Compensation-free low-temperature vacuum straight pipe and preparation method thereof

Abstract

The invention relates to a compensation-free low-temperature vacuum straight pipe and a preparation method thereof.The low-temperature vacuum straight pipe comprises an inner pipe and an outer pipe which are coaxially arranged in a sleeved mode, supporting rings are welded between the left end and the right end of the outer pipe and the inner pipe in a sealed mode, a vacuumizing connector is welded to the outer pipe in a sealed mode, and the inner pipe is made of low-expansion alloy steel 4J36; the outer pipe, the supporting ring and the vacuumizing connector are made of stainless steel, and the device has the advantages of being simple in structure, low in cost, convenient to maintain and high in reliability. The preparation method has the advantages of simple process and convenience in operation.

Description

Technical Field

[0001] The invention relates to a vacuum tube, in particular to a low-temperature vacuum straight tube without compensation, and a preparation method of the vacuum straight tube. Background Art

[0002] In the aerospace field, cryogenic vacuum tubes are an important component of cryogenic filling systems, which together with cryogenic stop valves, cryogenic regulating valves, etc., form cryogenic medium pipelines. The working medium filled or discharged in the cryogenic filling system is liquid hydrogen, liquid oxygen, liquid nitrogen, liquid methane and other cryogenic media. In order to solve the problem of pipeline flexibility (thermal expansion and contraction) caused by the temperature difference between the cryogenic medium and the ambient temperature and the change in ambient temperature, the field usually sets bellows compensators on the inner tubes of cryogenic vacuum equipment such as cryogenic vacuum tubes. Although this method can solve the problem of pipeline flexibility, its structure is relatively complex, the manufacturing difficulty is relatively high, the cost is relatively high, and it will generate a large load on the pipelines at both ends, requiring additional support structures. Summary of the invention

[0003] The purpose of the present invention is to provide a low-temperature vacuum straight tube that does not require compensation and a preparation method thereof. The vacuum straight tube has the advantages of simple structure, low cost, easy maintenance and high reliability; the preparation method has the advantages of simple process and easy operation.

[0004] In order to solve the above-mentioned problems existing in the prior art, the present invention provides a low-temperature vacuum straight tube that does not require compensation, including an inner tube and an outer tube that are coaxially sleeved, support rings are respectively sealed and welded between the left and right ends of the outer tube and the inner tube, and a vacuum joint is sealed and welded on the outer tube, the inner tube is made of low-expansion alloy steel 4J36, and the outer tube, support ring and vacuum joint are made of stainless steel.

[0005] Furthermore, the present invention provides a low-temperature vacuum straight tube that does not require compensation, wherein a vacuum adsorption box is welded on the outer wall of the inner tube, and an adsorbent is provided in the vacuum adsorption box.

[0006] Furthermore, the present invention provides a low-temperature vacuum straight tube that does not require compensation, wherein the vacuum adsorption box is provided with an adsorbent filling port and a matching plug, and the outer tube is provided with a filling operation hole corresponding to the adsorbent filling port and a matching sealing cover.

[0007] Furthermore, the present invention provides a low-temperature vacuum straight tube that does not require compensation, wherein the outer wall of the inner tube is coated with a heat insulating layer made of a heat insulating material.

[0008] Furthermore, the present invention provides a low-temperature vacuum straight tube that does not require compensation, wherein a support member made of a low heat leakage material is fixed to the outer wall of the inner tube.

[0009] Furthermore, the present invention provides a low-temperature vacuum straight tube that does not require compensation, wherein a left connecting ring and a right connecting ring are seal-welded on the outer wall of the outer tube.

[0010] Furthermore, the present invention provides a low-temperature vacuum straight tube that does not require compensation, wherein the support member is sleeved on the inner tube, and retaining rings welded to the inner tube are provided on both sides of the support member.

[0011] Furthermore, the present invention provides a low-temperature vacuum straight tube that does not require compensation, wherein the left connecting ring and the right connecting ring are made of stainless steel.

[0012] Based on the same concept, the present invention also provides a method for preparing the above-mentioned low-temperature vacuum straight tube, comprising the following steps:

[0013] S1. Welding the vacuum adsorption box and two support rings to the inner tube respectively, wherein the vacuum adsorption box is provided with an adsorbent filling port;

[0014] S2. After the inner tube is covered with an insulating layer by using insulating material, the left and right ends of the outer tube are welded to two supporting rings respectively, wherein a filling operation hole is provided on the outer tube;

[0015] S3, respectively weld the vacuum joint, the left connecting ring and the right connecting ring to the outer tube;

[0016] S4, filling the vacuum adsorption box with adsorbent through the filling operation hole and the adsorbent filling port, sealing the adsorbent filling port with a plug after the filling is completed, and sealing and welding the cover to the filling operation hole;

[0017] S5. Perform vacuuming operation through the vacuuming joint, and close the vacuuming joint after the vacuuming is completed.

