Cracking furnace tube welding apparatus and method

Abstract

The application discloses a kind of pyrolysis furnace tube welding devices, including machine base;Two furnace pipe chuck, for fixed butt joint and rotate two furnace pipes, are set on machine base;Welder, centrally arranged on machine base can be moved and weld the joint of two furnace pipes to form weld;Heater is provided on the machine base: it is arranged between two furnace pipe chuck, for step-by-step cooling weld;The heater includes two heating pipe sleeves symmetrically arranged on the machine base, and the heating pipe sleeve is coaxially arranged with the furnace pipe chuck, and a plurality of heating fins are provided in the heating pipe sleeve.The application forms a plurality of heat zones by adopting heater partition heating furnace pipe wall, which produces temperature difference along the welding rotation direction of furnace pipe, and makes weld pool pass through the plurality of heat zones with decreasing temperature in turn, so that the weld can be controlled to cool step by step during the welding process of furnace pipe, to prevent the generation of welding cracks caused by too fast cooling speed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of welding, in particular to a cracking furnace tube welding device and method. BACKGROUND

[0002] The furnace tube is an important component of the tubular furnace, for example, the furnace tube of the tubular cracking furnace, the inside of which carries out the hydrocarbon cracking reaction, and needs to be heated to a high temperature. The furnace tube is usually composed of a plurality of metal pipes welded together. Since it is in a high-temperature and sealed environment for a long time, the weld of the furnace tube welding position needs to be extremely firm, that is, the welding position of the furnace tube cannot have a slight crack.

[0003] The existing furnace tube welding device cannot control the cooling speed of the weld, and the molten pool of the weld exists the condition of too fast cooling, which causes the low-melting-point eutectic in the molten pool to segregate in the center of the weld. When the edge of the weld crystallizes and solidifies, the impurities between the grains in the center of the weld are still in the liquid film state, and under the action of the stress generated by the shrinkage of the weld, a slight crack is generated.

[0004] Therefore, during the furnace tube welding process, the too fast cooling speed of the weld easily causes welding cracks and affects the weld strength of the welding. The existing welding device cannot control the cooling speed of the weld during the welding process. SUMMARY

[0005] The purpose of the present application is to provide a cracking furnace tube welding device and method to solve the technical problem that the cooling speed of the weld cannot be controlled during the welding process in the prior art, which causes the too fast cooling speed of the weld to generate welding cracks.

[0006] To solve the above technical problems, the present application specifically provides the following technical solutions:

[0007] A cracking furnace tube welding device, comprising a base;

[0008] Two furnace tube chucks are arranged on the base for fixing and rotating two furnace tubes in abutment;

[0009] A welding machine is centrally arranged on the base and can move to weld the connection of the two furnace tubes to form a weld. The base is provided with:

[0010] A heater is arranged between the two furnace tube chucks for step-by-step cooling of the weld;

[0011] The heater comprises two heating pipe sleeves symmetrically arranged on the base, and the heating pipe sleeves are coaxially arranged with the furnace tube chucks. A plurality of heating fins are arranged in the heating pipe sleeves;

[0012] The distance between the plurality of heating pieces and the weld is gradually increased along the rotation direction of the furnace tube, or the temperature of the plurality of heating pieces is gradually decreased along the rotation direction of the furnace tube, or the distance between the plurality of heating pieces and the weld is gradually increased along the rotation direction of the furnace tube and the temperature of the plurality of heating pieces is gradually decreased along the rotation direction of the furnace tube, so as to preheat before welding and gradually reduce the cooling inhibition of the heating pipe sleeve at the weld during welding, so as to slowly cool the weld and prevent welding cracks.

[0013] As a preferred scheme of the present application, the plurality of heating pieces are arranged circumferentially along the inner wall of the heating pipe sleeve, and the distance between the plurality of heating pieces and the weld is gradually increased.

[0014] The temperature of the plurality of heating pieces is the same, so as to change the heat conduction distance between the heating area of the heating piece and the weld, and gradually cool the weld.

[0015] As a preferred scheme of the present application, the plurality of heating pieces are arranged circumferentially along the inner wall of the heating pipe sleeve, and the distance between the plurality of heating pieces and the weld is constant.

