Heat preservation structure and heat preservation method for heat absorber

Abstract

The invention relates to the technical field of heat preservation of photoelectric heating systems, in particular to a heat preservation structure and method for a heat absorber. The heat preservation structure sequentially comprises a first heat preservation layer, a sleeve and a second heat preservation layer from inside to outside. The first heat preservation layer comprises a heat preservation layer body and a heat preservation ring, an annular step is arranged on the top of the heat preservation layer body, and the heat preservation ring capable of moving up and down is arranged on the annular step. After being heated and expanded, the pipeline drives the heat-preservation layer body to move downwards along the inner wall of the sleeve, and the heat-preservation ring moves upwards along the inner wall of the sleeve until a gap between the heat-preservation layer body and the bottom of the heat-preservation box is shielded. A pressed sealing ring is arranged between the second heat preservation layer and the heat preservation layer body. According to the technical scheme, the problems that in the operation process of the heat absorber, the salt dredging pipeline makes direct contact with outside air after being heated and expanded, so that local heat dissipation is large, fused salt is prone to solidification, and even freezing blockage and pipe explosion are caused can be solved, and the important safety production significance is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation for solar thermal power generation systems, and particularly to a thermal insulation structure and method for an absorber. Background Art

[0002] When a tower-type solar thermal power generation system uses a binary nitrate molten salt composed of 60% sodium nitrate and 40% potassium nitrate as a heat transfer working fluid, the operating temperature of the heat absorption system is controlled between 290°C and 565°C. This temperature range is to ensure that the molten salt can transfer heat effectively and stably. However, if the thermal insulation measures for the pipeline are not in place, it will pose a threat to the safe operation of the pipeline system.

[0003] Specifically, insufficient thermal insulation will cause local heat dissipation of the pipeline to be too fast, resulting in a rapid drop in the temperature of the molten salt. Once the temperature of the molten salt drops below its melting point, solidification is likely to occur, and then the pipeline will be blocked. This situation will not only affect the normal operation of the absorber, but may also lead to serious safety accidents such as pipe explosion, thus bringing high maintenance costs and serious economic losses.

[0004] In addition, when choosing the tube screen of the absorber, if the upper fixing method is adopted, the tube screen will expand downward after being heated. Since the salt drainage pipeline and the thermal insulation layer will also expand downward with the tube screen, the original pipeline will be in direct contact with the external air. In this way, the heat transferred in the pipeline will radiate outward, causing unnecessary heat loss. This heat loss will not only reduce the efficiency of the system, but may also exacerbate the solidification and blockage problems of the molten salt.

[0005] Therefore, in order to ensure the stable operation and safety of the tower-type solar thermal power generation system, effective thermal insulation measures must be taken to reduce the heat dissipation and heat loss of the pipeline. At the same time, the thermal insulation structure also needs to be reasonably designed to avoid the problem that the salt drainage pipeline is in direct contact with the external air due to expansion. Summary of the Invention

[0006] (1) Technical Problems to be Solved

[0007] The present invention provides a thermal insulation structure and method for an absorber, aiming to solve the problems of large local heat dissipation, easy solidification of molten salt, and even freezing blockage and pipe explosion caused by the direct contact of the salt drainage pipeline with the external air after thermal expansion during the operation of the absorber.

[0008] (2) Technical Solutions

[0009] To achieve the above object, the present invention provides a heat-insulating structure for a heat absorber. The heat-insulating structure is disposed below a heat-insulating box body and covers a pipeline located at the bottom of the heat-insulating box body. Along the radial direction of the pipeline, the heat-insulating structure sequentially includes a first heat-insulating layer, a sleeve, and a second heat-insulating layer from inside to outside. The first heat-insulating layer includes a heat-insulating layer main body and a heat-insulating ring. A circular step is provided at the top of the heat-insulating layer main body. The heat-insulating ring capable of moving up and down is provided on the circular step and is connected to the heat-insulating ring through a first elastic member.

