to drive the first generator 15 to generate electricity, and the temperature is reduced to -170°C, and the pressure is reduced to 0.8MPa; the heat exchange medium in the deep cooling device 12 absorbs the heat of the compressed air and transfers it to the cold storage device 13;

[0100] The compressed air at the outlet of the low-temperature turbine 14 enters the gas-liquid separation device 16 to separate the non-condensable gas. The non-condensable gas is discharged after releasing the cold in the cryogenic device 12. The liquid compressed air with a temperature of -170°C and a pressure of 0.8MPa enters the liquid compressed air storage device 17 for storage;

[0101] The molten salt with a temperature of 170°C is divided into two paths through the first conveying device 29, and enters the first intermediate cooling device 4 to absorb the heat of the first compressed air, and enters the third intermediate cooling device 6 to absorb the heat of the second compressed air. After the temperature rises to 360°C, it returns to the first molten salt heat exchange device 8 to form a closed loop;

[0102] The polyethylene glycol at a temperature of 50°C is divided into two paths through the second conveying device 30, and enters the second intermediate cooling device 5 to absorb the heat of the first compressed air, and enters the fourth intermediate cooling device 7 to absorb the heat of the second compressed air and raise the temperature to 170°C, and then returns to the first polyethylene glycol heat exchange device 9 to form a closed loop;

[0103] The heat transfer oil with a temperature of 50°C in the second heat transfer oil storage device 11 is transported to the first polyethylene glycol heat exchange device 9 by the sixth transport device 31 to absorb the heat of polyethylene glycol, then enters the first molten salt heat exchange device 8 to absorb the heat of molten salt and the temperature rises to 355°C before entering the first heat transfer oil storage device 10 for storage;

[0104] During the energy storage process, the motor 3 drives the first air compressing device 1 and the second air compressing device 2 to compress air.

[0105] The energy release process includes: the liquid compressed air stored in the liquid compressed air storage device 17 with a temperature of -170°C and a pressure of 0.8MPa is increased to 17.5MPa by the liquid air pump 18, enters the cooling device 19 to be heated to 35°C, and the liquid compressed air becomes gaseous, enters the first heating device 23 to absorb the heat of the polyethylene glycol in the second polyethylene glycol heat exchange device 27, enters the second heating device 24 to absorb the heat of the molten salt in the second molten salt heat exchange device 28, and the temperature is increased to 340°C, and enters the first air permeation device 23. The air with a pressure of 1.1 MPa and a temperature of 40°C after doing work enters the third heating device 25 to absorb the heat of polyethylene glycol in the second polyethylene glycol heat exchange device 27, enters the fourth heating device 26 to absorb the heat of molten salt in the second molten salt heat exchange device 28, and the temperature rises to 340°C, and enters the second air turbine 21 to do work. The air with a pressure of 0.105 MPa and a temperature of 65°C after doing work is discharged into the atmosphere; the heat exchange medium in the cooling device 19 absorbs the cold of the liquid compressed air and transfers it to the cold storage device 13;

[0106] The polyethylene glycol at a temperature of 170°C is divided into two paths through the fourth conveying device 33, and enters the first heating device 23 to transfer heat to the liquid compressed air at the outlet of the cooling device 19, and enters the third heating device 25 to transfer heat to the liquid compressed air at the outlet of the first air turbine 20. After the temperature is reduced to 45°C, it returns to the second polyethylene glycol heat exchange device 27 to form a closed loop.

[0107] The molten salt with a temperature of 350°C is divided into two paths through the third conveying device 34, and enters the second heating device 24 to transfer heat to the liquid compressed air at the outlet of the first heating device 23, and enters the fourth heating device 26 to transfer heat to the liquid compressed air at the outlet of the third heating device 25. After the temperature is reduced to 170°C, it returns to the second molten salt heat exchange device 28 to form a closed loop;

[0108] The heat transfer oil with a temperature of 355°C in the first heat transfer oil storage device 10 is transported to the second molten salt heat exchange device 28 through the fifth transport device 32 to transfer heat to the molten salt, and then enters the second polyethylene glycol heat exchange device 27 to transfer heat to polyethylene glycol. After heat release, the heat transfer oil with a temperature of 50°C enters the second heat transfer oil storage device 11 for storage;

[0109] During the energy release process, the first air turbine 20 and the second air turbine 21 drive the second generator 22 to generate electricity.

