System and method for storing and recovering energy with compressed gas with liquid recovery

Abstract

The invention relates to a system and method for storing and recovering energy by means of compressed gas, comprising a compression line (1), an air storage device (1000) and an expansion line (2). According to the invention, the compression line (1) and the expansion line (2) comprise a thermal storage device (200, 201, 202) comprising thermal storage particles. Furthermore, the expansion line comprises a device for injecting and mixing a liquid (600, 601, 602) in the expansion line (2).

Description

Technical Field

[0001] This invention relates to the field of storing and producing energy through the compression and expansion of gases, particularly air. Background Technology

[0002] While global energy goals aim to promote the replacement of fossil fuels with renewable energy and gradually increase the proportion of renewable energy in the energy mix, their variability remains a major drawback. Energy storage appears to be an ideal solution to this problem. By storing excess electricity generated during peak production (peak power generation) for use when production is below demand, storage circumvents the constraints of variability and provides renewable energy with a continuity, or at least flexibility, that was not initially present. Therefore, energy storage methods are needed, and these methods will increase as the proportion of such energy in the global energy mix grows.

[0003] Many mature energy storage technologies already exist, such as mechanical energy storage, like pumped-storage hydroelectric power stations that utilize the power generated by two reservoirs at different altitudes. In this process, water is pumped from the lower reservoir to the higher one and stored there. When electricity demand increases, water from the higher reservoir is pumped back to the lower reservoir via turbines, which then generate electricity through generators. Hydroelectric dams operate on the same principle: the dam holds water at a higher elevation upstream than downstream, and when electricity demand increases, the dam releases the water, which then flows through a hydroelectric turbine to generate electricity. Compressed air energy storage (CAES) technology is a mechanical solution. Other electrochemical technologies can also be used for energy storage, such as lithium-ion batteries, lead-acid batteries, or nickel-cadmium batteries, or flow batteries using electrolytes.

[0004] Compressed air energy storage (CAES) is a mature technology, with the first plant built in Germany in the late 1970s, storing 290 megawatts of energy. The principle of CAES is to use the generated, rather than consumed, electricity to compress air. To avoid damaging the compressor, the heat generated by compression is removed between each stage. The air, compressed to medium or high pressure (40 to 300 bar), is sent to natural storage sites, such as salt caverns, mines (salt, limestone, coal), or artificial storage sites, until the energy release stage. During the power generation stage, the stored air is extracted from the storage site to expand in a turbine generator. For basic CAES systems, such as those from the late 1970s, compressed air is used to supply gas turbines (also known as combustion turbines). These turbines burn natural gas through combustion chambers in the presence of compressed air, producing very hot combustion gases (500°C–800°C) that expand to generate electricity. The energy efficiency of the CAES process is approximately 50%.

[0005] A variant of CAES is the Adiabatic Compressed Air Energy Storage (ACAES) method. The main difference from the original CAES is that the heat generated during compression is no longer removed between stages, but rather stored to heat the air upstream of the turbine during the power generation stage. This internal reuse of thermal energy allows ACAES to achieve an efficiency of approximately 70%. Air cooling during the compression stage can be accomplished via indirect contact exchange with the heat transfer fluid in a heat exchanger. The heated heat transfer fluid is then stored and insulated to the maximum extent possible so that its heat can be released to the air during the expansion stage. This can also be achieved via direct contact exchange between the air and a heat storage mass based on sensible heat, or by means of a phase change material. In both cases, the heat from the air is stored directly in the mass, either within the material or through a phase change in the material. During the expansion stage, cool air is reinjected into the heat storage mass, and the air is heated by direct contact, either by capturing heat from the material or by a reverse phase change that allows that heat to be released. If the air has a certain level of humidity, this air cooling can cause water condensation. The condensate then needs to be extracted from the air loop to prevent damage to the downstream compressor.

[0006] The first solution to limit damage to the compressor is to extract water from the compression line by means of a gas / liquid separator located at each compression stage. Figure 1This ACAES system and method are schematically illustrated in the form of a block diagram. The diagram illustrates the energy storage phase during gas compression and the energy generation phase during gas expansion. The system according to the prior art includes a compression line (1) comprising one or more compression stages (3), which are determined based on the desired air pressure and the supplier's recommendations. In the illustrated embodiment, the compression line (1) comprises three compression stages (3). Each compression stage (3) includes a compression device (100, 101, 102), also referred to as 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 (10) used in the illustrated method is ambient air with a water saturation level related to its temperature and pressure. During the energy storage phase, the air is compressed in the compression line (1) and then sent to a compressed air storage device (1000) suitable for high pressure. A heat storage and recovery unit (200, 201, 202) is arranged after each compressor (100, 101, 102) in each compression stage (3) to cool the hot compressed air at the compressor outlet while storing the heat energy. The heat storage and recovery unit (200) is suitable for low pressure, the heat storage and recovery unit (201) is suitable for medium pressure, and the heat storage and recovery unit (202) is suitable for high pressure. If necessary, a cooling unit (300, 301, 302) can be arranged after the heat storage and recovery unit (200, 201, 202) to complete the cooling of the compressed air before the next compression stage or before storing the compressed air. Once the air is cooled and before the next compression stage, condensate from the humidity in the air is extracted from the compressed air stream by a gas / liquid separator (400, 401, 402), so that there is air at the compressor inlet without any trace of liquid water. This water condensation can occur in the heat storage and recovery unit (200, 201, 202) and / or the cooling unit (300, 301, 302). During the energy production phase, compressed air is expanded via one or more turbines (700, 701, 702) or an expansion stage, as recommended by the supplier, to generate electricity via a generator not shown in the figure. 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 method, the condensate is simply extracted, thus the associated energy is lost.

[0007] Other systems and methods for energy storage and recovery of compressed gases consider the recovery of energy contained in condensate.

[0008] For example, patent application FR-3,074,844 (WO-2019 / 115,121) discloses an improved ACAES system and method that re-injects condensate generated by air cooling into water used as the heat transfer fluid, allowing heat extracted from the air to be stored between each compression stage. However, this system and method are difficult to implement due to heat transfer between different water temperatures. The technology is based on a counter-current direct contact exchanger between the humid air to be cooled and the heated heat transfer fluid. During air cooling, humidity is generated and transferred by the heat transfer fluid. Due to this counter-current flow, the humidity encounters the hot air again and thus evaporates again. Water accumulates in the exchanger. Furthermore, the system is difficult to implement due to the circulation of the heat transfer fluid, requiring piping, pumping equipment, and additional storage devices, and also creating space constraints.

[0009] Patent application WO-16,012,764 discloses an ACAES method in which humidity from the air condenses upstream of an air reservoir during the compression stage, is stored, and then reinjected into the air during the expansion stage at the reservoir outlet. However, this method does not allow for the protection of the compressors in various compression stages by restricting the flow of water through them. Furthermore, this configuration does not optimize the energy recovered from the condensate. Additionally, the system is difficult to implement here due to the circulation of the heat transfer fluid, requiring piping, pumping devices, and additional storage units, and also creating space constraints.

[0010] Patent application WO-16,079,485 discloses an ACAES method in which humidity in the air condenses upstream of an air storage unit during the compression stage, is stored, and re-injected into the air during the expansion stage at the outlet of the air storage unit. However, this method does not allow for the protection of compressors in various compression stages by restricting the flow of water through it. Furthermore, this configuration does not optimize the energy recovered from the condensate. In addition, the system is difficult to implement due to the circulation of heat transfer fluids, requiring piping, pumping devices, and additional storage units, and also creating space constraints. The system also requires a combustion turbine during expansion to generate electricity via a Rankine cycle, while simultaneously expecting to store energy. Therefore, the efficiency of many devices is reduced. Summary of the Invention

[0011] This invention relates to a compressed gas energy storage and recovery system and method, which allows for optimization of system and method efficiency while limiting the space required and simplifying its operation. Therefore, this invention relates to a compressed gas energy storage and recovery system and method, comprising a compression line, an air storage device, and an expansion line. According to the invention, the compression line and expansion line include a heat storage device comprising heat storage particles. Furthermore, the expansion line includes means for injecting and mixing liquids within the expansion line. Thus, by injecting liquids, the gas flow rate in each expansion stage is increased, which allows for increased system and method efficiency. Moreover, by storing heat in the heat storage particles, the system and method are simple and applicable (no heat transfer fluid is used in the heat storage device).

[0012] This invention relates to a compressed gas energy storage and recovery system, comprising:

[0013] - A gas compression pipeline having at least two continuous compression stages, each compression stage including a compression unit and a heat storage and recovery unit arranged downstream of the compression unit in the direction of gas flow.

