System and method for energy storage and recovery with start-up assistance for compression means

Abstract

The invention relates to a compressed gas energy storage and recovery system comprising: - a compression line (1) with at least one compression stage (3), each comprising a compression means (100, 101, 102) and at least two heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) in parallel, - at least two compressed gas storage means (1000A, 1000B) in parallel, - an expansion line (2) comprising at least one expansion stage (4) and conduits for circulating the compressed gas in the heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B). Furthermore, the energy storage and recovery system includes at least one mechanical connection / disconnection means (C) for connecting / disconnecting at least one compression means (100, 101, 102) of a compression stage to at least one expansion means (700, 701, 702) of an expansion stage. Figure 2 to be published

Description

Title of the invention: System and method for storing and recovering energy with assistance in starting compression means Technical field

[0001] The present invention relates to the technical field of energy storage and recovery by compressed gas, in particular compressed air.

[0002] While global energy objectives aim to promote renewable energies in order to progressively increase their share in the energy mix, the variable nature of these renewable energies remains their major drawback. To address this issue, energy storage appears to be a very advantageous solution. By storing surplus energy produced at peak production so that it can be used when production falls below demand, storage overcomes the constraint of variability and provides flexibility, or even continuity, for renewable energies. Thus, the need for energy storage processes and systems is expected to increase in the coming years, along with the proportion of renewable energies in the global energy mix.

[0003] Numerous storage technologies currently exist, such as mechanical storage systems like Pumped Storage Hydroelectric Power Plants (PSHPs), which use hydroelectricity produced by two water reservoirs located at different altitudes. During the electricity storage phase, water from the lower reservoir is pumped to the upper reservoir and stored at that altitude. When electricity demand increases, water from the upper reservoir is returned to the lower reservoir via a hydraulic turbine, which then generates electricity through a generator. Hydroelectric dams also operate on the same principle: the dam retains water at a higher altitude upstream than downstream, and when electricity demand increases, the dam releases the water, allowing it to pass through hydraulic turbine-generators that produce electricity.

[0004] Electrochemical technologies can also be used for energy storage such as lithium-ion, lead-acid or nickel-cadmium batteries, or circulation batteries.

[0005] Compressed air energy storage and recovery, known as CAES (Compressed Air Energy Storage), is a technology for which the first installation, with a capacity of 290 MW, was built in Germany in the late 1970s. The principle of this technology is to use electricity produced but not consumed to compress a gas, typically air. In order to To prevent damage to the compressors, the heat generated during compression is dissipated between each stage. The compressed air, at medium to high pressure (40 bar to 300 bar, or 4 to 30 MPa), is sent to a natural storage site such as a salt cavern, a mine (salt, limestone, coal), or an artificial storage site while awaiting the energy discharge phase. During the electricity generation phase, the stored air is extracted from the storage site and expanded in turbogenerators.

[0006] A variant of CAES technology is the adiabatic process, also called AACAES (Advanced Adiabatic Compressed Air Energy Storage). The main difference with CAES is that the heat resulting from compression is no longer simply dissipated between each stage, i.e., lost, but stored in order to preheat the air upstream of the turbines during the energy recovery phase. Thanks to this reuse of the internal thermal energy of the process, the efficiency of AACAES can reach approximately 70% instead of approximately 50% for the CAES process. The air is cooled during the compression phase in a heat exchanger with a heat transfer fluid. The hot heat transfer fluid is then stored so that it can release its heat to the air during the expansion phase. Previous technique

[0007] French patent application FR 3117165 Al (WO2022 / 117398) relates to an AACAES system.

[0008] Figure 1 schematically illustrates, in block diagram form, such a system and method. This figure shows the energy storage phase by gas compression and the energy production phase by gas expansion. The prior art system consists of a compression line (1), including one or more compression stages (3) depending on the air pressure to be achieved and the suppliers' recommendations. In the illustrated embodiment, the compression line (1) comprises three compression stages (3). Each compression stage (3) includes a compression means (100, 101, 102), also called a compressor. Compressor (100) is a low-pressure compressor, compressor (101) is a medium-pressure compressor, and compressor (102) is a high-pressure compressor.The gas used (10) in the illustrated process is ambient air, containing a water saturation related to its temperature and pressure. During the energy storage phase, the air is compressed in the compression line (1) and then sent to a compressed air storage unit (1000) adapted to high pressures. Heat storage and recovery units (200, 201, 202) are arranged after each compressor (100, 101, 102) of each compression stage (3) in order to cool the hot compressed air exiting the compression stage while simultaneously... storing this thermal energy. The heat storage and recovery unit (200) is suitable for low pressure, the heat storage and recovery unit (201) is suitable for medium pressure, and the heat storage and recovery unit (202) is suitable for high pressure. Cooling units (300, 301, 302) can be arranged downstream of the heat storage and recovery units (200, 201, 202) if necessary to complete the cooling of the compressed air before the next compression stage or before its storage. Once the air has been cooled and before the next compression stage, the condensed water, resulting from the humidity in the air, is extracted from the compressed air stream by gas-liquid separators (400, 401, 402) to ensure that the air inlet to the compressor is free of any trace of liquid water.This water condensation can occur in the heat storage and recovery units (200, 201, 202) and / or in the cooling units (300, 301, 302). During the power generation phase, the compressed air is expanded via one or more turbines (700, 701, 702) or expansion stage, according to the suppliers' recommendations, in order to generate electricity via alternators, which are not shown in the diagram. Turbine (702) is a low-pressure turbine, turbine (701) is a medium-pressure turbine, and turbine (700) is a high-pressure turbine.