[0016] The temperature of the plurality of heating pieces is gradually decreased along the rotation direction of the furnace tube, so as to change the temperature difference between the heating area of the heating piece and the weld, and gradually cool the weld.

[0017] As a preferred scheme of the present application, the plurality of heating pieces are arranged circumferentially along the inner wall of the heating pipe sleeve, and the distance between the plurality of heating pieces and the weld is gradually increased.

[0018] The temperature of the plurality of heating pieces is gradually decreased along the rotation direction of the furnace tube, so as to change the temperature difference and the heat conduction distance between the heating area of the heating piece and the weld, and gradually cool the weld.

[0019] As a preferred scheme of the present application, the arc length of the plurality of heating pieces is gradually decreased along the rotation direction of the furnace tube, so as to gradually change the heat conduction time, and gradually cool the weld.

[0020] As a preferred scheme of the present application, a plurality of circumferentially distributed heat insulation plates are arranged on the inner wall of the heating pipe sleeve, and a heat insulation jacket for fixing the heating piece is arranged between adjacent two heat insulation plates on the inner wall of the heating pipe sleeve.

[0021] The height of the heat insulation plate is greater than the thickness of the heating piece, and the distance between adjacent two heat insulation plates matches the arc length of the heating piece.

[0022] As a preferred scheme of the present application, the circumferential distribution inner diameter of the plurality of heat insulation plates is greater than the outer diameter of the furnace tube to cover the end of the furnace tube, and a notch is formed on the top of each of the two heating pipe sleeves on the side close to the weld to cooperate to form a welding opening.

[0023] The axial length of the welding opening formed by the cooperation of the two notches is greater than the circumferential length thereof.

[0024] As a preferred scheme of the present application, the two heating pipe sleeves are connected to each other in contact or are not in contact with each other to adapt to different welds.

[0025] As a preferred scheme of the present application, each of the heating fins is provided with a power supply end, and a wiring end is arranged on the side wall of the heating pipe sleeve to connect the power supply end of the heating fin and a power supply module of the machine body.

[0026] The heater comprises a mounting rack mounted on a machine base, a connecting plug is arranged on the outer side wall of the heating pipe sleeve, and a connecting slot matched with the connecting plug is arranged on the mounting rack to realize quick disassembly and assembly of the heating pipe sleeve and the mounting rack.

[0027] To solve the above technical problems, the present application further provides the following technical scheme:

[0028] A welding method for furnace tubes of a cracking furnace, which adopts the welding device and comprises the following steps:

[0029] A, chamfering of a welding end; chamfering of the ends of the two furnace tubes to be welded;

[0030] B, rotary welding; after the two furnace tubes are clamped by the two furnace tube chucks and the chamfers of the two furnace tubes are butted, the two furnace tubes are synchronously and slowly rotated, and the welding machine is moved to the chamfer connection position of the two furnace tubes to perform welding;

[0031] C, gradual cooling; before welding, the heater is heated to preheat the two furnace tubes and maintain a temperature difference between the two furnace tubes and the weld to avoid welding cracks;

[0032] During welding, the weld sequentially passes through a high-temperature zone to a low-temperature zone of the weld formed by the heater with the rotation of the furnace tube, so that the temperature of the weld gradually decreases to realize gradual cooling to prevent welding cracks.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] The present application forms multiple heat zones with temperature difference along the welding rotation direction of the furnace tube by adopting the heater partition heating furnace tube wall, and makes the weld pool pass through the multiple heat zones with decreasing temperature in sequence, so that the weld can be controlled to cool gradually, and the welding crack caused by too fast cooling speed can be prevented. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only exemplary, and other drawings can be obtained by the provided drawings without creative labor for those skilled in the art.

[0036] Figure 1 The structure schematic diagram of the furnace tube welding device of the cracking furnace is provided for the embodiments of the present application.

[0037] Figure 2 The heater part structure schematic diagram of the furnace tube welding device of the cracking furnace is provided for the embodiments of the present application.

