Fused salt heat exchanger capable of avoiding blockage

Abstract

The molten salt heat exchanger comprises a tank body, the two sides of the tank body are provided with a salt inlet allowing molten salt to enter and a salt outlet used for guiding out the molten salt, the bottom face in the tank body is provided with a lower baffle plate, the top face in the tank body is provided with an upper baffle plate, the lower baffle plate comprises a plate body, and the plate body is provided with a plurality of baffle plates. Streamlined flow guide parts are arranged on the two sides of the plate body, and the lower baffle plates and the upper baffle plates are sequentially and alternately arranged in the tank body and form a molten salt flowing path. The invention has the beneficial effects that the upper baffle plate and the lower baffle plate are provided with the streamlined flow guide parts, so that the fluid can be guided to change the direction more smoothly, and compared with a right angle or a small fillet, the local resistance loss can be obviously reduced, the areas of eddy current and a static region are reduced, the retention and accumulation of molten salt are avoided, and the stability of the molten salt is improved. And meanwhile, the design of the hyperbolic structure is also beneficial to gliding and falling of the fused salt, and local retention of the fused salt is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of molten salt heat storage, in particular to a molten salt heat exchanger capable of avoiding blockage. BACKGROUND

[0002] In a molten salt heating and heat storage system (such as a photo-thermal power generation or industrial waste heat recovery), molten salt (usually a mixture of nitrate) operates in the range of 200-565℃. When the system is shut down or local flow stagnates, the molten salt temperature drops below the freezing point (about 200℃) and phase change crystallization occurs, causing an increase in molten salt flow resistance and resulting in blockage. Due to the formation of a low-speed vortex zone behind the baffle, the residence time of the molten salt is prolonged, resulting in accelerated heat dissipation, local temperature drop and crystallization blockage. In addition, the connection between the baffle and the shell is prone to thermal bridge effect, which accelerates the cooling of the backside molten salt and also leads to the accumulation of molten salt.

[0003] In the conventional molten salt heat exchanger currently used, a salt discharge hole is generally provided at the lower part of the baffle of the horizontal container, but there is a fatal defect: if the lower part of the baffle has molten salt crystallization, the molten salt will be retained and form a "salt plug", which will block the flow process and cause local overheating and cracking when restarted.

[0004] Patent No. CN202510008342.6 discloses a horizontal single-tank molten salt heat storage system and method, which optimizes the salt discharge process and realizes 24h stable steam supply. However, it still cannot solve the problem of local accumulation of molten salt when the system is shut down. SUMMARY

[0005] The present application aims to provide a molten salt heat exchanger capable of avoiding blockage, which can prevent the problem of local accumulation of molten salt when the system is shut down, thereby improving the service life of the equipment.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: A molten salt heat exchanger capable of avoiding blockage comprises a tank body, the two sides of the tank body are respectively provided with a molten salt inlet and a molten salt outlet for discharging the molten salt therein, the bottom surface inside the tank body is provided with a lower baffle, the top surface inside the tank body is provided with an upper baffle, the lower baffle comprises a baffle body, the two sides of the baffle body have flow guiding parts in a streamline shape, and the lower baffle and the upper baffle are arranged alternately inside the tank body and form a molten salt flow path.

[0007] Preferably, the upper baffle and the lower baffle have the same structure.

[0008] Preferably, the bottom of the tank body is provided with a salt discharge hole for discharging the molten salt, and the salt discharge hole is connected with a salt discharge pipeline.

[0009] Preferably, the salt-removing opening is arranged at the joint of the flow guide and the inner wall of the tank body.

[0010] Preferably, the salt-removing pipeline is provided with a first valve for opening / closing the pipeline and a second valve for plugging / opening the salt-removing opening.

[0011] Preferably, the first valve is a pneumatic valve, and the first valve is connected with an electric control device for controlling the opening / closing of the first valve and a compressed air connection port.

[0012] Preferably, the second valve comprises a baffle for plugging the salt-removing opening, and the baffle is connected with an elastic member for lifting the baffle to open the salt-removing opening.

[0013] Preferably, the baffle has a first trapezoidal sealing surface, and the salt-removing opening has a second trapezoidal sealing surface matched with the first trapezoidal sealing surface.

[0014] Preferably, the second valve further comprises a support plate installed in the salt-removing opening, and the elastic member is located between the baffle and the support plate.

[0015] Preferably, the support plate is provided with an opening hole for the molten salt to flow out.

[0016] The application has the following beneficial effects: 1. The upper and lower baffles have flow line type flow guides, which can more smoothly guide the fluid to change direction, can significantly reduce local resistance loss, reduce the area of vortex and static region, avoid the retention and accumulation of molten salt, and the design of the hyperbolic structure also facilitates the sliding and falling of the molten salt, and reduces the local retention of the molten salt.