[0009] AACAES systems are designed for high power outputs on the order of several megawatts. Therefore, the compressors must be powered by electric motors of several megawatts. Starting electric motors of this power is difficult. To do this, an electronic soft starter or a variable frequency drive (VFD) starter is generally used. In both cases, a significant delay (at least half an hour) is required to reach the compressor's nominal operating point. Furthermore, an investment in dedicated starting equipment is also necessary. Thus, starting the compressors results in high energy consumption and starting difficulties. Summary of the invention

[0010] The object of the invention is to facilitate the starting of compressors, by accelerating the start-up, and to limit the energy consumption of the start-up.

[0011] The invention relates to a compressed gas energy storage and recovery system comprising:

[0012] - a gas compression line with at least one compression stage, each compression stage comprising a compression means and at least two means for storing and recovering heat downstream, in the direction of gas flow, of said compression means, the at least two means for storing and recovering heat sources being connected in parallel,

[0013] - at least two compressed gas storage means located at the outlet of the line gas compression for storing compressed gas, said at least two compressed gas storage means being connected in parallel,

[0014] - a pressure-reducing line for releasing compressed gas stored in the means of compressed gas storage, the expansion line comprising at least one expansion stage, each expansion stage comprising piping and an expansion means, the piping being configured to circulate the compressed gas through said at least two means of storage and heat recovery from the same compression stage so as to heat the compressed gas before the expansion means.

[0015] Furthermore, the energy storage and recovery system includes at least one mechanical connection / disconnection means for connecting / disconnecting at least one compression means of a compression stage to at least one expansion means of an expansion stage, preferably to a single expansion means of an expansion stage.

[0016] Preferably, the system comprises as many compression stages as expansion stages.

[0017] Advantageously, each compression stage of the compression line is defined by a passage number (or passage order), the passage number corresponding to the passage order of the compressed gas in that compression stage within the compression line, for which each expansion stage of the expansion line is defined by an output number, the output number corresponding to the order of that expansion stage within the expansion line, in the reverse direction of the passage of the compressed gas in the expansion line and for which each connection / disconnection means is configured to connect / disconnect the compression means of the compression stage of the defined passage number by means of the expansion stage of the defined output number, the defined passage number being equal to the output number.

[0018] Preferably, the compression line comprises three compression stages and the expansion line comprises three expansion stages.

[0019] Advantageously, the system includes a first connection / disconnection means for the connection between the compression means of the last compression stage and the expansion means of the first expansion stage, a second connection / disconnection means for the connection between the compression means of the intermediate compression stage and the expansion means of the intermediate expansion stage, and a third connection / disconnection means for the connection between the compression means of the first compression stage and the expansion means of the last expansion stage.

[0020] According to one embodiment of the invention, at least one means of connection / disconnection includes a shaft for mechanically connecting at least one compression means to at least one expansion means.

[0021] Preferably, at least one means of connection / disconnection includes a clutch.

[0022] According to one configuration of the invention, each compression stage includes a cooling means downstream of said at least two means for storing and recovering heat and preferably a gas / liquid separation means, downstream of the cooling means.

[0023] Advantageously, at least one expansion means, preferably each expansion means, is connected to an electrical machine capable of generating electricity in the expansion phase and capable of participating in the starting of the compression means at the start of the compression phase.

[0024] According to a variant of the invention, first valves and / or second valves are positioned upstream and / or downstream of each heat storage and recovery means.

[0025] Preferably, first and second opening / closing means are positioned upstream and / or downstream of each compressed gas storage means.

[0026] The invention also relates to a compressed gas energy storage and recovery method, in which a compressed gas energy storage and recovery system is used according to one of the variants or combinations of variants described above, and in which at least the following steps are carried out: - During the expansion phase, the compressed gas is expanded from said at least two compressed gas storage means and the expansion phase is stopped when the compressed gas pressure in at least one of said at least two compressed gas storage means reaches a predetermined pressure and / or when the outlet temperature of at least one of the heat storage and recovery means reaches a predefined temperature; - At the start of the compression phase, the remaining compressed gas in at least one of the at least two compressed gas storage means is transferred to the expansion line and, in each expansion stage, the remaining heat from the said storage and heat recovery means is recovered before passing the compressed gas into the expansion means, the expansion means then being mechanically connected to a compression means of a compression stage, via a connection / disconnection means; Then, when the compression phase has started and once the compressed gas is completely discharged from said at least two compressed gas storage means, the disconnection of each connection / disconnection means is activated so as to mechanically disconnect the compression means from the associated expansion means and the The compression devices are then driven by an electric motor.

