energy storage and recovery process with indirect heat storage by compression

Abstract

The present invention relates to a system and method for storing and recovering energy using compressed gas, comprising: - a gas compression line (1) with at least two compression stages (3), each comprising a heat storage device downstream of a compression means (100, 101, 102), - on one compression stage (3), the heat storage device comprises a heat storage means (200, 201) for directly exchanging heat between the compressed gas and heat storage particles, and - on another compression stage (3), the heat storage device comprises a cooling loop with a heat exchanger (800) for exchanging heat between the compressed gas and a heat transfer fluid, and a heat storage means (203) for directly exchanging heat between the storage particles and the heat transfer fluid. Figure 4 to be published

Description

Title of the invention: energy storage and recovery method with indirect heat storage by compression Technical field

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

[0002] While global energy objectives aim to promote renewable energies in order to gradually increase the proportion of renewable energies in the energy mix, the variable and intermittent nature of these renewable energies remains their major drawback. To address this problem, energy storage appears to be a very advantageous solution. By storing the surplus energy produced at peak production in order to have it available when it becomes lower than demand, storage overcomes the constraint of variability and provides flexibility, even continuity, to renewable energies. Thus, the need for energy storage processes and systems is expected to increase in the coming years, with the proportion of renewable energies in the global mix.

[0003] Many storage technologies currently exist, such as mechanical storage such as Pumped Storage Stations (PSST) using hydroelectricity produced by two water reservoirs located at different altitudes. In the electricity storage phase, water from the lower reservoir is pumped to the upper reservoir and stored at this altitude. When the demand for electricity increases, the water from the upper reservoir is returned to the lower reservoir through a hydraulic turbine which will then generate electricity via an alternator. Hydroelectric dams also operate on the same concept: the dam retains water at a higher altitude upstream than downstream and when the demand for electricity increases, the dam releases the water by passing it through hydraulic turbine alternators producing electricity.

[0004] Compressed air energy storage and recovery, known as CAES (from the English "Compressed Air Energy Storage") is a technology for which a first installation was built in Germany at the end of the 1970s, with a power of 290 MW. The principle of this technology is to use the electricity produced and not consumed to compress a gas, typically air. In order to avoid any damage to the compressors, the heat resulting from the compression is evacuated between each stage. The compressed air at medium or high pressure (40 bar to 300 bar) is sent to a natural type of storage such as a salt cavern, a mine (salt, limestone, coal) or in artificial storage while waiting for the energy discharge phase. During the electricity production phase, the stored air is extracted from the storage to be expanded in turbo-alternators, after being heated in a combustion chamber.

[0005] 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 evacuated between each stage, i.e. lost, but stored in order to be able to heat the air upstream of the turbines in the energy recovery phase. Thanks to this reuse of thermal energy internal to the process, the efficiency of AACAES can reach approximately 70% instead of approximately 50% for the CAES process. The air can be cooled in the compression phase in a heat exchanger with a heat transfer fluid. The hot heat transfer fluid will then be stored in order to be able to release its heat to the air during the expansion phase.

[0006] However, these systems require improvements to limit the size and / or mass of the system, and / or its cost so that the system is economically relevant. Prior art

[0007] A first solution to limit damage to the compressors is to extract the water from the compression line, by means of a gas / liquid separator provided at each compression stage. [Fig.l] of the prior art illustrates, schematically in the form of a block diagram, such an AACAES system and method. In this figure, the phase of energy storage by compression of a gas, and the phase of energy production by expansion of a gas are represented. The system according to the prior art consists of a compression line 1, including one or more compression stages 3 depending on the air pressure to be achieved as well as the suppliers' recommendations. In the illustrated embodiment, the compression line 1 comprises three compression stages 3. Each compression stage 3 comprises 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 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 compression line 1 and then sent to a compressed air storage means 1000 suitable for high pressures. Heat storage and recovery devices 200, 201, 202 are arranged after each compressor 100, 101, 102 of each compression stage 3 in order to cool the hot compressed air at the outlet of . compression while storing this thermal energy. The heat storage and recovery device 200 is suitable for low pressure, the heat storage and recovery device 201 is suitable for medium pressure, and the heat storage and recovery device 202 is suitable for high pressure. Cooling means 300, 301, 302 may be arranged after the heat storage and recovery devices 200, 201, 202 if necessary in order to finish cooling 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 air compression flow by gas-liquid separators 400, 401, 402 in order to have air at the compressor inlet without any trace of liquid water.This condensation of water can take place in the heat storage and recovery devices 200, 201, 202 and / or in the cooling means 300, 301, 302. During the energy production phase, the compressed air is expanded via one or more turbines 700, 701, 702 of an expansion stage, in order to produce electricity via alternators, 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. For this system and this method, the condensed water is just extracted, the associated energy is therefore lost.

[0008] The system of [Fig. 2] is also known from the applicant's patent application, the filing number of which is FR 20 / 12.637. This figure shows the phase of energy storage by compression of a gas, and the phase of energy production by expansion of a gas. The system consists of a compression line 1, including one or more compression stages 3 depending on the air pressure to be reached. In the illustrated embodiment, the compression line 1 comprises three compression stages 3. Each compression stage 3 comprises a compression means 100, 101, 102, also called a compressor. The compressor 100 is a low-pressure compressor, the compressor 101 is a medium-pressure compressor, and the compressor 102 is a high-pressure compressor. The gas used 10 in the illustrated process is ambient air, containing a water saturation linked 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 means 1000 suitable for high pressures. Heat storage and recovery devices 200, 201, 202 are arranged after each compressor 100, 101, 102 of each compression stage 3 in order to cool the hot compressed air at the compression outlet while storing this thermal energy. The heat storage and recovery device 200 is suitable for low pressure, the heat storage and recovery device 201 is suitable for medium pressure and the heat storage and recovery device 202 is suitable for . high pressure. Cooling means 300, 301, 302 may be arranged after the heat storage and recovery devices 200, 201, 202 if necessary in order to finish cooling 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 air compression flow by gas-liquid separators 400, 401, 402 in order to have air at the compressor inlet without any trace of liquid water. This condensation of water can take place in the heat storage and recovery devices 200, 201, 202 and / or in the cooling means 300, 301, 302. The water condensed at each compression stage is then sent to liquid storage means 500, 501, 502.The storage means 500 is suitable for low pressures, the storage means 501 is suitable for medium pressures and the storage means 502 is suitable for high pressures. During the energy production phase in the expansion line 2, the compressed air is expanded via one or more turbines 700, 701, 702 on each expansion stage 4, according to the suppliers' recommendations, in order to produce electricity via alternators, not shown in the diagram. The turbine 702 is a low pressure turbine, the turbine 701 is a medium pressure turbine and the turbine 700 is a high pressure turbine. In order to improve the efficiency of each turbine, the thermal energy stored in the heat storage and recovery devices 200, 201, 202 is returned to the air flow upstream of each turbine in accordance with its pressure range.Finally, in order to also improve the production of electricity, the condensed water previously stored in the liquid storage means 500, 501, 502 is reinjected upstream of each turbine of the associated pressure range via mixing means 600, 601, 602 (also called mixers) in order to increase the flow rate in each turbine. The condensed water is then optimally reused in the expansion phase and its associated energy is no longer lost.

[0009] In these prior art systems, the heat storage and recovery devices 200, 201 and 202 consist of reservoirs (cylindrical for example) containing heat storage particles (concrete balls or gravel for example). These are direct heat storage and recovery devices capable of storing heat directly by contact between the compressed gas and the heat storage particles. Thus, when the hot compressed fluid (leaving one of the compressors 100, 101 or 102) arrives in the heat storage and recovery device 200, 201 or 202, its heat is transferred directly to the heat storage particles. The compressed fluid thus emerges cooled from the heat storage and recovery device 200, 201 or 202, the heat being stored in the heat storage particles.

[0010] Upon expansion, the compressed fluid is reheated before passing into the turbines 700, 701 or 702. For this, the compressed fluid passes again through the heat storage and recovery device 200, 201 or 202 where the heat storage particles have previously stored heat (during the compression step as described in the previous paragraph). Thus, the heat from the heat storage particles will be transferred to the compressed fluid which will thus leave the heat storage and recovery device 200, 201 or 202 hotter than it entered. The storage particles are cooled and can therefore be reused again during a compression step to cool the hot compressed fluid leaving a compressor 100, 101 or 102.

[0011] As the heat storage and recovery devices 200, 201 or 202 are subjected to the pressure of the compressed fluid, they require significant masses so that the reservoir can withstand the internal pressure. This is particularly the case for the heat storage and recovery device 202 subjected to the highest pressure (last compression stage before the storage of the compressed fluid in the compressed air storage means 1000). As the thickness of the casing of this reservoir of the heat storage and recovery device is significant, its cost is high and the logistics operations (for installation in particular) are more complex. Summary of the invention

[0012] The object of the invention is to reduce the size and mass of the heat storage and recovery device, and therefore those of the system, in particular to reduce their cost, while maintaining the energy performance of the system (mainly the efficiency).

