System for storing thermal energy from electrical energy for steam generation

Abstract

The invention relates to the system for storing thermal energy from electrical energy for process steam generation, which comprises a tank (1) containing a volume of molten salts (2), an upper closure (21) of the tank (1) with openings (22) with flanged connections (5), and a plurality of functional elements (6) selected from at least one heat-dissipating element (7) and / or at least one steam generator (8) and which comprise a salt-circulating system for promoting heat transfer that includes a housing (30), a pumping element (12) designed to suction the molten salts (2) from inside the tank (1) and pump them to an inlet section (31) of the housing (30), and a set of partitions (33), arranged alternately inside the housing (30) perpendicular to the longitudinal direction of the housing (30).

Description

[0001] THERMAL ENERGY STORAGE FACILITY FROM ELECTRICAL ENERGY FOR STEAM GENERATION

[0002] DESCRIPTION

[0003] OBJECT OF THE INVENTION

[0004] The invention relates, as expressed in the title of this specification, to a thermal energy storage facility charged with renewable electrical energy for the generation of process steam. The ultimate goal of the invention is the decarbonization of countless industrial processes that use fossil fuels for the generation of low- and medium-pressure steam, which contribute significantly to the increase in atmospheric concentrations of CO2, a gas considered the main precursor to the greenhouse effect.

[0005] SCOPE

[0006] The field of application of the present invention is the electrification of thermal consumption in industry, through the generation of process steam from renewable energies.

[0007] BACKGROUND OF THE INVENTION

[0008] The expansion of renewable energy sources in recent decades has helped prevent the emission of huge amounts of CO2 into the atmosphere in the electricity generation sector. However, the majority of emissions of this pollutant come from heat generation processes in industry, which have continued to increase in demand, causing the net result of global greenhouse gas emissions to continue to grow in recent years.

[0009] The undispatchable nature of these forms of renewable energy means that electricity generation cannot be adapted to specific demand. This has led to a rapid increase in installed capacity. Therefore, although renewable electricity generation can sometimes exceed seasonal demand in certain markets under favorable weather conditions (abundant solar radiation and continuous moderate wind), the necessary stability of electricity grids imposes restrictions in the form of power limits on photovoltaic and wind energy. Thus, renewable energies that should normally contribute to reducing CO2 emissions are limited in their potential by low demand at certain times of the day.

[0010] Despite the above, continued growth in renewable energy is expected, and therefore in situations where surplus energy from this source is produced.

[0011] In this context of continuously increasing heat requirements and surplus situations in renewable electricity generation, the need for facilities capable of consuming this surplus electricity and storing it in the form of heat for the continuous generation of steam for industrial processes is evident.

[0012] This would shift the use of fossil fuels from steam generation, effectively decarbonizing one of the sectors with the greatest impact on global warming.

[0013] Thermal energy storage facilities have traditionally been developed in the field of Concentrating Solar Power (CSP) plants. These heat storage facilities consist of two molten salt tanks called a cold tank and a hot tank. One of them, the hot tank, stores the salts heated directly or indirectly by concentrated solar radiation. The other tank, the cold tank, receives and stores the salts that have released the previously accumulated sensible heat. The main advantage of this type of storage is that it can manage the stored thermal energy to continue producing steam during periods without radiation. Finally, the generated steam is turbined for electricity production.

[0014] These storage facilities are based on highly mature technology and equipment, making them excellent candidates for the aforementioned decarbonization goals. In recent years, solutions have been proposed aimed at reducing the complexity and space requirements of these facilities. One example is the use of a single thermocline tank in which the salts are stratified, generating two zones: a cold one at the bottom of the tank and a hot one at the top. These facilities represent savings in salt inventory and equipment investment, as well as a significant reduction in the footprint for their implementation. However, their industrial development has been relegated to a few applications, most of them experimental.Furthermore, and most importantly, its use is directly linked to concentrated solar installations, requiring salt transfer from the tank to external equipment for both energy loading and unloading. All these transfer operations involve a considerable investment in equipment and also increase the risk of salt freezing due to malfunction or failure of the heating and insulation systems.

