A linear Fresnel type high-temperature and high-pressure heat collecting tube

Abstract

The present invention discloses a linear Fresnel type high-temperature and high-pressure heat collection tube, belonging to the field of solar thermal power generation technology. It includes an inner tube and an outer tube. Both ends of the inner tube and the outer tube are fixedly connected through flanges. One side of the inner tube is fixedly connected with an inner tube special-shaped cavity. Inner tube expansion joints are arranged at both ends of the inner tube. A special-shaped cavity shrinkage opening is arranged on the inner tube. An outer tube expansion joint is arranged on the outer tube. A heat dissipation plate is fixedly connected to the lower part of the inner tube special-shaped cavity. Heat dissipation fins are fixedly connected to the heat dissipation plate. A long strip-shaped installation opening is axially formed in the lower part of the outer tube for installing a glass sheet. The temperature change of the outer tube is very small, so the axial expansion amount of the outer tube is very small, and the relative displacement between the outer tube and the glass sheet will be very small. This solves the defect problems caused by the defects of the sealing ring between the glass tube and the stainless steel tube and the different axial expansion amounts of the glass tube and the stainless steel tube in the existing glass vacuum heat collection tube, enabling the heat collection tube of the present invention to work under higher temperature and higher pressure conditions.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar thermal power generation, and particularly relates to a linear Fresnel type high-temperature and high-pressure heat collecting tube. Background Art

[0002] The existing linear Fresnel molten salt type high-temperature heat collecting tube uses a stainless steel inner tube with a glass tube jacket, and the space between the two tubes is sealed at both ends with a high-temperature resistant material and then evacuated. Due to reasons such as the heat resistance and strength of the sealing material, and the difference in radial and axial expansion coefficients between the stainless steel material and the glass material, the working temperature of the existing high-temperature heat collecting tube is only about 600 °C, and the working pressure is only about 5-6 MP, which greatly limits the power per meter of the heat collecting tube. When the research and development of molten salt or other working media make progress and their working temperature exceeds the highest working temperature of the heat collecting tube, the existing heat collecting tubes will not be able to meet the requirements of higher temperature and higher pressure. It is reported that the Molten Salt Chemistry and Engineering Technology Department of the Shanghai Institute of Applied Physics, Chinese Academy of Sciences has made a breakthrough in the research and development of molten salt, making the working temperature of the molten salt exceed 800 °C. According to the existing molten salt working temperature of 600 °C and releasing heat to 300 °C, the heat release temperature that can be used is 300 °C. While the molten salt with a working temperature of 800 °C releases heat to 300 °C, the heat release temperature that can be used is 500 °C, increasing the heat storage utilization rate by 66.7%. The molten salt heat exchanger at 800 °C will generate steam close to 800 °C, thereby improving the thermal efficiency of the steam turbine and further improving the efficiency of the solar thermal power generation system. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to solve the defect problems caused by the defects of the sealing ring between the glass tube and the stainless steel tube and the different axial expansion amounts of the glass tube and the stainless steel tube in the existing glass vacuum heat collecting tube.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A linear Fresnel type high-temperature and high-pressure heat collecting tube, comprising an inner tube and an outer tube. Both ends of the inner tube and the outer tube are fixedly connected by flanges. One side of the inner tube is fixedly connected with an inner tube special-shaped cavity. Inner tube expansion joints are provided at both ends of the inner tube. A special-shaped cavity shrinkage port is provided on the inner tube. An outer tube expansion joint is provided on the outer tube. A heat dissipation plate is fixedly connected to the lower part of the inner tube special-shaped cavity, and heat dissipation fins are fixedly connected to the heat dissipation plate.

[0006] A clamping groove is provided on the outer tube, and the enclosure is completed through a glass sheet, a filling seal, a filling seal installation groove and the clamping groove. The space between the inner tube and the outer tube is enclosed and evacuated, and a rectangular opening is provided on one side of the inner tube.

[0007] The heat dissipation plate extends into the interior of the inner tube, and the inner tube special-shaped cavity is communicated with the inner tube through the heat dissipation plate.

