Compressed air energy storage device

Abstract

Provided is a technology capable of adjusting supply and demand of electric power. A compressed air energy storage device 100 comprises: air compressors 6, 7 that generate compressed air; heat exchangers 24, 25 that exchange heat between the compressed air and a heat storage medium; a pressure accumulation tank 8 that stores the compressed air that has undergone heat exchange in the heat exchangers 24, 25; a heat storage tank 21 that stores the heat storage medium that has undergone heat exchange in the heat exchangers 24, 25; a heat exchanger 32 that generates low-pressure steam by heating water through heat exchange with the heat storage medium; a steam compressor 41 that generates high-temperature steam by compressing the low-pressure steam; generators 12, 13 that generate electric power; and expanders 10, 11 that drive the generators 12, 13 by means of the compressed air or the high-temperature steam. The compressed air energy storage device supplies one or more of the compressed air, the high-temperature steam, and the electric power.

Description

Compressed Air Energy Storage Device

[0001] The present invention relates to a compressed air energy storage device.

[0002] Renewable energy power generation such as wind power generation and solar power generation depends on weather conditions, and therefore the amount of power generated can fluctuate and become unstable. A compressed air energy storage (CAES) system is known as a system that can level out power generation output to address such fluctuations.

[0003] A compressed air energy storage device (CAES device) using this CAES system operates, for example, when generating electricity using a solar power generation system, by operating a compressor during the daytime when surplus electricity is generated, and storing electrical energy as compressed air in an accumulator tank, and when electricity is needed, the compressed air is used to drive an expander to operate a generator, thereby generating electrical energy and leveling out output.

[0004] In such CAES devices, for example, Patent Document 1 discloses a compressed air energy storage device that stores compressed air in tanks of different sizes according to the cycle of power fluctuations.

[0005] On the other hand, equipment such as pneumatic systems (air compressors) and boilers that are commonly used as power sources in factories use a large proportion of energy, such as electricity and fossil fuels, has a large energy loss in the form of exhaust heat, and emits a large amount of carbon dioxide.

[0006] As an example of a device that uses the exhaust heat of other equipment in a boiler, Patent Document 2 discloses a device that uses the exhaust heat of a ship's engine to heat boiler water and use the steam as a heating source on board the ship.

[0007] Japanese Patent No. 6368577 Japanese Patent Application Laid-Open No. 2015-17771

[0008] However, Patent Documents 1 and 2 do not disclose adjusting the supply and demand of electricity by combining an air compressor and a boiler.

[0009] Therefore, an object of the present invention is to provide a technique capable of adjusting power supply and demand.

[0010] In order to solve the above problems, one representative compressed air energy storage device of the present invention includes an air compressor that generates compressed air, a first heat exchanger that exchanges heat between the compressed air and a heat storage medium, a pressure storage tank that stores the compressed air that has been heat exchanged in the first heat exchanger, a heat storage tank that stores the heat storage medium that has been heat exchanged in the first heat exchanger, a low-pressure steam generation device that generates low-pressure steam by heating water through heat exchange with the heat storage medium, a steam compressor that compresses the low-pressure steam to generate high-temperature steam, a generator that generates electricity, and an expander that drives the generator with compressed air or high-temperature steam, and supplies one or more of compressed air, high-temperature steam, and electricity.

[0011] According to the present invention, it is possible to adjust the supply and demand of electricity.

[0012] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0013] FIG. 1 is a diagram showing an example of a schematic configuration of a compressed air energy storage device of Example 1. FIG. 2 is a diagram showing an example of a schematic configuration of a compressed air energy storage device of Example 2. FIG. 3 is a diagram showing an example of a schematic configuration of a compressed air energy storage device of Example 3. FIG. 4 is a diagram showing an example of a schematic configuration of a compressed air energy storage device of Example 4. FIG. 5 is a diagram showing an example of a schematic configuration of a compressed air energy storage device of Example 5. FIG. 6 is a diagram showing an example of a schematic configuration of a compressed air energy storage device of Example 6. FIG. 1 is a flowchart of an operation control process executed by a control device of the compressed air energy storage device of Example 1.

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Like elements are designated by like reference numerals and similar descriptions will not be repeated.

[0015] FIG. 1 is a diagram illustrating an example of a schematic configuration of a compressed air energy storage device according to a first embodiment.

[0016] The compressed air energy storage device 100 includes an air pressure unit 1, a heat storage unit 2, a boiler unit 40, and a power generation unit 3.

[0017] The air pressure unit 1 includes motors (electric motors) 4 and 5, air compressors 6 and 7, and an accumulator tank 8. The heat storage unit 2 includes a high-temperature side heat storage tank 21 and a low-temperature side heat storage tank 22 containing a heat storage medium such as water, and heat exchangers 24 and 25. The boiler unit 40 mainly includes a steam compressor 41. The power generation unit 3 includes expanders 10 and 11 and generators 12 and 13.

[0018] The motors 4 and 5 are connected to grid power 20 that utilizes renewable energy or the like via an inverter 9. The power generation unit 3 is also connected to the grid power 20 via a power conditioner 14. The grid power 20 is connected to a solar power generation device 18 and a wind power generation device 19.

[0019] The motor 4 is mechanically connected to an air compressor 6 that performs the low-stage compression stroke, and the motor 5 is mechanically connected to an air compressor 7 that performs the high-stage compression stroke. The air pressure unit 1 performs two-stage compression by performing the low-stage compression stroke and the high-stage compression stroke.

[0020] The intake port of the air compressor 6 is open to the atmosphere, and the discharge port of the air compressor 6 is connected to a heat exchanger 24 and then to an intake port of the air compressor 7. The discharge port of the air compressor 7 is connected to a heat exchanger 25 and then to an accumulator tank 8.

[0021] The suction port of the expander 10 is connected to the heat exchanger 26, and the discharge port of the expander 10 is connected to a pipe 92 connected to the heat exchanger 27 and a pipe 93 connected to the first pneumatic pipe 71. The pipe 92 has a valve 53, and the pipe 93 has a valve 54. The suction port of the expander 11 is connected to the heat exchanger 27, and the discharge port of the expander 11 is open to the atmosphere.

[0022] The heat exchanger 26 has a pipe 91 that connects to the accumulator tank 8, and the pipe 91 has a valve 52. The compressed air from the accumulator tank 8 flows into the heat exchanger 26.

[0023] The air-operated equipment 200 in the factory is connected to the accumulator tank 8 by a first air pressure pipe 71, and the first air pressure pipe 71 has a valve 51. Compressed air is supplied to the air-operated equipment 200 from the accumulator tank 8 via the first air pressure pipe 71.

