Integrated double-tank fused salt energy storage device

Abstract

The invention relates to an integrated double-tank fused salt energy storage device which comprises a first tank body, a second tank body, a first fused salt pump and a second fused salt pump, the first tank body is used for storing first fused salt, the second tank body is located in the first tank body and used for storing second fused salt, and the temperature of the second fused salt is higher than that of the first fused salt; a suction inlet of the first molten salt pump is inserted into the first tank body so as to convey first molten salt in the first tank body to the second tank body, and a suction inlet of the second molten salt pump is inserted into the second tank body so as to convey second molten salt in the second tank body to the first tank body. According to the integrated double-tank fused salt energy storage device, the low-temperature first fused salt storage tank and the high-temperature second fused salt storage tank are designed to be of an integrated structure, and the integrated double-tank fused salt energy storage device has the advantages of being compact in structure and small in occupied area. Compared with two independent fused salt storage tanks, the integrated double-tank fused salt energy storage device is small in external heat dissipation area and high in heat storage efficiency.

Description

Technical Field

[0001] The present invention relates to energy storage, and more particularly to an integrated double-tank molten salt energy storage device. Background Art

[0002] In recent years, molten salt energy storage has been increasingly used in solar thermal power stations and energy storage power stations. Traditional molten salt energy storage solutions generally use two independent vertical flat-bottomed atmospheric molten salt tanks installed side by side, one for low-temperature molten salt and one for high-temperature molten salt. Molten salt acts as a heat transfer medium, flowing between high and low temperature tanks to achieve heat storage and release functions. Obviously, this independent molten salt storage tank has disadvantages such as large surface area (large heat dissipation). Summary of the invention

[0003] In order to solve the problems of large heat dissipation and the like in the above-mentioned prior art, the present invention provides an integrated double-tank molten salt energy storage device.

[0004] According to the integrated double-tank molten salt energy storage device of the present invention, it includes a first tank body, a second tank body, a first molten salt pump and a second molten salt pump, wherein the first tank body is used to store the first molten salt, the second tank body is located inside the first tank body and is used to store the second molten salt, the temperature of the second molten salt is greater than the temperature of the first molten salt, the suction port of the first molten salt pump is inserted into the first tank body to transport the first molten salt in the first tank body to the second tank body, and the suction port of the second molten salt pump is inserted into the second tank body to transport the second molten salt in the second tank body to the first tank body. It should be understood that the first molten salt and the second molten salt are the same part of the molten salt, only the temperature is different.

[0005] In a preferred embodiment, the first tank body is a flat-bottomed annular container, and is provided with a first tank bottom, a first tank wall and a first tank top, wherein the first tank bottom is a planar structure, the first tank wall is an annular structure extending upward from the first tank bottom to define an annular space, the second tank body is located in the annular space, the first tank top closes the first tank wall at the top, and the first molten salt pump and the second molten salt pump are respectively installed on the first tank top.

[0006] In a preferred embodiment, a thermal insulation layer is provided outside the first tank wall and the first tank top.

[0007] In a preferred embodiment, the integrated double-tank molten salt energy storage device further includes a heat insulating support, which is installed below the bottom of the first tank.

[0008] In a preferred embodiment, the second tank body is a flat-bottom vertical atmospheric pressure container, and is provided with a second tank bottom and a second tank wall, wherein the second tank wall is an annular structure extending upward from the second tank bottom.

[0009] In a preferred embodiment, the second tank wall is an insulating tank wall.

[0010] In a preferred embodiment, the insulated tank wall comprises an outer layer and an insulating layer located within the outer layer.

[0011] In a preferred embodiment, the second tank body is not provided with a tank top.

[0012] According to the integrated double-tank molten salt energy storage device of the present invention, by designing the low-temperature first molten salt storage tank and the high-temperature second molten salt storage tank into an integrated structure, it has the advantages of compact structure and small footprint. Compared with two independent molten salt storage tanks, the integrated double-tank molten salt energy storage device of the present invention has a small external heat dissipation area and high heat storage efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall structure of an integrated double-tank molten salt energy storage device according to a preferred embodiment of the present invention.