[0014] - At least one compressed gas storage device, arranged at the outlet of the gas compression pipeline, for storing the compressed gas.

[0015] - A gas expansion line for expanding the compressed gas stored in the compressed gas storage device, the gas expansion line comprising at least two consecutive expansion stages, each expansion stage comprising an expansion device and a conduit configured to circulate the compressed gas in at least one of the heat storage and recovery devices of the compression stage to heat the compressed gas.

[0016] The heat storage and recovery device includes heat storage particles, and each expansion stage includes a liquid delivery device, the liquid delivery device being located upstream of the heat storage device in the direction of gas flow.

[0017] According to one embodiment, each compression stage includes means for separating the gas and liquid.

[0018] Advantageously, for each compression stage, the gas / liquid separation device is arranged downstream of the heat storage and recovery device in the direction of gas flow.

[0019] Preferably, the system includes a plurality of liquid storage devices for storing the liquid at the outlet of the gas / liquid separator, and the delivery device delivers the liquid from the liquid storage devices.

[0020] According to one embodiment option, the compression pipeline includes as many compression stages as the expansion pipeline includes expansion stages, with each compression stage having a heat storage and recovery device for the corresponding expansion stage.

[0021] Advantageously, the compression line and the expansion line each comprise three stages.

[0022] According to one embodiment, at least one compression stage includes a cooling device downstream of the heat storage and recovery device in the direction of gas flow, preferably, the cooling device includes an air cooler.

[0023] According to one aspect, the expansion line includes at least one additional heat exchange device between the gas and the compressed gas at the outlet of the expansion line.

[0024] According to one feature, the at least one additional heat exchange device is arranged in the first expansion stage in the direction of gas flow.

[0025] Advantageously, the expansion line includes two additional heat exchange devices arranged in the two expansion stages.

[0026] According to one embodiment, the at least one additional heat exchange device is arranged in the direction of gas flow between the delivery device for the liquid and the heat storage and recovery device.

[0027] Furthermore, the present invention relates to a method for storing and recovering energy from compressed gas, which includes at least the following steps:

[0028] -In the energy storage phase:

[0029] a) In a compression pipeline comprising at least two compression stages, gas is continuously compressed at least twice, each compression stage comprising at least one compression device.

[0030] b) After each compression step, the heat of the compressed gas is recovered in at least one heat storage and recovery device.

[0031] c) Store the cooled compressed gas in at least one compressed gas storage device.

[0032] -In the energy recovery phase:

[0033] d) The compressed gas leaving the compressed gas storage device is circulated in an expansion line comprising at least two consecutive 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 the expansion device.

[0034] In this method, heat is stored in heat storage particles, and liquid is fed into the compressed gas before each expansion step and before the step of heating the gas.

[0035] According to one embodiment, after each compression step, the gas and the liquid present in the gas are separated.

[0036] Advantageously, the separated liquid is stored, and the liquid fed into the compressed gas is the stored liquid.

[0037] According to one embodiment, the same number of compression steps as the expansion step are performed, and a device for storing and recovering heat in each step b) is used to heat the compressed gas of the corresponding expansion step.

[0038] According to one aspect, after each heat recovery step, before sending the gas to the next compression step or to the compressed gas storage device, the compressed gas at the outlet of the heat storage and recovery device is cooled in a cooling device.

[0039] According to one feature, prior to at least one expansion step, the gas is heated at the outlet of the expansion line by at least one additional heat exchange with the gas.

[0040] Advantageously, in the direction of gas flow, the at least one additional heat exchange is performed for the first expansion step.

[0041] According to one implementation, two additional heat exchanges are performed for the two expansion steps.

[0042] According to one embodiment, the additional heat exchange is performed after the step of feeding the stored liquid into the compressed gas. Attached Figure Description

[0043] Other features and advantages of the system and method according to the invention will become apparent from the following description of embodiments given by way of non-limiting examples, with reference to the accompanying drawings, wherein:

[0044] -Already described Figure 1 A compressed gas energy storage and recovery system and method according to the prior art are shown.

[0045] - Figure 2 A compressed gas energy storage and recovery system and method according to a first embodiment of the present invention are shown.

[0046] - Figure 3 A compressed gas energy storage and recovery system and method according to a second embodiment of the present invention are shown.

[0047] - Figure 4A compressed gas energy storage and recovery system and method according to a third embodiment of the present invention are shown.

[0048] - Figure 5 A compressed gas energy storage and recovery system and method according to a fourth embodiment of the present invention are shown.

[0049] - Figure 6 A compressed gas energy storage and recovery system and method according to a fifth embodiment of the present invention are shown.

[0050] - Figure 7 A compressed gas energy storage and recovery system and method according to a sixth embodiment of the present invention are shown, and

[0051] - Figure 8 A compressed gas energy storage and recovery system and method according to a seventh embodiment of the present invention are shown. Detailed Implementation

[0052] This invention relates to a compressed gas energy storage and recovery system and method.

[0053] In this invention, the terms "upstream", "downstream", "inlet", "outlet", "before", and "after" are defined by the direction of gas flow during the energy storage phase (compression phase) and the energy recovery phase (expansion phase), respectively.

[0054] The system according to the present invention includes:

[0055] - A gas compression line (a compression line is understood as a gas line connecting a gas inlet to a compressed gas storage device via at least two consecutive compression devices), having at least two consecutive (in series) compression stages, each compression stage comprising:

[0056] • A gas compression device (compressor) that allows the pressure of gas to be increased for storage;

[0057] The compression device can be an axial or centrifugal compressor, or a compressor of any other technology, and

[0058] • A heat storage and recovery unit located downstream of the compression unit is used to store the heat generated by compression and reduce the gas temperature before the next compression stage or before the compressed gas storage unit.

[0059] - At least one compressed gas storage device for storing compressed gas at the outlet of a compression pipeline for later use; the compressed gas storage device may be a natural cave, such as a salt cavern, a former mine shaft or aquifer, or an artificial storage site.

[0060] - A gas expansion line (an expansion line is understood as a gas line connecting a compressed gas storage device to a gas outlet via at least one expansion device), having at least two consecutive (in series) expansion stages, each expansion stage comprising:

[0061] • At least one compressed gas expansion device for generating energy, such as a turbine that can be connected to a generator, and

[0062] • Pipes(s) used to circulate gas in a storage device within a compressed pipeline in order to recover stored heat and increase the gas temperature, thereby increasing the energy generated in the expansion device.

[0063] According to the present invention, the heat storage and recovery device comprises heat storage particles. Therefore, heat exchange occurs through direct exchange between the gas and the material, which is retained within the heat storage and recovery device. In other words, there is no circulation of the heat storage particles. Therefore, it is not necessary to have a dedicated system including storage tanks, pumping devices, and dedicated piping for the heat transfer fluid. For example, the material can be stone, concrete, gravel, phase change material (PCM) spheres (possibly encapsulated, preferably with a solid-liquid phase change), zeolite, or any similar material.

[0064] Additionally, each expansion stage includes a liquid delivery device. This liquid delivery device allows for mixing of gas and liquid in the expansion line. Therefore, by injecting water, the gas flow rate in each expansion stage is increased, which allows for increased system and method efficiency. The liquid delivery and mixing device is located in the expansion line upstream of the thermal storage unit, thus heating the re-injected liquid and water mixture in the thermal storage unit. This allows the liquid to evaporate, and therefore only gas is fed into the expansion unit.

[0065] According to an embodiment of the invention, the gas can be air. It may be air extracted from the surrounding environment. As a variation, it can include other gases.

[0066] According to one aspect of the invention, the liquid is water. It is particularly likely to be the humidity present in the gas when the gas is air. As a variation, it can include other liquids.

[0067] According to one embodiment, each compression stage may include a gas / liquid separator that allows the extraction of liquids present in the gas, particularly condensates of water present in the gas, and allows the removal of liquid traces that may be contained in the gas after cooling, which could damage the system, particularly the compression unit.

[0068] Furthermore, the system and method may include a liquid storage device for storing liquid extracted from the compression line. For example, a liquid storage device may be provided for each compression stage (and therefore for each gas / liquid separation device). Thus, the liquid can be stored at different pressures. Advantageously, a liquid delivery device allows delivery of liquid flowing from the liquid storage device, thereby making it possible to use the liquid recovered from condensation in the compression line.

[0069] According to one embodiment of the present invention, the gas / liquid separation device can be arranged downstream of the heat storage and recovery device. Therefore, the liquid formed by condensation in the heat storage and recovery device can be extracted.

