A molten salt heat storage device with purging function and a purging method

Abstract

The application relates to the technical field of fused salt energy storage, in particular to a fused salt heat storage device with a purging function and a purging method. The device comprises a heat storage tank, a corrugated plate is arranged in the heat storage tank, the corrugated plate and a bottom area of the heat storage tank form a purging area, the corrugated plate and an upper area of the heat storage tank form a main heat storage area; an arc-shaped part forms a mixed flow area on the side of the purging area; through holes are arranged on the corrugated plate; a flow channel is arranged in the heat storage tank; the device further comprises a bypass pipe, a bypass pump, a heater, an air compressor and a controller; one end of the bypass pipe is communicated with the main heat storage area, and the bypass pump is arranged on the bypass pipe; the heater and the air compressor are both communicated with the flow channel, a first switch valve is arranged on the communication path of the heater and the flow channel, and a second switch valve is arranged on the communication path of the air compressor and the flow channel. In view of the poor treatment effect of solid precipitation and crystallization precipitation in the fused salt storage tank in the traditional technology, the application can realize the purging of the heat storage tank, realize the melting of the precipitate, or realize the effect of mixing into the main body of the fused salt.

Description

Technical Field

[0001] This invention relates to the field of molten salt energy storage technology, specifically to a molten salt thermal energy storage device and purging method with a purging function. Background Technology

[0002] Long-duration energy storage is an important direction for future new power systems, and molten salt energy storage is one of the key technological routes for long-duration energy storage. The diversified applications of molten salt thermal energy storage technology have placed new demands on the operating temperature range and performance of molten salts. For concentrated solar power (CSP), higher-temperature molten salts, such as those operating at temperatures above 650℃, are needed; for heating and steam supply, lower-temperature molten salts are required; and for the flexible retrofitting of thermal power plants, good storage / heat exchange performance must be ensured within the molten salt's operating temperature range. Therefore, the development and application of high-temperature molten salts, low-temperature molten salts, and nanoparticle molten salts are becoming increasingly urgent for various application scenarios.

[0003] However, in terms of the current application of molten salt formulations, there are still some problems that need to be solved: (1) High-temperature molten salts often have a high lower limit operating temperature and are very sensitive to ambient temperature, making them prone to local solidification or crystallization; (2) Low-temperature molten salts are prone to the presence of a small amount of solid crystals at the critical lower limit operating temperature; (3) Nanoparticle molten salts will experience agglomeration and precipitation of nanoparticles after long-term use, affecting heat storage performance. The aforementioned phenomena are very likely to occur in molten salt storage tanks, especially low-temperature molten salt storage tanks.

[0004] In addition, existing electric heat tracing technology for storage tanks often fails to reach the bottom of the tank when the electric heat tracing cable is wrapped around the outside of the tank wall or inserted into the tank. When molten salt settles at the bottom of the tank, the heating effect provided by the electric heat tracing in the bottom area may be insignificant, resulting in a low temperature in the bottom area and failure to achieve sufficient melting of the molten salt.

[0005] Although some existing technologies have attempted to treat precipitates, the problem remains that the molten salt treatment mode is too simplistic and the treatment effect is not good. Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] To address the problem of ineffective treatment of solid precipitates and crystallization in molten salt storage tanks using traditional technologies, this invention provides a molten salt thermal storage device and purging method with a purging function. This device can purge the inside of the thermal storage tank, melt the precipitates, or mix them into the molten salt body, thus eliminating the problem of localized precipitation accumulation that leads to a decline in molten salt performance.