[0013] This aim is achieved by a compressed gas energy storage and recovery system comprising:

[0014] - a gas compression line with at least two compression stages, each compression stage comprising a compression means and a heat storage and recovery device positioned downstream of the compression means, in the direction of circulation of the gas in the compression stage,

[0015] - at least one means of storing compressed gas located at the outlet of the communication line gas pressure to store compressed gas,

[0016] - an expansion line for expanding the compressed gas stored in the means of compressed gas storage, the expansion line comprising at least two successive expansion stages, each expansion stage comprising pipes and an expansion means, the pipes of each expansion stage being configured to circulate the compressed gas in at least one device for storing and recovering the heat from the compression stages so as to heat the compressed gas before the expansion means. In addition: - on at least one of the compression stages, the heat storage and recovery device is a direct heat storage and recovery device comprising at least a first heat storage and recovery means comprising first heat storage particles, the first heat storage and recovery means being configured to directly exchange heat directly between the compressed gas and the first heat storage particles, and - on at least the last compression stage, in the direction of circulation of the compressed gas, the heat storage and recovery device is an indirect heat storage and recovery device comprising a cooling loop, the cooling loop comprising a heat exchanger without direct contact for exchanging heat between the compressed gas and a heat transfer fluid capable of circulating in the cooling loop, the cooling loop comprising a second heat storage and recovery means comprising second heat storage particles, the second heat storage and recovery means being configured to exchange heat directly between the second storage particles and the heat transfer fluid.

[0017] The invention also relates to a method for storing and recovering energy using compressed gas comprising at least the following steps:

[0018] - In the energy storage phase:

[0019] a) a gas is compressed at least once in a compression line comprising at least two compression stages, each compression stage comprising at least one compression means;

[0020] b) after each compression step, the heat of said compressed gas is recovered in at least one heat storage and recovery device; the heat storage and recovery step of at least the last compression step implementing an indirect heat storage and recovery step with a cooling loop comprising a heat exchanger without direct contact (also called "indirect contact") for exchanging heat between the compressed gas and a heat transfer fluid and a (second) heat storage and recovery means comprising (second) storage particles, and the heat storage and recovery step of at least one other compression step implementing a direct heat storage and recovery step.

[0021] c) the cooled compressed gas is stored in at least one compressed gas storage means.

[0022] - In the energy recovery phase:

[0023] d) the compressed gas leaving the compressed gas storage means is circulated in an expansion line of at least two expansion stages, and in each expansion stage, the compressed gas is heated by circulating it in one of the heat storage and recovery devices (direct or indirect) using the heat stored during the compression stage and then the heated compressed gas is expanded in an expansion means.

[0024] The invention relates to a compressed gas energy storage and recovery system comprising:

[0025] - a gas compression line with at least two compression stages, each compression stage comprising a compression means and a heat storage and recovery device positioned downstream of the compression means, in the direction of circulation of the compressed gas in the compression stage,

[0026] - at least one means of storing compressed gas located at the outlet of the communication line gas pressure to store compressed gas,

[0027] - an expansion line for expanding compressed gas stored in the means of compressed gas storage, the expansion line comprising at least two successive expansion stages, each expansion stage comprising pipes and an expansion means, the pipes of each expansion stage being configured to circulate the compressed gas in at least one device for storing and recovering the heat from the compression stages so as to heat the compressed gas before the expansion means.

[0028] In addition: - on at least one of the compression stages, the heat storage and recovery device is a direct heat storage and recovery device comprising at least a first heat storage and recovery means comprising first heat storage particles, the first heat storage and recovery means being configured to exchange heat directly between the compressed gas and the first heat storage particles, and - on at least the last compression stage, in the direction of circulation of the compressed gas, the heat storage and recovery device is an indirect heat storage and recovery device comprising a cooling loop, the cooling loop comprising a heat exchanger without direct contact for exchanging heat between the compressed gas and a heat transfer fluid capable of circulating in the cooling loop, the cooling loop comprising a second heat storage and recovery means comprising second heat storage particles, the second heat storage and recovery means being configured to exchange heat directly between the second storage particles and the heat transfer fluid.

[0029] Preferably, the compression line comprises as many compression stages as the expansion line comprises expansion stages, each heat storage and recovery device of a compression stage being used in the expansion stage at the corresponding pressure, preferably the expansion line and the compression line each comprise three stages.

[0030] Advantageously, at least one compression stage comprises a first cooling means downstream of the heat storage and recovery device, preferably said cooling means comprising an air cooler.

[0031] Preferably, the cooling loop comprises a second cooling means downstream, in the direction of flow of the heat transfer fluid during the charging of the system, of the second heat storage and recovery means, preferably, said second cooling means comprising an air cooler.

[0032] According to one configuration of the invention, at least one compression stage comprises separation means for separating the compressed gas from a liquid phase before the compressed gas reaches the next compression stage or the compressed gas storage means, each compression stage preferably comprising liquid storage means for storing said liquid phase at the pressure of the compression stage.

[0033] Advantageously, at least one expansion stage comprises mixing means for mixing said compressed gas with said liquid phase leaving one of the liquid storage means of the compression stages, the mixing means being positioned upstream of said heat storage and recovery device.

[0034] According to one implementation of the invention, the pipes of at least the first expansion stage are configured to circulate the compressed gas in at least one indirect heat storage and recovery device and for which the pipes of at least one other expansion stage are configured to circulate the compressed gas in at least one direct heat storage and recovery device.

[0035] The invention also relates to a method for storing and recovering energy using compressed gas comprising at least the following steps:

[0036] - In the energy storage phase:

[0037] a) a gas is compressed at least once in a compression line comprising at least two compression stages, each compression stage comprising at least one compression means;

[0038] b) after each compression step, the heat from said compressed gas is recovered. in at least one heat storage and recovery device; the heat storage and recovery device of at least the last compression stage being an indirect heat storage and recovery device with a cooling loop comprising a heat exchanger for exchanging heat between the compressed gas and a heat transfer fluid, and a second heat storage and recovery means comprising second storage particles, and the heat storage and recovery device of at least one other stage being a direct heat storage and recovery device.

[0039] c) the cooled compressed gas is stored in at least one compressed gas storage means.

[0040] - In the energy recovery phase:

[0041] d) the compressed gas leaving the compressed gas storage means is circulated in an expansion line of at least two expansion stages, and in each expansion stage, the compressed gas is heated by circulating it in one of the heat storage and recovery devices using the heat stored during the compression step and then the heated compressed gas is expanded in an expansion means.

[0042] Advantageously, as many compression steps as expansion steps are carried out, and the heat storage and recovery device of each of steps b) is used to reheat the compressed gas from the expansion step to the corresponding pressure.

[0043] Preferably, the heat from the compressed gas is recovered by heat storage particles.

[0044] Advantageously, after each heat recovery step, the compressed gas at the outlet of the heat storage and recovery device is cooled in a first cooling means before the gas is sent to the next compression step or to the compressed gas storage means.

[0045] According to one implementation of the invention, when the heat storage and recovery device is an indirect heat storage and recovery device, the heat transfer fluid of the cooling loop is cooled by a second cooling means positioned on the cooling loop after the heat storage and recovery means.

[0046] According to an advantageous configuration of the invention, the compressed gas is separated from a liquid phase which it contains in a separation means, before the compressed gas is sent to the following compression stage or to the compressed gas storage means, the liquid leaving each separation means being stored or evacuated at the pressure at which it is in a liquid storage means.

[0047] Preferably, in each expansion stage, the stored liquid is injected by means liquid storage, and preferably, it is mixed with compressed gas, before each heating step. List of figures

[0048] Other characteristics and advantages of the system and / or method according to the invention will appear on reading the following description of non-limiting examples of embodiments, with reference to the figures appended and described below. [Fig 1]

[0049] [Fig.l], already described, represents a system and a method for storing and recovering energy by compressed gas of the prior art. [Fig 2]

[0050] [Fig.2], already described, represents another system and method for storing and recovering energy by compressed gas of the prior art. [Fig 3]

[0051] [Fig.3] represents a first embodiment of the system and method according to the invention. [Fig 4]

[0052] [Fig.4] represents a second embodiment of the system and method according to the invention. [Fig 5]

[0053] [Fig.5] represents a third embodiment of the system and method according to the invention. [Fig 6]

[0054] [Fig.6] illustrates a fourth embodiment of the system and method according to the invention. Description of the embodiments

[0055] The invention relates to a system for storing and recovering energy using compressed gas (compressed air for example, the air being advantageously taken from the ambient environment) comprising:

[0056] - a gas compression line with at least two compression stages (of preferably three compression stages) to compress the gas to a pressure at which the compressed gas will be stored. Each compression stage includes a compression means, such as a compressor, to increase the pressure of the compressed gas. The use of several compression stages (and therefore several compression means) makes it possible to stage the compression in stages in order to have a high pressure while having acceptable compression efficiencies. Each compression stage also includes a heat storage and recovery device positioned downstream (in the direction of circulation of the compressed gas in the compression stage) of the compression means. Indeed, the gas leaving the compression means is at a higher pressure and temperature than those at which it entered this compression means. However, it is preferable to cool the compressed gas before it reaches the next compression stage or the compressed gas storage means (if the gas passes through the last compression stage) in order to facilitate the compression of the next stage or to reduce the design and manufacturing constraints of the compressed gas storage means.

