A double-layer structure molten salt storage tank

Abstract

The application discloses a double-layer structure molten salt storage tank, and belongs to the field of molten salt energy storage. The double-layer structure molten salt storage tank comprises an inner tank body with an inlet pipe and an outlet pipe, an outer tank body connected to the outer side of the inner tank body, a side hollow area formed between the side of the inner tank body and the side of the outer tank body, a bottom hollow area formed between the bottom of the inner tank body and the bottom of the outer tank body, wherein the bottom hollow area and the side hollow area are communicated, a plurality of heating pipes located in the bottom hollow area, wherein the heating pipes are connected to the outer tank body, a plurality of condensing pipes, wherein the condensing pipes are inserted into the inner tank body, and the condensing pipes are communicated with the bottom hollow area, and a phase change working medium located in the side hollow area, the bottom hollow area and the condensing pipes. The application has the technical effects that it is convenient to prevent the heating pipes from over-temperature failure and reduce the heat dissipation.

Description

Technical Field

[0001] This invention relates to molten salt energy storage, and more particularly to a double-layered molten salt storage tank. Background Technology

[0002] Molten salt storage tanks are large pressure vessels specifically designed for storing molten salt, which has advantages such as high thermal density and high thermal temperature.

[0003] Heating tubes are an important component of molten salt storage tanks, mainly used to heat molten salt. However, these heating tubes are generally directly immersed in the molten salt. Since the molten salt in the tank is not flowing, the heat flux density on the surface of the heating tubes cannot be increased, which can easily lead to overheating and failure of the heating tubes. The only way to compensate for the heating power is to increase the number of heating tubes, which is inefficient. At the same time, the heat dissipation of the molten salt storage tank is large, which can easily cause high energy loss. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a double-layer molten salt storage tank, which not only helps prevent the heating tube from overheating and failing, but also helps reduce heat dissipation.

[0005] Technical solution: A double-walled molten salt storage tank, comprising: An inner tank with an inlet pipe and an outlet pipe; An outer tank body connected to the body of the inner tank body; A hollow side region formed between the side of the inner tank and the side of the outer tank; A bottom hollow region is formed between the bottom of the inner tank and the bottom of the outer tank, and the bottom hollow region is connected to the side hollow region; Several heating tubes are located within the hollow area at the bottom, and the heating tubes are connected to the outer tank. A plurality of condenser tubes are provided, the condenser tubes extending into the inner tank body and communicating with the bottom hollow area; The phase change working fluid is located in the side hollow region, the bottom hollow region, and the condenser tube. The heating tube is used to heat the liquid phase change working fluid in the bottom hollow region so that the liquid phase change working fluid reaches the phase change temperature and evaporates into a gaseous phase change working fluid. The gaseous phase change working fluid enters the side hollow region and the condenser tube.

[0006] Optionally, a plurality of the heating tubes are arranged at intervals around the circumference of the outer tank, and a plurality of condenser tubes are provided between adjacent heating tubes.

[0007] Optionally, the heating tubes include a plurality of first tubes and a plurality of second tubes, wherein the length of the first tubes is greater than the length of the second tubes, and the first tubes and the second tubes are staggered along the circumference of the outer tank.

[0008] Optionally, a plurality of the heating tubes are arranged in a stepped manner along the radial direction of the outer tank, and a plurality of condenser tubes are provided between adjacent heating tubes.

[0009] Optionally, adjacent heating tubes are interlocked.

[0010] Optionally, it may also include a plurality of support components connected to both the inner tank and the outer tank, the support components being located in the bottom hollow area, and the heating pipe being connected inside the support components.

[0011] Optionally, the support component includes: An annular portion that is connected to both the inner tank and the outer tank; A plurality of fins are spaced apart and connected to the outside of the annular portion; The annular portion and the fins are both located in the bottom hollow area, and the heating tube is connected inside the annular portion.

[0012] Optionally, the support assembly further includes a first support plate and a second support plate, with the annular portion and the inner tank connected by the first support plate, and the annular portion and the outer tank connected by the second support plate.