[0027] Advantageously, before mechanically activating the disconnection of each connection / disconnection means, the heat contained in the heat storage and recovery means is discharged.

[0028] Preferably, when starting the compression phase, alternatively or additionally to the use of compressed gas exiting the compressed gas storage means, each electrical machine connected to the expansion means is used to participate in starting the compression means. List of figures

[0029] Other features and advantages of the device and / or system according to the invention will become apparent from the following description of non-limiting examples of embodiments, with reference to the figures attached and described below. [Fig 1]

[0030] Fig. 1 (already described) represents a compressed gas energy storage and recovery system according to the prior art. [Fig 2]

[0031] Figure [Fig.2] represents a compressed gas energy storage and recovery system according to the invention. [Fig 3]

[0032] Fig. 3 represents the compressed gas energy storage and recovery system according to the invention of Fig. 2 in the start-up phase of the compression means. Description of the implementation methods

[0033] The invention relates to a compressed gas energy storage and recovery system (in particular, air, and more particularly air taken from the ambient environment) comprising:

[0034] - a gas compression line with at least one compression stage, each compression stage comprising a compression means and at least two means for storing and recovering heat downstream, in the direction of gas flow, of said compression means, the at least two means for storing and recovering heat being mounted in parallel;

[0035] - at least two compressed gas storage means located at the outlet of the line gas compression for storing compressed gas, said at least two means of compressed gas storage being mounted in parallel;

[0036] - a pressure-reducing line for releasing compressed gas stored in the means of compressed gas storage, the expansion line comprising at least one expansion stage, each expansion stage comprising piping and an expansion means, the pipes being configured to circulate the compressed gas in said at least two means of heat storage and recovery of the same compression stage so as to heat the compressed gas before the expansion means.

[0037] Thus, the compression line allows gas to be compressed when electricity production exceeds demand; the compressed gas can then be used to supply electricity when electricity demand is high. The compression line therefore allows energy to be stored by means of compressed gas (particularly compressed air, the air being advantageously drawn from the ambient environment).

[0038] The expansion line allows the stored compressed gas to be transformed into mechanical energy, for example rotary energy, by means of the expansion means (a turbine, for example) of each expansion stage. Advantageously, the expansion means can be coupled to a generator (also called an alternator) to transform the mechanical energy into electricity.

[0039] In the compression line as in the expansion line, the different stages (compression or expansion respectively) are successive, that is to say they are positioned in series, one after the other in the direction of gas flow in the compression or expansion line respectively.

[0040] The first stage of the line under consideration, which is traversed by the gas in the direction of circulation of the compressed gas in the system, is called the "first" compression or expansion stage.

[0041] The last stage of the line under consideration, which is traversed by the gas in the direction of circulation of the compressed gas in the system, is called the "last" compression or expansion stage.

[0042] Each means of heat storage and recovery makes it possible to recover thermal energy in addition to the energy of the compressed gas, which makes it possible to improve the efficiency of the system, the thermal energy being recovered by the compressed gas during the expansion phase.

[0043] The means for storing and recovering heat can be direct or indirect means for storing and recovering heat.

[0044] By "direct heat storage and recovery means," it is understood that this heat storage and recovery means allows for a direct heat exchange between the compressed gas (the heat from which is to be recovered during the compression phase and which is to be heated during the expansion phase) and a heat storage material (which may be liquid, gaseous, or solid, such as beads or gravel). In other words, it may be a direct heat exchanger between the compressed gas and a heat storage and recovery material, such as a tank containing beads or gravel of a heat storage material.

[0045] By "indirect heat storage and recovery means", it is understood that this A heat storage and recovery system allows for indirect heat exchange between a compressed gas (whose heat is recovered during compression and which is heated during expansion) and a heat storage material (advantageously a liquid or gaseous fluid). The heat storage material is separated from the compressed gas by a wall, thus preventing direct heat exchange between these two elements, hence the term "indirect exchange." In other words, it can be an indirect heat exchanger, such as a tube or plate heat exchanger, to allow heat exchange between the compressed gas and a heat storage and recovery fluid.

[0046] The means of storing the compressed gas can be an artificial reservoir or, more advantageously, an underground cavity, such as a salt cavern, an old mine or an aquifer.

[0047] Preferably, the system may comprise as many compression stages as expansion stages. Thus, the heat storage and recovery means of each compression stage may be used in one (and only one) expansion stage, preferably operating at substantially the same pressure level. Alternatively, the system may comprise a different number of compression stages than expansion stages.

[0048] According to the invention, the energy storage and recovery system comprises at least one mechanical connection / disconnection means for mechanically connecting / disconnecting at least one compression means (preferably each compression means) of a compression stage to at least one expansion means of an expansion stage, preferably to a single expansion means of an expansion stage. The connection / disconnection means may, in particular, mechanically connect / disconnect a shaft of the compression means to a shaft of the expansion means, such that one of these shafts drives the other in rotation.