[0008] The number of the flanges is two. An inner sealing ring is fixedly connected to the outer side of one flange, and an outer sealing ring is fixedly connected to the outer side of the other flange.

[0009] The inner sealing ring is concave, and the outer sealing ring is convex.

[0010] Anti-reflection layers are coated on the outer sides of the inner pipe and the inner pipe special-shaped cavity, and a reflection layer is coated on the inner wall of the outer pipe.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] Since the glass vacuum tube structure is abandoned and the annular sealing ring of the glass tube and the stainless steel tube is no longer used, only a long strip-shaped installation opening is axially formed at the lower part of the outer pipe for installing the glass sheet, and the temperature change of the outer pipe is very small. Therefore, the axial expansion amount of the outer pipe is very small, and the relative displacement between the outer pipe and the glass sheet will be very small, which can be completely solved by the existing sealing materials. This solves the defect problems of the existing glass vacuum heat collecting tube caused by the defects of the sealing ring between the glass tube and the stainless steel tube and the different axial expansion amounts of the glass tube and the stainless steel tube, enabling the heat collecting tube of the present invention to work under higher temperature and higher pressure conditions.

[0013] Sunlight is reflected by the primary mirror and focused by the linear Fresnel lens, and the focal line passes through the glass sheet. The outer side of the glass sheet is arc-shaped and the inner side is flat, thick in the middle and thin on both sides, which is equivalent to a focusing mirror. The light is focused again and then irradiated to the bottom of the inner pipe special-shaped cavity. After the bottom of the inner pipe special-shaped cavity absorbs heat, part of the heat is transferred to the molten salt flowing in the inner pipe special-shaped cavity, and the other part of the heat is transferred to the molten salt flowing in the inner pipe special-shaped cavity and the inner pipe through the heat dissipation plate and the heat dissipation fins. Due to the use of the heat dissipation plate and the heat dissipation fins, the heat absorbed by the bottom of the inner pipe special-shaped cavity will be transferred to the molten salt at a faster speed, improving the efficiency of the heat collecting tube.

[0014] Part of the scattered heat is irradiated to the outer wall of the inner pipe, the outer wall of the inner pipe special-shaped cavity and the inner wall of the outer pipe. Because anti-reflection coatings are coated on the outer walls of the inner pipe and the inner pipe special-shaped cavity, part of the heat irradiated to their outer walls will be absorbed. A reflection layer is coated on the inner wall of the outer pipe, so part of the heat irradiated to the inner wall of the outer pipe will be reflected, and part of the reflected heat is reflected to the outer walls of the inner pipe and the inner pipe special-shaped cavity and absorbed. Therefore, the utilization rate of the thermal energy entering between the inner and outer pipes is improved, and the efficiency of the heat collecting tube is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of an embodiment of the present invention.

[0016] Figure 2 is a schematic structural diagram of a rectangular opening of an embodiment of the present invention.

[0017] Figure 3 is a schematic structural diagram of a filling seal of an embodiment of the present invention.

[0018] Figure 4 It is a schematic side view of an embodiment of the present invention.

[0019] Figure 5 It is an embodiment of the present invention Figure 4 The enlarged schematic view of part A.

[0020] Figure 6 It is an embodiment of the present invention Figure 5 The enlarged schematic view of part B.

[0021] Reference numerals and names of the drawings: inner tube 1, outer tube 2, special-shaped cavity of inner tube 3, glass sheet 4, heat dissipation plate 5, heat dissipation fin 6, flange 7, flange hole 8, inner sealing ring 9, outer sealing ring 10, clamping groove 11, inner tube expansion joint 12, outer tube expansion joint 13, rectangular opening 14, contraction opening of special-shaped cavity 15, filling seal 16, filling seal installation groove 17. Detailed implementation manners

[0022] The present invention will be described in detail below in conjunction with the drawings and specific embodiments. Here, the schematic embodiments and descriptions of the present invention are used to explain the present invention, but not to limit the present invention.