[0013] Optionally, it may also include an insulation layer wrapped around the outer tank.

[0014] Optionally, both the inlet pipe and the outlet pipe are connected to the top of the inner tank.

[0015] Beneficial effects: (1) The side hollow area and the condenser tube are used as the condensation heat dissipation section, and the bottom hollow area is used as the evaporation heat absorption section to form a heat pipe structure. The excellent thermal conductivity of the heat pipe structure makes it easy to expand the heating area and increase the heating power of the unit heating tube. Under the condition of meeting the overall heating power, it is easy to reduce the amount of heating tubes used and has high efficiency. At the same time, the state change of the phase change working fluid makes it easy to increase the heat flux density on the surface of the heating tube and effectively prevent the heating tube from overheating and failing. (2) The heating element of the traditional molten salt storage tank must be arranged at the bottom of the tank. Otherwise, when the molten salt level drops and the heating element cannot be submerged, dry burning will occur. This solution utilizes the good isothermal properties of the heat pipe structure, and the condensation heat dissipation section is maintained at the phase change temperature. There is no dry burning phenomenon, which makes it easy to arrange the condenser tubes in various positions of the molten salt and improve the heating uniformity. (3) In non-heating conditions, the phase change working fluid becomes liquid deposition, which makes the side hollow area present a near vacuum state, forming the best heat insulation layer, reducing the natural heat dissipation of molten salt, and improving the heat storage utilization rate. (4) During the heating stage, both the inner tank and the outer tank are heated to the phase change temperature of the phase change working medium. When entering the heat storage and utilization stage, the inner tank is insulated by vacuum insulation through the side hollow area, and the outer tank is insulated by the heat insulation layer, so that the temperature difference between the inner tank and the outer tank will not be too large, and the weld cracking will be prevented due to the large difference in thermal expansion between the two. Attached Figure Description

[0016] Figure 1 This is a structural diagram of a double-layer molten salt storage tank according to Embodiment 1 of the present invention; Figure 2 This is a structural diagram of the heating tube and condenser tube according to Embodiment 1 of the present invention; Figure 3 This is a structural diagram of the heating tube and condenser tube of Embodiment 2 of the present invention; Figure 4 This is a structural diagram of the support component according to Embodiment 1 of the present invention; Figure 5 yes Figure 4 Sectional view of AA; In the diagram: 1. Inner tank; 11. Inlet pipe; 12. Outlet pipe; 2. Outer tank; 31. Side hollow area; 32. Bottom hollow area; 4. Heating pipe; 41. First pipe; 42. Second pipe; 5. Condenser pipe; 6. Support assembly; 61. Circular part; 62. Fin; 63. First support plate; 64. Second support plate; 7. Insulation layer. Detailed Implementation

[0017] To make the technical solution of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. The terms "first," "second," etc., used in this invention are for the convenience of describing the technical solutions of the invention and have no specific limiting effect; they are all general terms and do not constitute a limitation on the technical solutions of the invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other. In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not contradict or conflict, all of which are within the scope of protection claimed by this invention.

[0019] Example 1 like Figure 1 This embodiment provides a double-layer molten salt storage tank, including: an inner tank 1 having an inlet pipe 11 and an outlet pipe 12; an outer tank 2 connected to the outside of the inner tank 1; a side hollow region 31 formed between the side of the inner tank 1 and the side of the outer tank 2; a bottom hollow region 32 formed between the bottom of the inner tank 1 and the bottom of the outer tank 2, the bottom hollow region 32 and the side hollow region 31 being connected; and a plurality of heating pipes 4 all located within the bottom hollow region 32. Heating tube 4 is connected to outer tank 2; several condensing tubes 5 extend into inner tank 1 and are connected to bottom hollow region 32; phase change working fluid is located in side hollow region 31, bottom hollow region 32 and condensing tubes 5. Heating tube 4 is used to heat the liquid phase change working fluid in bottom hollow region 32 so that the liquid phase change working fluid reaches the phase change temperature and evaporates into gaseous phase change working fluid. Gaseous phase change working fluid enters side hollow region 31 and condensing tubes 5.

