Filling system of fused salt phase change heat storage device

Abstract

The invention provides a molten salt phase change heat storage device filling system which comprises a molten salt tank, a molten salt supplementing device, a filling pipeline and a molten salt phase change heat storage device, and heating devices are arranged in the molten salt tank and the molten salt supplementing device. Automatic filling can be realized by using atmospheric pressure and gravitational potential energy of the fused salt phase change heat storage material on the premise of not using extra power. The problems that due to the fact that the melting point of the fused salt phase change heat storage material is relatively high, after a power source of a heating device is turned off, the fused salt phase change heat storage material of a fused salt pump at a filling valve can be rapidly solidified into a solid state, and filling cannot be safely, continuously and automatically conducted due to the fact that the fused salt phase change heat storage device is guided are solved.

Description

Technical Field

[0001] The invention relates to the field of molten salt phase change heat storage, and in particular to a filling system for a molten salt phase change heat storage device. Background Art

[0002] The phase change thermal storage device needs to be filled with phase change thermal storage materials inside, and the phase change of the phase change thermal storage material at the phase change temperature point is used to store thermal energy. At room temperature, the phase change thermal storage material is generally in a solid state. In order to be able to fill a specific mass of phase change thermal storage material in the phase change thermal storage device, the phase change thermal storage material generally needs to be heated and melted before being filled into the phase change thermal storage device. The general filling method is to lift the phase change thermal storage material heating device to a certain height, fill a certain amount of solid (generally powdered solid) phase change thermal storage material inside it, heat it to melt it into a liquid state, open the filling valve at the bottom of the phase change thermal storage material heating device, and use the gravity of the phase change thermal storage material itself to fill the liquid phase change thermal storage material into the phase change thermal storage device. Alternatively, use a pump to extract the melted phase change thermal storage material into the phase change thermal storage device.

[0003] The above filling method is generally suitable for low-temperature phase change thermal storage materials with low melting points. Low-temperature phase change thermal storage materials have low melting points. The phase change thermal storage materials remaining at the filling valve (generally made of metal) after filling can be melted by appropriately increasing the heating temperature and utilizing the thermal conductivity of the metal material. Therefore, the residual phase change thermal storage materials will not cause blockage of the filling valve.

[0004] However, molten salt phase change thermal storage materials are divided into one or more elements. Depending on the different proportions of their components, their melting points range from 150 to 300 ° C. When high-melting-point molten salt phase change thermal storage materials need to be filled, the method of appropriately raising the heating temperature and using the thermal conductivity of the metal material to melt the molten salt phase change thermal storage materials remaining at the filling valve is not applicable. This makes it impossible for the traditional filling system to open the filling valve normally before filling. When using a molten salt pump for filling, after the molten salt phase change thermal storage material cools down, the molten salt blocks the molten salt pump. The existing solution is to set a heating device at the filling valve or on the filling pipeline. Although it can solve the above problems, such a solution is inefficient and has great safety hazards. Because the melting point of the molten salt phase change thermal storage material is relatively high, after turning off the power of the heating device, the molten salt phase change thermal storage material at the filling valve and the molten salt pump will quickly solidify into a solid state, while the method of electric heating requires power off after the residual molten salt phase change thermal storage material melts before continuing to fill. Summary of the invention

[0005] In order to overcome the problems existing in the prior art, the present invention provides a molten salt phase change thermal storage device filling system which utilizes atmospheric pressure and the gravitational potential energy of the molten salt phase change thermal storage material itself to achieve automatic filling without the aid of additional power.

[0006] In order to achieve the above-mentioned purpose, the specific scheme of the filling system of the molten salt phase change thermal storage device of the present invention is as follows:

[0007] A molten salt phase-change heat storage device filling system comprises a molten salt tank, a molten salt replenishing device, a filling pipeline and the molten salt phase-change heat storage device, wherein a heating device is arranged in the molten salt tank and the molten salt replenishing device, the filling pipeline is sealed and fixedly connected with the molten salt tank and the molten salt replenishing device, the filling pipeline is made of metal, the molten salt replenishing device is arranged at the upper part of the filling pipeline, and a valve M2 is arranged on the filling pipeline connected to the lower part of the molten salt replenishing device, and liquid molten salt phase-change heat storage material is filled in the filling pipeline at the lower part of the molten salt replenishing device by controlling the opening and closing of the sealing valve M2, so as to increase the initial power for the filling of the molten salt phase-change heat storage device, and the molten salt phase-change heat storage device filling system utilizes atmospheric pressure and the gravitational potential energy of the liquid molten salt phase-change heat storage material in the molten salt tank and the molten salt replenishing device during the filling process to realize automatic filling.

