Molten salt storage tank device and molten salt heat storage system

Abstract

The invention relates to the technical field of fused salt heat storage, and provides a fused salt storage tank device. The heat exchange pipeline is arranged close to the tank wall of the tank body and comprises a first inlet close to the bottom of the tank body and a first outlet close to the top of the tank body; the heat transfer cylinder is arranged in the tank body and is coaxial with the tank body, the upper end and the lower end of the heat transfer cylinder are closed, and the heat transfer cylinder is arranged along the height direction of the tank body; a fused salt heat storage material is arranged in a space between the interior of the tank body and the exterior of the heat transfer cylinder; the heating device is inserted into the fused salt heat storage material in the tank body in the vertical direction and is used for heating the fused salt heat storage material; and the preheating device is provided with a water inlet and a water outlet, the water outlet communicates with the first inlet, and the preheating device is configured to preheat water through heat in the heat transfer cylinder and introduce the preheated water into the heat exchange pipeline. The use amount of the molten salt is reduced, the investment cost is reduced, and meanwhile the temperature uniformity of the molten salt is improved. The invention further provides a fused salt heat storage system.

Description

Technical Field

[0001] The present application relates to the technical field of molten salt heat storage, and in particular to a molten salt storage tank device and a molten salt heat storage system. Background Art

[0002] At present, there is a molten salt storage tank device, which includes a molten salt tank, an electric heating unit and a heat exchange pipe. The molten salt tank is filled with molten salt. The electric heating unit is inserted into the molten salt in the tank from the top of the molten salt tank. The electric heating unit is used to heat the molten salt. The heat exchange pipe includes an inlet near the bottom of the molten salt tank and an outlet near the top of the molten salt tank. When the low-temperature fluid enters the heat exchange pipe from the inlet, heat exchange occurs with the high-temperature molten salt in the tank through the heat exchange pipe, thereby converting the low-temperature fluid into a high-temperature and high-pressure fluid and discharging it from the outlet of the heat exchange pipe.

[0003] When the molten salt storage tank device is storing heat, the electric heating unit heats the molten salt to melt, and the density of the molten salt decreases as the temperature rises. The higher the temperature of the molten salt, the larger the volume and the smaller the density. As the heating process continues, the molten salt with higher temperature and lower density will rise, while the molten salt with lower temperature and higher density will sink. When the upper molten salt is heated to the highest operating temperature, the electric heating unit stops working, but at this time the temperature of the molten salt in the lower part of the tank is still relatively low, and the heat storage capacity of the molten salt in the lower part of the tank is not fully utilized, resulting in cost waste.

[0004] When the molten salt storage tank device releases heat, the water enters from the bottom and exits from the top. The heat exchange pipes are preheating section, boiling section and superheating section from bottom to top. The heat transfer coefficient, heat transfer temperature difference and heat transfer amount of the preheating section + boiling section are significantly higher than those of the superheating section. Therefore, the temperature drop rate of the molten salt in the lower part of the molten salt tank is higher than that of the upper part. The overall temperature distribution of the molten salt in the tank is characterized by being low at the bottom and high at the top. Since the heat exchange pipes are arranged around the periphery of the molten salt, the utilization rate of the molten salt (outer molten salt) close to the heat exchange pipes is higher when releasing heat, while the heat release capacity of the molten salt (inner core molten salt) far away from the heat exchange pipes is not fully utilized, resulting in cost waste. Summary of the invention

[0005] In order to solve the above problems, the present application provides a molten salt storage tank device and a molten salt heat storage system, which are cleverly designed and simple in structure. The present application reduces the amount of molten salt used, reduces the investment cost, and improves the uniformity of the molten salt temperature. At the same time, it improves the utilization rate of the molten salt far away from the heat exchange pipe (inner core molten salt or core layer molten salt). The technical solution adopted in the present application is as follows:

[0006] A molten salt storage tank device, comprising:

[0007] A tank body; a heat exchange pipe, the heat exchange pipe is arranged close to the tank wall of the tank body, the heat exchange pipe includes a first inlet close to the bottom of the tank body and a first outlet close to the top of the tank body; a heat transfer tube, the heat transfer tube is arranged in the tank body and coaxially with the tank body, the upper and lower ends of the heat transfer tube are closed, and the heat transfer tube is arranged along the height direction of the tank body; a molten salt heat storage material is arranged in the space between the tank body and the outside of the heat transfer tube; a heating device, the heating device is inserted into the molten salt heat storage material in the tank body along the vertical direction, and the heating device is used to heat the molten salt heat storage material; a preheating device, the preheating device is provided with a water inlet and a water outlet, the water outlet is connected to the first inlet, and the preheating device is configured to use the heat in the heat transfer tube to preheat the water entering through the water inlet, and pass the preheated water into the heat exchange pipe through the water outlet.