[0070] Alternatively, the gas / liquid separator can be located upstream of the compressor or between the compressor and the heat storage and recovery unit.

[0071] Advantageously, the compression and expansion lines can include the same number of stages. In other words, the number of compression stages and the number of expansion stages can be the same. This provides a “symmetrical” design for the compression and expansion lines, with remarkably similar operating pressures and temperatures, which facilitates heat exchange in the heat storage and recovery unit and allows for the reinjection of liquid into the expansion stages corresponding to the respective compression stages. This simplifies the system and the method.

[0072] In this embodiment, the number of compression stages and expansion stages can be between two and six, preferably between three and five. For example, the number of compression stages and expansion stages can be three, which allows for good temperature and pressure management while maintaining a simple design.

[0073] As a variation, the number of compression stages and the number of expansion stages can be different. In this embodiment, at least a portion of the heat storage and recovery device and at least a portion of the liquid delivery device can be combined.

[0074] In addition, at least one compression stage may include a cooling device. This cooling device may be located downstream of the heat storage and recovery unit. The cooling device provides more significant gas cooling, which allows for a reduction in the size of the heat storage and recovery unit. These cooling devices may be air coolers or heat exchangers (shell / tube, plate, spiral, or other suitable technologies) that exchange heat with a heat transfer fluid, which may be water, propane, butane, or any other suitable coolant for the required cooling. The cooling device may be adapted to exchange with the pressure of the incoming air at each of them. This cooling device does not involve an energy recovery stage.

[0075] In this embodiment, the gas / liquid separation device can be arranged downstream of the cooling device. Therefore, the liquid formed by condensation in the heat storage and recovery device and the cooling device can be extracted.

[0076] According to one embodiment, the expansion line may include at least one additional heat exchange device between the gas and the compressed gas at the outlet of the expansion line. This cools the hot gas at the outlet of the expansion line and heats the compressed gas in the expansion line. Consequently, lost heat energy can be recovered, reducing the heating requirement for the compressed gas, which allows for a reduction in the size of at least one heat storage and recovery device (and thus, a reduction in the cost of the heat storage and recovery device).

[0077] According to an embodiment of this invention, an additional heat exchange device may be arranged in the first expansion stage. "First expansion stage" is understood as the first expansion stage through which the gas passes in the expansion line. In other words, the first expansion stage is adjacent to the compressed gas storage device. Therefore, the heat of the gas at the outlet of the expansion line is used to heat the cooler gas at the outlet of the compressed storage device. This allows for a reduction in the size of the heat storage and recovery device in the first expansion stage, which is the heat storage and recovery device with the highest pressure constraint and is therefore the most expensive heat storage and recovery device.

[0078] As a variation, an additional heat exchange device can be arranged in the expansion stage contained between the first expansion stage and the last expansion stage.

[0079] According to one aspect of this embodiment, the expansion line may include two additional heat exchange devices arranged in two different expansion stages. Therefore, the size of the two heat storage and recovery devices can be reduced. In this embodiment, the two additional heat exchange devices may be passed in series by gas at the expansion line outlet. Preferably, the two additional heat exchange devices may be arranged in the first two expansion stages. Thus, the heat of the gas at the expansion line outlet is used to heat the cooler gas at the outlet of the compression storage device and the outlet of the first expansion stage, which allows for a reduction in the size of the heat storage and recovery devices in the first two expansion stages, which are the heat storage and recovery devices with the highest pressure constraints and are therefore the most expensive. In this embodiment of the invention, the gas at the expansion line outlet may first flow through the additional heat exchange device of the second expansion stage and then through the additional heat exchange device of the first expansion stage.

[0080] Advantageously, an additional heat exchange device can be arranged between the liquid delivery device and the heat storage and recovery device. Therefore, this additional heat exchange device can heat the gas-liquid mixture, promoting liquid evaporation.

[0081] As a variation, the additional heat exchange device can be arranged before the liquid delivery device, or between the heat storage and recovery device and the expansion device.

[0082] Furthermore, the present invention relates to a method for storing and recovering compressed gas energy.

[0083] The method according to the present invention includes the following steps:

[0084] - During the energy storage phase (compression phase)

[0085] a) Compression of gas continuously at least twice in a compression pipeline comprising at least two compression stages, each compression stage comprising at least one compression device.

[0086] b) After each compression step, the heat of the compressed gas is recovered in at least one heat storage and recovery device.

[0087] c) The cooled compressed gas is stored at the outlet of the compressed gas pipeline in the compressed gas storage device.

[0088] - During the energy recovery phase (expansion phase)

[0089] d) The compressed gas leaving the compressed gas storage device is circulated in an expansion line comprising at least two consecutive 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 the expansion device.

[0090] Furthermore, according to the present invention, heat is stored and recovered in heat storage particles. In other words, the heat storage and recovery device comprises heat storage particles. Therefore, heat exchange occurs through direct exchange between the gas and the material, which remains in the heat storage and recovery device. In other words, there is no circulation of the heat storage particles. Therefore, it is not necessary to have a dedicated system including tanks, pumping devices, and dedicated piping for storing the heat transfer fluid. For example, the material can be stone, concrete, gravel, phase change material (PCM) spheres, zeolite, or any similar material.

[0091] Furthermore, prior to each expansion step and before the gas heating step, liquid is fed into and mixed with the compressed gas. Therefore, each expansion stage includes a liquid delivery and mixing device, allowing the use of liquid recovered from condensate in the compression line. Thus, by injecting liquid, the gas flow rate in each expansion stage is increased, which allows for increased system and method efficiency. This liquid delivery and mixing device is located in the expansion line upstream of the thermal storage device, whereby the injected liquid and water mixture is heated, allowing the liquid to evaporate, and therefore only gas is fed into the expansion device.

[0092] Preferably, the compressed gas energy storage and recovery method can use a compressed gas energy storage and recovery system according to any of the above variations or combinations of variations.

[0093] According to one embodiment of the present invention, the gas may be air. It may be air extracted from the surrounding environment.

[0094] According to one aspect of the invention, the liquid may be water. In particular, when the gas is air, it is especially likely to be the humidity present in the gas.

[0095] According to an embodiment of the present invention, after each compression step, the gas and liquid present in the gas can be separated.

[0096] Furthermore, the method may include a liquid storage step for storing the liquid extracted from the compression line. For example, a liquid storage device may be provided for each compression step (and thus for each gas / liquid separation step). Therefore, the liquid can be stored at different pressures. Advantageously, the liquid fed into the gas is from the storage step, thus making it possible to use liquid recovered from the condensate in the compression line.

[0097] According to one embodiment of the invention, the gas / liquid separation step can be performed after the thermal storage step. Therefore, the liquid formed by condensation in the thermal storage and recovery device can be extracted.

[0098] Advantageously, the same number of compression steps as expansion steps can be performed. In this case, the compression line and expansion line can include the same number of stages. In other words, the number of compression steps and the number of expansion steps can be the same. This embodiment achieves a “symmetrical” design of the compression and expansion lines, with remarkably similar operating pressures and temperatures, which facilitates heat exchange in the heat storage and recovery device and allows the liquid to be reinjected into the expansion stage corresponding to the respective compression stage. Therefore, the system and method are simplified.

[0099] In this embodiment, the number of compression stages and expansion stages can be between two and six, preferably between three and five. For example, the number of compression stages and expansion stages can be three, which allows for good temperature and pressure management while maintaining a simple design.

[0100] As a variation, the number of compression stages and the number of expansion stages can be different. In this embodiment, at least a portion of the heat storage and recovery device and at least a portion of the liquid delivery device can be combined (centralized).

[0101] In addition, the energy storage stage may include a cooling step. This cooling step can be performed using a cooling device after the heat storage step. This cooling step can more significantly cool the gas, which allows for a reduction in the size of the heat storage and recovery device. These cooling devices can be air coolers or heat exchangers (shell / tube, plate, spiral, or other suitable technologies) that exchange heat with a heat transfer fluid, which can be water, propane, butane, or any other suitable coolant for the required cooling. The cooling device can be adapted to exchange inlet air pressure with each of them.

[0102] In this embodiment, the gas / liquid separation device can be operated after the cooling step. Therefore, the liquid formed by condensation in the heat storage and recovery device and the cooling device can be extracted.

[0103] According to one embodiment, the energy recovery stage may include at least one additional heat exchange step between the gas and compressed gas at the expansion line outlet. This cools the hot gas at the expansion line outlet while simultaneously heating the compressed gas in the expansion line. Consequently, lost heat energy can be recovered, reducing the need for compressed gas heating, which allows for a reduction in the size of at least one heat storage and recovery unit (and thus, a reduction in the cost of the heat storage and recovery unit).