[0008] Furthermore, the filling pipeline consists of three branches, namely, a first branch, a second branch and a third branch; wherein the first branch passes from the upper part of the molten salt tank into the lower part of the molten salt tank, and the horizontal height of the passing position is not lower than the liquid level after the molten salt phase change thermal storage material in the molten salt tank is melted into a liquid state; the second branch is sealed and fixedly connected to the bottom of the molten salt replenishment device through the valve M2; the third branch is used to connect the filling hole on the molten salt phase change thermal storage device; the setting height of the molten salt replenishment device is higher than the highest points of the first branch and the third branch.

[0009] Furthermore, a valve M1 is provided on the first branch, and a valve M3 is provided on the third branch. By adjusting the opening and closing states of the valves M1, M2, and M3 on the filling pipeline branch, the liquid level of the molten salt phase change thermal storage material in the filling pipeline can be adjusted.

[0010] Furthermore, the filling pipeline also has a fourth branch, and a valve M4 is provided on the fourth branch to connect with the third branch; the installation height of the molten salt replenishing device is higher than the highest point of the first branch and the third branch.

[0011] Furthermore, the first branch and the third branch are joined by a section of arc-shaped pipe, and the joining point of the three branches is located at a position where the vertical line of the arc vertices of the first branch and the third branch deviates toward the third branch; the height from the joining point of the three branches to the entrance level of the first branch first increases and then decreases; no valve is set on the first branch, and a valve M3 is set on the third branch.

[0012] Furthermore, the second branch is connected to the third branch in a straight line, and the first branch first extends downward at an acute angle with the third branch, and before entering the molten salt tank, the extension direction becomes vertically downward.

[0013] Furthermore, the third branch is provided with a diameter changer, and the diameter of the third branch is enlarged by the diameter changer.

[0014] Furthermore, the diameter change increases the diameter of the third branch to 1.25 times that of the first branch.

[0015] Furthermore, a certain slope is arranged at the bottom of the molten salt tank to ensure that after the molten salt phase change thermal storage material is heated and melted, during the filling process, the molten salt phase change thermal storage material in the molten salt tank can flow to the vicinity of the first branch entrance with the help of the slope of the bottom, and thus be completely discharged from the molten salt tank.

[0016] Furthermore, the molten salt is a monovalent or polyvalent molten salt with a melting point ranging from 150 to 300°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the composition structure of the molten salt phase change thermal storage device filling system according to the first embodiment of the present invention;

[0018] Figure 2 This is a schematic diagram of the composition structure of a filling pipeline of a filling system of a molten salt phase change thermal storage device according to the first embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of the composition structure of a filling pipeline of a filling system of a molten salt phase change thermal storage device according to the second embodiment of the present invention;

[0020] Figure 4 This is a schematic diagram of the composition structure of a filling pipeline of a filling system of a molten salt phase change thermal storage device according to the third embodiment of the present invention;

[0021] Figure 5 This is a schematic diagram of the composition structure of a filling pipeline of a filling system of a molten salt phase change thermal storage device according to a fourth embodiment of the present invention;

[0022] Figure 6 This is a schematic diagram of the composition structure of a filling pipeline of a filling system of a molten salt phase change thermal storage device according to Embodiment 5 of the present invention;

[0023] Figure 7 This is a schematic diagram of the composition structure of a filling pipeline of a filling system of a molten salt phase change thermal storage device according to Embodiment 6 of the present invention;

[0024] Among them: 100 is a molten salt tank, 200 is a molten salt replenishing device, 300 is a filling pipeline, 301 is a first branch, 302 is a second branch, 303 is a third branch, 304 is a fourth branch, M1 is a first branch valve, M2 is a second branch valve, M3 is a third branch valve, and M4 is a fourth branch valve. DETAILED DESCRIPTION

