A molten salt storage tank system capable of saving the dead bottom molten salt inventory

Abstract

This invention discloses a molten salt storage tank system that saves on molten salt in the bottom dead zone. The system includes a molten salt storage tank body and a molten salt suction pipe. The suction pipe extends through a pump inlet to a certain height at the bottom of the tank, leaving a gap between it and the bottom. The bottom end of the suction pipe is below the molten salt surface. A pump trough is located at the bottom of the tank directly below the suction pipe. The lower section of the suction pipe covers the outside of the pump trough, and the suction inlet of the molten salt pump is placed in the pump trough, below its upper end. The upper section of the suction pipe is connected to a vacuum main pipe, on which a vacuum pump is installed. This invention uses the vacuum pump to create a negative pressure inside the suction pipe, making the external pressure greater than the internal pressure. Driven by this pressure difference, the molten salt passes through the gap between the lower end of the suction pipe and the tank bottom, entering the suction pipe and the pump trough. The pump then transports the molten salt to an external system, reducing the height of the molten salt in the bottom dead zone of the storage tank to approximately 0.2 meters, thus improving the utilization rate of the molten salt.

Description

Technical Field

[0001] This invention relates to the field of molten salt energy storage technology, specifically to a molten salt storage tank system that can save on the amount of molten salt stored in the bottom dead zone. Background Technology

[0002] Molten salt energy storage technology has been widely used in the field of solar thermal power generation. Currently, the mainstream technology is the dual-tank technology, namely, high-temperature molten salt tank and low-temperature molten salt tank technology. During the energy storage process, the high-temperature molten salt, after absorbing heat energy, is stored in the high-temperature molten salt tank. During the energy release process, the high-temperature molten salt in the high-temperature molten salt tank releases heat energy through a heat exchanger, and after its temperature decreases, it becomes low-temperature molten salt, which is then stored in the low-temperature molten salt tank. High-temperature molten salt tanks and low-temperature molten salt tanks are collectively referred to as molten salt tanks.

[0003] Traditional molten salt storage tanks and systems suffer from several drawbacks. The molten salt pump is directly installed at the inlet, with the pump suction port approximately 0.8 meters from the bottom of the tank. This means the molten salt below the bottom 0.8 meters cannot be effectively utilized during operation. The larger the tank, the more unusable molten salt remains in the dead zone at the bottom, resulting in higher investment costs. For example, a 33-meter diameter molten salt tank typically has approximately 1000 tons of unusable molten salt at the bottom, leading to wasted resources.

[0004] Patent CN116242185A discloses a molten salt storage tank for a low-level liquid zone in a solar thermal power plant, comprising: a tank body, a filling layer, a low-level liquid zone, and a molten salt pump; the filling layer is disposed on the bottom plate of the tank body; the low-level liquid zone is embedded in the filling layer and communicates with the interior of the tank body; the suction pump shaft of the molten salt pump passes through the top and interior of the tank body sequentially and penetrates into the low-level liquid zone. This invention utilizes the characteristic of molten salt sinking due to gravity by setting a low-level liquid zone on the bottom plate of the molten salt storage system. The liquid molten salt in the tank body will first converge towards the low-level liquid zone, and only after the low-level liquid zone is full will the liquid level in the tank body gradually rise; since the suction pump shaft of the molten salt pump is located within the low-level liquid zone, it can deliver most or even all of the liquid molten salt. However, this patent has the following limitations: First, the addition of a filling layer increases the load on the bottom of the tank, affecting the safety of the tank bottom; second, it has high requirements for the material of the filling layer, the density of the filling layer must be greater than that of molten salt and the structure must be stable. It must not crack, pulverize, deteriorate or drift during its service life, otherwise it will contaminate the molten salt and cause safety hazards to the molten salt pump and molten salt storage tank.