[0015] In this regard, efforts have been made to make these facilities more compact, such as the installation described in publication CN203131781 U. It describes a salt storage tank with an integrated steam generation unit, but intrinsically associated with a solar field and a concentration tower for energy loading, which is carried out in equipment separate from the tank. This entails the necessary movement of salts from the tank to the tower, entailing the cost of pumping and the risk of the salt freezing.

[0016] DESCRIPTION OF THE INVENTION

[0017] The present invention consists of a thermal storage facility using renewable electrical energy for use in steam generation, either simultaneously during the charging process itself or in a deferred manner during times when electricity is unavailable.

[0018] The facility's unique feature lies in its maximum degree of compactness. In this sense, the facility integrates, within a single storage tank, heating via electrical energy (storage charging), steam generation (storage discharging), and molten salt circulation. The proposed concept offers the following advantages over a conventional installation of this nature:

[0019] Significant reduction in investment costs, due to savings in piping, pumping equipment, valves, instruments, heating elements (electrical tracing), insulation, support, etc.

[0020] Improved operability and reliability.

[0021] Reduced maintenance.

[0022] Reduction in space requirements for implementation in existing facilities, due to the reduced footprint required.

[0023] The invention relates to a thermal energy storage facility using electrical energy for generating process steam, which may comprise: a cylindrical atmospheric tank containing a volume of salts inside; an upper enclosure of the tank by means of an outer enclosure plate not supported on the tank; a sealing joint between the outer enclosure plate and the cylindrical atmospheric tank; a plurality of functional elements for generating heat and steam, grouped around the axis of the tank, each of which is constituted by: a heat dissipating element of longitudinal configuration that runs from the top of the tank to a certain depth;a steam generator consisting of a steel conduit that has two sections connected to each other, whose longitudinal axes are parallel to the axis of the heat dissipating element: a first longitudinal section through which the water runs downwards to a certain depth and a second section of ascending helical shape that encompasses in its interior region both the previous vertical section and the electrical resistance; a connection flange joined to the outer enclosure plate, which provides support for both the heat dissipator and the steam generator; a drive element, consisting of: a rotating shaft that passes through the outer enclosure plate of the tank through a connection flange and runs to the interior of the tank; and a rotor located at one end of the rotating shaft, which produces, depending on its design and direction of rotation, a downward movement of the molten salts.

[0024] In the described embodiment, the heat dissipating element is preferably an electrical resistor in the form of an elongated bar.

[0025] In a particular embodiment, the invention describes a thermal energy storage facility from electrical energy for the generation of process steam, comprising: an atmospheric tank, which in a preferred embodiment is cylindrical, containing a volume of salts inside; an upper enclosure of the tank and a support plate (which is preferably a plate with a flat surface) with openings provided with flanged connections for the installation of functional elements; a plurality of functional elements, installed in the upper enclosure of the tank, and distributed homogeneously inside the tank, remaining submerged in the volume of molten salts, and these functional elements can be of two types: heat dissipating elements; and steam generating elements.

[0026] The functional elements (both heat dissipating elements and steam generators) preferably have a longitudinal configuration and run from the top of the tank to a certain depth.

[0027] The functional elements have the following characteristics: they are supported by the support plate, i.e., they are supported by structures independent of the tank's upper enclosure; the flanged connections to the support plate are insulated using expansion joints, preferably textile or metal, thereby ensuring the tightness of the tank's interior atmosphere, preventing the entry of ambient air through the openings in the support plate where the functional elements are inserted, while also preventing the transmission of their weight to the tank.