[0057] - at least one means of storing compressed gas located at the outlet of the communication line gas pressure (downstream of the last compression stage) to store the compressed gas. Since the compressed gas has been cooled beforehand, the compressed gas can be stored at a relatively low temperature (around 30°C instead of around 200 to 300°C if there was no heat storage and recovery device). The thermal constraints of the compressed gas storage means are therefore reduced on this component, which reduces its mass and therefore its cost.

[0058] - an expansion line for expanding the compressed gas stored in the means of compressed gas storage and thus recover the energy stored by the compressed gas in the compression line. The expansion line comprises at least two successive expansion stages, each expansion stage comprising pipes and an expansion means for recovering the energy of the pressurized fluid. The expansion means may in particular be a turbine which will transform the energy of the compressed fluid into rotary mechanical energy. This rotary mechanical energy can then be sent to a generator which will transform it into electrical energy. The pipes of each expansion stage are configured to circulate the compressed gas in at least one heat storage and recovery device of the compression stages so as to heat the compressed gas before the expansion means. Thus, in each expansion stage, the fluid is heated by one of the heat storage and recovery devices before reaching the expansion means.

[0059] Furthermore, on at least one of the compression stages, the heat storage and recovery device is a direct heat storage and recovery device comprising at least a first heat storage and recovery means comprising first heat storage particles. This first heat storage and recovery means may be a reservoir containing a fixed bed of first heat storage particles (concrete balls or gravel for example). Thus, the compressed gas directly exchanges (by direct contact) the heat it contains with the heat storage particles. This type of direct heat storage and recovery device is preferred for the “low pressure” compression stages, i.e. preferably the first stage of compression then successively preferably the second then the third and so on.

[0060] Preferably, when the system has at least three compression stages, the heat storage and recovery device may be a direct heat storage and recovery device comprising at least two first heat storage and recovery means, each of these first heat storage and recovery means comprising first heat storage particles.

[0061] Direct heat storage and recovery devices are generally simple to implement.

[0062] Furthermore, on at least one compression stage (preferably on the last compression stage, i.e. the compression stage just before the compressed gas storage means) in the direction of circulation of the compressed gas, the heat storage and recovery device is an indirect heat storage and recovery device comprising a cooling loop. The cooling loop comprises a non-direct contact (indirect contact) heat exchanger, also called heat exchange means, for exchanging heat between the compressed gas and a heat transfer fluid capable of circulating in the cooling loop.The cooling loop comprises a second heat storage and recovery means comprising second heat storage particles, the second heat storage and recovery means being configured to exchange heat directly between the second heat storage particles and the heat transfer fluid. As a result, the heat from the compressed gas is transferred by the heat exchanger without direct contact (a plate exchanger or a shell and tube exchanger for example) to the heat transfer fluid. Since the heat exchange takes place without direct contact between the compressed gas and the heat transfer fluid (by a plate or a tube), the pressure of the heat transfer fluid may be lower than that of the compressed gas.The heat transfer fluid circulates in the cooling loop so as to reach the second heat storage and recovery means where its heat is transmitted to the second heat storage particles. Thus, the heat transfer fluid leaves the second heat storage and recovery means colder than it entered and the heat is stored in the second heat storage particles. The advantage of this type of indirect heat storage and recovery device is that the internal pressure of the cooling loop and therefore of the second heat storage and recovery means is lower (much lower) than that which a heat storage and recovery means of a direct heat storage and recovery device would have, which is in fact at the pressure of the compressed gas. As a result, this second heat storage and recovery means. heat recovery system is lighter (the walls can be thinner) and its cost is reduced. In addition, the greater the pressure difference between the compressed gas in the stage concerned and the pressure of the heat transfer fluid, the greater the gain in mass and cost. Therefore, the use of an indirect heat storage and recovery device is advantageous for "high pressure" compression stages, therefore preferably the last compression stage, then the penultimate, then the antepenultimate and so on.

[0063] The combination of the use of direct heat storage and recovery devices for certain compression stages and indirect for other compression stages allows a reduction in the mass and cost of the system while maintaining an interesting efficiency for the system and the simplest possible system.

[0064] Preferably, the compression line may comprise as many compression stages as the expansion line comprises expansion stages, each heat storage and recovery device of a compression stage being used in the expansion stage at the corresponding pressure.

[0065] By "corresponding pressure" is meant not an absolute pressure but that of the stage concerned. In other words, the number of compression stages and the number of expansion stages can be identical. This embodiment allows a "symmetrical" design of the compression and expansion lines, with in particular similar operating pressures and temperatures, which promotes heat exchanges in the heat storage and recovery means. Thus, the system and the process are simplified.

[0066] For example, when the compression line and the expansion line each comprise three stages, the first compression stage is a so-called “low pressure” stage, the second compression stage is a so-called “medium pressure” stage, and the last stage is a so-called “high pressure” stage. The expansion line then comprises a first “high pressure” expansion stage, a second “medium pressure” expansion stage and a third “low pressure” expansion stage. The terminologies “high pressure”, “medium pressure” and “low pressure” are understood relatively between the different stages of the compression line and the expansion line. Thus, the heat storage and recovery device used for the third (“high pressure”) compression stage is used to reheat the compressed gas from the first (“high pressure”) expansion stage.The heat storage and recovery device used for the second compression stage ("medium pressure") is used to reheat the compressed gas from the second expansion stage ("medium pressure") and the heat storage and recovery device used for the first compression stage ("low pressure") is used to reheat the . compressed gas from the third expansion stage ("low pressure"). This configuration is advantageous because the pressure and temperature of each compression stage corresponds substantially to the pressure and temperature of each expansion stage, which further improves system performance.

[0067] Preferably, the expansion line and the compression line may each comprise three stages. This configuration makes it possible to improve compression and expansion performance while limiting cost.

[0068] Advantageously, at least one compression stage may comprise a first cooling means downstream of the heat storage and recovery device (in the direction of circulation of the compressed gas in the compression stage), whether direct or indirect. The first cooling means serves to further cool the compressed gas before it enters the next compression stage or the compressed gas storage means so as to further improve the compression of the gas in the next stage and / or to reduce the design constraints of the compressed gas storage means.

[0069] Preferably, the first cooling means may comprise an air cooler. An air cooler makes it possible to cool the compressed gas only with the ambient outside air. As a result, it is a cooling means that is simple to implement and inexpensive.

[0070] According to a variant, the cooling means may be a tube / shell, plate and / or spiral heat exchanger so as to exchange heat between the compressed gas and a fluid which may be water, propane, butane for example.

[0071] According to one embodiment of the invention, the cooling loop may comprise a second cooling means downstream of the second heat storage and recovery means (in the direction of circulation of the heat transfer fluid in the cooling loop), before the heat exchange means. The second cooling means serves to further cool the heat transfer fluid of the cooling loop after it has passed through the heat storage and recovery means comprising second heat storage particles and before it enters the heat exchange means, so as to reduce the temperature of the heat transfer fluid entering the heat exchange means, thereby making it possible to further improve the compression of the gas of the next stage and / or reduce the design constraints of the compressed gas storage means.

[0072] Preferably, the second cooling means may comprise an air cooler, for cooling the heat transfer fluid only with the ambient outside air. As a result, it is a cooling means that is simple to implement and inexpensive.

[0073] According to a variant, the second cooling means may be an exchanger of heat with tubes / shells, plates and / or spirals so as to exchange heat between the heat transfer fluid and another fluid which can be water, propane, butane for example.

[0074] According to an advantageous configuration of the invention, at least one compression stage (preferably each compression stage) may comprise a separation means (a gas / liquid separator for example) for separating the compressed gas from a liquid phase before the compressed gas reaches the next compression stage or the compressed gas storage means (in the case of the last compression stage), each compression stage comprising a separation means preferably comprising a liquid storage means for storing the liquid phase at the pressure of the compression stage. Indeed, when the heat of the compressed gas is recovered in the heat storage and recovery device or the compressed gas is cooled in the cooling means, the compressed gas is cooled and therefore, condensation can occur.This may be the case in particular when the gas is air taken from the ambient environment; it may then contain water vapor. This water vapor may then condense and the liquid phase produced is likely to cause damage in the compression stages or to the compressed gas storage means (for example, by corrosion). In addition, each compression stage may comprise a liquid storage means for storing the liquid phase at the pressure of the compression stage. Thus, each liquid phase recovered in each compression stage may be stored at the pressure of each compression stage, this phase being able to be injected into the expansion stage at the nearest corresponding pressure.

[0075] Advantageously, at least one expansion stage may comprise a mixing means (a mixer for example) for injecting and mixing with the compressed gas the liquid phase leaving one of the liquid storage means of the compression stages, the mixing means being positioned upstream of the heat storage and recovery device. Thus, a liquid phase which is vaporized can be injected into the heat storage and recovery device before each expansion means, whether this heat storage and recovery device is direct (with a heat storage and recovery means comprising heat storage particles) or indirect (with a cooling loop comprising a heat transfer fluid, a heat exchange means without direct contact and a heat storage and recovery means comprising heat storage particles).The addition of the liquid phase makes it possible to increase the gas flow rate at the inlet of the expansion means (of the turbine for example) and thus to improve its performance.