[0005] Patent CN121612105B discloses a "Low-position Short-shaft Pump Salt Delivery System and Method for Molten Salt Storage Tanks," comprising: a main molten salt storage tank and a molten salt discharge pipe equipped with a check valve and a shut-off valve; the top of the main molten salt storage tank is connected to an vent pipe; it also includes a molten salt pressure storage tank and a gas supply assembly; the inlet of the molten salt pressure storage tank is connected to the outlet of the main molten salt storage tank; the gas supply assembly includes an inlet pipeline, an exhaust pipeline, gas inlet and outlet pipelines, and a gas source device; the inlet pipeline, exhaust pipeline, and gas inlet and outlet pipelines are connected by a three-way switching valve; the gas source device is connected to the inlet pipeline; one end of the exhaust pipeline is connected to the main molten salt storage tank; the inlet of the molten salt atmospheric pressure storage tank is connected to the outlet of the molten salt pressure storage tank; a short-shaft pump and an vent pipe are installed on the top of the molten salt atmospheric pressure storage tank. This invention can improve the utilization rate of molten salt, enhance the operational stability and safety of the pump and molten salt system, and reduce the investment cost of the project. This patent can effectively solve the problem of long-shaft pumps and reduce the dead zone of molten salt at the bottom of the molten salt storage tank. However, the pressure control of the molten salt pressure storage tank is complicated, and the sealing between the molten salt atmospheric pressure storage tank and the short-shaft pump is difficult. If the system fails, there is a risk that molten salt will leak out from the short-shaft pump interface. At present, there are no engineering application cases for this patent. Summary of the Invention

[0006] The purpose of this invention is to provide a molten salt storage tank system that can save on the amount of molten salt in the bottom dead zone. By using a vacuum pump to create a negative pressure inside the molten salt suction pipe, the external pressure of the molten salt suction pipe is greater than the internal pressure. Driven by the pressure difference, the molten salt enters the molten salt suction pipe and pump tank through the gap between the lower end of the molten salt suction pipe and the bottom of the tank. The molten salt pump continuously delivers the molten salt to the external system, reducing the height of the molten salt in the bottom dead zone of the molten salt storage tank to about 0.2 meters, thereby improving the utilization rate of molten salt.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A molten salt storage tank system that saves molten salt in the bottom dead zone includes a molten salt storage tank body and an arc-shaped tank top. A vertically upward pump port is installed on the tank top. A molten salt suction pipe extends through the pump port to above the tank bottom. The bottom end of the molten salt suction pipe is located below the molten salt surface, leaving a gap between it and the tank bottom. The outer side wall of the upper section of the molten salt suction pipe is connected to the top of the pump port through a molten salt pump port flange. The lower section of the molten salt suction pipe covers the outside of a pump trough fixed to the tank bottom. A molten salt pump is installed inside the molten salt suction pipe. The suction port of the molten salt pump is located in the pump trough, and the bottom end of the suction port is lower than the upper end face of the pump trough cylinder. The outlet of the molten salt pump is connected to a molten salt delivery pipeline. The upper section of the molten salt suction pipe has a vacuum port and a balance port on the side wall above the flange of the molten salt pump. The vacuum port is connected to the vacuum main pipe through a vacuum branch pipe. A vacuum pump is installed on the vacuum main pipe. One end of the vacuum main pipe is connected to the gas phase space at the top of the tank, and the other end of the vacuum main pipe is sealed. The balance port is connected to the balance main pipe through a balance branch pipe. One end of the balance main pipe is connected to the gas phase space at the top of the tank, and the other end is sealed.

[0008] Preferably, the molten salt suction pipe comprises an upper section, a middle section, and a lower section connected from top to bottom. The diameter of the upper section is smaller than that of the lower section, and the middle section is a tapered tube with a smaller diameter at the top and a larger diameter at the bottom. The bottom end face of the lower section is supported on the horizontal edges of several limiting support plates welded to the bottom of the tank. The limiting support plates are L-shaped, and the outer wall of the lower section is in contact with the vertical edge of the limiting support plate.

[0009] Preferably, the pump trough includes a bottom plate and a cylinder welded perpendicularly to each other. The cylinder is coaxial with the molten salt suction pipe. The bottom plate is fixed to the bottom of the tank by several pump trough fixing supports by bolts. The pump trough fixing supports are welded to the bottom of the tank.

[0010] Preferably, the pump trough fixing support includes a horizontal pressure plate and a vertical plate that are perpendicular to each other. The pressure plate is bolted to the base plate, and a stiffening plate is installed between the pressure plate and the vertical plate.

[0011] Preferably, the molten salt suction pipe is connected and sealed to the pump port through a molten salt pump port flange, a limiting flange, a sealing gland, studs, and nuts. The upper surface of the limiting flange has a concave annular groove. The limiting flange is connected to the sealing gland by bolts. The lower surface of the sealing gland has a boss sealing surface that matches the concave annular groove. A sealing ring and sealing packing are placed between the concave annular groove and the boss sealing surface, with the sealing ring at the bottom and the sealing packing at the top.