[0008] By setting up the heat transfer tube, not only the use of molten salt heat storage materials is reduced, and the investment cost is reduced, but also the heat conductivity of the heat transfer tube can be used to transfer the heat of the molten salt at a high place to the molten salt at a low place, thereby improving the temperature uniformity of the molten salt in the height direction. In addition, by setting up a preheating device, the utilization of the heat of the molten salt close to the heat transfer tube is enhanced. In addition, the water preheated by the preheating device is passed into the heat exchange pipe. Because the water has been preheated and absorbed a certain amount of heat, when the molten salt storage tank device releases heat, the heat demand for the molten salt (outer layer molten salt) close to the heat exchange pipe is reduced, thereby improving the temperature uniformity of the inner and outer layers of the molten salt.

[0009] In some embodiments, the preheating device further includes an air inlet and an air outlet. The preheating device is disposed outside the tank body, the air inlet is connected to the top of the heat transfer tube, and the air outlet is connected to the bottom of the heat transfer tube. The hot air in the heat transfer tube enters the preheating device from the air inlet and exchanges heat with the water entering from the water inlet. The water after heat exchange flows into the heat exchange pipe from the water outlet, and the hot air after heat exchange flows back into the heat transfer tube from the air outlet. Placing the preheating device outside the tank body facilitates installation and maintenance of the preheating device.

[0010] By setting an air inlet and an air outlet, and connecting the air inlet to the top of the heat transfer tube and the air outlet to the bottom of the heat transfer tube, the high-temperature hot air has a low density in the heat transfer tube and rises to the preheating device for heat exchange. After the heat exchange, the air temperature decreases and the density increases, and then flows back to the heat transfer tube from the air outlet, forming a natural circulation flow, strengthening the heat dissipation at the top of the tank body, giving priority to the use of the top heat, reducing the top temperature, and balancing the temperature difference in the height direction of the tank body.

[0011] In some embodiments, the preheating device is located on the tank top of the tank body. By placing the preheating device on the tank top of the tank body, the hot gas naturally flows to a higher place, and the molten salt with a higher temperature is close to the tank top, and the molten salt with a lower temperature is located at the tank bottom, which results in the temperature of the tank top area outside the tank body being generally higher than the temperature of other places outside the tank body. In this way, on the one hand, the preheating device can utilize the heat lost at the tank top to reduce heat loss, and on the other hand, the presence of the preheating device can have a cooling effect on the tank top area, reducing the risk of damage to components in the tank top area.

[0012] In some embodiments, a non-molten salt heat storage material is disposed in the heat transfer cylinder, and an air duct is disposed in the non-molten salt heat storage material. The air duct is disposed through the non-molten salt heat storage material in a height direction.

[0013] By setting non-molten salt heat storage materials in the heat transfer cylinder, the non-molten salt heat storage materials will also store heat when the heating device heats the molten salt heat storage materials, and the non-molten salt heat storage materials will also release heat when the molten salt heat storage materials release heat. In addition, the non-molten salt heat storage materials also play a role in strengthening the upper and lower heat conduction, which not only improves the heat storage capacity of the entire molten salt storage tank device, but also, the non-molten salt heat storage materials will not flow like the molten salt heat storage materials. The temperature difference between the upper and lower layers of the non-molten salt heat storage materials is much lower than that of the molten salt heat storage materials, which objectively enhances the heat supplement effect on the lower molten salt, while absorbing the temperature of the upper molten salt, which further improves the temperature uniformity of the molten salt in the height direction. By setting the air duct, the efficiency of gas circulation in the preheating device and the heat transfer cylinder can be ensured, thereby ensuring the heat supply of the preheating device. In addition, the setting of the air duct enables the non-molten salt heat storage materials to conduct heat convection through the air duct in addition to direct contact heat transfer, thereby improving the temperature uniformity of the non-molten salt heat storage materials and ensuring the utilization rate of the heat storage capacity of the non-molten salt heat storage materials.

