Salt dissolving device and application method thereof
By using ultrasonic waves and heating parts to treat single salts in the salt-decompression device, the problem of difficulty in removing moisture in the single salt is solved, the salt-decompression rate is improved and the energy consumption is reduced, and the efficiency and quality of the salt-decompression process is ensured.
Patent Information
- Application Number
- CN202510466822.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-15
- Publication Date
- 2025-07-11
AI Technical Summary
In the prior art, it is difficult to effectively remove the moisture in the single salt during the salt removal process, resulting in high energy consumption, slow salt removal rate and increased corrosion of molten salt on metal materials.
The salt-removing device, including a first treatment unit and a second treatment unit, uses ultrasonic waves and heating parts to process the single salt, remove moisture through ultrasonic strengthening and heat transfer strengthening, and then mix the moisture-removing single salt with other monosals and heat-melting to increase the salt-removing rate and reduce energy consumption.
Effectively increase the salt rate, reduce energy consumption during the salt purification process, and reduce the ion content of molten salt impurities to ensure the quality of salt purification.
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Figure CN120285877A_ABST
Abstract
Description
Technical Field
[0001] Embodiments of the present disclosure belong to the technical field of molten salt thermal energy storage, and particularly relate to a salt melting device and an application method thereof. Background Art
[0002] At present, renewable energy sources such as wind energy and solar energy in China have been developing rapidly year by year. Coupled with the increasing annual electricity consumption of the whole society, the peak-valley difference of power grid electricity consumption is increasing day by day, and the power grid's demand for low-cost and long-life energy storage technologies is getting stronger and stronger. Molten salt energy storage technology can convert electrical energy into thermal energy for storage, with the advantages of low average cost, long service life, and clean and pollution-free, and is one of the main energy storage means for coping with the development of new energy in the future.
[0003] Molten salt is an excellent medium- and high-temperature heat storage medium with low vapor pressure, good fluidity, and high heat storage temperature. The type of molten salt with the largest engineering application scale at present is solar salt (40% potassium nitrate + 60% sodium nitrate), which is mainly used in solar thermal power plants. The biggest advantage of solar salt is good thermal stability, low corrosion, and very low water content in single salts. The disadvantage is that the freezing point is too high, about 220°C, which is not suitable for the molten salt thermal energy storage system on the coal-fired power generation unit side. The melting point of ternary molten salt (53% potassium nitrate + 7% sodium nitrate + 40% sodium nitrite) is about 142°C, and some low-melting salts containing calcium nitrate (the industrial product is calcium nitrate tetrahydrate) are more suitable for the molten salt thermal energy storage transformation of coal-fired power generation units. However, one of the problems they face is how to quickly and low-energy remove the water in single salts. In related technologies, it is difficult to remove the water in single salts during the actual salt melting process. For example, the crystal water in calcium nitrate. During the heating and water removal process, a large amount of heat is transferred to the ambient air, resulting in high energy consumption and slow salt melting rate; the water content in liquid molten salt is relatively high, and the corrosion of molten salt to metal materials increases. Summary of the Invention
[0004] Embodiments of the present disclosure aim to at least solve one of the technical problems existing in the prior art, and provide a salt melting device and an application method thereof.
[0005] On the one hand, embodiments of the present disclosure provide a salt melting device, and the salt melting device includes a first processing unit and a second processing unit;
[0006] The first processing unit includes a first box body with a first feed port opened on the top wall and used for receiving at least one first single salt, a ventilation member penetrating through the top wall of the first box body and used for extracting ambient air from the feed port and discharging it, a first heating member penetrating through the top wall of the first box body and used for heating the first single salt, and an ultrasonic member arranged in the first box body and used for emitting ultrasonic waves to the first single salt;
[0007] The second processing unit includes a second box body with a second feed port opened on the top wall and used for receiving at least one second single salt, and a second heating member penetrating through the top wall of the second box body and used for heating the single salt therein; wherein,
[0008] The bottom wall of the first box body is higher than the bottom wall of the second box body in the horizontal direction. The bottom wall of the first box body is communicated with the second box body through a first pipeline in series with a first salt drainage valve. The side wall of the first box body is communicated with the second box body through a second pipeline in series with a cut-off valve. The second pipeline is higher than the first pipeline in the horizontal direction.
