A welding structure of a plate-fin reactor

Abstract

The invention discloses a welding structure of a plate-fin reactor, comprising alternately arranged partitions and fins and a plurality of seals, wherein the seal is a T-shaped structure with a tongue-and-groove structure composed of horizontal and vertical sides, a groove and a tenon are respectively arranged on the left and right sides of the horizontal side, two adjacent horizontal sides are inlaid by the groove and the tenon, the vertical side on the lower side of the horizontal side is overlapped between two adjacent partitions, the bottom of the vertical side is in contact with the fin, a brazing material is arranged between the left and right sides and the partition, the horizontal side is in contact with a welding head, and a molten weld is formed between the welding head and the seal; the patent uses a T-shaped seal with a tongue-and-groove structure for welding structure design, which can effectively avoid the problem of cracking of the brazing seam along the head direction when the vacuum brazing plate-fin reactor seal and the head are melt-welded, thereby improving the welding quality and production efficiency.

Description

Technical Field

[0001] The invention relates to a welding structure, in particular to a welding structure for vacuum brazing a sealing strip and a sealing head of a plate-fin reactor. Background Art

[0002] The core of the plate-fin heat exchanger is made up of partitions, seals and fins stacked in sequence. Amorphous thin strip brazing material or paste brazing material is usually placed between the partitions and seals, and between the partitions and fins, and is compacted and brazed together in a vacuum furnace. It has been widely used in engineering due to its compact structure, large heat exchange area, and high heat exchange efficiency.

[0003] The plate-fin reactor based on the plate-fin heat exchanger is filled with catalysts between the fins, and heat coupling reactions occur between different flow channels. Due to the high reaction temperature and pressure, the reactor material is made of austenitic stainless steel, and the brazing material is made of high-temperature nickel-based brazing material. Nickel-based brazing material has the advantages of anti-oxidation, high brazing joint strength, corrosion resistance, and good high-temperature performance. Currently, the more common nickel-based brazing materials are mainly Ni-Cr-Si and Ni-Cr-B-Si brazing materials. The main function of Si and B is to reduce the melting point of the brazing material, but these two alloy elements are more likely to form brittle compounds during the brazing process, which reduces the toughness of the brazing seam and there is a risk of welding cracks.

[0004] In the existing plate-fin reactor welding structure, after the core is brazed, the head is welded by fusion welding. The direction of the head is perpendicular to the direction of the brazing seam. The fusion welding seam will damage the existing brazing seam. Specifically, the fusion welding is in direct contact with the brazing seam, and the instantaneous high temperature causes the brazing seam to melt locally. After the brazing seam is cooled, it may not be fused, causing medium leakage; the brittle compounds formed by Si and B elements in the nickel-based brazing material are easily cracked along the brazing seam direction under the influence of the thermal stress generated by the fusion welding. At the same time, these two elements will also have an adverse effect on the quality of the fusion weld.

[0005] The commonly used solution is to use molten weld to repair the brazing seam. The problems are: on the one hand, during the repair welding process, brittle cracks tend to extend continuously along the molten weld, resulting in the extension of the repair weld, large welding workload, and high production and processing costs; on the other hand, the stop point of the repair welding is also the intersection of the molten weld and the brazing seam. The original brazing seam may be affected by high temperature and may produce internal defects such as unfused and pores. During the operation of the reactor, there is a risk of further cracking, which reduces the reliability of the reactor. Summary of the invention

[0006] In order to solve the technical problems existing in the background technology, the present invention provides a welding structure of a seal and a head of a vacuum brazed plate-fin reactor to avoid the problem of cracking of the brazing seam along the head direction when the seal and the head are melt-welded in the core of the vacuum brazed plate-fin reactor.

[0007] The technical solution adopted by the present invention to solve its technical problems is: a welding structure of a plate-fin reactor, including alternately arranged partitions and fins, and a seal connected to the partition, wherein there are multiple seals, and the seal is a T-shaped structure with a tongue and groove structure composed of horizontal and vertical sides, and the left and right sides of the horizontal side are respectively provided with grooves and tenons, and two adjacent horizontal sides are embedded through the grooves and tenons, and the vertical side on the lower side of the horizontal side is overlapped between two adjacent partitions, and the bottom of the vertical side is in contact with the fins, and brazing filler metal is provided between the left and right sides of the vertical side and the partition, and the horizontal side of the seal away from the fin is in contact with the welding head, and there is a molten weld between the welding head and the seal.