[0018] Furthermore, the present invention provides a method for preparing a low-temperature vacuum straight tube, wherein in step S1, before welding the two support rings, an operation of installing a support member on the inner tube is performed, comprising the following steps:

[0019] S1-1, sleeve a support member and two retaining rings correspondingly located on both sides of the support member on the inner tube;

[0020] S1-2. Clamp the two retaining rings on the support and weld them to the inner tube respectively.

[0021] Compared with the prior art, the present invention has the following advantages for a low-temperature vacuum straight tube that does not require compensation and its preparation method: the present invention sets a coaxially sleeved inner tube and outer tube, seals and welds support rings between the left and right ends of the outer tube and the inner tube respectively, and seals and welds a vacuum joint on the outer tube, wherein the inner tube is made of low-expansion alloy steel 4J36, and the outer tube, support ring and vacuum joint are made of stainless steel. Thus, a low-temperature vacuum straight tube that does not require compensation is formed. Compared with the existing low-temperature vacuum tube with a bellows compensator, the present invention makes the inner tube made of low-expansion alloy steel 4J36, and utilizes its low expansion coefficient to adapt to the thermal expansion and contraction caused by the temperature difference without setting a bellows compensator, which not only simplifies the structure and reduces the manufacturing difficulty and cost, but also does not generate a large load on the pipelines at both ends, and does not need to set an additional support structure; by making the outer tube, support ring and vacuum joint made of stainless steel, the corrosion resistance is improved and the service life is extended. The preparation method of the low-temperature vacuum straight tube provided by the present invention has the advantages of simple process and convenient operation.

[0022] The following is a further detailed description of a low-temperature vacuum straight tube without compensation and a preparation method thereof of the present invention in conjunction with the specific embodiments shown in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural schematic diagram of a low-temperature vacuum straight tube that does not require compensation according to the present invention;

[0024] Figure 2 It is a partial enlarged view of position A in the figure;

[0025] Figure 3 This is a partial enlarged view of position B in the figure. DETAILED DESCRIPTION

[0026] First of all, it should be explained that the directional words such as up, down, left, right, front and back described in the present invention are only described according to the drawings for the convenience of understanding, and are not intended to limit the technical solution and the scope of protection of the present invention.

[0027] like Figures 1 to 3The specific implementation of a low-temperature vacuum straight tube without compensation of the present invention is shown, comprising an inner tube 1 and an outer tube 2 coaxially sleeved, a support ring 3 is respectively sealed and welded between the left and right ends of the outer tube 2 and the inner tube 1, and a vacuum joint 4 is sealed and welded on the outer tube 2. Among them, the inner tube 1 is made of low-expansion alloy steel 4J36, and the outer tube 2, the support ring 3 and the vacuum joint 4 are made of stainless steel. Through the above settings, a low-temperature vacuum straight tube without compensation is formed. Compared with the existing low-temperature vacuum tube with a bellows compensator, the present invention makes the inner tube 1 made of low-expansion alloy steel 4J36, and utilizes its low expansion coefficient characteristics. It can adapt to the thermal expansion and contraction caused by the temperature difference without setting a bellows compensator, which not only simplifies the structure, reduces the manufacturing difficulty and cost, but also does not generate a large load on the pipelines at both ends, and does not need to set an additional support structure; by making the outer tube 2, the support ring 3 and the vacuum joint 4 made of stainless steel, the corrosion resistance is improved and the service life is extended. It should be noted that the vacuum joint is an existing component in the field, and its structure and principle are well known to technicians.

