WO2022117407A1 - System and method for storing and recovering energy via compressed gas with a rankine cycle - Google Patents

Abstract

A system for storing and recovering energy via compressed gas, comprising: • -a gas compression line (1) comprising at least one compression means (100, 101, 102); • -at least one compressed-gas storage means (1000); • -a gas expansion line (2) comprising at least one expansion means (700, 701, 702); • -at least one Rankine cycle between the compressed-gas storage means (1000), the outlet flow (26) of which constitutes the cold source, and the expansion means (702), the outlet flow (39) of which constitutes the hot source.

Description

GAS ENERGY STORAGE AND RECOVERY SYSTEM AND METHOD

TABLET WITH RANKINE CYCLE

Technical area

The present invention relates to the field of storage and production of energy by compression and expansion of gas, in particular air.

While global energy goals aim to favor renewable energies over fossil fuels and to gradually increase their proportion in the energy mix, their variable nature remains their major drawback. To address this problem, energy storage appears to be the ideal solution. By storing the surplus electricity produced at the peak of production in order to have it available when it falls below demand, storage makes it possible to overcome the constraint of variability and provides continuity, or at least flexibility. , basically non-existent, to renewable energies. Thus, the need for an energy storage process exists and will grow with the proportion of this type of energy in the global energy mix.

Many mature storage technologies already exist today, such as mechanical storage such as Pumped Energy Transfer Stations (STEP) 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 sent back to the lower reservoir via a hydraulic turbine which will then generate electricity via an alternator. Hydroelectric dams also work 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 generators producing electricity. Compressed air energy storage (CAES) technology is one of the mechanical solutions. Other electrochemical type technologies can also be used for energy storage such as lithium-ion, lead-acid or even nickel-cadmium batteries, or circulation batteries using electrolytes.

Compressed Air Energy Storage (CAES) is a mature technology with the first installation built in Germany in the late 1970s, producing 290 MW. The principle of CAES is to use the electricity produced and not consumed to compress air. In order to avoid any damage to the compressors, the heat resulting from the compression is evacuated between each stage. Air compressed at medium or high pressure (40 bar to 300 bar, i.e. 4 to 30 MPa) is sent to a natural type storage such as a salt cave, a mine (salt, limestone, coal) or even to a artificial storage pending the phase energy discharge. During the electricity production phase, the stored air is extracted from the storage in order to be expanded in turboalternators. For the basic CAES system such as that established in the late 1970s, compressed air was used to power gas turbines (also called combustion turbines). These turbines burn via a natural gas combustion chamber in the presence of compressed air to produce very hot combustion gases (500°C-800°C), expanded to produce electricity. The CAES process has an energy yield of around 50%.

Prior technique

A variant of CAES is the adiabatic process or ACAES (from the English “adiabatic compressed air energy storage”). The main difference with the original CAES is that the heat resulting from the compression is no longer evacuated between each stage, but stored in order to be able to heat the air upstream of the turbines during the electricity production phase. Thanks to this reuse of the thermal energy internal to the process, the efficiency of the ACAES reaches around 70%. The cooling of the air in the compression phase can be done via an indirect contact exchange in a heat exchanger with a heat transfer fluid. The hot heat transfer fluid is then stored and insulated as much as possible thermally in order to be able to transfer its heat to the air during the expansion phase. It can also be carried out via an exchange in direct contact between the air and a thermal storage mass operating by sensible heat or thanks to phase change materials. In both cases, the heat from the air will be stored directly in the mass, either within the material, or by performing a phase change in the material. During the expansion phase, the cold air is reinjected into the thermal storage mass and by direct contact, the air will heat up by capturing the heat of the material or allowing the reverse phase change releasing this heat. This cooling of the air can then induce water condensation if the air has a certain humidity. This condensed water must then be extracted from the air circuit in order not to damage the compressors downstream.

The document CN105569753B discloses an ACAES process in which an Organic Rankine Cycle (ORC) is associated during the expansion phase and for which the hot source is ensured by the waste heat of the thermal energy used to preheat the air upstream of the turbine, and where the cold source is provided by the expanded air flow from the turbine.

The document FR3074846A1 discloses an ACAES process in which an Organic Rankine Cycle (ORC) is associated during the expansion phase and for which the hot source is ensured by the waste heat of the thermal energy used to preheat the air upstream of the turbines. The document WO16079485A1 discloses an ACAES process in which the thermal energy resulting from the compression phase is used within an Organic Rankine Cycle (ORC) to heat the working fluid. Said Rankine Cycle therefore only works during the compression phase.

The object of the present invention is to improve the performance of an ACAES-type adiabatic compressed gas energy storage process by associating it with at least one Rankine cycle, for example an Organic Rankine cycle (ORC), energy producer, in which the use of the hot source and the cold source make it possible to use the waste heat of the process or even to improve the process.

Summary of the invention

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

-A gas compression line (1) with at least one compression stage (3), each compression stage (3) comprising compression means (100, 101, 102) and means for storing and recovering the heat (200, 201, 202) arranged downstream of said compression means (100, 101, 102), in the direction of circulation of said gas,

-At least one compressed gas storage means (1000) arranged at the outlet of said gas compression line (1) to store said compressed gas,

-A gas expansion line (2) for expanding said compressed gas stored in said compressed gas storage means (1000), said gas expansion line (2) comprising at least one expansion stage (4), each stage expansion (4) comprising expansion means (700, 701, 702) and conduits configured to circulate said compressed gas in at least one of said heat storage and recovery means (200, 201, 202) of said stages compression (3) so as to heat said compressed gas,

- At least one Rankine cycle comprising an expansion turbine (703), a condenser (800), a pump (900) and an evaporator (801), and pipes configured to circulate a working fluid adapting to the temperatures involved in said Rankine cycle, to produce an additional quantity of energy on expansion, and arranged between said compressed gas storage means (1000) whose output flow (26), optionally mixed with a liquid, constitutes the cold source and said expansion means (702) whose outlet flow (39) constitutes the hot source in the direction of circulation of said gas.

Each expansion stage (4) may comprise means for introducing a liquid (600, 601, 602), said means for introducing said liquid (600, 601, 602) being provided upstream, in the direction of circulation said gas, said heat storage means (200, 201, 202) and said Rankine cycle being arranged between said means for introducing said liquid (600) whose outlet stream (28) constitutes the cold source and said expansion means (702) whose outlet stream (39) constitutes the hot source in the direction of circulation of said gas.

Preferably, said heat storage and recovery means (200, 201, 202) comprise heat storage particles.

Each compression stage (3) may include means for separating said gas and a liquid (400, 401, 402).

For each compression stage, said gas and liquid separation means (400, 401, 402) can be arranged downstream of said heat storage and recovery means (200, 201, 202), in the direction of circulation. of said gas.

Said system may comprise a plurality of liquid storage means (500, 501, 502) for storing said liquid at the outlet of said gas and liquid separation means (400, 401, 402), and said introduction means (600 , 601, 602) can introduce said liquid from said liquid storage means (500, 501, 502).

In one embodiment, said compression line (1) comprises as many compression stages (3) as the expansion line (2) comprises expansion stages (4), each means for storing and recovering the heat (200, 201, 202) of a compression stage (3) being used in the corresponding expansion stage (4).

Said compression line (1) and said expansion line (2) may comprise three stages respectively.

At least one compression stage (3) may include cooling means (300, 301, 302) downstream of the heat storage and recovery means (200, 201, 202), in the direction of circulation of said gas, preferably, said cooling means (300, 301, 302) comprising an air cooler or heat exchangers exchanging with a coolant.

