Preparation method of flue gas bipolar heat exchanger for radiant tube burner

Abstract

The present invention discloses a preparation method of a flue gas bipolar heat exchanger for a radiant tube burner. The three assemblies of an internal fin tube assembly, a flue gas chamber assembly, and an air inlet pipe assembly are independently assembled and welded. After welding, each of them is subjected to airtightness detection. Then, the flue gas chamber assembly is first inserted into the internal fin tube assembly; then, the flue gas chamber assembly is connected to the connecting flange, and the flange of the air inlet pipe assembly is connected to the outside of the connecting flange on the outside of the connecting flange to complete the assembly. The manufacturing process of the present invention is simple and efficient, and the processes are not mutually restrained. The production is flexible and mobile, and the overall process will not be affected by the stagnation of one process; the delivery status of the finished product is flexible and changeable, and it can be assembled in the manufacturing plant and transported to the installation site, or it can be packaged and transported according to the assembly classification, and flexibly assembled at the installation site; the technical key points are clear and controllable, which greatly improves the production efficiency and product quality; the process assembly welding process has high production efficiency, and 5 people / 16 shifts can achieve 100 units.

Description

Technical Field

[0001] The invention relates to a method for preparing a flue gas bipolar heat exchanger for a radiant tube burner, and belongs to the technical field of heat exchangers. Background Art

[0002] Heat exchanger is a general equipment widely used in chemical industry, oil refining, metallurgy, power, light industry, atomic energy, pharmaceutical, machinery and many other industrial fields. According to different industrial furnace equipment, a variety of flue gas bipolar waste heat exchangers for radiant tube burners are designed.

[0003] In recent years, my country and other countries in the world have continuously increased their requirements for product quality, waste heat recovery and control technology, especially for environmental protection such as pollutant emissions. Radiant tube heating technology has also been continuously promoted and improved. Accumulating production and manufacturing experience and improving heat exchanger manufacturing processes to improve production efficiency and reduce production costs are the research and development directions in the field of radiant tube heater manufacturing technology.

[0004] As applied by our company: 202111463320.7, a manufacturing process of a flue gas bipolar heat exchanger for a radiant tube burner discloses: 1. Assembly and welding of each component: (1) Assembly welding of fin tube group; (2) Assembly welding of internal and external heat exchange air ducts and jet reducer; (3) Assembly welding of air combustion air duct; (4) Assembly welding of air heat exchange tube; (5) Assembly welding of combustion air sleeve; (6) Assembly welding of special-shaped flange and drainage support plate; (7) Assembly welding of flue gas cavity; 2. Assembly of internal heat exchange assembly Welding: (1) Take the internal and external heat exchange ducts and jet reducer assembly welded in steps 1 and (2), and insert the internal heat exchange duct section into the fin tube assembly; this weld H1 (2) inserts the welded air combustion-supporting duct into the welded air heat exchange tube; (3) Take the special-shaped flange and the drainage support plate assembly and the connecting pipe welded in steps 1 and (6) and put them on the external heat exchange duct, then connect the interlaced semicircle R1 of the external heat exchange duct with the interlaced semicircle R2 of the air heat exchange tube, so that the vertical pipe end of the air combustion-supporting duct assembly is interlaced The interlaced semicircle R1 and the interlaced semicircle R2 are coaxial, and the connecting pipe is provided with an interlaced semicircle R4; (4) Unified welding welds B2, H1, H2, H3; III. External assembly welding: (1) The smoke cavity tube is placed outside the air heat exchange tube, and the flange II is parallel to the axis. The distance L1 between the branch pipe and the vertical pipe is adjusted to meet the drawing size. The interlaced semicircle R3 of the smoke cavity tube 7-3 and the interlaced semicircle R4 of the connecting pipe 8 are butt-welded, and the weld here is H5; (2) Place the special-shaped flange vertically on the horizontal fixing fixture, then put the combustion-supporting air sleeve on the vertical pipe of the air combustion-supporting air duct, and adjust the distance L2 between the vertebral tube and the special-shaped flange, and the distance L3 between the special-shaped flange and the vertical pipe to meet the drawing dimensions. Then, spot weld and fix the weld H4 between the special-shaped flange and the connecting pipe, spot weld and fix the weld H6 between the steel pipe and the flue gas cavity pipe, and spot weld and fix the weld H7 between the vertical pipe and the flange; (3) Unify the welding of welds H4, H5, H6, and H7, and the flue gas bipolar heat exchanger assembly welding is completed.