[0014] Figure 2 yes Figure 1 A top-down cross-sectional view of an integrated dual-tank molten salt energy storage device.

[0015] Figure 3 yes Figure 1 Schematic diagram of the cross section of the insulated tank wall. DETAILED DESCRIPTION

[0016] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0017] like Figure 1-Figure 2 As shown, according to a preferred embodiment of the present invention, an integrated dual-tank molten salt energy storage device includes a first tank body 11, a second tank body 12, an insulating support 13, a first molten salt pump 14 and a second molten salt pump 15, wherein the first tank body 11 is used to store a first molten salt (i.e., low-temperature molten salt) to form a low-temperature molten salt storage tank, the second tank body 12 is located inside the first tank body 11 and is used to store a second molten salt (i.e., high-temperature molten salt) to form a high-temperature molten salt storage tank, the insulating support 13 is installed below the first tank body 11 to perform insulation and support functions, the suction port of the first molten salt pump 14 is inserted into the first tank body 11 to transport the low-temperature molten salt in the first tank body 11 to the second tank body 12, and the suction port of the second molten salt pump 15 is inserted into the second tank body 12 to transport the high-temperature molten salt in the second tank body 12 to the first tank body 11.

[0018] It should be understood that the integrated double-tank molten salt energy storage device according to the present invention has the advantages of compact structure and small footprint by designing the low-temperature molten salt storage tank and the high-temperature molten salt storage tank as an integrated structure. Compared with two independent molten salt storage tanks, the integrated double-tank molten salt energy storage device according to the present invention has a small external heat dissipation area and high heat storage efficiency. Moreover, the high-temperature molten salt storage tank is arranged inside, and there is no direct heat dissipation to the external environment, which can further improve the heat storage efficiency. In addition, the high-temperature molten salt storage tank, which is prone to failure, is arranged inside. Once a molten salt leakage failure occurs in the tank wall of the high-temperature molten salt storage tank, the molten salt will leak into the external low-temperature molten salt storage tank, and will not leak directly to the external environment, thereby improving the overall safety.

[0019] In this embodiment, the high-temperature molten salt and the low-temperature molten salt are both nitrates. It should be understood that nitrates are only used as an example and not as a limitation, and other molten salts such as carbonates, chlorides, and fluorides can be directly used for this.

[0020] In the present invention, the first tank body 11 is a flat-bottomed annular container, which is provided with a first tank bottom, a first tank wall and a first tank top, wherein the first tank bottom is a planar structure convenient for being placed on a flat thermal insulation support 13, the first tank wall is an annular structure extending upward from the first tank bottom to define an annular space, the second tank body 12 is located in the annular space, the first tank top closes the first tank wall at the top, and the first molten salt pump 14 and the second molten salt pump 15 are respectively installed on the first tank top.

[0021] In the present invention, an insulation layer 11a is provided on the outside of the first tank wall and the first tank top to reduce the heat exchange between the low-temperature molten salt storage tank and the external environment, thereby reducing heat loss and improving the overall efficiency of the energy storage system. In a preferred embodiment, the insulation layer 11a can be made of high-efficiency insulation materials, such as glass wool, rock wool or polyurethane foam, etc. These materials have low thermal conductivity and can significantly reduce heat transfer. The insulation layer 11a can be designed as a multi-layer structure and covered with a protective layer to prevent the insulation material from getting damp or damaged. It should be understood that according to the integrated double-tank molten salt energy storage device of the present invention, the heat dissipation of the molten salt storage tank to the outside can be effectively reduced and the heat storage efficiency can be improved through the insulation layer 11a and the insulation support 13 surrounded by the outside.

[0022] In the present invention, the second tank body 12 is a flat bottom vertical normal pressure container, and is provided with a second tank bottom and a second tank wall, wherein the second tank wall is an annular structure extending upward from the second tank bottom, has a large height, is suitable for vertical placement, and is used under normal pressure conditions. In this embodiment, the second tank bottom and the first tank bottom share the entire tank bottom of the corresponding area of ​​the bottom. It should be understood that it is also feasible to provide an independent second tank bottom with a planar structure placed on the flat first tank bottom.