The system may include a second Rankine cycle comprising an expander (704), a condenser (802), a pump (901) and an evaporator (803), and lines configured to circulate a working fluid adapting at the temperatures involved in said second Rankine cycle, said second Rankine cycle being arranged between two liquid storage means (503) and (504), said liquid storage means (503) collecting the output flows of the heat transfer fluid of said cooling means and said liquid storage means (504) distributing the inflows of heat transfer fluid from said cooling means, the hot source of said second Rankine cycle being the heat transfer fluid from said cooling means (300, 301, 302 ) stored in the liquid storage means (503) and the cold source of said second cycle being an external flow of cooling liquid, preferably water (49). The working fluid of said one or more Rankine cycle(s) can be chosen from among propane, butane or any other coolant adapting to the temperatures involved in said Rankine cycle.

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

- In the energy storage phase: a) a gas is successively compressed at least once in a compression line (1) comprising at least one compression stage (3), each compression stage (3) comprising at least one compression means (100, 101, 102); b) after each compression step, the heat of said compressed gas is recovered in at least one heat storage and recovery means (200, 201, 202); c) said cooled compressed gas is stored in at least one compressed gas storage means (1000);

- In the energy recovery phase: d) the compressed gas leaving the compressed gas storage means (1000) is circulated in an expansion line (2) comprising at least one expansion stage (4), and in each expansion stage (4), the compressed gas is heated by circulating it in one of said heat storage and recovery means (200, 201, 202) using the heat stored during the compression stage and then expanded the compressed gas heated in an expansion means (700, 701, 702); e) an additional quantity of energy is produced on expansion, by means of at least one Rankine cycle comprising an expansion turbine (703), a condenser (800), a pump (900) and an evaporator (801) , the flow of gas leaving the low pressure turbine (702) being used as a heat source within the evaporator (801) to evaporate the working fluid of said Rankine cycle before its expansion in the expansion turbine (703) and the flow composed of compressed gas leaving the compressed gas storage means (1000) or the flow consisting of compressed gas and liquid coming from the mixer (600) being used as a cold source within the condenser (800) to condense the fluid work of said Rankine cycle before its compression in the pump (900).

Advantageously, the heat is stored in heat storage particles. After each compression step, said gas and a liquid present in said gas can be separated.

Said separated liquid can be stored, and said liquid introduced into said compressed gas is said stored liquid.

As many compression steps as expansion steps can be carried out, and the heat storage and recovery means (200, 201, 202) of each of the steps b) are used to heat the compressed gas from the corresponding relaxation step. In one embodiment, after each heat recovery step, the compressed gas is cooled at the outlet of the heat storage and recovery means (200, 201, 202) in a cooling means (300, 301, 302 ) before the gas is sent to the next compression stage or to the compressed gas storage means (1000).

In a variant of this embodiment, an additional quantity of expansion energy can be produced by means of a second Rankine cycle comprising an expansion turbine (704), a condenser (802), a pump (901) and an evaporator (803), arranged between a liquid storage means (503) making it possible to collect the hot heat transfer fluid at the outlet of said cooling means (300, 301, 302) and a liquid storage means (504) making it possible to supply cold heat transfer fluid said cooling means (300, 301, 302), the flow of hot heat transfer fluid from said cooling means (300, 301, 302) being used as a heat source within the evaporator (803) to evaporate the working fluid of said Rankine cycle before its expansion in the expansion turbine (704); an external flow of cooling liquid (49), preferably water, being used as a cold source within the condenser (802) to condense the working fluid of said second Rankine cycle before its compression in the pump (901) ; and the cooled coolant flow exiting the evaporator (803) being stored in said liquid storage means (504).

Other characteristics and advantages of the system and of the method according to the invention will appear on reading the description below of non-limiting examples of embodiments, with reference to the appended figures and described below.

List of Figures

Figure 1 illustrates the general operation of a Rankine cycle as implemented in the system and the method according to the invention.

Figure 2 illustrates an adiabatic, non-Rankine cycle compressed gas energy storage and recovery system and process.

FIG. 3 illustrates a system and a method for storing and recovering energy by compressed gas including a Rankine cycle according to the invention, in its various variants. FIG. 4 illustrates a system and method for storing and recovering energy by compressed gas in one embodiment including a second Rankine cycle located between the coolant fluid inlets and outlets of the cooling means.

Description of embodiments

The present invention relates to a system and a method for storing and recovering energy by compressed gas, implementing at least one Rankine cycle, preferably an Organic Rankine Cycle (ORC).

In the present invention the terms "upstream", "downstream", "input", "output", "before", "after" are defined by the direction of circulation of the gas, respectively during the energy storage phase (compression phase), and during the energy recovery phase (relaxation phase).

The Rankine cycle is a thermodynamic cycle which notably makes it possible to convert heat into another energy, for example electrical energy or mechanical energy. A Rankine cycle (Figure 1) is a cycle in which a working fluid circulating in a closed circuit CF is successively subjected to the following stages:

- vaporization, for example by means of a so-called evaporator exchanger (801) with a hot source C,

- expansion, by means of expansion of the working fluid, for example a turbine (703), which converts thermal energy into mechanical energy, or even into electrical energy,

- condensation, for example by means of a so-called condenser exchanger (800) which exchanges negative calories with a cold source F, and

- compression and circulation, for example by means of a pump (900).

The closed circuit operating according to the Rankine cycle further comprises conduits for connecting the various components of the closed circuit. The working fluid can be any refrigerant adapting to the temperatures involved in the Rankine cycle. By Organic Rankine Cycle (ORC) is meant a Rankine Cycle in which the working fluid is an organic compound, for example propane, butane, or any other organic refrigerant fluid adapting to the temperatures involved in the Cycle. Organic Rankine.

The system according to the invention comprises:

- a compression line (referred to as a "compression line", the gas line going from the gas inlet to the compressed gas storage means passing through at least one compression means), with at least one stage of compression (said successive stages being in series when there are several), each compression stage comprises: - a means of compressing the gas (compressor), making it possible to increase the pressure of the gas, with a view to its storage, the means of compression can be axial compressors, centrifugal, or any other technology,

- a heat storage and recovery means arranged downstream of the compression means, in order to store the heat generated by the compression, and to reduce the temperature of the gas before the next compression stage or before the storage means of compressed gas,

- at least one compressed gas storage means, for storing the compressed gas at the outlet of the compression line in order to reuse it later, the compressed gas storage means possibly being a natural cavity such as a saline cavity, an old mine or an aquifer or artificial storage;

a gas expansion line (referred to as the "expansion line", the gas line going from the compressed gas storage means to the gas outlet passing through at least one expansion means) with at least one expansion stage (the successive stages being in series when there are several of them), each expansion stage comprises at least one means for expanding the compressed gas to generate energy, for example a turbine that can be coupled to an alternator, pipes to make circulating the gas in one of the storage means of the compression line, so as to recover the stored heat and to increase the temperature of the gas to increase the energy produced in the expansion means.

- at least one Rankine cycle arranged in parallel with the expansion line in order to recover the fatal heat resulting from the expansion and to produce additional energy.

According to the invention, the heat storage and recovery means advantageously comprise heat storage particles. Thus, the heat exchange is carried out by direct exchange between the gas and a material, the material remaining in the heat storage and recovery means. In other words, there is no circulation of heat-storage particles. Consequently, it is not necessary to have a dedicated system which comprises storage tanks for a heat transfer fluid, pumping means, and dedicated pipes. For example, the material can be stones, concrete, gravel, balls of phase change material (PCM) optionally encapsulated, preferably with a solid-liquid phase change, zeolites, or any similar material allowing the exchange and storage of heat at the temperatures involved by the compressed gas (preferably air).

In addition, each expansion stage may include a means for introducing a liquid. The liquid introduction means allows mixing between the gas from the expansion line and the liquid. Thus, thanks to the injection of the liquid (for example water), the gas flow can be increased in each expansion stage, which makes it possible to increase the efficiency of the system and process. The means for introducing and mixing the liquid are provided in the expansion line upstream of the heat storage means, in this way, the gas and liquid mixture (preferably air and water) reinjected is reheated in the storage means heat, which makes it possible to vaporize the liquid, and in this way only a gas is led into the expansion means.

