IT201700010806A1 - HIGH LEVEL DEVICE, PLANT AND METHOD OF ENERGY EFFICIENCY FOR THE USE OF THERMAL SOLAR ENERGY - Google Patents

Description

DEVICE, SYSTEM AND METHOD WITH A HIGH LEVEL OF ENERGY EFFICIENCY FOR THE USE OF THERMAL ENERGY OF SOLAR ORIGIN

DESCRIPTION

Technical field of the invention

The present invention refers to a device for the accumulation and transfer of thermal energy of solar origin based on a bed of fluidizable particles directly irradiated by concentrated solar radiation.

The invention also relates to an energy production plant that includes this device and a related method.

Background

It is known to collect solar energy using heliostats that concentrate the radiation on reflecting mirrors. The latter, in turn, convey the radiation onto storage and heat exchange devices based on fluidized particle beds.

Systems for the production of thermal / electrical energy can be based on these devices for the accumulation and exchange of thermal energy of solar origin, which include one or more units depending on the thermal power to be obtained.

The prior art fluidized bed devices are made according to two main constructions.

On the basis of a first construction, described in WO2013 / 150347A1, the solar radiation is received on the walls of a metal cavity of the device. This cavity defines part of the envelope of the bed of particles and extends inside the latter. The fluidized particle bed removes the thermal energy deriving from solar radiation concentrated on them from the walls of the cavity.

In the presence of high incident radiative fluxes, the construction just described has the drawback of exposing the surface of the cavity to high temperatures and thermal gradients, with consequent criticalities in terms of thermo-mechanical resistance and durability deriving from the quality of the metal alloy used. To evenly distribute the thermal flows to which the cavity walls are exposed, the heliostat field can be organized in several sub-sections arranged around the device. However, this configuration requires a greater occupation of land for each solar generation unit than a single heliostat field positioned in the direction of greater irradiation.

In a second known construction, the aforementioned cavity is not provided and the bed of particles of the accumulation and exchange device receives concentrated solar radiation through a window of transparent material, typically quartz, obtained on the housing of the device itself.

However, a criticality of this second construction consists in the fact that direct contact of the transparent window with the fluidized solid must be avoided, and this in order to limit the onset, over time, of fouling phenomena, deposition of dust and / or opacification of the transparent surface that reduce the reception efficiency, determining, among other things, an increase in temperature and the establishment of thermal gradients on the window itself.

A further disadvantage related to the use of receiving means of the type just described is related to the difficulty of producing quartz windows of adequate size for the needs of an industrial size plant.

It should also be pointed out that known devices can present critical issues in terms of maintenance and the effectiveness and efficiency of the absorption and thermal transfer process.

As a result of the foregoing, the devices for the accumulation and transfer of thermal energy of solar origin known in the art produce, in some cases, a sum of inefficiencies such as not to allow a competitive industrial use.

Summary of the invention

The technical problem posed and solved by the present invention is therefore that of providing a device for accumulating and transferring thermal energy of solar origin which allows to overcome the drawbacks mentioned above with reference to the known art.

This problem is solved by a device according to claim 1.

The invention also provides a plant according to claim 28 and a method according to claim 31.

Preferred features of the present invention are the subject of the dependent claims.

The invention provides a device for receiving, storing and transferring thermal energy of solar origin based on a bed of fluidized particles. The latter is irradiated, i.e. struck, directly by concentrated solar radiation, without the interposition of receiving means such as cavities or transparent windows. In other words, the fluidized bed is directly in communication with the external environment by means of an irradiation opening obtained in an enclosure of the device, preferably at an upper part of the enclosure itself and even more preferably in a lateral position.

Therefore, the device of the invention, in use, does not provide for any transparent window, or other structure, interposed between the external environment / the incident solar radiation and the bed of particles.

Compared to prior art devices with indirect irradiation, the device of the invention allows a direct transfer of the incident radiative power to the fluidized solid without the interposition of walls or other barriers and a limitation of thermal losses through the irradiation opening. It follows that the maximum achievable temperature, limited exclusively by the properties of the fluidized solid, is higher than that tolerable in known indirect irradiation systems, with a significant increase in the thermal efficiency of the device.

The absence of windows, cavity walls or other barriers contributes to giving the device of the invention superior strength and durability.

Advantageously, the device is associated with an optical system, the latter comprising in particular primary heliostats and secondary reflecting means, for example mirrors. This optical system concentrates the solar radiation on the device, through the irradiation aperture, on an operating region of the bed of particles.

In a preferred configuration, the irradiation of the device occurs from above in an oblique direction with respect to the ground (or vertically) and is obtained by means of an optical system consisting of a field of heliostats positioned in the direction of greater irradiation, associated with a secondary reflector placed at a height, the focus of which corresponds to the aforementioned irradiation aperture.

