FLUIDIZED BED HEAT EXCHANGER AND METHOD

Abstract

An apparatus (100) for the accumulation and transfer of thermal energy, comprising: # a thermal energy charging device (1), having a bed of fluidizable solid particles received within a housing and acting as a heat accumulation medium when exposed to a thermal energy source; # countercurrent heat exchange means (3), configured for thermal energy exchange between a heated vector mass of said bed particles and an operating fluid; # transport means (5) configured to feed said vector mass of said bed particles from said device (1) to said heat exchange means (3) and to return at least a portion of said subsequent vector mass from said heat exchange means (3) to said device (1); # a control unit (10) associated with parameter sensing means (6).

Description

FLUIDIZED BED HEAT EXCHANGER AND METHOD Field of invention The present invention relates primarily to a device, system, and method for the accumulation and transfer of thermal energy. In particular, the Invention uses thermal energy storage devices based on a bed of solid particles that can be fluidized. Background of the invention Devices for the accumulation and transfer of thermal energy based on a fluidized or fluidizable bed of solid particles are known in the art. In the systems mentioned above, the heat exchangers are immersed in the particle bed. These exchangers can be based, for example, on tube bundles through which an operating fluid, such as steam or CO2, flows. In its simplest configuration, the particle bed can be assumed to be isothermal, that is, a mass where each and every particle has the same temperature. This approximation is acceptable due to the high thermal diffusivity throughout the fluidized bed. Under these conditions, thermal energy is stored in the bed as sensible heat from the solid particles, given by Q=m*cp*ΔT [1], where: O is the thermal energy stored in the fluidized bed, m is the total mass of the bed particles, and cpes is the specific heat capacity of the particles. ΔT is the temperature difference of solid particles (Tmax-Tmin), where Tmin and Tmax are respectively the minimum and maximum operating temperatures of the bed particles during heat exchange. Given the above, when the bed has been charged with thermal energy, i.e., when it has been heated, such energy can be transferred to a heat transfer fluid (HTF), such as steam, CO2, supercritical CO2 and the like, by means of said heat exchangers submerged in the bed. The temperature produced in the HTF is, of course, always lower than the bed temperature and can be adjusted (for example, by means of so-called steam de-temperators) to meet the desired conditions for use. For better understanding, the diagrams in FIGS. 1 to 3 show possible temperature trends of the bed mass (e.g., made of sand particles) and of the heat transfer fluid (e.g., steam), in a case where Tmin is assumed to be 350°C, Tmax to be 620°C and the steam generation time is 6 hours. In particular, FIG. 1 shows a steadily decreasing steam temperature along with the decreasing temperature of the solid particles, while FIG. 2 shows a generation profile QL / cnn / eznz / e / Y of steam at 500°C during the first two hours and then decreases along with the decrease in the temperature of the solid particles, while FIG. 3 shows a steam generation profile at a constant 300°C throughout the period. It is important to note that the diagrams above show that, in all cases, HTF occurs, at least for a period of time, at a temperature below the minimum temperature of the fluidized bed (in the example shown Tm / n=350°C). In other words, for an application where HTF is needed at, for example, 500°C constantly, the solution shown above cannot work unless the minimum particle temperature is increased above 500°C (for example, to 530°C). However, this increase in Tmin would have a strong negative impact on thermal storage capacity, as the operational ΔT of solid particles would be significantly reduced. To continue with the previous example, JT would decrease from (620-350)°C=270°C to (620-530)°C=90°C, meaning that the thermal storage capacity would be reduced by 1 / 3 if the steam is to be produced at 500°C instead of 300°C. Theoretically, this gap could be bridged by increasing the maximum fluidized bed temperature (Tmax), but this increase may not be feasible (and / or economical), particularly due to the operating limitations of the materials used in heat exchangers. Referring again to the previous example, to consistently produce steam at 500°C, adopting a minimum fluidized bed temperature (Tm / f7) of 530°C and maintaining the same thermal energy storage capacity, the maximum fluidized bed temperature would need to increase from 620°C to 800°C (i.e., 