[0005] Among them, we divided the product into 7 parts for independent welding, and finally assembled and welded each part in two steps. In order to further meet customer needs, we found that the existing production process still has the following problems:

[0006] 1. There is still room for research and development in the production process, and the productivity and delivery time of shift personnel still need to be improved;

[0007] 2. The delivery status of finished products is not flexible enough, and it is impossible to package and transport them according to the assembly parts, and flexibly assemble them at the installation site;

[0008] 3. The selection of welding position is not flexible enough, and cannot meet the overall requirements of small and controllable welding deformation variables, as well as high production efficiency and product quality. Summary of the invention

[0009] In order to overcome the above difficulties, our company organized a research and development team to discuss and finally decided to design a preparation method for flue gas bipolar heat exchanger for radiant tube burners, which is simple, efficient and can effectively guarantee product quality.

[0010] To achieve the above-mentioned purpose, the technical means adopted by the present invention are: a method for preparing a flue gas bipolar heat exchanger for a radiant tube burner, wherein the three assemblies of an internal fin tube assembly, a flue gas chamber assembly, and an air inlet pipe assembly are independently assembled and welded, and each of them is subjected to an airtightness test after welding. Then, the flue gas chamber assembly is first inserted into the internal fin tube assembly; then, the flue gas chamber assembly is connected to the connecting flange, and the flange of the air inlet pipe assembly is connected to the outside of the connecting flange on the outside of the connecting flange to complete the assembly.

[0011] Furthermore, the internal fin tube assembly includes a hot air tube, a primary fin tube, and a secondary fin tube, wherein the hot air tube is assembled and welded in sequence from a hot air straight tube, an elbow, and a spinal tube; a groove is processed at one end of the hot air straight tube for connection with one end of the elbow, and the other end of the hot air straight tube is perpendicular to the spinal tube port;

[0012] The secondary fin tube comprises a plurality of fin tube fittings, a secondary fin large diameter tube, a toothed sealing plate and a secondary fin small diameter tube, which are assembled and welded in sequence to form a plug tube, and the three parts are on the same axis, and the secondary fin small diameter tube is perpendicular to the toothed sealing plate, and the secondary fin large diameter tube is located at one end of the toothed sealing plate and processed with a groove, and a plurality of fin tube fittings are sequentially sleeved on the outer wall of the secondary fin small diameter tube, and then assembled and welded, and the components are on the same axis, and all welds are closed welds;

[0013] The first-level fin tube includes a plurality of fin tube fittings and a fin tube head. After the plurality of fin tube fittings and the fin tube head are assembled, welding is completed; each component has the same axis, and all welds are closed welds;

[0014] Insert the hot air pipe into the perforated steel pipe II, assemble it with the perforated steel pipe I, and then assemble it with the secondary finned tube and the primary finned tube with tooling and then weld it; install the secondary finned tube flange on the end of the secondary finned large diameter tube; process the grooves on the ends of the perforated steel pipe I and the perforated steel pipe II, and the arc of the opening is consistent with the arc of the horizontal insertion of the elbow; all components have the same axis.

[0015] Furthermore, the weld between the perforated steel tube I and the perforated steel tube II is first welded, and the weld is welded from the lower opening to the non-opening direction, and the weld is symmetrically welded on both sides, so that the internal fin tube group is deformed in the opposite direction of the weld at the opening; then the weld between the perforated steel tube I and the first-level fin tube, and the weld between the perforated steel tube II and the second-level fin tube are welded. When the weld between the perforated steel tube I and the perforated steel tube II drops to room temperature, the weld at the opening is welded, and all welds are closed welds; after the internal fin tube assembly is welded, the linear value is first tested, and the previous weld is calibrated to meet the linear tolerance, and then the tooling is put back and assembled with the second-level fin tube flange for positioning and welding. The plane of the second-level fin tube flange must be perpendicular and coaxial to the axial direction of the internal fin tube assembly; finally, an airtightness test is performed, and there is no leakage under this set condition.