The device of the invention typically comprises, or is associated with, heat exchange elements immersed in the granular bed. Such elements can include tube bundles or membrane walls, which are preferably traversed by an operating fluid at least in selected phases of the operation of the device.

In a preferred embodiment, the heat exchange elements inside the bed of particles are easily replaceable without the need to remove the particles of the bed. The replacement of the heat exchange elements may be necessary for maintenance or adaptation of the same to accommodate operating fluids of different nature (for example CO2 in supercritical state).

According to an aspect of the invention, an operative region of the bed of particles directly irradiated by the incident solar radiation can be fluidized according to a specific fluid dynamic regime, preferably obtained by means of a fluidization system, in particular a system for the supply and / or distribution of a gas fluidization, typically air. This system is preferably arranged at the base of the particle bed.

As mentioned above, the fluidization can affect an operating region of the bed directly exposed to the incident radiation, or the entire bed of particles or even selected portions of it.

The fluidization of the entire bed of particles allows to effectively homogenize the temperature of the bed itself, and this happens by continuously renewing the particles affected by the solar radiation concentrated in correspondence with the irradiation zone with other particles of the neighboring zones, with a continuous recirculation of the bed particles between the innermost zones and the directly irradiated zones.

Therefore, thanks to the fluid dynamic regime established by the fluidization system, the replacement of the bed particles at the irradiation opening, directly exposed to solar radiation, is allowed, and a transfer and distribution of thermal energy to the remaining part of the bed itself.

Advantageously, fluidization is associated with convective motions within the bed that allow the movement of the particles affected by concentrated solar radiation towards adjacent areas of the bed and attract new ones in correspondence with the irradiated area.

Advantageously, the means for the adduction and / or distribution of the fluidization gas that make up said fluidization system can be inspected from the outside of the device, without the need to remove the particles of the bed, and, if necessary, subjected to maintenance activities. / cleaning, working precisely from the outside. In this way, to inspect or maintain the device it is not always necessary to stop its operation, to wait for the particles of the bed to cool down (typically in the order of several tons of material) and to empty the device, particularly when the aforementioned adduction / distribution means are positioned at the base of the bed.

The fluidization air emerges from the bed of particles in an upper area inside a device casing and called freeboard.

In a preferred embodiment, a dedicated ventilation or suction system is provided connected to the internal environment of the device preferably in correspondence with the aforementioned freeboard. This ventilation system continuously sucks the emerging fluidization air, preferably causing a (slight) depression with respect to the external environment.

Downstream of a possible dedusting stage, this air can pass through a heat exchanger, typically external to the device, transferring its thermal content, for example to another operating fluid. This thermal content thus becomes usable for various purposes, such as for the water desalination process in a dedicated plant. More preferably, the fluidization air leaving the device can provide, by means of a special exchanger, the preheating of ambient air which is then introduced into the bed of particles by the aforementioned fluidization system. On the basis of a further variant, the ventilation system can determine a reintroduction of the air sucked by the freeboard directly into the particle bed, in particular at the base of it, for the purpose of fluidization of the bed itself.

Due to the thermo-fluid dynamic characteristics of the bed, the higher the speed of the particles, in particular as induced by the flow of fluidization air, and the greater the heat exchange coefficient that is determined within the bed itself. For this reason and to prevent dust and hot air from escaping from the device through the radiation opening, a particularly preferred configuration of the device provides for a synergy between the position of this opening, the configuration of the casing in the area delimiting the freeboard and / or the pressure in the freeboard itself.

According to a preferred configuration, the irradiation opening is positioned laterally on the device casing, typically at or near the top of it. In particular, the position of the opening is lateral with respect to a main fluidization direction of the bed of particles and / or to a longitudinal direction of extension thereof. Preferably, the part of the envelope that delimits the freeboard, which is typically an upper wall of the envelope itself, is configured as a sloping, or hood, with a margin or lower part in correspondence with the irradiation opening. Advantageously, in correspondence or proximity to a margin or upper part of said sloping configuration, a connection is arranged to the ventilation system that sucks the fluidization air emerging in the freeboard. In this way, the part of the casing involved works like a hood, favoring the convective motion of the hot fluidization air leaving the bed of particles towards the connection to the ventilation system, said air being preferably drawn by the depression induced by the action aspirant of that system. The hot air is then removed from the radiation opening.

In a preferred arrangement, the choice of the position of the irradiation aperture is such as to minimize the view factor of the portion of the bed directly irradiated by concentrated solar radiation. In particular, preferably no portion of the bed of particles is in direct correspondence to the irradiation opening according to the vertical or longitudinal direction, that is, it has a unitary view factor with respect to the opening itself. This configuration allows to minimize the heat losses due to re-radiation generated by the surface portion of the bed of particles and also reduces the risk of air and dust escaping.