[0012] Preferably, the limiting flange and the sealing gland have a circular hole in the middle, and the diameter of the circular hole is larger than the outer diameter of the molten salt suction pipe; the sealing ring has a circular structure, the inner diameter of which is slightly larger than the outer diameter of the molten salt suction pipe, and the outer diameter of which is slightly smaller than the diameter of the concave annular groove of the limiting flange.

[0013] Preferably, the vacuum main pipe is equipped with a branch vent valve. When the molten salt storage tank is nitrogen-sealed, the vent valve is normally closed, and when the molten salt storage tank is not nitrogen-sealed, the vent valve is normally open.

[0014] Preferably, a balance pipe shut-off valve is installed on the main balance pipe. The balance pipe shut-off valve opens when salt is introduced into the molten salt storage tank and closes when the molten salt pump pumps salt out.

[0015] Preferably, a level gauge is installed at the top of the molten salt suction pipe.

[0016] This invention uses a molten salt suction pipe that extends a certain distance above the bottom of the tank, covering the outside of the pump trough. The upper end of the pump trough's cylinder is higher than the molten salt pump's inlet. Activating a vacuum pump creates negative pressure inside the molten salt suction pipe, making the external pressure greater than the internal pressure. Driven by this pressure difference, the molten salt flows through the gap between the lower end of the suction pipe and the tank bottom into the suction pipe and the pump trough. The molten salt is then continuously transported to an external system by the molten salt pump. This reduces the height of the molten salt in the dead zone at the bottom of the molten salt storage tank to approximately 0.2 meters, significantly improving the utilization rate of the molten salt and reducing investment in molten salt production.

[0017] In this invention, the lower end of the molten salt suction pipe is fixed to the bottom of the tank by a limiting support plate. The limiting support plate is not welded to the lower section of the molten salt suction pipe. The limiting support plate is L-shaped, and the bottom end face of the lower section is supported on the horizontal edge of the limiting support plate. The outer wall of the lower section is in contact with the vertical edge of the limiting support plate, which serves as a limiting function. At the same time, it can ensure that the molten salt suction pipe has a relatively independent degree of freedom and is not constrained by the bottom of the molten salt storage tank during the entire thermal strain and settling process.

[0018] The present invention provides a pump trough at the bottom of the molten salt suction pipe. The suction port of the molten salt pump is lower than the upper end of the pump trough cylinder. During operation, when the liquid level of the molten salt storage tank is at its lowest, the molten salt in the pump trough still maintains a certain height of liquid level, which can ensure that the suction port of the molten salt pump is completely submerged in the molten salt and avoid the molten salt pump running dry.

[0019] In this invention, the pump trough is securely fixed to the bottom of the tank by a pump trough fixing support and bolts, which can effectively release the asynchronous settlement and thermal strain between the bottom of the tank and the pump trough, and ensure the safety and reliability of the molten salt storage tank.

[0020] In this invention, the molten salt pump inlet and the molten salt suction pipe are connected and sealed by a molten salt pump inlet flange, a limiting flange, and a sealing gland. A sealing ring and sealing packing are installed in the concave annular groove of the limiting flange. The sealing gland is tightened by bolts, and the compressive force is transmitted to the sealing packing, causing the sealing packing to deform. This achieves a sealing effect on the connection gap between the molten salt pump inlet and the side wall of the molten salt suction pipe. This sealing structure is a movable sealing structure. Under thermal strain, the molten salt suction pipe and the molten salt pump inlet can be relatively displaced in the horizontal and vertical directions, which can effectively release thermal expansion and vertical settlement while ensuring the sealing effect.