530+ / iT=530+270=800°C), which may prove impractical given the limitations of the heat exchanger materials. Another possible countermeasure to maintain the same thermal storage capacity, when steam is produced at a higher temperature (e.g., 500°C), would be to increase the mass of solid particles, but again, that would involve much larger modules (in the example, three times larger), with a significant increase in costs. The above considerations are even more important in the case of supercritical CO2, which is currently expected to be able to drive a turbine with an estimated thermal-to-electrical efficiency of up to 50%, on the condition that the supercritical CO2 is delivered to the turbine at a temperature above 700°C (and a pressure above 200 bar). In these cases, the fluidized bed must be working in a very high temperature range (for example, from 730°C to 1000°C), which, even if possible for solid particles, could make the construction of submerged heat exchangers unfeasible, or their lifespan too short, due to the aforementioned material limitations. Therefore, there is a need for devices, systems, and methods based on fluidized bed particles that allow for the accumulation and exchange of thermal energy in a more efficient manner, particularly in certain fields of application. QL / cnn / eznz / e / Y Brief description of the invention The technical problem posed and solved by the present invention is, therefore, to provide a heat storage and transfer configuration based on a fluidized bed of solid particles that allows overcoming one or more of the drawbacks or criticalities mentioned above with reference to the known art. An objective of the present invention is to provide a device, apparatus, system and / or method for accumulating and transferring energy in thermal form that is particularly effective, especially for ensuring the continuous generation of high-temperature heat transfer fluid for the supply of electrical or thermal energy to an end user. According to another aspect, the present invention aims to overcome some performance limits intrinsically associated with the heat transfer mechanism of a thermal energy accumulator formed by a fluidized bed of solid particles equipped with heat exchangers immersed in the same particle bed exposed to a thermal energy source. The aforementioned objectives are achieved by means of an apparatus according to claim 1 and by means of a method according to claim 13. The preferred features of the invention are listed in the dependent claims. The invention is based on a device that allows the accumulation of energy, in thermal form, in a bed of fluidized solid particles and a simultaneous or delayed transfer of the accumulated energy to an operating fluid. The configuration of the invention allows for efficient and flexible use of the outgoing energy according to the needs of an end user. Advantageously, the stored energy can be transformed into electrical energy, used directly in thermal form, or even used in a combination of these two forms in industrial applications (CHP, Combined Heat and Power Plants). The invention is applicable to the so-called "concentrated solar energy" configuration, where thermal energy is loaded into the storage bed by means of solar rays, i.e., by solar radiation falling on it, either directly or indirectly, for example after one or more reflections or re-irradiations, with or without means, for example transparent screens, interposed between the bed and the solar source / radiation. Compared to other concentrated solar power solutions based on solid particles, the fluidized bed technology-based solar receiver / heat storage device offers a buffering time for heating the particles, with a greater capacity to ensure temperature control of the solid particles, for higher performance and operational safety. This feature is particularly important during abrupt transients in solar energy input to the receiver device, such as the sudden appearance or disappearance of clouds, or in any case for handling solar radiation that varies throughout the day: the fluidized bed of solid particles acts as a thermal flywheel, enabling excellent heat transfer, high heat capacity with a homogeneous temperature field, and is capable of absorbing thermal shocks, not only due to the QL / cnn / eznz / e / Y resistance to temperature of solid particles, but also thanks to the continuous mixing of fluidized solid particles, which provides high thermal diffusivity, continuous renewal of the material exposed to concentrated sunlight and sufficient residence time to bring the particles to the desired temperature level for use. The invention is also applicable to a configuration in which thermal resistances or thermally equivalent means