According to one embodiment of the invention, the gas may be air. This may be air taken from the ambient environment. Alternatively, it may include other gases.

According to one aspect of the invention, the liquid is water. This may be in particular the humidity present in the gas, in particular when the gas is air from the ambient environment. Alternatively, it may include other liquids.

Additionally, at least one compression stage may include cooling means. This cooling means can be arranged downstream of the heat storage and recovery means. This cooling means makes it possible to cool the gas more significantly, which makes it possible to reduce the dimensions of the means for storing and recovering the heat. These heat cooling means can be air coolers or heat exchangers (tubes/shell, plates, spirals or other suitable technologies) exchanging with a heat transfer fluid which can be water, propane, butane or any other refrigerant suitable for the necessary cooling. The cooling means can be adapted to the pressure of the air entering and exchanging with each of them.

According to one embodiment, each compression stage may comprise a gas/liquid separation means, which makes it possible to extract the liquid present in the gas, in particular due to the condensation of the water present in the gas, and making it possible to eliminate traces of liquid which could be contained in the gas after it has cooled and which could damage the system, in particular the compression means.

In this embodiment, the gas/liquid separation means can be arranged downstream of the cooling means. In this way, it is possible to extract the liquid formed by condensation in the heat storage and recovery means as well as in the cooling means.

Additionally, the system may include liquid storage means to store liquid extracted from the compression line. For example, a liquid storage means may be provided per compression stage (therefore per gas-liquid separation means). Thus, the liquid can be stored at different pressures. Advantageously, the liquid introduction means can allow the introduction of liquid leaving the liquid storage means, thus making possible the use of liquid recovered from condensation, in the compression line. According to one embodiment of the invention, the gas/liquid separation means can be arranged downstream of the heat storage and recovery means or downstream of the cooling means. In this way, it is possible to extract the liquid formed by condensation in the heat storage and recovery means.

Alternatively, the gas/liquid separation means can be arranged upstream of the compression means, or between the compression means and the heat storage and recovery means.

Advantageously, the compression line and the expansion line can comprise as many stages. 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 exchange in the heat storage and recovery means, and which allows in particular a reinjection of the liquid into an expansion stage which corresponds to the compression stage in terms of pressure. Thus, the system and method are simplified.

For this embodiment, the number of compression and expansion stages can be between two and six, preferably between three and five. For example, the number of compression and expansion stages can be three, which allows good management of temperatures and pressures, while maintaining a simple design.

Alternatively, the number of compression stages and the number of expansion stages may be different. For this embodiment, provision may be made to pool at least part of the heat storage and recovery means, as well as at least part of the liquid introduction means.

The expansion line comprises according to the invention at least one means for recovering additional heat and producing additional energy, in the form of a Rankine cycle arranged in parallel with said expansion line, said Rankine cycle implementing two heat exchange means: a means for heating, in which the heat of the gas leaving the expansion line exchanges with the working fluid of said Rankine cycle, and a means for cooling, in which the gas leaving the air storage exchanges with the working fluid of said Rankine cycle.

Said at least one Rankine cycle is arranged in an expansion stage comprised between the first and the last expansion stage. In other words, the means for cooling the working fluid is arranged in an expansion stage between the first and the last expansion stage. The term "first expansion stage" refers to the first expansion stage through which the gas passes in the expansion line. In other words, the first expansion stage is close to the compressed gas storage means. Thus, the heat of the gas leaving the line of expansion is used to heat up the working fluid of the Rankine cycle. Preferably, the means for cooling the working fluid can be arranged in the first expansion stage.

In one embodiment, the system according to the invention may comprise a second Rankine cycle arranged between the coolant fluid inlets and outlets of the cooling means, more precisely between at least one liquid storage means collecting the coolant fluid flows at the outlet of said cooling means and at least one liquid storage means distributing the heat transfer fluid flows at the inlet of said cooling means. Said second Rankine cycle comprises an expansion turbine, a condenser, a pump, and an evaporator, and pipes configured to circulate a working fluid adapting to the temperatures involved in said second Rankine cycle. Thus, additional energy can be recovered from the compressed gas energy storage and recovery system and process.

The hot source of said second Rankine cycle is the hot heat transfer fluid from said cooling means and the cold source of said second Rankine cycle is an external flow of cooling liquid, preferably water.

The working fluid can be the same or different for each of the Rankine cycles.

Furthermore, the invention relates to a method for storing and recovering energy by compressed gas.

The method according to the invention implements the following steps:

- In the energy storage phase (compression phase): a) a gas is successively compressed at least once in a compression line comprising at least one compression stage, each compression stage comprising at least one compression means; b) after each compression step, the heat of the compressed gas is recovered in at least one heat storage and recovery means, c) the compressed gas cooled at the outlet of the compression line is stored in a heat storage means compressed gas;

- In the energy recovery phase (expansion phase): d) the compressed gas leaving the compressed gas storage means is circulated in an expansion line comprising at least one expansion stage, and in each expansion stage, the compressed gas is heated by circulating it in one of the means for storing and recovering the heat thanks to the heat stored during the compression step and then the heated compressed gas is expanded in an expansion means; e) an additional quantity of energy (for example electrical, hydraulic or pneumatic) is produced on expansion, by means of a Rankine cycle, the flow of gas leaving the turbine being used as a heat source within an evaporator to evaporate the working fluid of said Rankine cycle before its expansion in an expansion turbine and the flow composed of compressed gas at the outlet of the compressed gas storage means or the flow composed compressed gas and liquid from a gas-liquid mixer being used as a cold source within a condenser to condense the working fluid of said Rankine cycle before its compression in the pump.

The implementation of the Rankine cycle in the process according to the invention also makes it possible to recover part of the fatal heat of the expansion, which would be lost.

In addition, according to the invention, advantageously, the heat is stored and recovered in heat storage particles. In other words, the heat storage and recovery means advantageously comprise heat storage particles. Thus, the heat exchange is carried out by direct exchange between the gas and a material, the material remaining in the heat storage and recovery means. In other words, there is no circulation of heat-storage particles. Consequently, it is not necessary to have a dedicated system which comprises storage tanks for a heat transfer fluid, pumping means, and dedicated pipes. For example, the material can be stones, concrete, gravel, beads of phase change material (PCM), zeolites, or any similar material.

In addition, before each expansion step, a liquid can be introduced and mixed in the compressed gas before the gas heating step. For this purpose, each expansion stage may comprise a means of introducing and mixing the liquid, thus making it possible to use the liquid recovered from condensation, in the compression line. Thus, thanks to the injection of liquid, the gas flow is increased in each expansion stage, which makes it possible to increase the efficiency of the system and the process. The means for introducing and mixing the liquid are provided in the expansion line upstream of the heat storage means, in this way the injected gas and liquid mixture is heated in the heat storage means, which allows to vaporize the liquid, and in this way only a gas is led into the expansion means.

Preferably, the compressed gas energy storage and recovery method can implement the compressed gas energy storage and recovery system according to any one of the variants or combinations of variants as described below. above.

According to one embodiment of the invention, the gas may be air. This may be air taken from the ambient environment.

According to one aspect of the invention, the liquid can be water. It may be in particular the humidity present in the gas, in particular when the gas is air. According to one embodiment of the invention, after each compression step, the gas and a liquid present in the gas can be separated.

Further, the method may include a liquid storage step to store liquid extracted from the compression line. For example, a liquid storage means may be provided per compression stage (therefore per gas-liquid separation stage). Thus, the liquid can be stored at different pressures. Advantageously, the liquid introduced into the gas is the liquid resulting from the storage step, thus making it possible to use liquid recovered from condensation, in the compression line.