[0028] Furthermore, in one embodiment, the functional elements comprise a salt circulation system which in turn comprises: a metal casing surrounding the corresponding functional element (the heat dissipating element or the steam generator) and said casing has one end arranged on the outside of the tank, integral with the support plate, and the casing comprises a salt inlet section, close to the surface of the volume of molten salts in the tank, and an outlet section at the bottom of the casing; a salt driving element (which may be, for example, a pump), the longitudinal axis of which is parallel to the axis of the functional element, where the driving element is configured to suck in the molten salts and drive them through the inlet section of the metal casing, promoting a speed of salts around the functional element for adequate heat exchange;a set of partitions, the partitions being placed alternately inside the metal enclosure, in such a way that they produce a flow of salts in a transverse direction, from right to left and from left to right, along the length of the functional element.;

[0029] Steam generator-type functional elements have an inert gas inlet, for example nitrogen, in the part of the metal casing located on the outside of the tank. The inert gas introduced generates a controlled pressure inside the steam generator casing, causing the molten salt column inside to move. The pressure exerted by the inert gas must remain below a threshold value, beyond which the surface area of ​​the molten salt column displaced inside the casing would reach the salt outlet section and / or the suction path of the salt drive element.

[0030] This system eliminates contact between the molten salts and a portion of the steam generator, thereby reducing heat transfer to the water-steam circuit. This prevents sudden evaporation of the water entering the steam generator during startup. It can also be used to regulate steam production.

[0031] By releasing the inert gas pressure, the level of the molten salts in the shell is equalized to the level of the tank (i.e., the height to which the molten salts rise in the shell is equalized to the height at which the surface of the salt volume in the tank is located).

[0032] In a possible embodiment, the installation may also comprise a prismatic or cylindrical steel casing that is concentric with the axis of the tank and runs vertically from the lower part of the tank to its upper part, without reaching the level of molten salts or the bottom of the tank, housing inside it all the functional units and the drive element.

[0033] Furthermore, the sleeve may include, inside, arranged perpendicular to the longitudinal axis, a group of flat, interior metal plates arranged equidistant from each other, alternating vertically and of two types. On the one hand, there is a first plate, the outer perimeter of which closes with the inner surface of the sleeve and has a hole in its central area through which molten salts may flow. On the other hand, there is a second plate, the outer perimeter of which encloses a section smaller than that of the sleeve, such that a free section would be established between said plate and the inner surface of the sleeve through which molten salts may flow.

[0034] DESCRIPTION OF THE DRAWINGS

[0035] To complement the description, and in order to facilitate the understanding of the characteristics of the invention, a series of figures are attached for illustrative and non-limiting purposes:

[0036] Figure 1 shows a general perspective and sectional view of the electrical energy storage installation and composed of a plurality of functional units (functional elements) distributed around the axis of the salt tank.

[0037] Figure 2 represents several views of the functional units, both individually and as a whole.

[0038] Figure 3 shows several views of the cylindrical sleeve and the main elements with which it is assembled.

[0039] Figure 4 shows a side and sectional view of the drive element. Figure 5 shows a sectional view of the installation in an embodiment comprising a functional element of the steam generator type.

[0040] Figure 6 shows a sectional view of the installation in an embodiment comprising a functional element of the heat sink type.

[0041] Figure 7 illustrates the displacement of salts within a functional element of the steam generator type by the action of the inert gas pressure system.

[0042] Figure 8 shows a sectional perspective view of the installation of the invention in which the tank, the volume of salts and a plurality of functional elements can be seen.

[0043] Numerical references:

[0044] 1: tank; 2: molten salt; 3: outer enclosure plate; 4: supporting structure; 5: connection; 6: functional element; 7: heat sink; 8: heat generator; 9: first section; 10: second section; 11: connection flange; 12: drive element; 13: rotating shaft; 14: connection flange; 15: rotor; 16: sleeve; 17: upper section; 18: lower section; 19: first plate; 20: second plate; 21: upper enclosure; 22: opening; 23: support plate; 24: longitudinal conductor; 25: steel duct; 26: collector; 27: vertical pipe; 28: steam collector; 29: steam outlet duct; 30: shell; 31: inlet section; 32: outlet section; 33: Partition assembly; 34: Inert gas inlet; 35: Pressure vessel; 36: Pressure regulating valve; 37: Relief valve

[0045] DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

[0046] The thermal energy storage facility of the invention consists of a tank

[0047] (1) cylindrical atmospheric steel, containing a volume of molten salts inside