[0110] In summary, the liquid compressed air energy storage and heat storage device system provided by the present invention adopts polyethylene glycol as the intermediate heat medium in the low-temperature section, adopts molten salt as the intermediate heat medium in the high-temperature section, and adopts heat transfer oil as the heat storage medium, which solves the problem of leakage of the heat transfer oil from the high-temperature air, and greatly improves the safety of the system; the polyethylene glycol and molten salt serve as intermediate heat media, which only flow in a closed cycle and do not store heat, and will not significantly increase the investment; and the storage and recycling of heat and cold are realized, which has a prospect of large-scale industrial promotion and application.

[0111] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0112] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A liquid compressed air energy storage and heat storage device system, characterized in that: The device system includes a first air compression device, a first intermediate cooling device, a second intermediate cooling device, a second air compression device, a third intermediate cooling device, a fourth intermediate cooling device, a cryogenic device, a low-temperature turbine, a gas-liquid separation device, a liquid compressed air storage device, a recooling device, a first heating device, a second heating device, a first air turbine, a third heating device, a fourth heating device and a second air turbine connected in sequence; The device system also includes a first molten salt heat exchange device and a first polyethylene glycol heat exchange device; The first molten salt heat exchange device is cyclically connected to the first intermediate cooling device; the first molten salt heat exchange device is also cyclically connected to the third intermediate cooling device; The first polyethylene glycol heat exchange device is cyclically connected to the second intermediate cooling device; the first polyethylene glycol heat exchange device is also cyclically connected to the fourth intermediate cooling device; The device system also includes a second molten salt heat exchange device and a second polyethylene glycol heat exchange device; The second molten salt heat exchange device is cyclically connected to the second heating device; The second molten salt heat exchange device is also cyclically connected to the fourth heating device; The second polyethylene glycol heat exchange device is cyclically connected to the first heating device; The second polyethylene glycol heat exchange device is also cyclically connected to the third heating device; The device system also includes a first thermal oil storage device and a second thermal oil storage device; The first heat transfer oil storage device is connected in sequence to a fifth conveying device, a second molten salt heat exchange device, a second polyethylene glycol heat exchange device and a second heat transfer oil storage device arranged on its outlet pipeline; The second heat transfer oil storage device is connected in sequence to the sixth conveying device, the first polyethylene glycol heat exchange device, the first molten salt heat exchange device and the first heat transfer oil storage device arranged on its outlet pipeline.

2. The device system according to claim 1, characterized in that: The first air compression device and the second air compression device are coaxially connected to the electric motor; The low temperature turbine is coaxially connected to the first generator; The first air turbine and the second air turbine are coaxially connected to the second generator; A liquid air pump is provided between the liquid compressed air storage device and the cooling device; A first conveying device is provided on the outlet pipeline of the first molten salt heat exchange device; A second conveying device is arranged on the outlet pipeline of the first polyethylene glycol heat exchange device.

3. The device system according to claim 1, characterized in that: The device system also includes a cold storage device; The cold storage device is cyclically connected with the deep cooling device; The cold storage device is also cyclically connected with the cooling device.

4. The device system according to claim 1, characterized in that: A third conveying device is provided on the outlet pipeline of the second molten salt heat exchange device; A fourth conveying device is arranged on the outlet pipeline of the second polyethylene glycol heat exchange device.

5. A method for storing energy and heat using liquid compressed air, characterized in that: The method is carried out using the liquid compressed air energy storage and heat storage device system described in any one of claims 1 to 4; the method includes an energy storage process and an energy release process.