[0049] Several configurations can be considered: - A single release means can be coupled or decoupled from a single compression means by the connection / disconnection means; - Several relaxation means can be coupled or decoupled to a single compression means by at least one connection / disconnection means (one connection / disconnection means for each relaxation means for example); - A single relaxation means can be coupled or decoupled to several compression means by the connection / disconnection means (one connection / disconnection means for each compression means for example). - Several relaxation means can be coupled or decoupled from several compression means by means of connection / disconnection (a means connection / disconnection for each compression method and / or for each release method, for example).

[0050] In addition, the system may include several of the above configurations, for example one compression means coupled / decoupled to a single turbine and two other compression means may be coupled / decoupled to two other turbines (or to a single turbine).

[0051] By means of the connection / disconnection means, at least one compression means can be coupled to at least one associated release means, which facilitates the starting of the compression means to which it is associated. In other words, the release means causes the compression means to start via the connection / disconnection means. This configuration also allows the compression means to start quickly (in less than 2 minutes, for example).

[0052] The connection / disconnection means also allows the compression means to be disconnected from the expansion means to which it may be connected, once the compressor start-up phase is complete. This allows heat to be stored in the two heat storage and recovery means for each compression stage and in the two compressed gas storage means. This disconnection allows the compression phase to continue independently of the expansion phase (and vice versa).

[0053] Preferably, each connection / disconnection means can be configured to couple / disconnect at least one compression means to at least one expansion means which operates substantially at the same torque and / or the same power and / or the same rotational speed.

[0054] According to an advantageous configuration of the invention, each compression stage of the compression line can be defined by a passage number (or sequence) corresponding to the sequence of passage of the compressed gas through that compression stage within the compression line, and each expansion stage of the expansion line can be defined by an outlet number corresponding to the sequence of that expansion stage within the expansion line, in the reverse direction of the passage of the compressed gas through the expansion line. Furthermore, each connection / disconnection means can be configured to connect / disconnect the compression means of the compression stage with the defined passage number to the expansion means of the expansion stage with the defined outlet number, the defined passage number being equal to the outlet number.Thus, each compression device can be connected to an expansion device operating at substantially the same torque and / or power, preferably with substantially the same pressure (at the same pressure level) of the compressed gas, and therefore substantially the same rotational speed. Indeed, in the compression line, the pressure increases in each successive compression stage, whereas in the expansion line, the... pressure gradually decreases in each successive expansion stage (in the direction of gas flow in the expansion line and in the compression line).

[0055] Preferably, the compression line may comprise three compression stages and the expansion line may comprise three expansion stages. This configuration generally allows for good system efficiency while limiting the number of compression and expansion stages. It therefore offers a good compromise between performance and size / mass.

[0056] For this variant, the system may include a first connection / disconnection means for the connection between the compression means of the last compression stage (i.e. the compression stage whose pass number is three) and the expansion means of the first expansion stage (i.e. the expansion stage whose output number is three),a second connection / disconnection means for connecting the compression means of the intermediate compression stage (i.e., the compression stage with passage number two) to the expansion means of the intermediate expansion stage (i.e., the expansion stage with output number two), and a third connection / disconnection means for connecting the compression means of the first compression stage (i.e., the compression stage with passage number one) to the expansion means of the last expansion stage (i.e., the expansion stage with output number one). Thus, each compression means can be connected to an expansion means operating at substantially the same torque and / or power, preferably with substantially the same compressed gas pressure, and therefore substantially the same rotational speed. Indeed,The first compression means and the last expansion means operate substantially at low pressure, the intermediate compression means and expansion means operate substantially at medium pressure, and the last compression means and the first expansion means operate substantially at high pressure, the terms "low", "medium" and "high" being relative to the different compression and expansion stages respectively.

[0057] Preferably, at least one (preferably each) connection / disconnection means may include a shaft for mechanically connecting at least one compression means to at least one expansion means. The shaft provides a mechanical connection capable of transmitting the high power required to drive the compression means, while minimizing efficiency losses.

[0058] Advantageously, at least one (preferably each) connection / disconnection means may include a clutch that allows each compression means to be connected or disconnected to the expansion means to which it can be connected / disconnected. The clutch provides a reliable connection capable of transmitting the power necessary to drive the compression means.

[0059] Preferably, the clutch can be mounted on a shaft connected to one of said compression or release means, and the clutch can be connected to the other of said compression or release means. Thus, the connection / disconnection means is simple and robust.

[0060] Advantageously, the shaft can be short (of short length, for example whose length is less than or equal to 3 times its diameter) so as to increase its reliability and limit the risks of failures.

[0061] According to an advantageous configuration of the invention, each compression stage may include a cooling means downstream (in the direction of compressed gas flow) of said means, and at least two heat storage and recovery means so as to cool the gas to the maximum extent possible before it enters the next compression stage or the compressed gas storage means. Furthermore, each compression stage may also include a gas / liquid separation means downstream (in the direction of compressed gas flow) of the cooling means. Indeed, during the cooling of the compressed gas, condensation may occur. This water, in liquid form, may originate from the water vapor initially contained in the extracted gas, particularly if it is ambient air, and it may damage the compression means of the next stage or the compressed gas storage means, particularly if it is a compressor.The gas / liquid separation method then makes it possible to eliminate the liquid phase contained in the compressed gas.