[0025] Figure 1FIG. 1 is a schematic diagram of the composition structure of the molten salt phase change thermal storage device filling system according to the first embodiment of the present invention. Figure 1 As shown, the molten salt phase change thermal storage device filling system mainly includes a molten salt tank 100, a molten salt replenishing device 200 and a filling pipeline 300. The molten salt tank 100 and the molten salt replenishing device 200 are used to contain molten salt phase change thermal storage materials of the same composition (ratio), and the molten salt phase change thermal storage materials are added through the top feeding port ( Figure 1 ) and is capable of heating the molten salt phase change thermal storage material ( Figure 1 The heating device is not shown in the figure), so that the molten salt phase change thermal storage material melts from a solid state to a liquid state. The filling pipeline 300 is made of stainless steel and has three branches, which are respectively used to connect the molten salt tank 100, the molten salt replenishing device 200 and the molten salt phase change thermal storage device 400, wherein the connection between the filling pipeline 300 and the molten salt tank 100 and the molten salt replenishing device 200 is a sealed fixed connection. The setting height of the molten salt replenishment device 200 is higher than the confluence point of the three branches of the filling pipeline 300 to ensure that there is a height difference between the liquid level of the molten salt phase change thermal storage material in the molten salt replenishment device 200 and the horizontal height of the confluence point of the three branches of the filling pipeline 300. Therefore, after the molten salt phase change thermal storage material in the molten salt tank 100 and the molten salt replenishment device 200 is heated and melted into a liquid state, when the molten salt phase change thermal storage device is filled, the liquid molten salt phase change thermal storage material in the molten salt replenishment device 200 flows into the corresponding branch of the filling pipeline 300, providing initial power for the startup of the filling system, thereby realizing unpowered automatic filling.

[0026] further, Figure 2 As shown, the filling pipeline 300 is composed of three branches, namely, a first branch 301, a second branch 302, and a third branch 303. The first branch 301 is passed from the upper part of the molten salt tank 100 to the lower part of the molten salt tank 100, and the horizontal height of the passing position is not lower than the liquid level of the molten salt phase change thermal storage material in the molten salt tank 100 after it melts into liquid; the second branch 302 is connected to the bottom of the molten salt replenishing device 200; and the third branch 303 is used to connect to the filling hole on the molten salt phase change thermal storage device 400.

[0027] In addition, in order to make the liquid level control of the molten salt phase change thermal storage material in the filling pipeline 300 simpler and more convenient, as Figure 2As shown, a valve M1 is provided on the first branch 301, a valve M2 is provided on the second branch 302, and a valve M3 is provided on the third branch 303. By adjusting the opening and closing states of the valves M1, M2, and M3 on the filling pipeline 300 branch, the liquid level height of the molten salt phase change thermal storage material in the filling pipeline 300 is adjusted, and the pressure state inside each branch in the filling pipeline 300 is adjusted, so that even if the initial power is not provided for the filling system, the filling system uses the internal pressure difference between the branches of the filling pipeline 300 to start the filling system; after the filling system is started, the height difference between the molten salt tank 100 and the molten salt phase change thermal storage device 400 causes the gravitational potential energy difference of the liquid molten salt phase change thermal storage material in the molten salt tank 100 and the molten salt phase change thermal storage device 400, so that the filling system can realize automatic filling without providing power for the filling system.

[0028] The working process of the above-mentioned molten salt phase change thermal storage device filling system is as follows: the valve M2 on the second branch 302 of the filling pipeline is closed, the valves M1 and M3 on the first branch 301 and the third branch 303 are opened, and the solid powder of the molten salt phase change thermal storage material with the same component (ratio) and specific is added to the molten salt tank 100 and the molten salt replenishing device 200 through the feeding port, and the heating devices in the molten salt tank 100 and the molten salt replenishing device 200 are turned on to melt the molten salt phase change thermal storage material into a liquid state. During the melting process, as the molten salt phase change thermal storage material melts, the liquid level of the molten salt phase change thermal storage material in the molten salt tank 100 and the molten salt replenishing device 200 will change. By continuing to add solid powder, the liquid level of the molten salt phase change thermal storage material is adjusted to meet the use requirements. Continue heating until the molten salt phase change thermal storage material in the molten salt tank 100 and the molten salt replenishing device 200 is completely melted into a liquid state.