According to a preferred embodiment, the ventilation system is configured to increase the suction speed as the temperature of the bed of particles increases. This automation allows to maintain a constant or in any case controlled depression in the freeboard area.

In any case, as mentioned above, the ventilation system can determine a pressure inside the device equal to or lower than that of the surrounding environment to reduce or eliminate the escape of hot air and any dust towards the environment outside the device.

In case of depression of the freeboard area with respect to the external environment, external air can enter the device through the radiation opening. This entry of external air can counteract the escape of fluidization air and dust through the opening itself.

According to another aspect of the invention, an auxiliary heat exchanger can be positioned in correspondence with the irradiation opening, completely or partially external to the envelope. This auxiliary exchanger can directly receive concentrated solar radiation, in particular in correspondence with an operating fluid that passes through it. The auxiliary exchanger can be independent of the exchangers immersed in the bed of particles and make the enthalpy content acquired by solar radiation immediately available for various purposes, for example to continuously feed a desalination plant associated with the device. In other applications, the auxiliary exchanger can be connected to the exchangers inside the bed of particles and provide for a preheating of the relative operating fluid.

The auxiliary exchanger can be housed inside an invitation means - for example of a truncated conical shape flared towards the outside - positioned in correspondence with the irradiation opening. This variant contributes to the preheating of the ambient air which can enter the device through the radiation opening.

The device of the invention can be part of a modular plant for the production of thermal energy from a solar source.

Other advantages, characteristics and methods of use of the present invention will become evident from the following detailed description of some embodiments, presented by way of non-limiting example.

Brief description of the figures

Reference will be made to the drawings of the attached figures, in which:

Figure 1 shows a schematic longitudinal sectional view of a solar thermal energy storage and exchange device according to a first preferred embodiment of the invention, associated with a so-called "beam down" optical system;

Figure 2 shows an enlarged schematic representation of the device of Figure 1, in association with some components of a heat exchange system;

Figure 3 shows another schematic enlarged representation of the device of Figure 1, also in association with some components of an energy production plant; And

Figure 4 shows a schematic longitudinal sectional view of a device for the accumulation and exchange of thermal energy of solar origin according to another more preferred embodiment of the invention, which can be combined with the system components and elements of the previous figures.

The linear and angular dimensions shown in the figures introduced above are intended as purely illustrative and are not necessarily represented in proportion.

Detailed description of preferred embodiments

Various embodiments and variants of the invention will be described below, and this with reference to the figures introduced above.

Similar components are denoted in the various figures with the same numerical reference.

In the following detailed description, further embodiments and variants with respect to embodiments and variants already dealt with in the same description will be illustrated limitedly to the differences with what has already been disclosed.

Furthermore, the characteristics of the different embodiments and variants described below are to be intended as combinable, where compatible.

With reference to Figure 1, a device for the accumulation and exchange of thermal energy of solar origin, or receiver, according to a first preferred embodiment of the invention is generally denoted with 1.

The device 1 of the present embodiment is intended to be inserted in an energy production plant 500, possibly including a plurality of devices such as the one considered here.

The system 500 may include an optical system configured to concentrate an incident solar radiation on the device or devices 1. Each device 1 can be associated with its own optical system. Advantageously, this optical system has a "beam down" configuration. In particular, the optical system can comprise a plurality of primary heliostats 501, or equivalent primary optical elements, arranged on the ground and suitable for collecting the solar radiation to deflect / concentrate it on one or more secondary reflection mirrors 502, or equivalent secondary optical elements. . The latter are arranged at a height, above the device or devices 1 arranged on the ground, and precisely convey the solar radiation onto the device or devices themselves. In Figure 1, a common focus of the primary optical elements is denoted with F1 and the focus of the secondary optical element represented is denoted with F2.

The primary heliostats 501 can be organized in subfields, for example arranged according to the cardinal points.

As shown in greater detail in Figure 2, the device 1 first of all comprises a containment casing 2, which defines an internal compartment 20, the latter suitable for hosting a bed of fluidizable particles 3 which will be discussed shortly. The envelope 2 can have polygonal geometry, for example cubic or parallelepiped, or cylindrical. In the present example, the casing 2 has an upper wall 21, a side skirt 23 and a lower wall or base 24.

With respect to the geometry of the device 1, we can define a longitudinal direction L, in the present example vertical, and a transversal direction T, orthogonal to the longitudinal direction L and in this example, therefore, horizontal.

The envelope 2 has an irradiation opening 10. The secondary reflectors 502 mentioned above concentrate the incident solar radiation just entering this opening 10, or at or near it (focus F2), and within the compartment 20.