[0062] Preferably, at least one expansion means, preferably each expansion means, can be connected to an electric machine capable of generating electricity during the expansion phase and capable of assisting in starting the compression means at the start of the compression phase. Thus, each electric machine can participate, in motor mode, in driving a compression means to facilitate their starting.

[0063] According to an advantageous embodiment of the invention, first valves and / or second valves can be positioned upstream and / or downstream of each heat storage and recovery means, so as to permit or not the passage of compressed gas into the heat storage and recovery means and to permit or not this passage into the expansion line or into the compression line, the heat storage and recovery means being used both for storage in the compression phase and for energy recovery in the expansion phase.

[0064] Preferably, the first and / or second valves may include three-position valves to direct the gas from the compression line or from the expansion line and / or to the compression line or to the expansion line.

[0065] Alternatively or additionally, of the first and second means Opening / closing valves (which can also be third and fourth valves respectively) can be positioned upstream and / or downstream of each compressed gas storage means, so as to permit or not the passage of compressed gas into the compressed gas storage means and to permit or not this passage arriving from the compression line or leaving towards the expansion line, the compressed gas storage means being used both for storage in the compression phase and for energy recovery in the expansion phase.

[0066] The invention also relates to a compressed gas energy storage and recovery method, in which a compressed gas energy storage and recovery system is used according to one of the variants or combinations of variants described above. The method may, in particular, include a compression step, a compressed gas storage step, and an expansion step. Furthermore, in this method, the heat generated from the gas during the compression step is recovered and used to reheat the gas before it is expanded during the expansion phase. This method carries out at least the following steps: - During the expansion phase, the compressed gas in said at least two compressed gas storage means is expanded and the expansion phase is stopped when the compressed gas pressure in at least one of said at least two compressed gas storage means reaches a predetermined pressure and / or when the outlet temperature of at least one of the heat storage and recovery means reaches a predefined temperature; - At the start of the compression phase, the remaining compressed gas from at least one of the at least two compressed gas storage means is sent to the expansion line, and in each expansion stage, the remaining heat from at least one of the heat storage and recovery means is recovered before the compressed gas is passed through the expansion means of that expansion stage. The expansion means is then mechanically connected to a compression means of a compression stage via a connection / disconnection means. The compressed air exiting each compression means then passes through at least one other heat storage and recovery means, such that each heat storage and recovery means is dedicated either to operation on the expansion line or to operation on the compression line. Then, once the compression phase has started, and preferably once the compressed gas has been completely discharged from the at least two compressed gas storage means, the disconnection of each connection / disconnection means is activated so as to mechanically disconnect the compression means from the associated expansion means, and the compression means are then driven by an electric motor. mechanically connected by means of compression.

[0067] By this process, we take advantage of a part of the compressed gas remaining in one of the two compressed gas storage means and of a part of the heat remaining in one of the two heat storage and recovery means of each compression stage, to power the turbines which will help drive the rotation of the compression means to facilitate their start-up and to accelerate it.

[0068] Advantageously, before mechanically activating the disconnection of each connection / disconnection means, the heat contained in the heat storage and recovery means can be discharged, so as to recover all the thermal energy from the compression phase.

[0069] Preferably, when starting the compression phase, alternatively or additionally to the use of compressed gas exiting the compressed gas storage means, each electrical machine connected to the expansion means, connected to the associated compression means by the connection / disconnection means, can be used to participate in starting the compression means.

[0070] Fig. 2 illustrates, schematically and not in a limiting manner, a compressed air energy storage and production system according to the invention.

[0071] The system comprises a compression line (1), with several compression stages (3), here three compression stages, but a different number could be used. Each compression stage (3) comprises a compression means (100, 101, 102) (which may be compressors, for example). The number of compression stages may depend on the air pressure to be achieved and on the recommendations of the suppliers. The compression means (100, 101, 102) may be axial or centrifugal compressors, for example. Compression means (100) is here a low-pressure compressor, compression means (101) is here a medium-pressure compressor, and compression means (102) is here a high-pressure compressor. The compressed gas (10) in the process is ambient air, containing a water saturation related to its temperature and pressure, but another gas could, of course, be used.

[0072] In the compression line (1), the gas is compressed and then sent to two compressed gas storage means (1000A) and (1000B). These compressed gas storage means (1000A) and (1000B) are arranged in parallel and are suitable for high pressures. These compressed gas storage means (1000A) and (1000B) can be natural cavities such as a salt cavern, an old mine, or an aquifer, or artificial storage facilities such as reservoirs.

[0073] After each compression means (100, 101, 102), at least two heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) are arranged in parallel to cool the hot compressed air exiting the compression. while storing this thermal energy. Heat storage and recovery devices (200A and 200B) are suitable for low pressure, heat storage and recovery devices (201A and 201B) are suitable for medium pressure, and heat storage and recovery devices (202A and 202B) are suitable for high pressure. Thermal energy exchange / storage can be achieved through direct contact between hot compressed gas and an inert material, or through indirect contact between hot compressed air and a fluid (gas or liquid) or a solid. In the case of direct contact, the material can be stones, concrete, gravel, or any other suitable solid material. In the case of indirect contact, the exchange fluid can be any heat transfer fluid suitable for the temperature and pressure conditions.