[0014] In some embodiments, the preheating device is disposed in the heat transfer cylinder and close to the top of the tank body.

[0015] By placing the preheating device in the heat transfer cylinder and close to the top of the tank, the hot gas naturally flows to the top, and the higher temperature molten salt is close to the top of the tank, while the lower temperature molten salt is located at the bottom of the tank. This results in the temperature of the tank top area in the tank being generally higher than the temperature of other places in the tank. This ensures that the preheating device has a higher heat exchange efficiency on the one hand, and on the other hand, the presence of the preheating device can reduce the temperature of the tank top area, reducing the risk of damage to components in the tank top area. In addition, the preheating device can also use the heat of the molten salt at a high place to reduce the temperature difference between the molten salt at a high place and the molten salt at a low place, thereby improving the temperature uniformity of the molten salt in the height direction.

[0016] In some embodiments, a non-molten salt heat storage material is disposed in the heat transfer cylinder, and the preheating device is placed on the non-molten salt heat storage material.

[0017] By arranging non-molten salt heat storage materials in the heat transfer cylinder, the non-molten salt heat storage materials will also store heat when the heating device heats the molten salt heat storage materials, and will also release heat when the molten salt heat storage materials release heat. In addition, the non-molten salt heat storage materials also play a role in enhancing the upper and lower heat conduction, which not only improves the heat storage capacity of the entire molten salt storage tank device, but also, the non-molten salt heat storage materials will not flow like the molten salt heat storage materials. The temperature difference between the upper and lower layers of the non-molten salt heat storage materials is much lower than that of the molten salt heat storage materials, which objectively enhances the heat supplement effect on the lower molten salt, while absorbing the upper molten salt temperature, which improves the temperature uniformity of the molten salt in the height direction.

[0018] In some embodiments, the preheating device is a heat exchange coil.

[0019] In some embodiments, the preheating device is a preheating water tank, and a baffle is provided in the preheating water tank. By providing the baffle, the flow path of water in the preheating water tank is extended, and the heat exchange efficiency of the preheating water tank is improved.

[0020] In some embodiments, a plurality of heat-conducting fins are provided around the outer circumference of the heat transfer tube.

[0021] By arranging heat-conducting fins outside the heat transfer tube, the heat-conducting fins are immersed in the molten salt heat storage material, and the heat-conducting fins and the heat transfer tube form a whole, which increases the heat transfer area compared to the heat transfer tube without heat-conducting fins, which is not only conducive to quickly transferring the heat of the molten salt heat storage material at a high position to the molten salt heat storage material at a low position, but also improves the temperature uniformity of the molten salt in the height direction. At the same time, when non-molten salt heat storage materials are arranged in the heat transfer tube, it is also conducive to quickly transferring the heat of the non-molten salt heat storage material to the molten salt heat storage material, thereby improving the thermal conductivity efficiency.

[0022] On the other hand, the present application provides a molten salt heat storage system, which adopts the aforementioned molten salt storage tank device.

[0023] The present application provides a molten salt storage tank device and a molten salt heat storage system, which has at least one of the following beneficial effects:

[0024] 1. The present application provides a molten salt storage tank device, which not only reduces the use of molten salt heat storage materials and reduces investment costs by setting a heat transfer tube, but also utilizes the thermal conductivity of the heat transfer tube to transfer the heat of the molten salt at a high place to the molten salt at a low place, thereby improving the temperature uniformity of the molten salt in the height direction. In addition, by setting a preheating device, the utilization of the heat of the molten salt close to the heat transfer tube is enhanced. In addition, the water preheated by the preheating device is passed into the heat exchange pipe. Because the water has been preheated and absorbed a certain amount of heat, when the molten salt storage tank device releases heat, the heat demand for the molten salt (outer molten salt) close to the heat exchange pipe is reduced, thereby improving the temperature uniformity of the inner and outer molten salts.

[0025] 2. The present application provides a molten salt storage tank device, which facilitates the installation and maintenance of the preheating device by placing the preheating device outside the tank body.

[0026] 3. The present application provides a molten salt storage tank device, which places a preheating device on the top of the tank body, and the hot gas naturally flows to a higher place, and the molten salt with a higher temperature is close to the top of the tank, and the molten salt with a lower temperature is located at the bottom of the tank. This causes the temperature of the top area outside the tank to be generally higher than the temperature of other places outside the tank. In this way, on the one hand, the preheating device can utilize the heat lost at the top of the tank to reduce heat loss. On the other hand, the presence of the preheating device can have a cooling effect on the top area of ​​the tank, reducing the risk of damage to components in the top area of ​​the tank.