[0009] Optionally, the salt melting device further includes a salt supply pipeline in series with a salt supply valve, a reflux pipeline in series with a reflux valve, and a molten salt pump;
[0010] The first end of the molten salt pump is located in the second box body, and its second end is respectively connected to the first ends of the salt supply pipeline and the reflux pipeline; the second end of the salt supply pipeline is communicated with a salt storage tank, and the second end of the reflux pipeline is communicated with the first box body.
[0011] Optionally, the first processing unit further includes a first spray head, the second processing unit further includes a second spray head and a third pipeline in series with a second salt drainage valve;
[0012] The first spray head is located in the first box body and is communicated with the second end of the reflux pipeline. The second spray head is located in the second box body and is connected to the second pipeline.
[0013] Optionally, both the ultrasonic member and the first spray head are arranged on the side wall of the first box body, and the first spray head is located between the ultrasonic member and the first feed port;
[0014] The second spray head is arranged on the side wall of the second box body, and the second spray head is located between the first pipeline and the second feed port.
[0015] Optionally, the first heating member is located between the first feed port and the air guiding member, and the second heating member is located between the second feed port and the molten salt pump.
[0016] Optionally, the water content of the first single salt is higher than that of the second single salt.
[0017] Optionally, both the first box body and the second box body are metal box bodies, the air guiding member is an air guide device, and the ultrasonic member is an ultrasonic emitter.
[0018] Optionally, both the first heating member and the second heating member include a plurality of resistance heating tubes;
[0019] A plurality of the resistance heating tubes are vertically and spacedly inserted into corresponding boxes, and the resistance heating tube includes a resistance wire and an insulating and heat-conducting layer covering the resistance wire.
[0020] Optionally, a spiral or fin-shaped fin structure for increasing the heat exchange area is further arranged on the outer surface of the part of the resistance heating tube located in the corresponding box.
[0021] On the other hand, an embodiment of the present disclosure provides an application method of a salt melting device, adopting the salt melting device described above, and the application method includes:
[0022] Startup stage: Add the first single salt into the first box through the first feed port, start the first heating element, the air guiding element and the ultrasonic element until the liquid level height in the first box corresponds to the height of the second pipeline; count the corresponding first total mass of the first single salt input in the startup stage;
[0023] Continuous feeding stage: Continuously add the first single salt into the first box through the first feed port until the liquid level height in the first box reaches a preset value; count the corresponding second total mass of the first single salt input in the continuous feeding stage;
[0024] Melting stage: Calculate the second single salt to be input according to the second total mass and the mixing molten salt formula ratio, and add the corresponding second single salt into the second box from the second feed port according to the calculation result; start the second heating element and the isolation valve, and make the liquid salt in the first box flow into the second box by gravity until the liquid level height in the first box is lower than the second pipeline and all the mixed salt in the second box is melted into a liquid state.
[0025] For a salt melting device and its application method according to an embodiment of the present disclosure, first remove the moisture in the first single salt with a higher water content through ultrasonic strengthening and heat transfer strengthening, and then mix and heat-melt the first single salt after removing the moisture with the second single salt, which can effectively improve the salt melting rate, reduce the energy consumption in the salt melting process, reduce the content of impurity ions in the molten salt, and ensure the salt melting quality. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 It is a schematic structural diagram of a salt melting device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0027] To enable those skilled in the art to better understand the technical solutions of the present disclosure, the present disclosure will be further described in detail below with reference to the drawings and specific embodiments.
[0028] As Figure 1As shown, a salt dissolving device 100, the salt dissolving device 110 includes a first processing unit 110 and a second processing unit 120. The first processing unit 110 includes a first box body 112 with a first feed port 111 opened on the top wall and used for receiving at least one first single salt, a ventilation member 113 penetrating through the top wall of the first box body 112 and used for extracting ambient air from the feed port 111 and discharging it, a first heating member 114 penetrating through the top wall of the first box body 112 and used for heating the first single salt, and an ultrasonic member 115 disposed in the first box body 112 and used for emitting ultrasonic waves to the first single salt.
[0029] The second processing unit 120 includes a second box body 122 with a second feed port 121 opened on the top wall and used for receiving at least one second single salt, and a second heating member 123 penetrating through the top wall of the second box body 122 and used for heating the single salt therein. The bottom wall of the first box body 112 is higher than the bottom wall of the second box body 122 in the horizontal direction. The bottom wall of the first box body 112 is communicated with the second box body 122 through a first pipeline 131 with a first salt discharging valve 130 connected in series. The side wall of the first box body 112 is communicated with the second box body 122 through a second pipeline 141 with a cut-off valve 140 connected in series. The second pipeline 141 is higher than the first pipeline 131 in the horizontal direction.