[0074] Cooling means (300, 301, 302) may be arranged downstream of the heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) if necessary to complete the cooling of the compressed gas before the next compression stage or before its storage. Once the gas has been cooled and before the next compression stage, the condensed water, resulting from the humidity of the gas (particularly when it is ambient air), is extracted from the air compression stream by gas-liquid separation means (400, 401, 402) (separators, for example) in order to obtain, at the inlet of the compression means of the next compression stage or of the compressed gas storage means, a gas free of liquid, in particular free of liquid water. This condensation of water can take place in the heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) and / or in the cooling means (300, 301, 302).

[0075] The system includes an expansion line (2), with several expansion stages (4), here three expansion stages but a different number could be used provided that it is identical to the number of compression stages.

[0076] Each expansion stage (4) includes an expansion means (700, 701, 702). The expansion means (700) is here a high-pressure turbine, the expansion means (701) is here a medium-pressure turbine, and the expansion means (702) is here a low-pressure turbine.

[0077] In the expansion line (2), the compressed gas is expanded via the expansion means (700, 701, 702) of the expansion stages (4) in order to produce electricity via alternators, not shown in the diagram, one alternator (an electrical machine) being connected to each expansion means (700, 701, 702). Connection / disconnection means C allow each compression means and each associated expansion means to be coupled or discoupled at the same pressure level. These connection / disconnection means C may, in particular, include a connecting shaft and a clutch. The low-pressure compression means (100) is connected by a first connection / disconnection means C to the low-pressure expansion means (702). The medium-pressure compression means (101) is connected by a second connection / disconnection means C to the medium-pressure expansion means (701). The high-pressure compression means (102) is connected by a third connection / disconnection means C to the high-pressure expansion means (700). In order to improve the efficiency of each expansion means, the thermal energy stored in the heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) is returned to the gas flow upstream of each expansion means according to its pressure range.

[0078] At the end of the expansion phase preceding the compression phase, the compressed gas storage means (1000A) is discharged of the compressed gas it contains and the compressed gas storage means (1000B) is partially discharged of its compressed gas: in other words, a reserve of compressed gas is kept in only one of the two compressed gas storage means so that it can be used for starting the compression means during the next compression phase.Similarly, the first heat storage and recovery means (200A, 201A, 202A) are discharged of their thermal energy and the second heat storage and recovery means (200B, 201B, 202B), those which are in parallel with the said first heat storage and recovery means (200A, 201A, 202A) respectively, are partially discharged of their thermal energy: in other words, a reserve of heat to be recovered is kept in only one of the two parallel heat storage and recovery means of each stage, in order to be used to facilitate the start-up of the compression means in the next compression phase.The second compressed gas storage means (1000B) thus maintains a sufficient reserve of compressed gas, and the second heat storage and recovery means (200B, 201B, 202B) each maintain a sufficient reserve of thermal energy to provide the energy needed to overcome the inertia of starting the compressors in the next compression phase.

[0079] Figure 3 illustrates, schematically and without limitation, the start-up phase compression means with the compressed gas energy storage and recovery system of [Fig.2] according to the invention.

[0080] During the start of the next compression phase, the gas remaining in the (second) compressed gas storage means (1000B) is sent to the second high-pressure heat storage and recovery means (202B). The compressed gas then heats up and enters the high-pressure expansion means (700). From the outlet of the high-pressure expansion means (700), the compressed gas flow is sent to the second medium-pressure heat storage and recovery means (201B). The compressed gas then heats up and enters the means medium-pressure expansion unit (701). Finally, at the outlet of the medium-pressure expansion unit (701), the compressed gas flow is sent to the second low-pressure heat storage and recovery unit (200B). The compressed gas then heats up and enters the low-pressure expansion unit (701) to be expanded, preferably to atmospheric pressure.

[0081] The low-pressure compression means (100) compresses the incoming gas, in this case atmospheric air (10). The hot, compressed gas exiting the compression means (100) is sent only to the first low-pressure heat storage and recovery means (200A), because the second low-pressure heat storage and recovery means (200B) is used to expand the compressed gas from the second compressed gas storage means (1000B) and to start the low-pressure compression means (100). Once cooled in the first low-pressure heat storage and recovery means (200A) and possibly in the cooling means (300), the compressed gas stream may then include water from the humidity in the air, condensed during the cooling phases in the heat storage and recovery means (200A) and / or in the cooling means (300).This condensed water can advantageously be separated from the compression line in the gas-liquid separation means (400) (which is therefore optional) operating at the flow pressure. The gas is then compressed by the medium-pressure compression means (101). The compressed and hot gas is sent only to the first medium-pressure heat storage and recovery means (201A), because the second medium-pressure heat storage and recovery means (201B) participates in the expansion of the compressed gas from the second compressed gas storage means (1000B) and used to start the medium-pressure compression means (101).Once cooled in the first medium-pressure heat storage and recovery unit (201A) and optionally in the cooling unit (301), the compressed gas stream may contain water from atmospheric humidity, condensed during the cooling phases in the first heat storage and recovery unit (201A) and / or in the cooling unit (301). This condensed water can then be advantageously separated from the compression line in the gas-liquid separation unit (401) (which is therefore optional), operating at the flow pressure. The gas is then compressed by the high-pressure compression unit (102).The hot, compressed gas is sent only to the first high-pressure heat storage and recovery unit (202A), as the second high-pressure heat storage and recovery unit (202B) is used to expand the compressed gas from the second compressed gas storage unit (1000B) and to start the high-pressure compression unit (102). Once cooled in the... In the first high-pressure heat storage and recovery unit (202A) and optionally in the cooling unit (302), the compressed gas flow may include water, originating from atmospheric humidity, condensed during the cooling phases in the first heat storage and recovery unit (202A) and / or in the cooling unit (302). This condensed water can advantageously be separated from the compression line in the gas-liquid separation unit (402) (which is therefore optional) operating at the flow pressure. The gas is then sent only to the first compressed gas storage unit (1000A), the second compressed gas storage unit (1000B) being used for expansion.