[0027] 4. The present application provides a molten salt storage tank device, which arranges non-molten salt heat storage materials in the heat transfer cylinder. When the heating device heats the molten salt heat storage materials, the non-molten salt heat storage materials will also store heat, and when the molten salt heat storage materials release heat, the non-molten salt heat storage materials will also release heat. In addition, the non-molten salt heat storage materials also play a role in strengthening the upper and lower heat conduction, which not only improves the heat storage capacity of the entire molten salt storage tank device, but also, the non-molten salt heat storage materials will not flow like the molten salt heat storage materials. The temperature difference between the upper and lower layers of the non-molten salt heat storage materials is much lower than that of the molten salt heat storage materials, which objectively enhances the heat supplement effect on the lower molten salt, while absorbing the temperature of the upper molten salt, which further improves the temperature uniformity of the molten salt in the height direction. By setting up the air duct, the efficiency of gas circulation in the preheating device and the heat transfer cylinder can be ensured, thereby ensuring the heat supply of the preheating device. In addition, the setting of the air duct enables heat convection between non-molten salt heat storage materials in addition to direct contact heat transfer, thereby improving the temperature uniformity of the non-molten salt heat storage materials and ensuring the utilization of the heat storage capacity of the non-molten salt heat storage materials.

[0028] 5. The present application provides a molten salt storage tank device, which is provided with a preheating device in a heat transfer cylinder near the top of the tank body, and the hot gas naturally flows to a higher place, and the molten salt with a higher temperature is close to the top of the tank, and the molten salt with a lower temperature is located at the bottom of the tank, which results in the temperature of the tank top area in the tank body being generally higher than the temperature of other places in the tank body. In this way, on the one hand, it can ensure that the preheating device has a higher heat exchange efficiency, and on the other hand, the presence of the preheating device can reduce the temperature of the tank top area, reducing the risk of damage to components in the tank top area. In addition, the preheating device can also use the heat of the molten salt at a high place to reduce the temperature difference between the molten salt at a high place and the molten salt at a low place, and improve the temperature uniformity of the molten salt in the height direction.

[0029] 6. The present application provides a molten salt storage tank device, in which a non-molten salt heat storage material is arranged in a heat transfer cylinder. When the heating device heats the molten salt heat storage material, the non-molten salt heat storage material will also store heat, and when the molten salt heat storage material releases heat, the non-molten salt heat storage material will also release heat. In addition, the non-molten salt heat storage material also plays a role in enhancing the upper and lower heat conduction, which not only improves the heat storage capacity of the entire molten salt storage tank device, but also, the non-molten salt heat storage material will not flow like the molten salt heat storage material. The temperature difference between the upper and lower layers of the non-molten salt heat storage material is much lower than that of the molten salt heat storage material, which objectively enhances the heat supplement effect on the lower molten salt, while absorbing the upper molten salt temperature, which improves the temperature uniformity of the molten salt in the height direction.

[0030] 7. The molten salt storage tank device provided in the present application prolongs the flow path of water in the preheating water tank by setting a baffle, thereby improving the heat exchange efficiency of the preheating water tank.

[0031] 8. The present application provides a molten salt storage tank device, which increases the heat transfer area by arranging heat-conducting fins outside the heat transfer cylinder, and immersing the heat-conducting fins in the molten salt heat storage material. Compared with the heat transfer cylinder without heat-conducting fins, the whole formed by the heat-conducting fins and the heat transfer cylinder increases the heat transfer area, which is not only conducive to quickly transferring the heat of the molten salt heat storage material at a high position to the molten salt heat storage material at a low position, but also improves the temperature uniformity of the molten salt in the height direction. At the same time, when non-molten salt heat storage materials are arranged in the heat transfer cylinder, it is also conducive to quickly transferring the heat of the non-molten salt heat storage materials to the molten salt heat storage materials, thereby improving the heat conduction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The following will explain the preferred implementation mode in a clear and understandable manner in conjunction with the accompanying drawings to further illustrate the above characteristics, technical features, advantages and implementation methods of a molten salt storage tank device and a molten salt heat storage system:

[0033] Figure 1 It is a schematic diagram of the overall structure of an embodiment of a molten salt storage tank device in which a preheating device is placed outside the tank body;

[0034] Figure 2 is Figure 1 A schematic diagram of the overall structure of an embodiment in which a non-molten salt heat storage material is arranged in a heat transfer cylinder based on the embodiment;

[0035] Figure 3 It is a schematic diagram of the overall structure of an embodiment of a molten salt storage tank device in which a preheating device (water tank) is placed in a tank body;

[0036] Figure 4 is Figure 3 A schematic diagram of the overall structure of an embodiment in which a non-molten salt heat storage material is arranged in a heat transfer cylinder based on the embodiment;

[0037] Figure 5It is a schematic diagram of the overall structure of an embodiment of a molten salt storage tank device in which a baffle is arranged in a preheating device (water tank);

[0038] Figure 6 It is a schematic diagram of the overall structure of an embodiment of a molten salt storage tank device in which a preheating device (heat exchange coil) is placed in the tank body.

[0039] Description of Figure Numbers:

[0040] Tank body 1, heat transfer tube 2, heating device 3, preheating device 4, air inlet end 5, air outlet end 6, non-molten salt heat storage material 7, air duct 8, baffle 9, heat conduction fins 10. DETAILED DESCRIPTION

[0041] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the specific implementation methods of the present application will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work.

[0042] In order to simplify the drawings, only the parts related to the present application are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0043] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0044] In this document, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0045] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0046] refer to Figure 1-Figure 6The present application provides a molten salt storage tank device, comprising: a tank body 1; a heat exchange pipe, which is arranged near the tank wall of the tank body 1, and the heat exchange pipe comprises a first inlet near the bottom of the tank body 1 and a first outlet near the top of the tank body 1; a heat transfer tube 2, which is arranged in the tank body 1 and coaxially with the tank body 1, the upper and lower ends of the heat transfer tube 2 are closed, and the heat transfer tube 2 is arranged along the height direction of the tank body 1; a molten salt heat storage material is arranged in the space between the tank body 1 and the outside of the heat transfer tube 2; a heating device 3, which is inserted into the molten salt heat storage material in the tank body 1 in a vertical direction, and the heating device 3 is used to heat the molten salt heat storage material; a preheating device 4, which is provided with a water inlet and a water outlet, and the water outlet is connected to the first inlet, and the preheating device 4 is configured to use the heat in the heat transfer tube 2 to preheat the water entering from the water inlet, and pass the preheated water into the heat exchange pipe from the water outlet.

[0047] It should be noted that the molten salt heat storage material mentioned in this application is referred to as molten salt, that is, the molten salt heat storage material and molten salt mentioned below refer to the same substance. The heat transfer tube 2 can be made of metal material only, or a heat conductive coating is provided on the surface of the metal material. The heat conductive coating can be graphene, high temperature resistant heat conductive coating, etc. The heat transfer tube 2 can also be made of other heat conductive materials.

[0048] It is understandable that by providing the heat transfer tube 2, not only the amount of molten salt heat storage material used is reduced, the investment cost is reduced, but also the heat conductivity of the heat transfer tube 2 can be used to transfer the heat of the molten salt at a high position to the molten salt at a low position, thereby improving the temperature uniformity of the molten salt in the height direction. In addition, by providing the preheating device 4, the utilization of the heat of the molten salt near the heat transfer tube 2 is enhanced. In addition, the water preheated by the preheating device 4 is passed into the heat exchange pipe. Because the water has been preheated and has absorbed a certain amount of heat, when the molten salt storage tank device releases heat, the heat demand for the molten salt (outer layer molten salt) near the heat exchange pipe is reduced, thereby improving the temperature uniformity of the inner and outer layers of the molten salt.

[0049] refer to Figure 1 , Figure 2 In one embodiment, the preheating device 4 further includes an air inlet 5 and an air outlet 6. The preheating device 4 is arranged outside the tank body 1. The air inlet 5 is connected to the top of the heat transfer tube 2, and the air outlet 6 is connected to the bottom of the heat transfer tube 2. The hot air in the heat transfer tube 2 enters the preheating device 4 from the air inlet 5 and exchanges heat with the water entering from the water inlet. The water after heat exchange flows into the heat exchange pipe from the water outlet, and the hot air after heat exchange flows back into the heat transfer tube 2 from the air outlet 6. By placing the preheating device 4 outside the tank body 1, the installation and maintenance of the preheating device 4 are facilitated.