[0030] Specifically, as Figure 1 shown, the first processing unit 110 constitutes a first salt dissolving area, and the second processing unit 120 constitutes a second salt dissolving area. The middle part of the first box body 112 is communicated with the upper part of the second box body 122 through a second pipeline 141 with a cut-off valve 140 connected in series. The bottom of the first box body 112 is communicated with the lower part of the second box body 122 through a first pipeline 131 with a first salt discharging valve 130 connected in series. The first box body 112 is higher than the second box body 122.
[0031] Furthermore, the salt dissolving device 100 further includes a salt supply pipeline 151 with a salt supply valve 150 connected in series, a return pipeline 161 with a return valve 160 connected in series, and a molten salt pump 200. The first end of the molten salt pump 200 is located in the second box body 122, and its second end is respectively connected to the first ends of the salt supply pipeline 151 and the return pipeline 161. The second end of the salt supply pipeline 151 is communicated with a salt storage tank, and the second end of the return pipeline 161 is communicated with the first box body 112.
[0032] The first processing unit 110 further includes a first spray head 116. The second processing unit 120 further includes a second spray head 124 and a third pipeline 127 with a second salt discharging valve 126 connected in series. The first spray head 116 is located in the first box body 112 and is communicated with the second end of the return pipeline 161. The second spray head 124 is located in the second box body 122 and is connected to the second pipeline 141.
[0033] Both the ultrasonic component 115 and the first spray head 116 are arranged on the side wall of the first box body 112, and the first spray head 116 is located between the ultrasonic component 115 and the first feed inlet 111. The second spray head 124 is arranged on the side wall of the second box body 122, and the second spray head 124 is located between the first pipeline 131 and the second feed inlet 121. The first heating component 114 is located between the first feed inlet 111 and the air guiding component 113, and the second heating component 123 is located between the second feed inlet 121 and the molten salt pump 200.
[0034] Specifically, as Figure 1 shown, in the first salt melting area, a first feed inlet 111, a first heating component 114 and an air guiding component 113 are arranged at the top of the first box body 112. The first feed inlet 111 and the air guiding component 113 are respectively arranged on both sides of the first heating component 114. The ultrasonic component 115 is installed at the lower part of the first box body 112, and the first spray head 116 is installed between the ultrasonic component 115 and the first feed inlet 111.
[0035] In the second salt melting area, a second feed inlet 121, a second heating component 123 and a molten salt pump 200 are arranged at the top of the second box body 122. The second feed inlet 121 and the molten salt pump 200 are respectively installed on both sides of the second heating component 123. The second spray head 124 is installed between the first pipeline 131 and the second feed inlet 121, and the second spray head 124 is connected to the second pipeline 141. The outlet of the molten salt pump 200 is divided into two paths, one path is connected to the first spray head 116 through a reflux valve 160, and the other path is connected to the salt storage tank through a salt supply valve 150.
[0036] The air guiding component 113 sucks the ambient air from the first feed inlet 111 and then sends it out, so as to timely take away the water vapor precipitated from the first single salt, reduce the partial pressure of water in the ambient air in contact with it, and accelerate the water removal rate. The ultrasonic component 115 generates cavities and vibrations in the liquid salt by emitting high-frequency sound waves, thereby promoting the vaporization of water molecules and reducing the heat consumption in the water removal process.
[0037] The isolation valve 140 is used to control the amount of liquid salt flowing into the second box body 122, realize salt melting zoning and control the single salt ratio in the mixed molten salt to meet the standard ratio. The isolation valve 140 can also wash the second single salt fed by conveying liquid salt below the second feed inlet 121, and accelerate the flow of the second single salt towards the second heating component 123. The reflux valve 160 sends a small amount of liquid mixed salt to the lower part of the first feed inlet 111 through the molten salt pump 200, washes the first single salt fed, and accelerates the flow of the first single salt towards the first heating component 114, improving the heat transfer rate. It should be noted that both the first single salt and the second single salt are solid salts, and the water content of the first single salt is higher than that of the second single salt.
