FR3103542A1 - Radial thermal storage device by sorption of a fluid on an adsorbent material - Google Patents

Abstract

The present invention relates to a heat storage device and method comprising at least one bed (14) of adsorbent material (9) separating an external volume (10) and a central volume (15). In this way, a fluid can pass transversely from one volume to the other by crossing the bed (14) of adsorbent material (9). As it passes through the bed, an adsorption/desorption phenomenon takes place, allowing heat to be generated or stored. The beds (14) are separated by trays (11, 12) integral with an outer casing (13) and these trays (11, 12) are fluid tight. Figure 2 to be published

Description

Radial thermal storage device by sorption of a fluid on an adsorbent material

The present invention relates to the field of heat storage, and more particularly to thermal storage units by sorption of a fluid on an adsorbent material such as zeolite.

Sorption thermal storage devices on an adsorbent material by direct contact operate on the principle of material and heat exchanges between a gas and an adsorbent material in adsorption columns. These columns generally operate in gas flow alone, in a fixed bed of adsorbent material.

The columns used in these heat storage units operate by the principles of adsorption on the adsorbent material of a molecule present in the gaseous phase, for example water (H ₂ O) in vapor form in air , and heat exchange between the solid phase (zeolite for example) and the gaseous phase, air for example. The gaseous phase acts as a heat transfer fluid.

Heat storage units mainly operate in four stages or periods:

- The first period, known as the "discharge period", consists in generating heat by bringing the heat transfer fluid into direct contact, for example air laden with humidity, in an adsorption column equipped with a fixed bed of adsorbent material , for example zeolite. The adsorption of humidity in the adsorbent material generates heat (exothermic phenomenon). This heat is transferred to the heat transfer fluid and then transported to the area of use. The terminology used "discharge period" relates to the heat discharge by the zeolite. It corresponds to a phase during which heat is generated.

- The second period called “first break period”. This phase corresponds to the waiting period between the discharge phase and the charging phase described below.

- The third period, called the "load period", consists of using waste heat, waste heat being defined as a production of heat derived from a production site, which is not its primary purpose, and which, fact, is usually not used (in other words, the waste heat constitutes energy available to be stored), to regenerate the bed of adsorbent material before it is used for another period of discharge. In this phase, the molecules, previously adsorbed during the discharge phase, are desorbed by the regeneration fluid. For example, water molecules are desorbed from the adsorbent material in the dry air used as the regeneration fluid.

- The fourth period, called the “second pause period” or “storage period” corresponds to a thermal energy storage time.

The discharge, pause, charge and storage periods can be spread over several minutes, several hours, even several days or several months in the case of seasonal storage.

Figure 1 shows a conventional sorption thermal storage device consisting of a column equipped with a fixed bed of adsorbent material (1), a bed support grid (2) and a jet diffuser (3) . Such a device is for example described in M. Gaeini, H.A. Zondag, C.C.M. Rindt. Effect of kinetics on the thermal performance of a sorption heat storage reactor. Applied Thermal Engineering, 102 (2016). 520–531. For very tall columns, the bed of adsorbent material can be composed of several bed sections supported by several grids.

The heat transfer gas can be introduced from the top or the bottom of the column. For example, during the discharge period (D), gas, for example moist air, can be introduced through an inlet (E/S) from the bottom of the column (5) at a temperature between 15 to 100 degrees Celsius and exits through an outlet (S/E) at the top of column (4) at a temperature between 30 and 220 degrees Celsius (see Figure 1) depending on the water vapor concentration of the gas introduced. During the charge or regeneration period (R), the regeneration fluid, for example dry air, is introduced through an inlet (S/E) at the top of the column (4) at a temperature of approximately 220 degrees Celsius and exits the column through an output (I/O) at the bottom (5). Charge, regeneration, and pause cycle times vary by process. They can be several minutes, several hours or several days, even several months.

An embodiment of a mobile sorption thermal storage device is presented in patent application DE102013106039A1. The invention describes a sorption thermal storage device installed on a utility transport trailer (a truck). The mobile thermal storage device composed of a cylindrical container equipped with a cone in the center. The bed of adsorbent material is loaded into an annular area between the wall of the central cone and the annular space located between the wall of the cylindrical container and the bed of adsorbent material. The flow of the heat transfer fluid takes place radially in the bed.

In order to improve the performance of the prior art, the invention relates to a thermal storage device by sorption of a fluid on an adsorbent material, the device comprising a casing, preferably cylindrical. The device also comprises at least one external volume (preferably an annular volume) and at least one central volume, the external and central volumes being included in the envelope and being separated by at least one bed of adsorbent material. Furthermore, at least one first fluid inlet/outlet means is connected to the central volume and at least one second fluid inlet/outlet means is connected to the outer volume. Each bed of adsorbent material is delimited by a lower plate and by an upper plate. In addition, the lower and upper plates are integral with the casing and they are fluid tight.

The invention relates to a thermal storage device by sorption of a fluid on an adsorbent material, the device comprising an envelope, at least one external volume and at least one central volume, the said external and central volumes being included in the said envelope and being separated by at least one bed of said adsorbent material, at least one first inlet/outlet means of said fluid being connected to said at least one central volume, at least one second inlet/outlet means of said fluid being connected to said at least one volume external, each bed of adsorbent material being delimited by a lower plate and by an upper plate. In addition, said lower and upper plates are integral with said casing and said lower and upper plates are sealed to said fluid.

Preferably, the adsorbent material comprises at least one zeolite.

According to one configuration of the invention, said envelope is a cylindrical envelope and said external volume is an annular volume.

According to one embodiment of the invention, the bed of adsorbent material comprises on its internal periphery and/or on its external periphery a means for distributing the fluid.