[0048] (2) with sufficient circulation to achieve a homogeneous temperature (isoclinic tank). The tank (1) is enclosed at its top by means of an outer enclosure plate (3) resting on a support structure (4) independent of the tank (1) itself. The tightness between the tank (1) and the outer enclosure plate (3) is achieved on the periphery by means of a connection (5), which in an embodiment such as that shown in Figure 1 is a bellows-type joint (5), whether textile or metallic. The volume of the tank (1) and of the salts (2) is calculated based both on the desired storage capacity and on the requirements of the required conditions of the steam to be produced. Distributed in the tank (1), there are a plurality of functional units (6), each of which integrates:

[0049] - a heat dissipating element (7) of elongated configuration, preferably an electrical resistance in the form of an elongated bar, which runs from the top of the tank (1) to a certain depth;

[0050] - a steam generator (8) consisting of a steel conduit that has two sections connected to each other, whose longitudinal axes are parallel to the axis of the heat dissipating element (7): a first longitudinal section (9) through which the water flows downwards to a certain depth and a second section (10) of ascending helical shape, which encompasses in its interior region, surrounding it, both the first longitudinal section (9) and the heat dissipating element (7);

[0051] - a connection flange (11), connected to the outer enclosure plate (3), which allows the removal of the assembly consisting of the heat dissipating element (7) and the steam generator (8) for maintenance. Additionally, it serves as a support for the water inlet and steam outlet connections.

[0052] In a particular embodiment of the invention, the tank (1) has an upper end with an upper enclosure (21) which is preferably a flat surface. Said upper enclosure (21) comprises a plurality of openings (22) provided with connections (5), which in the embodiments shown in Figures 5 to 8 are flanged connections (5) for the installation of the functional elements (6). The openings (22) are closed by means of support plates (23) (preferably metallic) on which functional elements (6) are installed. The support plates (23) (which are preferably flat) are supported on a structure independent of the tank (1) such that their weight, together with that of the functional elements (6) that are attached to the support plates (23), is not transmitted to the tank (1).

[0053] The volume of the tank (1) and molten salts (2) is calculated based on both the desired storage capacity and the requirements of the required conditions of the steam to be produced. Distributed in the tank (1), the functional elements (6) are arranged, attached to the support plate (23) which are selected from: heat dissipating elements (7) and steam generators (8).

[0054] In one embodiment of the invention, the heat dissipating elements (7) are electrical resistors comprising a plurality of longitudinal conductors (24) that run from an upper part of the tank (1) to a certain depth thereof.

[0055] For its part, in one embodiment of the invention, the steam generators (8) comprise a steel conduit (25) through which liquid water circulates downwards to a collector (26), and from said collector (26) a plurality of vertical tubes (27) extend through which a two-phase water-steam mixture ascends to a steam collector (28), located in an upper part of the steam generator (8), from where a steam outlet conduit (29) comes out.

[0056] To promote heat transfer, the functional elements (6) have a salt circulation system comprising: an enclosure (30) (preferably a metal enclosure) surrounding the functional element (6) (the heat dissipating element (7) or the steam generator (8)) where said enclosure (30) has an end arranged on the outside of the tank (1), which in one embodiment is integral with the support plate (23), and the enclosure (30) has a salt inlet section (31), close to the surface of the molten salt volume (2) in the tank (1), and an outlet section (32) at the bottom of the enclosure (30);a salt driving element (12) (which in one example is a pump) with a longitudinal axis that is parallel to the longitudinal axis of the functional element (6) and where the salt driving element (12) is configured to aspirate the molten salt and propel it through the inlet section (31) of the casing (30), favoring a speed of salts around the functional element (6) for adequate heat exchange; a set of partitions (33), placed alternately inside the casing (30), in a direction transverse to the longitudinal direction of said casing (30), such that they produce a flow of salts in a transverse direction, from right to left and from left to right, along the length of the functional element.;

[0057] The number of functional elements (6) distributed in the tank (1), as well as their length (of the heat dissipating elements (7) and the steam generators (8)), depend on the maximum design heating power and the amount of steam to be generated.