According to one embodiment of the invention, the gas/liquid separation step can be carried out after the heat storage step. In this way, it is possible to extract the liquid formed by condensation in the heat storage and recovery means.

Advantageously, as many compression steps as expansion steps can be carried out. In this case, the compression line and the expansion line can comprise as many stages. 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 exchange in the heat storage and recovery means, and which allows a reinjection of the liquid into an expansion stage which corresponds to the corresponding compression stage. Thus, the system and method are simplified.

For this embodiment, the number of compression and expansion stages can be between one and six, preferably between three and five. For example, the number of compression and expansion stages can be three, which allows good management of temperatures and pressures, while maintaining a simple design.

Alternatively, the number of compression stages and the number of expansion stages may be different. For this embodiment, provision may be made to pool at least part of the heat storage and recovery means, as well as at least part of the liquid introduction means.

In addition, the energy storage phase can include at least one cooling step in one of the compression stages. This cooling step can be carried out after the heat storage step by a cooling means. This cooling step makes it possible to cool the gas more significantly, which makes it possible to reduce the dimensions of the means for storing and recovering the heat. These cooling means can be air coolers or heat exchangers (tubes/shell, plates, spirals or other suitable technologies) exchanging with a heat transfer fluid which can be water, propane, butane or any other refrigerant suitable for the necessary cooling. The cooling means can be adapted to the pressure of the air entering and exchanging with each of them.

For this embodiment, the gas/liquid separation step can be carried out after the cooling step. In this way, it is possible to extract the liquid formed by condensation in the heat storage and recovery means as well as in the cooling stage.

According to the invention, the energy recovery phase comprises at least two stages of complementary heat exchange, a first between the gas at the outlet of the expansion line and the working fluid of said at least one Rankine cycle and a second between the compressed gas and the working fluid of the Rankine cycle.

Thus, in said at least one Rankine cycle, the hot gas at the outlet of the expansion line acts as a hot source, while the compressed gas in the expansion line, optionally mixed with a liquid (for example liquid condensed during the compression phase), plays the role of the cold source. In this way, it is possible to recover lost thermal energy, and thus valorize the waste heat resulting from the process in order to improve its efficiency. More precisely, at the outlet of the expansion line turbine, the hot gas at the outlet of the expansion line is sent to a first heat exchanger (evaporator) in order to vaporize the working fluid of the Rankine cycle. Once vaporized, the working fluid is sent to the Rankine cycle expansion turbine which will produce additional energy (for example electrical, pneumatic or hydraulic) to that produced by the compressed gas expansion line, via a alternator for electric power example. At the outlet of the Rankine cycle expansion turbine, the working fluid has seen its pressure decrease as well as its temperature, but remains mainly in vapor form. The working fluid is sent to a second heat exchanger (condenser) of the Rankine cycle in order to be condensed there. Once condensed, the working fluid is sent to the Rankine cycle pump to increase its pressure.

According to a variant of the embodiment of the invention in which one or more cooling means are present in the compression line, it is possible to integrate into the system according to the invention a second Rankine Cycle, in which the source hot is the heat transfer fluid, preferably water, from the cooling means or means, and whose cold source is a flow of external cooling liquid, preferably cooling water, for example from a river, network or any other source of cold water.

Description of figures

Figure 1 previously described illustrates the operation of a Rankine cycle. Figure 2 illustrates, schematically and in a non-limiting manner, a system and a conventional ACAES method for storing and recovering energy by compressed gas (in this case air).

The flows and steps are detailed below respectively for the electricity storage phase and for the electricity production phase, in the case where the gas is humid air.

Electricity storage phase

The humid air at atmospheric pressure from the external environment (10) is compressed via a first low pressure compression means (100) which increases the flow temperature at the compression outlet (11) to a temperature between 200° C. and 400°C. The air is then cooled in a heat storage and recovery means (low pressure direct contact (200) until it reaches an outlet temperature (12) between 100°C and 50°C. The heat exchanged is stored directly in the heat storage and recovery means (200).The air can then be sent to an additional cooling means (300) to reach, for example, an outlet temperature (13) less than or equal to 50° C. Some of the moisture in the air condenses during cooling under pressure.The condensed water (14) can then be separated from the air stream (15) in a gas-liquid separator (400) operating at the pressure and temperature of the inlet stream (13) and sent to a storage tank (500).The air separated from the condensed water (15) is compressed via a second medium pressure compressor (101) until it reaches a temperature at the compression outlet (16) between 200° C. and 400° C. The air is then cooled in a storage means and medium pressure direct contact heat recovery (201) until an outlet temperature (17) between 100°C and 50°C is reached. The exchanged heat is stored directly in the heat storage and recovery means (201). The air can then be sent to additional cooling means (301) to reach an outlet temperature (18) of less than or equal to 50°C. Part of the humidity in the air condenses during cooling under pressure. The condensed water (19) can then be separated from the air stream (20) in a gas-liquid separator (401) operating at the pressure and temperature of the inlet stream (18) and sent to a storage tank ( 501). The air separated from the condensed water (20) is compressed via a third high pressure compressor (102) until it reaches a temperature at the compression outlet (21) between 200°C and 400°C. The air is then cooled in a high pressure direct contact heat storage and recovery means (202) until it reaches an outlet temperature (22) between 100° C. and 50° C., preferably between 80° C. C and 50°C. The exchanged heat is stored directly in the heat storage and recovery means (202). The air can then be sent to an additional cooling means (302) to reach an outlet temperature (23) less than or equal to the air storage temperature. Part of the humidity in the air condenses during cooling under pressure. The condensed water (24) can then be separated from the air stream (25) in a gas-liquid separator (402) operating at the pressure and temperature of the inlet stream (23) and sent to a storage tank ( 502). The compressed air flow (25) is sent to the compressed air storage means (1000).

Electricity generation phase

The compressed air (26) is extracted from the compressed air storage means (1000) and can be mixed via a system (600) with a flow of condensed water (27) coming from the high pressure storage (502). The flow rate (27) is optimized so that it is constant throughout the electricity production phase. The compressed air stream (26), optionally mixed with the condensed water stream (27), is sent to the high pressure direct contact heat storage and recovery means (202) so as to be heated between 200°C and 400°C. The condensed water (27) is vaporized in the heat storage and recovery means (202). The hot air flow (29) is expanded in the high pressure turbine (700) which will produce electricity via an alternator. At the turbine outlet, the air pressure has decreased as well as its temperature. The compressed air (30) can then be mixed via a system (601) with a flow of condensed water (31) coming from the medium pressure storage (501). The flow rate (31) is optimized so that it is constant throughout the electricity production phase. The flow of compressed air, optionally mixed with condensed water (32) is sent to the medium pressure direct contact heat storage and recovery means (201) so as to be heated between 200° C. and 400° C. vs. The condensed water (31) is completely vaporized in the heat storage and recovery means (201). The hot air flow (33) is expanded in the medium pressure turbine (701) which will produce electricity via an alternator. At the turbine outlet, the air pressure has further decreased as well as its temperature. The compressed air (34) can be mixed via a system (602) with a flow of condensed water (35) coming from the low pressure storage (500). The flow rate (35) is optimized so that it is constant throughout the electricity production phase. The mixed air or air and condensed water flow (36) is sent to the low pressure direct contact heat storage and recovery means (200) so as to be heated between 200°C and 400°C. The condensed water (35) is completely vaporized in the heat storage and recovery means (200). The hot air flow (37) is expanded in the low pressure turbine (702) which will produce electricity via an alternator.

At the turbine outlet, the air flow (38), at atmospheric pressure and at a temperature between 30° C. and 100° C., is released into the atmosphere. FIG. 3 illustrates, schematically and in a nonlimiting manner, a system and a method for storing and recovering energy by compressed gas (in this case air) according to a particular embodiment of the invention. The flows and steps are detailed below respectively for the electricity storage phase and for the electricity production phase, in the case where the gas is humid air.