[0008] Technical solution

[0009] To solve the above problems, the technical solution provided by the present invention is as follows:

[0010] A molten salt thermal storage device with a purging function includes a thermal storage tank. A corrugated plate is installed inside the thermal storage tank. The corrugated plate and the bottom area of ​​the thermal storage tank form a purging zone, and the corrugated plate and the upper area of ​​the thermal storage tank form a main thermal storage zone. The corrugated plate is composed of adjacent and continuous arched and concave portions. The arched portions facing the purging zone form a mixing zone. Through holes are provided on the corrugated plate, one end of which communicates with the mixing zone, and the other end of which communicates with the main thermal storage zone. At least one flow channel is provided inside the thermal storage tank. One end of the device extends through the corrugated plate to the bottom of the thermal storage tank; it also includes a bypass pipe, a bypass pump, a heater, an air compressor, and a controller; one end of the bypass pipe is connected to the main thermal storage area, and the other end of the bypass pipe is connected to the heater; the bypass pump is installed on the bypass pipe; the heater and the air compressor are both connected to the other end of the flow channel; a first switching valve is installed on the connection path between the heater and the flow channel; a second switching valve is installed on the connection path between the air compressor and the flow channel; the controller is electrically connected to the bypass pump, the heater, and the air compressor.

[0011] Optionally, the height of the end of the through hole that connects to the mixing zone is higher than the height of the end of the through hole that connects to the main thermal storage zone.

[0012] Optionally, buffer tanks are provided on both the communication path between the heater and the flow channel and the communication path between the air compressor and the flow channel, with the first switching valve located between the heater and the buffer tank and the second switching valve located between the air compressor and the buffer tank.

[0013] Optionally, the flow channel is provided with a jet nozzle on the side facing the bottom of the heat storage tank, and the outlet size of the jet nozzle is smaller than the flow channel size.

[0014] Optionally, the flow channel is configured to fit the inner wall of the thermal storage tank.

[0015] Optionally, the bottom of the heat storage tank is a concave arc shape.

[0016] Optionally, the heater and the flow channel, as well as the air compressor and the flow channel, are connected by pressure pipelines.

[0017] Optionally, it also includes an inlet pipe and an outlet pipe, one end of which is connected to the interior of the thermal storage tank.

[0018] A purging method utilizes the aforementioned molten salt thermal storage device with purging function. When molten salt purging is used, the controller starts the bypass pump while the air compressor remains off. The liquid molten salt in the main thermal storage area enters the heater and is heated. When the molten salt in the heater is heated to a temperature higher than that of the molten salt in the main thermal storage area, the first switch valve is opened until the purging of the molten salt sediment at the bottom of the thermal storage tank is completed, and then the bypass pump and the first switch valve are closed. When compressed air purging is used, the controller starts the air compressor while the bypass pump remains off, the first switch valve is closed, and the second switch valve is opened until the purging of the molten salt sediment at the bottom of the thermal storage tank is completed, and then the air compressor and the second switch valve are closed.

[0019] Beneficial effects

[0020] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0021] In view of the technical problem that traditional technologies are not effective in treating solid precipitates and crystallization in molten salt storage tanks, this invention can achieve purging inside the heat storage tank, melting the precipitates or mixing them into the molten salt body, thus eliminating the problem of localized precipitation accumulation that leads to a decline in molten salt performance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a molten salt thermal storage device with a purging function proposed in an embodiment of the present invention. Detailed Implementation

[0023] To further understand the content of this invention, a detailed description of the invention will be provided in conjunction with the accompanying drawings and embodiments.

[0024] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings. The terms "first," "second," etc., used in this invention are for the convenience of describing the technical solutions of the invention and have no specific limiting effect; they are all general terms and do not constitute a limitation on the technical solutions of the invention. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other. In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, not to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Multiple technical solutions in the same embodiment, as well as multiple technical solutions in different embodiments, can be arranged and combined to form new technical solutions that do not contradict or conflict, all of which are within the scope of protection claimed by this invention.