[0008] The solder of the welding structure of the plate-fin reactor is an amorphous thin strip solder or a paste solder.

[0009] The welding structure of the plate-fin reactor is preferably made of BNi2 with a thickness of 80 to 120 um.

[0010] The welded structure of the plate-fin reactor has a preferred height range of 3 to 5 mm for the horizontal side and a preferred height range of 8 to 16 mm for the vertical side.

[0011] The groove of the welding structure of the plate-fin reactor is a dovetail groove, or a tongue-and-groove of other structures. Preferably, the angle between the vertical side and the oblique side of the dovetail groove is 40-60°, and the height of the vertical side is 1-2 mm.

[0012] The welding structure of the plate-fin reactor has a welding head and a sealing strip made of austenitic stainless steel, including 304 and 316, which are welded into a whole by argon arc welding or laser welding.

[0013] The welding structure of the plate-fin reactor has a partition plate which is an austenitic stainless steel flat plate with uniform thickness.

[0014] The welding structure of the plate-fin reactor has fins with a cross-section of an I-shaped shape, which are usually formed by stamping using a mold. To enhance heat transfer, the fins can be punched with small holes, and the preferred material is austenitic stainless steel or oxygen-free copper.

[0015] The beneficial effects of the present invention are:

[0016] 1. Compared with the commonly used I-shaped structure, the T-shaped seal separates the molten weld from the brazing seam through the horizontal edge, thereby reducing the impact of high temperature on the brazing seam.

[0017] 2. The tongue and groove structure on the left and right sides of the seal can effectively prevent the brazing material from extending along the contact surface to the outer surface of the seal, and reduce the adverse effects of the brittle compounds formed by Si and B elements on fusion welding and brazing seams.

[0018] 3. Through the patented welding structure design, the problem of cracking of the brazing seam along the head during the melting welding of the seal strip and the head can be effectively avoided, thereby improving production efficiency and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the welding structure of the present invention;

[0020] Figure 2 It is a schematic diagram of the structure of a T-shaped seal with a tongue and groove structure of the present invention.

[0021] The reference numerals of the figures are: 1—welding head, 2—seal strip, 21—groove, 22—horizontal edge, 23—tenon, 24—vertical edge, 3—solder, 4—melted weld, 5—partition plate, 6—fin. DETAILED DESCRIPTION

[0022] To further illustrate the purpose and technical solution of the present invention, the present invention will be further described in detail below in conjunction with the specific embodiments of the accompanying drawings. The following embodiments are only used to explain the present invention and do not constitute a limitation of the present invention.

[0023] Reference Figure 1 , Figure 2As shown, the welding structure of a plate-fin reactor disclosed in the present invention comprises a partition plate 5 and a fin 6 arranged alternately, and a seal 2 connected to the partition plate 5, a partition plate 5 is arranged between the seals 2 and the seals 2, and a fin 6 is arranged between the partition plates 5 and the partition plates 5. The seals 2, the partition plates 5, the fins 6 and the brazing material 3 are vacuum brazed to form a reactor core, the partition plate 5 is an austenitic stainless steel flat plate with uniform thickness, there are a plurality of seals 2, and the seal 2 is a T-shaped structure with a tongue-and-groove structure composed of a horizontal side 22 and a vertical side 24, the left and right sides of the horizontal side 22 are respectively provided with a groove 21 and a tenon 23, and two adjacent horizontal sides 22 are embedded by the groove 2 and the tenon 23. Compared with the traditional I-shaped seal, the T-shaped seal 2 with a tongue-and-groove structure is composed of a horizontal side 22 and a vertical side 24. The preferred height range of the horizontal side 22 is 3-5mm, the preferred height range of the vertical side 24 is 8-16mm, the groove 21 is a dovetail groove, and can also be a mortise and tenon groove of other structures. The preferred dovetail groove has an angle range of 40-60° between the vertical side and the hypotenuse, and a vertical side height range of 1-2mm. The vertical side 24 on the lower side of the horizontal side 22 is overlapped between two adjacent partitions 5, and the bottom of the vertical side 24 is in contact with the fin 6. The fin 6 is a fin with a "J"-shaped cross-section, which is usually formed by stamping a mold. To enhance heat transfer, the fin can be punched with small holes. The preferred material is austenitic stainless steel or oxygen-free copper. A brazing material 3 is arranged between the left and right sides of the vertical side 24 and the partition 5. The horizontal side 22 of the seal 2 away from the fin 6 is in contact with the welding head 1, and a molten weld 4 is provided between the welding head 1 and the seal 2 of the core.