[0038] Figure 3 The heating sheet part structure schematic diagram of the furnace tube welding device of the cracking furnace is provided for the embodiments of the present application.

[0039] Figure 4 The heating pipe sleeve part structure schematic diagram of the furnace tube welding device of the cracking furnace is provided for the embodiment one of the present application.

[0040] Figure 5 The heating pipe sleeve part structure schematic diagram of the furnace tube welding device of the cracking furnace is provided for the embodiment two of the present application.

[0041] Figure 6 The heating pipe sleeve part structure schematic diagram of the furnace tube welding device of the cracking furnace is provided for the embodiment three of the present application.

[0042] The numbers in the drawings respectively represent as follows:

[0043] 1 - base; 2 - furnace tube chuck; 3 - welding machine; 4 - heater;

[0044] 41 - heating pipe sleeve; 42 - heating sheet; 43 - mounting frame; 44 - wiring end;

[0045] 411 - heat insulation clamp sleeve; 412 - heat insulation plate; 413 - notch; 414 - connecting plug; 421 - power supply end; 431 - connecting slot. DETAILED DESCRIPTION

[0046] Clearly and completely, the technical solutions in the embodiments of the present application will be described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0047] The present application provides a kind of pyrolysis furnace tube welding device, as shown in Figure 1 And Figure 2 It includes base 1;

[0048] Two furnace pipe chuck 2, be set on base 1 for fixed butt joint and rotate two furnace pipes;

[0049] Welding machine 3, centrally arranged on base 1 can be moved and welds the joint of two furnace pipes to form weld;It is provided with on base 1:

[0050] Heater 4, it is arranged between two furnace pipe chuck 2, for gradually cooling weld;

[0051] Heater 4 includes two heating pipe sleeves 41 symmetrically arranged on base 1, and heating pipe sleeve 41 is coaxially arranged with furnace pipe chuck 2, and a plurality of heating fins 42 are arranged in heating pipe sleeve 41;

[0052] Wherein, the distance between multiple heating fins 42 and weld gradually increases along the rotation direction of furnace pipe, or the temperature of multiple heating fins 42 gradually decreases along the rotation direction of furnace pipe, or the distance between multiple heating fins 42 and weld gradually increases along the rotation direction of furnace pipe and the temperature of multiple heating fins 42 gradually decreases along the rotation direction of furnace pipe, to preheat before welding and gradually reduce the cooling inhibition of heating pipe sleeve 41 at weld, so that weld slowly cools, to prevent welding crack.

[0053] The present embodiment mainly utilizes the heat generated by heater 4 at the welding weld of two furnace pipes, and changes the temperature difference between weld and furnace pipe by changing the distance between heat source and weld or changing the heat of heat source or changing the distance between heat source and weld and the heat of heat source, to realize the gradual slow cooling of weld.

[0054] Wherein, heating fin 42 can only locally heat furnace pipe wall without contact, since furnace pipe is metal material, then furnace pipe heat conduction and heat dissipation speed is fast, single heating fin 42 can only realize heating to small part area, then multiple heating fins 42 heat multiple furnace pipe wall areas, to form relatively uniform heat decreasing area along the rotation direction of furnace pipe, so that weld can slowly and gradually cool down.

[0055] Wherein, heating fin 42 adopts high-temperature resistant electric heating material, for example, silicon nitride ceramic electromagnetic sheet, etc., which has fast temperature rising speed, small volume, and can heat furnace pipe wall in small range.

[0056] The arrangement of multiple heating elements 42 within the heating sleeve 41 can be categorized into three types: multiple heating elements 42 with the same temperature but different distances from the weld; multiple heating elements 42 with different temperatures but the same distance from the weld; and multiple heating elements 42 with different temperatures and different distances from the weld. The following provides a detailed explanation of these three types:

[0057] Example 1 (Multiple heating elements 42 have the same temperature but different distances from the weld):

[0058] like Figure 4 As shown, multiple heating elements 42 are arranged circumferentially along the inner wall of the heating sleeve 41, and the distance between the multiple heating elements 42 and the weld increases in stages.

[0059] In this process, multiple heating elements 42 are at the same temperature, so that the weld can be cooled in stages by changing the heat conduction distance between the heating area of ​​the heating element 42 and the weld.