[0025] Example 1

[0026] Combined with appendix Figure 1This embodiment proposes a molten salt thermal storage device with a purging function, including a thermal storage tank 100. A corrugated plate 120 is provided inside the thermal storage tank 100. The corrugated plate 120 and the bottom area of ​​the thermal storage tank 100 form a purging zone 201, and the corrugated plate 120 and the upper area of ​​the thermal storage tank 100 form a main thermal storage zone 202. The corrugated plate 120 is composed of adjacent and continuous arched portions 122 and concave portions 123. The arched portions 122 facing the purging zone 201 form a mixing zone 204. A through hole 121 is provided on the corrugated plate 120. One end of the through hole 121 communicates with the mixing zone 204, and the other end of the through hole 121 communicates with the main thermal storage zone 202. At least one flow channel 105 is provided inside the thermal storage tank 100. One end of the channel 105 extends through the corrugated plate 120 to the bottom of the heat storage tank 100; it also includes a bypass pipe 101, a bypass pump 102, a heater 103, an air compressor 104, and a controller; one end of the bypass pipe 101 is connected to the main heat storage area 202, and the other end of the bypass pipe 101 is connected to the heater 103; the bypass pump 102 is installed on the bypass pipe 101; the heater 103 and the air compressor 104 are both connected to the other end of the channel 105; a first switching valve 111 is installed on the connection path between the heater 103 and the channel 105; a second switching valve 112 is installed on the connection path between the air compressor 104 and the channel 105; and the controller is electrically connected to the bypass pump 102, the heater 103, and the air compressor 104.

[0027] This embodiment provides a molten salt thermal storage device with a purging function, which can purge the inside of the thermal storage tank 100 to achieve the effect of melting the precipitate or mixing it into the molten salt body, thereby eliminating the problem of local precipitation accumulation that leads to a decrease in the performance of the molten salt.

[0028] This embodiment of a molten salt thermal storage device with a purging function includes two operating modes: molten salt purging and compressed air purging. The specific operating conditions of the two operating modes are as follows:

[0029] (1) The main working process of molten salt purging is as follows: When molten salt purging is required, the controller starts the bypass pump 102. Through the suction action of the bypass pump 102, the liquid molten salt in the heat storage tank 100 is drawn into the bypass suction pipe 101. The drawn liquid molten salt enters the heater 103. When the heater 103 heats the drawn liquid molten salt to a temperature higher than that of the molten salt in the heat storage tank 100, the first switch valve 111 is opened and the second switch valve 112 is kept closed. The heated molten salt flows out from the first switch valve 111 and flows through the flow channel 105 to the bottom of the heat storage tank 100.

[0030] Due to the operation of the bypass pump 102, the heated molten salt maintains a certain pressure during its flow. The heated molten salt is ejected from the outlet of the flow channel 105, impacting the bottom area of ​​the heat storage tank 100. This causes the sediment at the bottom of the heat storage tank 100 to be stirred up, and the heated molten salt mixes rapidly with the precipitated molten salt. Since the molten salt flowing into the flow channel 105 is heated, its temperature is higher than that of the molten salt inside the heat storage tank 100. This allows the molten salt at the bottom, which is at a lower temperature due to the thermocline, to melt rapidly. Thus, based on the stirring up of the sediment and the fact that the temperature of the heated molten salt being extracted is higher than that of the molten salt inside the heat storage tank 100, the molten salt at the bottom is melted. Due to the through-hole 121, the remelted molten salt can flow into the main heat storage area 202 through the through-hole 121 and re-participate in the subsequent system heat storage / heat release process.

[0031] (2) Compressed air purging: The main workflow is as follows: When compressed air purging is required, the controller starts the air compressor 104 to draw in ambient air, while simultaneously opening the second switch valve 112 and keeping the first switch valve 111 closed. The drawn-in compressed air flows through the flow channel 105 into the bottom area of ​​the heat storage tank 100. The sediment at the bottom of the heat storage tank 100 is impacted and lifted upwards, thus mixing with the remaining molten salt in the heat storage tank 100, thereby melting the molten salt at the bottom. Similar to the above molten salt purging workflow, due to the setting of the through hole 121, the remelted molten salt can flow into the main heat storage area 202 through the through hole 121 and re-participate in the subsequent system heat storage / heat release process.