[0010] Both the sleeve and the second heat-insulating layer are fixed to the bottom of the heat-insulating box body. After the pipeline expands due to heat, it drives the heat-insulating layer main body to move downward along the inner wall of the sleeve. The heat-insulating ring moves upward along the inner wall of the sleeve under the drive of the first elastic member until the gap between the heat-insulating layer main body and the bottom of the heat-insulating box body is blocked. The second heat-insulating layer has second elastic members circumferentially distributed around the heat-insulating layer main body at a position below the sleeve. A sealing ring is provided between the second elastic members and the heat-insulating layer main body.

[0011] A further technical solution lies in that the second heat-insulating layer includes a heat-insulating box and heat-insulating cotton. The upper part of the heat-insulating box and the sleeve form a first chamber. The lower part of the heat-insulating box and the heat-insulating layer main body form a second chamber. The first chamber is filled with the heat-insulating cotton. The sealing ring and a plurality of the second elastic members are sequentially arranged from inside to outside in the second chamber.

[0012] A further technical solution lies in that a plurality of partition plates are provided in the second chamber. The plurality of partition plates are annularly arranged along the radial direction of the heat-insulating box and divide the second chamber into a plurality of third chambers. One of the second elastic members is provided in each of the third chambers.

[0013] A further technical solution is that the cross-section of the sealing ring is "U"-shaped, and the sealing ring rolls flexibly with the movement of the insulation layer body. The sealing ring includes a first sealing edge pressed against the insulation layer body, a second sealing edge connected to the second elastic member, and an arc-shaped sealing edge integrally connected to the first sealing edge and the second sealing edge. When the sealing ring rolls flexibly, the arc-shaped sealing edge is positioned accordingly to change the width of the first sealing edge and the second sealing edge. The first sealing edge is close to an end face of the insulation layer body and is provided with a plurality of convex rings. The outer surface of the insulation layer body is provided with a plurality of annular grooves for inserting the convex rings. The end face of the first sealing edge away from the insulation layer body is provided with retaining hard sheets evenly spaced in the circumferential direction on a side away from the arc-shaped sealing edge. The end face of the insulation box away from the insulation box body is coaxially provided with a ring-shaped cover plate that covers the second chamber. An annular gap is formed between the inner periphery of the cover plate and the insulation layer body for the first sealing edge and the retaining hard sheet to extend out.

[0014] A further technical solution is that the thermal insulation cotton is selected from any one of aluminum silicate, aerogel, and ceramic fiber.

[0015] A further technical solution is that a first flange is provided at the top outer edge of the insulation box, the first flange is fixedly connected to the bottom of the insulation box body by screws, and a through hole capable of passing the pipe and the insulation layer body is provided at the bottom center of the insulation box.

[0016] A further technical solution is that a second flange is provided at the top edge of the sleeve, and the second flange is fixedly connected to the bottom of the thermal insulation box body by screws.

[0017] A further technical solution is that a thermal insulation skin is provided on the outer side of the thermal insulation layer body, the inner surface of the sleeve is polished, and the sleeve and the thermal insulation skin can be relatively slidably arranged.

[0018] A further technical solution is that the outer side of the thermal insulation ring is wrapped with the thermal insulation skin and can be relatively slidably arranged with the sleeve.

[0019] The heat preservation method equipped with the heat preservation structure comprises the following steps:

[0020] S1: Installing the heat-insulating structure for the heat absorber at the bottom of the heat-insulating box;

[0021] S2: The pipeline connected to the lower header starts to move downward due to the thermal expansion of the tube panel, and drives the main body of the insulation layer to move downward synchronously;

[0022] S3: The thermal insulation ring moves upward under the elastic force of the first elastic member and blocks the gap formed between the thermal insulation box body and the downward-moving main body of the thermal insulation layer; the sealing ring, under the action of the second elastic member, clings to the outer side of the downward-moving main body of the thermal insulation layer.