[0024] The thermal storage unit 2 has a fluid circuit connecting the heat exchangers 24, 25, the thermal storage tank 21, the heat exchanger 32, and the thermal storage tank 22. The thermal storage medium exchanges heat with compressed air in the heat exchangers 24, 25 to recover the heat of compression, and the high-temperature thermal storage medium is stored in the thermal storage tank 21. Thereafter, the high-temperature thermal storage medium exchanges heat with low-temperature water in the heat exchanger 32 to generate low-pressure steam, and the low-temperature thermal storage medium is stored in the thermal storage tank 22. These fluid circuits are provided with pumps 28, 29 for transporting the thermal storage medium.

[0025] The boiler unit 40 includes a low-pressure steam generator 43, a gas-liquid separator 42, a low-temperature water circulation pump 44, a steam compressor 41, a pressure reducing valve 45, and a medium-temperature water heat recovery heat exchanger 47. The low-pressure steam generator 43 heats water flowing in from the gas-liquid separator 42 via a water supply pipe to generate low-pressure steam, and the generated low-pressure steam is compressed by the steam compressor 41 to generate high-temperature steam. The water supply pipe is provided with a pressure reducing valve 45.

[0026] In the low-pressure steam generating device 43, a portion of the low-temperature water is vaporized to become low-pressure steam below atmospheric pressure, the low-pressure steam and the low-temperature water are separated, the low-pressure steam is led to the steam compressor 41, and the low-temperature water is sent to the heat exchanger 32 by the low-temperature water circulation pump 44.

[0027] The steam compressor 41 is driven by a motor connected to the grid power 20 via an inverter 9, and compresses low-pressure steam to high-temperature and high-pressure steam to generate high-temperature steam. The high-temperature steam is supplied as a heat source for process heating and the like to steam-using equipment 300 in the factory.

[0028] The steam-using equipment 300 in the factory is connected to the steam compressor 41 by a first steam pipe 72, and the first steam pipe 72 has a valve 59. High-temperature steam is supplied to the steam-using equipment 300 from the steam compressor 41 via the first steam pipe 72.

[0029] The first steam pipe 72 is connected to pipes 94 and 95 which are connected to the heat exchangers 26 and 27, respectively, and to pipes 96 and 97 which are connected to the expanders 10 and 11, respectively. The pipes 94 and 95 have valves 55 and 56, respectively, and the pipes 94 and 95 have valves 57 and 58, respectively.

[0030] The power generation unit 3 includes expanders 10, 11 driven by compressed air, generators 12, 13 driven by the expanders 10, 11 to generate electricity, a power conditioner 14 to convert the voltage of the generated electricity, and heat exchangers 26, 27 to heat the compressed air at the inlets of the expanders 10, 11.

[0031] The expander 10 is responsible for the high-stage expansion stroke, and the expander 11 is responsible for the low-stage expansion stroke. The power generation unit 3 performs two-stage expansion by the high-stage expansion stroke and the low-stage expansion stroke.

[0032] The generator 12 is mechanically connected to the expander 10, and the generator 13 is mechanically connected to the expander 11. The generators 12 and 13 generate electricity (regenerate power) by being driven by the expanders 10 and 11. The generators 12 and 13 are connected to grid power 20 via a power conditioner 14, and return the regenerated power to the grid power 20.

[0033] The compressed air energy storage device 100 also includes a control device 80. The control device 80 controls the operation of the air compressors 6 and 7 and the steam compressor 41, and controls the opening and closing of valves 51, 52, 53, 54, 55, 56, 57, 58, and 59, in accordance with the demand for compressed air, the demand for high-temperature steam, and the demand for electricity in the factory.

[0034] The operation of the compressed air energy storage device 100 will now be described.

[0035] First, the operation of generating and storing compressed air will be described.

[0036] Motors 4 and 5 are connected to grid power 20 that utilizes renewable energy or the like and are driven by input power from the grid power 20. Two-stage compression is performed by air compressor 6 driven by motor 4 and air compressor 7 driven by motor 5.

[0037] The air compressor 6 draws in atmospheric air from its intake port and performs first-stage adiabatic compression. The compressed air discharged from the outlet of the air compressor 6 is heat exchanged with the heat storage medium in the heat exchanger 24, and then drawn into the air compressor 7.

[0038] The compressed air drawn into the air compressor 7 is further adiabatically compressed in a second stage by the air compressor 7, and becomes high-pressure and high-temperature. This compressed air exchanges heat with the heat storage medium in the heat exchanger 25.

[0039] The heat exchangers 24 and 25 exchange heat between the high-temperature compressed air and the heat storage medium that is branched off and supplied from the low-temperature side heat storage tank 22. This heat exchange raises the temperature of the low-temperature heat storage medium, which is then stored in the high-temperature side heat storage tank 21. On the other hand, the temperature of the compressed air that has exchanged heat with the heat storage medium in the heat exchanger 25 drops, and the compressed air flows into the pressure storage tank 8 and is stored therein.

[0040] With the above operation, the compressed air energy of the compressed air and the compressed heat generated when the compressed air is generated in the air pressure unit is stored in the pressure storage tank 8 for the compressed air and in the heat storage tank 21 for the compressed heat.

[0041] Next, the operation of supplying compressed air will be described.

[0042] The compressed air stored in the accumulator tank 8 is sequentially supplied from the accumulator tank 8 to the air-using equipment 200 .

[0043] As will be described later, the compressed air stored in the accumulator tank 8 is also used for power generation by expansion devices 10 and 11. Therefore, a pressure higher than the pressure used by the air-using devices 200 in the factory is stored in the accumulator tank 8. When the pressure in the accumulator tank 8 differs significantly from the pressure used by the air-using devices 200 in the factory, and the used pressure is lower, the valve 51 of the first air pressure pipe 71 supplying the air from the accumulator tank 8 to the air-using devices 200 is closed, and the valve 52 of the pipe 91 supplying the air to the heat exchanger 26 is opened. The compressed air passes through the heat exchanger 26 and flows into the expander 10. The expander 10 reduces the pressure of the compressed air to the pressure used by the air-using devices 200, and the valve 54 of the pipe 93 is opened to return the compressed air to the first air pressure pipe 71 and supply it to the air-using devices 200. At this time, the expander 10 drives the generator 12, which generates electricity.