[0032] As can be conceived, the two purging modes allow for switching between different operating conditions. When the ambient temperature is high and the temperature inside the heat storage tank 100 is stable, compressed air purging can be used. This method is simple to operate and not only melts the bottom sediment but also mixes the molten salt in the upper and lower regions of the heat storage tank 100, ensuring uniform molten salt temperature within the tank. When the ambient temperature is low and temperature stratification in the heat storage tank 100 is significant, molten salt purging can be used. This ensures a higher temperature uniformity within the tank and allows for rapid melting of the bottom sediment, ensuring safe operation.

[0033] In this embodiment, based on the above workflow, the corrugated plate 120 divides the heat storage tank 100 into two parts: the corrugated plate 120 and the bottom area of ​​the heat storage tank 100 constitute the purging zone 201, and the corrugated plate 120 and the upper area of ​​the heat storage tank 100 constitute the main heat storage zone 202. The main heat storage zone 202 primarily contains molten salt with a stable temperature, while the purging zone 201 is an area where molten salt precipitation is likely to occur, requiring purging of the precipitated molten salt.

[0034] In this embodiment, the corrugated plate 120 realizes the setting of the purging zone 201, the main heat storage zone 202, and the mixing zone 204, achieving several beneficial effects:

[0035] First, when airflow or molten salt rushes out from the outlet of flow channel 105, it can ensure that the turbulence area is mainly concentrated in the bottom area of ​​the heat storage tank 100. On the one hand, this can make the purging effect better, and on the other hand, it can prevent the turbulence area from extending to the middle and upper part of the heat storage tank 100, thereby ensuring the structural stability of the heat storage tank 100.

[0036] Secondly, the mixed flow zone 204 is formed based on the structure of the corrugated plate 120, which is composed of adjacent and continuous arched parts 122 and concave parts 123, which can form a good turbulence effect. Vortex flow can be generated on the upper and lower sides of the corrugated plate 120, thereby further improving the purging effect. It is understandable that, based on the through holes 121 provided on the corrugated plate 120, compressed air or molten salt can be used to achieve free flow between the mixing zone 204 and the main heat storage zone 202. Due to the shape of the corrugated plate 120, the compressed air or molten salt will inevitably form a vortex flow. Therefore, for the molten salt on the side of the corrugated plate 120 near the purging zone 201 or in the mixing zone 204, a better purging effect can be achieved. For the molten salt on the side of the main heat storage zone 202 on the corrugated plate 120, the compressed air or molten salt flowing out from the through holes 121 will also cause disturbance, thereby ensuring that the molten salt on the side of the main heat storage zone 202 on the corrugated plate 120 does not easily settle.

[0037] Example 2

[0038] Combined with appendix Figure 1 This embodiment proposes a molten salt thermal storage device with a purging function. Based on the above embodiment, the following improvements can be made: the height of the end connecting the through-hole 121 to the mixing zone 204 is higher than the height of the end connecting the through-hole 121 to the main thermal storage zone 202. This embodiment further improves the shape of the through-hole 121. When the height of the end connecting the through-hole 121 to the purging zone 201 is higher than the height of the end connecting the through-hole 121 to the main thermal storage zone 202, the airflow or molten salt passing through the through-hole 121 in the purging zone 201 can purge from high to low onto the surface of the corrugated plate 120 located on one side of the main thermal storage zone 202, thereby forming a secondary purging of the deposits on the corrugated plate 120.

[0039] Example 3

[0040] Combined with appendix Figure 1 This embodiment proposes a molten salt thermal storage device with a purging function. Based on the above embodiment, it can be improved as follows: a buffer tank 106 is provided on the communication path between the heater 103 and the flow channel 105, and on the communication path between the air compressor 104 and the flow channel 105. The first switching valve 111 is located between the heater 103 and the buffer tank 106, and the second switching valve 112 is located between the air compressor 104 and the buffer tank 106.