[0082] During this start-up phase of the compression means, the connection / disconnection means C allow each compression means (associated with an electric motor for driving the compression means after the start-up phase) to be coupled to an expansion means (preferably at substantially the same pressure). In other words, each compression means (associated with an electric motor) is coupled to an expansion means by a connection / disconnection means C. Indeed, the start-up issue concerns both the compression means and the electric motor to which it is connected. Once the inertia of both is overcome, that is, after the start-up phase, the electrical supply to the electric motor is sufficient to drive the compression means.

[0083] In order to direct the gas flow of the compression phase and the expansion phase, in the heat storage and recovery means and in the compressed gas storage means, valves (not shown) or other opening / closing means are used upstream and / or downstream of each of these means.

[0084] Once the inertia period of compressor start-up is over, the compressed gas storage means (1000B) and the heat storage and recovery means (200B, 201B, 202B) are discharged of their compressed gas and thermal energy, respectively. The expansion means (700, 701, 702) cease to operate and are disconnected from the compression means (100, 101, 102) via the connection / disconnection means C. The compression means (100, 101, 102) then draw their power from the electrical grid via electric motors to which they are connected, for example, for the remainder of the compression phase.During the compression phase, once the heat storage and recovery units (200B, 201B, 202B) have been discharged, the hot compressed gas can then simultaneously charge all the heat storage and recovery units (200A, 200B, 201A, 201B, 202A, 202B) using the first and second valves upstream and / or downstream of the heat storage and recovery units (200A, 200B, 201A, 201B, 202A, 202B). Similarly, once the second compressed gas storage unit (1000B) is empty. Once discharged, the compressed gas can then be stored in parallel in the compressed gas storage means (1000A) and (1000B) by using the first and second opening means upstream and / or downstream of the compressed gas storage means.

[0085] In this mode of operation, the connection / disconnection means C allow each compression means to be decoupled from the expansion means (preferably at substantially the same pressure) to which it may be coupled. In other words, each compression means is decoupled from its associated expansion means by the connection / disconnection means C.

[0086] At the end of the compression phase, once the first heat storage and recovery means (200A, 201A, 202A) are fully charged, the hot compressed gas is directed only to the second heat storage and recovery means (200B, 201B, 202B) to complete their thermal energy charging. Similarly, once the first compressed gas storage means (1000A) is fully charged, the compressed gas is directed only to the second compressed gas storage means (1000B) to complete its compressed gas charging.

[0087] In this mode of operation, the connection / disconnection means C allow each compression means to be decoupled from the expansion means (preferably at substantially the same pressure) to which it may be coupled. In other words, each compression means is decoupled from its associated expansion means by the connection / disconnection means C.

[0088] Thanks to the invention, the compression-expansion means coupling by a connection / disconnection means (including in particular a mechanical shaft and a clutch) for each pressure stage (compression / expansion substantially at the same pressure level) makes it possible to overcome the inertia of the start-up of the compression means and to reduce the peak of electrical demand on the electrical network at the beginning of the compression phase.

[0089] For each pressure stage (compression / expansion at substantially the same pressure level), expanding the compressed gas via the expansion means actuates the connection / disconnection means, which is then coupled to the associated compression means. This allows the compression means associated with each expansion means to be driven. The energy required to start the compression means, and especially to meet the energy peak due to start-up inertia, is then supplied by the compressed gas from the end of the previous expansion phase, thus smoothing the impact of energy demand on the network.