[0044] When the pressure in the accumulator tank 8 drops and approaches the operating pressure of the air-using equipment 200, the valve 52 on the pipe 91 supplying the air to the heat exchanger 26 is closed, and the valve 51 on the first air pressure pipe 71 supplying the air from the accumulator tank 8 to the air-using equipment 200 is opened, and the pressure in the accumulator tank 8 is reduced and adjusted and supplied directly to the air-using equipment 200.

[0045] Next, the operation of supplying high-temperature steam will be described.

[0046] High-temperature steam is generated in a boiler unit 40. In a low-pressure steam generator 43, low-temperature water flowing in from a gas-liquid separator 42 via a water supply pipe is separated into gas and liquid, and the liquid low-temperature water is sent to the heat exchanger 32 by a low-temperature water circulation pump 44.

[0047] The heat storage medium stored in the heat storage tank 21 is supplied to the heat exchanger 32 by the pump 28, where it exchanges heat with low-temperature water flowing in from the low-pressure steam generator 43, heating the low-temperature water. A portion of the heated low-temperature water vaporizes to become low-pressure steam below atmospheric pressure, which undergoes gas-liquid separation and is then sucked into the steam compressor 41. The low-pressure steam is compressed by the steam compressor 41 to a high-temperature, high-pressure state, passes through the gas-liquid separator 42, and is supplied from a steam pipe as a heat source for process heating or the like in a factory or the like.

[0048] The condensed water separated in the gas-liquid separator 42 is used to heat and exchange heat with the water supplied to the low-pressure steam generator 43 in the medium-temperature water heat recovery heat exchanger 47, and then the pressure is reduced to low by the pressure reducing valve 45 and returned to the low-pressure steam generator 43.

[0049] As will be described later, the high-temperature steam generated in the boiler unit 40 is also used for expansion power generation by the expanders 10 and 11. For expansion power generation, valves 55, 56, 57, and 58 that supply high-temperature steam to pipes 94, 95, 96, and 97 connected to the heat exchangers 26 and 27 and the inlets of the expanders 10 and 11 are opened to supply high-temperature steam to the power generation unit 3.

[0050] Next, a power generating operation in which compressed air is used to drive a generator to generate electricity will be described.

[0051] The compressed air stored in the accumulator tank 8 is supplied to the heat exchanger 26 by opening the valve 52 of the pipe 91. In the heat exchanger 26, the compressed air is heated to a high temperature by heat exchange with high-temperature steam supplied from the boiler unit 40, and the high-temperature compressed air is drawn into the expander 10 and undergoes the first stage of adiabatic expansion, thereby driving the expander 10.

[0052] The air adiabatically expanded by the expander 10 is supplied to the heat exchanger 27. In the heat exchanger 27, the compressed air is heated to a high temperature by exchanging heat with high-temperature steam supplied from the boiler unit 40, and the compressed air is then drawn into the expander 11, where it undergoes a second stage of adiabatic expansion. This drives the expander 11. The compressed air adiabatically expanded by the expander 11 is again in a low-temperature, low-pressure state, and is released to the atmosphere from the discharge port of the expander 11.

[0053] By driving the expanders 10 and 11, which perform two-stage expansion, electricity is generated by the generator 12 driven by the expander 10 and the generator 13 driven by the expander 11, and the generated electricity is supplied to grid power 20 via a power conditioner 14.

[0054] The compressed air energy stored as compressed air and heat of compression through the above operations is used to supply compressed air, high-temperature steam, and electricity / power.

[0055] The operating modes of the compressed air energy storage device 100 will now be described.

[0056] In operation mode 1, only compressed air storage is performed. The compressed air energy storage device 100 generates compressed air and stores the compressed air in the pressure storage tank 8 and the heat of compression in the heat storage tank 21.

[0057] In operation mode 2, only compressed air is supplied. The compressed air energy storage device 100 operates to supply compressed air.

[0058] Here, when compressed air close to the operating pressure of the air-using equipment 200 is stored in the accumulator tank 8, the pressure is reduced by the valve 51 of the first air pressure pipe 71 and compressed air is supplied (operation mode 2-1).

[0059] On the other hand, when a pressure sufficiently high relative to the operating pressure of the air-using equipment 200 has been accumulated, the valves 52 and 54 are opened, the pressure is reduced by adiabatic expansion in the expander 10, and compressed air is then supplied through the first air pressure pipe 71 (operation mode 2-2). When adiabatic expansion is performed in the expander 10, electricity is also generated at the same time, so electricity is supplied along with the compressed air.

[0060] Furthermore, by providing a plurality of pressure accumulator tanks 8, it is possible to generate electricity according to the demand for electricity.

[0061] When power supply is required, compressed air and power are supplied simultaneously by adiabatically expanding compressed air stored in an accumulator tank 8 by an expander 10. When the pressure in the accumulator tank 8 approaches the operating pressure of the air-using equipment 200, the supply is switched to another accumulator tank 8 storing high-pressure compressed air, and the supply of compressed air and power is continued.

[0062] When power supply is not required, compressed air is supplied from a pressure accumulator tank 8 storing a pressure close to the working pressure of the air-using equipment 200 through a valve 51, and when the pressure drops below the working pressure of the air-using equipment 200, the pressure is switched to another pressure accumulator tank 8 storing a low pressure, and compressed air is supplied through the valve 51.

[0063] In operation mode 3, compressed air storage and compressed air supply are performed simultaneously. The compressed air energy storage device 100 simultaneously performs a charging operation of generating and storing compressed air and an operation of supplying compressed air.

[0064] The air compressors 6 and 7 operate in a storage mode in which they compress the compressed air to a high pressure, and the compressed air in the accumulator tank 8 is supplied by adiabatic expansion in the expander 10 (operation mode 3-1) or by pressure reduction adjustment in the valve 51 (operation mode 3-2).

[0065] In this case, if multiple accumulator tanks 8 are provided, the accumulator tank used for the compressed air storage operation and the accumulator tank used for the compressed air supply may be different tanks.

[0066] Furthermore, because high-temperature heat storage medium is also stored in the heat storage tank 22 by operating the air compressors 6 and 7, the boiler unit 40 is driven to generate high-temperature steam, and the compressed air to be adiabatically expanded is heated in the heat exchanger 26, or the high-temperature steam is directly mixed with the compressed air to heat the compressed air before sending it to the expander 10, thereby increasing the amount of power generation. When heating in the heat exchanger 26, the valve 56 is opened and the high-temperature steam is supplied to the heat exchanger 26 (operation mode 3-1-1). When directly mixing, the valve 58 is opened and the high-temperature steam is supplied to the expander 10 together with the compressed air (operation mode 3-1-2).

