Spherical storage tank for high-temperature molten salt

Abstract

The utility model discloses a spherical storage tank for high-temperature molten salt. The spherical storage tank comprises a foundation, the foundation is in a circular ring shape, and a supporting column is fixedly arranged on the foundation. The supporting columns are uniformly distributed on the foundation; one end of the supporting column is fixedly connected with the foundation, the other end of the supporting column is fixedly connected with the spherical tank body, the spherical tank body is fixedly arranged above the foundation, the foundation is separated from the spherical tank body, and high temperature of the tank body cannot be conducted to the foundation; the surface of the spherical tank body is uniformly covered with an insulating layer; and the spherical tank body is used for storing high-temperature molten salt. According to the spherical storage tank for the high-temperature molten salt, the spherical tank body supported in an overhead mode is used, the tank body and the foundation are physically isolated, the spherical storage tank adapts to a high-temperature molten salt medium, internal stress of the spherical tank wall is small and even, thermal stress brought by the high-temperature medium can be better borne, and safety accidents caused by leakage of the tank body are reduced; the device has the advantages of high loading capacity, uniform thermal stress distribution, high volume utilization rate, low cost and good thermal insulation effect.

Description

Technical Field

[0001] The utility model relates to the technical field of molten salt energy storage systems, in particular to a spherical storage tank for high-temperature molten salt. Background Art

[0002] With the adjustment of energy structure, more and more renewable energy sources are expanding their applications. Solar thermal power generation is an efficient form of solar power generation. Due to the high working temperature of its heat transfer medium molten salt and excellent energy quality, it has higher power generation efficiency. The molten salt used in solar thermal power stations is generally a mixture of 60% sodium nitrate and 40% potassium nitrate, and the melting point is generally 220°C. It has the advantages of low viscosity, small flow resistance, high specific heat capacity, strong heat storage capacity, and low production cost. The operating temperature of the tower thermal power station is generally 290°C to 565°C.

[0003] However, solar energy is an unstable energy source. In addition to being unavailable at night, it is also affected by weather conditions such as clouds during the day, and fluctuates greatly. To effectively solve this problem, solar thermal power stations are generally equipped with molten salt heat storage systems with sufficient capacity. Among them, the high-temperature molten salt storage tank is the core equipment in the heat storage system. It has many technical difficulties, is large in size and occupies the largest investment proportion.

[0004] Molten salt heat storage is currently mainly used in energy storage systems for solar thermal power generation, demonstrating the reliability and good economy of large-scale heat storage technology. In addition, molten salt heat storage can also be used in the thermal-electric decoupling scheme of industrial steam supply units. When the thermal power unit is operating normally, the main steam or high-temperature reheat steam is extracted for heat storage, and heat is released from the molten salt when the steam supply is at high load, thus achieving thermal-electric decoupling. There is also a thermal storage peak-shaving device for thermal power units, which extracts the main steam of the boiler for molten salt heat storage, and uses the heat to generate steam for small steam turbine power generation during heat release, thus achieving flexible peak-shaving of thermal power units.

[0005] However, the leakage problem of high-temperature molten salt storage tanks is very prominent, mostly due to local thermal stress concentration inside the tank and uneven foundation settlement leading to molten salt leakage.

[0006] The existing molten salt storage tanks are mostly vertical cylindrical in shape; the tanks have flat bottoms and non-pressure dome-type roofs; the tanks are placed on a ground foundation, such as Figure 1 As shown. The foundation is insulated; the tank wall is made of corrosion-resistant metal materials that are suitable for the working temperature. The traditional molten salt storage tank has problems such as uneven tank foundation settlement, direct contact between the metal bottom plate of the tank and the non-metallic tank bottom foundation, and different expansion characteristics.

[0007] Therefore, there is an urgent need to provide a new storage tank for high-temperature molten salt to reduce the leakage of high-temperature molten salt and improve the safety of molten salt storage. Utility Model Content

[0008] The purpose of the utility model is to provide a spherical storage tank for high-temperature molten salt in view of the deficiencies of the above-mentioned prior art, to achieve physical isolation between the tank body and the foundation, and to give full play to the technical advantages of the spherical tank, such as strong pressure bearing capacity, uniform thermal stress distribution, good economy, and adaptability to higher temperature parameters, so as to achieve safe non-contact between the spherical tank body and the foundation, reduce the mutual influence between the uneven settlement of the tank foundation and the tank body, and reduce the risk of safety accidents caused by tank leakage and major economic losses caused by the unit stopping operation due to tank leakage.