Preferably, the fluid distribution means comprises a porous wall or a wall comprising regularly distributed holes or orifices.

Advantageously, dispersion means are positioned in the external volume and/or in the central volume.

According to an advantageous implementation of the invention, the device comprises several beds of adsorbent material, said central volumes of said beds of adsorbent material being interconnected.

Advantageously, each of the second fluid inlet/outlet means comprises a solenoid valve, said second fluid inlet/outlet means being connected to a common fluid supply.

According to a preferred variant of the invention, the device comprises several storage stages, each storage stage comprising an external volume, a central volume and a bed of adsorbent material separating the external volume and the central volume, preferably, the stages of storage being stacked.

The invention also relates to a process for storing heat by sorption of a fluid on an adsorbent material, in which the following steps are carried out:

- in the discharge phase:

* the moisture-laden fluid is brought into one of the external or central volumes of said storage device according to one of the preceding characteristics by one of the input/output means,

* the fluid is passed transversely, preferably radially, into the bed of adsorbent material, on which said fluid is adsorbed, releasing its humidity and releasing heat transmitted to the fluid, advantageously at a temperature between 50 and 300° C, preferably between 50 and 250°C, very preferably between 90 and 220°C,

* said hot, dry fluid is brought out of the bed of adsorbent material by the other of said outer or central volumes of said storage device;

* Said hot, dry fluid is brought out of said storage device by the other of said input/output means.

The invention also relates to a process for storing heat by sorption of a fluid on an adsorbent material, in which the following steps are carried out:

- in charging or regeneration phase:

* the fluid, preferably hot and dry, is brought into one of the external or central volumes of said storage device according to one of the preceding characteristics by one of the input/output means,

* the fluid is passed transversely, preferably radially, in the bed of adsorbent material in which the fluid desorbs the moisture adsorbed during the discharge phase by storing the heat,

* said wet fluid is brought out of the bed of adsorbent material by the other of said external or central volumes of said storage device,

* Said wet fluid is brought out of said storage device by the other of said input/output means.

Advantageously, the invention relates to a process for storing heat by sorption of a fluid on an adsorbent material, in which the steps of the discharge phase described above are carried out and in which the steps of the charge phase described above are carried out. .

Preferably, the fluid is distributed through the bed of adsorbent material.

According to one implementation of the method according to the invention, the fluid is dispersed in the external volume and/or in the central volume.

Preferably, the fluid is introduced into the various beds of adsorbent materials.

According to a preferred implementation of the invention, the fluid is air and the molecules are water molecules.

List of Figures

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

FIG. 1 represents a cross-sectional view along the vertical axis (according to the operating position) of a sorption device in an implementation according to the prior art.

FIG. 2 represents a cross-sectional view along the vertical axis of a first embodiment of the sorption device according to the invention.

FIG. 3 represents a cross-sectional view along the vertical axis of a second embodiment of the sorption device according to the invention.

The efficiency and performance of thermal storage devices depend on the characteristics of the adsorbent materials) used, but also on the operating conditions and the transport parameters in the bed of adsorbent material such as the transfer of matter and heat between the solid and the heat transfer fluid, the superficial velocity of the heat transfer fluid, the water vapor concentration, the pressure drops in the bed, among others.

To achieve optimum efficiency of the thermal storage device, the design of the latter must ensure, on the one hand, the proper use of the storage capacity offered by the adsorbent material and, on the other hand, respect a low pressure drop, acceptable for the process.

For optimum use of the storage capacity of the adsorbent material which makes it possible to ensure maximum efficiency of the storage device, in the discharge phase, it is necessary to use optimum operating conditions. For example, with a fluid which is humid air, in the discharge phase, it is necessary to choose the concentration of humidity in the air carefully. It is also necessary to ensure a suitable superficial velocity of the heat transfer fluid to avoid limitations in heat and material transfer which penalize the efficiency of the device. Optimum efficiency of the thermal storage device results in optimum utilization of the capacity of the adsorbent material to generate the thermal energy. The maximum energy E _theo , resulting from the adsorption for example of water vapor in the zeolite, that the device can provide can be estimated by the following relationship:

m_crazy: total mass of adsorbent material in the thermal storage device

q_soft(kg_soft/kg_mad) : concentration of the adsorbed molecule, for example H₂O, at Temperature, Operating pressure (isothermal)

ΔH _ads (J/kg _H2O ): adsorption enthalpy

To characterize the performance of the thermal storage device, the efficiency η of the device is defined as the ratio between the thermal energy at the output of the device E _device and the theoretical energy E _theo defined previously.

In general, it has been observed, surprisingly by the applicant, that the efficiency of the storage device in the discharge phase is markedly better when the contact time is short. The contact time is defined as the ratio of the height or length of the bed of adsorbent material L, defined as the length of the bed in the direction of fluid flow through the bed, to the superficial fluid velocity V _SG , the superficial velocity of the fluid being defined as the ratio between the volume flow and the flowing surface of the bed.

The value of the optimal contact time for a given storage device depends on the operating conditions, but also on the duration of the discharge period.

To improve the efficiency of the system, the invention relates to a thermal storage device by sorption of a fluid on an adsorbent material. The fluid serves as a heat transfer fluid and can be, for example, a gas, such as air. The fluid includes molecules that will be able to adsorb on the adsorbent material and then desorb from the adsorbent material. These molecules can in particular be water molecules, in the form for example of water vapor contained in the fluid, in particular in the air. The adsorbent material can then be a hydrophilic mesoporous material such as silica gel or activated alumina (activated alumina is a very porous aluminum oxide, with a specific surface area greater than 200 m²/g, preferably greater than 300 m²/g), or a microporous material of the zeolite or related type.