[0067] In operation mode 4, only high-temperature steam is supplied. The compressed air energy storage device 100 operates to supply high-temperature steam.

[0068] At this time, if a high-temperature heat storage medium is stored in the heat storage tank 21, the air compressors 6 and 7 are not operated and the boiler unit 40 is operated.

[0069] In operation mode 5, compressed air storage and high-temperature steam supply are performed simultaneously. When there is a demand for steam in the steam-using equipment 300 and there is a shortage of high-temperature heat storage medium stored in the heat storage tank 21, the air compressors 6 and 7 are operated to exchange the heat of compression with the heat storage medium in the heat exchangers 24 and 25, and the air is supplied to the boiler unit 40. At that time, compressed air is stored in the pressure accumulator tank 8.

[0070] In operation mode 6, compressed air and high-temperature steam are supplied simultaneously. Compressed air is supplied from the pressure accumulator tank 8, and high-temperature steam supplies heat from the heat storage medium in the heat storage tank 21 to the boiler unit 40. High-temperature steam is generated in the steam compressor 41 and supplied through the valve 59.

[0071] Here, when either the compressed air or the heat of compression stored in the pressure accumulator tank 8 or the heat storage tank 21 runs short, the air compressors 6 and 7 are operated to supply compressed air and heat of compression to the pressure accumulator tank 8 and the heat storage tank 21. The supply is adjusted to the amount of compressed air and high-temperature steam used (demand) in the factory, but the same amounts are not necessarily required at the same time. The air compressors 6 and 7 are operated according to the demand for either compressed air or heat of compression, whichever is insufficient, and the surplus is stored in the pressure accumulator tank 8 or the heat storage tank 21 and used for the next supply. In other words, the supply of compressed air and high-temperature steam is leveled by the pressure accumulator tank 8 and the heat storage tank 21.

[0072] In operation mode 7, only power generation is performed. The compressed air energy storage device 100 operates by driving the expanders 10 and 11 with compressed air, and driving the generators 12 and 13 to generate power.

[0073] At the same time, the boiler unit 40 is driven to supply high-temperature steam to the heat exchangers 26 and 27, thereby heating the compressed air and increasing the amount of power generation (operation mode 7-1). Also, high-temperature steam can be directly mixed with the compressed air through valves 57 and 58 for heating (operation mode 7-2).

[0074] Immediately after the start of operation of the expanders 10 and 11, heating is performed by direct mixing, which allows for a faster temperature rise, and once the temperatures of the heat exchangers 26 and 27 have risen sufficiently, heating is switched to using the heat exchangers 26 and 27. That is, immediately after the start of operation, valves 55, 56, 57, and 58 are opened, high-temperature steam is supplied to the heat exchangers 26 and 27, and direct mixing is performed with the compressed air, and after the outlet air temperatures of the heat exchangers 26 and 27 have risen sufficiently, valves 57 and 58 are closed, ending direct mixing.

[0075] It is also possible to operate the system to generate electricity by supplying only compressed air to the expanders 10 and 11 without operating the boiler unit 40 (operation mode 7-3). In this case, the amount of electricity generated is lower than when high-temperature compressed air flows into the expanders 10 and 11.

[0076] In operation mode 8, power generation and compressed air supply are performed simultaneously. The compressed air energy storage device 100 simultaneously performs an operation of generating power by driving a generator with compressed air and an operation of supplying compressed air.

[0077] In this case, there are three operation modes: the first is a mode in which adiabatic expansion power generation is performed by the expander 10 and compressed air is supplied through valves 52 and 54 (operation mode 8-1), the second is a mode in which compressed air is reduced in pressure by valve 51 and supplied, and valves 52 and 53 are also opened to simultaneously perform expansion power generation by the expanders 10 and 11 (operation mode 8-2), and the third is a mode in which the boiler unit 40 is also operated simultaneously to heat the compressed air with high-pressure steam and then perform expansion power generation (operation mode 8-3). These modes switch operation according to the amount of power generation required along with the supply of compressed air, and when more power generation is required, the mode switches from operation mode 8-1 to operation mode 8-2, or from operation mode 8-2 to operation mode 8-3.

[0078] Furthermore, when a plurality of accumulator tanks 8 are used, the accumulator tank 8 used to drive the expander and the accumulator tank 8 used to supply compressed air are separate tanks.

[0079] In operation mode 9, high-temperature steam supply and power generation supply are performed simultaneously. The compressed air energy storage device 100 performs high-temperature steam supply operations and power generation operations simultaneously.

[0080] The boiler unit 40 generates high-temperature steam and supplies the high-temperature steam through a valve 59, and also heats compressed air, thereby heating the compressed air to be drawn into the expanders 10 and 11 at a high temperature.

[0081] At this time, if compressed air is stored in the accumulator tank 8, the valves 52, 53, 55, 56, 57, and 58 are opened, the compressed air in the accumulator tank 8 is heated by the heat exchangers 26 and 27 and the above-mentioned direct mixing, the expanders 10 and 11 are driven, and electricity is generated by the generators 12 and 13 (operation mode 9-1).

[0082] When there is not enough compressed air stored in the accumulator tank 8 for expansion power generation, there are two operating modes: one is a mode in which the air compressors 6 and 7 are operated to supply compressed air (operating mode 9-2-1), and the other is a mode in which the valves 52, 55, and 56 are closed and the expanders 10 and 11 are driven only by high-temperature steam without using compressed air (operating mode 9-2-2). These modes are switched according to the requirements for power supply and demand adjustment, which will be described later.

[0083] The operation mode switching and power supply and demand adjustment of the compressed air energy storage device 100 will be described.

[0084] When a solar power generation device 18 and a wind power generation device 19 are connected to grid power 20 and electricity derived from renewable energy generation is used, if the amount of electricity generated from renewable energy exceeds the amount of electricity used and surplus electricity is generated, the compressed air energy storage device 100 operates in operation mode 1 for storing compressed air, and stores the surplus electricity as compressed air and compression heat.

[0085] In this case, when the demand for compressed air in the air-using equipment 200 is high and the amount of air used is large, the compressed air energy storage device 100 operates in operation mode 3, which simultaneously stores and supplies compressed air. At this time, the air used by the air-using equipment 200 uses the compressed air stored in the accumulator tank 8.

[0086] Furthermore, when the demand for high-temperature steam in the steam-using equipment 300 is high and the amount of steam used is large, the compressed air energy storage device 100 operates in operation mode 5, which simultaneously stores compressed air and supplies high-temperature steam. At this time, the high-temperature steam used in the steam-using equipment 300 has the compression heat stored in the heat storage tank 21 recovered by the boiler unit 40, and high-temperature steam is generated by the steam compressor 41.

