Overflow structure and fused salt heat storage heat exchanger

Abstract

The invention discloses an overflow structure and a fused salt heat storage heat exchanger, and relates to the technical field of fused salt energy storage, the overflow structure comprises an overflow unit, the overflow unit comprises an upper overflow pipeline, a lower overflow pipeline arranged in the upper overflow pipeline, and a connecting pipeline arranged at the bottom of the lower overflow pipeline; the upper overflow pipeline comprises an outer sleeve and an inner sleeve arranged in the outer sleeve; a flowing channel is formed between the inner sleeve and the outer sleeve, the distance of the flowing channel in the height direction is H3, and the working condition requirements of different flow rates of the corresponding fused salt can be met by changing the value of H3. The upper overflow pipeline with a certain length can ensure that the fused salt has enough retention time in the heat exchanger, so that a medium in the heat exchange pipeline can fully exchange heat, and the problem that the fused salt is frozen and blocked in the overflow unit can be effectively prevented.

Description

Technical Field

[0001] The present invention relates to the field of molten salt energy storage, and in particular to an overflow structure and a molten salt heat storage heat exchanger. Background Art

[0002] Energy storage technology can adjust the power supply system at any time with its functions of peak shaving, frequency modulation and energy backup, achieving the effect of "peak shaving and valley filling"; compared with electrochemical energy storage and other methods, heat storage technology has many advantages such as small floor area, small environmental impact, and being unrestricted by geographical and environmental conditions.

[0003] Due to the excellent electrical conductivity, thermal stability and large specific heat capacity of molten salt, molten salt heat storage technology occupies a relatively high proportion in the field of heat storage and has great energy storage advantages; as a technical method to realize molten salt heat storage, the molten salt steam heat exchanger uses the off-peak electricity at night of a thermal power unit to heat molten salt for energy storage, and then uses the heat exchanger to convert the stored heat energy into high-quality heat source - steam, so as to realize the conversion of off-peak electricity at night from "storage" to "use".

[0004] In the process of converting the heat energy stored in molten salt into steam by using a heat exchanger, due to the high melting point of molten salt, the high-temperature molten salt flows inside the heat exchanger, and it is very easy to encounter freezing blockage of molten salt due to the design, operation and condition change adjustment of the steam generator. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is that the existing molten rock energy storage heat exchanger is prone to freezing blockage during operation.

[0006] The above technical problem is solved by the following technical solution: The present invention provides an overflow structure, which includes an overflow unit, including an upper overflow pipe, a lower overflow pipe arranged inside the upper overflow pipe, and a connecting pipe arranged at the bottom of the lower overflow pipe;

[0007] The upper overflow pipe includes an outer sleeve and an inner sleeve arranged inside the outer sleeve;

[0008] A flow channel is formed between the inner sleeve and the outer sleeve, and the height direction distance of the flow channel is H3. By changing the value of H3, the working condition requirements of different molten salt flow rates can be met.

[0009] In a preferred embodiment of the overflow structure of the present invention: an overflow outlet for communicating with the outer sleeve is provided at the top position of the inner sleeve, and an overflow inlet exists between the bottom of the outer sleeve and the inner sleeve;

[0010] The inner sleeve is communicated with the flow channel through the overflow outlet.

[0011] In a preferred embodiment of the overflow structure of the present invention: the lower overflow pipe is adapted to the inner sleeve, and an interference fit is provided between the lower overflow pipe and the inner sleeve.

[0012] In a preferred embodiment of the overflow structure of the present invention: the number of the overflow units is multiple groups, and the multiple groups of overflow units are arranged in an array at the bottom of the storage box;

[0013] The storage box is provided with layers, and the molten salt inside the upper storage box enters the inside of the lower storage box through the overflow unit.

[0014] In a preferred embodiment of the overflow structure of the present invention: the connecting pipe penetrates into the inside of the lower layer storage box, and two adjacent connecting pipes are arranged at different heights, so as to realize the layered entry of the molten salt in the upper layer into the inside of the storage box.

[0015] In a preferred embodiment of the overflow structure of the present invention: multiple groups of the connecting pipes are distributed in a stepped shape along the horizontal direction, so as to realize that the molten lava enters the lower layer storage box at different height positions along the bottom of the connecting pipe.

[0016] The beneficial effect of the present invention is that: the overflow unit has an upper overflow pipe with a certain length inside the upper storage box, which can ensure that the molten salt has enough residence time inside the heat exchanger; at the same time, after the molten salt enters the overflow unit through the overflow inlet and passes through the upper overflow pipe, the molten salt inside the storage box can still heat the molten salt flowing inside the overflow unit, which can prevent excessive heat loss of the molten salt during the flow between different storage boxes, and at the same time prevent the problem of freezing and blocking of the molten salt inside the overflow unit.