[0029] After the molten salt phase-change thermal storage material in the molten salt tank 100 and the molten salt replenishment device 200 is completely melted into liquid, the valves M1 and M3 on the first branch 301 and the third branch 303 are closed to prepare for filling the molten salt phase-change thermal storage device. During filling, first slowly open the valve M2 to allow the molten salt phase-change thermal storage material in the molten salt replenishment device 200 to slowly flow into the filling pipeline 300. When the molten salt phase-change thermal storage material fills the first branch and the third branch between the confluence point of the three branches and the valve M1, close the valve M2. Then, simultaneously and quickly open the valves M1 and M3. Since there is a height difference between the horizontal height of the valve M1 and the liquid level of the molten salt phase change thermal storage material in the molten salt tank 100, there will be a residual air column between the valve M1 and the liquid level of the molten salt phase change thermal storage material; under the influence of gravity, after the valves M1 and M3 are opened at the same time, the molten salt phase change thermal storage materials in the first branch 301 and the third branch 303 will move downward respectively. Since the filling pipeline 300 is a sealed pipeline, the internal pressure of the residual air column will quickly become a negative pressure (lower than atmospheric pressure). Due to the effect of atmospheric pressure, the downward movement speed of the molten salt phase change thermal storage material in the first branch 301 gradually slows down until it stops. However, since the molten salt phase-change thermal storage material in the third branch 303 is still continuing to flow downward into the molten salt phase-change thermal storage device at this time, the pressure of the residual gas column will further decrease, and the difference between its internal pressure and the atmospheric pressure will further increase. Under the action of atmospheric pressure, the molten salt phase-change thermal storage material in the molten salt tank 100 is pressed into the first branch 301, and the speed of being pressed in gradually increases with the outflow of the molten salt phase-change thermal storage material in the third branch. When the molten salt phase-change thermal storage material rushes through the highest points in the first branch 301 and the third branch 303 due to the pressure difference and inertia, the residual gas column is discharged from the molten salt phase-change thermal storage material outflow port of the third branch 303 under the action of pressure difference and gravity, and the molten salt phase-change thermal storage material fills the first branch 301 and the third branch 303. Due to the gravitational potential energy difference caused by the height difference between the molten salt tank 100 and the molten salt replenishing device 200, the molten salt phase change thermal storage material in the molten salt tank 100 begins to automatically fill into the molten salt phase change thermal storage device 400 without additional power. After the molten salt phase change thermal storage device reaches the filling end, the valve M3 is closed.

[0030] During continuous filling, when a molten salt phase change thermal storage device reaches the filling end point and the filling is completed, the valve M3 is closed. Since the filling pipeline 300 is a sealed pipeline, when the valves M2 and M3 are closed, the molten salt phase change thermal storage material in the first branch 301 will not flow out due to the existence of atmospheric pressure. Then, after replacing another molten salt phase change thermal storage device that needs to be filled, the valve M3 is opened and the filling can continue.

[0031] In case of non-continuous filling or after the filling operation, in order to prevent the molten salt phase change thermal storage material remaining in the filling pipeline from condensing and blocking the filling system, the molten salt phase change thermal storage material in the filling system should be discharged. First, valves M1 and M2 are opened to discharge the residual molten salt phase change thermal storage material in the molten salt replenishing device 200, the second branch 302, and the first branch 301 into the molten salt tank 100; then, valve M3 is opened to discharge the residual molten salt phase change thermal storage material in the third branch 303, collect it, cool it, and then recycle it.

[0032] Figure 3 This is a schematic diagram of the structure of the second embodiment of the filling system of the molten salt phase change thermal storage device of the present invention. Figure 1 , Figure 2 Compared with the filling system of the molten salt phase change thermal storage device shown in the figure, the difference is that after the third branch 303 passes through the convergence point of the three branches, the diameter of the third branch 303 is enlarged by changing the diameter. As a preferred embodiment, the diameter of the third branch 303 becomes 1.25 times the diameter of the first branch 301. By setting a diameter change on the third branch 303 and changing the diameter of the third branch 303, during the startup of the filling system, the molten salt phase change thermal storage material in the third branch 303 moves downward due to gravity, driving the residual gas column in the filling pipeline 300 to move from the first branch 301 side to the third branch 303 side. During the movement, after encountering the diameter change, the gas pressure will decrease sharply, thereby creating a large negative pressure in the filling pipeline, which can increase the speed at which the molten salt phase change thermal storage material in the molten salt tank 100 is pressed into the first branch 301, and the liquid level of the molten salt phase change thermal storage material in the filling pipeline 300 passes the highest point quickly by inertia, ensuring the smooth progress of the filling process. The working process of the filling system of the molten salt phase change thermal storage device of this embodiment is the same as that of the first embodiment, and will not be repeated here.