[0009] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0010] A spherical storage tank for high-temperature molten salt comprises a foundation; the foundation is in a circular shape and pillars are fixedly arranged on the foundation; the pillars are evenly distributed on the foundation; one end of the pillar is fixedly connected to the foundation and the other end is fixedly connected to the spherical tank body, the spherical tank body is fixedly arranged above the foundation, and the foundation and the spherical tank body are separated; high-temperature molten salt is stored in the spherical tank body.

[0011] Preferably, the foundation is a reinforced concrete structure.

[0012] Preferably, the spherical tank body includes a spherical shell, which is composed of steel plates and adopts an orange-segment structure or a mixed splicing structure, and the welds of the entire tank are evenly distributed.

[0013] Preferably, when the heat storage temperature of the high-temperature molten salt is ≤400°C, the steel plate is made of carbon steel; when the heat storage temperature of the high-temperature molten salt is >400°C, the steel plate is made of heat-resistant alloy steel. The heat-resistant alloy steel is preferably made of austenitic stainless steel.

[0014] Preferably, a hole is opened at the top of the spherical tank body near the upper pole to provide an inlet and outlet pipeline interface for high-temperature molten salt.

[0015] Preferably, the surface of the spherical tank body is evenly covered with a thermal insulation layer.

[0016] Preferably, the surface of the thermal insulation layer is evenly covered with an outer protective layer.

[0017] Preferably, one circle or two circles of pillars are evenly arranged on the foundation.

[0018] Preferably, the pillar is a steel structure, which is made of steel pipes in sections, and includes an upper pillar and a lower pillar; one side of the upper pillar is a concave curved surface, which is tangent to the contact surface of the spherical shell; an upper support ear is welded to the outer surface of the upper pillar; a filling layer is provided inside the upper pillar, which is filled with insulating material; the upper end of the lower pillar is welded or bolted to the lower end of the upper pillar, and the lower end is welded and fixed to the base plate; the base plate is fixedly connected to the foundation by anchor bolts; and a lower support ear is welded to the lower pillar near the base plate.

[0019] Preferably, adjacent pillars are connected by a cross tie rod; the cross tie rod is a steel pipe, one end of the steel pipe is fixedly connected to the upper ear of one pillar, and the other end is fixedly connected to the lower ear of the adjacent pillar.

[0020] Compared with the prior art, the beneficial effects of the utility model are:

[0021] The utility model discloses a spherical storage tank for high-temperature molten salt, which adapts to high-temperature molten salt medium by using an overhead supported spherical tank body and physically isolating the tank body from the foundation. The stress in the spherical tank wall is small and uniform, which can better withstand the thermal stress brought by the high-temperature medium and reduce safety accidents caused by tank leakage. The utility model has the advantages of strong pressure bearing capacity, uniform thermal stress distribution, large volume utilization rate, low cost and good thermal insulation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a basic structure diagram of a conventional molten salt storage tank in the prior art;

[0023] Figure 2 This is a schematic diagram of the structure of a spherical storage tank for high-temperature molten salt according to the utility model;

[0024] Figure 3 This is a schematic diagram of the structure of a support in a spherical storage tank for high-temperature molten salt according to the utility model;

[0025] Figure 4 This is a schematic structural diagram of a foundation in a spherical storage tank for high-temperature molten salt in a specific implementation manner of the utility model;

[0026] Figure 5 It is a schematic structural diagram of the foundation of a spherical storage tank for high-temperature molten salt in a specific implementation manner of the utility model.

[0027] In the figure: 1. spherical tank body; 11. spherical shell; 12. insulation layer; 13. pipe interface; 14. outer sheath; 2. pillar; 21. upper pillar; 211. filling layer; 212. upper support ear; 22. lower pillar; 221. lower support ear; 222. anchor bolt; 223. bottom plate; 3. cross tie rod; 4. foundation. DETAILED DESCRIPTION

[0028] The following is a detailed description of the implementation of the present invention in conjunction with the accompanying drawings, but they do not constitute a limitation of the present invention and are only examples. At the same time, the advantages of the present invention will become clearer and easier to understand through the description.