[0050] Specifically, in this embodiment, the preheating device 4 is a wind-water heat exchanger, which is provided with a water inlet, a water outlet, an air inlet end 5 and an air outlet end 6. The hot air in the heat transfer tube 2 enters from the air inlet end 5 and is discharged from the air outlet end 6. The gas discharged from the air outlet end 6 flows back into the heat transfer tube 2 from the bottom of the heat transfer tube 2 through the air circulation loop. The water to be preheated enters from the water inlet of the wind-water heat exchanger and is discharged from the water outlet. The water to be preheated is preheated by the hot air in the heat transfer tube 2. It can be understood that the specific structure of the wind-water heat exchanger is a prior art and will not be described in detail here.

[0051] By setting an air inlet and an air outlet, and connecting the air inlet to the top of the heat transfer tube and the air outlet to the bottom of the heat transfer tube, the high-temperature hot air has a low density in the heat transfer tube and rises to the preheating device for heat exchange. After the heat exchange, the air temperature decreases and the density increases, and then flows back to the heat transfer tube from the air outlet, forming a natural circulation flow, strengthening the heat dissipation at the top of the tank body, giving priority to the use of the top heat, reducing the top temperature, and balancing the temperature difference in the height direction of the tank body.

[0052] refer to Figure 1 , Figure 2 In one embodiment, the preheating device 4 is located on the tank top of the tank body 1. It is easy to understand that the hot air in the tank body 1 and the heat transfer tube 2 naturally flows from the lower part to the higher part, and the molten salt with higher temperature is close to the tank top, and the molten salt with lower temperature is located at the tank bottom, which results in that the temperature of the tank top area outside the tank body 1 is generally higher than the temperature of other places outside the tank body 1. By placing the preheating device 4 on the tank top of the tank body 1, on the one hand, the preheating device 4 can utilize the heat lost at the tank top to reduce heat loss, and on the other hand, the presence of the preheating device 4 can reduce the temperature of the tank top area, reducing the risk of damage to components in the tank top area.

[0053] refer to Figure 2 In one embodiment, a non-molten salt heat storage material 7 is provided in the heat transfer tube 2 , and an air duct 8 is provided in the non-molten salt heat storage material 7 . The air duct 8 is provided through the non-molten salt heat storage material 7 in a height direction.

[0054] Specifically, the non-molten salt heat storage material 7 has a lower volume cost than the molten salt heat storage material, and the non-molten salt heat storage material 7 is solid. The non-molten salt heat storage material 7 will not melt after heat storage. Compared with the molten salt heat storage material, it will not flow, and the heat release is slower than the molten salt heat storage material. The molten salt heat storage material mentioned in this application can be a molten salt formed by mixing 50% sodium nitrate and 50% potassium nitrate, or a molten salt formed by mixing 60% sodium nitrate and 40% potassium nitrate, or a low melting point molten salt (melting point as low as about 80°) disclosed in the patent with application number CN201911219662, or a multi-component mixed molten salt (melting point as low as 47.3°) disclosed in the patent with application number CN202311105206, or other types of molten salts. It can be understood that the molten salt heat storage material can be composed of one molten salt or a mixture of multiple molten salts. The non-molten salt heat storage material 7 is a solid heat storage medium, which can be ceramsite, metal block, corundum block, high aluminum block, dolomite block, ore, glass, gravel, sand, etc. It should be noted that the non-molten salt heat storage material 7 can also be heat storage bricks and concrete. The non-molten salt heat storage material 7 can also be a combination of one or more of the above example materials.

[0055] In this embodiment, there are many ways to form the air duct 8. For example, when the non-molten salt heat storage material 7 is not densely filled, there are gaps between the non-molten salt heat storage materials 7, and the gaps can form the air duct 8; when the non-molten salt heat storage material 7 is set by masonry, the gaps between the blocks (made of the non-molten salt heat storage material 7) can also form the air duct 8. When the non-molten salt heat storage material 7 is set by masonry, the gaps between the blocks (made of the non-molten salt heat storage material 7) can also form the air duct 8. The size of the air duct 8 can be adjusted by adjusting the size of the gaps between the blocks during masonry. In addition, the air duct 8 can also be formed by reserving when the non-molten salt heat storage material 7 is set, that is, the non-molten salt heat storage material 7 in the heat transfer cylinder 2 can be set to a hollow shape, and the hollow space in the non-molten salt heat storage material 7 forms the air duct 8.