[0020] Specifically, the inner tank 1 is used to store molten salt. The inlet pipe 11 facilitates the entry of molten salt into the inner tank 1, and the outlet pipe 12 facilitates the exit of molten salt from the inner tank 1. The outer tank 2 is used to enclose the inner tank 1. Both the inner tank 1 and the outer tank 2 can be made of austenitic stainless steel, etc. The side hollow region 31 is used to contain the gaseous phase change working fluid, thereby facilitating indirect heating of the molten salt in the inner tank 1. The side hollow region 31 also serves as a vacuum layer for heat insulation. The bottom hollow region 32 is used to contain the liquid phase change working fluid. The phase change working fluid is used in an evaporation-condensation cycle to indirectly heat the molten salt in the inner tank 1. The phase change working fluid can be liquid metals such as mercury, cesium, potassium, sodium, and lithium, or other liquids. For the mixed metals, it is important to note that the phase change temperature of the working fluid should be higher than the storage temperature of the molten salt. This ensures that when the heating tube 4 is not in operation, the storage temperature of the molten salt will not cause a phase change in the working fluid, allowing it to remain in a liquid state within the bottom hollow region 32. This, in turn, ensures that the side hollow region 31 serves as a vacuum layer for insulation. The heating tube 4 is used for indirect heating of the molten salt in the inner tank 1. The heating tube 4 is preferably a resistance type, and the number of heating tubes 4 is not limited; it can be ten, twelve, etc. The condenser tube 5 can be made of metal, inorganic materials, etc., with the main performance requirements being high temperature resistance and good thermal conductivity. The specific number of condenser tubes 5 is not limited.

[0021] The working principle of this application is illustrated below with an example. The double-layer molten salt storage tank of this embodiment stores binary molten salt. The storage temperature of the molten salt is 500°C, and the phase change working medium has a phase change temperature of 550°C. When the temperature exceeds 550°C, the phase change working medium evaporates and absorbs heat, and exists as a gas. When the temperature is below 550°C, it condenses and releases heat, and exists as a liquid.

[0022] (1) Heating and temperature rise conditions At the start of heating, the temperature of the molten salt in the inner tank 1 is 310°C. The heating tube 4 is activated, and the surface of the heating tube 4 gradually heats up to 600°C, and begins to heat the liquid phase change working fluid in the bottom hollow area 32, causing it to reach the phase change temperature of 550°C and evaporate and absorb heat. Subsequently, the gaseous phase change working fluid flows upward and enters the side hollow area 31 and the condenser tube 5, where it liquefies upon cooling and releases latent heat. The heat is transferred to the molten salt through the inner tank 1 and the condenser tube 5, gradually heating the molten salt to 500°C. This effectively increases the indirect heating area of ​​the heating tube 4 on the molten salt, thereby improving the heating efficiency.

[0023] (2) Thermal storage and utilization conditions During the heat storage stage, the heating tube 4 is not energized for heating, while the molten salt in the inner tank 1 can output heat for utilization. Since the phase change working fluid does not have a heat source and cannot reach the phase change temperature of 550°C, it is entirely liquid and accumulates in the bottom hollow area 32 under the action of gravity, making the side hollow area 31 present a near-vacuum state. This provides excellent heat insulation for the inner tank 1 and the outer tank 2, minimizing the heat loss of the molten salt and improving the heat utilization rate of the molten salt.

[0024] (3) Shutdown conditions When the system is not in operation, the molten salt will be stored in the inner tank 1 at a relatively low temperature of 310°C. The hollow side area 31 continues to act as a vacuum layer to provide insulation, minimizing the natural heat dissipation of the molten salt. Meanwhile, the outer tank 2 gradually decreases in temperature by dissipating heat to the outside, maintaining a small temperature difference with the inner tank 1, reducing the thermal expansion difference and decreasing the risk of weld cracking.

[0025] Furthermore, such as Figure 2 Several heating tubes 4 are arranged at intervals around the circumference of the outer tank 2, and there are multiple condenser tubes 5 between adjacent heating tubes 4.