By mesoporous, we mean materials whose pore diameters are between 2 and 50 nm. By microporous, we mean materials whose pore diameters are less than 2 nm. The preferred microporous materials in the context of the invention are aluminosilicates such as for example zeolites with structural type LTA, FAU or EMC-2 (with EMT structure), but also aluminophosphates, designated AlPO, such as for example AlPO- 18 of structural type AEI or AlPO-LTA of structural type LTA, silico-aluminophosphates, designated SAPO, such as for example SAPO-34 of structural type CHA, as well as MOFs (Metal Organic Framework) such as UIO-66 , MIL-101, HKUST.

The structural types LTA, FAU, EMT, AEI and CHA correspond to the structural type codes of zeolites defined by the IZA (International Zeolite Association).

During the adsorption of the molecules contained in the fluid on the adsorbent material, heat is generated, the phenomenon of adsorption being an exothermic phenomenon. This heat can then be recovered by using the fluid as a heat transfer fluid for its transport.

During the desorption of the molecules fixed on the adsorbent material in the fluid, the temperature of the fluid is reduced because the desorption is endothermic. The heat from the fluid is therefore stored by the molecules in the fluid, with a view to future adsorption which will allow the heat to be generated at the desired time.

The device includes an envelope, at least one outer volume and at least one central volume. These volumes are placed in the envelope and are separated by at least one bed of adsorbent material. In addition, each bed of adsorbent material is delimited by a lower plate and an upper plate, these plates being integral with the casing and impermeable (by impermeable is meant impermeable) to the fluid. The external volume is thus delimited by the upper and lower plates as well as by the envelope and the external surface of the bed of adsorbent material. The central volume is delimited by the lower and upper plates and by the internal surface of the bed of adsorbent material. Thus, the passage of the fluid through the bed of adsorbent material from one of the two external or central volumes to the other of these volumes is done transversely. By transverse is meant in a direction perpendicular or substantially perpendicular to the main axis of the envelope, this axis being for example vertical. Preferably, the passage of fluid can take place radially.

By the rigid connection of the plates on the envelope, the weight of the bed or beds of adsorbent material is taken up by the envelope, which simplifies the overall design by avoiding having to install systems in the envelope for the recovery of these efforts.

Furthermore, at least one first input/output means is connected to at least one central volume and at least one second input/output means is connected to at least one external volume. Thus, the fluid can be brought in by one of these inlet/outlet means and brought out by the other, the flow of fluid taking place from one of these inlet/outlet means towards the other means of entry/exit.

Preferably, the adsorbent material may comprise zeolite, that is to say at least one zeolite. The use of zeolite allows the production of adsorbent material in different forms, for example, in the form of powder, granules or extrudates. In addition, zeolite is particularly suitable for the adsorption of water molecules. Also, the use of zeolite allows higher heat of adsorption than mesoporous materials like silica gel and zeolite is cheaper than other microporous materials like SAPO or AIPO.

According to a preferred arrangement of the invention, the envelope can be a cylindrical envelope and the external volume can be an annular volume. In addition, the bed of adsorbent material can have an annular shape. The central volume, for example of cylindrical shape, the bed of annular adsorbent material, the annular external volume and the cylindrical envelope are preferably coaxial. Thus, the fluid is evenly distributed in the volumes and in the bed of adsorbent material, avoiding the creation of a privileged fluid flow path which would be detrimental to the performance of the system. In this configuration, the flow of the fluid in the bed of adsorbent material is radial or substantially radial.

Preferably, the axis of the cylindrical envelope is vertical. Thus, the weight of the adsorbent material is taken up by the plates and, due to the presence of a rigid connection between the plates and the envelope, by the envelope.

Advantageously, the bed of adsorbent material may comprise on its internal periphery and/or on its external periphery a fluid distribution means. As a result, the distribution of the fluid in the bed of adsorbent material is improved and thus the performance of the device is increased. In addition, these distribution means can serve as walls allowing the bed to be held in position, in particular when the envelope is positioned substantially vertically. These distribution means are preferably juxtaposed to the bed of adsorbent material, at the junction between the bed and the external or annular volume.

According to the implementation in which the envelope is cylindrical, the external volume is annular and the bed of adsorbent material is annular, the distribution means positioned at the internal and/or external periphery of the bed, can be of annular or cylindrical shape. .

Preferably, the fluid distribution means may comprise a porous wall or a wall comprising regularly distributed holes or orifices. Thus, the distribution means is made easily and the distribution of the fluid in the bed is homogeneous. The use of walls for the distribution means is also suitable for retaining the adsorbent materials of the bed laterally in position and preventing their escape. When the casing and the bed are positioned on the vertical or substantially vertical axis, a thin wall suffices to hold the bed radially in position, which makes it possible to reduce the weight of the assembly, its cost and to gain in efficiency on the device and the associated method.

Advantageously, dispersion means can be positioned in the external volume and/or in the central volume. As a result, the fluid is distributed homogeneously in the external volume and/or in the central volume, which makes it possible to improve the efficiency of the device and of the associated method.

For example, these dispersion means may consist of porous walls or provided with orifices so as to disperse the fluid evenly in the volumes concerned.

According to a variant of the invention, the device can comprise several beds of adsorbent material, separated by fluid-tight plates. Several external and central volumes can then be used. Thus, the device can comprise several storage stages, each storage stage comprising an external volume (for example an annular volume delimited by the preferably cylindrical casing), a central volume, for example cylindrical, and a bed of adsorbent material, the bed of adsorbent material separating the external volume and the central volume of the storage stage.

Therefore, in each storage stage, the passage of the fluid in the bed takes place radially. The device comprises several beds of adsorbent material, several external volumes and several central volumes, the number of beds being identical to the number of external volumes, itself identical to the number of central volumes. The central volumes can be connected together forming a central overall volume. This configuration allows great flexibility since the number of stages can be adapted and the design of each stage can be optimized according to the operating parameters.