[0058] Thus, in a preferred embodiment, the installation comprises an atmospheric tank (1), which in a preferred embodiment is cylindrical, and which contains inside a volume of molten salts (2) and which has an upper enclosure (21) of the tank (1) comprising openings (22) with flanged connections (5) that receive a plurality of functional elements (6) (installed in the openings (22) with flanged connections (5). These functional elements (6) are selected from at least one heat dissipating element (7) and / or at least one steam generator (8), and are partially submerged in the volume of molten salts (2).

[0059] Each functional element (6) comprises a salt circulation system to improve heat transfer and said salt circulation system comprises a casing (30), a drive element (12) and a set of partitions (33). The casing (30) surrounds the heat dissipating element (7) or the steam generator (8), comprises an end arranged outside the tank (1), and comprises a salt inlet section (31) and an outlet section (32). The drive element (12) is configured to aspirate the molten salts from the interior of the tank (1) and propel them to the inlet section (31) of the casing (30). The set of partitions (33) comprises a plurality of partitions arranged alternately inside the casing (30), in a direction transverse to the longitudinal direction of the casing (30).

[0060] Preferably, the functional elements (6) are distributed homogeneously in the tank (1) with respect to a central longitudinal axis of the tank (1). Also preferably, the functional elements (6) have a longitudinal configuration and extend from the outside of the tank (1) to a certain depth inside the tank (1), at which they are submerged in the volume of molten salts (2). The drive element (12) (salt drive element (12)) has, in a possible embodiment, a longitudinal axis parallel to longitudinal axes of the functional elements (6).

[0061] When the functional elements (6) are heat dissipating elements (7), they can be electrical resistors comprising a plurality of longitudinal conductors (24) that extend longitudinally from the outside of the tank (1) to a certain depth inside the tank (1) in which they are submerged in the molten salts (2).

[0062] Likewise, when the functional elements (6) are steam generators (8), they may comprise a steel conduit (25) with a water inlet, through which liquid water flows downwards to a collector (26). From said collector (26) extend a plurality of vertical tubes (27), through which a two-phase water-steam mixture flows upwards to a steam collector (28). This steam collector (28) is arranged in an upper section of the steam generator (8), where there is a steam outlet conduit (29).

[0063] Furthermore, in one embodiment, the steam generators (8) comprise an inert gas inlet (34) in an upper section of the steam generator (8) that is arranged outside the tank (1). In another embodiment, the installation comprises a pressure tank (35) connected to each steam generator (8) by its upper section that is arranged outside the tank (1), and pressure regulating valves (36) are arranged in each connection. Additionally, the installation may comprise a relief valve (37) in the connections between the pressure tank (35) and the steam generators (8).

[0064] In one embodiment of the invention, an upper section of the shell (30), in which the end of the shell (30) that is arranged outside the tank (1) is located, is integral with the support plate (23). In a possible embodiment of the invention, the salt inlet section (31) and the salt outlet section (32) are arranged in a section of the shell (30) that is housed in the tank (1). In another possible embodiment, in addition, at least the salt outlet section (32) is submerged in the volume of molten salts (2) and the inlet section (31) is arranged at a height greater than that of the salt outlet (32).

[0065] In an exemplary embodiment, the functional elements of the steam generator type (8) have a heat transfer regulation system consisting of an inert gas inlet (34), for example nitrogen, in the external part of the metal casing (30). The inert gas comes from a pressure tank source (35) from which lines are derived to each steam generator (8). A pressure regulating valve (36) is installed in each line that adjusts the pressure on the casing (30) of the functional unit, generating a displacement of the salt column inside it. The pressure exerted by the inert gas is such that the surface of the salt column displaced inside the casing (30) does not reach the salt outlet section or the suction path of the drive element (12).

[0066] In a possible embodiment of the invention, inside the tank (1), the functional units (6) are distributed grouped around the central axis thereof (assuming a cylindrical tank (1). In addition, the axis of the tank (1) is occupied by a drive element (12) provided with a rotating shaft (13) that passes through the outer enclosure plate (3) of the tank (1) through a connection flange (14) and runs to the interior. At its end, the rotating shaft (13) drives a rotor (15), which produces, depending on its design and direction of rotation, a downward movement of the molten salts (2). The drive element (12) can be removed as a whole by disassembling its connection flange (14), which allows for its eventual maintenance or inspection. To this end, the functional units (6) that surround the drive element (12) are located in such a way as to leave sufficient space to allow the passage of the rotor (15).