[0029] See attached Figure 2-5 It can be seen that the spherical storage tank for high-temperature molten salt of the utility model is mainly composed of a spherical tank body 1, a support 2 and a cross tie rod 3 thereof, and a foundation 4.

[0030] like Figure 4 and Figure 5 As shown, the foundation 4 is a circular foundation 4, forming a continuous arc beam. A support 2 is fixedly arranged on the foundation 4, one end of the support 2 is fixedly connected to the foundation 4, and the other end is fixedly connected to the spherical tank body 1. The spherical tank body 1 is fixedly arranged above the foundation 4, and the foundation 4 is separated from the spherical tank body 1, so that the high temperature of the tank body cannot be transmitted to the foundation 4. The foundation 4 is a reinforced concrete structure, and the working temperature is room temperature.

[0031] like Figure 2-3 As shown, the spherical tank body 1 is spherical, including a spherical shell 11, which is welded by splicing steel plates. The welds of the whole tank are evenly distributed, and the splicing scheme can adopt orange segment type or mixed type splicing. Since the construction of large-volume spherical tanks is more difficult, under the premise that the total volume of the storage tank is determined, whether to use a single tank or multiple tanks is determined after technical and economic comparison. The material of the steel plate used in the spherical shell 11 is adapted to the heat storage temperature of the molten salt: if the heat storage temperature of the molten salt is ≤400℃, carbon steel is used; if the heat storage temperature of the molten salt is >400℃, austenitic stainless steel or other heat-resistant alloy steel is used. The thickness of the steel plate takes into account a certain corrosion margin according to the type of molten salt stored.

[0032] A hole is opened at the top of the spherical tank body 1 near the upper pole to provide an inlet and outlet pipe interface 13 for the molten salt, and the interface is reinforced according to finite element analysis.

[0033] The surface of the spherical tank body 1 is evenly covered with an insulation layer 12 to control the heat dissipation of the spherical tank body 1. The insulation layer 12 adopts a double-layer composite insulation structure of aluminum silicate and glass wool insulation felt, and is fixed to the tank body with insulation hooks and binding belts.

[0034] An outer protective layer 14 may be further provided outside the thermal insulation layer 12, and the outer protective layer 14 is made of a color steel plate or an aluminum alloy plate.

[0035] The pillars 2 are evenly distributed in the lower part of the spherical tank body 1. The specific gravity of molten salt is relatively large, about twice that of water, so the load of the storage tank is relatively large, and it is necessary to increase the bearing capacity of a single pillar 2 or increase the number of pillars 2 to support the spherical tank body 1. When there are more pillars 2, an inner and outer two or more rings can be arranged. In one specific embodiment, eight pillars 2 are provided, which are equidistantly distributed and fixed on the circular foundation 4. In another specific embodiment, the pillars 2 are provided with inner and outer two circles, the inner circle includes four pillars 2, and the outer circle includes eight pillars 2. The inner and outer circles are evenly distributed and fixed on the circular foundation 4.

[0036] The support 2 is a steel structure, which is made of steel pipes in sections, and includes an upper support 21 and a lower support 22. The upper support 21 is made of carbon steel or austenitic stainless steel or other heat-resistant alloy steel of the same material as the spherical shell 11, and the lower support 22 is carbon structural steel. One side of the upper support 21 is a concave curved surface, which is tangent to the contact surface of the spherical shell 11, and is used to contact and cooperate with the surface of the spherical shell 11 to increase the force-bearing area of ​​the support 2 and the surface of the spherical tank body 1. An upper support ear 212 is welded to the outer surface of the upper support 21. A filling layer 211 is provided inside the upper support 21, which is filled with insulation material, and the insulation material is aluminum silicate wool insulation material. The upper end of the lower support 22 is welded or bolted to the lower end of the upper support 21, and the lower end is welded and fixed to the bottom plate 223, and the bottom plate 223 is fixedly connected to the foundation 4 through anchor bolts 222. A lower support ear 221 is welded to the lower support 22 near the bottom plate 223. The joint between the upper support 21 and the lower support 22 can be provided with refractory material, and the refractory material is a hard heat-insulating material of aluminum silicate board.