[0023] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0024] Embodiment 1

[0025] Such as Figures 1-4As shown in the figure, a linear Fresnel type high-temperature and high-pressure heat collecting tube according to the present invention includes an inner tube 1 and an outer tube 2. Both ends of the inner tube 1 and the outer tube 2 are fixedly connected through flanges 7. An inner tube special-shaped cavity 3 is fixedly connected to one side of the inner tube 1. Inner tube expansion joints 12 are provided at both ends of the inner tube 1. A special-shaped cavity shrinkage opening 15 is provided on the inner tube 1. An outer tube expansion joint 13 is provided on the outer tube 2. A heat dissipation plate 5 is fixedly connected to the lower part of the inner tube special-shaped cavity 3. Heat dissipation fins 6 are fixedly connected to the heat dissipation plate 5. A card slot 11 is provided on the outer tube 2. Sealing is completed through a glass sheet 4, a filling seal 16, a filling seal installation groove 17 and the card slot 11. The space between the inner tube 1 and the outer tube 2 is sealed and evacuated. A rectangular opening 14 is provided on one side of the inner tube 1. The heat dissipation plate 5 extends into the inner tube 1. The inner tube special-shaped cavity 3 is connected to the inner tube 1 through the heat dissipation plate 5. The number of the flanges 7 is two. An inner sealing ring 9 is fixedly connected to the outside of one flange 7. An outer sealing ring 10 is fixedly connected to the outside of the other flange 7. The inner sealing ring 9 is concave-shaped. The outer sealing ring 10 is convex-shaped. Anti-reflection layers are coated on the outer sides of the inner tube 1 and the inner tube special-shaped cavity 3. A reflection layer is coated on the inner wall of the outer tube 2.

[0026] Anti-reflection layers are coated on the outer walls of the inner tube 1 and the inner tube special-shaped cavity 3, and a reflection layer is coated on the inner wall of the outer tube 2. The inner tube 1 and the outer tube 2 are of the same length and are fixedly connected through flanges 7 at both ends. The glass sheet 4 is snapped into the card slot 11, and a sealing material is inlaid between the glass sheet 4 and the card slot 11. A sealed space is formed between the inner tube 1 and the outer tube 2 and evacuated. The upper left and right sides of the inner tube special-shaped cavity 3 are fixedly connected to the lower tube wall of the inner tube 1. The lower part of the inner tube special-shaped cavity 3 is fixedly connected to the heat dissipation plate 5. The heat dissipation plate 5 is fixedly connected to the heat dissipation fins 6. A plurality of rectangular openings 14 are spacedly provided on the lower tube wall of the inner tube 1, so that the heat dissipation plate 5 is inserted into the inner tube 1 and the inner tube 1 is communicated with the inner tube special-shaped cavity 3. When the inner tube special-shaped cavity 3 approaches the flanges 7 at both ends, it inclines and contracts towards the inner tube 1 until it has the same diameter as the inner tube 1, and the special-shaped cavity shrinkage opening 15 is communicated with the inner tube 1. Inner tube expansion joints 12 are arranged on the inner sides of the flanges 7 when both ends of the inner tube 1 approach the flanges 7. Outer tube expansion joints 13 are arranged on the inner sides of the flanges 7 when both ends of the outer tube 2 approach the flanges 7. Inner sealing rings 9 and outer sealing rings 10 are arranged on the outer sides of the flanges 7 at both ends of the pipeline. The inner sealing ring 9 on one side protrudes and the outer sealing ring 10 is concave, and the inner sealing ring 9 on the other side is concave and the outer sealing ring 10 protrudes. When connecting the pipelines, sealant is filled into the concave sealing ring, the card slots 11 are aligned, and then bolts are passed through the flange holes 8 to tighten the two flanges 7, so that the protruding sealing ring is embedded into the concave sealing ring and the sealant is pressed tightly.