[0033] Figure 4 This is a schematic diagram of the structure of the third embodiment of the filling system of the molten salt phase change thermal storage device of the present invention. Figure 1 , Figure 2Compared with the filling system of the molten salt phase change thermal storage device shown in the figure, the difference is that the top of the first branch 301 and the third branch 303 are connected to the second branch 302 at the convergence point through a section of arc-shaped pipeline; a certain slope is set at the bottom of the molten salt tank 100, and the entrance of the first branch 301 is located at the bottom of the slope of the molten salt tank 100. The top arc-shaped pipeline design is conducive to fully draining the residual molten salt phase change thermal storage material in the first branch and the third branch at the end of the filling operation, so as to prevent it from clogging the filling system after cooling and solidification. The bottom of the molten salt tank 100 is set with a certain slope to ensure that after the molten salt phase change thermal storage material is heated and melted, during the filling process, the molten salt phase change thermal storage material in the molten salt tank 100 can flow to the vicinity of the entrance of the first branch 301 with the help of the slope at the bottom, so as to be completely discharged from the molten salt tank 100. The working process of the molten salt phase change thermal storage device filling system of this embodiment is the same as that of the first embodiment, and will not be repeated here.

[0034] Figure 5 Schematic diagram of the structure of the fourth embodiment of the filling system of the molten salt phase change thermal storage device of the present invention. Figure 1 Compared with the filling system of the molten salt phase change thermal storage device shown in the figure, the difference is that the second branch 302 and the third branch 303 are connected in a straight line, the first branch 301 is first tilted downward and the angle between it and the third branch 303 is an acute angle, and then the extension direction is changed to vertically downward into the molten salt tank 100 (not shown in the figure). The second branch 302 and the third branch 303 connected in a straight line are conducive to preventing residual gas columns from being left in the third branch 303, so that the molten salt phase change thermal storage material can fully fill the third branch 303 before filling begins, providing sufficient initial power for the start of the filling system. The second branch 302 and the third branch 303 connected in a straight line, and the third branch 303 tilted downward are conducive to the filling system at the end of the filling operation, fully draining the residual molten salt phase change thermal storage material in the filling system, and preventing it from clogging the filling system after cooling and solidification. The working process of the molten salt phase change thermal storage device filling system of this embodiment is the same as that of the first embodiment, and will not be repeated here.

[0035] Figure 6 Schematic diagram of the structure of the fifth embodiment of the filling system of the molten salt phase change thermal storage device of the present invention. Figure 4 Compared with the filling system of the molten salt phase change thermal storage device shown in the figure, the difference is that the convergence point of the three branches of the filling pipeline 300 is located at the position where the vertical line of the arc vertices of the first branch 301 and the third branch 303 deviates to the third branch 303; the convergence point of the three branches to the entrance of the first branch 301 needs to be raised and then lowered. No valve is set on the first branch 301.

[0036] The working process of the above-mentioned molten salt phase change thermal storage device filling system is as follows: the valve M2 on the second branch 302 of the filling pipeline is closed, the valve M3 on the third branch 303 is opened, and the solid powder of the molten salt phase change thermal storage material with the same component (ratio) and specific is added to the molten salt tank 100 and the molten salt replenishing device 200 through the feeding port (not shown in the figure), and the heating device in the molten salt tank 100 and the molten salt replenishing device 200 is turned on to melt the molten salt phase change thermal storage material into a liquid state. During the melting process, as the molten salt phase change thermal storage material melts, the liquid level of the molten salt phase change thermal storage material in the molten salt tank 100 and the molten salt replenishing device 200 will change. By continuing to add solid powder, the liquid level of the molten salt phase change thermal storage material is adjusted to meet the use requirements. Continue heating until the molten salt phase change thermal storage material in the molten salt tank 100 and the molten salt replenishing device 200 is completely melted into a liquid state.

[0037] After the molten salt phase-change thermal storage material in the molten salt tank 100 and the molten salt replenishment device 200 is completely melted into liquid, the valve M3 on the third branch 303 is closed to prepare for filling the molten salt phase-change thermal storage device. During filling, first slowly open the valve M2 to allow the molten salt phase-change thermal storage material in the molten salt replenishment device 200 to slowly flow into the filling pipeline 300. When the molten salt phase-change thermal storage material fills the first branch and the third branch between the confluence point of the three branches and the valve M1, close the valve M2. Then, quickly open the valve M3.