[0016] Furthermore, the smoke chamber assembly includes a smoke main pipe, a smoke main pipe flange I, a smoke main pipe flange II, a smoke branch pipe, and a smoke branch pipe flange. The smoke main pipe flange I, the smoke main pipe flange II and the two ends of the smoke main pipe are assembled and welded by using a tool; after the weldment shrinks and sets due to heat, the smoke branch pipe is assembled and welded; the smoke branch pipe flange is assembled and welded to the smoke branch pipe by using a tool; and then the test pipe and the sealing screw nut are assembled and welded;

[0017] The welding seams between the flue gas main pipe and the flue gas main pipe flange I and the flue gas main pipe flange II are welded. The flanges of the two flue gas chamber components are fastened with bolts and then welded so that the welding stresses on both sides are restrained from each other. The welds between the flue gas main pipe and the flue gas branch pipe are of the minimum fillet weld size. Finally, an airtightness test is performed, and there is no leakage under the set conditions.

[0018] Furthermore, the air inlet pipe assembly includes an air intake straight pipe I, an air intake elbow, and an air intake straight pipe II. The air intake straight pipe I, the air intake elbow, and the air intake straight pipe II are first assembled and welded; then the air inlet pipe flange I, the air inlet pipe flange II, and the ends of the air intake straight pipe I and the air intake straight pipe II are respectively assembled and welded using tooling. The center line and axis of the flange must be vertical. Finally, an air tightness test is performed, and there is no leakage under the set conditions.

[0019] Furthermore, the smoke chamber assembly is inserted into the secondary fin tube end of the internal fin tube assembly; then the sealing gasket is placed between the connecting flange and the secondary fin tube flange, and fastened with countersunk screws; the smoke chamber assembly is connected to the connecting flange; on the outside of the connecting flange, the sealing gasket is placed between the air inlet pipe flange and the outside of the connecting flange, and fastened with bolts, nuts and gaskets; the assembly flange connections of all components meet the sealing requirements.

[0020] The beneficial effects of the present invention are:

[0021] 1. The product is divided into 3 components, which are assembled and welded independently, and then connected and assembled to complete the manufacture of the heat exchanger; the manufacturing process is simple and efficient, and the processes are not mutually restrained, the production is flexible and mobile, and the overall process will not be affected by the stagnation of one process;

[0022] 2. The delivery status of finished products is flexible and changeable. They can be assembled in the manufacturing plant and transported to the installation site, or they can be packaged and transported according to the assembly parts and assembled flexibly at the installation site.

[0023] 3. The technical key points are clear and controllable, that is, the plane of the secondary fin tube flange must be perpendicular and coaxial to the axial direction of the fin tube assembly. The air inlet pipe assembly and the smoke chamber assembly are connected with the secondary fin tube flange as the base. The welding position selection is flexible, which improves the weld quality. The deformation variable caused by welding is small and controllable, which greatly improves the production efficiency and product quality.

[0024] 4. The process of process assembly and welding has high production efficiency, and 5 people / 19 shifts can produce 100 units. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0026] Figure 1 It is a schematic diagram of the welding structure of the hot air pipe;

[0027] Figure 2 It is a schematic diagram of the steel pipe toothed sealing plate and assembly welding;

[0028] Figure 3 It is a schematic diagram of the steel pipe toothed sealing plate and the assembly welding in the A direction;

[0029] Figure 4 It is a schematic diagram of the welding of the secondary fin tube;

[0030] Figure 5 It is a schematic diagram of the welding of the first-level fin tube;

[0031] Figure 6 It is a schematic diagram of the welding of the internal fin tube group;