[0087] When there is no request to operate the air pressure using equipment 200 and the steam using equipment 300, for example when production equipment in the factory is stopped, the equipment is operated in operation mode 1 in which only compressed air is stored.

[0088] The stored compressed air and heat of compression are also used as a heat source for supplying compressed air and generating high-temperature steam, so it is desirable to store a sufficient amount of compressed air during times when electricity demand is low.

[0089] In cases where the amount of renewable energy generated during the day is large and surplus power is generated, operating in charging mode at night can level out power usage during the day and night, and can also reduce power costs by reducing grid power usage at night. Next, when the amount of renewable energy generated is less than the amount of power used, the compressed air energy storage device 100 operates in operation mode 6, which supplies compressed air and high-temperature steam. Compressed air from the storage tank 8 is supplied to the air-using equipment 200, the compression heat stored in the heat storage tank 21 is recovered by the boiler unit 40, high-temperature steam is generated by the steam compressor 41 and supplied to the steam-using equipment 300, and the operation of the air compressors 6 and 7 is stopped.

[0090] Since no electricity is required to produce compressed air, power demand can be reduced by 10 to 20% of the factory's electricity consumption. In addition, the energy used to generate high-temperature steam is used to operate the steam compressor 41, reducing the use of fossil fuels such as kerosene and gas in combustion boilers and significantly reducing carbon dioxide emissions.

[0091] Furthermore, when the amount of renewable energy power generation is low and there is no operation request from the air-using equipment 200, the supply of compressed air from the accumulator tank 8 is stopped, and the compressed air from the accumulator tank 8 is used to drive the expanders 10 and 11, generating power using the expanders. At this time, if there is an operation request from the steam-using equipment 300 and the boiler unit 40 is operating, it is operated in operation mode 9-1. However, high-pressure steam is supplied preferentially to the steam-using equipment 300, and is not supplied to the heat exchangers 26 and 27, and a small amount is heated by directly mixing it with the compressed air through valves 57 and 58, or only expansion power generation is performed without heating the air.

[0092] When the amount of compressed air in the accumulator tank 8 becomes low, the operation mode is switched to 9-2-2. When there is a surplus in the amount of steam generated in the boiler unit 40 compared to the amount of high-temperature steam supplied to the steam-using equipment 300, power generation can be performed using only high-temperature steam, while also reducing power consumption by reducing power demand. When there is not a surplus in the amount of steam generated in the boiler unit 40, priority is given to the supply of high-temperature steam to the steam-using equipment 300, and power generation is stopped.

[0093] Furthermore, when there is no operation request from the steam-using equipment 300, the system operates in operation mode 7, and high-temperature steam is not supplied to the steam-using equipment 300 but is used to heat the compressed air. This makes it possible to make up for any shortfall in power generation through expansion power generation, thereby reducing the demand for grid power. When there is no operation request from the steam-using equipment 300, the system switches to operation mode 7-3, stops operation of the boiler unit 40, and performs expansion power generation without heating the compressed air, thereby making it possible to further reduce the amount of power used.

[0094] The operation control process executed by the control device 80 of the compressed air energy storage device 100 will be described.

[0095] FIG. 7 is a flowchart of an operation control process executed by the control device 80 of the compressed air energy storage device 100 of the first embodiment.

[0096] The control device 80 determines whether there is a demand for compressed air from the air pressure using equipment 200 (step S101). If there is no demand for compressed air from the air pressure using equipment 200 in step S101, the process proceeds to step S107.

[0097] On the other hand, if there is a demand for compressed air from the air-using equipment 200 in step S101, it is determined whether compressed air is stored in the accumulator tank 8 (step S102). If compressed air is not stored in the accumulator tank 8 in step S102, the control device 80 operates the air compressors 6 and 7 to generate compressed air and compression heat, stores the generated compressed air and compression heat in the accumulator tank 8 and heat storage tank 21 (step S103), controls the valve 51 to reduce the pressure of the compressed air, and supplies the compressed air to the air-using equipment 200 (step S104), and then proceeds to step S107.

[0098] On the other hand, if compressed air is stored in the accumulator tank 8 in step S102, it is determined whether the pressure of the compressed air stored in the accumulator tank 8 is higher than the operating pressure of the air-using equipment 200 (step S105). If the pressure of the compressed air stored in the accumulator tank 8 is approximately the same as the operating pressure of the air-using equipment 200 (NO in step S105), the process proceeds to step S104, where the valve 51 is controlled to reduce the pressure of the compressed air and supply the compressed air to the air-using equipment 200.

[0099] On the other hand, if the pressure of the compressed air stored in the accumulator tank 8 in step S105 is higher than the operating pressure of the air-using equipment 200, the valves 52 and 54 are opened, the compressed air is reduced in pressure by adiabatic expansion in the expander 10, and then the compressed air is supplied through the first air pressure piping 71 (step S106), and the process proceeds to step S107.

[0100] In step S107, the control device 80 determines whether or not there is a demand for high-temperature steam from the steam-using equipment 300. If there is no demand for high-temperature steam from the steam-using equipment 300 in step S107, the process proceeds to step S111.

[0101] On the other hand, if there is a demand for high-temperature steam from the steam-using equipment 300 in step S107, it is determined whether or not heat of compression has been stored in the heat storage tank 21 (step S108). If heat of compression has not been stored in the heat storage tank 21 in step S108, the control device 80 operates the air compressors 6 and 7 to generate compressed air and heat of compression, and stores the generated compressed air and heat of compression in the pressure storage tank 8 and the heat storage tank 21 (step S109).

[0102] Next, the control device 80 operates the steam compressor 41 to generate high-temperature steam, controls the valve 59 to supply the high-temperature steam to the steam-using equipment 300 (step S110), and proceeds to step S111.

[0103] On the other hand, if the heat of compression has been stored in the heat storage tank 21 in step S108, the control device 80 skips step S109 and proceeds to step S110.

[0104] In step S111, the control device 80 determines whether or not the power usage in the factory is high and there is a demand for power. If there is no demand for power in step S111, the process proceeds to step S118.

[0105] On the other hand, if there is a demand for electricity in step S111, it is determined whether compressed air is stored in the accumulator tank 8 (step S112). If compressed air is stored in the accumulator tank 8 in step S110, the control device 80 determines whether the steam compressor 41 is operating (step S113).