[0038] Since there is a height difference between the highest point of the first branch 301 and the liquid level of the molten salt phase change thermal storage material in the molten salt tank 100, there will be a residual gas column between the highest point of the first branch 301 and the liquid level of the molten salt phase change thermal storage material; under the influence of gravity, after the valve M3 is opened, the molten salt phase change thermal storage materials in the first branch 301 and the third branch 303 will move downward respectively. Since the filling pipeline 300 is a sealed pipeline, the internal pressure of the residual gas column will quickly become a negative pressure (lower than atmospheric pressure). Due to the effect of atmospheric pressure, the downward movement speed of the molten salt phase change thermal storage material in the first branch 301 gradually slows down until it stops. However, since the molten salt phase-change thermal storage material in the third branch 303 is still continuing to flow downward into the molten salt phase-change thermal storage device at this time, the pressure of the residual gas column will further decrease, and the difference between its internal pressure and the atmospheric pressure will further increase. Under the action of atmospheric pressure, the molten salt phase-change thermal storage material in the molten salt tank 100 is pressed into the first branch 301, and the speed of being pressed in gradually increases with the outflow of the molten salt phase-change thermal storage material in the third branch. When the molten salt phase-change thermal storage material passes through the highest point of the first branch 301 due to the pressure difference and inertia, the residual gas column is discharged from the molten salt phase-change thermal storage material outflow port of the third branch 303 under the action of pressure difference and gravity, and the molten salt phase-change thermal storage material fills the first branch 301 and the third branch 303. Due to the gravitational potential energy difference caused by the height difference between the molten salt tank 100 and the molten salt replenishing device 200, the molten salt phase change thermal storage material in the molten salt tank 100 begins to automatically fill into the molten salt phase change thermal storage device 400 without additional power (not shown in the figure). After the molten salt phase change thermal storage device reaches the filling end, the valve M3 is closed.

[0039] During continuous filling, when a molten salt phase change thermal storage device reaches the filling end point and the filling is completed, the valve M3 is closed. Since the filling pipeline 300 is a sealed pipeline, when the valves M2 and M3 are closed, the molten salt phase change thermal storage material in the first branch 301 will not flow out due to the existence of atmospheric pressure. Then, after replacing another molten salt phase change thermal storage device that needs to be filled, the valve M3 is opened and the filling can continue.

[0040] In case of non-continuous filling or after the filling operation, in order to prevent the molten salt phase change thermal storage material remaining in the filling pipeline from condensing and blocking the filling system, the molten salt phase change thermal storage material in the filling system should be discharged. First, the valve M2 is opened to discharge the residual molten salt phase change thermal storage material in the molten salt replenishing device 200, the second branch 302, and the first branch 301 into the molten salt tank 100; then, the valve M3 is opened to discharge the residual molten salt phase change thermal storage material in the third branch 303, collect it, cool it, and then recycle it.

[0041] Figure 7 Schematic diagram of the structure of the sixth embodiment of the filling system of the molten salt phase change thermal storage device of the present invention. Figure 1 , Figure 2 Compared with the filling system of the molten salt phase change thermal storage device shown in the figure, the difference is that the filling pipeline 300 is above the first branch 301. A fourth branch 304 is arranged vertically upward; the outlet level of the fourth branch 304 is not lower than the height of the liquid level when the molten salt replenishing device 200 is in use; a valve M4 is arranged on the fourth branch 304 to exhaust the air in the filling pipeline 300 when the filling is started. As a preferred implementation of this embodiment, the position of the valve M4 is close to the confluence point of the fourth pipeline 304 and the first pipeline 301, so as to reduce the additional increase in the amount of air in the filling pipeline 300 due to the arrangement of the fourth branch 304 in the filling pipeline 300, thereby reducing the initial power of the filling system.

[0042] The working process of the molten salt phase change thermal storage device filling system is as follows: the valve M2 on the second branch 302 of the filling pipeline is closed, the valves M1, M3, and M4 on the first branch 301, the third branch 303, and the fourth branch 304 are opened, and the solid powder of the molten salt phase change thermal storage material with the same component (ratio) and specific is added to the molten salt tank 100 and the molten salt replenishing device 200 through the feeding port, and the heating devices in the molten salt tank 100 and the molten salt replenishing device 200 are turned on to melt the molten salt phase change thermal storage material into a liquid state. During the melting process, as the molten salt phase change thermal storage material melts, the liquid level of the molten salt phase change thermal storage material in the molten salt tank 100 and the molten salt replenishing device 200 will change. By continuing to add solid powder, the liquid level of the molten salt phase change thermal storage material is adjusted to meet the use requirements. Continue heating until the molten salt phase change thermal storage material in the molten salt tank 100 and the molten salt replenishing device 200 is completely melted into a liquid state.