[0076] According to one implementation of the invention, the pipes of at least the first expansion stage can be configured to circulate the compressed gas in at least one indirect heat storage and recovery device and the pipes of at least one other expansion stage (preferably at least the last expansion stage) can be configured to circulate the compressed gas in at least one direct heat storage and recovery device. Indeed, the first expansion stage is the one with the highest pressure: its pressure therefore corresponds to the last compression stage (the one of the compression stages with the highest pressure). Thus, it is more advantageous to use the indirect heat storage and recovery device for this first expansion stage and subsequently preferentially for the second then the third and so on.

[0077] The invention also relates to a method for storing and recovering energy using compressed gas comprising at least the following steps:

[0078] - In the energy storage phase:

[0079] a) a gas is compressed at least once in a compression line comprising at least two compression stages, each compression stage comprising at least one compression means such as a compressor;

[0080] b) after each compression step, the heat is recovered from the compressed gas in at least one heat storage and recovery device; the heat storage and recovery device of at least one compression step (preferably the last compression step) with an indirect heat storage and recovery device thus implementing an indirect heat storage and recovery step with a cooling loop comprising a heat exchanger for exchanging heat between the compressed gas and a heat transfer fluid, and a (second) heat storage and recovery means comprising (second) heat storage particles for directly exchanging heat between the heat transfer fluid and the (second) heat storage particles,and the heat storage and recovery step of at least one further compression step with a direct heat storage and recovery device (comprising a first heat storage and recovery means comprising a fixed bed of first heat storage particles) for directly exchanging (by direct contact) heat between the compressed gas and the first storage particles. Thus, the heat storage and recovery step of at least one further compression step implements a direct heat storage and recovery step.

[0081] Indirect exchange makes it possible to use a cooling loop and a heat transfer fluid as described above and therefore to use a heat transfer fluid at a pressure lower than the pressure of the compressed gas. Direct exchange is simple to implement and is therefore preferred, for example, when the pressure of the compression stage is relatively low compared to the pressure of the heat transfer fluid (the pressure difference being of the order of 20 Bar for example) or that the gain in mass and / or cost of the system is low, for example less than 2%.

[0082] c) the cooled compressed gas is stored in at least one compressed gas storage means.

[0083] - In the energy recovery phase:

[0084] d) the compressed gas leaving the compressed gas storage means is circulated in an expansion line comprising at least two expansion stages, and in each expansion stage, the compressed gas is heated by circulating it in one of the heat storage and recovery devices (direct or indirect) using the heat stored during the compression stage and then the heated compressed gas is expanded in an expansion means. Heating the gas before it passes through the expansion means (a turbine for example) makes it possible to increase the performance of the system.

[0085] In other words, the method is suitable for implementing the system as described above.

[0086] Advantageously, as many compression steps as expansion steps can be carried out, and the heat storage and recovery device of each of steps b) can be used to reheat the compressed gas from the expansion step to the corresponding pressure. Thus, each heat storage and recovery device (direct or indirect) of a compression stage is particularly suitable for reheating an expansion stage (to the corresponding pressure). As a result, heat recovery in the expansion line is optimized.

[0087] Advantageously, the heat from the compressed gas can be recovered by (first and / or second) heat storage particles, preferably contained in the (first or second) heat storage and recovery means of the direct or indirect heat storage and recovery device. Thus, the heat stored in the storage particles can be easily reused during expansion to reheat the compressed gas in the expansion stages.

[0088] The heat storage particles can be concrete beads, gravel and / or phase change materials (possibly encapsulated). Concrete beads and gravel are simple and inexpensive solutions.

[0089] Preferably, after each heat recovery step, the compressed gas at the outlet of the heat storage and recovery device (direct or indirect) can be cooled in a first cooling means before the gas is sent to the next compression step or to the compressed gas storage means (for the last compression stage). Thus, the compressed gas can be better cooled before entering the next compression stage or the compressed gas storage means.

[0090] According to an implementation of the method of the invention, when the heat storage and recovery device is an indirect heat storage and recovery device (with a cooling loop as described in the system of the invention), the heat transfer fluid of the cooling loop can be cooled by a second cooling means positioned on the cooling loop after the heat storage and recovery means (upstream in the direction of circulation of the heat transfer fluid in the cooling loop), more precisely between the heat storage and recovery means and the heat exchanger without direct contact, in the direction of circulation of the heat transfer fluid in the cooling loop. As a result, the heat transfer fluid is better cooled before reaching the heat exchanger.

[0091] Advantageously, the compressed gas may be separated from a liquid phase it contains in a separation means, such as a separator, before the compressed gas is sent to the next compression stage or to the compressed gas storage means, the liquid leaving each separation means being stored at the pressure at which it is in a liquid storage means. Thus, the liquid that could condense during the cooling of the compressed gas by the heat storage and recovery device or by the first cooling means is separated from the gas phase, which makes it possible to limit the risk of damage to the components of the next compression stage (in particular the compression means) or the compressed gas storage means.

[0092] Preferably, in each expansion stage, the stored liquid from a liquid storage means can be injected, and it can be mixed with the compressed gas, before each reheating step. Thus, the flow rate of the gas passing through the expansion means is increased, which makes it possible to increase the performance of the expansion means. In addition, each liquid storage means being at a determined pressure and temperature, each expansion stage can advantageously use one of the liquid storage means of a compression stage (at the corresponding pressure).

[0093] Furthermore, as a result, liquid management in the system is optimized since the liquid leaving the compression phase is reintroduced into the expansion phase.

[0094] [Fig. 3] illustrates, in a schematic and non-limiting manner, a first embodiment of the system according to the invention.

[0095] In this figure, the elements and references identical to those of figures 1 and 2 correspond to the same elements and will not be detailed again.

[0096] [Fig. 3] differs from [Fig. 1] by the replacement of the heat storage and recovery device 202 of the last compression stage of [Fig. 1] by an indirect heat storage and recovery device comprising a cooling loop. The cooling loop comprises a heat exchanger 800 without direct contact allowing heat to be exchanged between the compressed gas and a heat transfer fluid contained in the cooling loop, a second heat storage and recovery means 203 comprising second heat storage particles forming a fixed bed and a second cooling means 303 (an air cooler) between the second heat storage and recovery means 203 and the heat exchanger 800 (in the direction of circulation of the heat transfer fluid in the cooling loop).

[0097] Furthermore, in this [Fig.3], on the last compression stage, there is no first cooling means (such as an air cooler) downstream of the indirect heat storage and recovery device (downstream of the heat exchanger 800).

[0098] The system of [Fig. 3] comprises two first heat storage and recovery means 200 and 201 each comprising first heat storage particles and which directly exchange heat between the first heat storage particles and the compressed gas.

[0099] The heat transfer fluid may in particular be SYLTHERM™ (Dow, USA) as is the case for the examples in Figures 3 to 6. However, other similar heat transfer fluids may be used in the system and the method according to the invention.

[0100] [Fig. 3] is also distinguished from [Fig. 1] on the expansion line where the heat storage and recovery device 202 of the first expansion stage of [Fig. 1] is replaced by the indirect heat storage and recovery device of the last compression stage. Thus, before reaching the first turbine 700 of the expansion line, the compressed gas passes through the heat exchanger without direct contact 800 where it is heated by the heat transfer fluid thanks to the second heat storage particles contained in the second heat storage and recovery means 203. When this cooling loop is used in the expansion stage, of course, the heat transfer fluid may not circulate in the first cooling means in order to recover a maximum of heat to heat the compressed gas.

[0101] [Fig.4] illustrates in a schematic and non-limiting manner a second embodiment of the invention.

[0102] In this figure, the elements and references identical to those of figures 1 to 3 correspond to the same elements and will not be detailed again.

[0103] Furthermore, this figure differs from [Fig.3] by the addition of liquid storage means 500, 501 and 502 at the outlet of each of the separation means, respectively 400, 401 and 402.

[0104] Furthermore, in order to optimize the liquid management within the system, the system comprises mixing means 600, 601 and 602 leaving each of the liquid storage means, respectively 500, 501 and 502 to reintroduce the liquid before the passage of the fluid in the expansion means 700, 701 and 702.

[0105] [Fig.5] illustrates, in a schematic and non-limiting manner, a third embodiment of the invention.

[0106] In this figure, the elements and references identical to those of figures 1 to 4 correspond to the same elements and will not be detailed again.

[0107] The system of this figure is distinguished from that of [Fig.3] by the removal of the second cooling means 303 on the cooling loop of the indirect heat storage and recovery device and by the addition of a first cooling means 302 downstream of the indirect heat storage and recovery device (downstream of the heat exchanger 800 and before the separation means 402 in the direction of circulation of the compressed gas in the compression line).

[0108] The system of [Fig.5] comprises two first heat storage and recovery means 200 and 201 each comprising first heat storage particles and which directly exchange heat between the first heat storage particles and the compressed gas.