[0106] If the steam compressor 41 is operating in step S113, the control device 80 opens valves 52, 53, and 54 to send compressed air from the accumulator tank 8 to the expanders 10 and 11, opens valves 55 and 56 or valves 57 and 58 to heat the compressed air with high-pressure steam, and drives the generators 12 and 13 with the expanders 10 and 11 to generate electricity (step S114), and then proceeds to step S118.

[0107] If the steam compressor 41 is not operating in step S113, the control device 80 opens the valves 52, 53, and 54 to send compressed air from the accumulator tank 8 to the expanders 10 and 11, and supplies only compressed air to the expanders 10 and 11 to generate electricity (step S115), and then proceeds to step S118.

[0108] If it is determined in step S116 that compressed air is not stored in the accumulator tank 8, the control device 80 determines whether the steam compressor 41 is operating (step S116).

[0109] If the steam compressor 41 is operating in step S116, the control device 80 opens valves 57 and 58 to send high-pressure steam to the expanders 10 and 11, and supplies only high-temperature steam to the expanders 10 and 11 to generate electricity (step S117), and then proceeds to step S118.

[0110] If it is determined in step S116 that the steam compressor 41 is not operating, the process proceeds to step S118 without generating electricity.

[0111] In step S118, the control device 80 determines whether the amount of power generated by renewable energy exceeds the amount of power used, resulting in the generation of surplus power.

[0112] If surplus electricity is generated in step S118, the control device 80 operates the air compressors 6 and 7 to generate compressed air and compressed heat, stores the generated compressed air and compressed heat in the pressure storage tank 8 and the heat storage tank 21 (step S119), and terminates the processing.

[0113] On the other hand, if surplus power is not generated in step S118, the control device 80 ends the process.

[0114] As described above, in this embodiment, the compressed air and heat of compression generated by the air compressors 6, 7 are stored in the pressure storage tank 8 and the heat storage tank 21, the compressed air is used both to supply compressed air and to generate electricity by driving the expanders 10, 11 and the generators 12, 13 directly connected thereto, and the heat of compression is used both to supply high-temperature steam and to heat the expander inlet air to drive the generators.Furthermore, the pressure storage tank 8 and the heat storage tank 21 make it possible to shift the time from generation to use, which makes it possible to adjust the supply and demand of electricity within the factory, and it is possible to provide a compressed air energy storage device that integrates an air compressor and a steam boiler, which makes it possible to use renewable energy as the main power source and reduce grid power consumption.

[0115] 2 is a diagram showing an example of a schematic configuration of a compressed air energy storage device according to Example 2. In the following, the same components as those in Example 1 are denoted by the same reference numerals, and redundant explanations will be omitted.

[0116] In the second embodiment, the heat storage medium flow circuit that connects the heat storage tank 21 to the heat exchanger 32 branches off midway and has heat storage medium flow circuits that connect to the heat exchangers 34 and 35. The fluid circuits that connect to the heat exchangers 34 and 35 can be opened and closed by valves 61, 62, 63, and 64, respectively. These fluid circuits are provided with pumps 28 and 29 for transporting the heat storage medium.

[0117] Next, a power generating operation in which compressed air is used to drive a generator to generate electricity will be described.

[0118] The compressed air stored in the accumulator tank 8 is supplied to the heat exchangers 34 and 35 by opening the valve 52. In the heat storage unit 2, the high-temperature heat storage medium in the heat storage tank 21 is supplied to the heat exchangers 34 and 35 by opening the valves 61, 63, and 64, and the compressed air is heated to the temperature of the heat storage medium. The compressed air heated in the heat exchanger 35 passes through the heat exchanger 26 and is then supplied to the expander 10 to drive the expander 10.

[0119] The first stage expansion operation is performed in the expander 10, and the discharged compressed air is decompressed and expanded, passed through the valve 53 and supplied to the heat exchanger 34, where it is heated again to the heat storage medium temperature, and then passed through the heat exchanger 27 and sucked into the expander 11, driving the expander 11.

[0120] The expander 11 performs a second-stage expansion operation, and then the refrigerated gas is released into the atmosphere. The expanders 10 and 11 are directly connected to generators 12 and 13, respectively, which generate electricity. The generated electricity is voltage-converted by a power conditioner 14 and supplied to the grid power 20.

[0121] On the other hand, when the valves 61, 63, and 64 are closed and the valve 62 is opened, the heat storage medium flows into the heat exchanger 32 and heats the low-pressure steam in the heat exchanger 32. In this case, the stored heat is used as a heat source for the high-temperature steam generated in the boiler unit 40.

[0122] The compressed air is heated to a high temperature by heat exchange with high-temperature steam supplied from the boiler unit 40, and the compressed air is drawn into the expander 10 where it undergoes the first stage of adiabatic expansion, thereby driving the expander 10.

[0123] The air adiabatically expanded by the expander 10 is supplied to the heat exchanger 27. The compressed air is heated to a high temperature by exchanging heat with high-temperature steam supplied from the boiler unit 40, and the compressed air is then drawn into the expander 11, where it undergoes a second stage of adiabatic expansion. This drives the expander 11. The air adiabatically expanded by the expander 11 is again in a low-temperature, low-pressure state, and is released to the atmosphere from the discharge port of the expander 11.

[0124] By driving the expanders 10 and 11, which perform two-stage expansion, electricity is generated by the generator 12 driven by the expander 10 and the generator 13 driven by the expander 11, and the electricity is supplied to the grid power 20 via the power conditioner 14.

[0125] The operation mode switching and power supply and demand adjustment of the compressed air energy storage device 100 will be described.

[0126] When the amount of renewable energy power generation is less than the amount of power used and there is no operation request from the air pressure using equipment 200 or the steam using equipment 300, the system is operated in operation mode 7. When operation is performed in operation mode 7-3 to reduce the amount of power used, the operation of the boiler unit 40 is stopped and compressed air heating using the heat exchangers 26, 27 is not performed.

[0127] Therefore, in order to prevent the temperature of the compressed air taken into the expanders 10 and 11 from being low and reducing the amount of power generation, the valves 61, 63, and 64 are opened to heat the compressed air using the heat storage medium. This allows the temperature of the compressed air at the expander inlet to be restored to the temperature of the heat storage medium, preventing a reduction in the amount of power generation.

[0128] As described above, in this embodiment, the heat of compression stored in the heat storage tank 21 can be used for both heating compressed air for power generation and supplying high-temperature steam, thereby preventing a decrease in power generation during power supply and demand adjustments and providing a compressed air energy storage device that can achieve high system efficiency.