[0060] The heating element 42 heats the furnace tube wall. Since the multiple heating elements 42 have the same temperature, but their distance from the weld is different, the area of ​​the furnace tube wall heated by the heating element 42 that is far away from the weld is also far away from the weld. Therefore, some heat is transferred to the furnace tube wall near the weld, and some heat is lost.

[0061] Among them, the heating area of ​​the first heating element 42 near the weld seam generates a first hot zone a on the furnace tube wall near the weld seam. Part of the heat in the first hot zone a is conducted along the rotation direction of the furnace tube. Then, part of the heat in the heating area of ​​the second heating element 42 is conducted horizontally and merges with the heat conducted along the rotation direction of the furnace tube in the heating area of ​​the first heating element 42 to form a second hot zone b at the weld seam. Obviously, the temperature of the second hot zone b is lower than the temperature of the first hot zone a. Similarly, the temperature of the hot zone formed by the merging of multiple heating elements 42 at the weld seam gradually decreases, that is, a temperature difference is generated along the rotation direction of the furnace tube.

[0062] In this process, if any part of the weld passes through the first hot zone a during the rotation of the furnace tube, there will be a temperature difference between the two. If the weld temperature drops to a temperature no lower than that of the first hot zone a, then when it passes through the second hot zone b, the weld temperature will drop again to a temperature no lower than that of the second hot zone b. In this way, the weld temperature is gradually reduced to avoid rapid temperature drop that could cause welding cracks.

[0063] Example 2 (multiple heating elements 42 with different temperatures but the same distance from the weld):

[0064] like Figure 5 As shown, multiple heating elements 42 are arranged circumferentially along the inner wall of the heating sleeve 41, and the distance between the multiple heating elements 42 and the weld remains unchanged.

[0065] The temperature of multiple heating elements 42 decreases gradually along the rotation direction of the furnace tube, so as to cool the weld gradually by changing the temperature difference between the heating area of ​​the heating element 42 and the weld.

[0066] The heating element 42 heats the furnace tube wall. Since the temperature of the multiple heating elements 42 is different and the multiple heating elements 42 are close to the weld, the heating elements 42 heat the furnace tube wall near the weld to form multiple heating zones.

[0067] Among them, the first heating element 42 with the highest temperature heats the furnace tube wall to form the first hot zone a, and part of its heat is conducted towards the direction of furnace tube rotation. The second heating element 42 heats the furnace tube wall on the basis of the conduction and diffusion in the first hot zone a to form the second hot zone b. Obviously, the temperature of the second hot zone b is lower than the temperature of the first hot zone a. Similarly, the temperature of the hot zone formed by multiple heating elements 42 on the furnace tube wall at the weld gradually decreases, that is, a temperature difference is generated along the direction of furnace tube rotation.

[0068] In this process, if any part of the weld passes through the first hot zone a during the rotation of the furnace tube, there will be a temperature difference between the two. If the weld temperature drops to a temperature no lower than that of the first hot zone a, then when it passes through the second hot zone b, the weld temperature will drop again to a temperature no lower than that of the second hot zone b. In this way, the weld temperature is gradually reduced to avoid rapid temperature drop that could cause welding cracks.

[0069] Example 3 (multiple heating elements 42 with different temperatures and different distances from the weld):

[0070] like Figure 6 As shown, multiple heating elements 42 are arranged circumferentially along the inner wall of the heating sleeve 41, and the distance between the multiple heating elements 42 and the weld increases in stages.

[0071] The temperature of multiple heating elements 42 decreases gradually along the rotation direction of the furnace tube, thereby cooling the weld step by step by changing the temperature difference and heat conduction distance between the heating area of ​​the heating element 42 and the weld.

[0072] Heating elements 42 heat the furnace tube wall. Since the temperatures of multiple heating elements 42 are different and the distances between them and the weld are different, the area of ​​the furnace tube wall heated by the heating elements 42 that are far from the weld is also far from the weld. The heating area of ​​the first heating element 42 that is close to the weld generates a first hot zone a on the furnace tube wall near the weld. Part of the heat in the first hot zone a is conducted along the rotation direction of the furnace tube. Part of the heat in the heating area of ​​the second heating element 42 is conducted horizontally and merges with the heat conducted along the rotation direction of the furnace tube in the heating area of ​​the first heating element 42 at the weld to form a second hot zone b.