[0017] Therefore, the technical problem to be solved by the present invention is that: during the heat exchange process, due to the horizontal arrangement of the heat exchange tubes, the temperature of the working medium inside the tubes on the inlet side of the heat exchange tubes is relatively low, and the heat absorption is relatively large. The outlet side of the heat exchange tubes is superheated steam with a relatively high temperature and relatively little heat absorption, resulting in uneven lateral temperature distribution of the molten salt during flow in the module and uneven heating of the heat exchange tubes.

[0018] The above technical problem is solved by the following technical solution: the present invention provides a molten salt heat storage heat exchanger, which includes heat exchange tubes, and the heat exchange tubes are arranged inside the storage box;

[0019] The overflow unit is arranged at the middle position of the heat exchange tubes.

[0020] In a preferred embodiment of the molten salt heat storage heat exchanger of the present invention: there is a height difference H1 between the highest liquid level inside the inner sleeve and the highest liquid level inside the heat exchange tubes, and H1 is a positive number;

[0021] The molten lava level inside the storage tank is higher than the liquid level inside the heat exchange tube, enabling sufficient heating of the solute inside the heat exchange tube.

[0022] In a preferred embodiment of the molten salt thermal energy storage heat exchanger of the present invention: there is a height difference H2 between the highest liquid level inside the inner sleeve and the highest liquid level inside the heat exchange tube, and H2 is negative;

[0023] The molten lava inside the upper storage tank can flow quickly into the lower storage tank.

[0024] The beneficial effects of the present invention are as follows: The overflow unit has an upper overflow pipe of a certain length inside the upper storage tank, which can ensure sufficient residence time of the molten salt inside the heat exchanger; at the same time, after the molten salt enters the overflow unit through the overflow inlet and passes through the upper overflow pipe, the molten salt inside the storage tank can still heat the molten salt flowing inside the overflow unit, which can prevent excessive heat loss when the molten salt flows between different storage tanks and prevent the problem of frozen blockage of the molten salt inside the overflow unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present invention and do not limit the present invention. Among them:

[0026] Figure 1 Shows a schematic structural diagram of the overflow unit;

[0027] Figure 2 Shows a schematic structural diagram of the heat exchanger;

[0028] Figure 3 Shows a schematic diagram of the adjacent staggered structure of the connecting pipes;

[0029] Figure 4 Shows Figure 3 A local enlarged view at location A of;

[0030] Figure 5 Shows a schematic diagram of the stepped arrangement structure of the connecting pipes;

[0031] Figure 6 Shows a schematic diagram of the connection structure between the overflow unit and the heat exchange tube. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below in conjunction with the specific embodiments and the drawings.

[0033] The terms used in the present invention are those general terms that are currently widely used in the art in consideration of the functions of the present invention. However, these terms may vary according to the intentions of those of ordinary skill in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in such cases, their detailed meanings will be described in the detailed description of the present invention. Therefore, the terms used in the specification should not be understood as simple names, but based on the meanings of the terms and the overall description of the present invention.

[0034] Referring to Figure 1 and Figures 3 to 5 , this embodiment provides an overflow structure, including an overflow unit 1, which includes an upper overflow pipe 11, a lower overflow pipe 12, and a connecting pipe 13. The upper overflow pipe 11 includes an outer sleeve 111 and an inner sleeve 112 disposed inside the outer sleeve 111; a flow channel L is formed between the inner sleeve 112 and the outer sleeve 111, and the height direction distance of the flow channel L is H3. By changing the value of H3, the working condition requirements corresponding to different flow rates of molten salt can be met.

[0035] By arranging the upper overflow pipe with a certain length of the overflow unit 1 inside the upper storage box 2, it can ensure that the molten salt has sufficient residence time inside the storage box. At the same time, after the molten salt enters the gap between the outer sleeve 111 and the inner sleeve 112 through the overflow inlet, it enters the inside of the lower overflow pipe 12 through the gap between the outer sleeve 111 and the inner sleeve 112.

[0036] When a flow channel L is formed between the inner sleeve 112 and the outer sleeve 111, the height H3 of the flow channel L determines the time of the molten salt inside the storage box 2. When the value of H3 is relatively large, the molten salt inside the upper storage box 2 enters the lower storage box 2 through the overflow unit 1; during this process, the molten salt located inside the upper storage box 2 will still heat the molten salt flowing inside the overflow unit, preventing the problem of frozen blockage of the molten salt inside the overflow unit 1.