It is also possible to choose the adsorbent material according to the temperatures and the concentration rate of the molecules in the fluid, which further improves the efficiency of the system. Thus, each storage stage can include an adsorbent material with a different characteristic (choice of material, particle size, shape, etc.). This configuration therefore allows great flexibility of the device and of the associated method.

According to a particular implementation of the invention, the central volumes of the different beds of adsorbent material can be connected to each other. This simplifies the system, while maintaining system efficiency.

Preferably, the different storage stages can be superposed, in particular superposed vertically. This is particularly advantageous when the axis of the envelope is vertical. The beds of adsorbent materials can then be positioned one above the other, the external volumes can be positioned one above the other and the central volumes can be positioned one above the other. In addition, watertight trays can be put in place to separate the beds and the central volumes or the external volumes. For example, sealed plates can separate a lower bed and an upper bed, the lower bed and the upper bed being in contact with the sealed separation plate. The same plate can also separate the upper outer volume and the inner outer volume, the upper and lower outer volumes being delimited by the separation plate and these volumes being respectively linked to the upper bed and to the lower bed. Thus, the device has several storage stages whose operations are independent of each other. Stacking the floors saves space and therefore reduces the size while limiting the number of interface devices.

Advantageously, each of the second fluid inlet/outlet means connected to each of the external volumes can comprise a valve or a solenoid valve, said second inlet/outlet means being connected to a common fluid supply. Indeed, the valves allow the opening or the closing authorizing or preventing the passage of the fluid in the various external volumes. The control of these openings, in particular by solenoid valves, makes it possible to pass through each of the beds in an optimal time. The control of these solenoid valves can also make it possible to cause the fluid to pass through each bed at optimum temperature conditions, each of the beds being able to be configured to have a different optimum operating temperature. The performance of the device and of the method can thus be increased.

The invention also relates to a process for storing heat by sorption of a fluid on an adsorbent material.

In this process, during the discharge, the following steps can be carried out:

* the fluid laden with molecules to be adsorbed (for example air laden with water vapor) is introduced into one of the external (for example annular) or central volumes of the storage device according to one of the preceding characteristics by a input/output means,

* the fluid is passed transversely, preferably radially, in the bed of adsorbent material, on which the fluid is adsorbed by releasing the molecules to be adsorbed on the adsorbent material (for example, the humidity of the air is adsorbed on the adsorbent material) and by releasing heat transmitted to the fluid, advantageously at a temperature between 50 and 300°C, preferably between 50 and 250°C, very preferably between 90 and 220°C,

* the hot and dry fluid is brought out of the bed of adsorbent material by the other of the external (for example annular) or central volumes of the storage device;

* the hot fluid discharged in molecules to be adsorbed (for example hot and dry air) is brought out of the storage device by the other of the inlet/outlet means.

By passing transversely, preferably radially, in the bed of adsorbent material, the passage time of the fluid in the bed of adsorbent material is reduced compared to the passage time of the fluid in the bed according to the known device of the prior art, as in Figure 1. The reduced passage time makes it possible to avoid an increase in the temperature of the bed of adsorbent material, thus reducing its adsorption capacity, which would correspond to waste heat and therefore to a loss of device performance. On the contrary, by ensuring a reduced residence time, the heat generated by the adsorption is mainly transmitted to the fluid and can then be efficiently recovered. In addition, by ensuring the exit through the central volume, the energy losses through the envelope are further reduced, which improves the performance of the device.

In this process, during charging, the following steps can be carried out:

* the fluid, preferably hot and dry air, is introduced into one of the outer (for example annular) or central volumes of the storage device according to one of the preceding characteristics, by one of the inlet/outlet means of the storage device,

* the fluid is passed transversely, preferably radially, in the bed of adsorbent material in which the fluid desorbs the molecules which are fixed on the adsorbent material during the discharge phase (for example, the humidity adsorbed during the phase discharge). As a result, heat is stored (in the form of sensible heat and sorption enthalpy) and can be reused during the discharge phase when desired. By sensible heat is meant the quantity of heat which is exchanged, without physical phase transition, between several bodies forming an isolated system. It is qualified as “sensitive” because the thermal transfer without phase change changes the temperature of the body, effect. Sensible heat is therefore opposed to "latent heat", which is absorbed during a phase change, without a change in temperature.

* the fluid comprising the molecules desorbed from the bed of adsorbent material is brought out by the other of said external (preferably annular) or central volumes of the storage device,

* the fluid comprising the molecules desorbed from the storage device is brought out by the other of the input/output means.

By passing transversely, preferably radially, in the bed of adsorbent material, the passage time of the fluid in the bed of adsorbent material is reduced compared to the passage time of the fluid in the bed according to the known device of the prior art, as in FIG. 1. The reduced passage time makes it possible to avoid a significant reduction in the temperature of the bed of adsorbent material. In addition, this method makes it possible to use a device as described above in a reversible manner, the same device being able to be used for the discharging phase and for the charging phase. In addition, by ensuring the entry of the hot and dry fluid through the central volume, the energy losses through the envelope are further reduced, which improves the performance of the device.

Advantageously, the invention may relate to a process for storing heat by sorption of a fluid on an adsorbent material in which the steps described above are carried out during the discharge phase and in which the steps described above are carried out during the phase dump. Thus, the advantageous effects obtained during charging and during charging are combined, which further improves the performance of the process.

According to a preferred variant of the method according to the invention, the fluid can be distributed through the bed of adsorbent material, for example by using the distribution means of the device described above. As a result, the fluid is evenly distributed in the bed, which improves performance.