[0104] According to the implementation of this embodiment, additional heat exchange can be provided for the first expansion step (in the first expansion stage). "First expansion stage" is understood as the first expansion stage through which the gas passes in the expansion line. In other words, the first expansion step follows the compressed gas storage step. Therefore, using the heat of the gas at the expansion line outlet to heat the cooler gas at the outlet of the compressed storage device allows for a reduction in the size of the heat storage and recovery unit for the first expansion stage, which is the heat storage and recovery unit with the highest pressure constraints and is therefore the most expensive heat storage and recovery unit.

[0105] As a variation, the additional heat exchange can be performed in an expansion step between the first and last expansion steps.

[0106] According to one aspect of this embodiment, the energy recovery stage may include two additional heat exchangers, which are performed in two different expansion steps. Therefore, the size of the two heat storage and recovery devices can be reduced. In this embodiment, the two additional heat exchangers can be connected in series by the gas passing through the expansion line outlet. Preferably, two additional heat exchangers can be provided in the first two expansion steps. Thus, the heat of the gas at the expansion line outlet is used to heat the cooler gas at the outlet of the compression storage device and the outlet of the first expansion stage, which allows for a reduction in the size of the heat storage and recovery devices in the first two expansion stages, which are the most expensive heat storage and recovery devices due to their highest pressure constraints. In this embodiment of the invention, the gas at the expansion line outlet can first flow through the additional heat exchanger of the second expansion stage and then through the additional heat exchanger of the first expansion stage.

[0107] Advantageously, an additional heat exchange can be performed between the liquid delivery step and the heat recovery step of the heat storage and recovery device. Therefore, this additional heat exchange can heat the gas-liquid mixture, promoting liquid evaporation.

[0108] As a variation, this additional heat exchange can be performed before the liquid delivery step.

[0109] Figure 2 A system and method for energy storage and recovery of compressed gas (here, air) according to a first embodiment of the present invention are illustrated schematically by means of a non-limiting example. According to this first embodiment, the method and system include a compression line (1) comprising three compression stages (3), depending on the air pressure to be achieved. Each compression stage (3) includes a compression device (100, 101, 102), also referred to as a "compressor". These compressors (100, 101, 102) may be axial or centrifugal, or of any other technology. Compressor (100) is a low-pressure compressor, compressor (101) is a medium-pressure compressor, and compressor (102) is a high-pressure compressor. The gas (10) used in the system and method is ambient air having a water saturation level related to its temperature and pressure. A so-called "low-pressure element" (e.g., turbine, compressor, etc.) is an element suitable for a low pressure in which a gas or liquid flows, a medium-pressure element is an element suitable for a medium pressure in which a gas or liquid flows, and a high-pressure element is an element suitable for a high pressure in which a gas or liquid flows.

[0110] During the energy storage phase (1), air is compressed in the compression line (1) and then sent to a compressed air storage device (1000) suitable for high pressure. The compressed air storage device (1000) can be a natural cave, such as a salt cavern, a former mine, an aquifer, or an artificial storage site.

[0111] Heat storage and recovery units (200, 201, 202) are arranged after each compressor (100, 101, 102) to cool the hot compressed air at the compressor outlet while storing the heat energy. The exchange / storage occurs through direct contact between the air and a material to allow the storage of heat from the air. This material can be stone, concrete, gravel, or any other suitable solid material. The heat storage and recovery units (200, 201, 202) are adapted to the pressure of the incoming air, which outputs its energy to each of these heat storage and recovery units. Heat storage and recovery unit (200) is adapted for low pressure, heat storage and recovery unit (201) for medium pressure, and heat storage and recovery unit (202) for high pressure.

[0112] During the energy generation phase, compressed air flows through an expansion line (2) comprising three expansion stages (4). The air is expanded via one or more expansion devices, such as turbines (700, 701, 702) arranged in each expansion stage (4), to generate electricity via a generator (not shown). Turbine (702) is a low-pressure turbine, turbine (701) is a medium-pressure turbine, and turbine (700) is a high-pressure turbine.

[0113] As the first step in each expansion stage (4), condensate is injected into the compressed air via mixers (600, 601, 602). The compressed air / water mixture is heated by heat storage and recovery devices (200, 201, 202) that have been heat-loaded during the previous compression stage (1) before entering the turbine. The condensate injected in each expansion stage (4) is evaporated, and the air is heated. Therefore, there is no liquid water at the inlet of the turbines (700, 701, 702), which is beneficial for the normal operation of the turbines. In addition, the higher flow rate resulting from the reinjection of water and the high temperature at the inlet of the turbines (700, 701, 702) provide better processing efficiency.

[0114] Figure 3 A system and method for energy storage and recovery of compressed gas (here, air) according to a second embodiment of the present invention are illustrated schematically by means of a non-limiting example. This second embodiment corresponds to the first embodiment, wherein cooling devices (300, 301, 302) have been added to the compression line (1). Therefore, for this embodiment, only the compression line (1) is described.

[0115] Each compression stage (3) includes a compression unit (100, 101, 102), also referred to as a "compressor". These compressors (100, 101, 102) can be axial or centrifugal, or of any other technology. Compressor (100) is a low-pressure compressor, compressor (101) is a medium-pressure compressor, and compressor (102) is a high-pressure compressor. The gas (10) used in this system and method is ambient air with a water saturation level related to its temperature and pressure.

[0116] During the energy storage phase (1), air is compressed in a compression line and then sent to a compressed air storage device (1000) suitable for high pressure. The compressed air storage device (1000) can be a natural cave, such as a salt cavern, a former mine, an aquifer, or an artificial storage site.

[0117] Heat storage and recovery units (200, 201, 202) are arranged after each compressor (100, 101, 102) to cool the hot compressed air at the compressor outlet while storing the heat energy. The exchange / storage occurs through direct contact between the air and a material to allow the storage of heat from the air. This material can be stone, concrete, gravel, or any other suitable solid material. The heat storage and recovery units (200, 201, 202) are adapted to the pressure of the incoming air, which outputs its energy to each of these heat storage and recovery units. Heat storage and recovery unit (200) is adapted for low pressure, heat storage and recovery unit (201) for medium pressure, and heat storage and recovery unit (202) for high pressure. If desired, cooling units (300, 301, 302) can be arranged after the heat storage and recovery units (200, 201, 202) to complete the cooling of the compressed air before the next compression stage or before compressed air storage. These cooling devices (300, 301, 302) can be air coolers or heat exchangers (shell / tube, plate, spiral, or other suitable technologies) that exchange heat with a heat transfer fluid, which can be water, propane, butane, or any other coolant suitable for the required cooling. The cooling devices (300, 301, 302) are adapted to the pressure of the incoming air, which exchanges with each of these cooling devices. Cooling device (300) is suitable for low pressure, cooling device (301) for medium pressure, and cooling device (302) for high pressure.

[0118] Figure 4A system and method for energy storage and recovery of compressed gas (here, air) according to a third embodiment of the present invention are illustrated schematically by means of a non-limiting example. According to this third embodiment, the method and system include a compression line comprising three compression stages (3), depending on the air pressure to be achieved. Each compression stage (3) includes a compression device (100, 101, 102), also referred to as a compressor. These compressors (100, 101, 102) may be axial or centrifugal, or of any other technology. Compressor (100) is a low-pressure compressor, compressor (101) is a medium-pressure compressor, and compressor (102) is a high-pressure compressor. The gas (10) used in the system and method is ambient air with a water saturation level related to its temperature and pressure.

[0119] During the energy storage phase, air is compressed in a compression line (1) and then sent to a compressed air storage device (1000) suitable for high pressure. The compressed air storage device (1000) can be a natural cave, such as a salt cavern, a former mine, an aquifer, or an artificial storage site.

[0120] Heat storage and recovery units (200, 201, 202) are arranged after each compressor (100, 101, 102) to cool the hot compressed air at the compressor outlet while storing the heat energy. The exchange / storage occurs through direct contact between the air and a material to allow the storage of heat from the air. This material can be stone, concrete, gravel, or any other suitable solid material. The heat storage and recovery units (200, 201, 202) are adapted to the pressure of the incoming air, which outputs its energy to each of these heat storage and recovery units. Heat storage and recovery unit (200) is adapted for low pressure, heat storage and recovery unit (201) for medium pressure, and heat storage and recovery unit (202) for high pressure.