[0037] When the flow rate of the molten salt entering the upper storage box 2 is relatively large, the height H3 of the flow channel L can be changed. When the value of H3 is relatively short, a shorter H3 is used to avoid the situation of the molten salt overflowing from inside the storage box 2.

[0038] When the flow rate of the molten salt is small and the risk of the molten salt overflowing is low, the length of the upper overflow pipe can be increased to control the capacity inside the molten salt heat storage and heat exchange module, ensure the sufficient liquid level height of the molten salt, and ensure the normal progress of the entire heat exchange process.

[0039] As an alternative embodiment, an overflow outlet O for communicating with the outer sleeve 111 is provided at the top position of the inner sleeve 112, and an overflow inlet K exists between the bottom of the outer sleeve 111 and the inner sleeve 112; the inner sleeve 112 is communicated with the flow channel L through the overflow outlet O.

[0040] In this embodiment, the outer sleeve 111 and the inner sleeve 112 are fixedly welded, the overflow outlet O is provided at the top position of the inner sleeve 112, and the molten salt passes through the overflow inlet K opened between the outer sleeve 111 and the inner sleeve 112, and the molten salt enters the inside of the flow channel L through the overflow inlet K.

[0041] The molten salt located inside the storage box 2 enters the inside of the overflow channel L through the overflow inlet K at the bottom, and then as the molten salt inside the storage box 2 gradually increases, the liquid level height of the molten salt gradually increases; when the height position of the molten salt is flush with the overflow outlet O, the molten salt located inside the flow channel L enters the inner wall of the inner sleeve 112 through the overflow outlet O, and then enters the lower overflow pipe 12, and then enters the lower-layer storage box 2 through the lower overflow pipe 12.

[0042] In an embodiment provided by the present application, the lower overflow pipe 12 is adapted to the inner sleeve 112, and an interference fit is provided between the lower overflow pipe 12 and the inner sleeve 112.

[0043] In this embodiment, the lower overflow pipe 12 is connected to the connecting pipe 13, and the lower overflow pipe 12 and the connecting pipe 13 can be cast by an integral molding method; the distance that the connecting pipe 13 penetrates into the lower-layer storage box 2 determines the height position where the upper-layer molten salt flows into the lower-layer storage box 2.

[0044] In order to meet different working conditions and ensure that the molten salt can be sufficiently stable and uniform during the process of entering the lower-layer storage box 2, and to stably and uniformly heat the heat exchange tube 3 inside the lower-layer storage box 2, the length of the connecting pipe 13 can be controlled to ensure that the molten salt enters the storage box 2, thereby realizing the uniform temperature of the molten salt inside the lower-layer storage box 2.

[0045] In some embodiments, the number of the overflow units 1 is multiple groups, and the multiple groups of overflow units 1 are arranged in an array at the bottom of the storage box 2; the storage box 2 is provided in layers, and the molten salt inside the upper-layer storage box 2 enters the lower-layer storage box 2 through the overflow unit 1.

[0046] In this embodiment, the number of the overflow units 1 is multiple groups, and the multiple groups of overflow units 1 are distributed in an array along the horizontal direction; the overflow unit 1 is provided at the bottom position of the storage box 2, 11 is located inside the upper-layer storage box 2; 12 penetrates through the upper-layer storage box 2 and extends into the lower-layer storage box 2.

[0047] The molten salt inside the upper storage box 2 enters the overflow channel L through the overflow inlet K, and then flows to the inner wall pipe of the inner sleeve 112 through the overflow outlet O; then enters the lower overflow pipe 12 through the inner sleeve 112, and finally flows to the lower storage box 2 through the connecting pipe 13.

[0048] It should be noted that the entire storage box 2 is filled with heat storage particles, and the filling amount of the heat storage particles is 80% to 90% of the effective volume of the storage box 2; when working, the molten salt flow inside the storage box 2 is large and the flow is slow, so the internal heat exchange tubes are usually arranged in a horizontal row.

[0049] The overflow inlet of the upper storage box 2 is connected to the liquid inlet of the lower storage box. The bottom layer of the heat exchanger is provided with a solid heat storage module, and the overflow inlet of the fixed heat storage module is connected to the inlet of the liquid storage module.