[0109] [Fig.6] illustrates, in a schematic and non-limiting manner, a fourth embodiment of the invention.

[0110] In this figure, the elements and references identical to those of figures 1 to 5 correspond to the same elements and will not be detailed again.

[0111] The system of this figure is distinguished from that of [Fig.5] by the addition of liquid storage means 500, 501 and 502 at the outlet of each of the separation means, respectively 400, 401 and 402.

[0112] Furthermore, in order to optimize the liquid management within the system, the system comprises mixing means 600, 601 and 602 leaving each of the liquid storage means, respectively 500, 501 and 502 to reintroduce the liquid before the fluid passes into the expansion means 700, 701 and 702.

[0113] The system of [Fig.6] comprises two first heat storage and recovery means 200 and 201 each comprising first heat storage particles and which directly exchange heat between the first heat storage particles and the compressed gas.

[0114] In Figures 3 to 6, the compression line and the expansion line each advantageously comprise respectively three compression stages and three expansion stages but a different number of compression and / or expansion stages could be used.

[0115] Furthermore, in these figures, the first two compression stages comprise two first heat storage and recovery means 200 and 201 each comprising first heat storage particles and which directly exchange heat between the first heat storage particles and the compressed gas and the last compression stage comprises a cooling loop with a second heat storage and recovery means 203 each comprising second heat storage particles for exchanging heat between the second heat storage particles and a heat transfer fluid distinct (different) from the compressed gas. Of course, the system could comprise other first heat storage and recovery means and / or other cooling loops with other second heat storage and recovery means. Examples

[0116] The systems of Figures 3 to 6 of the invention were compared to the prior art systems illustrated in Figures 1 and 2. More specifically, the systems of the invention corresponding to Figures 3 and 5 are compared to the prior art of [Fig.l]: all these systems do not reuse the liquid recovered at the outlet of the separation means, for the expansion phase. The systems of the invention corresponding to Figures 4 and 6 are compared to the prior art of [Fig.2]: all these systems reuse the liquid recovered at the outlet of the separation means for the expansion phase.

[0117] For the embodiments of Figures 3 to 6 comprising a cooling loop on the compression stage at the highest pressure, the heat transfer fluid circulating in the cooling loop is SYLTHERM™.

[0118] The prior art system of [Fig.l] operates for example in the following manner.

[0119] During the compression phase 1, an external air flow 10, at atmospheric pressure and a temperature of 27°C and having a humidity of 14.6 grams of water per kilogram of air, is compressed by a low-pressure compressor 100 from which it exits 11 at a temperature of 255°C and a pressure of 6 bar (0.6 MPa). This flow 11 is sent to a low-pressure direct heat storage and recovery device 200 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device 200 cooling the air to a temperature of 90°C and storing this thermal energy in the heat storage particles until the expansion phase 2. The flow 12 is cooled once again by the cooling means 300 until it reaches a temperature of 50°C at the outlet.The flow 13 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 200 and / or in the cooling means 300. This condensed water 14 is separated from the compression line 2 in a gas-liquid separator 400 operating at the pressure of the flow. The gas flow 15 leaving the gas / liquid separator 400, again completely . gaseous, is compressed by a medium pressure compressor 101 from which it emerges 16 at a temperature of 275°C and a pressure of 28 bar. The flow 16 is sent to a medium pressure direct heat storage and recovery device 201 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device 201 cooling the air to a temperature of 100°C and storing this thermal energy in the heat storage particles until the expansion phase 2. The flow 17 leaving the direct heat storage and recovery device 201 is cooled once again by a cooling means 301 until it reaches a temperature of 50°C at the outlet.The flow 18 leaving the cooling means 301 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 201 and / or in the cooling means 301. This condensed water 19 is separated from the compression line 1 in a gas-liquid separator 401 operating at the pressure of the flow. The flow 20, again completely gaseous, leaving the gas / liquid separator 401 is compressed by a high-pressure compressor 102 from which it emerges at a temperature of 250°C and a pressure of 117 bar.The flow 21 is sent to a high-pressure direct heat storage and recovery device 202 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device 202 cooling the air to a temperature of 45°C and storing this thermal energy in the heat storage particles until the expansion phase 2. The flow 22 leaving the direct heat storage and recovery device 202 is cooled once again by a cooling means 302 until it reaches a temperature of 30°C at the outlet, 30°C being the storage temperature of the air. The flow 23 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 202 and / or in the cooling means 302.This condensed water 24 is separated from the compression line 1 in a gas-liquid separator 402 operating at the pressure of the flow 23.

[0120] The flow 25 of compressed air at a pressure of 117 bar and a temperature of 30°C is then sent to the compressed air storage means 1000 while waiting for the energy recovery phase 2.

[0121] When electricity is to be produced, the compressed air flow 26 at a pressure of 117 bar and a temperature of 30°C, leaving the compressed air storage means 1000 is heated in the high-pressure direct heat storage and recovery device 202 which releases the heat stored in the heat storage particles during the compression phase until the flow 27 reaches a temperature temperature of 240°C. This flow of hot and compressed air 27 is expanded in the high-pressure turbine 700 producing electricity via an alternator, until it reaches at the outlet 28 a pressure of 28 bar and a temperature of 85°C. The flow 28 is reheated in the medium-pressure direct heat storage and recovery device 201 which releases the heat stored in the heat storage particles during the compression phase until the flow 29 reaches a temperature of 265°C. This flow of hot and compressed air 29 is expanded in the medium-pressure turbine 701 producing electricity via an alternator, until it reaches at the outlet 30 a pressure of 5 bar and a temperature of 75°C.The flow 30 is reheated in the low-pressure direct heat storage and recovery device 200 which releases the heat stored in the heat storage particles during the compression phase until the flow 31 reaches a temperature of 245°C. This flow of hot and compressed air 31 is expanded in the low-pressure turbine 702 producing electricity via an alternator, until it reaches at the outlet 32 ​​a pressure of 1.02 bar and a temperature of 80°C.

[0122] The efficiency of the energy storage method of the example of [Fig. 1] of the prior art is 69.6% for a power consumption of 100 MW at the compressors. The total flow rate of condensed water at the three compression stages is 7.5 t / h. The thermal storage power is 87 MW and the necessary cooling power is 20.5 MW.

[0123] The system of [Fig. 3] operates for example in the following manner. During the compression phase 1, an external air flow 10, at atmospheric pressure and a temperature of 27°C and having a humidity of 14.6 grams of water per kilogram of air, is compressed by a low pressure compressor 100 from which it emerges 11 at a temperature of 255°C and a pressure of 6 bar. This flow 11 is sent to a low-pressure direct heat storage and recovery device 200 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device 200 cooling the air to a temperature of 90°C and storing this thermal energy in the heat storage particles until the expansion phase 2. The flow 12 is cooled once again by a cooling means 300 until it reaches a temperature of 50°C at the outlet.The flow 13 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 200 and / or in the cooling means 300. This condensed water 14 is separated from the flow of the compression line 1 in a gas-liquid separator 400, operating at the pressure of the flow 13. The flow 15, again completely gaseous, is compressed by a medium pressure compressor 101 from which it emerges at a temperature of 275°C and a . pressure of 28 bar. The flow 16 is sent to a medium-pressure direct heat storage and recovery device 201 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device 201 cooling the air to a temperature of 93°C and storing this thermal energy in the storage particles until the expansion phase 2. The flow 17 is cooled once again by a cooling means 301 until it reaches a temperature of 50°C at the outlet 18. The flow 18 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 201 and / or in the cooling means 301. This condensed water 19 is separated from the flow of the compression line 1 in a gas-liquid separator 401, operating at the pressure of the flow 18.The flow 20, again completely gaseous, is compressed by a high-pressure compressor 102 from which it emerges at a temperature of 250°C and a pressure of 117 bar. The flow 21 is sent to an indirect contact heat exchanger 800 allowing the exchange of heat between the hot air flow 21 and a low-pressure (6 bar) heat transfer fluid flow (3'). The flow 21 is cooled until it reaches a temperature of 55°C at the outlet 22. The heat transfer fluid is heated by heat exchange until it reaches a temperature of 245°C at the outlet of the indirect contact heat exchanger 800.This flow 1' is then sent to a low-pressure direct heat storage and recovery means 203 comprising second heat storage particles directly exchanging heat with the heat transfer fluid, the heat storage and recovery means 203 cooling the heat transfer fluid to a temperature of 65°C and storing this thermal energy in the second heat storage particles until the expansion phase 2. The flow 2' of heat transfer fluid is cooled once again by a cooling means 303 until it reaches a temperature of 50°C at the outlet 3' and thus creates a cooling loop between the low-pressure direct heat storage and recovery means 203 and the heat exchanger without direct contact 800, this assembly forming an indirect heat storage and recovery device.The flow 22 leaving this indirect heat storage and recovery device is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phase in the heat exchanger 800. This condensed water is separated from the flow of the compression line 1 in a gas-liquid separator 402, operating at the pressure of the flow 22.