[0073] Since the temperature of the second heating sheet 42 is lower than that of the first heating sheet 42, and the distance between the second heating sheet 42 and the weld is greater than the distance between the first heating sheet 42 and the weld, it is obvious that the temperature of the second thermal zone b is lower than that of the first thermal zone a, and similarly, the temperatures of the thermal zones formed by the plurality of heating sheets 42 at the weld gradually decrease, that is, a temperature difference is generated along the rotation direction of the furnace tube.

[0074] Wherein, at any position of the weld during the rotation of the furnace tube, the weld passes through the first thermal zone a, and a temperature difference exists between the two, the temperature of the weld decreases to not less than the temperature of the first thermal zone a, and then the weld passes through the second thermal zone b, the temperature of the weld decreases again to not less than the temperature of the second thermal zone b. In this way, the weld is gradually cooled, and the temperature is not suddenly reduced to avoid weld cracking.

[0075] Compared with the three:

[0076] In the first embodiment, by controlling the temperature of the heating sheet 42 to be consistent, changing the distance between the heating sheet 42 and the weld, a plurality of thermal zones with a temperature difference along the rotation direction of the furnace tube are formed on the wall of the furnace tube at the weld, so that the temperature of the weld gradually decreases when passing through the plurality of thermal zones, thereby avoiding the weld from cracking due to sudden cooling.

[0077] Wherein, the plurality of heating sheets 42 have the same temperature, resulting in a relatively high total heat generation, but the power supply design is convenient, and the same current can be provided, while the plurality of heating sheets 42 gradually move away from the weld, resulting in a large heat loss and a high energy consumption.

[0078] In the second embodiment, by controlling the distance between the heating sheet 42 and the weld to be consistent, changing the temperature of the heating sheet 42, a plurality of thermal zones with a temperature difference along the rotation direction of the furnace tube are formed on the wall of the furnace tube at the weld, so that the temperature of the weld gradually decreases when passing through the plurality of thermal zones, thereby avoiding the weld from cracking due to sudden cooling.

[0079] Wherein, the plurality of heating sheets 42 need to provide different currents to control the heat, but the total heat generation of the plurality of heating sheets 42 is relatively low, and the plurality of heating sheets 42 are relatively concentrated at the weld, resulting in a small heat loss and an overall energy consumption.

[0080] In the third embodiment, by changing the distance between the heating sheet 42 and the weld and the temperature of the heating sheet 42, a plurality of thermal zones with a temperature difference along the rotation direction of the furnace tube are formed on the wall of the furnace tube at the weld, so that the temperature of the weld gradually decreases when passing through the plurality of thermal zones, thereby avoiding the weld from cracking due to sudden cooling.

[0081] Wherein, the plurality of heating sheets 42 need to provide different currents to control the heat, but the total heat generation of the plurality of heating sheets 42 is relatively low, while the plurality of heating sheets 42 gradually move away from the weld, resulting in a large heat loss and a general energy consumption.

[0082] Since the essence of metal heat conduction is the directional shuttle of free electrons, and as the temperature of the metal rises, the thermal motion of electrons and lattice in the metal intensifies, making the free electron shuttle motion blocked, therefore, the higher the temperature of the metal, the slower the cooling speed, therefore, the design of the heating sheet 42 is as follows:

[0083] As shown in Figure 2 , the arc length of the plurality of heating sheets 42 gradually decreases along the rotation direction of the furnace pipe, so as to gradually change the heat conduction time by stages, so that the weld is slowly cooled by stages.