The opening 10 places the internal compartment 20 in direct communication, and therefore the bed of particles 3 housed therein, with the external environment. In particular, the opening 10 is, in use, without closing means or screens such as transparent windows or other. In other words, the device 1 is configured to operate without closing means or shield. During non-operational periods, the opening can be closed using removable means to protect the system and to eliminate or reduce the dispersion of thermal energy to the external environment.

In the present example, the opening 10 is shown as arranged at the upper wall 21 of the envelope 2 and generally centered longitudinally with respect to it. This representation is in any case intended as purely illustrative and a particularly preferred arrangement of said opening 10 will be discussed later with reference to Figure 4.

The fluidizable particle bed 3 is of the granular type, ie formed by solid particles.

The type of granular material preferred for the bed of particles of the device 1 is of the type with thermal characteristics of high conductivity and diffusivity. An example of a preferred granular material is river sand, which, in addition to having suitable thermal characteristics, has a natural rounded shape of the particles which minimizes the phenomenon of mutual abrasion between them.

The bed 3 occupies the internal compartment 20 so as to leave, even in use, a vacant space 22, or freeboard, above its own free surface 35. In particular, the space 22 is delimited below by the free surface 35, above from the wall 21 of the casing 2 and laterally from the casing 23 of the casing itself.

The bed 3 defines a first region of the bed 30 whose free surface is arranged so as to be directly irradiated, ie hit, by the solar radiation that enters through the irradiation opening 10. This first region 30 will be called operative or irradiated. The remaining part of the bed, surrounding and adjacent the operative region 30, defines a heat accumulation region 31.

In general terms, in the example considered here, the operating region 30 is arranged longitudinally centered in the bed 3 and the accumulation region 31 is circumscribed to it and transversely adjacent to it.

Variants of construction may provide that the operational region, that is the one directly irradiated, occupies the entire extension of the bed 3.

The bed of particles 3 is set in motion by means of fluidization means 4 configured to supply and distribute a fluidization gas, in particular air, within the compartment 20. In the present embodiment, the means 4 comprise a plurality of adduction elements or inlet of fluidization air, arranged at the lower base 24 of the casing 2 or of the bed of particles 3. The path of the fluidization air within the bed of particles 3 is therefore from bottom to top, in particular vertical or substantially vertical. In more general terms, the introduction of the fluidization gas occurs according to the longitudinal direction L.

In the present example, these adduction elements are arranged - and therefore convey air - both at a base of the accumulation region 31 and at a base of the operative region 30. In Figure 2, an adduction element arranged at the operative region 30 is denoted by 40.

In the present example, uniform or substantially uniform fluidization of the particle bed 3, i.e. of its two regions 30 and 31, is provided.

The fluid dynamic regime of the bed 3 allows an effective heat exchange between the particles of its various parts, in particular between those of the operative region 30 and those of the accumulation region 31. This is favored by the fact that the particles of the bed, in particular those of the belonging to the two regions, they undergo a continuous exchange and recirculation. In use, the particles of the operative region 30, and in particular those arranged on or near the free surface 35, absorb thermal energy from the solar radiation and transfer it to the other particles of the bed, in particular those of the accumulation region 31.

As mentioned above, the heat exchange between the particles is favored by convective motions determined by the fluidization regime. These motions pour, in the upper part of the adjacent bed subregions, the particles of the subregion with a higher fluidization speed in the adjacent subregion with a lower fluidization speed and recall particles of the latter within the subregion at higher speed in the lower part of the adjacent subregions .

This mixing of the particles of sub-regions allows a transfer of mass and thermal energy in the entire volume of the bed operating region affected by the solar spot and maximizes the surface area of particles exposed to concentrated solar radiation.

Variants of embodiment can provide for a differentiated fluidization, possibly the fluidization of only one of the regions 30 and 31 and / or a temporally differentiated fluidization of the regions themselves. The fluidization of different bed regions or portions, or the selectable fluidization regimes for them, can differ in the speed, and possibly the flow rate, of the fluidization air flow entering the particle bed 3.

The fluidization elements can be uniformly arranged at the base of the bed of particles 3, as in the present example, or be positioned in a differentiated manner.

It is also possible to provide fluidization elements that are structurally similar to each other and possibly controlled differently, for example in terms of speed and / or flow rate.

The fluidization regime can also be of the boiling type and / or, in general, a regime which favors convective motions of particles in the bed 3 or in regions or portions thereof.

In some embodiments, the fluidization regime chosen for the entire bed or for a region or portion of it can also be of the so-called "spouted" type, for example jet, fountain or pulse. The spouted type fluidized bed generally has a hydrodynamic regime characterized by a central fluidization gas jet at the base of the same bed which, due to the strong difference in velocity between particles directly exposed to the jet and surrounding particles, establishes a motion dragged by of the bed column that insists on the casting itself and the facing (cylindrical) areas creating, precisely, a fountain effect in the central part fed by the solid dragged into the lateral parts of the casting.