Electricity storage phase

The moist air at atmospheric pressure from the external environment (10) is compressed via a first low pressure compression means (100) until it reaches a flow temperature at the compression outlet (11) between 200°C and 400°C , preferably between 250°C and 350°C. The air is then cooled in a low pressure direct contact heat storage and recovery means (200) until it reaches an outlet temperature (12) between 100° C. and 50° C., preferably between 80° C. C and 50°C. The exchanged heat is stored directly in the heat storage and recovery means (200). The air is then sent to additional cooling means (300) to reach an outlet temperature (13) of less than or equal to 50°C. Part of the humidity in the air condenses during cooling under pressure. The condensed water (14) is then separated from the air stream (15) in a gas-liquid separator (400) operating at the pressure and temperature of the inlet stream (13) and sent to a storage tank (500 ). The air separated from the condensed water (15) is compressed via a second medium-pressure compressor (101) until it reaches a temperature at the compression outlet (16) between 200° C. and 400° C., preferably between 250° C. C and 350°C. The air is then cooled in a medium pressure direct contact heat storage and recovery means (201) until it reaches an outlet temperature (17) between 100° C. and 50° C., preferably between 80° C. C and 50°C. The exchanged heat is stored directly in the heat storage and recovery means (201). The air is then sent to additional cooling means (301) to reach an outlet temperature (18) of less than or equal to 50°C. Part of the humidity in the air condenses during cooling under pressure. The condensed water (19) is then separated from the air stream (20) in a gas-liquid separator (401) operating at the pressure and temperature of the inlet stream (18) and sent to a storage tank (501 ). The air separated from the condensed water (20) is compressed via a third high pressure compressor (102) until it reaches a temperature at the compression outlet (21) between 200° C. and 400° C., preferably between 250° C. C and 350°C. The air is then cooled in a high pressure direct contact heat storage and recovery means (202) until it reaches an outlet temperature (22) between 100° C. and 50° C., preferably between 80° C. C and 50°C. The exchanged heat is stored directly in the heat storage and recovery means (202). The air is then sent to an additional cooling means (302) to reach an outlet temperature (23) lower than or equal to the air storage temperature. A part of the moisture in the air condenses when cooling under pressure. The condensed water (24) is then separated from the air stream (25) in a gas-liquid separator (402) operating at the pressure and temperature of the inlet stream (23) and sent to a storage tank (502 ). The compressed air flow (25) is sent to the compressed air storage means (1000).

Electricity generation phase

The compressed air (26) is extracted from the compressed air storage means (1000) and is mixed via a system (600) with a flow of condensed water (27) coming from the high pressure liquid storage (502). The flow rate (27) is optimized so that it is constant throughout the electricity production phase. The mixed air and condensed water stream (28) is heated in the heat exchanger (800) by the Organic Rankine Cycle working fluid (11'). The reheated stream (29) is sent to the high pressure direct contact heat storage and recovery means (202) so as to be reheated between 200°C and 400°C, preferably between 250°C and 350°C. . The condensed water (27) is totally vaporized in the exchanger (800) and/or in the heat storage and recovery means (202). The hot air flow (30) is expanded in the high pressure turbine (700) which will produce electricity via an alternator. At the turbine outlet, the air pressure has decreased as well as its temperature. The compressed air (31) is then mixed via a system (601) with a flow of condensed water (32) coming from the medium pressure storage (501). The flow rate of the flux (32) is optimized so that it is constant throughout the electricity production phase. The mixed air and condensed water stream (33) is sent to the medium pressure direct contact heat storage and recovery means (201) so as to be heated between 200°C and 400°C, preferably between 250°C and 350°C. The condensed water (32) is completely vaporized in the heat storage and recovery means (201). The hot air flow (34) is expanded in the medium pressure turbine (701) which will produce electricity via an alternator. At the turbine outlet, the air pressure has further decreased as well as its temperature. The compressed air (35) is mixed via a system (602) with a flow of condensed water (36) coming from the low pressure storage (500). The flow rate of the flux (36) is optimized so that it is constant throughout the electricity production phase. The mixed air and condensed water flow (37) is sent to the low pressure direct contact heat storage and recovery means (200) so as to be heated between 200°C and 400°C, preferably between 250°C and 350°C. The condensed water (36) is completely vaporized in the heat storage and recovery means (200). The hot air flow (38) is expanded in the low pressure turbine (702) which will produce electricity via an alternator. At the turbine outlet, the air flow (39), at atmospheric pressure and at a temperature between 30°C and 100°C, is sent to the heat exchanger (801) in order to vaporize the flow of working fluid (13') of the Rankine cycle. Once vaporized, the flow of working fluid (10') is sent to the expansion turbine (703) which will produce additional electricity to that produced by the expansion stages, via an alternator. At the outlet of the turbine (703), the flow of working fluid (11') has seen its pressure decrease as well as its temperature, but remains in vapor form. The working fluid flow (11') is sent to the heat exchanger (800) in order to be condensed there. Once condensed, the working fluid flow (12') is sent to the pump (900) in order to increase its pressure. The stream (40) is released to the atmosphere.

The integration of a Rankine cycle in which the hot source is the outlet of the low pressure turbine and the cold source is the outlet of the compressed air storage, in the expansion phase of the adiabatic compressed air storage process , makes it possible to recover the waste heat of the process (additional production of 0.48 MW) while increasing the efficiency, which goes from 70.4% to 70.6%.

Figure 4 illustrates the embodiment of the invention in which a second Rankine cycle is provided. The embodiment of FIG. 4 differs from the embodiment of FIG. 3 only by the addition of a second Rankine cycle, which is why only this second Rankine cycle is described. The second Rankine cycle is arranged between the outlets of the heat transfer fluid from the cooling means (300, 301, 302) and the inlets of the heat transfer fluid from the cooling means (300, 301, 302), the hot source being water ( heat transfer fluid) from the cooling means (300, 301, 302) and collected in a water storage means at a pressure between 4 and 100 bar (between 0.4 and 10 MPa), preferably at the pressure of the first compression stage (503) and the cold source being cooling water (49), for example from a river, the network or any other source of cold water. At the outlet of the storage means (503), the flow of water (44), at a temperature between 50°C and 100°C, is sent to the heat exchanger, called evaporator (803) in order to vaporize the flow of working fluid (16') of said second Rankine cycle. Once vaporized, the flow of working fluid (14') is sent to the expansion turbine (704) which will produce additional electricity, via an alternator. At the outlet of the turbine (704), the flow of working fluid (15') has seen its pressure decrease as well as its temperature but remains in vapor form. The flow of working fluid (15') is sent to the heat exchanger, called condenser (802) fed by the cold source in order to be condensed there. Once condensed, the working fluid flow (16') is sent to the pump (901) in order to increase its pressure. The flow (45) of cooled water is sent to a storage means (504), which replenishes the cooling means (300, 301, 302). The stream of water heated (50) between 30° C. and 40° C. leaves the process and can be returned to the external environment. It goes without saying that the invention is not limited solely to the embodiments of the system and of the method described above by way of example, on the contrary it encompasses all the variant embodiments. In particular, for the embodiments of FIGS. 3 and 4, the steps of water/liquid separation, liquid storage, liquid injection, additional cooling are optional steps. In addition, in these figures, the compression and expansion lines each comprise three stages. However, other embodiments can be envisaged, for example two stages in each line.

Examples

The characteristics and advantages of the method according to the invention will appear more clearly on reading the application examples below.

Example 1 (according to the invention):

This example implements the system and the method according to the embodiment of the invention with reinjection of water illustrated in FIG. 3, in the embodiment in which the water condensed in the compression phase is stored, then reinjected into the flow of compressed air leaving the compressed air storage means (1000) before the expansion phase (FIG. 3 with the dotted elements).