are immersed in, or in thermal connection with, the fluidized bed of particles; that is, in which the thermal energy load on the bed is achieved by the Joule effect (and therefore by electricity), by a hot heat transfer fluid, by waste heat, or combinations thereof. In particular, these bed heating means may utilize low-cost electrical energy, for example, from a renewable source, particularly wind or photovoltaic, or waste thermal energy, i.e., thermal waste from industrial processes. The invention is also applicable to hybrid solutions, where the thermal energy load on the bed is produced by combining different energy sources, such as sunlight, electricity, heat transfer fluid, waste heat, or others. The advantages, features, and additional uses of the present invention will become evident from the following detailed description of some embodiments thereof, described by way of example and not for limiting purposes. Brief description of the drawings Reference will be made to the figures in the attached drawings, where: Figures 1 to 3 show diagrams that have already been introduced in the “Background” section of this description. FIG. 4 shows a block diagram illustrating a conceptual scheme of one embodiment of a heat exchange and thermal energy storage apparatus according to the present invention. FIG. 4A shows a block diagram illustrating a conceptual scheme of one modality of a heat exchange and thermal energy storage system according to the present invention, which is based on the arrangement shown in FIG. 4. FIG. 5 shows a block diagram illustrating a conceptual scheme of another modality of a heat exchange and thermal energy storage apparatus and system according to the present invention. FIG. 6 shows a side view of one embodiment of a heat exchange and thermal energy storage apparatus according to the present invention, which is based on the arrangement shown in FIG. 4. FIG. 7 shows a side view of another embodiment of a heat exchange and thermal energy storage apparatus according to the present invention, which is based on the arrangement shown in FIG. 4. Figures 8A and 8B show a side and top view, respectively, of another embodiment of a heat exchange and thermal energy storage apparatus according to the present QL / cnn / eznz / e / Y invention, which is based on the arrangement shown in FIG. 4. FIG. 9 shows a side view of a possible way of reintroducing solid particles into a fluidized bed in the presence of highly concentrated solar radiation, according to an embodiment of the present invention, which is based on the arrangement shown in FIG. 4. Detailed description of the invention The following will describe modalities and variants of the invention, with main reference to the figures mentioned above. In the following detailed description, additional modalities and variants with respect to the modalities and variants already discussed in the same description will be illustrated only along with the differences with respect to what has already been illustrated. On the other hand, the various modalities and variants described below, as well as the related components, means and elements, may be used in combination, when they are compatible. A heat exchange apparatus 100 according to a preferred embodiment of the invention is conceptually illustrated in FIG. 4. The apparatus 100 includes a receiver device 1, or receiver, for capturing and stabilizing the temperature of thermal energy in a fluidized bed of solid particles. This device is referred to as the “receiver” in Figure 4. Heat is supplied to the bed by an energy source (“energy” in Figure 4), for example, solar radiation or another energy source. These latter sources may include, for example, electrical resistors, immersed in the bed or in thermal connection with it, as described in the “Brief Description of the Invention” section of this description. The general configuration of device 1 may be as described, for example, in WO201 7 / 021832A1, WO2018 / 142292A1, WO2013 / 150347A1 or W02020 / 136456A1. Downstream of device 1, with respect to the physical flow of solid particles, is a heated tank 2 that receives a physical flow of the heated particles comprising the bed of device 1. The heated tank 2 serves to accumulate heated particles for the desired time; its capacity allows for the storage of the desired thermal energy. The particles that physically move from device 1 to heated tank 2 can be the entire bed housed in device 1 or a portion thereof. The bed can be configured so that a resident mass remains in device 1 at all times, while another vector mass moves toward heated tank 2 and the subsequent elements of apparatus 100. The volumes comprising these two masses can also be adjusted or selected according to energy