[0023] S4: After the pipeline cools down, the main body of the thermal insulation layer retracts upward synchronously with the pipeline, and the first elastic member between the thermal insulation ring and the main body of the thermal insulation layer is compressed.

[0024] (III) Beneficial effects

[0025] In the thermal insulation structure provided by the present invention, the sleeve and the second thermal insulation layer are fixedly installed below the thermal insulation box body and will not move downward as the pipeline expands and moves downward due to heat. During the operation of the heat absorber, the pipeline expands and moves downward due to heat. At this time, since the coefficient of thermal expansion of the main body of the thermal insulation layer is different from that of the pipeline, a gap is formed at the connection between the thermal insulation box body and the pipeline, and a part of the pipeline at the gap is exposed outside the main body of the thermal insulation layer. At this time, the thermal insulation ring begins to move upward under the elastic force of the first elastic member and blocks the gap formed between the thermal insulation box body and the downward-moving main body of the thermal insulation layer; at the same time, the sealing ring, under the action of the second elastic member, clings to the outer side of the downward-moving main body of the thermal insulation layer, effectively preventing external cold air from entering the above gap along the gap between the sleeve and the main body of the thermal insulation layer, resulting in heat loss. The double protection of the thermal insulation ring and the sealing ring can effectively solve the problem that during the operation of the heat absorber, some pipelines of the desalting pipeline connected to the lower header are not thermally insulated due to the downward movement of the pipe screen caused by heat expansion, ensuring that the pipeline can reach the set temperature during the operation of the heat absorber and preventing phenomena such as freezing and bursting of the molten salt in the pipeline. Description of the drawings

[0026] Figure 1 It is a schematic diagram of the overall installation structure of the thermal insulation structure for the heat absorber;

[0027] Figure 2 is Figure 1 the enlarged view of part A in

[0028] Figure 3 It is a partial explosion schematic diagram of the thermal insulation structure for the heat absorber.

[0029]

Description of the reference numerals

[0030] 1. Heat preservation box body; 2. Pipeline; 3. First heat preservation layer; 31. Heat preservation layer main body; 311. Annular step; 312. Heat preservation skin; 313. Ring groove; 32. Heat preservation ring; 4. Sleeve; 41. Second flanging; 5. Second heat preservation layer; 51. Heat preservation box; 511. First chamber; 512. Second chamber; 513. Third chamber; 514. First flanging; 515. Cover plate; 516. Annular gap; 52. Heat preservation cotton; 6. First elastic member; 7. Second elastic member; 8. Sealing ring; 81. First sealing edge; 811. Convex ring; 82. Second sealing edge; 83. Arc-shaped sealing edge; 84. Holding hard piece; 9. Partition board; 10. Screw; 11. Lower header. Detailed implementation manners

[0031] For better explaining the present invention for easy understanding, the present invention will be described in detail below in conjunction with the accompanying drawings through specific implementation manners.

[0032] This embodiment provides a heat preservation structure for a heat absorber, as Figure 1 and Figure 2 shown. The heat preservation structure is arranged below the heat preservation box body 1 and covers the pipeline 2 at the bottom of the heat preservation box body 1. Along the radial direction of the pipeline 2, the heat preservation structure sequentially includes a first heat preservation layer 3, a sleeve 4, and a second heat preservation layer 5 from inside to outside. The first heat preservation layer 3 includes a heat preservation layer main body 31 and a heat preservation ring 32. An annular step 311 is arranged at the top of the heat preservation layer main body 31, and the heat preservation ring 32 is arranged on the annular step 311 and is connected to the heat preservation ring 32 through a first elastic member 6. The first elastic member 6 in this embodiment is preferably a spring. When the pipeline 2 is not heated, the spring is in a compressed state, and the heat preservation ring 32 is kept in contact with the bottom of 1 under the action of 6. Both the sleeve 4 and the second heat preservation layer 5 are fixed to the bottom of the heat preservation box body 1. When the pipeline 2 expands due to heat and drives the heat preservation layer main body 31 to move downward along the inner wall of the sleeve 4, the heat preservation ring 32 continuously abuts under the action of the first elastic member 6 to ensure that there is no gap between the heat preservation layer main body 31 and the bottom of the heat preservation box body 1. The second heat preservation layer 5 has a second elastic member 7 (the second elastic member 7 in this embodiment is selected as a spring) distributed circumferentially around the heat preservation layer main body 31 at a position below the sleeve 4, and a sealing ring 8 is arranged between the second elastic member 7 and the heat preservation layer main body 31.