[0121] Once the air has cooled, and before the next compression stage, condensate (i.e., liquid present in the air) from the humidity of the air is extracted from the compression line via gas / liquid separators (400, 401, 402) so that there is no trace of liquid water at the inlet of the compressor or compressed gas storage unit (1000). This water condensation can occur in heat storage and recovery units (200, 201, 202). The condensate from each compression stage is sent to liquid storage units (500, 501, 502), each liquid storage unit being subjected to the pressure of the water extracted from the air; in other words, liquid storage unit (500) is suitable for low pressure, liquid storage unit (501) for medium pressure, and liquid storage unit (502) for high pressure.

[0122] During the energy generation phase, compressed air flows through an expansion line (2) comprising three expansion stages (4). The air is expanded via one or more expansion devices, such as turbines (700, 701, 702) arranged in each expansion stage (4), to generate electricity via a generator (not shown). Turbine (702) is a low-pressure turbine, turbine (701) is a medium-pressure turbine, and turbine (700) is a high-pressure turbine.

[0123] As the first step in each expansion stage (4), condensate from the liquid storage units (500, 501, 502) is reinjected into compressed air at the same pressure level via mixers (600, 601, 602). The compressed air / condensate mixture is heated by heat storage and recovery units (200, 201, 202) that have been thermally loaded during the previous compression stage (1) before entering the turbine. The condensate reinjected in each expansion stage is evaporated, and the air is heated. Therefore, there is no liquid water at the inlet of the turbines (700, 701, 702), which is beneficial for normal operation, and the higher flow rate resulting from the reinjection of water and the higher temperature at the inlet of the turbines (700, 701, 702) provide better processing efficiency.

[0124] Figure 5 A system and method for energy storage and recovery of compressed gas (here, air) according to a fourth embodiment of the present invention are illustrated schematically by means of a non-limiting example. This fourth embodiment differs from the third embodiment in the number of compression stages and the number of expansion stages. In this embodiment, the compression line (1) includes two compression stages (3), and the expansion line (2) includes two expansion stages (4).

[0125] This third embodiment can also be modified by adding compression and / or expansion stages.

[0126] Figure 6 A system and method for energy storage and recovery of compressed gas (here, air) according to a fifth embodiment of the present invention are illustrated schematically by means of a non-limiting example. This fifth embodiment corresponds to the third embodiment, wherein cooling devices (300, 301, 302) have been added to the compression line (1). Therefore, for this embodiment, only the compression line (1) is described.

[0127] According to this fifth embodiment, the method and system include a compression line (1) that, depending on the air pressure to be achieved, comprises three compression stages (3). Each compression stage (3) includes a compression device (100, 101, 102), also referred to as a "compressor". These compressors (100, 101, 102) can be axial, centrifugal, or of any other technology. Compressor (100) is a low-pressure compressor, compressor (101) is a medium-pressure compressor, and compressor (102) is a high-pressure compressor. The compressed gas (10) used in this system and method is ambient air with a water saturation level related to its temperature and pressure.

[0128] During the energy storage phase, air is compressed in a compression line (1) and then sent to a compressed air storage device (1000) suitable for high pressure. The compressed air storage device (1000) can be a natural cave, such as a salt cavern, a former mine, an aquifer, or an artificial storage site.

[0129] Heat storage and recovery units (200, 201, 202) are arranged after each compressor or compression stage (100, 101, 102) to cool the hot compressed air at the compressor outlet while storing the heat energy. The exchange / storage occurs through direct contact between the air and a material to allow the storage of heat from the air. This material can be stone, concrete, gravel, or any other suitable solid material. The heat storage and recovery units (200, 201, 202) are adapted to the pressure of the incoming air, which outputs its energy to each of these heat storage and recovery units. Heat storage and recovery unit (200) is adapted for low pressure, heat storage and recovery unit (201) for medium pressure, and heat storage and recovery unit (202) for high pressure. If desired, cooling units (300, 301, 302) can be arranged after the heat storage and recovery units (200, 201, 202) to complete the cooling of the compressed air before the next compression stage or before the storage of the compressed air. These cooling devices (300, 301, 302) can be air coolers or heat exchangers (shell / tube, plate, spiral, or other suitable technologies) that exchange heat with a heat transfer fluid, which can be water, propane, butane, or any other coolant suitable for the required cooling. The cooling devices (300, 301, 302) are adapted to the pressure of the incoming air, which exchanges with each of these cooling devices. Cooling device (300) is suitable for low pressure, cooling device (301) for medium pressure, and cooling device (302) for high pressure.

[0130] Once the air is cooled, and before the next compression stage, condensate (i.e., liquid present in the air) from the humidity of the air is extracted from the compression line via gas / liquid separators (400, 401, 402) so that there is no trace of liquid water at the inlet of the compressor or compressed gas storage unit (1000). This water condensation can occur in heat storage and recovery units (200, 201, 202) and / or cooling units (300, 301, 302). The condensate at each compression stage is sent to liquid storage units (500, 501, 502), each of which is subjected to the pressure at which water is extracted from the air; in other words, liquid storage unit (500) is suitable for low pressure, liquid storage unit (501) for medium pressure, and liquid storage unit (502) for high pressure.

[0131] This fifth embodiment can also be modified by adjusting (adapting) the number of compression stages and / or expansion stages.

[0132] Figure 7 A system and method for energy storage and recovery of compressed gas (here, air) according to a sixth embodiment of the present invention are illustrated schematically by means of a non-limiting example. This sixth embodiment corresponds to the fifth embodiment, in which an additional heat exchanger (800) is provided in an expansion line (2) between the exhaust air and the compressed gas. Therefore, for this embodiment, only the expansion line (2) is described.

[0133] During the energy generation phase, compressed air flows through an expansion line (2) comprising three expansion stages (4). The air is expanded via one or more expansion devices, such as turbines (700, 701, 702) arranged in each expansion stage (4), to generate electricity via a generator (not shown). Turbine (702) is a low-pressure turbine, turbine (701) is a medium-pressure turbine, and turbine (700) is a high-pressure turbine.

[0134] As the first step in each expansion stage (4), condensate from the liquid storage units (500, 501, 502) is reinjected into the compressed air at the same pressure level via mixers (600, 601, 602). The compressed air / condensate mixture is heated by heat storage and recovery units (200, 201, 202) that have been heat-loaded during the previous compression stage (1) before entering the turbine. The condensate reinjected in each expansion stage (4) is evaporated, and the air is heated. Therefore, there is no liquid water at the inlet of the turbines (700, 701, 702), which is beneficial for the normal operation of the turbines. In addition, the higher flow rate resulting from the reinjection of water and the high temperature of the expansion lines (2) at the inlet of the turbines (700, 701, 702) provide better processing efficiency.

[0135] The heat from the air exiting the low-pressure turbine (700) is used to heat the air from the compressed gas storage unit (1000) and mixed with condensate (28) via an additional heat exchanger (800). In this embodiment, the additional heat exchanger (800) is arranged in the first expansion stage (4) of the expansion line (2). Furthermore, the additional heat exchanger (800) is arranged between the mixer (600) and the heat storage and recovery unit (202). This additional heat exchanger (800) can be of the shell / tube, plate, or helical type, or any other suitable technology.

[0136] The sixth embodiment can also be modified by adjusting (adapting) the number of compression stages and / or expansion stages.

[0137] In addition, the compression line (1) can also be similar to Figure 4 The embodiments are those without cooling devices (300, 301, 302).

[0138] Figure 8 A system and method for energy storage and recovery of compressed gas (here, air) according to a seventh embodiment of the present invention are illustrated schematically by means of a non-limiting example. This seventh embodiment corresponds to the fifth embodiment, in which two additional heat exchangers (800) are disposed in an expansion line (2) between the air and the compressed gas. Therefore, for this embodiment, only the expansion line (2) is described.

[0139] During the energy generation phase, compressed air flows through an expansion line (2) comprising three expansion stages (4). The air is expanded via one or more expansion devices, such as turbines (700, 701, 702) arranged in each expansion stage (4), to generate electricity via a generator (not shown). Turbine (702) is a low-pressure turbine, turbine (701) is a medium-pressure turbine, and turbine (700) is a high-pressure turbine.

[0140] As the first step in each expansion stage (4), condensate from the liquid storage units (500, 501, 502) is reinjected into the compressed air at the same pressure level via mixers (600, 601, 602). The compressed air / condensate mixture is heated by heat storage and recovery units (200, 201, 202) that have been heat-loaded during the previous compression stage (1) before entering the turbine. The condensate reinjected in each expansion stage is evaporated, and the air is heated. Therefore, there is no liquid water at the inlet of the turbines (700, 701, 702), which is beneficial for the normal operation of the turbines. In addition, the higher flow rate due to the reinjection of water and the high temperature of the expansion lines (2) at the inlet of the turbines (700, 701, 702) provide better processing efficiency.