[0050] The overflow unit is composed of an upper overflow pipe, a lower overflow pipe and a connecting pipe. When the heat exchanger is working, the molten salt flows to the bottom of the storage box 2 after heat exchange with the heat exchange tube 3. The molten salt enters the upper overflow pipe through the overflow inlet at the bottom of the overflow unit, and then enters the lower storage box 2 through connecting pipes 13 of different lengths, ensuring that the molten salt flows between continuous storage boxes 2.

[0051] Reference Figure 1 This embodiment provides a molten salt heat storage heat exchanger, including a heat exchange tube 3, which is arranged inside a storage box 2; and an overflow unit 1 is arranged in the center of the heat exchange tube 3.

[0052] In this embodiment, the heat exchange tube 3 inside the heat exchanger is preferably a serpentine heat exchange tube. The serpentine heat exchange tube has the advantage of a large heat exchange area. There are four serpentine heat exchange tubes arranged from top to bottom inside the storage box 2, arranged in parallel in horizontal rows, and there is a certain tube spacing from top to bottom.

[0053] refer to Figure 5 As an optional embodiment, there is a height difference H1 between the highest liquid level inside the inner sleeve 112 and the highest liquid level inside the heat exchange tube 3, and H1 is a positive number; the lava liquid level inside the storage box 2 is higher than the liquid level of the heat exchange tube 3, so that the solute inside the heat exchange tube 3 is fully heated.

[0054] In this embodiment, the highest liquid level position of the overflow outlet O opened on the inner wall of the inner sleeve 112 is higher than or equal to the highest liquid level inside the heat exchange tube 3; when the molten salt enters the storage box 2, it needs to pass through the overflow unit 1 to enter the bottom storage box 2, and the height position of the overflow outlet O determines the liquid level height of the molten salt inside the storage box 2.

[0055] When H1 is a positive number, the storage tank 2 has a relatively long upper overflow pipe, which can ensure that the molten salt has sufficient residence time inside the storage tank 2. At the same time, after the molten salt enters the overflow channel L through the overflow inlet K and passes through the upper overflow pipe, the molten salt inside the storage tank 2 will still heat the molten salt flowing inside the overflow unit 1, preventing the problem of frozen blockage of the molten salt inside the overflow structure.

[0056] Reference Figure 6 , in an embodiment provided by the present application, there is a height difference H2 between the highest liquid level inside the inner sleeve 112 and the highest liquid level inside the heat exchange tube 3, and H2 is a negative number; the molten lava inside the upper storage tank 2 can flow quickly into the lower storage tank 2.

[0057] In this embodiment, the highest liquid level position of the overflow outlet O opened at the top of the inner sleeve 112 is lower than the position of the highest liquid level inside the heat exchange tube 3, and the distance from the bottom of the overflow channel L is relatively low, so that the molten salt entering the storage tank 2 can quickly enter the lower storage tank 2 through the overflow unit 1.

[0058] In order to meet different working conditions of the heat exchanger, when the molten salt flow rate is large, the length of the upper overflow pipe can be selected to be shortened, and the length of the overflow channel L can be shortened to shorten the residence time of the molten salt in the overflow unit 1; furthermore, the situation of the molten salt overflowing from the storage tank 2 can be avoided.

[0059] When the molten salt flow rate is small and the risk of molten salt overflow is low, the length of the upper overflow pipe can be increased to control the capacity inside the storage tank 2, ensure a sufficient liquid level height of the molten salt, so that the molten salt can fully exchange heat with the medium inside the heat exchange pipe, and ensure the normal progress of the entire heat exchange process.

[0060] Reference Figure 3 , in some embodiments, the connecting pipe 13 penetrates into the lower storage tank 2, and adjacent two groups of connecting pipes 13 are arranged in a staggered manner up and down, so as to realize the layered entry of the upper molten salt into the storage tank.

[0061] In this embodiment, the lengths of the connecting pipes 13 arranged at the bottoms of adjacent two groups of overflow units 1 adopt a structure with different lengths; the lengths of the two groups of connecting pipes 13 cooperate with each other, one long and one short, so that the height position of the molten salt inside the upper storage tank 2 entering the lower storage tank 2 can be effectively distinguished, and thus the temperature of the molten salt inside the lower storage tank 2 can be more uniform.

[0062] By setting connection pipes 13 with different lengths at intervals, while ensuring the heat required for the serpentine heat exchange pipes inside the upper storage box 2, the molten salt in the upper layer can be directly transported to different height layers inside the lower storage box 2, and mixed with the molten salt located inside the lower storage box 2, further improving the temperature uniformity of the molten salt inside the storage box 2.