[0017] 2. The retention dead angle on the back side of the baffle is eliminated, the salt-removing opening is located below the back side of the baffle and below the tank body, and the molten salt is discharged along the curved surface of the baffle and the salt-removing opening in turn when the machine is stopped, thereby avoiding the retention caused by the molten salt bypassing the baffle or being discharged from the salt-removing hole below the baffle to the next stage one by one, and the discharge rate of the molten salt on the back side of the baffle is greatly improved compared with the traditional discharge method.

[0018] 3. The salt-removing opening is located at the end of the front lower baffle among the two adjacent lower baffles, and the salt-removing opening is directly connected with the external salt-removing pipeline. The bottom profiles of the two adjacent lower baffles and the inner wall of the tank body jointly form a flow guide collection groove, so that the molten salt on the back side of the baffle can directly flow into the collection groove along the curved surface thereof when the machine is stopped, and is discharged by gravity through the salt-removing opening, thereby avoiding the retention caused by the molten salt bypassing or being discharged from the salt-removing hole to the next stage one by one in the traditional design. This is the directional gravity direct discharge structure designed in the application. Compared with the traditional design, the retention time of the molten salt is greatly reduced, and the solidification risk is greatly reduced.

[0019] 4. A first valve and a second valve are connected in series on the brine evaporation pipeline. The actuator of the first valve is a fail-open type, and its control logic is based on the start and stop signals of the molten salt pump. Therefore, this application can provide safety guarantees for the following four different operating conditions: Normal shutdown: Molten salt pump stops, electrical signal disappears, first valve opens; Instrument air interruption: The first valve opens automatically due to air loss; Control signal loss / power failure: The first valve opens automatically due to power failure; Heat exchanger depressurization: The second valve opens due to depressurization and is driven by the elastic element.

[0020] 5. The salt-draining pipe is inclined in the salt-draining direction (gradually decreasing along the flow direction of the internal molten salt to facilitate salt drainage); the inclination slope of the salt-draining pipe is ≥5°, and a heat tracing wire is installed on the outside of the salt-draining pipe for full-process heat tracing to prevent secondary solidification of the molten salt during the salt-draining process. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of this application; Figure 2 This is a schematic diagram showing the installation relationship between the second valve and the salt outlet.

[0022] The accompanying drawings are for illustrative purposes only and should not be construed as limiting the scope of this patent. To better illustrate this embodiment, some components in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings. Detailed Implementation

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

[0024] Example 1 like Figure 1 As shown, this embodiment of a molten salt heat exchanger for preventing clogging includes a tank 1. The tank 1 has an inlet for molten salt to enter and an outlet for molten salt to exit (this is a conventional arrangement and is not shown in the figure). A lower baffle 2 is provided on the bottom surface inside the tank 1, and an upper baffle 7 is provided on the top surface inside the tank 1. The lower baffle 2 includes a plate 21 with streamlined guide sections 22 on both sides. The lower baffle 2 and the upper baffle 7 are arranged alternately inside the tank, forming a flow path for the molten salt (i.e.,...). Figure 1 (As indicated by the arrow in the image).

[0025] The upper baffle 7 has the same structure as the lower baffle 2, and also has a plate body and a flow guide. The baffle is designed in a hyperbolic shape to reduce the flow resistance when molten salt passes through and to reduce the area where molten salt stays on the back side of the baffle, thereby reducing the formation of "salt plugs" and facilitating salt drainage.

[0026] like Figure 1 and Figure 2 As shown, a salt drain port 11 for discharging molten salt is provided at the bottom of the tank 1, and the salt drain port 11 is connected to a salt draining pipeline.

[0027] To quickly drain the molten salt from tank 1 during system shutdown, this embodiment places a salt-draining port 11 at the connection between the flow guide 22 and the inner wall of tank 1. The salt-draining port 11 is located at the end of the foremost of two adjacent lower baffles 2 (each lower baffle 2 has two flow guides 22; the molten salt flows upward along the left flow guide 22 and downward along the right flow guide 22; the end here refers to the connection between the right flow guide 22 and the inner wall of tank 1). In this embodiment, two salt-draining ports are provided to accommodate the number of lower baffles 2.

[0028] The desalination pipeline is equipped with a first valve 4 for opening / closing the pipeline and a second valve 3 for sealing / opening the desalination port 11.

[0029] The first valve 4 is a pneumatic valve, and it is connected to an electronic control device 6 that controls its opening and closing, and a compressed air connection port 5. In this embodiment, the compressed air connection port 5 is integrated with the air compressor.

[0030] like Figure 2 As shown, the second valve 3 includes a baffle 34 for blocking the salt outlet 11, and the baffle 34 is connected to an elastic element 33 for lifting it to open the salt outlet 11.