[0032] Figure 7 It is the A-direction schematic diagram of the internal fin tube group;

[0033] Figure 8 It is the process diagram of the airtight leakage detection of the internal fin tube group;

[0034] Fig. 9 It is a schematic diagram of the welding of the smoke chamber;

[0035] Fig.10 It is a schematic diagram of the welding of the smoke chamber in the A direction;

[0036] Fig.11This is a schematic diagram of the welding of the air inlet pipe;

[0037] Fig.12 It is a schematic diagram of the connecting flange;

[0038] Fig.13 It is a schematic diagram of the finished assembly of the heat exchanger;

[0039] The following are marked in the figure: 1. hot air pipe, 11. hot air straight pipe, 12. elbow, 13. spinal tube; 2. secondary finned tube, 21. secondary finned large diameter tube, 22. toothed sealing plate, 23. secondary finned small diameter tube, 24. finned tube fittings; 3. primary finned tube group, 31. finned tube fittings, 32. finned tube head; 4. internal finned tube assembly, 41. perforated steel tube I, 42. perforated steel tube II, 43. secondary finned tube flange; 5. smoke chamber assembly, 51 , flue gas main flange I; 52, flue gas main, 53, flue gas main flange II, 54, flue gas branch pipe, 55, flue gas branch pipe flange, 56, test tube and sealing nut; 6, air inlet connecting pipe assembly, 61, steel pipe 4; 62, elbow 2; 63, steel pipe 5; 64, flange 5; 65, flange 6; 7, connecting flange; 71, countersunk process hole; 72, straight screw hole; 73, flange hole; 8, sealing gasket I; 9, sealing gasket II. DETAILED DESCRIPTION

[0040] Example 1

[0041] A preparation method of a flue gas bipolar heat exchanger for a radiant tube burner comprises the following steps: the three components of an internal fin tube component, a flue gas chamber component and an air inlet pipe assembly are independently assembled and welded, and each component is subjected to airtightness testing after welding. Then, the flue gas chamber component is first inserted into the internal fin tube component; the flue gas chamber component is then connected to a connecting flange, and the flange of the air inlet pipe assembly is connected to the outer side of the connecting flange on the outer side of the connecting flange to complete the assembly.

[0042] Assembly welding of the internal fin tube assembly 4: The internal fin tube assembly 4 includes a hot air tube 1, a primary fin tube 3, and a secondary fin tube 2;

[0043] like Figure 1 As shown, the hot air pipe 1 is first welded together. The hot air pipe 1 is assembled and welded in sequence by a hot air straight pipe 11, an elbow 12, and a vertebral tube 13; Figure 1 As shown, the end a of the hot air straight pipe 11 is processed with a groove for connecting with one end of the elbow 12, and the end b of the hot air straight pipe 11 is perpendicular to the end of the vertebral tube 13;

[0044] like Figure 2 , Figure 3As shown, the secondary fin tube 2 includes a plurality of fin tubes 24, a secondary fin large diameter tube 21, a toothed sealing plate 22 and a secondary fin small diameter tube 23, which are assembled and welded in sequence to form a plug tube, and the three parts are on the same axis, and the secondary fin small diameter tube 23 is perpendicular to the toothed sealing plate 22, and the secondary fin large diameter tube 21 is located at one end of the toothed sealing plate 22 and the groove is processed; the second step, as shown in FIG. Figure 4 As shown, a plurality of finned tubes 24 are sequentially sleeved on the outer wall of the secondary finned small-diameter tube 23, and then assembled and welded. Each component has the same axis, and all welds are closed welds.