requirements.As mentioned above, in preferred applications, the resident mass is zero, meaning that the entire bed moves in the thermal circuit as described in this document. In specific configurations, the fluidized bed level in device 1 can vary, or be adjusted, during operation, between a maximum and a minimum level, to compensate for possible differences between the rate of solid particles entering and leaving the receiver. Subsequent flow of hot tank 2 with respect to the heat exchange flow and physical flow of QL / cnn / eznz / e / Y particles are located in a heat exchanger 3. Therefore, in the present configuration, the heat exchanger 3 is not immersed in the fluidized bed, but is located on the outside of device 1. Heat exchanger 3 can be based on a heat transfer fluid (HTF), for example, steam or (supercritical) CO2. Preferably, heat exchanger 3 operates in countercurrent flow, meaning the bed particles and the HTF flow in opposite directions within the exchanger 3. Heat exchanger 3 may include a plurality of units, which also operate according to different principles or exchange fluids. Subsequent to the heat exchanger 3, there is a cold tank 4, which receives the cold solid particles after they have given up heat to the HTF. The apparatus 100 further comprises means for circulating the vector mass of bed particles from device 1 to components 2 to 4 introduced above and back to device 1. Such means are represented schematically by arrows in FIG. 4 and globally indicated by 5. They may be based, for example, on mechanical conveyors, gravity feed, elevators, or other means. A local or remote control unit 10 of the apparatus 100 can control or command the various elements introduced above and determine the operating modes and / or parameters related to particle flow and heat exchange. The control unit 10 can be configured to control the flow of said vector mass within the apparatus based on pre-programmed parameter values ​​and / or values ​​detected by parameter sensing means 6, arranged in one or more selected locations of the apparatus 100. In particular, the control unit 10 can adjust the mass flow rates of particles entering and exiting the device 1, according to the available energy input, to maintain the detected fluidized bed temperature within the desired range. Likewise, the control unit 10 can be configured to control the operation of the heat exchanger 3, specifically by adjusting the mass flow rate of solid particles passing through the heat exchanger, according to the HTF mass flow rate and the desired operating temperature. Advantageously, all elements of the equipment, for example of device 1, the hot and cold water tanks 2, 4, the heat exchanger 3 and the corresponding transfer media are thermally insulated to limit heat losses. The general operating modes of the device 100 are illustrated below. As explained above, the solid particles, or a vector mass thereof, are not contained in device 1 permanently, but are transferred, in sequence, from device 1 to hot tank 2, to heat exchanger 3, to cold tank 4 and finally recirculated in device 1. The solid particles are heated in device 1, for example by solar source, electricity, process heat or other means. QL / cnn / eznz / e / Y When the solid particles have reached the desired maximum temperature in device 1, i.e., when thermal energy has been charged into the fluidized bed, the solid particles are extracted, in a batch / discrete or continuous mode, from device 1 and transported to tank 2. The temperature field of the fluidized bed of device 1 can be continuously monitored by means of dedicated thermocouples 6 or other temperature sensors or transducers, preferably in communication with the control unit 10, to allow the discharge of solid particles into the hot tank 2 when its temperature has reached the desired value, optimal for the operation of the heat exchanger 3. The hot tank 2 is sized to ensure the desired thermal energy storage capacity. When energy is to be released to the HTF, the solid particles are transferred from hot tank 2 to the external heat exchanger 3. The thermal energy stored in hot tank 2 can be released during a simultaneous thermal energy loading phase occurring in device 1, depending on the mass of the resident bed, or at a later time, according to the specific process requirements. The external heat exchanger 3, preferably in a countercurrent configuration, receives the hot solid particles, and the HTF exits the heat exchanger 3 at a temperature slightly lower than the temperature of the hot particles entering the receiver. For example, referring to the example illustrated in the "Background of the Invention" section of this description in conjunction with supercritical CO2, the latter can be