[0033] It should be noted here that the lower header 11 is placed inside the heat preservation box body 1, the upper end of the pipeline 2 is connected to the lower header 11 inside the heat preservation box body 1, and the inside of the lower header 11 is high-temperature molten binary molten salt. The main function of the heat preservation box body 1 is to provide heat preservation for the molten salt in the lower header 11. The pipeline 2 can slide up and down relative to the connection part of the heat preservation box body 1. This is mainly to provide displacement conditions for the thermal expansion of the pipeline 2 and prevent the expanded pipeline 2 from damaging the heat preservation box body 1.

[0034] The above technical solution has the following technical effects: The sleeve 4 and the second thermal insulation layer 5 in the thermal insulation structure are fixedly installed below the thermal insulation box body 1 and will not move downward as the pipeline 2 expands and moves downward due to heat. During the operation of the heat absorber, the pipeline 2 expands due to heat and moves downward. At this time, since the coefficient of thermal expansion of the main body 31 of the thermal insulation layer is different from that of the pipeline 2, a gap is formed at the connection between the thermal insulation box body 1 and the pipeline 2, and a part of the pipeline 2 at the gap is exposed outside the main body 31 of the thermal insulation layer. At this time, the thermal insulation ring 32 starts to move upward under the elastic force of the first elastic member 6 and blocks the gap formed between the thermal insulation box body 1 and the downward-moving main body 31 of the thermal insulation layer; at the same time, under the action of the second elastic member 7, the sealing ring 8 is closely attached to the outer side of the downward-moving main body 31 of the thermal insulation layer, effectively preventing external cold air from entering the above-mentioned gap along the gap between the sleeve 4 and the main body 31 of the thermal insulation layer, resulting in heat loss. The double protection of the thermal insulation ring 32 and the sealing ring 8 can effectively solve the problem that during the operation of the heat absorber, part of the pipeline 2 of the desalting pipeline 2 connected to the lower header 11 is not thermally insulated due to the downward movement of the pipe screen caused by heat expansion, ensuring that the pipeline 2 can reach the set temperature during the operation of the heat absorber and preventing phenomena such as freezing and bursting of the molten salt in the pipeline 2.

[0035] In this embodiment, the second thermal insulation layer 5 includes a thermal insulation box 51 and thermal insulation cotton 52. Specifically, a first chamber 511 is formed between the upper part of the thermal insulation box 51 and the sleeve 4, and a second chamber 512 is formed between the lower part of the thermal insulation box 51 and the main body 31 of the thermal insulation layer. The first chamber 511 is filled with thermal insulation cotton 52, and a sealing ring 8 and a plurality of second elastic members 7 are sequentially arranged from the inside to the outside in the second chamber 512. There are 12 second elastic members 7 in this embodiment. The number of the second elastic members 7 should be as large as possible so as to ensure that the elastic force received by each part of the sealing ring 8 is uniform. The sealing ring 8 is selected as a lip seal, and a push plate can be added between the sealing ring 8 and the second elastic member 7. The above design can effectively prevent air from entering the thermal insulation box 51 and affecting the overall thermal insulation effect of the pipeline 2 and the lower header 11.