[0063] Reference Figure 5 , in an embodiment provided by the present application, a plurality of groups of connection pipes 13 are distributed in a stepped manner along the horizontal direction, thereby realizing that the lava enters the lower storage box 2 at different height positions along the bottom of the connection pipes 13.

[0064] In this embodiment, for the vertical pipe spacing between the serpentine heat exchange pipes, connection pipes 13 with different lengths are designed. By placing the outlet of the connection pipe 13 near the inlet of the heat exchange pipe; the heat absorption is relatively large near the medium inlet position of the heat exchange pipe, and then different connection pipes need to correspond to the outlet positions of different heat exchange pipes 3; this enables the molten salt with the same relatively high initial temperature to exchange heat with the inlet working medium of multiple serpentine heat exchange pipes, meeting the large amount of heat required for the inlet part of the heat exchange pipes; at the same time, the working medium in multiple serpentine heat exchange pipes can be raised to a relatively high temperature, and when exchanging heat with the subsequent flowing molten salt, the difference in heat absorption at different positions is reduced.

[0065] During the heat exchange process, due to the horizontal arrangement of the heat exchange pipes, the temperature of the working medium inside the pipes on the inlet side of the heat exchange pipes is relatively low and the heat absorption is large, while the outlet side of the heat exchange pipes is superheated steam with a relatively high temperature and less heat absorption. The multiple groups of connection pipes 13 are arranged in a stepped manner, which can better conduct heat exchange for the heat exchange pipes 3 arranged in layers.

[0066] Finally, it should be noted that the methods and devices described in detail above are only embodiments, and those skilled in the art can modify these embodiments in different ways as long as they do not depart from the scope of the present invention.

[0067] Importantly, 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 preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. An overflow structure, characterized in that: including, an overflow unit (1), comprising an upper overflow pipe (11), a lower overflow pipe (12) disposed inside the upper overflow pipe (11), and a connecting pipe (13) disposed at the bottom of the lower overflow pipe (12); the upper overflow pipe (11) includes an outer sleeve (111) and an inner sleeve (112) disposed inside the outer sleeve (111); a flow channel is formed between the inner sleeve (112) and the outer sleeve (111), and the height direction distance of the flow channel is H3. By changing the value of H3, the working condition requirements for different flow rates of the corresponding molten salt can be met.

2. The overflow structure according to claim 1, wherein: an overflow outlet for communicating with the outer sleeve (111) is provided at the top position of the inner sleeve (112), and an overflow inlet exists between the bottom of the outer sleeve (111) and the inner sleeve (112); the inner sleeve (112) is communicated with the flow channel through the overflow outlet.

3. The overflow structure according to claim 2, wherein: the lower overflow pipe (12) is adapted to the inner sleeve (112), and an interference fit is provided between the lower overflow pipe (12) and the inner sleeve (112).

4. The overflow structure according to claim 3, wherein: the number of the overflow units (1) is multiple groups, and the multiple groups of overflow units (1) are arranged in an array at the bottom of the storage box body; the storage box body is arranged in layers, and the molten salt inside the upper storage box body enters the lower storage box body through the overflow unit (1).

5. The overflow structure according to any one of claims 1 to 4, wherein: the connecting pipe (13) penetrates into the inner part of the lower layer storage box body, and the heights of adjacent two groups of connecting pipes (13) are arranged in a staggered manner, so as to realize the layered entry of the upper layer molten salt into the storage box body.

6. The overflow structure according to any one of claims 1 to 4, wherein: multiple groups of the connecting pipes (13) are distributed in a stepped manner along the horizontal direction, so as to realize that the lava enters the lower layer storage box body at different height positions along the bottom of the connecting pipe (13).

7. A molten salt thermal energy storage heat exchanger, characterized in that: including the overflow structure according to any one of claims 1 to 4, and, a heat exchange tube (3), the heat exchange tube (3) is disposed inside the storage box body; the overflow unit (1) is disposed at the middle position of the heat exchange tube (3).

8. The molten salt heat storage heat exchanger according to claim 7, wherein: a height difference H1 exists between the highest liquid level inside the inner sleeve (112) and the highest liquid level inside the heat exchange tube (3), and H1 is a positive number; the molten salt liquid level inside the storage box body is higher than the liquid level of the heat exchange tube (3), so as to fully heat the solute inside the heat exchange tube (3).

9. The molten salt heat storage heat exchanger according to claim 7, wherein: a height difference H2 exists between the highest liquid level inside the inner sleeve (112) and the highest liquid level inside the heat exchange tube (3), and H2 is a negative number; the molten salt inside the upper storage box body can flow quickly into the lower storage box body.

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