[0129] 3 is a diagram showing an example of a schematic configuration of a compressed air energy storage device according to Example 3. In the following, the same components as those in Examples 1 and 2 are denoted by the same reference numerals, and redundant explanations will be omitted.

[0130] In the third embodiment, the low-temperature water separated in the low-pressure steam generator 43 is sent to a radiator 49 by a low-temperature water circulation pump 44. The radiator 49 forms a refrigeration cycle together with a compressor 48, a heat absorber 46, a heat exchanger 32, and an expansion valve 50, and the low-temperature water is heated in the radiator 49 by the refrigerant compressed by the compressor 48.

[0131] In the refrigeration cycle, after passing through the radiator 49, the refrigerant is decompressed by the expansion valve 50, and then the refrigerant absorbs heat in the heat absorber 46 and the heat exchanger 32, and returns to the compressor 48. The heat absorber 46 exchanges heat with waste heat from hot water in the factory and recovers waste heat from other equipment, and the heat exchanger 32 exchanges heat between the heat storage medium and the refrigerant in the refrigeration cycle. Carbon dioxide, hydrocarbons, fluorocarbon-based refrigerants, etc. are used as the refrigerant.

[0132] The steam compressor 41 sucks low-pressure steam from the low-pressure steam generator 43, compresses it to high-temperature and high-pressure steam, and supplies it as high-temperature steam as a heat source for process heating in factories and the like.

[0133] Next, the operation of supplying high-temperature steam will be described.

[0134] High-temperature steam is generated in a boiler unit 40. In a low-pressure steam generator 43, low-temperature water flowing in from a gas-liquid separator 42 via a water supply pipe is separated into gas and liquid, and the liquid low-temperature water is sent to a radiator 49 by a low-temperature water circulation pump 44.

[0135] In the radiator 49, the refrigerant that has absorbed heat from the heat absorber 46 and the heat exchanger 32 exchanges heat with the low-temperature water flowing in from the low-pressure steam generator 43, heating the low-temperature water. Part of the heated low-temperature water vaporizes to become low-pressure steam below atmospheric pressure, which undergoes gas-liquid separation and is then sucked into the steam compressor 41. The low-pressure steam is compressed by the steam compressor 41 to a high-temperature, high-pressure state, and passes through the gas-liquid separator 42 to be supplied from a steam pipe as a heat source for process heating in a factory or the like.

[0136] The condensed water separated in the gas-liquid separator 42 is used to heat and exchange heat with the water supplied to the low-pressure steam generator 43 in the medium-temperature water heat recovery heat exchanger 47, and then the pressure is reduced to low by the pressure reducing valve 45 and the water is returned to the low-pressure steam generator 43.

[0137] The high-temperature steam generated in the boiler unit 40 is also used for expansion power generation by the expander. For expansion power generation, the valves supplying the high-temperature steam to the suction pipes of the heat exchangers 26 and 27 and the expanders 10 and 11 are opened to supply the high-temperature steam to the power generation unit 3.

[0138] The operation mode switching and power supply and demand adjustment of the compressed air energy storage device 100 will be described.

[0139] When the amount of renewable energy power generation is less than the amount of power used, there is no operation request from the air pressure using equipment 200, and there is an operation request from the steam using equipment 300, the system operates in operation mode 9-1. High-pressure steam is supplied to the steam using equipment 300 with priority, and is supplied to the heat exchangers 26 and 27 only when there is a surplus in the high-temperature steam supply.

[0140] In addition, since the boiler unit 40 uses the heat storage medium stored in the heat storage tank 21 as well as the hot water exhaust heat outside the system as a heat source, the capacity of the boiler unit 40 can be increased, and high-temperature steam supply and compressed air heating can be performed simultaneously.

[0141] As described above, in this embodiment, in addition to the heat of compression stored in the heat storage tank 21, other exhaust heat can be used as a heat source when supplying high-temperature steam, so it is possible to provide a compressed air energy storage device that can increase the amount of power generated when adjusting power supply and demand and achieve high system efficiency.

[0142] 4 is a diagram showing an example of a schematic configuration of a compressed air energy storage device according to Example 4. In the following, the same components as those in Examples 1 to 3 are denoted by the same reference numerals, and redundant explanations will be omitted.

[0143] In the fourth embodiment, the refrigeration cycle of the boiler unit 40 decompresses the refrigerant after passing through the radiator 49 in the expansion valve 50, and then absorbs heat in the heat exchanger 32 and the heat absorber 46, returning to the compressor 48. The heat exchanger 32 exchanges heat between the heat storage medium and the refrigerant in the refrigeration cycle, and the heat absorber 46 exchanges heat with waste heat such as waste heat from hot water in the factory, recovering waste heat from other equipment. Carbon dioxide, hydrocarbons, fluorocarbon-based refrigerants, etc. are used as the refrigerant.

[0144] The difference from the third embodiment is the order of the heat absorber 46 and the heat exchanger 32 in the refrigeration cycle. In the third embodiment, the heat exchanger 32 is arranged downstream of the heat absorber 46, but in this embodiment, the heat absorber 46 is arranged downstream of the heat exchanger 32.

[0145] As described above, in this embodiment, the heat absorber 46 is arranged downstream of the heat exchanger 32, so that even if the temperature of the heat storage medium after heat exchange in the heat exchangers 34 and 35 is lower than the hot water exhaust heat temperature, heat can be effectively absorbed, and the supply capacity of high-temperature steam can be increased.

[0146] 5 is a diagram showing an example of a schematic configuration of a compressed air energy storage device according to Example 5. In the following, the same components as those in Examples 1 to 4 are denoted by the same reference numerals, and redundant explanations will be omitted.

[0147] In the fifth embodiment, the refrigeration cycle of the boiler unit 40 is composed of a compressor 48 , a radiator 49 , an expansion valve 50 , and a heat absorber 46 .

[0148] Both the heat absorber 46 and the heat exchanger 32 use hot water and exchange heat between the refrigerant and the heat storage medium. Waste heat from the hot water from other equipment is supplied to the heat exchanger 32 and the heat absorber 46, where it is absorbed in the heat exchanger 32 from the heat storage medium that has undergone heat exchange in the heat exchangers 26 and 27, and then dissipated to the refrigerant in the heat absorber 46. Carbon dioxide, hydrocarbons, fluorocarbon-based refrigerants, etc., are used as the refrigerant.

[0149] The order in which the hot water is supplied to the heat absorber 46 and the heat exchanger 32 can be changed. In FIG. 5, the hot water is circulated through the heat absorber 46 and then the heat exchanger 32, but the direction of circulation may be changed depending on the temperatures of the waste heat hot water from other devices and the low-temperature heat storage medium.