Advantageously, the aforementioned elements for supplying the fluidization gas can be inspected from the outside of the device, i.e. without the need to remove the particles of the bed, and, if necessary, can be subjected to maintenance / cleaning activities, operating precisely from the external.

In the example considered here, the fluidization system comprises one or more ducts 45 for distributing the fluidization air, arranged horizontally at the base of the device 1 and preferably positioned to cross the device itself in correspondence with its shell or side wall 23. At the external side of the device 1 each duct 45 can be provided, for example, with a removable flange 46. In this way, if necessary, it is sufficient to remove the aforementioned flange 46 in order to inspect and access the internal part of the duct 45.

Within the bed 3, in particular within the accumulation region 31, heat exchange elements 5 are housed, in particular tube bundles. These tube bundles, in selected operating conditions, ie in certain conditions of use, can be traversed by an operating fluid, for example water in the liquid and / or vapor state.

In particular, in a heat exchange phase, i.e. in the phase of using the stored thermal energy, the operating fluid can be made to flow in the tube bundles 5 and receive heat from the particles of the accumulation region 31. On the contrary, during a phase of accumulation only, the tube bundles 5 can work dry, ie in the absence of operating fluid.

In a preferred application mode, the accumulation phase can be activated in the presence of sunshine. The heat exchange phase, i.e. the transfer of thermal energy to the operating fluid, can be activated even in the absence of the sun.

The fluidization of the bed of particles 3 or of a region or portion thereof can also occur only during the accumulation step.

The heat exchange elements 5 can be configured in such a way as to be easily replaceable without the need to remove the particles of the bed.

As shown in Figure 3, the operating fluid leaving the device 1 in the design temperature and pressure conditions can be made to expand in a turbine 510 coupled to a generator for the production of electrical energy or it can be used for other industrial purposes, for example for the production of hot water, in air conditioning systems or in desalination plants. In other words, the tube bundles 5 are connected to further components of the system 500, for example one or more turbines 510, condensers 511, heat exchangers 521, pumps 520 and so on, each known per se.

With reference again to Figures 2 and 3, the device 1 also comprises suction means 6 for the fluidization air which has finished its path within the bed of particles 3 and emerges from it at the freeboard 22. Said suction means 6 they are therefore configured to suck the air inside the casing 2 above the free surface 35 of the bed of particles 3. In the present example, the suction means 6 comprise elements 60 for exiting air from the vacant space 22 arranged in correspondence with a portion upper side skirt 23 of the casing 2.

Preferably, the suction means 6 are also configured to avoid an introduction, or a massive introduction, of fluidization air and / or of the particles dragged by it into the external environment through the opening 10.

Advantageously, the suction means 6 provide control means (not shown), preferably flow sensors, which, in synergy with further control means (not shown) associated with the fluidization means 4, determine a flow rate of air extracted from the device 1 equal to or greater than the flow rate of fluidization air introduced into the particle bed 3.

Preferably, the configuration of the suction means 6 is such as to cause a depression in the space 22. In this case, the suction means 6 cause the air from the environment to re-enter the device through the inlet opening 10. This air heats up in the passage through the inlet opening 10, enriching itself with a thermal content that is brought to the air extracted from the device 1.

Advantageously, the device 1 provides for a heat exchange between the fluidization air (heated) leaving the bed of particles 3 in correspondence with the free surface 35 of the latter and sucked by the means 6 and the fluidization air entering the bed of particles 3 by means of the fluidization means 4. In other words, a regeneration of the heat is provided, obtained by means of heat exchange. This is schematically represented in the figures by means of heat exchange components 512, components for dedusting 513 of the fluidization air, components for ventilation 514, for the intake of the fluidization air from the device and 515 for the introduction of ambient air to the fluidization system.

In a variant embodiment, the device 1 has a stilling chamber in correspondence with the free surface 35 of the bed of particles 3. This stilling chamber is intended as a zone of low or zero velocity for the particles of the bed and is defined, in the present example, from vacant space 22.

The stilling chamber 22 also helps to avoid a leakage, or a massive leakage, of air and / or particles through the opening 10.

In a variant embodiment, the device 1 can also comprise means for introducing a confinement gas, in particular air, in the form of a laminar flow. The latter is suitable for producing a (further) barrier to the escape of particles to the outside.

The means can be arranged above the free surface 35 of the bed of particles 3, in particular at the irradiation opening 10. Preferably, the arrangement is such that the laminar flow is emitted precisely at the opening 10, parallel to the direction traversal T of development of the latter, to form a sort of gas window for closing the latter.