[0024] The solder 3 is an amorphous thin strip solder or a paste solder, preferably made of BNi2 with a thickness of 80 to 120 um. The welding head 1 and the seal 2 are made of austenitic stainless steel, including 304 and 316, and are welded into a whole by argon arc welding or laser welding to provide a flow channel for the medium, and the molten weld runs across the upper side of the horizontal edge 22.

[0025] The assembly and welding sequence is as follows:

[0026] First, evenly place BNi2 amorphous thin strip solder 3 or paste solder 3 on the partition 5, then place fins 6 and T-shaped seals 2 on the solder 3, and continue to evenly place solder 3 on the vertical sides 24 of the T-shaped seal 2 and the sides of the fins 6 to form a basic unit. According to the design requirements, several basic units are stacked in sequence to form the core of the plate-fin reactor.

[0027] Use a special clamp to apply 5-8MPa pressure on the core. After clamping, the core and the clamp are placed in a vacuum brazing furnace for brazing. The step-by-step heating method is adopted, and the maximum welding temperature is about 1040℃. After that, it is taken out of the furnace at 30-50℃ while cooling down, and the core brazing is completed.

[0028] Use argon arc welding or laser welding and a suitable welding process to weld the welding head 1 and the core body into one, and form a molten weld 4 on the contact surface between the T-shaped head 2 and the welding head 1. After welding, the brazing seam remains intact without cracking. After passing the pressure resistance and air tightness tests, the brazing seam and the molten weld meet the reactor use requirements.

[0029] It is easy for those skilled in the art to understand that the above description is only a preferred use case of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A welded structure of a plate-fin reactor, comprising alternately arranged baffles (5) and fins (6), and a seal (2) connected to the baffles (5), characterized in that: There are a plurality of seals (2), and the seal (2) is a T-shaped structure consisting of a horizontal side (22) and a vertical side (24). The left and right sides of the horizontal side (22) are respectively provided with a groove (21) and a tenon (23). Two adjacent horizontal sides (22) are embedded through the groove (21) and the tenon (23). The vertical side (24) overlaps between two adjacent partitions (5). The bottom of the vertical side (24) contacts the fin (6). Brazing material (3) is provided between the left and right sides of the vertical side (24) and the partition (5). The horizontal side (22) contacts the welding head (1). A molten weld (4) is provided between the welding head (1) and the seal (2).

2. A welding structure of a plate-fin reactor according to claim 1, characterized in that: The solder (3) is an amorphous thin strip solder or a paste solder.

3. A welding structure of a plate-fin reactor according to claim 2, characterized in that: The solder (3) is made of BNi2 and has a thickness of 80 to 120 μm.

4. The welding structure of a plate-fin reactor according to claim 1, characterized in that: The height of the horizontal side (22) is 3 to 5 mm, and the height of the vertical side (24) is 8 to 16 mm.

5. The welding structure of a plate-fin reactor according to claim 4, characterized in that: The groove (21) is a dovetail groove, the included angle between the vertical side and the oblique side of the dovetail groove is 40 to 60 degrees, and the height of the vertical side is 1 to 2 mm.

6. A welding structure of a plate-fin reactor according to any one of claims 1 to 5, characterized in that: The welding head (1) and the sealing strip (2) are made of austenitic stainless steel and are welded into a whole by argon arc welding or laser welding.

7. A welding structure of a plate-fin reactor according to any one of claims 1 to 5, characterized in that: The partition plate (5) is an austenitic stainless steel flat plate with uniform thickness.

8. A welding structure of a plate-fin reactor according to any one of claims 1 to 5, characterized in that: The fin (6) has an I-shaped cross section and is made of austenitic stainless steel or oxygen-free copper.

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