[0028] As an optimization solution, in this specific embodiment, a vacuum adsorption box 11 is welded on the outer wall of the inner tube 1, and an adsorbent is arranged in the vacuum adsorption box 11. This structure can maintain a reliable high vacuum degree in the vacuum chamber for a long time by arranging the vacuum adsorption box 11 and the adsorbent, and using the adsorbent to adsorb the gas leaked in the vacuum chamber (the space between the inner and outer tubes), thereby improving the maintenance convenience of the vacuum straight tube. In practical applications, the present invention usually uses 5A molecular sieve as an adsorbent, but is not limited to 5A molecular sieve, and other substances with equivalent functions can also be used as adsorbents, which can also achieve the technical purpose of the present invention. At the same time, in order to ensure the effectiveness and reliability of the adsorbent, the present specific embodiment provides an adsorbent filling port and a matching plug 12 on the vacuum adsorption box 11, and provides a filling operation hole corresponding to the adsorbent filling port and a matching cover 5 on the outer tube 2, so that the adsorbent can be filled into the vacuum adsorption box 11 when the vacuum straight tube is assembled. Specifically, firstly, the vacuum adsorption box 11 and two support rings 3 are welded on the inner tube 1, and the left and right ends of the outer tube 2 are welded to the two support rings 3, and the vacuum joint 4 is welded on the outer tube 2; then, the adsorbent is filled into the vacuum adsorption box 11 through the filling operation hole and the adsorbent filling port, and after the filling is completed, the adsorbent filling port is sealed by the plug 12, and the cover 5 is sealed and welded at the filling operation hole; then, the vacuum operation is performed through the vacuum joint 4, and the vacuum joint 4 is closed after the vacuum is completed. It should be noted that the vacuum adsorption box 11 specifically includes two annular side plates welded on the inner tube 1 and a cylindrical arc plate welded on the two annular side plates, and the cylindrical arc plate is provided with adsorption holes arranged dispersedly.

[0029] As an optimization solution, in order to reduce the heat exchange between the inner tube 1 and the outer tube 2 and avoid deformation of the outer tube 2 due to low temperature, the present embodiment coats the outer wall of the inner tube 1 with an insulating layer 6 made of insulating material to achieve the purpose of low heat leakage. Similarly, the present embodiment also coats the vacuum adsorption box 11 with an insulating layer 13 made of insulating material. In practical applications, the present invention generally uses a composite material composed of alkali-free glass fiber cloth, alkali-free glass fiber tape, and aluminum foil as an insulating material to ensure the insulation effect, but is not limited to the above-listed forms, and other forms of insulating materials can also be used. In order to improve the stability of the structure, the present embodiment also fixes a support member 7 made of low heat leakage material on the outer wall of the inner tube 1. As a specific way of fixing, the present invention allows the support member 7 to be sleeved on the inner tube 1, and a retaining ring welded on the inner tube 1 and made of stainless steel is provided on both sides of the support member 7, so that the support member 7 can be clamped and fixed by two retaining rings. In practical applications, the present invention generally uses polytetrafluoroethylene or epoxy fiberglass as low heat leakage materials, but is not limited to the above-listed forms. Other forms of low heat leakage materials can also be used to achieve the technical purpose of the present invention. As an optimization scheme, in order to facilitate the combination of multiple low-temperature vacuum straight tubes into a long-distance low-temperature vacuum pipeline, the present specific implementation seals and welds the left connecting ring 8 and the right connecting ring 9 on the outer wall of the outer tube 2. In this way, through the sealing and welding of the connecting tube corresponding to the left connecting ring 8 and the right connecting ring 9 on the adjacent low-temperature vacuum straight tube, multiple low-temperature vacuum straight tubes can be sealed and welded into a long-distance low-temperature vacuum pipeline, thereby improving the convenience of welding. In practical applications, the present invention makes the left connecting ring 8 and the right connecting ring 9 made of stainless steel to improve its corrosion resistance.

[0030] Based on the same concept, the present invention also provides a method for preparing the above-mentioned low-temperature vacuum straight tube, comprising the following steps:

[0031] S1. Weld the vacuum adsorption box 11 and two support rings 3 to the inner tube 1 respectively, wherein the vacuum adsorption box 11 is provided with an adsorbent filling port.

[0032] S2. After the inner tube 1 is coated with a heat insulating layer 6 using a heat insulating material, the left and right ends of the outer tube 2 are welded to the two support rings 3 correspondingly, wherein a filling operation hole is provided on the outer tube 2.

[0033] S3, respectively weld the vacuum joint 4, the left connecting ring 8 and the right connecting ring 9 to the outer tube 2.

[0034] S4, filling the vacuum adsorption box 11 with adsorbent through the filling operation hole and the adsorbent filling port. After the filling is completed, the adsorbent filling port is sealed with the plug 12, and the cover 5 is sealed and welded at the filling operation hole.

[0035] S5, performing a vacuuming operation through the vacuuming joint 4, and closing the vacuuming joint 4 after the vacuuming is completed.

[0036] In order to improve the stability of the structure, in step S1, before welding the two support rings 3, an operation of installing the support member 7 on the inner tube 1 is performed, which includes the following steps:

[0037] S1-1, a support member 7 and two retaining rings correspondingly located on both sides of the support member 7 are sleeved on the inner tube 1.