In the present embodiment, the device 1 further comprises a shaped confinement structure 8, or invitation, arranged at the mouth of the irradiation opening 10. The confinement structure 8 can develop completely or mainly outside the device 1 , i.e. partially protrude or not within the vacant space 22.

The confinement structure 8 has a through opening, that is, it has a tubular construction, in such a way as to maintain direct communication between the interior and exterior of the envelope 2 by means of the irradiation opening 10.

In a variant embodiment, the confinement structure 8 defines a (further) stilling chamber and thus helps to avoid or reduce the leakage of air and / or particles to the outside.

In the present embodiment, the confinement structure 8 has a tapered conformation, in particular conical, with a decreasing section towards the inside of the envelope 2. This section of the confinement structure allows not to interfere with the direction of the solar radiation concentrated by the dedicated optical system.

Furthermore, in correspondence with the walls of the structure 8, air intake vents or equivalent suction elements can be obtained, which can be in communication with the environment of the freeboard 22 or be associated with a dedicated suction system. When in communication with the freeboard 22, these vents pour the sucked air into the space between the free surface 35 and the upper wall 21 of the casing 2 From here, this air flow is also sucked by the suction means 6 already introduced.

In a variant embodiment, the device 1 also comprises an external frame 80 which supports removable means in correspondence with the opening 10, to protect the system during non-operational periods thereof and such as to eliminate or reduce the dispersion of thermal energy towards the external environment.

According to a preferred embodiment, the device 1 comprises an auxiliary heat exchanger 9, arranged at the confinement structure 8 or, in general terms, at the irradiation opening 10. The auxiliary exchanger 9 is configured so as to be directly exposed to the incident solar radiation, so as to absorb heat, for example by means of its own vector fluid.

The auxiliary exchanger 9 can be independent of the heat exchange elements 5 immersed in the bed of particles or be connected to them.

Figure 4 refers to a particularly preferred embodiment of the device of the invention, also denoted here with 1. Although represented schematically, for this embodiment the same description described up to now applies, with the exception of the positioning of the opening of irradiation, here denoted by 10 ', which is arranged laterally on the casing 2. In particular, the opening 10' is obtained in correspondence with an upper part of the casing 2 and defined, in the present example, between a portion 230 of the lateral skirt 23 of the casing and an upper wall, in particular sloping, 210 of the casing 2 itself. In the present example, the portion 230 has an inclined trend with respect to the remaining part of the shell 23, and in particular with respect to the transverse T and longitudinal directions L, protruding towards the outside with respect to said remaining part of the shell. Preferably, the free surface 35 of the bed of particles 3 falls, in fluidization operating conditions, at or near the lower edge of the portion 230, in particular below it.

The sloping upper wall, or hood, 210, has a lower edge 211 which defines, together with the portion 230, the opening 10 ', and an upper edge 212 which is connected to an element or outlet 600 of the suction means or ventilation 6 already described above.

The focus F2 of the secondary optical element 502 mentioned with reference to Figure 1 falls at the mouth of the aperture 10 '.

As already highlighted above, the lateral position of the opening 10 ', the sloping configuration 210 of the casing 2 and / or the pressure regime in the freeboard 22 as obtained (also) by the suction means 6 are synergistic in improving the heat exchange. in the particle bed 3 and to prevent dust and hot air from escaping from the device 1.

Figure 4 also shows fluidization means 4 similar to those described above, but articulated with one or more central adduction elements 401 which can be independent from one or more side elements 402 and 403. These elements can also be inspected and / or maintained. from the outside, for example by means of one or more removable flanges 46 similar to those described above.

Figure 4 also highlights a multilayer construction for envelope 2.

The device of the invention is modular in nature, ie it is well suited to be connected to one or more similar devices in series or in parallel with respect to the heat exchange.

Furthermore, the types of devices according to the different embodiments and variants described can be favorably associated for greater flexibility of production and / or operation of the industrial plant.

The management of the energy production plant shown by way of example in Figure 3 is preferably carried out by means of a control software that optimizes its operation based on user requests and / or weather conditions, with the result of obtaining an operation of the total flexibility system.

Still in a preferred configuration, the system based on one or more of the devices of the invention can be advantageously associated with a photovoltaic system which provides the daytime production of electricity and which compensates for the consumption of the auxiliaries of the system. In this configuration, the storage and transfer devices can be managed in the solar thermal energy storage regime during the sunny hours and in the thermal energy transfer regime, transferring it to the operating fluid that crosses the internal exchangers in the bed of particles, for the production of electricity, from dusk onwards.

Furthermore, in the same configuration, the plant can be associated with a desalination plant or other system for exploiting thermal energy of solar origin. In this case, the devices can be managed in a mixed regime: both for storage, for the nocturnal production of electricity, and for simultaneous transfer, dedicating the related transfer of thermal energy to the continuous operation of the plant, for example for desalination.