[0056] It is worth noting that by arranging the non-molten salt heat storage material 7 in the heat transfer tube 2, the non-molten salt heat storage material 7 will also store heat when the heating device 3 heats the molten salt heat storage material, and the non-molten salt heat storage material 7 will also release heat when the molten salt heat storage material releases heat. In addition, the non-molten salt heat storage material 7 also plays a role in strengthening the upper and lower heat conduction, which not only improves the heat storage capacity of the entire molten salt storage tank device, but also, the non-molten salt heat storage material 7 will not flow like the molten salt heat storage material, and the temperature difference between the upper and lower layers of the non-molten salt heat storage material 7 is much lower than that of the molten salt heat storage material, which objectively enhances the heat supplement effect on the lower molten salt, while absorbing the temperature of the upper molten salt, which further improves the temperature uniformity of the molten salt in the height direction. By setting the air duct 8, the efficiency of gas circulation in the preheating device 4 and the heat transfer tube 2 can be ensured, thereby ensuring the heat supply of the preheating device 4. In addition, the setting of the air duct 8 allows the non-molten salt heat storage materials 7 to conduct heat convection through the air duct 8 in addition to direct contact heat transfer, thereby improving the temperature uniformity of the non-molten salt heat storage materials 7 and ensuring the utilization rate of the heat storage capacity of the non-molten salt heat storage materials 7.

[0057] refer to Figure 3-Figure 6 In one embodiment, the preheating device 4 is disposed in the heat transfer tube 2 and close to the top of the tank body 1.

[0058] Specifically, in this embodiment, the preheating device 4 can be a water tank structure (such as Figure 3-Figure 5 Example), heat exchange coil structure (such as Figure 6 For example, various heat exchanger structures or steam drum structures for generating steam, when the preheating device 4 is a water tank structure (preheating water tank), it is preferred to set a baffle 9 in the water tank structure (such as Figure 5 For example, by setting the baffle 9, the flow path of the water in the preheating water tank is extended, and the heat exchange efficiency of the preheating water tank is improved. When the preheating device 4 is a heat exchange coil, the specific form of the heat exchange coil can be a spiral coil, a serpentine coil (such as Figure 6 example) or other shapes.

[0059] It is easy to understand that the hot air in the tank body 1 and the heat transfer tube 2 flows naturally from the lower part to the higher part, and the molten salt with a higher temperature is close to the tank top, while the molten salt with a lower temperature is at the bottom of the tank, which results in the temperature of the tank top area in the tank body 1 being generally higher than the temperature of other places in the tank body 1. By arranging the preheating device 4 in the heat transfer tube 2 and close to the top of the tank body 1, on the one hand, it can ensure that the preheating device 4 has a higher heat exchange efficiency, and on the other hand, the presence of the preheating device 4 can reduce the temperature of the tank top area and reduce the risk of damage to components in the tank top area. In addition, the preheating device 4 can also use the heat of the molten salt at a high place to reduce the temperature difference between the molten salt at a high place and the molten salt at a low place, thereby improving the temperature uniformity of the molten salt in the height direction.

[0060] refer to Figure 4-Figure 6In one embodiment, a non-molten salt heat storage material 7 is provided in the heat transfer cylinder 2 , and the preheating device 4 is placed on the non-molten salt heat storage material 7 .

[0061] Specifically, the non-molten salt heat storage material 7 in this embodiment has been introduced in the previous text. Please refer to the previous text for the specific content, which will not be repeated here. By arranging the non-molten salt heat storage material 7 in the heat transfer tube 2, the non-molten salt heat storage material 7 will also store heat when the heating device 3 heats the molten salt heat storage material, and the non-molten salt heat storage material 7 will also release heat when the molten salt heat storage material releases heat. In addition, the non-molten salt heat storage material 7 also plays a role in strengthening the upper and lower heat conduction, which not only improves the heat storage capacity of the entire molten salt storage tank device, but also, the non-molten salt heat storage material 7 will not flow like the molten salt heat storage material. The temperature difference between the upper and lower layers of the non-molten salt heat storage material 7 is much lower than that of the molten salt heat storage material, which objectively enhances the heat supplement effect on the lower molten salt, while absorbing the temperature of the upper molten salt, which improves the temperature uniformity of the molten salt in the height direction.