[0038] S1-2, make two retaining rings clamp the support member 7 and weld them to the inner tube 1 respectively.

[0039] The preparation method of the low-temperature vacuum straight tube provided by the invention has the advantages of simple process and convenient operation.

[0040] Practical application shows that the low-temperature vacuum straight tube that does not require compensation and the preparation method thereof provided by the present invention can produce the following beneficial effects: 1. The present invention makes the inner tube made of low-expansion alloy steel 4J36 (i.e., Invar steel), and there is no need to use a bellows compensator, which greatly simplifies the low-temperature vacuum pipeline structure; 2. The present invention reduces the use of supports and reduces heat leakage through the vacuum interlayer design of welding support rings at both ends of the inner and outer tubes, and ensures high vacuum life through the vacuum adsorption box and adsorbent, thereby improving the convenience of vacuum maintenance; 3. In the present invention, since the expansion coefficient of the inner tube is relatively low, the load on the support ring can be effectively reduced in practical applications, reducing the influence of low-temperature stress and improving the reliability under low-temperature conditions.

[0041] The above embodiments are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the protection scope of the present invention. Without departing from the design concept of the present invention, various modifications made by those skilled in the art based on the technical solution of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A low-temperature vacuum straight tube without compensation, characterized in that: The invention comprises an inner tube (1) and an outer tube (2) which are coaxially sleeved, support rings (3) are respectively welded between the left and right ends of the outer tube (2) and the inner tube (1), and a vacuum joint (4) is welded on the outer tube (2). The inner tube (1) is made of low expansion alloy steel 4J36, and the outer tube (2), the support ring (3) and the vacuum joint (4) are made of stainless steel.

2. The low-temperature vacuum straight tube without compensation according to claim 1, characterized in that: A vacuum adsorption box (11) is welded on the outer wall of the inner tube (1), and an adsorbent is arranged in the vacuum adsorption box (11).

3. The low-temperature vacuum straight tube without compensation according to claim 2, characterized in that: The vacuum adsorption box (11) is provided with an adsorbent filling port and a matching plug (12), and the outer tube (2) is provided with a filling operation hole corresponding to the adsorbent filling port and a matching sealing cover (5).

4. The low-temperature vacuum straight tube without compensation according to claim 3, characterized in that: The outer wall of the inner tube (1) is coated with a heat insulating layer (6) made of a heat insulating material.

5. The low-temperature vacuum straight tube without compensation according to claim 4, characterized in that: A support member (7) made of a low heat leakage material is fixed on the outer wall of the inner tube (1).

6. The low-temperature vacuum straight tube without compensation according to claim 5, characterized in that: A left connecting ring (8) and a right connecting ring (9) are seal-welded on the outer wall of the outer tube (2).

7. The low-temperature vacuum straight tube without compensation according to claim 6, characterized in that: The support member (7) is sleeved on the inner tube (1), and retaining rings welded to the inner tube (1) are provided on both sides of the support member (7).

8. The low-temperature vacuum straight tube without compensation according to claim 6, characterized in that: The left connecting ring (8) and the right connecting ring (9) are made of stainless steel.

9. A method for preparing the low-temperature vacuum straight tube according to claim 6, characterized in that: The following steps are involved: S1. Welding the vacuum adsorption box (11) and the two support rings (3) onto the inner tube (1) respectively, wherein the vacuum adsorption box (11) is provided with an adsorbent filling port; S2. After the inner tube (1) is coated with a heat insulating layer (6) using a heat insulating material, the left and right ends of the outer tube (2) are welded to the two support rings (3) respectively, wherein a filling operation hole is provided on the outer tube (2); S3, welding the vacuum joint (4), the left connecting ring (8) and the right connecting ring (9) to the outer tube (2) respectively; S4, filling the adsorbent into the vacuum adsorption box (11) through the filling operation hole and the adsorbent filling port, sealing the adsorbent filling port through the plug (12) after the filling is completed, and sealing the cover (5) at the filling operation hole; S5, performing a vacuuming operation through the vacuuming joint (4), and closing the vacuuming joint (4) after the vacuuming is completed.

10. The method for preparing a low-temperature vacuum straight tube according to claim 9, characterized in that: In step S1, before welding the two support rings (3), an operation of installing a support member (7) on the inner tube (1) is performed, which includes the following steps: S1-1, sleeve a support member (7) and two retaining rings located on both sides of the support member (7) on the inner tube (1); S1-2, making two retaining rings clamp the support member (7) and weld them to the inner tube (1) respectively.

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