[0043] After the molten salt phase-change thermal storage material in the molten salt tank 100 and the molten salt replenishment device 200 is completely melted into liquid, the valves M1 and M3 on the first branch 301 and the third branch 303 are closed to prepare for filling the molten salt phase-change thermal storage device. During filling, keep the valve M4 on the fourth branch 304 in an open state, first slowly open the valve M2, and allow the molten salt phase-change thermal storage material in the molten salt replenishment device 200 to slowly flow into the filling pipeline 300; the air in the filling pipeline 300 is discharged through the fourth branch 304. When the molten salt phase-change thermal storage material fills the first branch and the third branch between the confluence point of the first, second, and third branches and the valve M1, close the valves M2 and M4. Then, open the valves M1 and M3 simultaneously and quickly. Since there is a height difference between the horizontal height of the valve M1 and the liquid level of the molten salt phase change thermal storage material in the molten salt tank 100, there will be a residual air column between the valve M1 and the liquid level of the molten salt phase change thermal storage material; under the influence of gravity, after the valves M1 and M3 are opened at the same time, the molten salt phase change thermal storage materials in the first branch 301 and the third branch 303 will move downward respectively. Since the filling pipeline 300 is a sealed pipeline, the internal pressure of the residual air column will quickly become a negative pressure (lower than atmospheric pressure). Due to the effect of atmospheric pressure, the downward movement speed of the molten salt phase change thermal storage material in the first branch 301 gradually slows down until it stops. However, since the molten salt phase-change thermal storage material in the third branch 303 is still continuing to flow downward into the molten salt phase-change thermal storage device at this time, the pressure of the residual gas column will further decrease, and the difference between its internal pressure and the atmospheric pressure will further increase. Under the action of atmospheric pressure, the molten salt phase-change thermal storage material in the molten salt tank 100 is pressed into the first branch 301, and the speed of being pressed in gradually increases with the outflow of the molten salt phase-change thermal storage material in the third branch. When the molten salt phase-change thermal storage material rushes through the highest points in the first branch 301 and the third branch 303 due to the pressure difference and inertia, the residual gas column is discharged from the molten salt phase-change thermal storage material outflow port of the third branch 303 under the action of pressure difference and gravity, and the molten salt phase-change thermal storage material fills the first branch 301 and the third branch 303. Due to the gravitational potential energy difference caused by the height difference between the molten salt tank 100 and the molten salt replenishing device 200, the molten salt phase change thermal storage material in the molten salt tank 100 begins to automatically fill into the molten salt phase change thermal storage device 400 without additional power (not shown in the figure). After the molten salt phase change thermal storage device reaches the filling end, the valve M3 is closed.

[0044] During continuous filling, when a molten salt phase change thermal storage device reaches the filling end point and the filling is completed, the valve M3 is closed. Since the filling pipeline 300 is a sealed pipeline, when the valves M2, M3, and M4 are closed, the molten salt phase change thermal storage material in the first branch 301 will not flow out due to the existence of atmospheric pressure. Then, after replacing another molten salt phase change thermal storage device that needs to be filled, the valve M3 is opened and the filling can continue.

[0045] In case of non-continuous filling or after the filling operation, the molten salt phase change thermal storage material in the filling system should be discharged to prevent the molten salt phase change thermal storage material remaining in the filling pipeline from condensing and blocking the filling system. First, valves M1 and M2 are opened to discharge the residual molten salt phase change thermal storage material in the molten salt replenishing device 200, the second branch 302, and the first branch 301 into the molten salt tank 100; then, valves M3 and M4 are opened to discharge the residual molten salt phase change thermal storage material in the third branch 303 and the fourth branch 304, and the molten salt phase change thermal storage material is collected, cooled, and then recycled.

[0046] The molten salt phase change heat storage device filling system of the present invention, after raising the horizontal height of the molten salt tank, utilizes the gravitational potential energy difference caused by the horizontal height difference between the molten salt tank and the molten salt phase change heat storage device to realize the "unpowered" filling of the molten salt phase change heat storage device. During the filling process of the filling system, the filling pipeline made of stainless steel will maintain a certain high temperature due to the conduction of heat, so that the molten salt phase change heat storage material inside the filling pipeline can always remain in a liquid state. After the filling is completed, the residual molten salt phase change heat storage material in the filling system is promptly emptied, which solves the problem in the traditional filling method that the valve at the bottom of the molten salt tank cannot be heated, causing the residual molten salt at the bottom to solidify and block the valve, so that the subsequent filling cannot be carried out smoothly.

