Welding method for partial replacement of furnace shell of smelting blast furnace

Abstract

The invention relates to the field of blast furnace shell installation, maintenance and replacement, and discloses a welding method for partial replacement of a smelting blast furnace shell, to-be-replaced furnace shell sections are m furnace shell sections in the middle of a blast furnace, and n groups of furnace shell areas, sequentially arranged in the circumferential direction, of the m furnace shell sections are sequentially replaced. The welding method comprises the following steps that a first group of furnace shell areas are replaced, a new furnace shell and an old furnace shell are fixedly connected through a clamping plate, and then transverse seams between adjacent zones of the new furnace shell and between the new furnace shell and the old furnace shell are fixedly connected in a welding mode; and sequentially replacing the (2-n) th group of furnace shell areas, firstly connecting and fixing vertical seams between the new furnace shells in a welding manner, and then connecting and fixing transverse seams between adjacent zones of the new furnace shells and between the new furnace shells and the old furnace shells in a welding manner. By means of the welding method, the purpose that the stress and deformation of the weld joint after welding are within the minimum range can be achieved.

Description

Technical Field

[0001] The invention relates to the field of installation, maintenance and replacement of blast furnace shells, and in particular to a welding method for partial replacement of a smelting blast furnace shell. Background Art

[0002] As a metallurgical ironmaking production equipment that continuously reduces iron-containing raw materials into pig iron under high temperature and high pressure, the interior of the blast furnace is in a high-temperature and high-pressure environment of gas, liquid and solid coupling under normal production conditions. The working conditions are extremely harsh, and the internal and external load conditions are very complex. The blast furnace shell is often burned through, and after the shell is partially burned through or cracked, the internal gas will quickly escape in large quantities through the gap in the shell in the form of hot air flow, causing serious fire, explosion and poisoning hazards. At this time, it is necessary to replace the shell and its internal cooling system at the burned-through and cracked parts. In addition, there is also a practical engineering demand for partial replacement of the shell during the overhaul and medium repair of the blast furnace.

[0003] In the past, furnace shell replacement was done from the furnace base to the furnace roof. The entire construction period took about 100 days, sometimes even longer. In addition, there were a large number of construction workers during the construction, and multi-layer operations and cross-operations were frequent, which increased the difficulty of safety risk control and the probability of safety accidents. In addition, a large number of constructions were carried out at the same time, which increased the amount of skilled operators involved in the construction. However, the number of highly skilled operators was limited, which easily led to the low skill level of many welders, and the quality of the welds was far from meeting the standards. At this time, it was easy to have shoddy work. The only way to improve the situation is to change the construction process to reduce the large-scale labor input and adopt small-scale construction to achieve a small but fine construction effect.

[0004] Therefore, how to economically and efficiently replace the partial shell of a smelting blast furnace while ensuring welding quality has become a technical problem that needs to be solved urgently in this field. Summary of the invention

[0005] The main purpose of the present invention is to provide a welding method for partial replacement of a smelting blast furnace shell, so as to achieve the purpose of keeping the stress and deformation of the weld after welding within the minimum range.

[0006] According to the present invention, a welding method for partial replacement of a furnace shell of a smelting blast furnace is provided, wherein the furnace shell segments to be replaced are m furnace shell segments in the middle part of the blast furnace, and n groups of furnace shell areas of the m furnace shell segments arranged in sequence along the circumferential direction are replaced in sequence, and the welding method comprises the following steps: replacing the first group of furnace shell areas, first using a clamping plate to fix the new furnace shell and the old furnace shell, and then using welding to connect and fix the transverse seams between adjacent bands of the new furnace shell and between the new furnace shell and the old furnace shell; replacing the second to n groups of furnace shell areas in sequence, first using a clamping plate to fix the new furnace shell and the old furnace shell, using welding to connect and fix the vertical seams between the new furnace shells, and then using welding to connect and fix the transverse seams between adjacent bands of the new furnace shell and between the new furnace shell and the old furnace shell.

[0007] According to one embodiment of the present invention, during the replacement of the first to nth groups of furnace shell regions, the welding of the transverse seams is performed in two stages. The first stage: welding of 1 / 2 of the furnace shell thickness is completed at each transverse seam in a welding sequence that meets a predetermined condition; the second stage: welding of the remaining 1 / 2 of the furnace shell thickness is completed at each transverse seam in the same welding sequence as the first stage. The predetermined condition is: welding two non-adjacent transverse seams in succession.

[0008] According to one embodiment of the present invention, the second stage of welding is performed after the weld obtained by the first stage of welding is cooled.

[0009] According to one embodiment of the present invention, during the replacement of the first group of furnace shell areas, during welding, 500 mm to 800 mm of transverse seams are reserved at both ends of the transverse welds and are not welded.

[0010] According to one embodiment of the present invention, during the replacement of the first group of furnace shell areas, each transverse weld is welded symmetrically from the middle to both ends by two people on the inside and two people on the outside.