[0026] Specifically, the circumferential spacing of several heating tubes 4 facilitates good heating uniformity; the presence of multiple condenser tubes 5 between adjacent heating tubes 4 facilitates good interleaving of heating tubes 4 and condenser tubes 5, thereby increasing the rationality of the layout and preventing them from being too dense or sparse, thus achieving the effect of heat balance; the specific number of heating tubes 4 and condenser tubes 5 is not limited, but the density of the condenser tubes 5 must be related to the density of the heating tubes 4, that is, areas with a large number of heating tubes 4 need to add condenser tubes 5 to maintain heat balance and prevent local overheating.

[0027] Furthermore, such as Figure 2 The heating tubes 4 include multiple first tubes 41 and multiple second tubes 42. The length of the first tube 41 is greater than the length of the second tube 42. The first tubes 41 and the second tubes 42 are staggered along the circumference of the outer tank 2.

[0028] Specifically, the longer first tube 41 and the shorter second tube 42 are staggered to prevent the heating tubes 4 in the center from being too dense and overheating. The number of first tubes 41 and the number of second tubes 42 must be equal.

[0029] Furthermore, such as Figure 4 It also includes several support components 6 that are connected to both the inner tank 1 and the outer tank 2. The support components 6 are located in the bottom hollow area 32, and the heating pipe 4 is connected to the support components 6.

[0030] Specifically, the support component 6 is used to support the weight of the inner tank 1 and the molten salt, and also to support the heating tube 4. The specific number of support components 6 is not limited, but it is necessary to ensure that the number of support components 6 is equal to the number of heating tubes 4.

[0031] Furthermore, such as Figure 5 The support assembly 6 includes: an annular portion 61 connected to both the inner tank 1 and the outer tank 2; and a plurality of fins 62 spaced apart from the annular portion 61; wherein the annular portion 61 and the fins 62 are both located within the bottom hollow region 32, and the heating tube 4 is connected within the annular portion 61.

[0032] Specifically, the annular portion 61 is used to wrap around the heating tube 4, which helps to prevent the heating tube 4 from directly contacting the phase change working fluid in the bottom hollow area 32. It also allows the heating tube 4 to be pulled out directly from the annular portion 61 during maintenance or replacement, thus avoiding leakage of the phase change working fluid. The fins 62 are used to increase the heat transfer area, thereby improving the heating efficiency.

[0033] Furthermore, such as Figure 5 The support assembly 6 also includes a first support plate 63 and a second support plate 64. The annular part 61 and the inner tank 1 are connected by the first support plate 63, and the annular part 61 and the outer tank 2 are connected by the second support plate 64.

[0034] Specifically, the first support plate 63 and the second support plate 64 are used to connect the annular part 61 with the inner tank 1 and the outer tank 2.

[0035] Furthermore, such as Figure 1 It also includes the insulation layer 7 that wraps around the outer tank 2.

[0036] Specifically, during the heating stage, both the inner tank 1 and the outer tank 2 are heated to the phase change temperature of the phase change working medium. When entering the heat storage and utilization stage, the inner tank 1 is vacuum-insulated through the side hollow area 31, and the outer tank 2 is insulated through the insulation layer 7, so that the temperature difference between the inner tank 1 and the outer tank 2 is not too large, preventing the weld from cracking due to excessive thermal expansion difference between the two. The insulation layer 7 can be made of ceramic fiber cotton, rock wool, etc.

[0037] Example 2 like Figure 3 The heating element 4 and the condenser element 5 in this embodiment can be improved as follows compared with the technical solution of embodiment 1: Furthermore, several heating tubes 4 are arranged in a stepped manner along the radial direction of the outer tank 2, and there are multiple condenser tubes 5 between adjacent heating tubes 4.

[0038] Specifically, since the heating tubes 4 are arranged in a radial stepped manner, it is easy to achieve good heating uniformity. The heating tubes 4 can be inserted into each other or in the same direction. Since there are multiple condenser tubes 5 between adjacent heating tubes 4, it is easy to achieve good interlacing between heating tubes 4 and condenser tubes 5, thereby increasing the rationality of the layout and preventing them from being too dense or sparse, so as to achieve the effect of heat balance.