produced at 700°C, with the solid particles at, for example, 720°C as the maximum temperature, thus resolving the criticalities highlighted with reference to the prior art. The solid particles, after having given up their heat content to the HTF, leave the external heat exchanger 3 at a “cold” temperature and are delivered to the cold tank 4, for example, as mentioned above, by gravity, by mechanical extractors, or by other means. The cold tank 4 receives the solid particles during HTF generation and can store the particles until the next heating phase begins in device 1. The cold tank 4 is preferably at least the same size as the hot tank 2, so that the heat content associated with the entire mass of particles stored in the hot tank 2 can be released to the HTF in the heat exchanger 3. Finally, the solid particles are recirculated, through medium 5, from the cold reservoir 4 to device 1, where they are heated again by the power supply. During the recirculation of solid particles to device 1, preheating of solid particles can be provided, for example, by electric heaters, radiant burners or other heating means located, for example, within conveyor belts. According to the preferred control modes, the mass flow rate of solid particles to be recirculated to device 1 is adjusted according to the actual amount of input energy entering the device. Such control can be performed by the control unit 10, for example, by means of a QL / cnn / eznz / e / Y frequency converter that regulates the speed of a mechanical extraction system from the cold storage tank. When the available input power for device 1 increases / decreases, the flow rate of recirculated particles in device 1 can increase / decrease proportionally, helping to maintain the temperature of the solid particles within the device within the desired temperature range. According to one configuration, device 1 and hot reservoir 2 can be integrated into a single unit or the hot reservoir can be omitted. This configuration can be useful, for example, if the HTF is not generated simultaneously with the energy input to device 1, but only at a later stage. In this alternative configuration, the cold solid particles recirculated from cold tank 4 to the integrated fluidized bed receiver / hot tank device, or just to receiver 1, fill it before the next energy loading phase begins, in particular without mixing of cold particles with hot particles during HTF generation. If the device is charged with solar energy, as in a concentrated solar power system, solar radiation can be introduced into the fluidized bed receiver directly from a heliostat field or through secondary reflection, for example by a downward beam mirror. According to a preferred embodiment of said receiver device 1 shown in FIG. 9, the recirculation of solid particles to the receiver can be carried out in such a way that the solar radiation 200 entering the receiver, preferably through a window 201 in a side wall, impinges on the solid particles 203 as they fall into the device. In this way, the internal linings of the receiver 204 are protected from particularly intense radiation fluxes, and an initial heating of the particles is achieved before they reach the rest of the fluidized bed 205, where their heating continues and is completed until the particle temperature reaches the desired value for use. Even in the case of a concentrated solar system, the power entering the receiver can be estimated at any time by measuring the actual solar radiation (e.g., DNI, Direct Normal Irradiance) in the heliostat field using conventional instrumentation, e.g., a pyrheliometer, and processing it using known optical performance algorithms. If the receiver is charged with thermal energy from electricity (Joule effect), the input power can be estimated using conventional instrumentation, such as wattmeters; furthermore, if the receiver is charged with heat using hot fluid, the input power can be derived from conventional measurements of hot gas flow rate and temperature / pressure. According to a preferred embodiment of a heat exchange and thermal energy storage system, a plurality of devices or modules, such as those illustrated in FIG. 4, can be arranged in parallel, as conceptually shown in FIG. 4A, where such devices are denoted by 101, 102, ..., 10N, respectively. In this embodiment, the HTF flows QL / cnn / eznz / e / Y hot A1, A2, ..., AN produced by each module are delivered together to an end user. According to another embodiment of a heat exchange and thermal energy storage system, exemplified in FIG. 5, a plurality of devices, or modules, 111, 112, ... 