[0021] The working process of this invention is as follows: During the salt extraction operation, when the molten salt level in the molten salt storage tank approaches the height of the molten salt pump inlet, the level gauge sends a molten salt level signal back to the control system. The control system then activates the vacuum pump and closes the balance pipe shut-off valve, creating a negative pressure environment within the molten salt suction pipe. Driven by the pressure difference, the molten salt flows through the gap between the lower end of the suction pipe and the bottom of the tank, filling the pump tank. The molten salt pump continuously delivers the molten salt to downstream units. The level gauge monitors the molten salt level in the storage tank in real time. When the molten salt level reaches the set minimum threshold, the control system shuts off the vacuum pump and the molten salt pump, and opens the balance pipe shut-off valve, completing the salt extraction process. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the main structure of the present invention; Figure 2 yes Figure 1 Right view of the present invention; Figure 3 yes Figure 1 Schematic diagram of the molten salt suction pipe structure; Figure 4 yes Figure 3 Enlarged view of the installation structure of the middle limit flange; Figure 5 yes Figure 4 Schematic diagram of the middle limiting flange structure; Figure 6 yes Figure 4 Schematic diagram of the middle sealing gland structure; Figure 7 yes Figure 1 Schematic diagram of the pump tank structure; Figure 8 yes Figure 1 Schematic diagram of the fixed support structure for the intermediate pump tank; Figure 9 yes Figure 8 Left view of the pump tank fixed support; In the diagram: 1. Molten salt storage tank; 2. Molten salt pump inlet; 3. Molten salt pump inlet flange; 4. Molten salt suction pipe; 5. Molten salt pump; 6. Level gauge; 7. Vacuum branch pipe; 8. Vacuum pump; 9. Vent valve; 10. Vacuum main pipe; 11. Balance pipe main pipe; 12. Balance pipe shut-off valve; 13. Balance pipe branch pipe; 14. Pump tank; 15. Pump tank fixed support; 16. Molten salt pump outlet main pipe; 17. Molten salt pump outlet pipe; 18. Molten salt storage tank bottom; 19. Limiting support plate; 20. Lower section. 1. Middle section; 22. Upper section; 23. Tank top; 24. Limiting flange; 25. Molten salt suction pipe flange; 26. Vacuum port; 27. Balance port; 28. Nut; 29. ​​Gasket; 30. Stud; 31. Sealing gland; 32. Stud; 33. Nut; 34. Sealing packing; 35. Sealing ring; 36. Bolt hole; 37. Boss sealing surface; 38. Threaded hole; 39. Concave annular groove; 40. Bottom plate; 41. Bolt; 42. Cylinder; 43. Vertical plate; 44. Pressure plate; 45. Rib plate. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings.

[0024] like Figures 1 to 9 The molten salt storage tank system shown can save molten salt in the bottom dead zone. It includes a molten salt storage tank body 1 and an arc-shaped tank top 23. A vertically upward pump port 2 is installed on the tank top 23. A molten salt suction pipe 4 extends through the pump port 2 to above the tank bottom 18. The bottom end face of the molten salt suction pipe 4 is located below the molten salt surface and has a gap with the tank bottom 18. The outer side wall of the upper section 22 of the molten salt suction pipe 4 is connected to the top of the pump port 2 through a molten salt pump port flange 3. The lower section 20 of the molten salt suction pipe 4 covers the outside of the pump trough 14 fixed to the tank bottom 18. A molten salt pump 5 is installed inside the molten salt suction pipe 4. The suction port of the molten salt pump 5 is placed in the pump trough 14. The bottom end of the suction port of the molten salt pump 5 is lower than the upper end face of the cylinder 42 of the pump trough 14. The outlet of the molten salt pump 5 is connected to the molten salt conveying pipeline. The upper section 22 of the molten salt suction pipe 4 has a vacuum port 26 and a balance port 27 on the side wall above the molten salt pump port flange 3. The vacuum port 26 is connected to the vacuum main pipe 10 through the vacuum branch pipe 7. The vacuum pump 8 is installed on the vacuum main pipe 10. One end of the vacuum main pipe 10 is connected to the gas phase space of the tank top 23, and the other end of the vacuum main pipe 10 is sealed. The balance port 27 is connected to the balance main pipe 11 through the balance pipe branch pipe 13. One end of the balance main pipe 11 is connected to the gas phase space of the tank top 23, and the other end is sealed.

[0025] The molten salt suction pipe 4 consists of an upper section 22, a middle section 21, and a lower section 20 connected from top to bottom. The diameter of the upper section 22 is smaller than that of the lower section 20. The middle section 21 is a tapered pipe with a smaller top and a larger bottom. The bottom end face of the lower section 20 is supported on the horizontal edges of several limiting support plates 19 welded to the bottom of the tank 18. The limiting support plates 19 are L-shaped, and the outer wall of the lower section 20 is in contact with the vertical edge of the limiting support plates 19.