[0041] In this embodiment, a buffer tank 106 is further added. The buffer tank 106 has the functions of buffering, converging and diverting, which plays a good role in ensuring the stability of molten salt or gas flow.

[0042] As can be imagined, multiple flow channels 105 can be provided. During molten salt purging, the buffer tank 106 can hold the heated molten salt. When the molten salt in the buffer tank 106 accumulates to a certain level, it can ensure that molten salt can flow out of each flow channel 105 at the same flow rate and pressure, thereby ensuring the purging effect. Similarly, for compressed air purging, the buffer tank 106 can stabilize the air pressure, thereby ensuring the airflow pressure at the outlet of each flow channel 105.

[0043] Example 4

[0044] Combined with appendix Figure 1 This embodiment proposes a molten salt thermal storage device with a purging function. Based on the above embodiment, it can be improved as follows: a jet nozzle 203 is provided on the side of the flow channel 105 facing the bottom of the thermal storage tank 100, and the outlet size of the jet nozzle 203 is smaller than the size of the flow channel 105. In this embodiment, a jet nozzle 203 is further provided at the outlet of the flow channel 105, and the outlet size of the jet nozzle 203 is smaller than the size of the flow channel 105. The arrangement of the jet nozzle 203 allows for a higher pressure of the molten salt or gas flow at the outlet of the flow channel 105, making it easier to impact the sediment at the bottom of the thermal storage tank 100.

[0045] Example 5

[0046] Combined with appendix Figure 1 This embodiment proposes a molten salt thermal storage device with a purging function. Based on the above embodiment, it can be improved as follows: the flow channel 105 is configured to fit flush against the inner wall of the thermal storage tank 100. This embodiment is a preferred configuration of the flow channel 105. The flow channel 105's flush against the inner wall of the thermal storage tank 100 allows molten salt or gas to impact the center of the thermal storage tank 100 from the bottom edge, thereby achieving a better purging effect on the precipitates.

[0047] Example 6

[0048] Combined with appendix Figure 1This embodiment proposes a molten salt thermal storage device with a purging function. Based on the above embodiment, the following improvement can be made: the bottom of the thermal storage tank 100 is a concave arc shape. This embodiment is a preferred configuration of the shape of the thermal storage tank 100. In this embodiment, the bottom surface of the thermal storage tank 100 is a concave arc shape. On the one hand, for precipitates, the precipitated molten salt is more likely to accumulate at the lowest point of the concave arc, effectively collecting and aggregating the precipitates, making the purging more targeted. On the other hand, it also allows the airflow or molten salt flow within the flow channel 105 to form vortices, thereby further facilitating the purging of precipitates at the bottom of the thermal storage tank 100.

[0049] Example 7

[0050] Combined with appendix Figure 1 This embodiment proposes a molten salt thermal storage device with a purging function. Based on the above embodiment, it can be improved as follows: the heater 103 and the flow channel 105, and the air compressor 104 and the flow channel 105 are connected by a pressure pipe 107.

[0051] Example 8

[0052] Combined with appendix Figure 1 This embodiment proposes a molten salt thermal storage device with a purging function. Based on the above embodiment, it can be improved as follows: it further includes an inlet pipe 108 and an outlet pipe 109, one end of which is connected to the interior of the thermal storage tank 100. In this embodiment, the inlet pipe 108 and outlet pipe 109 enable the thermal storage tank 100 to connect with the rest of the thermal storage system, allowing the thermal storage tank 100 to participate in subsequent system thermal storage and release processes.