[0067] The set of functional units (6) and the drive element (12) are submerged, arranged in the interior volume of the tank (1) and delimited by a prismatic or cylindrical steel jacket (16). Said jacket (16) is concentric with the axis of the tank (1) and runs vertically from the lower area of ​​the latter to its upper area, without reaching the salt level (2) or the bottom of the tank (1). The jacket (16) has two passage sections for molten salts (2) in its circulation, the upper one (17) being the inlet section for the salts (2) and the lower one (18) being the outlet section. The function of this jacket (16) is to confine the forced flow of salts (2) driven by the rotor (15) in the area of ​​the steam generators (8) and the heat dissipating elements (7), so that appropriate speeds (magnitude and direction) can be obtained to achieve the required heat transfer.The length of the rotating shaft (13) of the drive element (12) is such that the rotor (15) is located in the upper section of the cylindrical sleeve (16). The sleeve (16) has a bell shape in its lower section (18), its perimeter approximating the lower perimeter area of ​​the tank (1). In this way, the circulation of the molten salts (2) is encouraged in this area, where there is a greater risk of stagnation and, therefore, freezing.

[0068] Inside the sleeve (16), and arranged perpendicularly to its longitudinal axis, there are a group of flat interior metal plates arranged equidistant from each other, which are of two types: a first plate (19), whose outer perimeter closes with the inner surface of the sleeve (16) and has an orifice in its central area through which there may be a flow of molten salts (2); and a second plate (20), whose outer perimeter encloses a section lower than that of the sleeve (16), leaving a free section through which a flow of molten salts (2) occurs.

[0069] The inner plates (19, 20) are alternated and have the holes machined for the passage of the functional units (6), leaving the minimum possible space for the extraction of said elements.

[0070] The function of the inner plates (19, 20) is to force a cross flow inside the jacket (16) around the functional units (6), greatly favoring the heat transfer mechanisms during the energy charging and discharging processes.

[0071] The pressure in the casing (30) can be released by a relief valve (37), which can be a three-way valve, so that the level of the molten salts (2) in the casing (30) is equal to the level of the tank.

[0072] Therefore, the invention comprises an embodiment in which the installation for storing thermal energy from electrical energy for the generation of process steam, comprising:

[0073] - a cylindrical atmospheric tank (1) containing a volume of molten salts (2);

[0074] - an upper enclosure of the tank (1) by means of an outer enclosure plate (3);

[0075] - a support structure (4) where the outer enclosure plate (3) rests;

[0076] - a sealing gasket (5) between the outer enclosure plate (3) and the cylindrical atmospheric tank (1);

[0077] - a plurality of functional elements (6) for generating heat and steam, grouped around the axis of the tank (1), each of which consists of:

[0078] - a heat dissipating element (7) of longitudinal configuration that runs from the top of the tank (1) to a certain depth;

[0079] - a steam generator (8) consisting of a steel conduit that has two sections connected to each other, whose longitudinal axes are parallel to the axis of the heat dissipating element (7): a first longitudinal section (9) through which the water flows downwards to a certain depth and a second section (10) of ascending helical shape that includes in its interior region both the first longitudinal section (9) and the heat dissipating element (7);

[0080] - a connection flange (11) connected to the outer enclosure plate (3), which provides support to both the heat sink (7) and the steam generator (8);

[0081] - a drive element (12), consisting of:

[0082] - a rotating shaft (13) passing through the outer enclosure plate (3) closing the tank (1) through a connection flange (14) and extending into the interior of the tank (1); and

[0083] - a rotor (15) located at one end of the rotating shaft (13), which produces, depending on its design and direction of rotation, a downward movement of the molten salts (2).