Advantageously, the fluid can be dispersed in the external volume and/or in the central volume. Thus, the fluid is evenly distributed in the external volume and/or in the central volume, which makes it possible to improve the yield of the process. To do this, the dispersion means described above can be used.

According to a preferred embodiment of the invention, the fluid can enter the different beds of adsorbent materials, for example successively or simultaneously. By acting successively (or by staggering the start/stop of passage through each of the beds), each of the beds can be designed optimally for configurations of passage speed, temperature and/or concentration rate of molecules of the fluid. Since the beds are separated from each other by fluid-tight plates, the fluid cannot pass longitudinally (vertically ascending or descending, for example) into an adjacent bed via the plate positioned at the junction. This further optimizes the yield of the process.

By acting simultaneously, the beds can be used in parallel, which allows the stored heat to be recovered much more quickly.

Figure 2 illustrates, schematically and without limitation, a first embodiment of the device according to the invention.

This device comprises a cylindrical casing 13. Inside this cylindrical casing 13, is placed a bed 14 of adsorbent material 9. This bed of adsorbent material is supported by a lower plate 12, including the weight of the bed14 of adsorbent material 9. The cylindrical envelope is placed on the vertical or substantially vertical axis. Above the bed 14 of adsorbent material 9, a plate 11 serves to delimit the bed in its upper part. The lower 12 and upper 11 plates are fluid tight. Thus, they serve as a guide and impose a fluid flow path.

The bed 14 of adsorbent material 9, of annular shape of width L, is also delimited by distribution means 8 positioned on either side of the internal and external peripheries of the bed 14 of adsorbent material 9, the distribution means being juxtaposed to the bed 14. Thus, a first distribution means 8 is positioned on the external cylindrical surface of the bed 14 of adsorbent material 9 and a second distribution means 8 is positioned on the internal cylindrical surface of the bed 14 of adsorbent material 9. These means distribution extend over the entire length, in the axial direction, of the bed 14 of adsorbent material 9 so as to distribute the fluid homogeneously over the entire length of the bed 14 of adsorbent material 9.

The bed 14 of adsorbent material 9 separates a central volume 15, of cylindrical shape, and an outer volume 10 of annular shape. The annular external volume is comprised between the casing 13 and the external distribution means 8 (positioned at the junction between the annular external volume 10 and the bed 14 of adsorbent material 9). It is also delimited by the upper plate 11 and by the lower plate 12, the lower plate 12 comprising a passage means 7 allowing the fluid which arrives in the casing 13 by the inlet/outlet means 6 to reach the volume external volume 10 (or to allow its output from external volume 10). The central volume 15 is delimited by the internal distribution means 8 positioned on the internal surface of the bed 14 of adsorbent material 9. It is also delimited by the lower plate 12 and by the upper plate 11. The upper plate 11 has a passage means of diameter d _i , substantially equal to the internal diameter of the internal distribution means 8 so as to allow the passage of the fluid arriving from the central volume 15 towards the inlet-outlet means 12 (or vice versa). Thus, to move from one of the input/output means 6/12 to the other of the input/output means 12/6, the fluid is forced to pass through one of the external 10 or central 15 volumes. , then through the bed 14 of adsorbent material 9 and finally through the other of the outer 10 or central 15 volumes, the sealed plates thus guiding the fluid. The passage of fluid in the bed 14 of adsorbent material 9 is therefore substantially radial.

The envelope 13, the distribution means 8, the bed 14 of adsorbent material 9 are coaxial, with a vertical or substantially vertical axis. The input/output means 6 and 12 are positioned on the axis of the envelope but could, without departing from the scope of the invention, be positioned elsewhere, for example, positioned off-center or radially.

In FIG. 2, the cylindrical casing 13 comprises two bottoms allowing the junction between the cylindrical part and the inlet/outlet means 6 and 12. These bottoms can be of hemispherical or torispherical shape to improve the resistance to pressure or the resistance under the device's own weight. According to another embodiment not shown, the bottoms could be flat.

Juxtaposed to the inlet/outlet means 6 and 12, are positioned diffusion means 16, such as perforated plates, in order to distribute the fluid in the volumes of the bottoms.

Each of the input/output means 6 and 12 is connected to at least one of the supply or collection pipes E/S and S/E allowing the device to be supplied with fluid or, on the contrary, the fluid coming out of the device to be collected. .

During the discharge phase D represented by the solid black arrows, the fluid arrives via the I/O supply pipe and enters the device via the inlet/outlet means 6. It is then dispersed in the lower bottom of the casing 13 by the dispersion means 16. Passing through the passage means 7 of the lower plate 12, the fluid reaches the annular external volume 10. The sealed upper plate 11 imposes on the fluid a radial passage through the bed 14 of adsorbent material 9 where the molecules that the fluid contains will be adsorbed on the adsorbent material. During this adsorption, the heat generated is transmitted to the fluid which emerges from the bed 14 of adsorbent material 9 hotter than it entered. As the radial length L of the bed is relatively small (compared to the longitudinal length of the prior art according to Figure 1), the heat generated by the adsorption is evacuated quickly by the fluid, without heating (or by heating very little) adsorbent materials). Thus, energy losses are reduced. Thereafter, the fluid reaches the central volume 15 and exits through the inlet/outlet means 12 to reach the collection pipe S/E. The heat recovered by the fluid can then be used.

During the discharge, the fluid could arrive via the inlet/outlet means 12 and come out via the inlet/outlet means 6.