[0038] The isolation valve 140, the first desalting valve 130 are connected to the front and rear pipelines by flanges, which is convenient for installation and disassembly. The first box body 112 and the second box body 122 can also be disassembled and transported independently, improving the flexible operation ability of the salt melting device 110.
[0039] Exemplarily, the first box body 112 and the second box body 122 are both metal box bodies, the air guiding member 113 is an air guide device, and the ultrasonic member 115 is an ultrasonic transmitter.
[0040] Both the first heating member 114 and the second heating member 123 include a plurality of resistance heating tubes 300. The plurality of resistance heating tubes 300 are vertically and spacedly inserted into the corresponding box bodies (112, 122), and the resistance heating tubes 300 are in direct contact with the molten salt. The resistance heating tube 300 includes a resistance wire and an insulating and heat-conducting layer covering the resistance wire.
[0041] The outer surface of the part of the resistance heating tube 300 located in the corresponding box body (112, 122) is also provided with a spiral or sheet-shaped fin structure for increasing the heat exchange area. It is used to increase the contact area between water molecules and the solid heat source, increase the nucleation position, and accelerate the vaporization and precipitation rate.
[0042] As a specific exemplary illustration, as Figure 1 shown, the specific working mode of the salt melting device 100 is as follows:
[0043] Startup stage: The first single salt with a relatively high water content is put into the first box body 112 from the first feed port 111, which may include one or more water-containing single salts. The first heating member 114 converts electrical energy into heat energy to heat the first single salt, and the first single salt changes from a solid state to a liquid state. The air guiding member 113 sucks ambient air into the first box body 112 continuously and then discharges high-humidity air. The ultrasonic member 115 emits ultrasonic waves with a fixed frequency to increase the rate of water molecule precipitation. When the liquid level reaches the installation height of the isolation valve 140 or the second pipeline 141, that is, when the liquid level reaches the required liquid level difference, the total mass of the solid salt of the first single salt input for the first time is counted.
[0044] Continuous feeding stage: The first single salt with a relatively high water content is continuously put into the first box body 112 from the first feed port 111. After water removal, when the liquid level reaches the preset value, the total mass of the solid salt of the second single salt input for the second time is counted.
[0045] Melting stage: Calculate the total mass of other component salts (including one or more water-containing single salts, and the water-containing single salt is the second single salt) according to the total mass of the second single salt solid salt input in the continuous feeding stage and the mixing molten salt formula ratio. Input the corresponding quantity of other component solid salts into the second box body 122 from the second feed port 121 according to the calculation result. Turn on the second heating element 123 to convert electrical energy into heat energy to heat the solid salt (the second single salt). At the same time, turn on the isolation valve 140, and the molten salt in the first box body 112 flows into the second box body 122 through the second nozzle 124 by gravity until the liquid level height in the first box body 112 is lower than the isolation valve 140 or the second pipeline 141. During this process, the molten salt in the first box body 112 flushes the solid salt in the second box body 122, which can also improve the heat transfer rate. When all the mixed molten salt in the second box body 122 is melted and the temperature exceeds the melting point temperature by more than 20 °C, the molten salt pump 200 can be started to send the molten salt to the salt storage tank for storage, and the molten salt pump 200 is stopped when the liquid level reaches the lowest level.
[0046] Repeat the continuous feeding stage and the melting stage, continuously melt and mix the solid salts (the first single salt and the second single salt) in different zones and send them to the salt storage tank for storage. When too much of the first single salt is fed into the first box body 112 in a short time, the molten salt pump 200 and the reflux valve 160 can be turned on, and a small amount of liquid mixed salt is sent to the lower part of the first feed port 111 through the reflux valve 160 and the first nozzle 116 to flush the fed first single salt, accelerating the flow of the first single salt towards the first heating element 114 and enhancing the heat transfer rate.
[0047] When the salt melting device 100 is out of service, open the first salt drainage valve 130 to drain all the molten salt in the first box body 112 to the second box body 122 by gravity. Turn on the molten salt pump 200 and the salt supply valve 150 to transport the mixed salt to the salt storage tank, and the remaining mixed salt at the bottom of the second box body 122 is discharged and recycled through the second salt drainage valve 126 and the third pipeline 127.