[0045] like Figure 5 As shown, the primary fin tube 3 includes a plurality of fin tube fittings 31 and a fin tube head 32. After the plurality of fin tube fittings 31 and the fin tube head 32 are assembled, welding is completed; each component has the same axis, and all welds are closed welds;

[0046] Insert the hot air pipe 1 into the perforated steel pipe II42, assemble it with the perforated steel pipe I41, and then assemble it with the secondary finned tube 2 and the primary finned tube 3 with a tool and weld them; install the secondary finned tube flange 43 on the end of the secondary finned large diameter tube; assembly requirements: Figure 7 As shown, the secondary fin tube flange 43 is evenly processed with screw holes, the ends of the perforated steel pipes I and II are processed with grooves, and the arc of the opening is consistent with the arc of the horizontal insertion of the elbow 12; all components have the same axis; the L1 dimension meets the tolerance of ±1mm in the drawing.

[0047] Welding process: A10 weld is an asymmetric weld located on the perforated steel pipe. After welding, stress concentration will inevitably cause the two ends of the internal fin tube group to warp, so the "anti-deformation welding" sequence must be adopted: first weld the A7 weld, and weld from W1 to W2, and the other side of the A7 weld is also the same, so that the internal fin tube group deforms in the opposite direction of the A10 weld; then weld the A8 and A9 welds, at which time the A7 weld has dropped to room temperature; finally weld the A10 weld, and its concentrated welding tensile stress will "straighten" the warping of the two ends of the internal fin tube group or approach the linear requirements, thereby reducing or avoiding the workload of shape correction; all welds are closed welds;

[0048] like Figure 6 As shown, after welding the internal fin tube assembly, first check the linear value, and properly correct the previous weld to meet the linear tolerance, and then put it back into the tooling and position and assemble it with the secondary fin tube flange 43 for welding. Technical requirements: The plane of the secondary fin tube flange 43 must be perpendicular and coaxial to the axial direction of the fin tube assembly; the L2 dimension must meet the tolerance of ±1mm on the drawing. Figure 8As shown, airtightness test: seal the port M1 of the spinal tube, test the airtightness test pressure at the air inlet Q1, and test the welds: A5, A6, A7, A8, A9, A10, A11; the pressure is 0.6MPa, and the pressure is maintained for 10 minutes, and there is no leakage. Assembly welding of smoke chamber components:

[0049] like Fig. 9 , 10 As shown, the smoke chamber assembly includes a smoke main pipe 52, a smoke main pipe flange I51, a smoke main pipe flange II53, a smoke branch pipe 54, and a smoke branch pipe flange 55. In the first step, the smoke main pipe flange I, the smoke main pipe flange II and the two ends of the smoke main pipe are assembled and welded by using a tool, which meets the tolerance requirement of the drawing size L3; after the weldment shrinks and sets due to heat, the smoke branch pipe 54 is assembled and welded, which meets the tolerance requirement of the drawing size L4; in the second step, the smoke branch pipe flange 55 and the smoke branch pipe 54 are assembled and welded by using a tool, which meets the tolerance requirement of the drawing size L5; then the test tube and the sealing screw nut 56 are assembled and welded; assembly requirements: the post-welding size tolerance of L3, L4, and L5 is ±1mm. The welding welds B1 and B2 between the flue gas main pipe and the flue gas main pipe flange I and the flue gas main pipe flange II will reduce the size of L3, so the assembly should be positioned according to the drawing L3+2mm; welding process: for welding the B1 and B2 welds, the "reverse degeneration" welding method needs to be adopted: the flanges of the two flue gas chamber components are tightened with bolts and then welded, so that the welding stresses on both sides are restrained from each other. The B3 weld is an asymmetric weld located on the perforated steel pipe. In order to reduce the welding stress, the B3 weld is in accordance with the minimum fillet weld size specified in the standard, that is, 0.7 wall thickness (0.7T). The flanges of the two flue gas chamber components are tightened with bolts and then welded, so that the welding stresses on both sides are restrained from each other; the welds between the flue gas main pipe and the flue gas branch pipe are in accordance with the minimum fillet weld size; finally, an airtightness test is performed, and there is no leakage under this set condition. Air tightness test: Seal the flue gas main flange I51, flue gas main flange II53, test pipe and nut 56; use the flue gas branch flange 55 as the test air inlet for pressure test, and test the welds: B1, B2, B3, B4, B5; the pressure is 0.6MPa, and maintain the pressure for 10 minutes, no leakage.