During the charging phase R represented by the gray arrows in dotted lines, the fluid arrives via the supply pipe S/E and enters the device via the inlet/outlet means 12. It is then dispersed in the bottom upper part of the casing 13 by means of dispersion. It enters the central volume 15 of diameter di through an axial orifice in the upper plate 11, the axial orifice being of diameter di equal to the diameter of the central volume 15, so as to avoid unnecessary pressure drops. As a result, system performance is improved. The lower plate 12 imposes on the fluid a radial passage through the bed 14 of adsorbent material 9 where the molecules that the bed contains will be desorbed from the adsorbent material 9 towards the fluid. During this desorption, the heat of the fluid arriving in the device is stored, the desorption being endothermic. The fluid therefore emerges colder from the bed 14 of adsorbent material and emerges loaded with desorbed molecules. As the radial length L of the bed is relatively small (compared to the longitudinal length of the prior art according to Figure 1), the reduction in temperature generated by the desorption mainly concerns the fluid, but avoids a significant reduction in the temperature of the materials. adsorbents. Coming out of the bed 14 of adsorbent material 9, the fluid reaches the annular outer volume 10. As the lower plate 12 comprises a passage means 7 of the fluid, the fluid can then passing through this passage means (which can be constituted by one or more orifices in the lower plate 12) join the lower bottom of the casing 13. It can then come out through the input/output means 6 to reach the I/O collection pipe. The heat is then stored in the molecules of the fluid and will be recovered during the next phase of discharge by the phenomenon of exothermic adsorption.

The coaxiality of the casing 13, of the bed 14 of adsorbent material 9 and of the distribution means 8 allows good distribution of the fluid in the device and in the bed 14 of adsorbent material 9, the pressure drops being radially balanced in the device. .

The device and the method described in FIG. 2 are particularly suitable when the adsorbent material comprises zeolite, when the fluid is air and when the molecules involved in the adsorption/desorption phenomena are water molecules, for example water vapour. Indeed, we can then use ambient air which contains more or less water vapour. This limits costs and avoids the risk of a lack of supply. Zeolite allows good adsorption/desorption of water, especially in the form of vapour. Thus, the system is simple and inexpensive.

Figure 3 illustrates, schematically and without limitation, a second embodiment of the device according to the invention. In this device, two beds 14 of adsorbent material are superimposed and arranged in a cylindrical casing 23. These two beds 14 are separated by a plate 22 sealed against the fluid. Thus, when the fluid passes radially in one of the beds, it cannot penetrate into the second bed via an axial path passing through the plate 22.

Each of the beds 14 separates an annular outer volume 26/27 and a central volume 24. The central volumes 24 of the two beds are connected to each other and allow free passage of the fluid from one of the central volumes to the other. In other words, there is no opening/closing means at the connection between the two central volumes 24. The central volumes 24 are cylindrical and of the same diameter, so as to limit pressure losses. . The central volumes 24 are connected to an inlet/outlet 21 allowing the supply or the collection of the fluid via a supply pipe or S/E collection.

The outer annular volumes 26 and 27 are not in communication. They are separated by the plate 22, fluid-tight. Each of these annular outer volumes 26 and 27 is delimited by the outer cylindrical envelope 23, comprising an upper flat bottom and a lower flat bottom, by the plate 22 and by the bed 14 of adsorbent material.

On either side of each of the beds 14 are positioned distribution means 25 constituted by porous walls at the level of the interface of each bed with the annular external volume 26 or 27 or with the central volume 24. Thus, the distribution means 25 are positioned on the external and internal cylindrical surfaces of each bed. The porous walls also allow the bed to be held in position, when the substantially cylindrical cylindrical casing 23 is positioned on the vertical or substantially vertical axis.

The distribution means 25 extend axially over the entire axial length of the beds 14, so as to ensure good distribution of the bed over the entire axial length. The distribution means therefore extend from the upper bottom, or the lower bottom, to the plate 22 separating the beds 14.

Each of the annular external volumes 26 and 27 is connected to an input/output means 19 allowing the introduction or the output of fluid from the annular external volumes 26 or 27. These input/output means comprise solenoid valves EV1 and EV2 ( a solenoid valve for each input/output means) so as to be able to control the fluid inlet or outlet in each of the annular external volumes 26 and 27. As a result, the openings can be controlled, for example successively, to optimize storage or heat recovery according to the various operating parameters (temperature, concentration of molecules, bed usage time to avoid heating of the adsorbent materials, type of adsorbent materials in the beds, etc.) and according to need. Alternatively, the solenoid valves can be opened simultaneously to cause the fluid to pass simultaneously through the different beds. This mode of operation allows the heat to be recovered more quickly. According to another alternative, it is possible to open then close the solenoid valves successively with an offset. In other words, the solenoid valve EV1 could be closed after the solenoid valve EV2 has been opened to better respond to certain operating situations.

The input/output means 19 are positioned on pipes 20 with a radial axis. These radial pipes 20 are interconnected by a pipe 18 with an axis parallel to the longitudinal axis of the cylindrical casing 23.

This pipe 18 is connected by a connection means 17 to an I/O supply or collection pipe. Thus, the same supply or collection makes it possible to introduce the fluid into the annular external volumes 26 and 27.

During the discharge phase D represented by the solid black arrows, the fluid arrives via the I/S supply pipe and is led via the pipes 18 and 20 to the inlet/outlet means 19 connected to each of the volumes external annular 26 and 27. Depending on the operating parameters and the need, the solenoid valves EV1 and EV2 are controlled simultaneously, successively or offset. The fluid is dispersed in the annular outer volume 26 and/or in the annular outer volume 27 by dispersion means 28 such as a baffle allowing the dispersion of the fluid both in the longitudinal direction and in the circumferential direction. The fluid then passes radially through the beds 14 of adsorbent material where the molecules it contains (air humidity for example) are adsorbed on the adsorbent material (zeolite for example). Heat is generated by this adsorption and is transmitted to the fluid. As the width of the bed 14 of adsorbent material is relatively short (compared to the prior art of Figure 1), the width being understood in the direction of passage of the fluid, that is to say radially for Figure 3 and longitudinally for Figure 1, the heat is very little transmitted to the adsorbent material, which makes it possible to limit the energy losses. Thus, the yield is improved. On leaving the bed 14, the fluid is hotter and less loaded with molecules (for example drier) than when it entered it. The heat can then be used exiting through the S/E collection pipe. Even if one of the solenoid valves EV1 or EV2 is closed, preventing the introduction of fluid into one of the two external annular volumes 26 and 27, the fluid, after having passed through the bed 14, finding itself in the central volume 24 will be evacuated to the S/E collection pipe, and will not pass through the bed 14 connected to the annular external volume 26 or 27 linked to the closed solenoid valve, because the pressure drops will prevent this passage.