During the compression phase (1), an external air flow (10), at a pressure of 1.02 bar (0.102 MPa) and a temperature of 27° C. and having a humidity of 14.6 g _e au/ kg air _, is compressed by a low pressure compressor (100) from which it leaves (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 heat storage and recovery means (200) which cools the air to a temperature of 80° C. (12) and stores this thermal energy until the cooling phase. relaxation (2). The stream (12) is cooled again by the cooling means (300) until it reaches a temperature of 50° C. at the outlet (13). The flow (13) is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in (200) and/or (300). This condensed water (14) is separated from the process air stream (15) in a gas-liquid separator (400), operating at the pressure of the stream (13), then sent to a storage (500) under a maintained pressure of 6 bar (0.6 MPa). The flow (15), 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 (2.8 MPa). The stream (16) is sent to a medium pressure heat storage and recovery means (201) which cools the air to a temperature of 82°C (17) and stores this thermal energy until the relaxation (2). The stream (17) is cooled again by the 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 phase of cooling in (201). This condensed water (19) is separated from the process air stream (20) in a gas-liquid separator (401), operating at the pressure of the stream (18), then sent to a storage (501) under a maintained pressure of 28 bar (2.8 MPa). The flow (20), again completely gaseous, is compressed by a high pressure compressor (102) from which it emerges (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 means (202) which cools the air to a temperature of 80°C (22) and stores this thermal energy until the cooling phase. relaxation (2). The stream (22) is cooled again by the cooling means (302) until it reaches a temperature of 30° C. at the outlet (23), 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 (202) and/or (302). This condensed water (24) is separated from the process air stream (25) in a gas-liquid separator (402), operating at the pressure of the stream (23), then sent to a storage (502) under a maintained pressure of 117 bar (11.7 MPa).

The flow of compressed air at a pressure of 117 bar (11.7 MPa) and a temperature of 30° C. (25) is then sent to the compressed air storage means (1000) while awaiting the destocking phase. (2).

When it is desired to produce electricity, a flow of condensed water (27) coming from the storage (502) at a pressure of 117 bar (11.7 MPa) 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) to form the flow (28). The stream (28) is preheated in a heat exchanger (800) in order to reach a temperature of 35°C at the outlet (29). The stream (29) is then reheated in the high pressure thermal energy storage (202) which releases the heat stored during the compression phase until the stream (30) reaches a temperature of 240°C. This flow of hot and compressed air (30) is expanded in the high pressure turbine (700) producing electricity via an alternator, until it reaches at the outlet

(31) a pressure of 28 bar (2.8 MPa) and a temperature of 85°C. A flow of condensed water

(32) from the storage (501) at a pressure of 28 bar (2.8 MPa) and a temperature of 50°C is reinjected into the compressed air flow (31) via the mixer (601) to form the flow

(33). The stream (33) is heated in the medium pressure thermal energy storage (201) which releases the heat stored during the compression phase until the stream (34) reaches a temperature of 255°C. This flow of hot, compressed air (34) is expanded in the medium-pressure turbine (701) producing electricity via an alternator, until it reaches a pressure of 5 bar (0.5 MPa) at the outlet (35). and a temperature of 70°C. A flow of condensed water (36) coming from the storage (500) at a pressure of 6 bar (0.6 MPa) and a temperature of 50° C. is reinjected into the flow of compressed air (35) via the mixer ( 602) to form the stream (37). The stream (37) is heated in the thermal energy storage low pressure (200) which releases the heat stored during the compression phase until the flow (38) reaches a temperature of 245°C. This flow of hot, compressed air (38) is expanded in the low-pressure turbine (702) producing electricity via an alternator, until it reaches a pressure of 1.02 bar (0.102 MPa) at the outlet (39). and a temperature of 80°C. This flow (39) is then sent to the heat exchanger (801) allowing the evaporation of the working fluid of said Rankine cycle, here, propane (13'). Once the stream (10') is completely gaseous at a pressure of 28 bar (2.8 MPa) and a temperature of 75°C, it is sent to the expansion turbine (703) producing electricity via a alternator, until a pressure of 13 bar (1.3 MPa) is reached at the outlet (11'). This stream (11') is completely condensed in the heat exchanger (800) used as a condenser until the temperature of 35°C is reached at the stream (12'). This stream (12') is then sent to the pump (900) in order to increase its pressure and to reach 28 bar (2.8 MPa) at the stream (13').

As described above, the efficiency of the energy storage process is 70.6% (compared to 69.6% for conventional AA-CAES without water reinjection and without ORC and compared to 70 .3% for an AA-CAES with water reinjection, but without ORC, as described in FIG. 2 not in accordance with the invention) for a power consumption of 100.0 MW at the compressors. The total flow of condensed water at the three compression stages is 7.5 t/h. The thermal storage power is 87.2 MWth and the cooling power required is 20.3 MWth. The Rankine cycle produces an additional 0.48 MW of electricity compared to a conventional ACAES process as described in Figure 2 (AA-CAES process with expansion water reinjection, but without ORC).

Example 2 (according to the invention):

Example 2 implements the system and the method according to the embodiment of the invention without reinjection of water illustrated in FIG. 3 (FIG. 3, without the dotted elements). In this example, the water condensed and separated from the air after cooling in the compression phase is not reinjected in the expansion phase, but is definitively extracted from the process.

During the compression phase (1), an external air flow (10), at a pressure of 1.02 bar (0.102 MPa) and a temperature of 27° C. and having a humidity of 14.6 g _e au/ kg 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 (0.6 MPa). This flow (11) is sent to a low-pressure heat storage and recovery means (200) which cools the air to a temperature of 90° C. (12) and stores this thermal energy until the cooling phase. relaxation (2). The stream (12) is cooled again by the cooling means (300) until it reaches a temperature of 50° C. at the outlet (13). The flow (13) is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in (200) and/or (300). This condensed water (14) is separated from the process air flow (15) in a gas-liquid separator (400), operating at the pressure of the flow (13), then definitively extracted from the process. The flow (15), 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 (2.8 MPa). The stream (16) is sent to a medium pressure heat storage and recovery means (201) which cools the air to a temperature of 100°C (17) and stores this thermal energy until the relaxation (2). The stream (17) is cooled again by the 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 (201) and/or (301). This condensed water (19) is separated from the process air stream (20) in a gas-liquid separator (401), operating at the pressure of the stream (18), then definitively extracted from the process. The flow (20), again completely gaseous, is compressed by a high pressure compressor (102) from which it emerges (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 means (202) which cools the air to a temperature of 46°C (22) and stores this thermal energy until the cooling phase. relaxation (2). The stream (22) is cooled again by the cooling means (302) until it reaches a temperature of 30° C. at the outlet (23), 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 (202) and/or (302). This condensed water (24) is separated from the process air flow (25) in a gas-liquid separator (402), operating at the pressure of the flow (23), then definitively extracted from the process.

The flow of compressed air at a pressure of 117 bar (11.7 MPa) and a temperature of 30° C. (25) is then sent to the compressed air storage means (1000) while awaiting the destocking phase ( 2).