[0141] The heat from the air leaving the low-pressure turbine (700) is used to heat the air from the compressed gas storage unit (1000) and mixed with condensate (28) via an additional heat exchanger (800), as well as the air from the second expansion stage and mixed with condensate (33) via an additional heat exchanger (801). In this embodiment, the additional heat exchangers (800, 801) are arranged in the first expansion stage (4) and the second expansion stage (4) of the expansion line (2). Furthermore, in each expansion stage, the additional heat exchangers (800, 801) are arranged between the mixer (600, 601) and the heat storage and recovery unit (202, 201). These additional heat exchangers (800, 801) can be of the shell / tube, plate, or spiral type, or any other suitable technology. In the illustrated embodiment, air (40) from the low-pressure turbine (702) including waste heat is heated in series with a flow (33) upstream of the medium-pressure thermal energy storage device (201), and then with a flow (28) upstream of the high-pressure thermal energy storage device (202).

[0142] This seventh embodiment can also be modified by adjusting (adapting) the number of compression stages and / or expansion stages.

[0143] In addition, compression lines can also be similar to Figure 4 The embodiments are those without cooling devices (300, 301, 302).

[0144] It goes without saying that the present invention is not limited to the embodiments of the systems and methods described above by way of example, but includes all variant embodiments.

[0145] Comparison Examples

[0146] The features and advantages of the method of the present invention will become clearer by reading the following application examples.

[0147] Example 1 – Not according to the present invention

[0148] This example implements Figure 1 The system and method shown are not based on the present invention.

[0149] During the compression phase (1), an external airflow (10) with a pressure of 1.02 bar (0.102 MPa), a temperature of 27°C, and a humidity of 14.6 g water / kg air is compressed by a low-pressure compressor (100), which exits the compressor (11) at a temperature of 255°C and a pressure of 6 bar (0.6 MPa). The flow (11) is sent to a low-pressure heat storage and recovery unit (200), which cools the air to a temperature of 90°C (12) and stores the heat energy until the expansion phase (2). The flow (12) is cooled again by a cooling unit (300) until it reaches a temperature of 50°C (13) at the outlet. The flow (13) then consists of water and air from the humidity of the air, which condenses in (200) and / or (300) during the cooling phase. The condensate (14) is separated from the compression line (1) in a gas / liquid separator (400) operating at the same pressure as the flow (13). The flow (15), now entirely gaseous, is compressed by a medium-pressure compressor (101) and flows out (16) from the compressor at a temperature of 275°C and a pressure of 28 bar (2.8 MPa). The flow (16) is sent to a medium-pressure heat storage and recovery unit (201), which cools the air to a temperature of 100°C (17) and stores the heat energy until the expansion phase (2). The flow (17) is cooled again by a cooling unit (301) until it reaches a temperature of 50°C (18) at the outlet. The flow (18) then consists of water and air with humidity from the air, which condenses in (201) and / or (301) during the cooling phase. The condensate (19) is separated from the compression line (1) in a gas / liquid separator (401) operating at the pressure of the stream (18). The stream (20), now completely gaseous, is compressed by a high-pressure compressor (102) and flows out of the high-pressure compressor (21) at a temperature of 250°C and a pressure of 117 bar (11.7 MPa). The stream (21) is sent to a high-pressure heat storage and recovery unit (202), which cools the air to a temperature of 45°C (22) and stores the heat energy until the expansion phase (2). The stream (22) is cooled again by a cooling unit (302) until it reaches a temperature of 30°C at the outlet (23), which is the air storage temperature. The stream (23) then consists of water and air with humidity from the air, which condenses in (202) and / or (302) during the cooling phase. The condensate (24) is separated from the compression line (1) in a gas / liquid separator (402) operating at the pressure of the flow (23).

[0150] The air stream (25) compressed to a pressure of 117 bar (11.7 MPa) and a temperature of 30°C is then sent to the compressed air storage device (1000) until the energy recovery stage (2).

[0151] When power generation is required, a compressed air stream (26) leaving the compressed air storage unit (1000) at a pressure of 117 bar (11.7 MPa) and a temperature of 30°C is heated in a high-pressure heat storage and recovery unit (202), which releases the heat stored during the compression phase (1) until the stream (27) reaches a temperature of 240°C. This heated compressed air stream (27) expands in a high-pressure turbine (702) and generates electricity via a generator until it reaches a pressure of 28 bar (2.8 MPa) and a temperature of 85°C at the outlet (28). The stream (28) is heated in a medium-pressure heat storage and recovery unit (201), which releases the heat stored during the compression phase (1) until the stream (29) reaches a temperature of 265°C. The hot compressed air stream (29) expands in an intermediate-pressure turbine (701) and generates electricity via a generator until it reaches a pressure of 5 bar (0.5 MPa) and a temperature of 75°C (30) at the outlet. The stream (30) is heated in a low-pressure heat storage and recovery unit (200), which releases the heat stored during the compression phase (1) until the stream (31) reaches a temperature of 245°C. The hot compressed stream (31) expands in a low-pressure turbine (700) and generates electricity via a generator until it reaches a pressure of 1.02 bar (0.102 MPa) and a temperature of 80°C (32) at the outlet.

[0152] For a compressor power consumption of 100MW, the efficiency of the energy storage process in Example 1 is 69.6%. The total condensate flow rate in the three compression stages is 7.5 tons per hour (t / h). The heat storage capacity is 87 MWth (megawatt-hours of thermal energy), and the required cooling capacity is 20.5 MWth.

[0153] Example 2 of the present invention

[0154] This example implements according to Figure 3 The system and method of the present invention are shown in the embodiments.

[0155] During the compression phase (1), a dry air stream (10) at a pressure of 1.02 bar (0.102 MPa) and a temperature of 27°C without any water residue is compressed by a low-pressure compressor (100), exiting the compressor at a temperature of 260°C and a pressure of 6 bar (0.6 MPa). The stream (11) is sent to a low-pressure heat storage and recovery unit (200), which cools the air to a temperature of 60°C (12) and stores the heat energy until the expansion phase (2). The stream (12) is cooled again by a cooling unit (300) until it reaches a temperature of 50°C (13) at the outlet. The stream (13) is compressed by a medium-pressure compressor (101), exiting the compressor at a temperature of 275°C and a pressure of 28 bar (2.8 MPa) (14). Stream (14) is sent to a medium-pressure heat storage and recovery unit (201), which cools the air to a temperature of 80°C (15) and stores the heat energy until the expansion phase (2). Stream (15) is cooled again by a cooling unit (301) until it reaches a temperature of 50°C at the outlet (16). Stream (16) is compressed by a high-pressure compressor (102) and exits (17) at a temperature of 250°C and a pressure of 117 bar (11.7 MPa). Stream (17) is sent to a high-pressure heat storage and recovery unit (202), which cools the air to a temperature of 40°C (18) and stores the heat energy until the expansion phase (2). Stream (18) is cooled again by a cooling unit (302) until it reaches a temperature of 30°C (19) at the outlet, 30°C being the air storage temperature.

[0156] The air stream (19) compressed to a pressure of 117 bar (11.7 MPa) and a temperature of 30°C is then sent to the compressed air storage device (1000) until the energy recovery stage (2).

[0157] When power generation is required, an optimal flow of liquid water (21) at a pressure of 117 bar (11.7 MPa) and a temperature of 30°C is injected via a mixer (600) into a stream of compressed air (20) exiting the storage device (1000) to form a stream (22). The stream (22) is heated in a high-pressure heat storage and recovery device (202), which releases the heat stored during the compression phase (1) until the stream (23) reaches a temperature of 240°C. This heated stream of compressed air (23) expands in a high-pressure turbine (700) and generates electricity via a generator until it reaches a pressure of 28 bar (2.8 MPa) and a temperature of 85°C (24) at the outlet. An optimal flow of liquid water (25) at a pressure of 28 bar (2.8 MPa) and a temperature of 50°C is injected via a mixer (601) into the stream of compressed air (24) to form a stream (26). The stream (26) is heated in a medium-pressure heat storage and recovery unit (201), which releases the heat stored during the compression phase (1) until the stream (27) reaches a temperature of 265°C. The heated compressed air stream (27) expands in a medium-pressure turbine (701) and generates electricity via a generator until it reaches a pressure of 5 bar (0.5 MPa) and a temperature of 75°C (28) at the outlet. An optimal flow of liquid water (29) at a pressure of 6 bar (0.6 MPa) and a temperature of 50°C is injected into the compressed air stream (28) via a mixer (600) to form a stream (30). The stream (30) is heated in a medium-pressure heat storage and recovery unit (200), which releases the heat stored during the compression phase (1) until the stream (31) reaches a temperature of 245°C. The hot compressed air stream (31) expands in a low-pressure turbine (702) and generates electricity via a generator until it reaches a pressure of 1.02 bar (0.102 MPa) and a temperature of 80°C (32) at the outlet.