[0053] Example 9

[0054] Combined with appendix Figure 1 This embodiment proposes a purging method. Utilizing the aforementioned molten salt thermal storage device with purging function, when molten salt purging is used, the controller starts the bypass pump 102, while the air compressor 104 remains closed. The liquid molten salt in the main thermal storage zone 202 enters the heater 103 and is heated. When the molten salt in the heater 103 is heated to a temperature higher than that of the molten salt in the main thermal storage zone 202, the first switch valve 111 is opened until the molten salt at the bottom of the thermal storage tank 100 is purged, and then the bypass pump 102 and the first switch valve 111 are closed. When compressed air purging is used, the controller starts the air compressor 104, while the bypass pump 102 remains closed. The first switch valve 111 is closed, and the second switch valve 112 is opened until the molten salt at the bottom of the thermal storage tank 100 is purged, and then the air compressor 104 and the second switch valve 112 are closed.

[0055] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A molten salt thermal storage device with a purging function, characterized in that, The device includes a thermal storage tank, inside which a corrugated plate is installed. The corrugated plate and the bottom area of ​​the thermal storage tank form a purging zone, and the corrugated plate and the upper area of ​​the thermal storage tank form a main thermal storage zone. The corrugated plate is composed of adjacent and continuous arched and concave portions, and the arched portions facing the purging zone form a mixing zone. The corrugated plate is provided with through holes, one end of which communicates with the mixing zone, and the other end of which communicates with the main thermal storage zone. At least one flow channel is provided inside the thermal storage tank, and one end of the flow channel extends through the corrugated plate to the bottom of the thermal storage tank. It also includes a bypass pipe, a bypass pump, a heater, an air compressor, and a controller; one end of the bypass pipe is connected to the main heat storage area, and the other end of the bypass pipe is connected to the heater; the bypass pump is installed on the bypass pipe; the heater and the air compressor are both connected to the other end of the flow channel; a first switching valve is installed on the connection path between the heater and the flow channel; a second switching valve is installed on the connection path between the air compressor and the flow channel; and the controller is electrically connected to the bypass pump, the heater, and the air compressor.

2. The molten salt thermal storage device with purging function according to claim 1, characterized in that, The height of the end of the through hole that connects to the mixing zone is higher than the height of the end of the through hole that connects to the main thermal storage zone.

3. The molten salt thermal storage device with purging function according to claim 1, characterized in that, Buffer tanks are provided on the communication path between the heater and the flow channel, and on the communication path between the air compressor and the flow channel. The first switching valve is located between the heater and the buffer tank, and the second switching valve is located between the air compressor and the buffer tank.

4. A molten salt thermal storage device with purging function according to claim 1, characterized in that, The flow channel is provided with a jet nozzle on the side facing the bottom of the heat storage tank, and the outlet size of the jet nozzle is smaller than the flow channel size.

5. A molten salt thermal storage device with purging function according to claim 1, characterized in that, The flow channel is designed to fit the inner wall of the thermal storage tank.

6. A molten salt thermal storage device with purging function according to claim 1, characterized in that, The bottom of the heat storage tank is a concave arc shape.

7. A molten salt thermal storage device with purging function according to claim 1, characterized in that, The heater and the flow channel, as well as the air compressor and the flow channel, are connected by pressure pipes.

8. A molten salt thermal storage device with purging function according to claim 1, characterized in that, It also includes an inlet pipe and an outlet pipe, one end of which is connected to the interior of the thermal storage tank.

9. A purging method, utilizing a molten salt thermal storage device with purging function as described in any one of claims 1-8, characterized in that: When molten salt purging is used, the controller starts the bypass pump, the air compressor remains off, the liquid molten salt in the main heat storage area enters the heater and is heated, when the molten salt in the heater is heated to a temperature higher than the molten salt temperature in the main heat storage area, the first switch valve is opened until the molten salt at the bottom of the heat storage tank is purged, the bypass pump and the first switch valve are closed. When compressed air is used for purging, the controller starts the air compressor, keeps the bypass pump off, closes the first switch valve, and opens the second switch valve until the molten salt at the bottom of the heat storage tank is purged, then closes the air compressor and the second switch valve.

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