[0124] The flow of compressed air at a pressure of 117 bar and a temperature of 55°C leaving the gas-liquid separator 402 is then sent to the compressed air storage means 1000 while waiting for the energy recovery phase 2.

[0125] In addition, it is considered that the temperature of the air stored in the storage means compressed air 1000 drops by 10°C during the interval between the compression and expansion phases.

[0126] When electricity is to be produced, the compressed air flow at a pressure of 117 bar and a temperature of 45°C, leaving the compressed air storage means 1000 is heated by heat exchange with the flow 4' of low-pressure heat transfer fluid in the heat exchanger without direct contact 800 until the flow reaches a temperature of 230°C. The flow 4' is preheated in the low-pressure heat storage and recovery means 203 which releases the heat stored in the second heat storage particles during the compression phase until the flow 4' reaches a temperature of 235°C.The heat transfer fluid flow is cooled to a temperature of 50°C at the outlet (5') of the heat exchanger 800 and returned to the low pressure heat storage and recovery means 203 to perform a reheating loop between the low pressure heat storage and recovery means 203 and the heat exchanger without direct contact 800. The hot and compressed air flow is expanded in the high pressure turbine 700 producing electricity via an alternator, until it reaches a pressure of 28 bar and a temperature of 80°C at the outlet. The flow is then reheated in the medium pressure direct heat storage and recovery device 201 which releases the heat stored in the first heat storage particles during the compression phase until the flow reaches a temperature of 265°C.This hot and compressed air flow is expanded in the medium pressure turbine 701 producing electricity via an alternator, until it reaches an outlet pressure of 5 bar and a temperature of 75°C. The flow is reheated in the low pressure direct heat storage and recovery device 200 which releases the heat stored in the first heat storage particles during the compression phase until the flow reaches a temperature of 245°C. This hot and compressed air flow is expanded in the low pressure turbine 702 producing electricity via an alternator, until it reaches an outlet pressure of 1.02 bar and a temperature of 80°C.

[0127] The efficiency of the energy storage process is 69.3% for a power consumption of 100 MW at the compressors. The total flow rate of condensed water at the three compression stages is 7.5 t / h. The thermal storage power is 84.5 MW and the required cooling power is 16.8 MW. Thus, the performance is close to that of the system in [Fig.l] with a lower required cooling power (which implies less energy consumption).

[0128] The integration of the cooling loop (or reheating in the expansion phase) of heat transfer fluid associated with the heat exchanger and the means of storage and recovery of direct low pressure heat on the high pressure stage makes it possible to reduce the cost of the heat storage and recovery means 203 by 79% compared to the heat storage and recovery means 202 of the example in [Fig.l]. In addition, the installation of the indirect heat storage and recovery device (heat exchanger, low-pressure heat storage and recovery means and heat transfer fluid) allows a cost reduction of 11% compared to the direct high-pressure heat storage and recovery means (consisting of the heat storage and recovery means 202) of the example in [Fig.l].

[0129] The system of [Fig.5] operates for example in the following manner.

[0130] The first two compression stages 3, low and medium pressure, are similar to those of the example in [Fig.3].

[0131] The distinction between the system of Figures 3 and 5 occurs at the high-pressure compression stage following the compression of the air flow 20 by a high-pressure compressor 102 from which it emerges at a temperature of 250°C and a pressure of 117 bar. The flow 21 is sent to a heat exchanger without direct contact 800 allowing the exchange of heat between the hot air flow 21 and a low-pressure heat transfer fluid flow 2”. The flow 21 is cooled until it reaches a temperature of 50°C at the outlet 22. The heat transfer fluid is heated by heat exchange until it reaches a temperature of 245°C at the outlet.This flow 1” is then sent to a low-pressure direct heat storage and recovery means 203 comprising second heat storage particles, the heat storage and recovery means 203 cooling the heat transfer fluid to a temperature of 50°C and storing this thermal energy in the second heat storage particles until the expansion phase 2, thus performing a cooling loop between the low-pressure direct heat storage and recovery means 203 and the heat exchanger without direct contact 800. The flow 22 is cooled once again by a cooling means 302 until it reaches a temperature of 30°C at the outlet, 30°C being the storage temperature of the air. The flow 23 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the heat exchanger 800 and / or in the cooling means 302.This condensed water 24 is separated from the flow of the compression line 1 in a gas-liquid separator 402, operating at the pressure of the flow 23.

[0132] The compressed air flow 25 at a pressure of 117 bar and a temperature of 30°C is then sent to the compressed air storage means 1000 while waiting for the energy recovery phase 2.

[0133] When electricity is to be produced, the flow of compressed air 26 at a pressure of 117 bar and a temperature of 30°C, leaving the compressed air storage means 1000 is heated by heat exchange with the flow 3” of low heat transfer fluid pressure in the heat exchanger without direct contact 800 until the flow 27 reaches the temperature of 230°C. The flow 3” is preheated in the low pressure direct heat storage and recovery means 203 which releases the heat stored in the second heat storage particles during the compression phase until the flow 3” reaches a temperature of 235°C. The heat transfer fluid flow 4” is cooled to a temperature of 35°C at the outlet of the heat exchanger 800 and returned to the low pressure heat storage and recovery means 203 to perform a reheating loop between the low pressure heat storage and recovery means 203 and the heat exchanger without direct contact 800.The hot and compressed air flow 27 is expanded in the high-pressure turbine 700 producing electricity via an alternator, until it reaches an outlet pressure of 28 bar and a temperature of 80°C. The flow 28 is reheated in the medium-pressure direct heat storage and recovery device 201 which releases the heat stored in the first heat storage particles during the compression phase until the flow 29 reaches a temperature of 265°C. This hot and compressed air flow 29 is expanded in the medium-pressure turbine 701 producing electricity via an alternator, until it reaches an outlet pressure of 5 bar and a temperature of 75°C.The flow 30 is reheated in the low-pressure direct heat storage and recovery device 200 which releases the heat stored in the first heat storage particles during the compression phase until the flow 31 reaches a temperature of 245°C. This flow of hot and compressed air 31 is expanded in the low-pressure turbine 702 producing electricity via an alternator, until it reaches at the outlet 32 ​​a pressure of 1.02 bar and a temperature of 80°C.

[0134] The efficiency of the energy storage process is 69.2% for a power consumption of 100 MW at the compressors. The total flow rate of condensed water at the three compression stages is 7.6 t / h. The thermal storage power is 87 MW and the required cooling power is 21 MW. Thus, this system has performances close to that of [Fig. 1].

[0135] The integration of the heat transfer fluid loop associated with the heat exchanger and the low pressure heat storage and recovery means on the high pressure stage makes it possible to reduce the cost of the heat storage and recovery means 203 by 79% compared to that 202 of [Fig.l].

[0136] The prior art system of [Fig.2] operates for example in the following manner.

[0137] During the compression phase 1, an external air flow 10, at a pressure of 1.02 bar and a temperature of 27°C and having a humidity of 14.6 grams of water per kilogram of air, is compressed by a low pressure compressor 100 from which it exits at a temperature of 255°C and a pressure of 6 bar. This flow 11 is sent to a low-pressure direct heat storage and recovery device 200 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device cooling the air to a temperature of 80°C and storing this thermal energy in the first storage particles until the expansion phase 2. The flow 12 is cooled once again by a cooling means 300 until it reaches a temperature of 50°C at the outlet. The flow 13 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 200 and / or in the cooling means 300.This condensed water 14 is separated from the flow of the compression line 1 in a gas-liquid separator 400, operating at the pressure of the flow 13, then sent to a liquid storage means 500 under a maintained pressure of 6 bar. The flow 15, again completely gaseous, is compressed by a medium pressure compressor 101 from which it emerges at a temperature of 275°C and a pressure of 28 bar. The flow 16 is sent to a medium pressure direct heat storage and recovery device 201 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device 201 cooling the air to a temperature of 80°C and storing this thermal energy in the first heat storage particles until the expansion phase 2. The flow 17 is cooled once again by a cooling means 301 until it reaches a temperature of 50°C at the outlet.The flow 18 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 201 and / or in the cooling means 301. This condensed water 19 is separated from the flow of the compression line 1 in a gas-liquid separator 401, operating at the pressure of the flow 18, then sent to a liquid storage means 501 under a maintained pressure of 28 bar. The flow 20, again completely gaseous, is compressed by a high-pressure compressor 102 from which it emerges at a temperature of 250°C and a pressure of 117 bar.The stream 21 is sent to a high-pressure direct heat storage and recovery device 202 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device 202 cooling the air to a temperature of 40°C and storing this thermal energy in the first heat storage particles until the expansion phase 2. The stream 22 is cooled once again by a cooling means 302 until it reaches a temperature of 30°C at the outlet, 30°C being the storage temperature of the air. The stream 23 is then composed of air and water, from . the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 202 and / or in the cooling means 302. This condensed water 24 is separated from the flow of the compression line 1 in a gas-liquid separator 402, operating at the pressure of the flow 23, then sent to a liquid storage means 502 under a maintained pressure of 117 bar.

[0138] The compressed air flow 25 at a pressure of 117 bar and a temperature of 30°C is then sent to the compressed air storage means 1000 while waiting for the energy recovery phase 2.