[0047] In the molten salt phase-change thermal storage device of the present invention, during the filling process of the filling system, the stainless steel filling pipeline will maintain a certain high temperature due to heat conduction, and the internal molten salt phase-change thermal storage material will not solidify, so it will not cause blockage of the pipeline components. After the filling is completed, the molten salt phase-change thermal storage material in the pipeline can be fully emptied, and there will be no residual molten salt phase-change thermal storage material causing blockage of the filling pipeline.

[0048] It is understood that the present invention is described by some embodiments, and those skilled in the art know that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application belong to the scope protected by the present invention.

Claims

1. A filling system for a molten salt phase change heat storage device, comprising a molten salt tank, a molten salt replenishing device, a filling pipeline and a molten salt phase change heat storage device, wherein a heating device is provided in the molten salt tank and the molten salt replenishing device, the filling pipeline is sealed and fixedly connected with the molten salt tank and the molten salt replenishing device, and the filling pipeline is made of metal, characterized in that: The molten salt replenishing device is arranged at the upper part of the filling pipeline, and a valve M2 is arranged on the filling pipeline connected to the lower part of the molten salt replenishing device. The liquid molten salt phase change thermal storage material is filled in the filling pipeline at the lower part of the molten salt replenishing device by controlling the opening and closing of the sealing valve M2, so as to increase the initial power for the filling of the molten salt phase change thermal storage device. During the filling process of the molten salt phase change thermal storage device filling system, the atmospheric pressure and the gravitational potential energy of the liquid molten salt phase change thermal storage material in the molten salt tank and the molten salt replenishing device are utilized to realize automatic filling.

2. The molten salt phase change thermal storage device filling system according to claim 1, characterized in that: The filling pipeline consists of three branches, namely, a first branch, a second branch and a third branch; wherein the first branch passes from the upper part of the molten salt tank into the lower part of the molten salt tank, and the horizontal height of the passing position is not lower than the liquid level after the molten salt phase change thermal storage material in the molten salt tank is melted into liquid; the second branch is sealed and fixedly connected to the bottom of the molten salt replenishment device through the valve M2; the third branch is used to connect the filling hole on the molten salt phase change thermal storage device; the setting height of the molten salt replenishment device is higher than the highest point of the first branch and the third branch.

3. The molten salt phase change thermal storage device filling system according to claim 2, characterized in that: A valve M1 is provided on the first branch, and a valve M3 is provided on the third branch. By adjusting the opening and closing states of the valves M1, M2, and M3 on the filling pipeline branch, the liquid level of the molten salt phase change thermal storage material in the filling pipeline can be adjusted.

4. The molten salt phase change thermal storage device filling system according to claim 2 or 3, characterized in that: The filling pipeline also has a fourth branch, and a valve M4 is arranged on the fourth branch to connect with the third branch; the installation height of the molten salt replenishing device is higher than the highest point of the first branch and the third branch.

5. The molten salt phase change thermal storage device filling system according to any one of claims 2 to 4, characterized in that: The first branch and the third branch are joined by a section of arc-shaped pipe, and the joining point of the three branches is located at a position where the vertical line of the arc vertices of the first branch and the third branch deviates toward the third branch; the height from the joining point of the three branches to the entrance level of the first branch first rises and then falls; no valve is set on the first branch, and a valve M3 is set on the third branch.

6. The molten salt phase change thermal storage device filling system according to claim 5, characterized in that: The second branch is connected to the third branch in a straight line, and the first branch first extends downward at an acute angle with the third branch, and before entering the molten salt tank, the extension direction becomes vertically downward.

7. The molten salt phase change thermal storage device filling system according to claim 6, characterized in that: The third branch is provided with a diameter changer, and the diameter of the third branch is enlarged by the diameter changer.

8. The molten salt phase change thermal storage device filling system according to claim 7, characterized in that: The diameter change increases the diameter of the third branch to 1.25 times that of the first branch.

9. The molten salt phase change thermal storage device filling system according to any one of claims 1 to 8, characterized in that: The bottom of the molten salt tank is provided with a certain slope to ensure that after the molten salt phase change thermal storage material is heated and melted, during the filling process, the molten salt phase change thermal storage material in the molten salt tank can flow to the vicinity of the first branch entrance with the help of the slope of the bottom, and thus be completely discharged from the molten salt tank.

10. The molten salt phase change thermal storage device filling system according to claim 9, characterized in that: The molten salt is a monovalent or polyvalent molten salt with a melting point ranging from 150 to 300°C.

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