[0031] When the molten salt heat exchanger starts up, the operating signal of the molten salt pump motor is sent to the electrical control device 6. The electrical control device 6 controls the air compressor to start, filling the air chamber of the first valve 4 with compressed air. The compressed air pressure overcomes the spring force inside the first valve 4, driving the first valve 4 to close, at which point the desalination pipeline is closed. At the same time, due to the start-up of the molten salt heat exchanger, the pressure inside the tank 1 increases, and the second valve 3 is closed under pressure, thus closing the desalination port 11 as well. When the molten salt heat exchanger stops running: the operating signal of the molten salt pump disappears, and the stop signal of the molten salt pump motor is sent to the electrical control device 6. The electrical control device 6 controls the air compressor to stop running, and the compressed air in the air chamber of the first valve 4 is quickly discharged to the atmosphere. The spring force inside the first valve 4 loses the resistance of air pressure, and the spring force drives the first valve 4 back to its initial position, at which point the desalination pipeline opens; at the same time, due to the decrease in pressure inside the tank 1, the baffle 34 in the second valve 3, under the action of its internal elastic element 33, moves upward to open the desalination port 11. Molten salt inside tank 1 flows into the collection device through two salt-draining ports 11 and a salt-draining pipeline under the action of gravity.

[0032] Both valve 4 and valve 3 are normally open valves. The use of normally open valves facilitates the inspection and maintenance of this salt-draining pipeline.

[0033] like Figure 2 As shown, the baffle 34 has a first trapezoidal sealing surface, and the salt-repellent port 11 has a second trapezoidal sealing surface that mates with the first trapezoidal sealing surface, which facilitates the sealing of the salt-repellent port 11.

[0034] The second valve 3 also includes a support plate 31 installed inside the salt outlet 11, and an elastic element 33 is located between the baffle 34 and the support plate 31. In this embodiment, the elastic element 33 is a spring.

[0035] An opening (not shown in the figure) is provided on the support plate 31 for molten salt to flow out.

[0036] In this embodiment, a guide post 32 is also provided to guide the extension and retraction of the elastic member 33. An opening is provided on the support plate 31 for the guide post 32 to move along. The top end of the guide post 32 is connected to the baffle 34. Under the elastic force of the elastic member 33, the baffle 34 and the guide post 32 can move up and down to block or open the salt-repellent port 11.

[0037] During operation, when the molten salt heat exchanger is shut down normally, the first valve 4 can be automatically opened based on the shutdown signal of the molten salt heat exchanger to achieve automatic venting. When encountering any abnormal operating conditions such as instrument air interruption or control signal loss, the first valve 4 will open malfunctionily. When the tank 1 is abnormally depressurized, the second valve 3 can also be opened independently to provide the equipment with final mechanical protection.

[0038] The above embodiments are not intended to limit the shape, material, structure, etc. of the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

[0039] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of this invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this invention.

[0040] If the terms "first" or "second" are used in this document to define components, those skilled in the art should know that the use of "first" or "second" is merely for the convenience of describing the invention and simplifying the description, and unless otherwise stated, the above terms have no special meaning.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A molten salt heat exchanger to prevent clogging, comprising a tank, wherein the tank has an inlet for molten salt to enter and an outlet for molten salt to exit, characterized in that, The bottom surface of the tank is provided with a lower baffle plate, and the top surface of the tank is provided with an upper baffle plate. The lower baffle plate includes a plate body with streamlined flow guides on both sides. The lower baffle plate and the upper baffle plate are arranged alternately inside the tank to form a flow path for the molten salt.

2. A molten salt heat exchanger for preventing clogging according to claim 1, characterized in that, The upper baffle plate has the same structure as the lower baffle plate.

3. A molten salt heat exchanger for preventing clogging according to claim 1, characterized in that, The bottom of the tank is provided with a salt drain port for discharging molten salt, and the salt drain port is connected to a salt drain pipe.

4. A molten salt heat exchanger for preventing clogging according to claim 1, characterized in that, The salt-repellent port is located at the connection between the flow guide and the inner wall of the tank.

5. A molten salt heat exchanger for preventing clogging according to claim 1, characterized in that, The desalination pipeline is equipped with a first valve for opening / closing the pipeline and a second valve for sealing / opening the desalination port.

6. A molten salt heat exchanger for preventing clogging according to claim 5, characterized in that, The first valve is a pneumatic valve, and the first valve is connected to an electrical control device for controlling its opening / closing and a compressed air connection port.

7. A molten salt heat exchanger for preventing blockage according to claim 5, characterized in that, The second valve includes a baffle for sealing the sluice gate, the baffle being connected to an elastic element for lifting it to open the sluice gate.

8. A molten salt heat exchanger for preventing clogging according to claim 7, characterized in that, The baffle has a first trapezoidal sealing surface, and the salt-repellent port has a second trapezoidal sealing surface that mates with the first trapezoidal sealing surface.

9. A molten salt heat exchanger for preventing clogging according to claim 7, characterized in that, The second valve also includes a support plate installed inside the salt outlet, with the elastic element located between the baffle and the support plate.

10. A molten salt heat exchanger for preventing clogging according to claim 9, characterized in that, The support plate has openings for molten salt to flow out.

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