[0150] As described above, in this embodiment, by changing the direction of hot water circulation while maintaining the same configuration, it is possible to accommodate the temperature difference between the waste heat hot water and the low-temperature heat storage medium, thereby enabling efficient steam generation.

[0151] 6 is a diagram showing an example of a schematic configuration of a compressed air energy storage device according to Example 6. In the following, the same components as those in Examples 1 to 5 are denoted by the same reference numerals, and redundant explanations will be omitted.

[0152] In the sixth embodiment, the refrigeration cycle of the boiler unit 40 is formed by a radiator 49, a compressor 48, a heat absorber 46, and an expansion valve 50. The heat absorber 46 absorbs heat from the atmosphere, and the radiator 49 heats low-temperature water with the refrigerant compressed by the compressor 48. Carbon dioxide, hydrocarbons, fluorocarbon-based refrigerants, etc. are used as the refrigerant.

[0153] The steam compressor 41 sucks low-pressure steam from the low-pressure steam generator 43, compresses it to high-temperature and high-pressure steam, and supplies it as high-temperature steam as a heat source for process heating or the like in a factory or the like.

[0154] As described above, in this embodiment, the heat of compression stored in the heat storage tank 21 is used only to heat the compressed air during power generation, and heat is pumped from the atmosphere and used as a heat source for supplying high-temperature steam. It is possible to provide a compressed air energy storage device that can supply compressed air, high-temperature steam, and electricity by utilizing heat other than the heat of compression and the hot water exhaust heat of other equipment.

[0155] In each of the above embodiments, the renewable energy power generation device can be any device that utilizes energy that is constantly (or repeatedly) replenished by natural forces and that fluctuates irregularly, such as wind power, sunlight, solar heat, wave or tidal power, flowing water or tides, and geothermal heat. The compressed air energy storage device of each embodiment can also be applied to cases where the power demand of a factory fluctuates significantly depending on the operating state of large-power-consuming equipment within the factory. The power transmission and distribution system is not limited to a general power company power transmission and distribution system, but may also be a local or factory microgrid power system.

[0156] In addition, although the air compressors 6, 7 and the expanders 10, 11 in each embodiment may be, for example, screw types, the types of these rotary machines are not limited thereto. The air compressors 6, 7 and the expanders 10, 11 may be, for example, scroll types, turbo types, or reciprocating types.

[0157] In addition, in each embodiment, the air compressors 6 and 7 and the expanders 10 and 11 are each a two-stage compression / two-stage expansion type, but the air compressors and expanders may be a single-stage compression / single-stage expansion type, or a three- or more-stage compression / expansion type, or the number of stages may be different for compression and expansion. Furthermore, the compressed air energy storage device may be provided with multiple air compressors and expanders. Also, there may be configurations where the number of motors and compressors differs (for example, when one motor drives multiple compressors), or where the number of generators and expanders differs (for example, when multiple expanders drive one generator).

[0158] 1 Air pressure unit 2 Heat storage unit 3 Power generation unit 4, 5 Motor 6, 7 Air compressor 8 Pressure storage tank 9 Inverter 10, 11 Expansion machine 12, 13 Generator 14 Power conditioner 18 Photovoltaic power generation device 19 Wind power generation device 20 Grid power 21 High temperature side heat storage tank 22 Low temperature side heat storage tank 24, 25 Heat exchanger 26, 27 Heat exchanger 28, 29 Pump 32 Heat exchanger 34, 35 Heat exchanger 40 Boiler unit 41 Steam compressor 42 Gas-liquid separator 43 Low pressure steam generator 44 Low temperature water circulation pump 45 Pressure reducing valve 46 Heat absorber 47 Medium temperature water heat recovery heat exchanger 48 Compressor 49 Radiator 50 Expansion valve 51 to 64 Valve 71 First air pressure pipe 72 First steam pipe 100 Compressed air energy storage device

Claims

1. A compressed air energy storage device comprising: an air compressor that generates compressed air; a first heat exchanger that exchanges heat between the compressed air and a heat storage medium; a pressure storage tank that stores the compressed air that has been heat exchanged in the first heat exchanger; a heat storage tank that stores the heat storage medium that has been heat exchanged in the first heat exchanger; a low-pressure steam generating device that heats water by heat exchange with the heat storage medium to generate low-pressure steam; a steam compressor that compresses the low-pressure steam to generate high-temperature steam; a generator that generates electricity; and an expander that drives the generator with the compressed air or the high-temperature steam, and which supplies one or more of the compressed air, the high-temperature steam, and the electricity.

2. A compressed air energy storage device as defined in claim 1, further comprising a plurality of valves for opening and closing pipes through which the compressed air or the high-temperature steam passes, and a control device for controlling the operation of the air compressor, the operation of the steam compressor, and the opening and closing of each of the plurality of valves in accordance with demand for the compressed air, the high-temperature steam, and the electricity.

3. A compressed air energy storage device as claimed in claim 2, further comprising a heating means for heating the compressed air with the high-temperature steam or the heat storage medium, and the expander drives the generator with the compressed air heated by the heating means.

4. A compressed air energy storage device according to claim 3, wherein the heating means heats the compressed air by heat exchange with the high-temperature steam.

5. A compressed air energy storage device according to claim 3, wherein the heating means heats the compressed air by mixing the compressed air with high-temperature steam.

6. A compressed air energy storage device according to claim 3, wherein the heating means heats the compressed air by heat exchange with the heat storage medium.

7. A compressed air energy storage system according to claim 2, wherein the low pressure steam generating device generates the low pressure steam by heating the water through heat exchange with the heat storage medium.

8. A compressed air energy storage device as claimed in claim 2, further comprising: a refrigerant compressor which compresses and heats a refrigerant; and an expansion valve which reduces the pressure of the refrigerant, wherein the low-pressure steam generating device generates the low-pressure steam by heating the water through heat exchange with the refrigerant.

9. A compressed air energy storage device according to claim 8, further comprising a second heat exchanger for heating the refrigerant by heat exchange with the heat storage medium.

10. A compressed air energy storage device according to claim 8, further comprising a heat sink for heating the refrigerant by heat exchange with hot water from another device.

11. A compressed air energy storage device according to claim 10, further comprising a third heat exchanger for heating the hot water from the other equipment by heat exchange with the heat storage medium.

12. A compressed air energy storage system according to claim 8, further comprising a second heat sink for heating the refrigerant by heat exchange with the atmosphere.

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