[0023] In this embodiment, the second tank wall is an insulating tank wall 12a, which is used to reduce the heat transfer between the low-temperature molten salt storage tank and the high-temperature molten salt storage tank. Figure 3 As shown, the insulated tank wall 12a includes an outer layer 121 and an insulating layer 122 located in the outer layer 121. In the present embodiment, the outer layer 121 is a steel plate, and the insulating layer 122 is an insulating material filled in the steel plate, and the insulating material may be aluminum silicate ceramic fiber, insulating bricks, air, castables, etc. These insulating materials effectively reduce the transfer of heat from the high-temperature molten salt storage tank to the low-temperature molten salt storage tank through the characteristics of their low thermal conductivity, thereby reducing heat loss and improving the overall efficiency of the energy storage device. In other words, the inner side of the second tank wall close to the high-temperature molten salt and the outer side close to the low-temperature molten salt are both steel plates, and the insulating material in the middle can significantly reduce the thermal conductivity and reduce the heat transfer. It should be understood that the insulated tank wall 12a here is only an example and not a limitation, and it is also feasible to use a conventional metal tank wall. In particular, although there is a small amount of heat transfer between the high-temperature molten salt located inside and the low-temperature molten salt located outside, under normal heat storage or heat release conditions, only the height interval of the bottom molten salt dead zone has molten salt on both sides (and the molten salt at these two sides does not participate in the heat storage or heat release process), and the upper area has molten salt only on one side and gas on the other side. Therefore, the heat transferred between the two due to the temperature difference is very small, and the present invention can further reduce the heat transfer by insulating the tank wall 12a.

[0024] In this embodiment, the second tank body 12 is not provided with a tank top, which reduces the stress problem caused by thermal expansion, simplifies the structure, and reduces the cost. It should be understood that the working temperature of the second tank body 12 is high, and the thermal expansion is higher than that of the first tank body 11. If the first tank top of the first tank body 11 is directly used to form the tank top of the second tank body 12 (i.e., the second tank top), there is a large stress between the two, and a very large diameter bellows needs to be provided, which is expensive; if an independent second tank top is provided, the installation structure of the molten salt pumps 14 and 15 will become complicated.

[0025] In a preferred embodiment, the height of the first tank wall of the first tank body 11 is between 8 and 16 meters, which is determined according to the scale of the heat storage capacity. The height of the first tank body 11 is affected by the length of the first molten salt pump 14. Usually, the total length of the first molten salt pump 14 is about 17 meters, so the height of the first tank wall does not exceed 16 meters. In a preferred embodiment, the height of the second tank wall of the second tank body 12 is 20cm-50cm lower than the height of the first tank wall of the first tank body 11. It should be understood that the heat storage capacity is determined according to the scale of the project, and then the volume of the molten salt is determined according to the working temperature difference, the specific heat capacity of the molten salt, the density, etc., and the area of ​​the first tank bottom is calculated in combination with the height, so as to determine the diameter of the first tank bottom, so that the external heat dissipation area of ​​the first tank body 11 is minimized, that is, the heat dissipation of the first tank body 11 to the outside is minimized.

[0026] In this embodiment, the heat insulation support 13 is a soft heat insulation support made of ceramsite. It should be understood that the soft heat insulation support is only used as an example and not as a limitation, and a hard heat insulation support made of high-temperature casting material can also be directly used for this.

[0027] In the present invention, the first molten salt pump 14 has a first suction pipe 141 and a first outlet pipe 142 that are connected, wherein the suction port of the first suction pipe 141 is inserted into the bottom of the first tank body 11, and the outlet of the first outlet pipe 142 is inserted into the bottom of the second tank body 12, thereby transporting the low-temperature molten salt in the first tank body 11 to the second tank body 12.

[0028] In the present invention, the outlet of the first molten salt pump 14 is connected to a heater 143, and the low-temperature molten salt is heated by the heater 143 and flows into the inner second tank 12. The heater 143 can be an electric heater or a heat exchanger, and the heat exchanger can transfer heat from a high-temperature heat transfer medium to the low-temperature molten salt, and the high-temperature heat transfer medium can be water, steam, heat transfer oil, molten salt, gas, etc.