[0039] Furthermore, adjacent heating tubes 4 are preferably interlocked.

[0040] Specifically, since the adjacent heating tubes 4 are preferably interlocked, it is convenient to further increase the heating uniformity. At the same time, it is convenient to place the wiring harnesses of the adjacent heating tubes 4 on both sides of the outer tank 2, thereby preventing the wiring harnesses of the adjacent heating tubes 4 from interfering with each other.

[0041] Furthermore, such as Figure 1 Both the inlet pipe 11 and the outlet pipe 12 are connected to the top of the inner tank 1.

[0042] Specifically, since both the inlet pipe 11 and the outlet pipe 12 are connected to the top of the inner tank 1, it is easy to prevent the inlet pipe 11 and the outlet pipe 12 from interfering with the side hollow area 31 and the bottom hollow area 32, thereby increasing the convenience of processing.

[0043] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A double-layered molten salt storage tank, characterized in that, include: An inner tank (1) having an inlet pipe (11) and an outlet pipe (12); an outer tank (2) connected to the outside of the inner tank (1); a side hollow region (31) formed between the side of the inner tank (1) and the side of the outer tank (2); a bottom hollow region (32) formed between the bottom of the inner tank (1) and the bottom of the outer tank (2), the bottom hollow region (32) and the side hollow region (31) being connected; all located in the bottom hollow region. A plurality of heating tubes (4) within region (32), the heating tubes (4) being connected to the outer tank (2); a plurality of condensing tubes (5), the condensing tubes (5) extending into the inner tank (1), the condensing tubes (5) being connected to the bottom hollow region (32); a phase change working fluid located in the side hollow region (31), the bottom hollow region (32), and the condensing tubes (5), the heating tubes (4) being used to heat the liquid phase change working fluid in the bottom hollow region (32). The liquid phase change working fluid is heated to reach the phase change temperature and evaporate into a gaseous phase change working fluid. The gaseous phase change working fluid enters the side hollow region (31) and the condenser (5). A plurality of heating tubes (4) are arranged circumferentially around the outer tank (2), and a plurality of condenser (5) are located between adjacent heating tubes (4). The tank also includes a plurality of support components (6) connected to both the inner tank (1) and the outer tank (2). The support components (6) are located at the... Within the hollow bottom region (32), the heating tube (4) is connected to the support assembly (6); the support assembly (6) includes: an annular portion (61) connected to both the inner tank (1) and the outer tank (2); and a plurality of fins (62) spaced apart from the annular portion (61); wherein the annular portion (61) and the fins (62) are both located within the hollow bottom region (32), and the heating tube (4) is connected to the annular portion (61).

2. The double-layered molten salt storage tank according to claim 1, characterized in that, The heating tubes (4) include a plurality of first tubes (41) and a plurality of second tubes (42), the length of the first tubes (41) being greater than the length of the second tubes (42), and the first tubes (41) and the second tubes (42) being staggered along the circumference of the outer tank (2).

3. A double-layered molten salt storage tank according to claim 1, characterized in that, Several heating tubes (4) are arranged in a stepped manner along the radial direction of the outer tank (2), and there are multiple condenser tubes (5) between adjacent heating tubes (4).

4. A double-layered molten salt storage tank according to claim 3, characterized in that, The adjacent heating tubes (4) are interlocked.

5. A double-layered molten salt storage tank according to claim 1, characterized in that, The support assembly (6) further includes a first support plate (63) and a second support plate (64). The annular portion (61) and the inner tank (1) are connected by the first support plate (63), and the annular portion (61) and the outer tank (2) are connected by the second support plate (64).

6. A double-layered molten salt storage tank according to any one of claims 1-4, characterized in that, It also includes an insulation layer (7) that wraps around the outer tank (2).

7. A double-layered molten salt storage tank according to any one of claims 1-4, characterized in that, Both the inlet pipe (11) and the outlet pipe (12) are connected to the top of the inner tank (1).

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