Claims

Claims

1. Compressed gas energy storage and recovery system comprising: - a gas compression line (1) with at least one compression stage (3), each compression stage (3) comprising a compression means (100, 101, 102) and at least two heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) downstream, in the direction of gas circulation, of said compression means (100, 101, 102), the at least two heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) being mounted in parallel, - at least two compressed gas storage means (1000A, 1000B) located at the outlet of the gas compression line (1) for storing the gas compressed, said at least two compressed gas storage means (1000A, 1000B) being mounted in parallel, - an expansion line (2) for expanding compressed gas stored in the compressed gas storage means (1000A, 1000B),the expansion line (2) comprising at least one expansion stage (4), each expansion stage (4) comprising pipes and an expansion means (700, 701, 702), the pipes being configured to circulate the compressed gas in said at least two heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) of the same compression stage so as to heat the compressed gas before the expansion means (700, 701, 702), characterized in that the energy storage and recovery system comprises at least one mechanical connection / disconnection means (C) for connecting / disconnecting at least one compression means (100, 101, 102) of a compression stage to at least one expansion means (700, 701, 702) of an expansion stage, preferably to a single means of relaxation (700, 701, 702) of an relaxation stage.,

2. Compressed gas energy storage and recovery system according to claim 1, wherein the system comprises as many compression stages (3) as expansion stages (4).

3. Compressed gas energy storage and recovery system according to claim 2, wherein each compression stage (3) of the compression line (1) is defined by a passage number, the passage number corresponding to the order of passage of the compressed gas in this compression stage (3) within the compression line (1), for which each expansion stage (4) of the expansion line (2) is defined by an output number, the output number corresponding to the order of this expansion stage (4) within the expansion line (2), in the opposite direction to the passage of the compressed gas in the expansion line and for which each connection / disconnection means (C) is configured to connect / disconnect the compression means (100, 101, 102) of the compression stage (3) of the defined passage number by means of the expansion stage (4) of the defined output number, the defined passage number being equal to the output number.

4. Compressed gas energy storage and recovery system according to one of claims 2 or 3, for which the compression line (1) comprises three compression stages (3) and the expansion line (2) comprises three expansion stages (4).

5. Compressed gas energy storage and recovery system according to claim 4, wherein the system comprises a first connection / disconnection means (C) for the connection between the compression means (100) of the last compression stage and the expansion means (702) of the first expansion stage, a second connection / disconnection means (C) for the connection between the compression means (101) of the intermediate compression stage and the expansion means (701) of the intermediate expansion stage and a third connection / disconnection means (C) for the connection between the compression means (102) of the first compression stage and the expansion means (700) of the last expansion stage.

6. Compressed gas energy storage and recovery system according to one of the preceding claims, wherein the at least one connection / disconnection means (C) comprises a shaft for mechanically connecting at least one compression means (100, 101, 102) to at least one expansion means (700, 701, 702).

7. Compressed gas energy storage and recovery system according to one of the preceding claims, wherein the at least one connection / disconnection means (C) comprises a clutch.

8. Compressed gas energy storage and recovery system according to one of the preceding claims, for which each compression stage (1) comprises a cooling means (300, 301, 302) downstream of said at least two heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) and preferably a gas / liquid separation means (400, 401, 402), downstream of the cooling means (300, 301, 302).

9. Compressed gas energy storage and recovery system according to one of the preceding claims, in which at least one expansion means (700, 701, 702), preferably each expansion means, is connected to an electrical machine capable of generating electricity in the expansion phase and capable of participating in the starting of the compression means (100, 101, 102) at the start of the compression phase.

10. Compressed gas energy storage and recovery system according to one of the preceding claims, in which first valves and / or second valves are positioned upstream and / or downstream of each heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B).

11. Compressed gas energy storage and recovery system according to one of the preceding claims, in which first and second opening / closing means are positioned upstream and / or downstream of each compressed gas storage means (1000A, 1000B).

12. A method for storing and recovering energy using compressed gas, in which a compressed gas energy storage and recovery system according to one of the preceding claims is used, and in which at least the following steps are carried out: - In the expansion phase, the compressed gas from said at least two compressed gas storage means (1000A, 1000B) is expanded and the expansion phase is stopped when the compressed gas pressure in at least one of said at least two compressed gas storage means (1000A, 1000B) reaches a predetermined pressure and / or when the outlet temperature of at least one of the heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) reaches a predefined temperature;- At the time of starting the compression phase, the remaining compressed gas is transferred into at least one of said at least two compressed gas storage means (1000A, 1000B), into the expansion line (2) and, in each expansion stage (4), the remaining heat is recovered from said heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) before passing the compressed gas into the expansion means (700, 701, 702), the expansion means (700,; 701, 702) then being mechanically connected to a compression means (100, 101, 102) of a compression stage (3), by means of a connection / disconnection means (C); then when the compression phase has started and once the compressed gas is completely discharged from said at least two compressed gas storage means (1000A, 1000B), the disconnection of each connection / disconnection means (C) is activated so as to mechanically disconnect the compression means (100, 102, 102) from the associated expansion means (700, 701, 702) and the compression means (100, 101, 102) are then driven by an electric motor.

13. Method for storing and recovering energy by compressed gas according to claim 12, in which before mechanically activating the disconnection of each connection / disconnection means (C), the heat contained in the heat storage and recovery means (200A, 200B, 201A, 201B, 202A, 202B) is discharged.

14. Method for storing and recovering energy according to one of claims 12 or 13, using the energy storage and recovery system according to claim 9, in which, when starting the compression phase, alternatively or additionally to the use of the compressed gas leaving the compressed gas storage means (1000A, 1000B), each electrical machine connected to the expansion means (700, 701, 702) is used to participate in starting the compression means (100, 101, 102).

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