This configuration is advantageous because the hot fluid is found in the central volume 24, which makes it possible to limit energy losses through the outer cylindrical envelope 23.

The cylindrical envelope 23, the beds 14 and the distribution means 25 are coaxial so as to distribute the fluid in a balanced and homogeneous manner and thus improve the performance of the device and of the method.

During the load phase R represented by the gray arrows in dotted lines, the fluid arrives through the supply pipe S/E and is introduced into the central volumes 24, the supply pipe S/E and the central volumes 24 have an identical or substantially identical internal diameter to reduce pressure drops. Depending on the operating parameters and the need, the solenoid valves EV1 and EV2 are controlled simultaneously, successively or offset. When one of the solenoid valves EV1 and/or EV2 is open, the fluid then passes radially through the bed 14 of adsorbent material in relation to this solenoid valve EV1 or EV2 via the annular external volume 26 or 27. The molecules which are contained in the material adsorbent (water molecules on the zeolite for example) are desorbed in the fluid (air for example). Heat is used during this desorption which is endothermic. In the loading phase, the adsorbent is regenerated with a hot stream to desorb the adsorbed molecule. Therefore, good heat transfer is required.

Leaving the bed 14, the fluid is colder and more loaded with molecules (for example more humid) than when it entered it. The heat is stored in the form of sensible heat and in the form of sorption enthalpy which can be restored during the subsequent adsorption phase. The fluid then emerges from the annular external volume 26 and/or 27 via the open solenoid valve EV1 and/or EV2 and is led through the pipes 18, 20 and I/O towards the fluid collection. The fluid can pass simultaneously in the two beds 14, successively in one then in the other or in a staggered manner (in this case, the solenoid valves EV1 and EV2 are momentarily open at the same time). When one of the solenoid valves EV1 or EV2 is closed, the fluid does not pass through the bed connected to this solenoid valve because pressure drops prevent it.

This configuration is advantageous because the fluid arrives hot in the central volume 24, which makes it possible to limit the energy losses through the outer cylindrical envelope 23.

Different operating modes are possible:

• Serial unloading of the different beds of adsorbent material: during the unloading period, the different beds are unloaded one after the other:
  • 1) Lower bed discharge: EV1 solenoid valve open, EV2 solenoid valve closed
  • 2) Upper bed discharge: EV2 solenoid valve open, EV1 solenoid valve closed
• Discharge by several beds at once, for example:
  • 1) discharge of the upper and lower beds: solenoid valves EV1 and EV2 open

It should be noted that depending on the mode of operation, it is quite possible to bring in the heat transfer fluid from above, in the discharge phase, and to let it out from below. Similarly, the regeneration fluid can enter from below and exit from above, during the charging period.

The embodiment of FIG. 3 offers the advantage of a wide operational flexibility compared to the prior art. Indeed, the latter offers the possibility of operating the different compartments or floors independently of each other by opening and/or closing the appropriate valves and thus benefiting from different thermal storage capacities, which can be used according to need. .

It also offers very good flexibility in operating conditions. For example, during the discharge period, the various stages of the device can be used in series one after the other, by opening and/or closing the appropriate valves, so as to benefit from the flow and operating conditions. optimal. For example, this mode of operation makes it possible to ensure a short contact time in the bed of adsorbent material and thus benefit from good use of the adsorbent material and ensure maximum efficiency of the device.

It should also be noted that in Figure 3, an embodiment with two stages is illustrated. Embodiments with more floors are quite possible.

Figures 2 and 3 illustrate embodiments where the envelopes are cylindrical and where the beds are annular in shape. Nevertheless, the envelopes could then have other shapes, for example of square, rectangular or hexagonal section, the beds would then be of similar shape and coaxial so as to ensure good distribution of the fluid in the bed or beds. Other forms could be used without departing from the scope of the invention.

To illustrate the advantages of the present invention, it is proposed to compare the results obtained by the invention (embodiment of FIG. 2) with those obtained by a thermal storage device according to the prior art (embodiment of figure 1). The performances of the two devices were estimated by numerical modeling of fluid mechanics, in English Computational Fluid Dynamics, coupled with the multi-physical phenomena encountered in the thermal storage device during the discharge phase.

To illustrate the advantage of the present invention, the operating conditions leading to optimum use of the zeolite bed (adsorbent material) during the discharge phase were determined by numerical modeling. The case of a sorption heat storage device implementing a volume of zeolite of 41.4 m ³ is dimensioned. The duration of the discharge period is 16 h. The performance gains in terms of pressure loss generated by the two devices are then compared.

