THERMAL ENERGY STORAGE DEVICE

Abstract

Provided is a thermal energy storage device including a passage for the circulation of a heat transporting fluid between a hot end and a cold end, the hot end being configured for storing thermal energy at a first temperature (T1), the cold end being configured for storing thermal energy at a second temperature lower than the first temperature (T1). The thermal energy storage device includes a heating device at the hot end.

Claims

1. A heat accumulator for a thermal energy storage plant, the heat accumulator comprising: a passage for the circulation of a heat transporting fluid between a hot end and a cold end, and the hot end being configured for storing thermal energy at a first temperature, the cold end being configured for storing thermal energy at a second temperature lower than the first temperature, wherein the heat accumulator comprises a heating device at the hot end.

2. The heat accumulator according to claim 1, wherein the hot end comprises a lattice separating an inside and an outside of the heat accumulator, the heating device being provided on the lattice.

3. The heat accumulator according to claim 1, wherein the heating device is inductive or resistive.

4. The heat accumulator according to claim 1, wherein the heating device comprises a plurality of sections, each section being configured to be heated independently from the other sections.

5. The heat accumulator according to claim 4, wherein the heating device comprises a plurality of vertically distributed sections to individually control the heat addition distribution at the cross section of the hot end.

6. A thermal energy storage plant comprising: a piping where a heat transporting fluid is circulated, and the heat accumulator according to claim 1, for storing the thermal energy of the heat transporting fluid, the heat accumulator being connected to the piping, wherein an outlet of the piping is connected to the hot end of the heat accumulator.

7. The thermal energy storage plant according to claim 6, wherein the thermal energy storage plant includes a charging circuit comprising: the piping, the heat accumulator, and a fluid transporting machine configured for generating a flow of the heat transporting fluid from the hot end to the cold end.

8. The thermal energy storage plant according to claim 6, wherein the thermal energy storage plant includes a discharging circuit comprising: the piping, the heat accumulator, the fluid transporting machine configured for generating a flow of the heat transporting fluid from the cold end to the hot end, and a heat exchanger for receiving the thermal energy from the heat transporting fluid.

Description

BRIEF DESCRIPTION

[0041] Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

[0042] FIG. 1 shows a schematic diagram of a thermal energy storage plant, according to an exemplary embodiment of the present invention;

[0043] FIG. 2 shows a schematic diagram of the thermal energy storage plant of FIG. 1, in another operative configuration; and

[0044] FIG. 3 shows a schematic view of a component of the thermal energy storage plant of FIG. 1.

DETAILED DESCRIPTION

[0045] The illustration in the drawing is schematically. It is noted that in different figures, similar or identical elements or features are provided with the same reference signs. In order to avoid unnecessary repetitions elements or features which have already been elucidated with respect to a previously described embodiment are not elucidated again at a later position of the description.

[0046] FIGS. 1 and 2 schematically show a thermal energy storage plant 10 where a heat transporting fluid is circulated.

The heat transporting fluid may be, in particular, constituted by air or another gas suitable for transporting thermal energy.

[0047] The thermal energy storage plant 10 includes a heat accumulator 100, a piping 110, a fluid transporting machine 140 (when the heat transporting fluid is air or another gas, the fluid transporting machine 140 may be constituted by a fan or blower), a heat exchanger 150 and a plurality of valves 21, 31, 41, 51, arranged as specified in the following.

[0048] The thermal energy storage plant 10 includes three branches 20, 30, 40 in parallel to each other, all three extending between a first node 13 and a second node 14 of the thermal energy storage plant 10.

[0049] A first branch 20 extending between the two nodes 13, 14 comprises: [0050] the heat accumulator 100 in an intermediate position between the first node 13 and a second node 14, [0051] a first valve 21 interposed between the heat accumulator 100 and the second node 14 of the thermal energy storage plant 10.

[0052] The first node 13, the heat accumulator 100, the first valve 21 and the second node 14 are respectively connected in series by respective portions of the piping 110. The piping 110 comprises an outlet 111 connected to the hot end 101 of the heat accumulator 100.

[0053] The heat accumulator 100 is configured as a vessel extending between a hot end 101 and a cold end 102 and oriented in such a way that a portion of the piping 110 directly connects the first node 13 to the hot end 101 and another portion of the piping 110 directly connects the cold end 102 to the first valve 21.

[0054] The heat accumulator 100 is hollow and contains a plurality of heat storing elements having high thermal capacity, for example solid or bulk materials like stones, bricks, ceramics, and other solid materials, which have the ability to be heated up and to keep their temperature over a long period of time in order to store the thermal energy which has been transferred to them through the heat transporting fluid. At the interface between the piping 110 and the hot end 101, a heating device 120 is provided for heating the heat transporting fluid which enters the heat accumulator 100, during a charging phase. Inside the heat accumulator 100, the thermal energy of the heat transporting is transferred to the heat storing elements.