[0139] When electricity is to be produced, a flow of condensed water from the liquid storage means 502 at a pressure of 117 bar and a temperature of 30°C is reinjected into the flow of compressed air 26 leaving the compressed air storage means 1000 via the mixer 600. The flow thus formed is reheated in the high-pressure direct heat storage and recovery device 202 which releases the heat stored in the first heat storage particles during the compression phase until the flow reaches a temperature of 240°C. This flow of hot and compressed air is expanded in the high-pressure turbine 700 producing electricity via an alternator, until it reaches a pressure of 28 bar and a temperature of 85°C at the outlet.A flow of condensed water from the liquid storage means 501 at a pressure of 28 bar and a temperature of 50°C is reinjected into the compressed air flow exiting the high-pressure turbine 700 via the mixer 601. The flow thus formed is reheated in the medium-pressure direct heat storage and recovery device 201 which releases the heat stored in the first heat storage particles during the compression phase until the flow reaches a temperature of 255°C. This flow of hot and compressed air is expanded in the medium-pressure turbine 701 producing electricity via an alternator, until it reaches a pressure of 5 bar and a temperature of 70°C at the outlet. A flow of condensed water from the liquid storage means 500 at a pressure of 6 bar and a temperature of 50°C is reinjected into the flow of compressed air leaving the medium pressure turbine 701 via the mixer 602.The flow thus formed is heated in the low pressure direct heat storage and recovery device 200 which releases the heat stored in the first heat storage particles during the compression phase until the flow reaches a temperature of 245°C. This flow of hot and compressed air is expanded in the low pressure turbine 702 producing electricity via an alternator, until it reaches an outlet pressure of 1.02 bar and a temperature of 80°C.

[0140] The efficiency of the energy storage process is 70.4% for a power consumption of 100 MW at the compressors. The total flow rate of condensed water at the three compression stages is 7.5 t / h. The thermal storage power is 93 MW and the required cooling power is 14.6 MW.

[0141] The system of [Fig.4] operates for example in the following manner.

[0142] During the compression phase 1, an external air flow 10, at a pressure of 1.02 bar and a temperature of 27°C and having a humidity of 14.6 grams of water per kilogram of air, is compressed by a low-pressure compressor 100 from which it exits at a temperature of 255°C and a pressure of 6 bar. This flow 11 is sent to a low-pressure direct heat storage and recovery device 200 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device 200 cooling the air to a temperature of 80°C and storing this thermal energy in the first heat storage particles until the expansion phase 2. The flow 12 is cooled once again by a cooling means 300 until it reaches a temperature of 50°C at the outlet.The flow 13 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 200 and / or in the cooling means 300. This condensed water 14 is separated from the flow of the compression line 1 in a gas-liquid separator 400, operating at the pressure of the flow 13, then sent to a liquid storage means 500 under a maintained pressure of 6 bar. The flow 15, again completely gaseous, is compressed by a medium-pressure compressor 101 from which it emerges at a temperature of 275°C and a pressure of 28 bar.The flow 16 is sent to a medium-pressure direct heat storage and recovery device 201 comprising first heat storage particles directly exchanging heat with the compressed gas, the heat storage and recovery device 201 cooling the air to a temperature of 80°C and storing this thermal energy in the first storage particles until the expansion phase 2. The flow 17 is cooled once again by a cooling means 301 until it reaches a temperature of 50°C at the outlet. The flow 18 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the direct heat storage and recovery device 201 and / or in the cooling means 301.This condensed water 19 is separated from the flow of the compression line 1 in a gas-liquid separator 401, operating at the pressure of the flow 18, then sent to a liquid storage means 501 under a maintained pressure of 28 bar. The flow 20, again completely gaseous, is compressed by a high-pressure compressor 102 from which it emerges at a temperature of 250°C and a pressure of 117 bar. The flow 21 is sent to an indirect contact heat exchanger 800 allowing the exchange of heat between the flow of hot air 21 and a flow of low-pressure heat transfer fluid 3'. The flow 21 is cooled until it reaches a temperature of 55°C in . outlet of the indirect contact heat exchanger 800. The heat transfer fluid heats up by heat exchange until it reaches a temperature of 245°C in 1'. This flow 1' is then sent to a low-pressure heat storage and recovery means 203 comprising second heat storage particles directly exchanging heat with the heat transfer fluid, the heat storage and recovery means 203 cooling the heat transfer fluid to a temperature of 60°C and storing this thermal energy in the second heat storage particles until the expansion phase 2.The flow 2' of heat transfer fluid is cooled once again by a second cooling means 303 until it reaches a temperature of 50°C at the outlet 3' and thus creates a cooling loop between the low-pressure heat storage and recovery means 203 and the indirect contact heat exchanger 800, thus forming an indirect heat storage and recovery device. The flow 22 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phase in the heat exchanger 800. This condensed water is separated from the flow of the compression line 1 in a gas-liquid separator 402, operating at the pressure of the flow 22, then sent to a liquid storage means 502 under a maintained pressure of 117 bar.

[0143] The flow of compressed air at a pressure of 117 bar and a temperature of 55°C is then sent to the compressed air storage means 1000 while waiting for the energy recovery phase 2. It is considered that the temperature of the air stored in the storage means 1000 drops by 10°C during the interval between the compression and expansion phases.

[0144] When electricity is to be produced, a flow of condensed water from the liquid storage means 502 at a pressure of 117 bar and a temperature of 55°C is reinjected into the flow of compressed air leaving the compressed air storage means 1000 via the mixer 600. The flow thus formed is heated by heat exchange with the flow 4' of low-pressure heat transfer fluid in the indirect contact heat exchanger 800 until the flow reaches a temperature of 230°C. The flow 4' is preheated in the low-pressure heat storage and recovery means 203 which releases the heat stored in the second heat storage particles during the compression phase until the flow 4' reaches a temperature of 235°C.The flow of heat transfer fluid is cooled to a temperature of 50°C at the outlet 5' of the heat exchanger 800 and returned to the low pressure heat storage and recovery means 203 to perform a reheating loop between the low pressure heat storage and recovery means 203 and the indirect contact heat exchanger 800. This flow of hot and compressed air is expanded in the high pressure turbine 700 producing . electricity via an alternator, until reaching at the outlet a pressure of 28 bar and a temperature of 75°C. A flow of condensed water from the liquid storage means 501 at a pressure of 28 bar and a temperature of 50°C is reinjected into the compressed air flow via the mixer 601. The flow is reheated in the medium pressure direct heat storage and recovery device 201 which releases the heat stored in the first heat storage particles during the compression phase until the flow reaches a temperature of 255°C. This flow of hot and compressed air is expanded in the medium pressure turbine 701 producing electricity via an alternator, until reaching at the outlet a pressure of 5 bar and a temperature of 70°C. A flow of condensed water from the liquid storage means 500 at a pressure of 6 bar and a temperature of 50°C is reinjected into the compressed air flow via the mixer 602.The flow thus formed is heated in the low-pressure direct heat storage and recovery device 200 which releases the heat stored in the first storage particles during the compression phase until the flow reaches a temperature of 245°C. This flow of hot and compressed air is expanded in the low-pressure turbine 702 producing electricity via an alternator, until it reaches an outlet pressure of 1.02 bar and a temperature of 85°C.

[0145] The efficiency of the energy storage process is 69.9% for a power consumption of 100 MW at the compressors. The total flow rate of condensed water at the three compression stages is 7.5 t / h. The thermal storage power is 90.5 MW and the required cooling power is 11.5 MW. The required cooling power is therefore reduced by 3.1 MW compared to the system of [Fig.2] of the prior art.

[0146] The integration of the cooling loop (or reheating in the expansion phase) of the heat transfer fluid associated with the heat exchanger and the low pressure heat storage and recovery means on the high pressure stage makes it possible to reduce the cost of the heat storage and recovery means 203 by 79% compared to the heat storage and recovery means 202 of [Fig. 2]. In addition, the installation of the indirect heat storage and recovery device (comprising the heat exchanger without direct contact, the low pressure heat storage and recovery means and the heat transfer fluid) allows a cost reduction of 9% compared to the average heat storage and recovery device (consisting of the heat storage and recovery means 202) of the system of [Fig. 2].

[0147] The system of [Fig.6] operates for example in the following manner:

[0148] The first two compression stages 3, low and medium pressure, are similar to those of the system in [Fig.4].

[0149] The distinction between the systems of figures 4 and 6 occurs at the level of the high pressure compression stage following the compression of the air flow 20 by a high pressure compressor 102 from which it emerges 21 at a temperature of 250°C and a pressure of 117 bar.