[0036] See Figure 2 and Figure 3 , in this embodiment, a plurality of partition plates 9 are arranged in the second chamber 512. The number of the partition plates 9 should be based on the number of the second elastic members 7. In this embodiment, there are 12 partition plates 9. The 12 partition plates 9 are arranged in a radial ring along the thermal insulation box 51 and divide the second chamber 512 into a plurality of third chambers 513, and one second elastic member 7 is arranged in each third chamber 513. Since the second elastic members 7 in this embodiment are springs, the main function of the partition plates 9 here is to restrict the deformation direction of the second elastic members 7 and prevent them from intersecting with each other. It should be noted here that the main body of the structure of the thermal insulation box 51 is made by sheet metal processing. Specifically, the thermal insulation box 51 is circular in this embodiment, and of course, it can also be square.

[0037] The cross-section of the sealing ring 8 is in a "U" shape. The sealing ring 8 rolls flexibly with the movement of the main body 31 of the thermal insulation layer. The sealing ring 8 includes a first sealing edge 81 that abuts against the main body 31 of the thermal insulation layer, a second sealing edge 82 connected to the second elastic member 7, and an arc-shaped sealing edge 83 integrally and arc-shapedly connecting the first sealing edge 81 and the second sealing edge 82. When the sealing ring 8 rolls flexibly, the arc-shaped sealing edge 83 follows the position to change the widths of the first sealing edge 81 and the second sealing edge 82. A plurality of circles of convex rings 811 are arranged on one end face of the first sealing edge 81 close to the main body 31 of the thermal insulation layer. A plurality of circles of annular grooves 313 for inserting the convex rings 811 are provided on the outer surface of the main body 31 of the thermal insulation layer. On one end face of the first sealing edge 81 far from the main body 31 of the thermal insulation layer, holding hard sheets 84 are circumferentially and evenly spaced on the side far from the arc-shaped sealing edge 83. On one end face of the heat preservation box 51 far from the heat preservation box body 1, a cover plate 515 in a ring shape and covering the second chamber 512 is coaxially provided. An annular gap 516 for the first sealing edge 81 and the holding hard sheets 84 to extend out is formed between the inner circumference of the cover plate 515 and the main body 31 of the thermal insulation layer.

[0038] Further, the thermal insulation cotton 52 is selected from any one of aluminum silicate, aerogel, and ceramic fiber. In this embodiment, it is selected as ceramic fiber, but it is not limited to the types mentioned above, and all materials with thermal insulation functions can be selected.

[0039] Specifically, in this embodiment, a first flanging 514 is provided at the outer edge of the top of the heat preservation box 51. The first flanging 514 and the bottom of the heat preservation box body 1 are fixedly connected by screws 10. This fixing method is convenient and efficient for installation. A through hole capable of passing through the pipeline 2 and the main body 31 of the thermal insulation layer is provided at the center of the bottom of the heat preservation box 51.

[0040] Specifically, in this embodiment, a second flanging 41 is provided at the top edge of the sleeve 4. The second flanging 41 and the bottom of the heat preservation box body 1 are fixedly connected by screws 10. Using screw connection is convenient and efficient for installation.

[0041] Specifically, in this embodiment, a thermal insulation skin 312 is provided on the outer side of the main body 31 of the thermal insulation layer. The inner surface of the sleeve 4 is polished. The sleeve 4 and the thermal insulation skin 312 can be slidably arranged relative to each other. The outer side of the thermal insulation ring 32 is wrapped with the thermal insulation skin 312 and can be slidably arranged relative to the sleeve 4. This can reduce the friction between the sleeve 4 and the main body 31 of the thermal insulation layer and the thermal insulation ring 32, prevent the thermal insulation material inside the first thermal insulation layer 3 from directly rubbing against the inner wall of the sleeve 4, provide a protection effect on the first thermal insulation layer 3, and improve the service life of the first thermal insulation layer 3. Moreover, it can also play a better guiding role.