[0037] Adjacent pillars 2 are connected by cross tie rods to form a structural system. The cross tie rods are made of steel pipes, one end of which is connected to the upper lug 212 of a pillar 2, and the other end is connected to the lower lug 221 of the adjacent pillar 2 in the same circle, so that the entire spherical tank body 1 and the foundation 4 form a structural system. The steel pipe can be connected to the upper lug 212 and the lower lug 221 by hinges or bolts. The structural design of the entire spherical tank body 1 and the foundation 4 should be checked according to the specifications for wind load, earthquake and foundation 4 settlement conditions.

[0038] The spherical storage tank provided by the utility model can be used in various energy systems, and is a spherical metal storage tank with high-temperature molten salt (including binary salt, ternary salt and other new molten salt) as a heat storage medium. Including but not limited to the energy storage system used to balance the instability of solar thermal resources in solar thermal power stations, the molten salt storage tank used to store compressed heat in compressed air energy storage power stations, and the molten salt storage tank in the heat storage system for realizing flexible peak load regulation and flexible heating in thermal power plants.

[0039] Compared with vertical cylindrical storage tanks, the spherical storage tank of the utility model has the smallest surface area of ​​the spherical tank body 1 under the same volume and the same pressure, so the required steel area is small; the steel plates and welds are evenly distributed throughout the tank, and are uniform. Under the same diameter, the stress in the spherical tank wall is the smallest and uniform, and can better withstand the thermal stress caused by the high-temperature medium in the tank. Many conventional molten salt storage tank leakage accidents occur at the bottom of the tank: the bottom and the tank wall of conventional cylindrical tanks are corner welds, and the flat tank bottom is prone to uneven expansion at high temperatures, causing deformation and cracking. The utility model spherical storage tank can avoid the occurrence of cracking at the bottom of the tank and improve the safety of the tank.

[0040] The load-bearing capacity of the spherical storage tank of the utility model is greater than that of the cylindrical container with the same diameter, so the plate thickness of the spherical tank body 1 is thinner than the wall thickness of the corresponding cylindrical container. From the above characteristics, it can be seen that the use of the spherical tank body 1 can greatly reduce the consumption of steel, generally saving 30-45% of steel; in addition, the spherical tank body 1 occupies a small area, the foundation 4 engineering volume is small, and the land area can be saved.

[0041] In the utility model, the volume utilization rate of the spherical tank body 1 is greater than that of the cylindrical tank. The larger the effective volume ratio is, the lower the cost is. The horizontal cross-sectional area of ​​the tank bottom of the spherical tank body 1 is gradually reduced, and the volume ratio of the tank bottom part is relatively small. For the same dead liquid level (the liquid level that the vertical long-axis molten salt pump cannot pump), the dead volume of the spherical tank body 1 is much smaller than that of the cylindrical tank. In order to improve the volume utilization rate, many conventional cylindrical storage tanks propose to partially recess the tank bottom, which is bound to aggravate the thermal stress concentration at the tank bottom and increase the risk of cracking and leakage at the tank bottom.

[0042] The utility model of the spherical storage tank for high-temperature molten salt has good insulation effect and is therefore more energy-efficient. The heat dissipation of the molten salt storage tank is one of the important factors affecting the energy storage efficiency. The molten salt storage tank generally requires that the temperature drop of the molten salt within 24 hours does not exceed 3°C. The bottom of the conventional vertical cylindrical storage tank is grounded and load-bearing, and it cannot be covered with suitable soft insulation materials like the tank wall and tank top. In addition, in order to reduce the temperature of the tank bottom foundation, cooling pipes are also required to dissipate heat. The heat dissipation of the bottom foundation of the conventional storage tank occupies the vast majority of the heat dissipation of the entire tank body. The temperature field of the molten salt medium in the lower part of the tank body is uneven. The molten salt near the bottom of the tank is prone to form an inclined temperature layer and solidifies first. The spherical tank body 1 proposed in the utility model is arranged overhead, and the entire tank body from the top to the bottom of the tank can be covered with uniform and reliable insulation materials, and the insulation project is simple and reliable.