11N can be integrated with each other, having a common heat exchanger 30. In this case, the solid particles from each hot tank or from each receiver of the respective devices are transported to the common heat exchanger 30 as flows C1, C2, CN, and from there are recycled back as flows B1, B2, BN to each respective cold tank. The system configuration shown in Figure 5 can be advantageously used when the heat exchanger must be located close to the hot HTF (High Temperature Transformer) area. For example, in the case of electricity generation using a supercritical CO2 turbine, the supercritical CO2 must be produced at high temperatures and high pressures (above 700°C and 200 bar, respectively) to enable highly efficient conversion cycles. These conditions require the use of special materials capable of withstanding the severe thermomechanical stresses resulting from the combination of high temperature and pressure, particularly in the heat exchanger and the supercritical CO2 piping from the heat exchanger to the supercritical CO2 turbine. The length of these pipes can thus be minimized by the proposed configuration, reducing the risk of potential failures and excessive costs. Therefore, again, in FIG. 5 a heat exchanger 30 common to several devices is used, so that, in selected applications, it can be located just close to the supercritical CO2 turbine, thus minimizing the relevant pipe length, while the solid particles are transported to and from the heat exchangers by means of, for example, mechanical conveyors, gravity, or other means. The following will describe preferred modes for one or more elements of the circulation means 5 represented schematically by arrows in FIGS. 4 to 5. Reliable transport of solid particles is preferably achieved by means of a high-temperature resistant mechanical conveyor, preferably completely enclosed in an outer casing and / or thermally insulated to limit heat loss to the environment. Examples of suitable conveyors, in particular belt conveyors, may be based on the general configurations described, for example, in W02007 / 034289A1 or WO2017 / 013517A1. Figure 6 shows one configuration of the apparatus, indicated as 100', based on the conceptual scheme in Figure 4. In this example, receiver 1, hot tank 2, and heat exchanger 3 are arranged in a tower configuration, while cold tank 4 is positioned to one side, thus limiting the height of the tower. Preferably, the transport of solid particles from the exchanger 3 to the cold tank 4 and from the latter back to the receiver 1 is achieved by a combination of respective inclined conveyors indicated by 51 and 52. As an example of dimensioning a device and system associated with the configuration of FIG. 6, the following is observed. QL / cnn / eznz / e / Y According to the diagram in FIG. 6, the apparatus incorporates a fluidized bed receiver, a hot tank, a cold tank, and a supercritical CO2 (sCO2) heat exchanger, which produces sCO2 that drives a Brayton power cycle turbine (not shown in FIG. 6) for electricity generation. Supercritical CO2 turbines are being developed with the aim of achieving a thermal-to-electrical conversion efficiency close to 50%, provided that the sCO2 is produced continuously at a temperature of around 700–720°C (and a pressure above 200 bar). Assuming a certain power output for the CSP plant, for example, for electricity generation throughout the day, i.e., even in the absence of sun, the hot and cold water tank will have sufficient capacity to store the solid particles to ensure power generation at night, while the receiver must be able to capture solar energy during the day, and then release it throughout the day to the sCO2 circuit, and the solid particle recirculation system must be sized to handle the necessary mass flow rate. Assuming, for example, a power output of 3 MWe, electricity generation 24 hours a day (8 daytime hours plus 16 nighttime hours), solid particles with a specific heat capacity of 1200 J / kgK, sCO2 turbine efficiency of 47%, solid particles countercurrent sCO2 heat exchanger with a solid particle temperature drop of 200°C (e.g., 750°C to 550°C) and efficiency of 95%, receiver efficiency of 85%, it follows that: Receiver 1 must be sized to receive an average of 23.7 MWt of solar energy during the day; Heat exchanger 3 must be traversed by 101 t / h of solid particles continuously, throughout the day; The inclined conveyor 51 will handle a mass flow rate of solid particles of 101 t / h, at 550°C; Hot tank 2 and cold tank 4 must guarantee a minimum capacity of 1613 tons, with material temperatures of 750°C and 550°C respectively (neglecting minor heat losses during transport); The inclined conveyor 52 will transport a solid particle rate of 303 t / h from cold tank 4 to receiver 1 during the day, at 550°C. In this way, receiver 1 will be fed with solid particles at a rate of 303 t / h during the