[0048] The salt melting device of the embodiment of the present disclosure first melts the single salt with a higher water content in a separate zone, removes the water therein by ultrasonic strengthening and heat transfer strengthening methods, and then mixes and heats the water-removed single salt with other component salts to effectively improve the salt melting rate, reduce the energy consumption during the salt melting process, reduce the content of impurity ions in the molten salt, and ensure the salt melting quality.
[0049] On the other hand, the embodiment of the present disclosure provides an application method of a salt melting device, which uses the salt melting device described above. The specific structure of the salt melting device can refer to the relevant descriptions above and will not be elaborated here. The application method includes:
[0050] Startup stage: Add the first single salt into the first box through the first feed port, and start the first heating element, air guiding element and ultrasonic element until the liquid level height in the first box corresponds to the height of the second pipeline. Statistically record the corresponding first total mass of the first single salt input during the startup stage.
[0051] Continuous feeding stage: Continuously add the first single salt into the first box through the first feed port until the liquid level height in the first box reaches the preset value. Statistically record the corresponding second total mass of the first single salt input during the continuous feeding stage.
[0052] Melting stage: Calculate the second single salt to be input according to the second total mass and the mixing molten salt formula ratio, and add the corresponding second single salt into the second box from the second feed port according to the calculation result. Start the second heating element and the isolation valve, and let the liquid salt in the first box flow into the second box by gravity until the liquid level height in the first box is lower than the second pipeline and all the mixed salt in the second box is melted into liquid.
[0053] Specifically, with reference to Figure 1 When applying the salt melting device 100, it is as follows:
[0054] Startup stage: Put the first single salt with a relatively high water content into the first box 112 from the first feed port 111, which can include one or more water-containing single salts. The first heating element 114 converts electrical energy into heat energy to heat the first single salt, and the first single salt changes from solid state to liquid state. The air guiding element 113 sucks in ambient air and continuously enters the first box 112, and then discharges high-humidity air. The ultrasonic element 115 emits ultrasonic waves with a fixed frequency to increase the rate of water molecule precipitation. When the liquid level height reaches the installation height of the isolation valve 140 or the second pipeline 141, that is, the liquid level height meets the liquid level difference requirement, statistically record the total mass of the first single salt solid salt input for the first time.
[0055] Continuous feeding stage: Continuously put the first single salt with a relatively high water content into the first box 112 from the first feed port 111. After water removal, when the liquid level reaches the preset value, statistically record the total mass of the second single salt solid salt input for the second time.
[0056] Melting stage: Calculate the total mass of other component salts (including one or more water-containing single salts, and the water-containing single salt is the second single salt) according to the total mass of the second single salt solid salt input in the continuous feeding stage and the mixing molten salt formula ratio. Input the corresponding quantity of other component solid salts into the second box body 122 from the second feed port 121 according to the calculation result. Turn on the second heating element 123 to convert electrical energy into heat energy to heat the solid salt (the second single salt). At the same time, turn on the partition valve 140, and the molten salt in the first box body 112 flows into the second box body 122 through the second spray head 124 by gravity until the liquid level height in the first box body 112 is lower than the partition valve 140 or the second pipeline 141. During this process, the molten salt in the first box body 112 flushes the solid salt in the second box body 122, which can also improve the heat transfer rate. When all the molten salt in the second box body 122 is melted and the temperature exceeds the melting point temperature by more than 20 °C, the molten salt pump 200 can be started to send the molten salt to the salt storage tank for storage, and the molten salt pump 200 is stopped when the liquid level reaches the lowest level.
[0057] Repeat the continuous feeding stage and the melting stage, continuously melt and mix the solid salts (the first single salt and the second single salt) in different zones and send them to the salt storage tank for storage. When too much of the first single salt is fed into the first box body 112 in a short time, the molten salt pump 200 and the reflux valve 160 can be turned on, and a small amount of the liquid mixed salt is sent to the lower part of the first feed port 111 through the reflux valve 160 and the first spray head 116 to flush the fed first single salt, accelerating the flow of the first single salt towards the first heating element 114 and enhancing the heat transfer rate.
[0058] When the salt melting device 100 is shut down, open the first salt drainage valve 130 to drain all the molten salt in the first box body 112 to the second box body 122 by gravity. Turn on the molten salt pump 200 and the salt supply valve 150 to transport the mixed salt to the salt storage tank, and the remaining mixed salt at the bottom of the second box body 122 is discharged and recycled through the second salt drainage valve 126 and the third pipeline 127.