[0050] Assembly welding of air inlet pipe assembly 6:

[0051] like Fig.11 , 12As shown, first assemble the air inlet straight pipe I61, the air inlet elbow 62, and the air inlet straight pipe II63 into a bent pipe assembly and weld them; then use the tooling to assemble and weld the air inlet pipe flange I64, the air inlet pipe flange II65 and the bent pipe assembly. Assembly requirements: The post-weld dimensional tolerance of L6 and L7 is ±1mm. The center line and axial direction of the air inlet pipe flange I64 and the air inlet pipe flange II65 must be vertical. Airtightness test: Test welds: C1, C2, C3, C4; the pressure is 0.6MPa, and the pressure is maintained for 10 minutes, and there is no leakage. (Multiple air inlet pipe assemblies can be connected for pressure testing) Finished assembly of the heat exchanger:

[0052] like Fig.13 As shown, in the first step, the smoke chamber assembly 5 is inserted into the secondary fin tube 2 end of the internal fin tube assembly 4; in the second step, the smoke chamber assembly 5 is connected to the connecting flange 7, that is, the smoke main pipe flange II 53 and the flange hole 73 are fastened with bolts, nuts and gaskets; then the sealing gasket I8 is placed between the connecting flange 7 and the secondary fin tube flange 43, and the countersunk process hole 71 of the connecting flange 7 is fastened with the secondary fin tube flange 43 using countersunk screws;

[0053] The third step is to place the sealing gasket II9 between the air inlet pipe flange II65 and the outer side of the connecting flange 7 on the outer side of the connecting flange 7, and fasten it with bolts, nuts and gaskets.

[0054] Technical requirements: 1. The assembly flange connections of all components meet the sealing requirements; the secondary fin tube flange 43 and the flue gas main flange II 53 are connected to the connecting flange 7 on the same plane and share a gasket, that is, the outer diameter of the sealing gasket I8 conforms to the connecting flange 7; 2. Because of the above requirement that "the plane of the secondary fin tube flange 43 must be perpendicular to the axial direction of the fin tube assembly", the plane of the flue gas main flange II 53 connected to the secondary fin tube flange 43 must be perpendicular to the axial direction of the fin tube assembly, and the flue gas main pipe 52 and the flange axial direction of the flue gas chamber assembly must be coaxial with the fin tube assembly to ensure that the 3 ends of the primary fin tube group of the heat exchanger can be inserted into the industrial furnace radiation tube, and the circumferential gap in the radiation tube is uniform; this type of radiation tube burner is made of flue gas bipolar heat exchanger, and can be used normally if it meets the above comprehensive technical requirements.

[0055] Although the specific embodiments of the present invention are described and illustrated in detail above, it should be pointed out that various equivalent changes and modifications can be made to the above embodiments based on the concept of the present invention. As long as the functional effects produced do not exceed the spirit covered by the specification, they should all be within the protection scope of the present invention.