day, and will discharge 303 t / h to the heated tank 2 via a dosing system (not shown in FIG. 6). Assuming, for example, a receiver capacity of 300 tons, the solid particles will have almost 1 hour to heat up under the average solar power of 23.7 MWt. This time is much longer than other CSP solid particle technologies and, thanks also to the high thermal diffusivity of the fluidized bed and the possibility of monitoring the particle temperature in real time, for example by means of thermocouples immersed in the fluidized bed, the proposed configuration allows for much greater temperature stabilization and better control of the solid particles within the desired temperature range, before they are fed into the QL / cnn / eznz / e / Y hot tank and then to the heat exchanger. Proper control of the solid particle temperature is critical for the safe operation and high performance of the sCO2 circuit. FIG. 7 shows an alternative arrangement of one type of apparatus, indicated by 100'', still based on the conceptual scheme of FIG. 4, in which receiver 1, hot tank 2 and heat exchanger 3 are all arranged in a tower configuration. This option is particularly suitable for plants where the height of the tower is not a problem and the horizontal occupation of the land must be minimized. The downward transport of solid particles from the various elements can be achieved by mass flow control devices and / or by gravity, for example, metering valves interposed between adjacent elements 1-2, 2-3 and 3-4. The upward return transport of solid particles can be achieved, for example, by a vertical elevator 53. FIGS. 8A and 8B show an additional modality of an apparatus configuration, indicated herein by 100”', which may still be considered as generally based on the conceptual scheme of FIG. 4 or 4A. In this configuration, thermal energy is loaded into one or more fluidized bed receivers, specifically four receivers indicated by 11 to 14 in the example shown. The accumulated thermal energy is then delivered, by the discharge of respective masses of hot solid particles, to a common set of heat exchanger 300 and cold tank 400. Common or separate hot tanks, optionally integrated into the respective receivers, may also be provided. Even in the illustrated example, mechanical conveyors can be used to transfer the particles to the exchanger 300. Two of these are indicated, by way of example, as 501 and 502 in FIG. 8A. Likewise, mechanical conveyors and elevators, indicated by 21 to 24, can be used to recirculate the cold solid particles from the cold tank 400 to the four receivers 11 to 14. In the configuration with associated or integrated hot tanks in the respective receivers 11 to 14, the apparatus 100" captures and stores thermal energy in the fluidized bed receivers during the loading phase, keeping the solid particles contained in the receivers / tanks hot, and releases the relevant particle masses later, during the HTF generation phase. The feeding of the particle mass from the respective receivers 11 to 14 to the common heat exchanger 300 can be simultaneous or not, depending on the specific energy generation requirements and the plant configuration. Cold tank 400 can have at least the same capacity as the total capacity of receivers 11 to 14, to hold all the vector particle masses before the next loading phase begins. Therefore, the 100" apparatus is suitable for use when thermal energy is charged into the receivers and heat is exchanged in the 300 exchanger, i.e., HTF generation, are not contemporaneous. For example, this configuration can be adopted to capture solar energy in a concentrated solar power system during the day and produce HTF at a delayed time, typically after QL / cnn / eznz / e / Y sunset. In addition, this configuration can be used to charge energy (e.g., provided by electricity, waste heat, or other sources) into the fluidized bed when energy is available at low cost, to be released at a later time, not simultaneously with the charging phase. In other words, according to a preferred operating mode, the cold particles from the cold reservoir are not recirculated to the fluidized bed receivers during the energy loading phase or, in any case, the energy loading and energy exchange phases are shifted in time. The invention further provides a method for accumulating and transferring thermal energy, based on the functionalities already described above in relation to the apparatus and system of the invention. The objective of the present description has thus far been described with reference to its preferred embodiments. It should be understood that other embodiments belonging to the same inventive principle may exist, all of which fall within the scope of protection of the claims reported below.