[0042] A thermal insulation method using the above-mentioned thermal insulation structure for the heat absorber is as follows:

[0043] S1: Install the heat absorber thermal insulation structure as described above at the bottom of the thermal insulation box body 1;

[0044] S2: The pipe 2 connected to the lower header 11 starts to move downward due to the thermal expansion of the tube screen, and drives the main body 31 of the thermal insulation layer to move downward synchronously;

[0045] S3: The thermal insulation ring 32 moves upward under the elastic force of the first elastic member 6 and blocks the gap formed between the thermal insulation box body 1 and the downward-moving main body 31 of the thermal insulation layer; the sealing ring 8, under the action of the second elastic member 7, clings to the outer side of the downward-moving main body 31 of the thermal insulation layer;

[0046] S4: After the pipe 2 cools down, the main body 31 of the thermal insulation layer retracts upward synchronously with the pipe 2, and the first elastic member 6 between the thermal insulation ring 32 and the main body 31 of the thermal insulation layer is compressed.

[0047] During the implementation of the above solution, the thickness of the thermal insulation ring 32 should be greater than the maximum downward movement distance of the pipe 2 to ensure that the thermal insulation ring 32 will not slip off, and when cooling later, the pipe 2 and the main body 31 of the thermal insulation layer can retract smoothly.

[0048] It should be noted that all directional indicators (such as up, down, left, right, front, back...) in this embodiment are only used to explain the relative positional relationship and movement conditions between components in a certain specific posture (as shown in the attached drawings). If this specific posture changes, then the directional indicators will change accordingly.

[0049] In addition, in this embodiment, descriptions such as "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of this embodiment, "a plurality" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0050] In this embodiment, unless otherwise clearly specified and limited, terms such as "connection" and "fixation" should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and can be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0051] It should be understood that the above description of the specific embodiments of the present invention is only for explaining the technical route and features of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. However, the present invention is not limited to the above specific embodiments. Any changes or modifications made within the scope of the claims of the present invention should be covered by the protection scope of the present invention.

Claims

1. A heat absorber insulation structure, characterized in that, The heat insulation structure is arranged below the heat insulation box body (1) and wraps the pipeline (2) at the bottom of the heat insulation box body (1). Along the radial direction of the pipeline (2), the heat insulation structure sequentially includes a first heat insulation layer (3), a sleeve (4) and a second heat insulation layer (5) from inside to outside; The first heat insulation layer (3) includes a heat insulation layer main body (31) and a heat insulation ring (32). A circular step (311) is arranged at the top of the heat insulation layer main body (31). The heat insulation ring (32) capable of moving up and down is arranged on the circular step (311) and is connected with the heat insulation ring (32) through a first elastic member (6); Both the sleeve (4) and the second heat insulation layer (5) are fixed to the bottom of the heat insulation box body (1). After the pipeline (2) expands due to heat, it drives the heat insulation layer main body (31) to move downward along the inner wall of the sleeve (4). The heat insulation ring (32) moves upward along the inner wall of the sleeve (4) under the drive of the first elastic member (6) until the gap between the heat insulation layer main body (31) and the bottom of the heat insulation box body (1) is blocked; The second heat insulation layer (5) has second elastic members (7) distributed circumferentially around the heat insulation layer main body (31) at a position below the sleeve (4). A sealing ring (8) is arranged between the second elastic members (7) and the heat insulation layer main body (31).

2. The heat-insulating structure for a heat absorber according to claim 1, wherein, The second heat insulation layer (5) includes a heat insulation box (51) and heat insulation cotton (52); The upper part of the heat insulation box (51) and the sleeve (4) form a first chamber (511). A second chamber (512) is formed between the lower part of the heat insulation box (51) and the heat insulation layer main body (31). The first chamber (511) is filled with the heat insulation cotton (52). The sealing ring (8) and a plurality of the second elastic members (7) are sequentially arranged inside the second chamber (512) from inside to outside.