The device of the invention can be integrated with plants powered by other renewable energy sources (for example photovoltaic, wind, geothermal) or non-renewable to guarantee the continuity of energy production in order to reduce or eliminate the production of energy generated by non-renewable sources. .

In all the embodiments and variants described, the transport of energy from the concentrated radiative beam to the fluidized bed is entrusted to the granular material which becomes the primary vector of thermal energy, unlike traditional membrane or transparent window receiving means which, interposing between the concentrated energy and the correlated thermal vector, they determine a physical separation.

The invention also provides a method of accumulation and exchange of thermal energy of solar origin, based on the functions already described above in relation to the device and system of the invention.

The present invention has been described up to now with reference to preferred embodiments. It is to be understood that there may be other embodiments that pertain to the same inventive core, as defined by the scope of the claims set out below.

Claims (40)

CLAIMS 1. Device (1) for the accumulation and exchange of thermal energy of solar origin, which device (1) is configured to receive concentrated solar radiation by means of an optical system, which device (1) includes: a casing (2) which defines an internal compartment (20) and has an irradiation opening (10; 10 ') configured to allow the entry of concentrated solar radiation, which opening (10; 10') places said internal compartment (20) with the external environment being devoid, in use, of closing means or screen; a bed (3) of fluidizable solid particles, received within said internal compartment (20) of said envelope (2), which bed (3) has an operative region (30) directly exposed, in use, to the concentrated solar radiation which enters through said opening (10; 10 '), in such a way that the particles of said operative region (30) absorb thermal energy from the solar radiation; And means (4) for fluidizing said bed of particles (3), configured to feed a fluidization gas into said compartment (20) at least in correspondence with said operating region (30). Device (1) according to claim 1, wherein said opening (10 ') is arranged in a lateral or decentralized position on said casing (2), in particular laterally with respect to said operative region (30), preferably in correspondence of a upper wall (210) and / or a side skirt (230) of said casing (2). Device (1) according to claim 1 or 2, wherein said irradiation aperture (10 ') is defined in correspondence with an inclined portion (230), in particular protruding towards the outside, of a side skirt (23) of said casing (2). Device (1) according to any one of the preceding claims, in which said irradiation aperture (10 ') is defined in correspondence with a sloping inclined upper part (210) of said casing (2), and in which preferably said part top (210) defines, with respect to the free surface (35) of the bed of particles (3), a substantially suction hood configuration. Device (1) according to any one of the preceding claims, wherein the arrangement is such that the view factor of said irradiation aperture (10 ') with respect to the free surface (35) of said operative region (30) is lower than 1. Device (1) according to any one of the preceding claims, wherein said fluidization means (4) are configured to supply the fluidization gas in a prevalent longitudinal direction (L) to the particle bed (3), in particular a direction substantially vertical. Device (1) according to any one of the preceding claims, wherein said fluidization means (4) comprise one or more fluidization gas supply elements (40; 401-403), preferably arranged at a lower base ( 24) of said bed of particles (3) or of said envelope (2). Device (1) according to any one of the preceding claims, wherein said fluidization means (4) comprise one or more fluidization gas supply elements (40; 401-403) accessible or inspectable from the outside of the device itself ( 1), i.e. without the need to remove the particle bed (3). Device (1) according to any one of the preceding claims, wherein said fluidization means (4) are configured to determine, in use, at least two different fluidization rates within said bed of particles (3), in particular within said region operational (30). Device (1) according to any one of the preceding claims, wherein said fluidization means (4) are configured to determine, in use, a convective circulatory motion of particles within said bed of particles (3), in particular within said region operational (30). Device (1) according to any one of the preceding claims, wherein said fluidization means (4) are configured to determine, in use, a spouted type fluidization regime in said operating region (30). 12. Device (1) according to any one of the preceding claims, in which said operating region (30) substantially occupies the entire bed of particles (3). Device (1) according to any one of claims 1 to 11, wherein said bed (3) has a heat accumulation region (31) adjacent to said operative region (30), and preferably circumscribed thereto. Device (1) according to the preceding claim, in which the overall configuration is such that, in use, the particles of said operative region (30) absorb thermal energy from the solar radiation and transfer it to the particles of said accumulation region (31 ). Device (1) according to any one of the preceding claims, wherein said casing (2) has an inclined or sloping surface (210) arranged above the free surface (35) of said bed of particles (3) and having a lower margin (211) at or near said irradiation aperture (10 '), the configuration preferably being such that said inclined surface (210) is suitable for favoring a suction effect of the fluidization gas emerging from the bed of particles ( 3). Device (1) according to any one of the preceding claims, comprising means (6) for aspirating fluidization gas, arranged inside said casing (2) above the free surface (35) of said bed of particles (3). Device (1) according to claims 15 and 16, wherein said suction means (6) comprise a suction inlet (600) arranged at or near an upper edge (212) of said inclined surface (210). Device (1) according to claim 16 or 17, comprising means for transferring the fluidization gas sucked by said suction means (6) at the inlet to said fluidization means (4). 