[0062] refer to Figure 1-Figure 6 In one embodiment, a plurality of heat-conducting fins 10 are provided around the outer circumference of the heat transfer tube 2 .

[0063] It should be noted that by arranging heat-conducting fins 10 outside the heat transfer tube 2, the heat-conducting fins 10 are immersed in the molten salt heat storage material, and the heat-conducting fins 10 and the heat transfer tube 2 form a whole, which increases the heat transfer area compared to the heat transfer tube 2 without the heat-conducting fins 10, which is not only conducive to quickly transferring the heat of the molten salt heat storage material at a high position to the molten salt heat storage material at a low position, but also improves the temperature uniformity of the molten salt in the height direction. At the same time, when the non-molten salt heat storage material 7 is arranged in the heat transfer tube 2, it is also conducive to quickly transferring the heat of the non-molten salt heat storage material 7 to the molten salt heat storage material, thereby improving the heat conduction efficiency.

[0064] On the other hand, the present application provides a molten salt heat storage system, which adopts the aforementioned molten salt storage tank device. The specific structure of the molten salt storage tank device refers to the aforementioned embodiment. Since the present molten salt heat storage system adopts the technical solution of the aforementioned embodiment, it at least has the beneficial effects brought by the technical solution of the aforementioned embodiment, which will not be repeated here one by one.

[0065] It should be noted that the above embodiments can be freely combined as needed. The above are only preferred implementations of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A molten salt storage tank device, characterized in that: include: Tank; A heat exchange pipe, the heat exchange pipe is arranged close to the tank wall of the tank body, and the heat exchange pipe includes a first inlet close to the bottom of the tank body and a first outlet close to the top of the tank body; A heat transfer tube, which is disposed in the tank body and coaxially arranged with the tank body, the upper and lower ends of the heat transfer tube are closed, and the heat transfer tube is arranged along the height direction of the tank body; a molten salt heat storage material is arranged in the space between the tank body and the outside of the heat transfer tube; A heating device, the heating device is inserted into the molten salt heat storage material in the tank body along a vertical direction, and the heating device is used to heat the molten salt heat storage material; A preheating device, wherein the preheating device is provided with a water inlet and a water outlet, wherein the water outlet is connected to the first inlet, and the preheating device is configured to utilize the heat in the heat transfer cylinder to preheat the water entering through the water inlet, and to pass the preheated water through the water outlet into the heat exchange pipe.

2. A molten salt storage tank device according to claim 1, characterized in that: The preheating device also includes an air inlet and an air outlet. The preheating device is arranged outside the tank body. The air inlet is connected to the top of the heat transfer tube, and the air outlet is connected to the bottom of the heat transfer tube. The hot air in the heat transfer tube enters the preheating device from the air inlet and exchanges heat with the water entering from the water inlet. The water after heat exchange flows into the heat exchange pipe from the water outlet, and the hot air after heat exchange flows back into the heat transfer tube from the air outlet.

3. A molten salt storage tank device according to claim 2, characterized in that: The preheating device is located on the tank top of the tank body.

4. A molten salt storage tank device according to claim 3, characterized in that: A non-molten salt heat storage material is arranged in the heat transfer cylinder, and an air duct is arranged in the non-molten salt heat storage material. The air duct is arranged to penetrate along the height direction of the non-molten salt heat storage material.

5. A molten salt storage tank device according to claim 1, characterized in that: The preheating device is arranged in the heat transfer cylinder and close to the top of the tank body.

6. A molten salt storage tank device according to claim 5, characterized in that: A non-molten salt heat storage material is arranged in the heat transfer cylinder, and the preheating device is placed on the non-molten salt heat storage material.

7. A molten salt storage tank device according to claim 6, characterized in that: The preheating device is a heat exchange coil. (Figure 6) 8. A molten salt storage tank device according to claim 1, characterized in that: The preheating device is a preheating water tank, and a baffle is arranged in the preheating water tank.

9. A molten salt storage tank device according to any one of claims 1 to 8, characterized in that: A plurality of heat-conducting fins are arranged in an circumferential direction on the outer circumference of the heat transfer cylinder.

10. A molten salt heat storage system, characterized in that: A molten salt storage tank device according to any one of claims 1 to 9 is used.

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