When it is desired to produce electricity, the flow of compressed air (26) leaving the compressed air storage means (1000) is preheated in a heat exchanger (800) in order to reach the outlet (29 ) a temperature of 35°C. The stream (29) is then reheated in the high pressure thermal energy storage (202) which releases the heat stored during the compression phase until the stream (30) reaches a temperature of 240°C. This flow of hot, compressed air (30) is expanded in the high pressure turbine (700) producing electricity via an alternator, until it reaches a pressure of 28 bar (2.8 MPa) at the outlet (31). and a temperature of 85°C. The compressed air flow (31) is heated in the medium pressure thermal energy storage (201) which releases the heat stored during the compression phase until the flow (34) reaches a temperature of 266°C . This flow of hot and compressed air (34) is expanded in the medium pressure turbine (701) producing electricity via an alternator, until reaching at the outlet (35) a pressure of 5 bar (0.5 MPa) and a temperature of 75°C. The compressed air stream (35) is heated in the low pressure thermal energy storage (200) which releases the heat stored during the compression phase until the stream (38) reaches a temperature of 245°C . This flow of hot, compressed air (38) is expanded in the low-pressure turbine (702) producing electricity via an alternator, until it reaches a pressure of 1.02 bar (0.102 MPa) at the outlet (39). and a temperature of 82°C. This flow (39) is then sent to the heat exchanger (801) used as an evaporator and allowing the evaporation of the working fluid of said Rankine cycle, here, propane (13'). Once the flow of working fluid (10') is completely gaseous at a pressure of 28 bar (2.8 MPa) and a temperature of 75°C, it is sent to the expansion turbine (703) producing gas. electricity via an alternator, until a pressure of 13 bar (1.3 MPa) is reached at the outlet (11'). This stream (11') is completely condensed in the heat exchanger (800) used as a condenser until the temperature of 35°C is reached at the stream (12'). This stream (12') is then sent to the pump (900) in order to increase its pressure and to reach 28 bar (2.8 MPa) at the stream (13').

As described above, the efficiency of the energy storage process is 70.0% (compared to 69.6% for conventional AA-CAES without water reinjection as depicted in Figure 2) for a power consumption of 100.0 MW at the compressors. The total flow of condensed water at the three compression stages is 7.5 t/h. The thermal storage power is 87.0 MWth and the cooling power required is 20.5 MWth. The Rankine cycle produces an additional 0.44 MW of electricity compared to a conventional AACAES process without ORC.

Example 3 (according to the invention):

This example illustrates the embodiment of the system and method according to the invention in which a second Rankine cycle is implemented between the coolant fluid inlets and outlets of the compression line cooling means (Figure 4).

During the compression phase (1), an external air flow (10), at a pressure of 1.02 bar (0.102 MPa) and a temperature of 27° C. and having a humidity of 14.6 g _e au/ kg air _, is compressed by a low pressure compressor (100) from which it leaves (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 heat storage and recovery means (200) which cools the air to a temperature of 80°C (12) and stores this thermal energy until the relaxation (2). The stream (12) is cooled again by the water cooling means (300) until it reaches a temperature of 50° C. at the outlet (13). The cold water flow (46) from the storage (504) is then reheated in said cooling means (300) to form the flow (41) which is stored in the hot water storage (503). The flow (13) is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in (200) and/or (300). This condensed water (14) is separated from the process air stream (15) in a gas-liquid separator (400), operating at the pressure of the stream (13), then sent to a storage (500) under a maintained pressure of 6 bar (0.6 MPa). The flow (15), 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 (2.8 MPa). The stream (16) is sent to a medium pressure heat storage and recovery means (201) which cools the air to a temperature of 82°C (17) and stores this thermal energy until the relaxation (2). The stream (17) is cooled again by the water cooling means (301) until it reaches a temperature of 50° C. at the outlet (18). The cold water flow (47) from the storage (504) is then reheated in the cooling means (301) to form the flow (42) which is stored in the hot water storage (503). The flow (18) is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in (201) and/or (301). This condensed water (19) is separated from the process air stream (20) in a gas-liquid separator (401), operating at the pressure of the stream (18), then sent to a storage (501) under a maintained pressure of 28 bar (2.8 MPa). The flow (20), again completely gaseous, is compressed by a high pressure compressor (102) from which it emerges (21) at a temperature of 250° C. and a pressure of 117 bar (11.7 MPa). The flow (21) is sent to a means of storage and high pressure heat recovery (202) which cools the air to a temperature of 45°C (22) and stores this thermal energy until the phase of relaxation (2). The stream (22) is cooled again by the water exchanger (302) until it reaches a temperature of 30° C. at the outlet (23), 30° C. being the air storage temperature. The cold water flow (48) from the storage (504) is then reheated in the water cooling means (302) to form the flow (43) which is stored in the hot water storage (503). The flow (23) is then composed of air and water, resulting from the humidity of the air, condensed during the cooling phases in (202) and/or (302). This condensed water (24) is separated from the process air stream (25) in a gas-liquid separator (402), operating at the pressure of the stream (23), then sent to a storage (502) under a maintained pressure of 117 bar (11.7 MPa).

The flow of compressed air at a pressure of 117 bar (11.7 MPa) and a temperature of 30° C. (25) is then sent to the compressed air storage means (1000) while awaiting the destocking phase ( 2).

When it is desired to produce electricity, a stream of condensed water (27) coming from the storage (502) at a pressure of 117 bar (11.7 MPa) and a temperature of 30° C. is reinjected into the stream. of compressed air (26) leaving the compressed air storage means (1000) via the mixer (600) to form the flow (28). The stream (28) is preheated in a heat exchanger (800) in order to reach a temperature of 35°C at the outlet (29). The flow (29) is then reheated in the high pressure thermal energy storage (202) which releases the heat stored during the compression phase until the stream (30) reaches a temperature of 240°C. This flow of hot and compressed air (30) is expanded in the high pressure turbine (700) producing electricity via an alternator, until it reaches at the outlet

(31) a pressure of 28 bar (2.8 MPa) and a temperature of 85°C. A flow of condensed water

(32) from the storage (501) at a pressure of 28 bar (2.8 MPa) and a temperature of 50°C is reinjected into the compressed air flow (31) via the mixer (601) to form the flow

(33). The stream (33) is heated in the medium pressure thermal energy storage (201) which releases the heat stored during the compression phase until the stream (34) reaches a temperature of 255°C. This flow of hot, compressed air (34) is expanded in the medium-pressure turbine (701) producing electricity via an alternator, until it reaches a pressure of 5 bar (0.5 MPa) at the outlet (35). and a temperature of 70°C. A flow of condensed water (36) coming from the storage (500) at a pressure of 6 bar (0.6 MPa) and a temperature of 50° C. is reinjected into the flow of compressed air (35) via the mixer ( 602) to form the stream (37). The stream (37) is heated in the low pressure thermal energy storage (200) which releases the heat stored during the compression phase until the stream (38) reaches a temperature of 245°C. This flow of hot, compressed air (38) is expanded in the low-pressure turbine (702) producing electricity via an alternator, until it reaches a pressure of 1.02 bar (0.102 MPa) at the outlet (39). and a temperature of 80°C. This flow (39) is then sent to the heat exchanger (evaporator) (801) allowing the evaporation of the working fluid of said Rankine cycle 1, here, propane (13'). Once the flow of working fluid (10') is completely gaseous at a pressure of 28 bar (2.8 MPa) and a temperature of 75°C, it is sent to the expansion turbine (703) producing gas. electricity via an alternator, until a pressure of 13 bar (1.3 MPa) is reached at the outlet (11'). This flow (11') is completely condensed in the heat exchanger (800) used as a condenser until it reaches a temperature of 35°C at the outlet (flow (12')). This flow (12') is then sent to the pump (900) in order to increase its pressure and reach 28 bar (2.8 MPa) at flow (13').

A Rankine cycle 2, arranged in parallel with the previous one, involves a working fluid, here, propane (17') which is vaporized via the evaporator (803). This evaporator is supplied with hot water (44) from the storage (503) collecting the water from the cooling means (300, 301, 302). Once cooled, the water (45) is returned to the cold water storage (504). The vaporized propane (14') is sent to the expansion turbine (704) producing electricity via an alternator, until it reaches a pressure of 10 bar (1 MPa) at the outlet (15'). This propane stream (15') is then sent to the condenser (802) fed with water at 20°C. Once condensed, the stream (16') is then sent to the pump (901) in order to increase its pressure and reach 22 bar (2.2 MPa) at the stream (17'). In the embodiment described above, the efficiency of the energy storage process is 72.2% (compared to 69.6% for conventional AA-CAES without water reinjection and without ORC and by compared to 70.3% for an AA-CAES with water reinjection but without ORC) for a power consumption of 100.0 MW at the compressors. The total flow of condensed water at the three compression stages is 7.5 t/h. The thermal storage power is 87.2 MWth and the cooling power required is 20.3 MWth. The Rankine cycle 1 makes it possible to produce 0.48 MW of additional electricity and the Rankine cycle 2 makes it possible to produce 1.23 MW of additional electricity compared to a conventional AACAES process as described in Figure 2 (AA-CAES process with reinjection of water in relaxation, but without ORC).