[0084] Therefore, the arc length of the plurality of heating sheets 42 gradually decreases to adapt to the cooling speed of the weld, which avoids that the arc length of the heating sheet 42 is too long to cause the weld to still not leave the corresponding heat zone after the weld is cooled to the temperature of the corresponding heat zone in the corresponding temperature range, resulting in a decrease in the overall cooling speed, and also avoids that the arc length of the heating sheet 42 is too short to cause the weld to leave the corresponding heat zone and directly enter the next heat zone with a lower temperature before the weld is cooled to the temperature of the corresponding heat zone in the corresponding temperature range, resulting in a too large temperature difference between the two and a too fast cooling speed, thereby causing welding cracks.

[0085] Therefore, the arc length of the plurality of heating sheets 42 gradually decreases to adapt to the cooling speed of the weld, which avoids that the arc length of the heating sheet 42 is too long to cause the weld to still not leave the corresponding heat zone after the weld is cooled to the temperature of the corresponding heat zone in the corresponding temperature range, resulting in a decrease in the overall cooling speed, and also avoids that the arc length of the heating sheet 42 is too short to cause the weld to leave the corresponding heat zone and directly enter the next heat zone with a lower temperature before the weld is cooled to the temperature of the corresponding heat zone in the corresponding temperature range, resulting in a too large temperature difference between the two and a too fast cooling speed, thereby causing welding cracks.

[0086] The plurality of heating sheets 42 are arranged in the heating pipe sleeve 41, and the heat generated by the plurality of heating sheets 42 can interfere with each other, therefore, the heating sheet 42 needs to be isolated to avoid mutual influence. Details are described below:

[0087] As shown in Figure 2 , a plurality of heat insulation plates 412 are arranged on the inner wall of the heating pipe sleeve 41 in a circumferential direction, and a heat insulation sleeve 411 for fixing the heating sheet 42 is arranged between the adjacent two heat insulation plates 412 on the inner wall of the heating pipe sleeve 41.

[0088] The height of the heat insulation plate 412 is greater than the thickness of the heating sheet 42, and the distance between the adjacent two heat insulation plates 412 matches the arc length of the heating sheet 42.

[0089] The heating sheet 42 between each adjacent two heat insulation plates 412 is fixed at both ends by two heat insulation sleeves 411, so that the adjacent two heat insulation plates 412 can avoid the side end of the heating sheet 42 to heat outwardly to affect the adjacent heating sheet 42, and the two heat insulation sleeves 411 can also avoid the heat of the two ends of the heating sheet 42 to spread outwardly to cause heat loss.

[0090] The height of the heat insulation plate 412 is greater than the thickness of the heating sheet 42, so that the heat generated by the heating sheet 42 is limited to spread by the heat insulation plate 412, and the heat can be directly heated to the wall of the furnace tube, thereby improving the heating efficiency and reducing the heat loss.

[0091] As shown in Figure 2 , the circumferential distribution inner diameter of the plurality of heat insulation plates 412 is greater than the outer diameter of the furnace tube to cover the end of the furnace tube, and the top of the two heating pipe sleeves 41 on the side close to the weld is provided with a notch 413 to cooperate to form a welding port;

[0092] The axial length of the two notches 413 cooperating to form the welding port is greater than the circumferential length.

[0093] The heat insulation plate 412 can be inserted into the pipe wall of the furnace tube in the heating pipe sleeve 41 to minimize the heat loss of the heating sheet 42. The heating pipe sleeve 41 is provided with a notch 413 to adapt to the welding machine 3 for welding. When the welding machine 3 welds the furnace tube, it needs to reciprocate along the axis to improve the welding strength, so the axial length of the welding port formed by the two notches 413 needs to be greater than the swing amplitude, and the axial length is designed to be as short as possible to reduce the heat loss.

[0094] When the furnace tube is welded, there are different welding methods, such as flat welding, concave welding and convex welding. Different heating pipe sleeves 41 are provided for different welding methods to reduce heat loss and energy consumption. The following will be described in detail:

[0095] As shown in Figure 1 and Figure 2 , the two heating pipe sleeves 41 are in contact with each other or not in contact with each other between the two heating pipe sleeves 41 to adapt to different welds.

[0096] Among them, for flat welding and concave welding, the weld surface does not protrude from the furnace tube wall, so the two heating pipe sleeves 41 can adopt the mode of mutual contact connection to block part of the welding area, avoid heat overflow, reduce heat loss, and avoid the weld temperature being in contact with flowing air for too long to increase the cooling speed.