[0158] For a 100MW compressor, the energy storage method has an efficiency of 71.6% with a total liquid water flow rate of 9.1 t / h injected into the three compression stages. The thermal storage capacity is 94.6 MWth, and the required cooling capacity is 8.0 MWth.

[0159] Therefore, compared to Example 1 without the invention, by increasing the flow rate through the turbine during expansion, water injection allows for a process efficiency increase of more than 2% and a reduction in the required cooling capacity.

[0160] Example 3 according to the present invention

[0161] This example implements according to Figure 6 The system and method of the present invention are shown in the embodiments.

[0162] During the compression phase (1), an external airflow (10) with a pressure of 1.02 bar (0.102 MPa), a temperature of 27°C, and a humidity of 14.6 g water / kg air is compressed by a low-pressure compressor (100) and exits (11) at a temperature of 255°C and a pressure of 6 bar (0.6 MPa). The flow (11) is sent to a low-pressure heat storage and recovery unit (200), which cools the air to a temperature of 80°C (12) and stores the heat energy until the expansion phase (2). The flow (12) is cooled again at the outlet by a cooling unit (300) to a temperature of 50°C (13). The flow (13) then consists of water and air from the humidity of the air, which condenses in (200) and / or (300) during the cooling phase. The condensate (14) is separated from the flow in the compression line (1) in a gas / liquid separator (400) operating at the same pressure as the flow (13), and then sent to the liquid storage unit (500) at a maintained pressure of 6 bar (0.6 MPa). The flow (15), which is again completely gaseous, is compressed by a medium-pressure compressor (101) and exits (16) at a temperature of 275°C and a pressure of 28 bar (2.8 MPa). The flow (16) is sent to a medium-pressure heat storage and recovery unit (201), which cools the air to a temperature of 80°C (17) and stores the heat energy until the expansion phase (2). The flow (17) is cooled again by a cooling unit (301) until it reaches a temperature of 50°C at the outlet (18). The flow (18) then consists of water and air with humidity from the air, which condenses in (201) and / or (301) during the cooling phase. The condensate (19) is separated from the flow in the compression line (1) in a liquid / gas separator (401) operating at the same pressure as the flow (18), and then sent to a liquid storage device (501) at a pressure maintained at 28 bar (2.8 MPa). The flow (20), which is now completely gaseous, is compressed by a high-pressure compressor (102) and flows out from the high-pressure compressor (21) at a temperature of 250°C and a pressure of 117 bar (11.7 MPa). The flow (21) is sent to a high-pressure heat storage and recovery device (202), which cools the air to a temperature of 40°C (22) and stores the heat energy until the expansion phase (2). The flow (22) is cooled again by a cooling device (302) until it reaches a temperature of 30°C (23) at the outlet, which is the air storage temperature. The flow (23) then consists of water and air with humidity from the air, which condenses in (202) and / or (302) during the cooling phase. The condensate (24) is separated from the flow in the compression line (1) in a gas / liquid separator (402) operating at the pressure of the flow (23), and then sent to the liquid storage device (502) at a maintained pressure of 117 bar (11.7 MPa).

[0163] Then, a compressed air stream (25) with a pressure of 117 bar (11.7 MPa) and a temperature of 30°C is sent to the compressed air storage device (1000) until the energy recovery stage (2).

[0164] When power generation is required, a stream (27) of condensate (117 bar, 11.7 MPa) at a temperature of 30°C from a liquid storage unit (502) is reinjected via a mixer (600) into a stream (26) of compressed air leaving the compressed air storage unit (1000) to form a stream (28). The stream (28) is heated in a high-pressure heat storage and recovery unit (202), which releases the heat stored during the compression phase, until the stream (28) reaches a temperature of 240°C. This heated compressed air stream (29) expands in a high-pressure turbine (700) and generates electricity via a generator until it reaches a pressure of 28 bar (2.8 MPa) and a temperature of 85°C (30) at the outlet. A stream (31) of condensate (28 bar, 2.8 MPa) at a temperature of 50°C from a liquid storage unit (501) is reinjected via a mixer (601) into the compressed air stream (30) to form a stream (32). Stream (32) is heated in a medium-pressure heat storage and recovery unit (201), which releases the heat stored during the compression phase, until stream (33) reaches a temperature of 255°C. This heated compressed air stream (33) expands in a medium-pressure turbine (701) and generates electricity via a generator until it reaches a pressure of 5 bar (0.5 MPa) and a temperature of 70°C (34) at its outlet. A stream (35) of condensate at a pressure of 6 bar (0.6 MPa) and a temperature of 50°C from a liquid storage unit (500) is reinjected into the compressed air stream (34) via a mixer (600) to form stream (36). Stream (36) is heated in a low-pressure heat storage and recovery unit (200), which releases the heat stored during the compression phase, until stream (37) reaches a temperature of 245°C. The hot compressed air stream (37) expands in the low-pressure turbine (702) and generates electricity via a generator until it reaches a pressure of 1.02 bar (0.102 MPa) and a temperature of 80°C (38) at the outlet.

[0165] For a compressor power consumption of 100MW, the efficiency of the energy storage process is 70.4%. The total condensate flow rate in the three compression stages is 7.5 tons / hour. The heat storage capacity is 93MWth, and the required cooling capacity is 14.6MWth.

[0166] Therefore, the reinjection of condensate, by increasing the flow rate through the turbine during expansion, allows for an increase in process efficiency of about 1% and a reduction in the required cooling capacity of about 30% compared to Example 1 not according to the invention.

[0167] Example 4 according to the present invention

[0168] This example implements according to Figure 7 The system and method of the present invention are shown as embodiments.

[0169] During the compression phase (1), an external airflow (10) with a pressure of 1.02 bar (0.102 MPa), a temperature of 27°C, and a humidity of 14.6 g water / kg air is compressed by a low-pressure compressor (100) and exits (11) at a temperature of 255°C and a pressure of 6 bar (0.6 MPa). The flow (11) is sent to a low-pressure heat storage and recovery unit (200), which cools the air to a temperature of 80°C (12) and stores the heat energy until the expansion phase (2). The flow (12) is cooled again to a temperature of 50°C by a cooling unit (300) at the outlet (13). The flow (13) then consists of water and air from the humidity of the air, which condenses in (200) and / or (300) during the cooling phase. The condensate (14) is separated from the flow in the compression line (1) in a gas / liquid separator (400) operating at the pressure of the flow (13), and then sent to a liquid storage device (500) at a maintained pressure of 6 bar (0.6 MPa). The flow (15), which is again completely gaseous, is compressed by a medium-pressure compressor (101) and leaves (16) at a temperature of 275°C and a pressure of 28 bar (2.8 MPa). The flow (16) is sent to a medium-pressure heat storage and recovery device (201), which cools the air to a temperature of 82°C (17) and stores the heat energy until the expansion phase (2). The flow (17) is cooled again by a cooling device (301) until it reaches a temperature of 50°C at the outlet (18). The flow (18) then consists of water and air with humidity from the air, and condenses in (201) and / or (301) during the cooling phase. The condensate (19) is separated from the air stream (20) in a gas / liquid separator (401) operating at the same pressure as the air stream (18), and then sent to a liquid storage device (501) at a maintained pressure of 28 bar (2.8 MPa). The stream (20), now entirely gaseous, is compressed by a high-pressure compressor (102) and flows out from the high-pressure compressor (21) at a temperature of 250°C and a pressure of 117 bar (11.7 MPa). The stream (21) is sent to a high-pressure heat storage and recovery device (202), which cools the air to a temperature of 80°C (22) and stores the heat energy until the expansion phase (2). The stream (22) is cooled again by a cooling device (302) until it reaches a temperature of 30°C (23) at the outlet, which is the air storage temperature. The stream (23) then consists of water and air with humidity from the air, which condenses in (202) and / or (302) during the cooling phase. The condensate (24) is separated from the gas flow (25) in a gas / liquid separator (402) operating at the same pressure as the gas flow (23), and then sent to the liquid storage device (502) at a maintained pressure of 117 bar (11.7 MPa).

[0170] Then, a compressed air stream (25) with a pressure of 117 bar (11.7 MPa) and a temperature of 30°C is sent to the compressed air storage device (1000) until the energy recovery stage (2).