[0150] The flow 21 is sent to an indirect contact heat exchanger 800 allowing the exchange of heat between the hot air flow 21 and a low pressure heat transfer fluid flow 2''. The flow 21 is cooled until it reaches a temperature of 50°C at the outlet of the indirect contact heat exchanger 800. The heat transfer fluid is heated by heat exchange until it reaches a temperature of 245°C in 1”. This flow 1'' is then sent to a low pressure heat storage and recovery means 203 comprising second heat storage particles directly exchanging heat with the heat transfer fluid, the heat storage and recovery means 203 cooling the heat transfer fluid to a temperature of 50°C and storing this thermal energy in the second storage particles until the expansion phase 2.The heat transfer fluid thus forms a cooling loop between the low-pressure heat storage and recovery means 203 and the indirect contact heat exchanger 800. The flow 22 is cooled once again by a cooling means 302 until it reaches a temperature of 30°C at the outlet, 30°C being the air storage temperature. The flow 23 is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in the heat exchanger without direct contact 800 and / or in the cooling means 302. This condensed water 24 is separated from the flow of the compression line 1 in a gas-liquid separator 402, operating at the pressure of the flow 23, then sent to a liquid storage means 502 under a maintained pressure of 117 bar.

[0151] The compressed air flow 25 at a pressure of 117 bar and a temperature of 30°C is then sent to the compressed air storage means 1000 while waiting for the energy recovery phase 2.

[0152] When electricity is to be produced, a flow of condensed water coming from the liquid storage means 502 at a pressure of 117 bar and a temperature of 30°C is reinjected into the flow of compressed air 26 leaving the compressed air storage means 1000 via the mixer 600.

[0153] The flow thus formed is heated by heat exchange with the 3” flow of low-pressure heat transfer fluid in the indirect contact exchanger 800 until the flow reaches a temperature of 230°C. The 3” flow is preheated in the low-pressure heat storage and recovery means 203 which releases the heat stored in the second heat storage particles during the compression phase until the 3” flow reaches a temperature of 235°C. The flow of heat transfer fluid is cooled to a temperature of 35°C at the 4” outlet of the indirect contact heat exchanger 800 and returned to the low pressure heat storage and recovery means 203 to perform a reheating loop between the low pressure heat storage and recovery means 203 and the indirect contact heat exchanger 800. The hot and compressed air flow is expanded in the high pressure turbine 700 producing electricity via an alternator, until it reaches a pressure of 28 bar and a temperature of 80°C at the outlet. A flow of condensed water from the liquid storage means 501 at a pressure of 28 bar and a temperature of 50°C is reinjected into the compressed air flow via the mixer 601.The flow thus formed is heated in the medium-pressure direct heat storage and recovery device 201 which releases the heat stored in the first storage particles during the compression phase until the flow reaches a temperature of 255°C. This hot and compressed air flow is expanded in the medium-pressure turbine 701 producing electricity via an alternator, until it reaches an outlet pressure of 5 bar and a temperature of 70°C. A flow of condensed water from the liquid storage means 500 at a pressure of 6 bar and a temperature of 50°C is reinjected into the compressed air flow via the mixer 602. The flow thus formed is heated in the low-pressure direct heat storage and recovery device 200 which releases the heat stored in the first heat storage particles during the compression phase until the flow reaches a temperature of 245°C.This flow of hot, compressed air is expanded in the low-pressure turbine 702, producing electricity via an alternator, until it reaches a pressure of 1.02 bar and a temperature of 85°C at the outlet.

[0154] The efficiency of the energy storage process is 69.7% for a power consumption of 100 MW at the compressors. The total flow rate of condensed water at the three compression stages is 7.6 t / h. The thermal storage power is 93 MW and the required cooling power is 15 MW.

[0155] The integration of the heat transfer fluid loop associated with the heat exchanger and the low pressure heat storage and recovery means 203 on the high pressure stage makes it possible to reduce the cost of the heat storage and recovery means 203 by 79% compared to the heat storage and recovery means 202 of [Fig.2].

Claims

Claims

1. Compressed gas energy storage and recovery system comprising: - a gas compression line (1) with at least two compression stages (3), each compression stage (3) comprising a compression means (100, 101, 102) and a heat storage and recovery device positioned downstream of the compression means (100, 101, 102), in the direction of circulation of the compressed gas in the compression stage, - at least one compressed gas storage means (1000) located at the outlet of the gas compression line (1) for storing the compressed gas, - an expansion line (2) for expanding compressed gas stored in the compressed gas storage means (1000), the expansion line (2) comprising at least two successive expansion stages (4), each expansion stage (4) comprising pipes and an expansion means (700, 701, 702), the pipes of each expansion stage being configured to circulate the compressed gas in at least one device for storing and recovering the heat of the compression stages (3) so as to heat the compressed gas before the expansion means (700, 701, 702), characterized in that: - on at least one of the compression stages (3), the heat storage and recovery device is a direct heat storage and recovery device comprising at least a first heat storage and recovery means (200, 201) comprising first heat storage particles, the first heat storage and recovery means (200, 201) being configured to exchange heat directly between the compressed gas and the first heat storage particles, - on at least the last compression stage (3), in the direction of circulation of the compressed gas, the heat storage and recovery device is an indirect heat storage and recovery device comprising a cooling loop,the cooling loop comprising a heat exchanger (800) without direct contact for exchanging heat between the compressed gas and a heat transfer fluid capable of circulating in the cooling loop, the loop of, cooling comprising a second heat storage and recovery means (203) comprising second heat storage particles, the second heat storage and recovery means being configured to exchange heat directly between the second storage particles and the heat transfer fluid and - each compression stage comprises separation means for separating the compressed gas from a liquid phase before the compressed gas reaches the next compression stage or the compressed gas storage means.

2. System according to claim 1, wherein said compression line (1) comprises as many compression stages (3) as the expansion line (2) comprises expansion stages (4), each heat storage and recovery device of a compression stage being used in the expansion stage at the corresponding pressure, preferably the expansion line (1) and the compression line (2) each comprise three stages.

3. System according to one of the preceding claims, for which at least one compression stage comprises a first cooling means (300, 301, 302) downstream of the heat storage and recovery device, preferably, said cooling means (300, 301, 302) comprising an air cooler.

4. System according to one of the preceding claims, for which the cooling loop comprises a second cooling means (303) downstream, in the direction of flow during the loading of the system, of the second heat storage and recovery means (203), preferably, said second cooling means (303) comprising an air cooler.

5. System according to one of the preceding claims, for which each compression stage (3) comprises a liquid storage means (500, 501, 502) for storing said liquid phase at the pressure of the compression stage (3).

6. System according to claim 5, for which at least one expansion stage (4) comprises a mixing means (600, 601, 602) for mixing said compressed gas with said liquid phase leaving one of the liquid storage means (500, 501, 502) of the compression stages (3), the mixing means (600, 601, 602) being positioned upstream of said heat storage and recovery device.

7. System according to one of the preceding claims, for which the pipes of at least the first expansion stage are configured to circulate the compressed gas in at least one indirect heat storage and recovery device and for which the pipes of at least one other expansion stage are configured to circulate the compressed gas in at least one direct heat storage and recovery device.

8. Method for storing and recovering energy by compressed gas comprising at least the following steps: - In the energy storage phase: a) a gas is compressed at least once in a compression line (1) comprising at least two compression stages (4), each compression stage (4) comprising at least one compression means (100, 101, 102) and the compressed gas is separated from a liquid phase which it contains in a separation means (400, 401, 402), before the compressed gas is sent to the next compression stage (3) or to the compressed gas storage means; b) after each compression step (4),the heat of said compressed gas is recovered in at least one heat storage and recovery device; the heat storage and recovery step of at least the last compression step (3) implementing an indirect heat storage and recovery step with a cooling loop comprising a heat exchanger (800) for exchanging heat between the compressed gas and a heat transfer fluid and a second heat storage and recovery means (203) comprising second storage particles,and the step of storing and recovering the heat of at least one other compression step implementing a direct heat storage and recovery step. c) storing the cooled compressed gas in at least one compressed gas storage means (1000). - In the energy recovery phase: d) circulating the compressed gas leaving the compressed gas storage means (1000) in an expansion line (2) of at least two expansion steps (4), and in each expansion step (4), heating the compressed gas by circulating it in one of the heat storage and recovery devices using the heat stored during the compression step (3) and then expanding the heated compressed gas in a, means of relaxation (700, 701, 702).

9. Method according to claim 8, for which as many compression steps as expansion steps are carried out, and the heat storage and recovery device of each of steps b) is used to reheat the compressed gas from the expansion step to the corresponding pressure.

10. Method according to one of claims 8 or 9, for which the heat from the compressed gas is recovered by heat storage particles.

11. Method according to one of claims 8 to 10, for which, after each heat recovery step, the compressed gas is cooled at the outlet of the heat storage and recovery device in a first cooling means (300, 301, 302) before the gas is sent to the following compression step or to the compressed gas storage means (1000).

12. Method according to one of claims 8 to 11, for which, when the heat storage and recovery device is an indirect heat storage and recovery device, the heat transfer fluid of the cooling loop is cooled by a second cooling means positioned on the cooling loop after the second heat storage and recovery means.

13. Method according to one of claims 8 to 12, for which the liquid leaving each separation means (400, 401, 402) is stored or discharged at the pressure in which it is in a liquid storage means (500, 501, 502).

14. A method according to claim 13, wherein, in each expansion stage, the stored liquid is injected from a liquid storage means (500, 501, 502), and preferably, it is mixed with the compressed gas, before each reheating step.

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