[0097] Among them, for convex welding, the weld surface protrudes from the furnace tube wall, so the two heating pipe sleeves 41 adopt the mode of mutual separation and non-contact, and a gap is formed between the two heating pipe sleeves 41 for the protruding weld to pass through. The inner diameter of the heating pipe sleeve 41 is not required to be confirmed according to the diameter of the convex welding, so that the heating pipe sleeve 41 can be more closely attached to the furnace tube wall and the heat loss is reduced as much as possible.

[0098] Different furnace tubes have different diameters. When welding, the furnace tube chuck 2 can freely adjust the clamping diameter, and the heating pipe sleeve 41 needs to be replaced to match the corresponding tube diameter of the furnace tube. The replacement of the heating pipe sleeve 41 requires disassembly and assembly operations. The following will explain in detail the disassembly and replacement of the heating pipe sleeve 41 to adapt to furnace tubes of different diameters:

[0099] As shown in Figure 2 and Figure 3 Each heating sheet 42 is provided with a power supply end 421, and a wiring end 44 is arranged on the side wall of the heating pipe sleeve 41 to connect the power supply end 421 of the heating sheet 42 and the power supply module of the machine body 1.

[0100] The heater 4 includes a mounting bracket 43 mounted on the machine base 1, and a connection plug 414 is arranged on the outer side wall of the heating pipe sleeve 41, and a connection slot 431 matched with the connection plug 43 is arranged on the mounting bracket 43, so as to realize the quick disassembly and assembly of the heating pipe sleeve 41 and the mounting bracket 43.

[0101] The power supply line on the power supply module of the machine body 1 is connected to the wiring end 44, so as to pass current to the power supply end 421 of the heating sheet 42 to generate heat, wherein the current of the power supply line is controlled by the power supply module of the machine body 1.

[0102] When replacing the heating pipe sleeve 41, first stop the machine and disconnect the power supply line, then pull out the connection plug 414 from the connection slot 431, then replace the corresponding heating pipe sleeve 41, then connect the power supply line to the wiring end 44 and start the machine. The operation is simple and the disassembly and assembly are convenient.

[0103] Based on the above welding device, a furnace tube welding method of a cracking furnace is provided, which includes the following steps:

[0104] A, chamfering of the welding end; chamfering the ends of the two furnace tubes to be welded;

[0105] B, rotary welding; after the two furnace tube chucks 2 drive the chamfers of the two furnace tubes to butt joint, they are synchronously and slowly rotated, and the welding machine is moved to the chamfer connection of the two furnace tubes for welding;

[0106] C, step-by-step cooling; before welding, the heater is warmed up to preheat the two furnace tubes and maintain the temperature difference between the welds to avoid welding cracks;

[0107] Wherein, the heating of the heater 4 is the heating of the plurality of heating sheets 42 in the heating pipe sleeve 41, and after the heating sheets 42 are warmed up, they heat the furnace tube wall to form a plurality of heat zones rotating along the furnace tube direction to generate a temperature difference. The plurality of heat zones can preheat the furnace tube and step-by-step cool the welds;

[0108] In the welding, the weld is rotated with the furnace tube to sequentially pass through the high-temperature zone to the low-temperature zone formed by the heater on the weld, so that the temperature of the weld gradually decreases, and gradual cooling is realized to prevent welding cracks.

[0109] Wherein, the weld is rotated with the furnace tube to sequentially pass through the multiple heat zones with gradually decreasing temperature after the weld is formed, so that the heat of any part of the weld will gradually decrease, avoiding the weld from being cooled too fast to produce welding cracks.

[0110] The above examples are only exemplary embodiments of the present application, and are not used to limit the present application, and the protection scope of the present application is defined by the claims. Those skilled in the art can make various modifications or equivalent replacements to the present application within the spirit and protection scope of the present application, and such modifications or equivalent replacements are also regarded as falling within the protection scope of the present application.