Claims

1. A method for preparing a flue gas bipolar heat exchanger for a radiant tube burner, characterized in that: The three assemblies of the internal fin tube assembly, the smoke chamber assembly, and the air inlet pipe assembly are assembled and welded separately, and each is tested for air tightness after welding. Then, the smoke chamber assembly is inserted into the internal fin tube assembly first; then the smoke chamber assembly is connected to the connecting flange, and the flange of the air inlet pipe assembly is connected to the outside of the connecting flange on the outside of the connecting flange to complete the assembly; The internal fin tube assembly includes a hot air tube, a primary fin tube, and a secondary fin tube, wherein the hot air tube is assembled and welded in sequence from a hot air straight tube, an elbow, and a spinal tube; a groove is processed at one end of the hot air straight tube for connection with one end of the elbow, and the other end of the hot air straight tube is perpendicular to the spinal tube port; the secondary fin tube includes a plurality of fin tube fittings, a secondary fin large diameter tube, a toothed sealing plate, and a secondary fin small diameter tube, which are assembled and welded in sequence to form an intubation tube, and the three parts are on the same axis, and the secondary fin small diameter tube is perpendicular to the toothed sealing plate, and the secondary fin large diameter tube is located at one end of the toothed sealing plate. The groove is processed to connect the plurality of fins. The pipe fittings are sequentially sleeved on the outer wall of the secondary finned small-diameter tube, and are assembled and welded. All parts have the same axis, and all welds are closed welds. The primary finned tube includes a plurality of finned tube fittings and a finned tube head. After the plurality of finned tube fittings are assembled with the finned tube head, welding is completed. All parts have the same axis, and all welds are closed welds. The hot air pipe is inserted into the perforated steel pipe II, assembled with the perforated steel pipe I, and then assembled with the secondary finned tube and the primary finned tube with a tooling and welded. The secondary finned tube flange is installed at the end of the secondary finned large-diameter tube. The ends of the perforated steel pipe I and the perforated steel pipe II are processed with grooves, and the arc of the opening is consistent with the arc of the horizontal insertion of the elbow. All parts have the same axis. The smoke chamber assembly comprises a smoke main pipe, a smoke main pipe flange I, a smoke main pipe flange II, a smoke branch pipe, and a smoke branch pipe flange. The smoke main pipe flange I, the smoke main pipe flange II and the two ends of the smoke main pipe are assembled and welded by using a tool; after the weldment shrinks and sets due to heat, the smoke branch pipe is assembled and welded; the smoke branch pipe flange is assembled and welded with the smoke branch pipe by using a tool; then the test pipe and the sealing screw nut are assembled and welded; the smoke main pipe and the smoke main pipe flange I, the smoke main pipe flange II are welded, and the flanges of the two smoke chamber assemblies are fastened and welded by bolts, so that the welding stresses on both sides are restrained from each other; the welds between the smoke main pipe and the smoke branch pipe are of the minimum fillet weld size; finally, an airtightness test is performed, and no leakage is found under the set conditions; The air inlet pipe assembly includes an air inlet straight pipe I, an air inlet elbow, and an air inlet straight pipe II. First, the air inlet straight pipe I, the air inlet elbow, and the air inlet straight pipe II are assembled and welded; then, the air inlet pipe flange I, the air inlet pipe flange II, and the ends of the air inlet straight pipe I and the air inlet straight pipe II are assembled and welded using tooling. The center lines and axes of the flanges must be vertical. Finally, an air tightness test is performed to ensure that there is no leakage under the set conditions.

2. The method for preparing a flue gas bipolar heat exchanger for a radiant tube burner according to claim 1, characterized in that: First, weld the weld between the perforated steel pipe I and the perforated steel pipe II, and weld from the lower perforation to the non-perforation direction, and the weld is symmetrical on both sides, so that the internal fin tube group is deformed in the opposite direction of the weld at the perforation; then weld the weld between the perforated steel pipe I and the first-level fin tube, and the weld between the perforated steel pipe II and the second-level fin tube. When the weld between the perforated steel pipe I and the perforated steel pipe II drops to room temperature, weld the weld at the perforation, and all welds are closed welds; after welding the internal fin tube assembly, first test the linear value, and calibrate the previous weld to meet the linear tolerance, then put it back into the tooling and the second-level fin tube flange for positioning and assembly welding. The plane of the second-level fin tube flange must be perpendicular and coaxial to the axial direction of the internal fin tube assembly; finally, perform an airtight test, and there is no leakage under the set conditions.

3. The method for preparing a flue gas bipolar heat exchanger for a radiant tube burner according to claim 1, characterized in that: The smoke chamber assembly is inserted into the secondary fin tube end of the internal fin tube assembly; then the sealing gasket is placed between the connecting flange and the secondary fin tube flange, and fastened with countersunk screws; the smoke chamber assembly is connected to the connecting flange; on the outside of the connecting flange, the sealing gasket is placed between the air inlet pipe flange and the outside of the connecting flange, and fastened with bolts, nuts and gaskets; the assembly flange connections of all components meet the sealing requirements.

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