6. The method according to claim 5, characterized in that The energy storage process includes: air enters the first air compression device to become the first compressed air, the first compressed air enters the first intermediate cooling device to transfer heat to the molten salt in the first molten salt heat exchange device, enters the second intermediate cooling device to transfer heat to the polyethylene glycol in the first polyethylene glycol heat exchange device, enters the second air compression device, and becomes the second compressed air; the second compressed air enters the third intermediate cooling device to transfer heat to the molten salt in the first molten salt heat exchange device, enters the fourth intermediate cooling device to transfer heat to the polyethylene glycol in the first polyethylene glycol heat exchange device, enters the deep cooling device to be cooled, and then enters the low-temperature turbine to drive the first generator to generate electricity; The compressed air at the outlet of the low-temperature turbine enters the gas-liquid separation device to separate the non-condensable gas. The non-condensable gas releases cold in the cryogenic device and is discharged. The heat exchange medium that absorbs cold in the cryogenic device enters the cold storage device for storage, and the liquid compressed air enters the liquid compressed air storage device for storage. The molten salt is divided into two paths through the first conveying device, and enters the first intermediate cooling device to absorb the heat of the first compressed air, enters the third intermediate cooling device to absorb the heat of the second compressed air, and then returns to the first molten salt heat exchange device to form a closed loop; The polyethylene glycol is divided into two paths through the second conveying device, and enters the second intermediate cooling device to absorb the heat of the first compressed air, enters the fourth intermediate cooling device to absorb the heat of the second compressed air, and then returns to the first polyethylene glycol heat exchange device to form a closed loop; The heat transfer oil in the second heat transfer oil storage device is transported to the first polyethylene glycol heat exchange device by the sixth transport device to absorb the heat of polyethylene glycol, then enters the first molten salt heat exchange device to absorb the heat of molten salt, and then enters the first heat transfer oil storage device for storage; During the energy storage process, the electric motor drives the first air compression device and the second air compression device to compress air.

7. The method according to claim 5, characterized in that The energy release process includes: the liquid compressed air stored in the liquid compressed air storage device enters the recooling device to be heated after passing through the liquid air pump, enters the first heating device to absorb the heat of the polyethylene glycol in the second polyethylene glycol heat exchange device, enters the second heating device to absorb the heat of the molten salt in the second molten salt heat exchange device, enters the first air turbine to do work; the air after doing work enters the third heating device to absorb the heat of the polyethylene glycol in the second polyethylene glycol heat exchange device, enters the fourth heating device to absorb the heat of the molten salt in the second molten salt heat exchange device, enters the second air turbine to do work, and the air after doing work is discharged into the atmosphere; the heat exchange medium after releasing heat in the recooling device is returned to the cold storage device for storage; The polyethylene glycol is divided into two paths through the fourth conveying device, and enters the first heating device to transfer heat to the liquid compressed air at the outlet of the cooling device, and enters the third heating device to transfer heat to the liquid compressed air at the outlet of the first air turbine, and then returns to the second polyethylene glycol heat exchange device to form a closed loop; The molten salt is divided into two paths through the third conveying device, and enters the second heating device to transfer heat to the liquid compressed air at the outlet of the first heating device, and enters the fourth heating device to transfer heat to the liquid compressed air at the outlet of the third heating device, and then returns to the second molten salt heat exchange device to form a closed loop; The heat transfer oil in the first heat transfer oil storage device is transported to the second molten salt heat exchange device through the fifth transport device to transfer heat to the molten salt, and then enters the second polyethylene glycol heat exchange device to transfer heat to polyethylene glycol. The heat transfer oil after heat release enters the second heat transfer oil storage device for storage; During the energy release process, the first air turbine and the second air turbine drive the second generator to generate electricity.

8. The method according to claim 6, characterized in that The air entering the first air compression device is dry air; The pressure of the liquid compressed air entering the liquid compressed air storage device is 0.5 to 0.9 MPa, and the temperature is -180 to -170°C.

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