Claims

1. A welding device for pyrolysis furnace tubes, comprising a base (1); Two furnace tube chucks (2) are set on the machine base (1) for fixing and rotating the two furnace tubes; The welding machine (3) is centrally mounted on the base (1) and can move to weld the connection between two furnace tubes to form a weld; its characteristic is that... The base (1) is provided with: A heater (4) is disposed between the two furnace tube chucks (2) to progressively suppress the cooling rate of the weld. The heater (4) includes two heating tube sleeves (41) symmetrically arranged on the base (1), and the heating tube sleeves (41) are coaxially arranged with the furnace tube chuck (2). Multiple heating elements (42) are arranged inside the heating tube sleeves (41). The distance between the multiple heating elements (42) and the weld increases gradually along the direction of furnace tube rotation, or the temperature of the multiple heating elements (42) decreases gradually along the direction of furnace tube rotation, or the distance between the multiple heating elements (42) and the weld increases gradually along the direction of furnace tube rotation and the temperature decreases gradually along the direction of furnace tube rotation, so as to reduce the cooling suppression of the weld by the heating sleeve (41) before welding and during welding, so that the weld cools slowly and prevents welding cracks from occurring. Multiple heating elements (42) are arranged circumferentially along the inner wall of the heating tube sleeve (41), and the distance between the multiple heating elements (42) and the weld increases gradually along the rotation direction of the furnace tube; The temperature of the multiple heating elements (42) decreases gradually along the rotation direction of the furnace tube, so as to cool the weld gradually by changing the temperature difference and heat conduction distance between the heating area of ​​the heating element (42) and the weld. The arc length of the plurality of heating elements (42) gradually decreases along the rotation direction of the furnace tube, so as to gradually cool the weld by changing the heat conduction time step by step. Multiple circumferentially distributed heat insulation plates (412) are provided on the inner wall of the heating tube sleeve (41), and heat insulation jackets (411) for fixing the heating element (42) are provided between two adjacent heat insulation plates (412) on the inner wall of the heating tube sleeve (41). The height of the heat insulation plate (412) is greater than the thickness of the heating element (42), and the distance between two adjacent heat insulation plates (412) matches the arc length of the heating element (42).

2. The pyrolysis furnace tube welding device according to claim 1, characterized in that, The inner diameter of the multiple heat insulation plates (412) is larger than the outer diameter of the furnace tube to cover the end of the furnace tube. Notches (413) are provided on the top of the two heating tube sleeves (41) on the side near the weld to form a weld joint. The axial length of the weld joint formed by the two notches (413) is greater than its circumferential length.

3. The pyrolysis furnace tube welding device according to claim 1, characterized in that, The two heating sleeves (41) are either in contact with each other or not in contact, to accommodate different weld seams.

4. The pyrolysis furnace tube welding device according to claim 1, characterized in that, Each of the heating elements (42) is provided with a power supply terminal (421), and a wiring terminal (44) is provided on the side wall of the heating tube sleeve (41) to connect the power supply terminal (421) of the heating element (42) and the power module of the base (1); The heater (4) includes a mounting bracket (43) mounted on the base (1), a connecting plug (414) is provided on the outer wall of the heating tube sleeve (41), and a connecting slot (431) that mates with the connecting plug (414) is provided on the mounting bracket (43) to enable quick assembly and disassembly of the heating tube sleeve (41) and the mounting bracket (43).

5. A method for welding furnace tubes in a pyrolysis furnace, characterized in that, The welding apparatus according to any one of claims 1-4 comprises the following steps: A. Beveling and grinding the ends of the welded ends; beveling and grinding the ends of the two furnace tubes to be welded; B. Rotary welding: After the two furnace tube chucks drive the bevels of the two furnace tubes to be joined, they rotate slowly and synchronously. The welding machine moves to the bevel connection of the two furnace tubes to perform welding. C. Step-by-step cooling; Before welding, the heater preheats the two furnace tubes and maintains a temperature difference with the weld to avoid welding cracks. During welding, the weld seam rotates with the furnace tube and passes sequentially through the high-temperature zone to the low-temperature zone formed by the heater, so that the temperature of the weld seam decreases step by step, achieving gradual cooling to prevent welding cracks from forming.

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