[0029] In a preferred embodiment, the distance between the inlet of the first suction pipe 141 and the bottom of the first tank is between 0.5m-1m, and the distance from the first tank wall is 1 / 3-2 / 3 of the radius. The outlet of the first outlet pipe 142 is arranged in the distribution ring pipe of the second tank bottom, and the distance from the second tank bottom is between 0.2m-0.5m, which effectively reduces the heat loss of the molten salt during the pumping process and ensures the smooth flow of the molten salt.

[0030] In the present invention, the second molten salt pump 15 has a connected second suction pipe 151 and a second outlet pipe 152, wherein the suction port of the second suction pipe 151 is inserted into the bottom of the second tank body 12, and the outlet of the second outlet pipe 152 is inserted into the bottom of the first tank body 11, thereby transporting the high-temperature molten salt in the second tank body 12 to the first tank body 11.

[0031] In the present invention, the outlet of the second molten salt pump 15 is connected to a heat exchanger 153, and the high-temperature molten salt is cooled by heat exchange in the heat exchanger 153 and then flows into the first tank 11 on the outside. In the heat exchanger 153, the high-temperature molten salt exchanges heat with the medium on the other side, and the medium on the other side flows out after being heated by the molten salt. The medium on the other side is generally water or steam.

[0032] In a preferred embodiment, the distance between the inlet of the second suction pipe 151 and the bottom of the second tank is between 0.5m-1m, and the distance from the second tank wall is 1 / 3-2 / 3 of the radius. The outlet of the second outlet pipe 152 is arranged in the distribution ring pipe of the bottom of the first tank, and the distance from the bottom of the first tank is between 0.2m-0.5m, which effectively reduces the heat loss of the molten salt during the pumping process and ensures the smooth flow of the molten salt.

[0033] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. An integrated double-tank molten salt energy storage device, characterized in that: The integrated dual-tank molten salt energy storage device includes a first tank body, a second tank body, a first molten salt pump and a second molten salt pump, wherein the first tank body is used to store a first molten salt, the second tank body is located inside the first tank body and is used to store a second molten salt, the temperature of the second molten salt is greater than the temperature of the first molten salt, the suction port of the first molten salt pump is inserted into the first tank body to transport the first molten salt in the first tank body to the second tank body, and the suction port of the second molten salt pump is inserted into the second tank body to transport the second molten salt in the second tank body to the first tank body.

2. The integrated double-tank molten salt energy storage device according to claim 1 is characterized in that: The first tank body is a flat-bottomed annular container, which is provided with a first tank bottom, a first tank wall and a first tank top, wherein the first tank bottom is a planar structure, the first tank wall is an annular structure extending upward from the first tank bottom to define an annular space, the second tank body is located in the annular space, the first tank top closes the first tank wall at the top, and the first molten salt pump and the second molten salt pump are respectively installed on the first tank top.

3. The integrated double-tank molten salt energy storage device according to claim 2 is characterized in that: A heat-insulating layer is arranged outside the first tank wall and the first tank top.

4. The integrated double-tank molten salt energy storage device according to claim 1 is characterized in that: The integrated double-tank molten salt energy storage device also includes a heat-insulating support installed below the bottom of the first tank.

5. The integrated double-tank molten salt energy storage device according to claim 1 is characterized in that: The second tank body is a flat-bottom vertical atmospheric pressure container, which is provided with a second tank bottom and a second tank wall, wherein the second tank wall is an annular structure extending upward from the second tank bottom.

6. The integrated double-tank molten salt energy storage device according to claim 5 is characterized in that: The second tank wall is a heat-insulating tank wall.

7. The integrated double-tank molten salt energy storage device according to claim 6 is characterized in that: The insulated tank wall includes an outer layer and an insulating layer located within the outer layer.

8. The integrated double-tank molten salt energy storage device according to claim 5, characterized in that: The second tank body is not provided with a tank top.

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