[0026] The pump tank 4 includes a bottom plate 40 and a cylinder 42 welded perpendicularly to each other. The cylinder 42 is coaxial with the molten salt suction pipe 4. The bottom plate 40 is fixed to the tank bottom 18 by several pump tank fixing supports 15 through bolts. The pump tank fixing supports 15 are welded to the tank bottom 18.

[0027] The pump tank fixed support 15 includes a horizontal pressure plate 44 and a vertical plate 43 that are perpendicular to each other. The pressure plate 44 is in contact with the base plate 40 by bolts, and a stiffening plate 45 is installed between the pressure plate 44 and the vertical plate 43.

[0028] The molten salt suction pipe 4 is connected and sealed to the pump port 2 through the molten salt pump port flange 3, the limiting flange 24, the sealing gland 31, the stud 32, and the nut 33. The upper surface of the limiting flange 24 is provided with a concave annular groove 39. The limiting flange 24 is connected to the sealing gland 31 by bolts. The lower surface of the sealing gland 31 is provided with a boss sealing surface 37 that matches the concave annular groove 39. A sealing ring 35 and a sealing packing 34 are placed between the concave annular groove 39 and the boss sealing surface 37. The sealing ring (35) is below and the sealing packing (34) is above.

[0029] The limiting flange 24 and the sealing gland 31 have a round hole in the middle, and the diameter of the round hole is larger than the outer diameter of the molten salt suction pipe 4; the sealing ring 35 is a circular ring structure, the inner diameter of which is slightly larger than the outer diameter of the molten salt suction pipe 4, and the outer diameter of which is slightly smaller than the diameter of the concave annular groove 39 of the limiting flange 24.

[0030] A branch line of the vacuum main pipe 10 is equipped with a vent valve 9. When the molten salt storage tank 1 is nitrogen-sealed, the vent valve 9 is normally closed. When the molten salt storage tank 1 is not nitrogen-sealed, the vent valve 9 is normally open.

[0031] A balance pipe shut-off valve 12 is installed on the balance pipe main pipe 11. When salt is introduced into the molten salt storage tank 1, the balance pipe shut-off valve 12 is opened. When the molten salt pump 5 pumps salt outward, the balance pipe shut-off valve 12 is closed.

[0032] A level gauge 6 is installed at the top of the molten salt suction pipe 4.

[0033] The working process of this invention is as follows: During the salt extraction operation, when the molten salt level in the molten salt storage tank 1 approaches the suction inlet height of the molten salt pump 5, the level gauge 6 feeds back the molten salt level signal to the control system. The control system then activates the vacuum pump 8 and closes the balance pipe shut-off valve 12, creating a negative pressure environment within the molten salt suction pipe 4. Driven by the pressure difference, the molten salt flows through the gap between the lower end of the suction pipe 4 and the tank bottom 18, entering the suction pipe 4 and filling the pump tank 14. The molten salt pump 5 continuously delivers the molten salt to the downstream unit. The level gauge 6 monitors the molten salt level in the tank in real time. When the molten salt level reaches the set minimum threshold, the control system shuts off the vacuum pump 8 and the molten salt pump 5, and opens the balance pipe shut-off valve 12, completing the salt extraction operation.

[0034] The above are merely preferred embodiments of the present invention. It should be noted that, for those skilled in the art, other equivalent modifications and improvements can be made based on the technical teachings provided by the present invention, and these should also be considered within the scope of protection of the present invention.

Claims

1. A molten salt storage tank system that can save molten salt storage in the bottom dead zone, comprising a molten salt storage tank body (1) and an arc-shaped tank top (23), characterized in that: A vertically upward pump port (2) is installed on the top (23) of the tank. A molten salt suction pipe (4) extends through the pump port (2) to the top of the tank bottom (18). The bottom end face of the molten salt suction pipe (4) is below the molten salt liquid surface and has a gap with the bottom (18). The outer wall of the upper section (22) of the molten salt suction pipe (4) is connected to the top of the pump port (2) through the molten salt pump port flange (3). The lower section (20) of the molten salt suction pipe (4) covers the outside of the pump trough (14) fixed to the bottom (18) of the tank. A molten salt pump (5) is installed inside the molten salt suction pipe (4). The suction port of the molten salt pump (5) is placed in the pump trough (14). The bottom end of the suction port of the molten salt pump (5) is lower than the upper end face of the cylinder (42) of the pump trough (14). The outlet of the molten salt pump (5) is connected to the molten salt conveying pipeline. The upper section (22) of the molten salt suction pipe (4) has a vacuum port (26) and a balance port (27) on the side wall above the molten salt pump port flange (3). The vacuum port (26) is connected to the vacuum main pipe (10) through the vacuum branch pipe (7). The vacuum pump (8) is installed on the vacuum main pipe (10). One end of the vacuum main pipe (10) is connected to the gas phase space of the tank top (23), and the other end of the vacuum main pipe (10) is sealed. The balance port (27) is connected to the balance main pipe (11) through the balance pipe branch pipe (13). One end of the balance main pipe (11) is connected to the gas phase space of the tank top (23), and the other end is sealed.