19. Device (1) according to claim 16 or 17, comprising heat exchange means between the fluidization gas entering said casing (2) by means of said fluidization means (4) and the fluidization gas leaving said casing ( 2) by means of said suction means (6). Device (1) according to any one of claims 16 to 19, wherein said suction means (6) are configured to extract from the device (1) a flow rate of fluidization gas equal to or greater than a flow rate of fluidization gas introduced into said bed of particles (3) by said fluidization means (4). Device (1) according to any one of claims 16 to 20, in which said suction means (6) are configured to cause a depression in correspondence with a vacant space (22) interposed between the free surface (35) of the bed of particles (3) and an upper part (21; 210) of said envelope (2). Device (1) according to any one of the preceding claims, comprising a shaped confinement structure (8), configured to contain the particles of said bed (3) within said enclosure (2), which confinement structure (8) is arranged in correspondence with said irradiation opening (10) and preferably at least partially protruding outwards with respect to the latter. 23. Device (1) according to the previous claim, in which said confinement structure (8) has a tapered, preferably conical shape, with a decreasing section towards the inside of said casing (2). Device (1) according to any one of the preceding claims, comprising auxiliary heat exchange means (9) positioned in such a way as to be directly irradiated, in use, by solar radiation and preferably arranged at or near said irradiation aperture (10). Device (1) according to the preceding claim and according to claim 22 or 23, in which said auxiliary heat exchange means (9) are arranged in correspondence with an internal or external wall of said confinement structure (8). Device (1) according to any one of the preceding claims, comprising heat exchange elements (5) arranged within said bed of particles (3) and traversed, in use, by an operating fluid. Device (1) according to claim 24 or 25 and according to claim 26, wherein said auxiliary heat exchange means (9) are connected to said heat exchange elements (5). 28. Thermal energy production plant (500), comprising: at least one device (1) for accumulating and exchanging thermal energy of solar origin according to any one of the preceding claims; and an optical system configured to concentrate an incident solar radiation at said irradiation aperture (10; 10 ') of said at least one device (1), in which said optical system preferably has a "beam down" configuration comprising one or more elements primary optical elements (501) arranged on the ground and one or more secondary optical reflection elements (502) arranged at height. System (500) according to the preceding claim, further comprising a photovoltaic system. Plant (500) according to claim 28 or 29, comprising a desalination system. 31. Method of accumulation and exchange of thermal energy of solar origin, which method provides for the irradiation of a bed (3) of fluidized solid particles with a concentrated solar radiation by means of an optical system, in which said bed of particles (3) is housed in a casing (2) equipped with an irradiation aperture (10; 10 ') configured to allow the entry of concentrated solar radiation, which opening (10; 10') places the bed of particles (3) in direct communication with the external environment as it has no closing means or screen , wherein said bed of particles (3) has an operative region (30) directly exposed to the concentrated solar radiation which enters through said opening (10; 10 '), so that the particles of said operative region (30) absorb thermal energy from solar radiation. Method according to claim 31, wherein a fluidization gas is fed into said bed of particles in a prevalent longitudinal direction (L) to the particle bed (3) itself, in particular a substantially vertical direction. 33. A method according to claim 31 or 32, wherein said fluidization gas is supplied at a lower base (24) of said bed of particles (3) or of said shell (2). 34. Method according to any one of claims 31 to 33, which provides at least two different fluidization rates within said bed of particles (3), in particular within said operating region (30). Method according to any one of claims 31 to 34, which provides for a convective circulatory motion of particles within said bed of particles (3), in particular within said operating region (30). Method according to any one of claims 31 to 35, wherein the particles of said operating region (30) absorb thermal energy from the solar radiation and transfer it to the particles of an adjacent storage region (31). Method according to any one of claims 31 to 36, which provides for a suction of fluidization gas above the free surface (35) of said bed of particles (3), preferably in correspondence with a lateral suction inlet (600). 38. Method according to the preceding claim, which provides for a heat exchange between the fluidization gas entering said bed of particles (3) and the fluidization gas aspirated above the free surface (35) of said bed of particles (3). 39. Method according to claim 37 or 38, wherein said suction causes a depression at a vacant space (22) interposed between the free surface (35) of the bed of particles (3) and an upper part (21; 210) of said casing (2). Method according to any one of claims 31 to 39, which uses a device (1) or an implant according to any one of claims 1 to 30.