[0059] It can be understood that the above embodiments are merely exemplary embodiments adopted to illustrate the principle of the present disclosure. However, the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present disclosure, and these modifications and improvements are also regarded as the protection scope of the present disclosure.
Claims
1. A salt dissolving device, characterized in that, The salt melting device includes a first processing unit and a second processing unit; The first processing unit includes a first box body with a first feed inlet opened on the top wall and used for receiving at least one first single salt, a ventilation member penetrating through the top wall of the first box body and used for extracting ambient air from the feed inlet and discharging it, a first heating member penetrating through the top wall of the first box body and used for heating the first single salt, and an ultrasonic member arranged in the first box body and used for emitting ultrasonic waves to the first single salt; The second processing unit includes a second box body with a second feed inlet opened on the top wall and used for receiving at least one second single salt, and a second heating member penetrating through the top wall of the second box body and used for heating the single salt therein; wherein, The bottom wall of the first box body is higher than the bottom wall of the second box body in the horizontal direction. The bottom wall of the first box body is communicated with the second box body through a first pipeline with a first salt discharging valve connected in series. The side wall of the first box body is communicated with the second box body through a second pipeline with a cut-off valve connected in series. The second pipeline is higher than the first pipeline in the horizontal direction.
2. The salt dissolving device according to claim 1, wherein, The salt melting device further includes a salt supply pipeline with a salt supply valve connected in series, a reflux pipeline with a reflux valve connected in series, and a molten salt pump; The first end of the molten salt pump is located in the second box body, and its second end is respectively connected to the first ends of the salt supply pipeline and the reflux pipeline; the second end of the salt supply pipeline is communicated with a salt storage tank, and the second end of the reflux pipeline is communicated with the first box body.
3. The salt dissolving device according to claim 2, wherein The first processing unit further includes a first spray head, the second processing unit further includes a second spray head and a third pipeline with a second salt discharging valve connected in series; The first spray head is located in the first box body and is communicated with the second end of the reflux pipeline, and the second spray head is located in the second box body and is connected to the second pipeline.
4. The salt dissolving device according to claim 3, characterized in that, The ultrasonic member and the first spray head are both arranged on the side wall of the first box body, and the first spray head is located between the ultrasonic member and the first feed inlet; The second spray head is arranged on the side wall of the second box body, and the second spray head is located between the first pipeline and the second feed inlet.
5. The salt dissolving device according to claim 4, wherein The first heating member is located between the first feed inlet and the ventilation member, and the second heating member is located between the second feed inlet and the molten salt pump.
6. The salt dissolving device according to any one of claims 1 to 5, characterized in that The water content of the first single salt is higher than that of the second single salt.
7. The salt dissolving device according to any one of claims 1 to 5, characterized in that, Both the first box body and the second box body are metal box bodies, the ventilation member is a ventilation device, and the ultrasonic member is an ultrasonic wave emitter.
8. The salt dissolving device according to any one of claims 1 to 5, characterized in that Both the first heating member and the second heating member include a plurality of resistance heating tubes; The plurality of resistance heating tubes are vertically and spacedly inserted into the corresponding box body. The resistance heating tube includes a resistance wire and an insulating heat-conducting layer covering the resistance wire.
9. The salt dissolving device according to claim 8, wherein, A spiral or sheet-shaped fin structure for increasing the heat exchange area is further arranged on the outer surface of the part of the resistance heating tube located in the corresponding box body.
10. A method for applying a salt dissolving device, characterized in that, Using the salt melting device according to any one of claims 1 to 9, the application method includes: Startup stage: Add the first single salt into the first box body through the first feed inlet, start the first heating member, the ventilation member and the ultrasonic member until the liquid level height in the first box body corresponds to the height of the second pipeline; count the corresponding first total mass of the first single salt input in the startup stage; Continuous feeding stage: Continuously add the first single salt into the first box through the first feed port until the liquid level height in the first box reaches the preset value; count the corresponding second total mass of the first single salt input during the continuous feeding stage. Melting stage: Calculate the second single salt to be input according to the second total mass and the mixing molten salt formula ratio, and add the corresponding second single salt into the second box from the second feed port according to the calculation result; start the second heating element and the isolation valve, and make the liquid salt in the first box flow into the second box by gravity until the liquid level height in the first box is lower than the second pipeline and all the mixed salt in the second box is melted into liquid.