[0055] The heating device 120 is integrated in the heat accumulator 100, at the hot end 101.

[0056] The heating device 120 may be provided on a lattice comprised at the hot end 101 of the heat accumulator 100, the lattice separating an inside and an outside of the heat accumulator 100.

[0057] The heating device 120 permits the first hot temperature T1 and the second cold temperature T2 to be established between the hot end 101 and cold end 102 of the heat accumulator 130. According to possible embodiments of the present invention, typical values are T1=600° C. and T2=120° C. In other possible embodiments, values of T2 may be close to ambient temperature or 300° C.

[0058] The heating device 120 may comprises a plurality of sections, each section being configured to be heated independently from the other sections. Such feature of the heating device 120 makes it possible to control the local distribution of the heat addition into the heat accumulator 100. If the heat accumulator 100 is oriented horizontally and if a lower part of the heat accumulator 100 is colder than an upper part, the heating device 120 can be controlled so that only the lower part of the lattice is heated. Therefore, if the heat accumulator 100 is oriented horizontally, the heating device 120 may comprises a plurality of vertically distributed sections.

[0059] A second branch 30 extending between the two nodes 13, 14 comprises a second valve 31 interposed between the first node 13 and a second node 14.

[0060] The first node 13, the second valve 31 and the second node 14 are respectively connected in series by respective portions of the piping 110.

[0061] A third branch 40 extending between the two nodes 13, 14 comprises: [0062] a heat exchanger 150 for receiving thermal energy from the heat transporting fluid during a discharge phase, [0063] a third valve 41, [0064] the fluid transporting machine 140.

[0065] The first node 13, the heat exchanger 150, the third valve 41, the fluid transporting machine 140 and the second node 14 are respectively connected in series by respective portions of the piping 110.

[0066] According to embodiments of the present invention, the heat exchanger 150 is a steam generator for transferring thermal energy from the heat transporting fluid to a mass of water in order to generate steam to be fed to the thermal machine (not shown in the attached figures. The thermal machine may be a steam turbine having an output shaft connected to an electrical generator to produce electricity to be fed in an electricity grid.

[0067] According to another possible embodiment, the heat exchanger 150 is a boiler or an evaporator or other type of heat exchanger for receiving heat from the heat transporting fluid. The thermal energy storage plant 10 further includes a by-pass branch 50 for connecting the first branch 20 and the third branch 40. The by-pass branch 50 includes a fourth valve 51. The by-pass branch 50 extends between a section of the first branch 20 comprised between the heat accumulator 100 and the first valve 21 and a section of the third branch 40 comprised between the third valve 41 and the fluid transporting machine 140.

[0068] The charging phase of the thermal energy storage plant 10 is performed through a charging circuit 11 (FIG. 1) obtained by closing the first valve 21 and the third valve 41 and by opening the second valve 31 and the fourth valve 51 in the above-described thermal energy storage plant 10.

[0069] In the charging circuit 11 the fluid transporting machine 140 generates a flow of the heat transporting fluid, which through the second branch 30 reaches the interface between the piping 110 and hot end 101 of the heat accumulator 100, where the heating device 120 is provided. The heat transporting fluid is heated by the heating device 120 and enters the heat accumulator 100 for transferring the thermal energy received from the heating device 120 to the heat storing elements inside the heat accumulator 100. Downstream the cold end 102 of the heat accumulator 100, the heat transporting fluid returns to the fluid transporting machine 140 through the by-pass branch 50.

[0070] The discharging phase of the thermal energy storage plant 10 is performed through a discharging circuit 12 (FIG. 2) obtained by opening the first valve 21 and the third valve 41 and by closing the second valve 31 and the fourth valve 51 in the above-described thermal energy storage plant 10.

[0071] In the discharging circuit 12 the fluid transporting machine 140 generates a flow of the heat transporting fluid, which through the first valve 21 reaches the cold end 102 of the heat accumulator 100. The heat transporting fluid crosses then the heat accumulator 100 from the cold end 102 to the hot end 101, i.e. in opposite direction with respect to the flow of the heat transporting fluid in the charging circuit 11. Inside the heat accumulator 100, during the discharge phase, the heat transporting fluid receives thermal energy from the heat storing elements inside the heat accumulator 100. Such thermal energy is transported from the heat transporting fluid to the heat exchanger 150. Downstream the heat exchanger 150 the heat transporting fluid returns to the fluid transporting machine 140 through the third valve 41.

[0072] FIG. 3 schematically shows an embodiment of the heater 120. At the interface between the piping 110 and the hot end 101 a lattice or grid 120 is provided for separating the inside of the heat accumulator 100 and the piping 110, thus avoiding that the heat storing elements inside the heat accumulator 100 are not exiting the heat accumulator 100 and entering the piping 110. The heating device is provided on the lattice or grid 120. The lattice or grid 120 can be heated up inductively or it can function as a resistance heater.

[0073] Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.

[0074] For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.