2. The molten salt storage tank system according to claim 1, which can save molten salt storage in the bottom dead zone, is characterized in that: The molten salt suction pipe (4) consists of an upper section (22), a middle section (21) and a lower section (20) connected from top to bottom. The diameter of the upper section (22) is smaller than that of the lower section (20). The middle section (21) is a tapered pipe with a smaller top and a larger bottom. The bottom end face of the lower section (20) is supported on the horizontal side of several limiting support plates (19) welded to the bottom of the tank (18). The limiting support plates (19) are L-shaped, and the outer wall of the lower section (20) is in contact with the vertical side of the limiting support plates (19).

3. A molten salt storage tank system according to claim 1 or 2 that can save molten salt in the bottom dead zone, characterized in that: The pump trough (4) includes a bottom plate (40) and a cylinder (42) welded perpendicularly to each other. The cylinder (42) is coaxial with the molten salt suction pipe (4). The bottom plate (40) is fixed to the bottom of the tank (18) by bolts by several pump trough fixing supports (15). The pump trough fixing supports (15) are welded to the bottom of the tank (18).

4. A molten salt storage tank system according to claim 3 that can save molten salt in the bottom dead zone, characterized in that: The pump trough fixed support (15) includes a horizontal pressure plate (44) and a vertical plate (43) that are perpendicular to each other. The pressure plate (44) is in contact with the base plate (40) by bolts. A stiffening plate (45) is installed between the pressure plate (44) and the vertical plate (43).

5. A molten salt storage tank system according to claim 1 that can save molten salt storage in the bottom dead zone, characterized in that: The molten salt suction pipe (4) is connected and sealed to the pump port (2) through the molten salt pump port flange (3), the limiting flange (24), the sealing gland (31), the stud (32), and the nut (33). The upper surface of the limiting flange (24) is provided with a concave annular groove (39). The limiting flange (24) is connected to the sealing gland (31) by bolts. The lower surface of the sealing gland (31) is provided with a boss sealing surface (37) that matches the concave annular groove (39). A sealing ring (35) and a sealing packing (34) are placed between the concave annular groove (39) and the boss sealing surface (37), with the sealing ring (35) at the bottom and the sealing packing (34) at the top.

6. A molten salt storage tank system according to claim 5 that can save molten salt in the bottom dead zone, characterized in that: The limiting flange (24) and sealing cover (31) have a round hole in the middle, and the diameter of the round hole is larger than the outer diameter of the molten salt suction pipe (4); the sealing ring (35) is a circular ring structure, and its inner diameter is slightly larger than the outer diameter of the molten salt suction pipe (4), and its outer diameter is slightly smaller than the diameter of the concave annular groove (39) of the limiting flange (24).

7. A molten salt storage tank system according to claim 1 that can save molten salt in the bottom dead zone, characterized in that: The vacuum main pipe (10) is equipped with a branch vent valve (9). When the molten salt storage tank (1) is nitrogen-sealed, the vent valve (9) is normally closed. When the molten salt storage tank (1) is not nitrogen-sealed, the vent valve (9) is normally open.

8. A molten salt storage tank system according to claim 1 that can save molten salt in the bottom dead zone, characterized in that: The balance pipe main pipe (11) is equipped with a balance pipe shut-off valve (12). When the molten salt storage tank (1) is filled with salt, the balance pipe shut-off valve (12) is opened. When the molten salt pump (5) pumps salt outward, the balance pipe shut-off valve (12) is closed.

9. A molten salt storage tank system according to claim 1 that can save molten salt in the bottom dead zone, characterized in that: A level gauge (6) is installed at the top of the molten salt suction pipe (4).

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