[0027] Because the glass vacuum tube structure is abandoned and the annular sealing ring between the glass tube and the stainless steel tube is no longer used, only a long strip installation opening is provided axially along the lower portion of the outer tube 2 for mounting the glass sheet 4. The temperature fluctuation of the outer tube 2 is minimal, and therefore the axial expansion of the outer tube 2 is very small, and the relative displacement between the outer tube 2 and the glass sheet 4 is very small, which can be completely solved by existing sealing materials. This solves the problems of existing glass vacuum tubes caused by defects in the sealing ring between the glass tube and the stainless steel tube and the different axial expansion of the glass tube and the stainless steel tube, enabling the heat collection tube of the present invention to operate under higher temperature and higher pressure conditions.

[0028] After sunlight is reflected by a primary reflector and focused by a linear Fresnel lens, its focal line passes through glass sheet 4. Glass sheet 4 is curved on the outside and flat on the inside, with a thick center and thin sides, acting as a focusing lens. This refocuses the light and directs it to the bottom of the inner tube's shaped cavity 3. The bottom absorbs heat, transferring some of it to the molten salt flowing within it. The remaining heat is transferred to the molten salt flowing within the inner tube's shaped cavity 3 and inner tube 1 via heat sink 5 and fins 6. The use of heat sink 5 and fins 6 allows the heat absorbed by the bottom of the inner tube's shaped cavity 3 to be transferred to the molten salt more quickly, improving the efficiency of the solar collector. Some of the scattered heat reaches the outer walls of inner tube 1, inner tube's shaped cavity 3, and outer tube 2. Because the outer walls of inner tube 1 and inner tube's shaped cavity 3 are coated with an anti-reflection coating, some of the heat that reaches these outer walls is absorbed. The inner wall of the outer tube 2 is coated with a reflective layer so part of the heat that hits the inner wall of the outer tube 2 will be reflected, and part of the reflected heat is reflected to the outer wall of the inner tube 1 and the inner tube special-shaped cavity 3 and absorbed. Therefore, the utilization rate of the heat energy entering between the inner and outer tubes is improved, thereby improving the efficiency of the heat collecting tube.

[0029] The axial expansion and contraction of the inner tube 1 due to temperature changes are eliminated by the inner tube expansion joint 12 , and the axial expansion and contraction of the outer tube 2 due to temperature changes are eliminated by the outer tube expansion joint 13 .

[0030] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only intended to help understand the principles of the embodiments of the present invention.

Claims

1. A linear Fresnel type high-temperature and high-pressure heat collecting tube, comprising an inner tube (1) and an outer tube (2), characterized in that: Both ends of the inner tube (1) and the outer tube (2) are fixedly connected through flanges (7). An inner tube special-shaped cavity (3) is fixedly connected to one side of the inner tube (1). Inner tube expansion joints (12) are provided at both ends of the inner tube (1). A special-shaped cavity shrinkage opening (15) is provided on the inner tube (1). An outer tube expansion joint (13) is provided on the outer tube (2). A heat dissipation plate (5) is fixedly connected to the lower part of the inner tube special-shaped cavity (3). Heat dissipation fins (6) are fixedly connected to the heat dissipation plate (5); Only a clamping groove (11) is axially opened at the lower part of the outer tube (2) for installing a glass sheet (4). The outer side of the glass sheet (4) is arc-shaped, the inner side is flat, and it is thick in the middle and thin on both sides. Sealing is completed through the glass sheet (4), the filling seal (16), the filling seal installation groove (17) and the clamping groove (11). The space between the inner tube (1) and the outer tube (2) is sealed and evacuated. A rectangular opening (14) is provided on one side of the inner tube (1); The heat dissipation plate (5) extends into the interior of the inner tube (1). The inner tube special-shaped cavity (3) is communicated with the inner tube (1) through the heat dissipation plate (5); The number of the flanges (7) is two. An inner sealing ring (9) is fixedly connected to the outer side of one flange (7), and an outer sealing ring (10) is fixedly connected to the outer side of the other flange (7); The inner sealing ring (9) is concave-shaped, and the outer sealing ring (10) is convex-shaped; Anti-reflection layers are coated on the outer sides of the inner tube (1) and the inner tube special-shaped cavity (3), and a reflection layer is coated on the inner wall of the outer tube (2).

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