[0043] The foundation 4 of the spherical storage tank of the utility model is separated from and not in contact with the tank body, and is supported by the steel pillars 2. The bottom of the spherical tank body 1 is spherical, not flat, and is supported by a circle of pillars 2 without direct contact with the foundation 4. The hollow steel pillars 2 can be built with insulation materials to effectively isolate the high-temperature heat conduction of the tank body. The foundation 4 of the pillars 2 adopts a circular ring-shaped concrete foundation 4. The foundation 4 has a small amount of engineering and is not affected by high temperatures. The foundation 4 can be designed and constructed according to conventional methods and is not affected by the thermal stress of the tank body. The circular ring-shaped foundation 4 of the spherical tank body 1 is more resistant to distortion and settlement than the large-diameter circular plate-shaped foundation 4.

[0044] Other parts not described belong to the prior art.

Claims

1. Spherical storage tank for high temperature molten salt, characterized by: The invention comprises a foundation (4); the foundation (4) is annular, and pillars (2) are fixedly arranged on the foundation (4); the pillars (2) are evenly distributed on the foundation (4); one end of the pillars (2) is fixedly connected to the foundation (4), and the other end is fixedly connected to the spherical tank body (1); the spherical tank body (1) is fixedly arranged above the foundation (4), and the foundation (4) is separated from the spherical tank body (1); and high-temperature molten salt is stored in the spherical tank body (1).

2. The spherical storage tank for high-temperature molten salt according to claim 1 is characterized in that: The foundation (4) is a reinforced concrete structure.

3. The spherical storage tank for high-temperature molten salt according to claim 1, characterized in that: The spherical tank body (1) comprises a spherical shell (11), which is composed of a steel plate and adopts an orange segment structure or a mixed splicing structure, and the welds of the entire tank are evenly distributed.

4. The spherical storage tank for high-temperature molten salt according to claim 3 is characterized in that: When the heat storage temperature of the high-temperature molten salt is ≤400°C, the steel plate is made of carbon steel; when the heat storage temperature of the high-temperature molten salt is >400°C, the steel plate is made of heat-resistant alloy steel.

5. The spherical storage tank for high-temperature molten salt according to claim 1, characterized in that: The top of the spherical tank body (1) is opened near the upper pole to provide an inlet and outlet pipeline interface (13) for high-temperature molten salt.

6. The spherical storage tank for high-temperature molten salt according to claim 1, characterized in that: The surface of the spherical tank body (1) is evenly covered with a heat-insulating layer (12).

7. The spherical storage tank for high-temperature molten salt according to claim 6, characterized in that: The surface of the thermal insulation layer (12) is evenly covered with an outer protective layer (14).

8. The spherical storage tank for high-temperature molten salt according to claim 1, characterized in that: The foundation (4) is evenly arranged with one circle or two circles of pillars (2).

9. The spherical storage tank for high-temperature molten salt according to claim 8, characterized in that: The support (2) is a steel structure, which is made of steel pipes in sections, and includes an upper support (21) and a lower support (22); one side of the upper support (21) is a concave curved surface, which is tangent to the contact surface of the spherical shell (11); an upper support ear (212) is welded to the outer surface of the upper support (21); a filling layer (211) is arranged inside the upper support (21) and filled with insulation material; the upper end of the lower support (22) is welded or bolted to the lower end of the upper support (21), and the lower end is welded and fixed to the bottom plate (223); the bottom plate (223) is fixedly connected to the foundation (4) by anchor bolts (222); and a lower support ear (221) is welded to the lower support (222) near the bottom plate (223).

10. The spherical storage tank for high-temperature molten salt according to any one of claims 1 to 9, characterized in that: Adjacent pillars (2) are connected by a cross tie rod (3); the cross tie rod (3) is made of a steel pipe, one end of which is fixedly connected to the upper support ear (212) of one pillar (2), and the other end of which is fixedly connected to the lower support ear (221) of the adjacent pillar (2).

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