Claims

1. An apparatus (100) for the accumulation and transfer of thermal energy, comprising: at least one thermal energy charging device (1), having a fluidized bed of solid particles received within a housing and acting as a heat accumulation medium when exposed to a thermal energy source; heat exchange means (3), configured for thermal energy exchange between a heated vector mass of said bed particles and an operating fluid, said heat exchange means (3) being configured for countercurrent exchange; transport means (5), configured to feed said vector mass of said bed particles from said energy charging device (1) to said heat exchange means (3) and to return at least a portion of said vector mass subsequently from said heat exchange means (3) to said energy charging device (1);parameter detection means (6) arranged at one or more selected points of the apparatus (100) and comprising temperature sensors;and a control unit (10), configured to control the flow of said vector mass within the apparatus on the basis of pre-programmed parameter values ​​of parameter values ​​detected by said parameter detection means (6), wherein said control unit (10) is configured to adjust the mass flow rates of particles entering and leaving said energy loading device (1) according to the available input power in order to maintain a detected value of the fluidized bed temperature within a desired range, and wherein said control unit (10) is configured to control the operation of said heat exchange means (3) by adjusting the mass flow rate of solid particles passing through the heat exchange means (3) according to the operating fluid mass flow rate and the desired temperature for its use.

2. The apparatus (100) according to claim 1, wherein said energy charging device (1) is configured to heat said bed particles by solar radiation, directly or indirectly impacting said bed particles, with or without screen means interposed between them.

3. The apparatus (100) according to claim 1 or 2, wherein said energy charging device (1) is configured to heat said particle bed by electrical means, in particular by means of one or more resistors immersed in or in thermal connection with the particle bed and heating them by Joule effect.

4. The apparatus (100) according to any of the preceding claims, comprising a hot reservoir (2) disposed subsequently of, or integrated into, the energy charging device (1), and configured as a storage container for the QL / cnn / eznz / e / Y vector mass interposed between the energy charging device (1), or a part thereof exposed to the energy source, and the heat exchange means (3).

5. The apparatus (100) according to any of the preceding claims, comprising a cold tank (4) subsequently disposed of the heat exchange means (3) and configured as a storage container for the vector mass interposed between the heat exchange means (3) and a portion of the transport means (5) that returns the vector mass to said energy charging device (1).

6. The apparatus (100') according to any of the preceding claims, wherein said or each energy charging device (1), said hot reservoir (2), said heat exchange means (3) and / or said cold reservoir (4) have a tower arrangement, with one or more energy charging devices (1) at the top and the other elements below them.

7. The apparatus (100) according to claims 5 and 6, wherein said cold tank (4) is arranged laterally with respect to said or each power charging device (1), said hot tank (2) and / or said heat exchange means (3).

8. The apparatus (100') according to any of the preceding claims, comprising a plurality of thermal energy charging devices (11-14), each of which has a respective fluidized bed of solid particles received within a housing and acting as a heat accumulation means when exposed to a thermal energy source.

9. The apparatus (100'“) according to the preceding claim, comprising heat exchange means (300) and / or cold tank (400) common to the plurality of thermal energy charging devices (11-14) and configured to be selectively fed by one or more respective vector masses of said devices.

10. The apparatus (100') according to any of the preceding claims, wherein said heat exchange medium (3) is configured to operate with steam, CO2 or supercritical CO2 as the operating fluid.

11. The apparatus (100) according to any of the preceding claims, wherein said means of transport (5) comprises one or more mechanical conveyors (51, 52), preferably belt conveyors, and / or one or more lifting devices.

12. A system for the accumulation and transfer of thermal energy, comprising a plurality of apparatuses (101, 102) each in accordance with any of the preceding claims, arranged in parallel with respect to a flow of said operating fluid.

13. A method for accumulating and transferring energy in thermal form, providing the following steps: a thermal energy charging step, wherein a fluidized bed of solid particles is exposed to an energy source; a heat exchange step, wherein at least a vector mass of said heated bed particles is circulated in countercurrently operating heat exchange means to transfer heat to an operating fluid; and a step for transporting said vector mass back to said charging step;wherein the flow of said vector mass is controlled on the basis of preprogrammed and detected parameter values ​​including temperature, wherein the mass flow rates of particles entering and leaving said energy loading stage are adjusted according to the available input power to maintain a detected value of the fluidized bed temperature within a desired range, and wherein said heat exchange step is controlled by adjusting the mass flow rate of solid particles of the vector mass circulating to the heat exchange means according to the operating fluid mass flow rate and the desired temperature for its use.

14. The method according to the preceding claim, wherein said energy source is a solar energy source.

15. The method according to claim 13 or 14, wherein said energy source is an electrical energy source, for example electrical energy from renewable sources, or a residual thermal energy source, for example thermal waste from other industrial plants.

16. The method in accordance with any of claims 13 to 15, wherein said operating fluid is steam, CO2 or supercritical CO2.

17. The method according to any of claims 13 to 16, wherein a thermal energy charging step is simultaneous with a heat exchange step.

18. The method according to any of claims 13 to 17, wherein said heat exchange step is deferred with respect to any thermal energy charging step.

19. The method according to any of claims 13 to 18, using an apparatus or system according to any of claims 1 to 12.

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