[0011] According to one embodiment of the present invention, during the replacement of the 2nd to nth groups of furnace shell regions, two non-adjacent vertical seams are welded successively.

[0012] According to one embodiment of the present invention, during replacement of the 2nd to nth groups of furnace shell regions, the vertical seams are welded in sections, each weld section is 500 mm to 700 mm long, and the number of sections is determined according to the weld length.

[0013] According to one embodiment of the present invention, during replacement of the 2nd to nth groups of furnace shell regions, the transverse seams are welded in sections, and a 500mm to 800mm transverse seam is reserved between each group of transverse welds and the ends of the previous group of transverse welds without being welded.

[0014] According to one embodiment of the present invention, during the replacement of the 2nd to nth groups of furnace shell regions, the transverse seam is welded in 6 sections, and each section of the transverse weld is welded symmetrically by 3 people inside and outside at equal intervals simultaneously along the same direction.

[0015] According to one embodiment of the present invention, after welding is completed, the following operations are performed: welding deformation correction; weld quality inspection; and defective weld repair.

[0016] In the technical solution of the present invention, a partial non-unloading method is adopted to replace the furnace shell of the partial section of the furnace body by digging and patching. Different welding processes are used for the first group of furnace shells and the second to n groups of furnace shells, and the welding sequence is arranged in accordance with the principle of vertical first and then horizontal, short first and then long. The vertical welds of the first group of furnace shells connecting the new and old furnace shells are not welded and connected by fixtures. The horizontal welding of the first group is completed, and then the second group of furnace shells is removed. The vertical welding of the second group of furnace shells and the old furnace shell is still connected by fixtures. When the first group of furnace shells and the second group of furnace shells are welded, the vertical welding parts connected to the first group are welded first, and then the horizontal welding parts are welded. All welding is performed according to the pre-established welding process requirements to minimize welding stress and deformation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 A flow chart showing a welding method for partial replacement of a smelting blast furnace shell according to an embodiment of the present invention; Figure 2 A schematic diagram showing the location of the furnace shell replacement area on the upper elevation of the blast furnace; Figure 3 A schematic diagram of the expansion of the replacement area is shown; Figure 4 An expanded exterior view showing the replacement area; Figure 5 A schematic diagram showing the location of the furnace shell replacement area in a cross section of a blast furnace; Figure 6 A schematic diagram showing the main process of furnace shell replacement; Figure 7 A schematic diagram showing a first group of furnace shell welding sequence according to an embodiment of the present invention is shown; Figure 8 A schematic diagram of the welding sequence of the second group and the remaining groups of furnace shells according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0020] It should be understood that the embodiments of the present invention shown in the exemplary embodiments are only illustrative. Although only a few embodiments are described in detail in the present invention, it is easy for those skilled in the art to appreciate that multiple modifications are feasible without actually departing from the teaching of the subject matter of the present invention. Accordingly, all such modifications should be included within the scope of the present invention. Without departing from the gist of the present invention, other replacements, modifications, changes and deletions may be made to the design, operating conditions and parameters of the following exemplary embodiments.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field of the present invention; the terms used in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the directions or positions indicated by the terms "length", "width", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc. are based on the directions or positions shown in the drawings, which are only for the convenience of description and should not be understood as limitations on the present technical solution.

[0022] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0023] Figure 1 A flow chart of a welding method for partial replacement of a blast furnace shell according to an embodiment of the present invention is shown, wherein the shell segments to be replaced are m shell segments in the middle of the blast furnace, and n groups of shell regions of the m shell segments arranged in sequence along the circumferential direction are replaced in sequence. Figure 1 As shown, the welding method includes the following steps: Step S1, replacing the first group of furnace shell areas, first using a clamping plate to fix the new furnace shell and the old furnace shell, and then using welding to connect and fix the transverse seams between adjacent bands of the new furnace shell and between the new furnace shell and the old furnace shell; Step S2, replace the 2nd to nth groups of furnace shell areas in sequence, first use a clamp to fix the new furnace shell and the old furnace shell, use welding to fix the vertical seams between the new furnace shells, and then use welding to fix the transverse seams between adjacent bands of the new furnace shell and between the new furnace shell and the old furnace shell.