3. The heat-insulating structure for the heat absorber according to claim 2, wherein, A plurality of partition plates (9) are arranged in the second chamber (512). The plurality of partition plates (9) are arranged in a circular ring along the radial direction of the heat insulation box (51) and divide the second chamber (512) into a plurality of third chambers (513). One of the second elastic members (7) is arranged in each of the third chambers (513).

4. The heat-insulating structure for a heat absorber according to claim 2, characterized in that, The cross-section of the sealing ring (8) is in a "U" shape. The sealing ring (8) performs flexible rolling as the thermal insulation layer main body (31) moves. The sealing ring (8) includes a first sealing edge (81) that abuts against the thermal insulation layer main body (31), a second sealing edge (82) connected to the second elastic member (7), and an arc-shaped sealing edge (83) integrally and arc-shapedly connected to the first sealing edge (81) and the second sealing edge (82). When the sealing ring (8) performs flexible rolling, the arc-shaped sealing edge (83) follows the position to change the widths of the first sealing edge (81) and the second sealing edge (82). Multiple rings of convex rings (811) are arranged on one end face of the first sealing edge (81) close to the thermal insulation layer main body (31). Multiple rings of annular grooves (313) for inserting the convex rings (811) are formed on the outer surface of the thermal insulation layer main body (31). Keeping hard sheets (84) are circumferentially and evenly spaced on one end face of the first sealing edge (81) far from the thermal insulation layer main body (31) and on the side far from the arc-shaped sealing edge (83). A cover plate (515) that is annular and covers the second chamber (512) is coaxially arranged on one end face of the heat preservation box (51) far from the heat preservation box body (1). An annular gap (516) for the first sealing edge (81) and the keeping hard sheets (84) to extend out is formed between the inner circumference of the cover plate (515) and the thermal insulation layer main body (31).

5. The heat-insulating structure for a heat absorber according to claim 2, characterized in that, The thermal insulation cotton (52) is selected from any one of aluminum silicate, aerogel, and ceramic fiber.

6. The heat-insulating structure for a heat absorber according to claim 2, wherein A first flanging (514) is arranged at the outer edge of the top of the heat preservation box (51). The first flanging (514) and the bottom of the heat preservation box body (1) are fixedly connected by screws (10). A through hole capable of passing through the pipeline (2) and the thermal insulation layer main body (31) is arranged at the center of the bottom of the heat preservation box (51).

7. The heat-insulating structure for a heat absorber according to claim 1, characterized in that, A second flanging (41) is provided at the top edge of the sleeve (4). The second flanging (41) and the bottom of the heat preservation box body (1) are fixedly connected by screws (10).

8. The heat-insulating structure for a heat absorber according to claim 1, wherein, A heat preservation skin (312) is arranged on the outer side of the thermal insulation layer main body (31). The inner surface of the sleeve (4) is polished. The sleeve (4) and the heat preservation skin (312) are slidably arranged relative to each other.

9. The heat-insulating structure for a heat absorber according to claim 8, characterized in that, The outer side of the heat preservation ring (32) is wrapped with the heat preservation skin (312) and is slidably arranged relative to the sleeve (4).

10. A method for insulating a heat absorber, characterized in that, The specific heat preservation process is as follows: S1: Install the heat absorber heat preservation structure according to any one of claims 1-9 at the bottom of the heat preservation box body (1); S2: The pipeline (2) connected to the lower header (11) starts to move downward due to the thermal expansion of the tube screen, and drives the thermal insulation layer main body (31) to move downward synchronously; S3: The heat preservation ring (32) moves upward under the elastic force of the first elastic member (6) and blocks the gap formed between the heat preservation box body (1) and the downward-moving heat preservation layer main body (31); the sealing ring (8) is pressed against the outer side of the downward-moving heat preservation layer main body (31) under the action of the second elastic member (7). S4: After the pipeline (2) cools down, the heat preservation layer main body (31) retracts upward synchronously with the pipeline (2), and the first elastic member (6) between the heat preservation ring (32) and the heat preservation layer main body (31) is compressed.

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