[0171] When power generation is required, a stream (27) of condensate (117 bar, 11.7 MPa) at a temperature of 30°C from a liquid storage unit (502) is re-injected via a mixer (600) into a stream (26) of compressed air leaving the compressed air storage unit (1000) to form a stream (28). The stream (28) is preheated in an additional heat exchanger (800) to reach a temperature (29) of 70°C at the outlet. The stream (29) is then heated in a high-pressure heat storage and recovery unit (202), which releases the heat stored during the compression phase, until the stream (30) reaches a temperature of 240°C. This heated compressed air stream (30) expands in a high-pressure turbine (700) and generates electricity via a generator until it reaches a pressure of 28 bar (2.8 MPa) and a temperature of 85°C (31) at the outlet. A stream (32) of condensate (28 bar, 2.8 MPa) at a temperature of 50°C from a liquid storage unit (501) is reinjected into a compressed air stream (30) via a mixer (601) to form stream (33). Stream (33) is heated in a medium-pressure heat storage and recovery unit (201) that releases the heat stored during the compression phase until stream (34) reaches a temperature of 255°C. This heated compressed air stream (34) expands in a medium-pressure turbine (701) and generates electricity via a generator until it reaches a pressure of 5 bar (0.5 MPa) and a temperature of 70°C (35) at the outlet. A stream (36) of condensate (6 bar, 0.6 MPa) at a temperature of 50°C from a liquid storage unit (500) is reinjected into a compressed air stream (35) via a mixer (602) to form stream (37). The stream (37) is heated in a low-pressure heat storage and recovery unit (200), which releases the heat stored during the compression phase until the stream (38) reaches a temperature of 245°C. The heated compressed air stream (38) expands in a low-pressure turbine (702) and generates electricity via a generator until it reaches a pressure of 1.02 bar (0.102 MPa) and a temperature of 80°C (39) at the outlet.

[0172] The stream (39) is then sent to a heat exchanger (800) to generate its energy into the stream (28). The resulting stream (40) exits the exchanger at 35°C.

[0173] For a compressor power consumption of 100.0 MW, the energy storage process efficiency is 70.2%. The total condensate flow rate in the three compression stages is 7.5 tons / hour. The heat storage capacity is 85.7 MWth, and the required cooling capacity is 21.8 MWth. Compared to Example 1, this configuration also allows for a 21% reduction in the size of the high-pressure heat storage and recovery unit.

[0174] Example 5 according to the invention

[0175] This example implements according to Figure 8 The system and method of the present invention, as shown in Example 3, were evaluated for operational status and efficiency.

[0176] For a compressor power consumption of 100.0 MW, the efficiency of the energy storage system and method is 70.0%. The total condensate flow rate in the three compression stages is 7.5 tons / hour. The heat storage capacity is 85.7 MWth, and the required cooling capacity is 21.8 MWth. Compared to Example 3, this configuration also allows for a 18% reduction in the size of the high-pressure heat storage and recovery unit (202) and a 3% reduction in the size of the medium-pressure heat storage and recovery unit (201). Compared to Example 1, this configuration allows for a 16% reduction in the size of the high-pressure heat storage and recovery unit (202).

[0177] Therefore, Examples 2 to 4 show that the system and method according to the invention allow for increased performance of the method while limiting the power required for cooling, and for some embodiments, allow for increased performance of the method while limiting the size of the heat storage and recovery device.

Claims

1. A compressed gas energy storage and recovery system, comprising: - A gas compression pipeline (1) having at least two continuous compression stages (3), each of the compression stages (3) including a compression device (100, 101, 102) and a heat storage and recovery device (200, 201, 202) arranged downstream of the compression device (100, 101, 102) in the direction of gas flow. - At least one compressed gas storage device (1000) is arranged at the outlet of the gas compression pipeline (1) for storing the compressed gas. - A gas expansion line (2) for expanding the compressed gas stored in the compressed gas storage device (1000), the gas expansion line (2) comprising at least two consecutive expansion stages (4), each expansion stage (4) comprising an expansion device (700, 701, 702) and a conduit configured to circulate the compressed gas in at least one of the heat storage and recovery devices (200, 201, 202) of the compression stage (3), thereby heating the compressed gas. The feature is that the heat storage and recovery device (200, 201, 202) includes heat storage particles for heat exchange through direct contact between the gas and the heat storage particles, the material being retained in the heat storage and recovery device, and each expansion stage (4) includes a liquid delivery device (600, 601, 602), the liquid delivery device (600, 601, 602) being positioned upstream of the heat storage device (200, 201, 202) in the direction of gas flow. Each of the compression stages (3) includes a device (400, 401, 402) for separating the gas and liquid, and The system includes multiple liquid storage devices (500, 501, 502) for storing the liquid at the outlet of the device (400, 401, 402) for separating the gas and liquid, and the delivery device (600, 601, 602) for delivering the liquid from the liquid storage devices (500, 501, 502).

2. The system according to claim 1, characterized in that, For each of the compression stages, the gas and liquid separation devices (400, 401, 402) are arranged downstream of the heat storage and recovery devices (200, 201, 202) in the direction of gas flow.

3. The system according to claim 1 or 2, characterized in that, The compression stage (3) included in the compression line (1) is as numerous as the expansion stage (4) included in the expansion line (2), and each heat storage and recovery device (200, 201, 202) of the compression stage (3) is used for the corresponding expansion stage (4).

4. The system according to claim 3, characterized in that, The compression line (1) and the expansion line (2) each comprise three stages.

5. The system according to claim 1 or 2, characterized in that, At least one compression stage (3) includes a cooling device (300, 301, 302) downstream of the heat storage and recovery device (200, 201, 202) in the direction of gas flow.

6. The system according to claim 5, characterized in that, The cooling devices (300, 301, 302) include air coolers.

7. The system according to claim 1 or 2, characterized in that, The expansion line includes at least one additional heat exchange device (800, 801) located between the gas and the compressed gas at the outlet of the expansion line.

8. The system according to claim 7, characterized in that, The at least one additional heat exchange device (800, 801) is arranged in the first expansion stage in the direction of gas flow.

9. The system according to claim 7, characterized in that, The expansion line (2) includes two additional heat exchange units (800, 801) arranged in the two expansion stages.

10. The system according to claim 7, characterized in that, The at least one additional heat exchange device (800, 801) is arranged in the direction of gas flow between the delivery device (600, 601, 602) for the liquid and the heat storage and recovery device (200, 201, 202).

11. A method for storing and recovering compressed gas energy, comprising at least the following steps: -In the energy storage phase: a) The gas is continuously compressed at least twice in a compression line (1) comprising at least two compression stages (3), each compression stage (3) comprising at least one compression device (100, 101, 102). b) After each compression step, the heat of the compressed gas is recovered in at least one heat storage and recovery device (200, 201, 202). c) The cooled compressed gas is stored in at least one compressed gas storage device (1000). -In the energy recovery phase: d) The compressed gas leaving the compressed gas storage device (1000) is circulated in an expansion line (2) comprising at least two consecutive expansion stages (4), and in each expansion stage (4), the compressed gas is heated by circulating it in one of the heat storage and recovery devices (200, 201, 202) using the heat stored during the compression step, and then the heated compressed gas is expanded in the expansion device (700, 701, 702). The feature is that heat is stored in the heat storage particles through heat exchange occurring via direct contact between the gas and the material of the heat storage particles retained in the heat storage and recovery device, and that liquid is fed into the compressed gas before each expansion step and before the step of heating the gas. In this process, after each compression step, the gas and the liquid present in the gas are separated, and The device (200, 201, 202) that performs as many compression steps as the expansion step and is used to store and recover heat in each step b) is used to heat the compressed gas in the corresponding expansion step.

12. The method according to claim 11, characterized in that, The separated liquid is stored, and the liquid fed into the compressed gas is the stored liquid.

13. The method according to claim 11 or 12, characterized in that, After each heat recovery step, before sending the gas to the next compression step or to the compressed gas storage device (1000), the compressed gas at the outlet of the heat storage and recovery device (200, 201, 202) is cooled in the cooling device (300, 301, 302).

14. The method according to claim 11 or 12, characterized in that, Prior to at least one expansion step, the gas is heated at the outlet of the expansion line by at least one additional heat exchange with the gas.

15. The method according to claim 14, characterized in that, In the direction of gas flow, at least one additional heat exchange is performed for the first expansion step.

16. The method according to claim 14, characterized in that, Two additional heat exchanges are performed for the two expansion steps.

17. The method according to claim 14, characterized in that, The additional heat exchange is performed after the step of feeding the stored liquid into the compressed gas.

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