Thus, examples 1 to 3 show that the implementation of at least one Rankine cycle in the system and the method according to the invention in any one of its variants, makes it possible to increase the performance of the AA- CAES, while limiting the power required for cooling.

Claims

Claims 1. Compressed gas energy storage and recovery system comprising: -A gas compression line (1) with at least one compression stage (3), each compression stage (3) comprising compression means (100, 101, 102) and means for storing and recovering the heat (200, 201, 202) arranged downstream of said compression means (100, 101, 102), in the direction of circulation of said gas, -At least one compressed gas storage means (1000) arranged at the outlet of said gas compression line (1) to store said compressed gas, -A gas expansion line (2) for expanding said compressed gas stored in said compressed gas storage means (1000), said gas expansion line (2) comprising at least one expansion stage (4), each stage expansion (4) comprising expansion means (700, 701, 702) and pipes configured to circulate said compressed gas in at least one of said heat storage and recovery means (200, 201, 202) of said stages compression (3) so as to heat said compressed gas, - At least one Rankine cycle comprising an expansion turbine (703), a condenser (800), a pump (900) and an evaporator (801), and pipes configured to circulate a working fluid adapting to the temperatures involved in said Rankine cycle, to produce an additional quantity of energy on expansion, and arranged between said compressed gas storage means (1000) whose output stream (26), optionally mixed with a liquid, constitutes the cold source and said expansion means (702) whose outlet flow (39) constitutes the hot source in the direction of circulation of said gas. 2. System according to claim 1 wherein each expansion stage (4) comprises means for introducing a liquid (600, 601, 602), said means for introducing said liquid (600, 601, 602) being provided upstream, in the direction of circulation of said gas, of said heat storage means (200, 201, 202) and said Rankine cycle being arranged between said means for introducing said liquid (600) whose outlet flow (28 ) constitutes the cold source and said expansion means (702) whose outlet flow (39) constitutes the hot source in the direction of circulation of said gas. 3. System according to claim 1 or 2, wherein said heat storage and recovery means (200, 201, 202) comprise heat storage particles. 4. System according to one of the preceding claims wherein each compression stage (3) comprises means for separating said gas and a liquid (400, 401, 402). 5. System according to claim 4, in which, for each compression stage, said means for separating gas and liquid (400, 401, 402) is arranged downstream of said means for storing and recovering heat (200, 201, 202), in the direction of flow of said gas. 6. System according to one of claims 4 or 5, wherein said system comprises a plurality of liquid storage means (500, 501, 502) for storing said liquid at the outlet of said gas and liquid separation means (400 , 401, 402), and said introducing means (600, 601, 602) introduces said liquid from said liquid storage means (500, 501, 502). 7. System according to one of the preceding claims, wherein said compression line (1) comprises as many compression stages (3) as the expansion line (2) comprises expansion stages (4), each means storage and heat recovery (200, 201, 202) of a compression stage (3) being used in the corresponding expansion stage (4). 8. System according to claim 7, wherein said compression line (1) and said expansion line (2) respectively comprise three stages. 9. System according to one of the preceding claims, wherein at least one compression stage (3) comprises cooling means (300, 301, 302) downstream of the heat storage and recovery means (200, 201 , 202), in the direction of circulation of said gas, preferably, said cooling means (300, 301, 302) comprises an air cooler or heat exchangers exchanging with a coolant. 10. System according to claim 9 comprising a second Rankine cycle comprising an expansion turbine (704), a condenser (802), a pump (901) and an evaporator (803), and conduits configured to circulate a fluid of work adapting to the temperatures involved in said second Rankine cycle, said second Rankine cycle being arranged between two liquid storage means (503) and (504), said liquid storage means (503) collecting the flows of heat transfer fluid outlet from said cooling means and said liquid storage means (504) distributing the heat transfer fluid inflows from said cooling means, the hot source of said second Rankine cycle being the heat transfer fluid from said cooling means (300 , 301, 302) stored in the liquid storage means (503) and the cold source of said second cycle being an external flow of cooling liquid, preferably water (49). 11. System according to one of the preceding claims, in which the working fluid of said Rankine cycle(s) is chosen from propane, butane or any other refrigerant fluid adapting to the temperatures involved in said Rankine cycle. Rankine. 12. Compressed gas energy storage and recovery process comprising at least the following steps: - In the energy storage phase: a) a gas is successively compressed at least once in a compression line (1) comprising at least one compression stage (3), each compression stage (3) comprising at least one compression means (100, 101, 102); b) after each compression step, the heat of said compressed gas is recovered in at least one heat storage and recovery means (200, 201, 202); c) said cooled compressed gas is stored in at least one compressed gas storage means (1000); - In the energy recovery phase: d) the compressed gas leaving the compressed gas storage means (1000) is circulated in an expansion line (2) comprising at least one expansion stage (4), and in each expansion stage (4), the compressed gas is heated by circulating it in one of said heat storage and recovery means (200, 201, 202) using the heat stored during the compression stage and then expanded the compressed gas heated in an expansion means (700, 701, 702); e) an additional quantity of energy is produced on expansion, by means of at least one Rankine cycle comprising an expansion turbine (703), a condenser (800), a pump (900) and an evaporator (801) , the flow of gas leaving the low pressure turbine (702) being used as a heat source within the evaporator (801) to evaporate the working fluid of said Rankine cycle before its expansion in the expansion turbine (703) and the stream composed of compressed gas leaving the compressed gas storage means (1000) or the stream consisting of compressed gas and liquid coming from the mixer (600) being used as a cold source within the condenser (800) to condense the fluid work of said Rankine cycle before its compression in the pump (900). 13. Method according to claim 12, in which the heat is stored in heat storage particles, 14. The method of claim 12 or 13 wherein after each compression step, separating said gas and a liquid present in said gas. 15. The method of claim 14, wherein said separated liquid is stored, and said liquid introduced into said compressed gas is said stored liquid. 16. Method according to one of claims 12 to 15, in which as many compression steps as expansion steps are carried out, and the heat storage and recovery means (200, 201, 202) are used. of each of steps b) to heat the compressed gas of the corresponding expansion step. 17. Method according to one of claims 12 to 16, wherein after each heat recovery step, the compressed gas is cooled at the outlet of the heat storage and recovery means (200, 201, 202) in a cooling means (300, 301, 302) before the gas is sent to the next compression stage or to the compressed gas storage means (1000). 18. Process according to claim 17, in which an additional quantity of energy is produced upon expansion by means of a second Rankine cycle comprising a turbine of expansion (704), a condenser (802), a pump (901) and an evaporator (803), arranged between a liquid storage means (503) allowing the hot heat transfer fluid to be collected at the outlet of said cooling means (300, 301 , 302) and a liquid storage means (504) for supplying cold heat transfer fluid to said cooling means (300, 301, 302), the flow of hot heat transfer fluid from said cooling means (300, 301, 302) being used as a heat source within the evaporator (803) to evaporate the working fluid of said Rankine cycle before its expansion in the expansion turbine (704); an external flow of cooling liquid (49), preferably water, being used as a cold source within the condenser (802) to condense the working fluid of said second Rankine cycle before its compression in the pump (901) ; and the cooled coolant flow exiting the evaporator (803) being stored in said liquid storage means (504).