[0084] Furthermore, said installation may comprise a sleeve (16) of prismatic or cylindrical configuration, made of steel that is concentric with the axis of the tank (1) and runs vertically from the lower area of ​​the latter to its upper area, without reaching the salt level (2) or the bottom of the tank (1), housing inside it all the functional units (6) and the drive element (12).In this possible embodiment, the sleeve (16) has inside, arranged perpendicular to the longitudinal axis, a group of flat metallic inner plates (19, 20) placed equidistant from each other, where the inner plates (19, 20) are of two types that alternate vertically, a first plate (19), whose outer perimeter closes with the inner surface of the sleeve (16) and has an orifice in its central area through which there may be a flow of molten salts (2); and a second plate (20), whose outer perimeter encloses a section smaller than that of the sleeve (16), establishing between the second plate (20) and the inner surface of the sleeve (16) a free section through which a flow of molten salts (2) is produced.

[0085] In the installation, the heat dissipating element (7) can be an electrical resistor in the form of an elongated bar.

Claims

CLAIMS 1. Installation for storing thermal energy from electrical energy for the generation of process steam, characterized in that it comprises: a cylindrical atmospheric tank (1) containing a volume of molten salts (2) inside; an upper enclosure (21) of the tank (1) comprising openings (22) with flanged connections (5); a plurality of functional elements (6), installed in the openings (22) with flanged connections (5) and selected from at least one heat dissipating element (7) and / or at least one steam generator (8), and the functional elements (6) are partially submerged in the volume of molten salts (2), and where each functional element (6) comprises a salt circulation system with: an envelope (30) surrounding the heat dissipating element (7) or the steam generator (8), with one end arranged outside the tank (1), and the casing (30) comprises a salt inlet section (31) and an outlet section (32); a drive element (12) configured to aspirate the molten salts (2) from the inside of the tank (1) and propel them to the inlet section (31) of the casing (30); a set of partitions (33), arranged alternately inside the casing (30), in a direction transverse to the longitudinal direction of the casing (30). 2.- Installation according to claim 1, wherein, when the functional elements (6) are heat dissipating elements (7), they are electrical resistors comprising a plurality of longitudinal conductors (24) that extend longitudinally from the outside of the tank (1) to a certain depth inside the tank (1) in which they are submerged in the molten salts (2). 3.- Installation according to claim 1, wherein, when the functional elements (6) are steam generators (8), they comprise a steel conduit (25) with a water inlet, through which liquid water circulates downwards to a collector (26) and, from said collector (26) a plurality of vertical tubes (27) extend, through which A two-phase water-steam mixture circulates upwards to a steam collector (28), arranged in an upper section of the steam generator (8), where there is a steam outlet duct (29). 4.- Installation according to any one of the preceding claims, in which an upper section of the casing (30), in which the end of the casing (30) that is arranged on the outside of the tank (1) is located, is integral with the support plate (23). 5.- Installation according to any one of the preceding claims in which the functional elements (6) have a longitudinal configuration and extend from the outside of the tank (1) to a certain depth inside the tank (1) in which they are submerged in the volume of molten salts (2). 6.- Installation according to claim 5, wherein the salt driving element (12) has a longitudinal axis that is parallel to the longitudinal axes of the functional elements (6). 7.- Installation according to any one of the preceding claims in which the functional elements (6) are distributed homogeneously in the tank (1) with respect to a central longitudinal axis of the tank (1). 8.- Installation according to claim 3, wherein the steam generator (8) comprises an inert gas inlet (34) in an upper section of the steam generator (8) which is arranged outside the tank (1). 9.- Installation according to one of claims 3 or 8 comprising a pressure tank (35) connected to each steam generator (8) by its upper section which is arranged outside the tank (1), and pressure regulating valves (36) are arranged in each connection. 10.- Installation according to claim 9 comprising a relief valve (37) in the connections between the pressure tank (35) and the steam generators (8). 11.- Installation according to any one of the preceding claims, wherein the salt inlet section (31) and the salt outlet section (32) are arranged in a section of the casing (30) that is housed in the tank (1). 12.- Installation according to claim 11, wherein at least the salt outlet section (32) is submerged in the volume of molten salts (2) and the inlet section (31) is arranged at a height greater than that of the salt outlet (32). 13.- Installation according to any one of the preceding claims in which the support plate (23) is supported on a structure independent of the upper enclosure (21) of the tank (1).

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