Property of the column according to the prior art:

• Height of the zeolite bed: 4.3 m
• Bed diameter: 3.5 m
• Heat transfer medium: air
• Moist air flow: 4.74 kg/s
• Water vapor concentration: 3.55 mol/m ³
• Pressure: 1 atm
• Entry temperature: 59°C
• Zeolite type: 13X
• Zeolite particle diameter: 3.75 mm
• Bed void ratio: 0.318
• Zeolite volume: 41.37 m ³
• Duration of the discharge phase: 16h

Property of the storage device according to the invention:

• Height of the zeolite bed per floor: 4.3 m
• Column diameter: 3.635 m
• e=0.05m
• L=1.518m
• di=0.5 m
• Moist air flow: 4.74 kg/s
• Water vapor concentration: 3.55 mol/m ³
• Pressure: 1 atm
• Entry temperature: 59°C
• Zeolite type: 13X
• Zeolite particle diameter: 3.75 mm
• Bed void ratio: 0.318
• Zeolite volume: 41.37 m ³
• Duration of the discharge phase: 16h

The performances obtained are presented in the following table:

The efficiency η corresponds to the efficiency of the device obtained in 16 hours of discharge. ΔP max corresponds to the maximum pressure drops reached during the 16h discharge cycle.

This example clearly shows that the use of the present invention allows better performance in terms of pressure loss compared to the device of the prior art. Indeed, the invention makes it possible to guarantee optimal efficiency of thermal energy discharge while significantly reducing pressure drops compared to the prior art. A reduction of 87% is obtained.

This significant gain makes it possible on the one hand to reduce the investment and operating costs of the heat storage device according to the invention and on the other hand also offers the flexibility to increase the size of the device or/and reduce the size of the zeolite particles and/or increase the loading density and thus further increase the storage capacity and the efficiency of the device.

Claims (16)

Thermal storage device by sorption of a fluid on an adsorbent material, the device comprising an envelope (13, 23), at least one external volume (10, 26, 27) and at least one central volume (15, 24), said external (10, 26, 27) and central (15, 24) volumes being included in said envelope (13, 23) and being separated by at least one bed (14) of said adsorbent material (9), at least one first means input/output (6, 19) of said fluid being connected to said at least one central volume (15, 24), at least one second input/output means of said fluid being connected to said at least one external volume (15, 24 ), each bed (14) of adsorbent material (9) being delimited by a lower plate (12) and by an upper plate (11), characterized in that the said lower (12) and upper (11) plates are integral with the said casing (13, 23) and in that said lower (12) and upper (11) plates are sealed to said fluid. Device according to Claim 1, for which the adsorbent material (9) comprises at least one zeolite. Device according to one of the preceding claims, in which said envelope (13) is a cylindrical envelope and said external volume (10, 26, 27) is an annular volume. Device according to one of the preceding claims, for which the bed (14) of adsorbent material (9) comprises on its internal periphery and/or on its external periphery a means (8, 25) for distributing the fluid. Device according to Claim 4, for which the fluid distribution means (8, 25) comprises a porous wall or a wall comprising regularly distributed holes or orifices. Device according to one of the preceding claims, for which dispersion means (28) are positioned in the outer volume (10, 26, 27) and/or in the central volume (15, 24). Device according to one of the preceding claims, for which the device comprises several beds (14) of adsorbent material (9), the said central volumes (24) of the said beds (14) of adsorbent material (9) being connected to each other. Apparatus according to claim 7, wherein each of the second fluid inlet/outlet means comprises a solenoid valve, said second fluid inlet/outlet means being connected to a common fluid supply. Device according to one of the preceding claims, in which the device comprises several storage stages, each storage stage comprising an external volume (26,27), a central volume (24) and a bed (14) of adsorbent material (9 ) separating the outer volume (26, 27) and the central volume (24), preferably, the storage floors being superposed. Process for storing heat by sorption of a fluid on an adsorbent material, in which the following steps are carried out:
- in the discharge phase:
* the fluid loaded with molecules to be adsorbed is made to enter one of the outer (10, 26, 27) or central (15, 24) volumes of said storage device according to one of claims 1 to 9 by one of the inlet means /output (6, 19),
* the fluid is passed transversely, preferably radially, into the bed (14) of adsorbent material (9), on which said fluid is adsorbed, releasing the molecules to be absorbed and releasing heat transmitted to the fluid, advantageously to a temperature between 50 and 300°C, preferably between 50 and 250°C, very preferably between 90 and 220°C,
* said hot fluid, discharged from the adsorption molecules of the bed (14) of adsorbent material (9), is brought out by the other of said external (10, 26, 27) or central (15, 24) volumes of said storage device ;
* Said hot, dry fluid is brought out of said storage device by the other of said input/output means (6, 19). Process for storing heat by sorption of a fluid on an adsorbent material, in which the following steps are carried out:
- in charging or regeneration phase:
* the fluid, preferably hot and free of adsorption molecules, is introduced into one of the outer (10, 26, 27) or central (15, 24) volumes of said storage device according to one of claims 1 to 9 by one of the input/output means (6, 19),
* the fluid is passed transversely, preferably radially, in the bed (14) of adsorbent material (9) in which the fluid desorbs the molecules adsorbed during the discharge phase by storing the heat,
* said fluid loaded with adsorption molecules is brought out of the bed of adsorbent material by the other of said external (10, 26, 27) or central (15, 24) volumes of said storage device,
* said fluid laden with adsorption molecules is brought out from said storage device by the other of said input/output means (6, 19). Process for storing heat by sorption of a fluid on an adsorbent material, in which the steps of claim 10 are carried out during the discharging phase and in which the steps of claim 11 are carried out during the charging phase. Method according to claim 10 to 12, in which the fluid is distributed through the bed (14) of adsorbent material (9). Method according to one of Claims 10 to 13, in which the fluid is dispersed in the external volume (10, 26, 27) and/or in the central volume (15, 24). Process according to one of Claims 10 to 14, for which the fluid is air and the molecules are water molecules. Method according to one of Claims 10 to 15, in which the fluid is caused to enter the various beds (14) of adsorbent materials (9).