[0024] The present invention is mainly aimed at the welding process of replacing the entire furnace shell one by one by digging and patching when partially replacing and installing the furnace shell. The original construction of replacing the entire blast furnace body is changed to replacing the local high-temperature section, and a certain welding process is adopted to achieve the stress and deformation of the weld after welding within the minimum range. It can be applied to the partial replacement welding of all large furnace bodies and tank bodies. Compared with the overall replacement, the construction period is greatly shortened, and the labor cost and material cost are also greatly reduced year-on-year. It has a greater impact on the normal production cycle of the production party, and the production efficiency is greatly improved year-on-year, which can be said to kill two birds with one stone. In an embodiment of the present invention, the partial furnace shell is replaced in sequence by non-unloading and regional formation. The furnace shell segment to be replaced is m furnace shell segments in the middle part of the blast furnace. Non-unloading replacement specifically means that the load above the furnace shell segment does not need to be supported on the blast furnace frame for unloading before construction. The area-forming replacement is to divide the entire circumference of the furnace body of the furnace shell segment to be replaced into n groups, and each time the hole is opened 360 / n degrees, it is replaced in a clockwise direction along the circumference in a total of n groups, that is, the area-forming replacement method, first dismantle one area along the circumference, and then fill in another area in order until all the plates are replaced. This can avoid the collapse and displacement of the upper furnace body due to complete loss of support after all the old furnace shells are removed. Preferably, the connecting edges of adjacent furnace shell segments in the n groups of furnace shells are staggered with each other. For example, when the first group of furnace shells and the second group of furnace shells are installed, the vertical seam at the first furnace shell segment between the two is not aligned with the vertical seam at the second furnace shell segment, the vertical seam at the second furnace shell segment is not aligned with the vertical seam at the third furnace shell segment... The vertical seam at the m-1th furnace shell segment is not aligned with the vertical seam at the mth furnace shell segment.

[0025] During the replacement of the 1st to nth groups of furnace shell areas, the welding of the transverse seams is carried out in two stages. Specifically, in the first stage, the welding of 1 / 2 of the furnace shell thickness is completed at each transverse seam in a welding sequence that meets the predetermined conditions. The predetermined conditions can be set as: welding two non-adjacent transverse seams in succession. For example, the transverse seams at odd positions such as 1, 3, 5 can be welded first, and then the transverse seams at even positions such as 2, 4, 6 can be welded. After the welds obtained by the first stage of welding are cooled, the second stage of welding is performed. In the second stage: the welding of the remaining 1 / 2 of the furnace shell thickness is completed at each transverse seam in the same welding sequence as in the first stage.

[0026] In an embodiment of the present invention, during replacement of the first group of furnace shell areas, during welding, 500mm~800mm transverse seams are reserved at both ends of the transverse welds and are not welded. Each transverse weld can be welded symmetrically from the middle to both ends by two people on the inside and outside.

[0027] In an embodiment of the present invention, during the replacement of the 2nd to nth groups of furnace shell regions, the principle of vertical first and then horizontal, short first and then long is adhered to. That is, the vertical seams are welded first and then the horizontal seams; the short seams are welded first and then the long seams. In addition, the welding of the vertical seams must also meet the predetermined conditions for welding two non-adjacent vertical seams in succession. The vertical seams are welded in sections, and the length of each weld section is 500mm~700mm; the horizontal seams are also welded in sections, and each group of horizontal welds and the end of the previous group of horizontal welds reserve 500mm~800mm of horizontal seams that are not welded. In a preferred embodiment of the present invention, during the replacement of the 2nd to nth groups of furnace shell regions, the horizontal seams are welded in 6 sections, and each section of the horizontal weld is welded symmetrically in the same direction at the same time by 3 people inside and outside at equal intervals.

[0028] After welding is completed, the following operations can be performed: welding deformation correction; weld quality inspection; and repair of defective welds. Those skilled in the art can set the correction process and different levels of quality standards according to actual working conditions.

[0029] The following describes a specific embodiment as an example.

[0030] refer to Figures 2 to 4 Taking the shutdown and overhaul project of the new No. 3 blast furnace of a certain ironmaking plant as an example, the blast furnace is a self-supporting blast furnace with a furnace body height of 37.240m, which consists of the hearth, furnace belly, furnace waist, furnace body, furnace throat and other parts. The diameter of the furnace shell is distributed between 3.7 and 12.85m, and the maximum diameter is located at the furnace waist, with a diameter of 12.85m. The thickness of the furnace shell plate is between 36 and 65mm. The main engineering construction content is to replace the furnace shell within the range of 17.315m to 28.470m. The furnace shell within this range is divided into six belts arranged in sequence along the height direction, specifically the 6th to 11th belts, that is, the furnace waist section, 3 sections of the furnace body on the furnace waist, and 2 sections of the furnace belly below the furnace waist, a total of 6 sections.

[0031] In order to shorten the construction period to the maximum extent and ensure that all elevation dimensions after the furnace shell is replaced and the stress and deformation after the weld is within the minimum range, a local non-unloading method is used to replace the furnace shell in a local section of the furnace body. The furnace shell replacement process can include the following process: removal of the inlet and outlet openings → removal of the cooling wall → replacement of the furnace shell → completion of the furnace shell replacement → installation of a new cooling wall → restoration of the inlet and outlet openings.

[0032] Due to partial replacement, in order to prevent the dismantled one-sixth of the furnace shell from deflecting downward, to prevent or reduce the local deformation of the 12-band and 5-band furnace shells after the removal of the middle section of the blast furnace shell (6 to 12 cooling walls), and to prevent the center of the blast furnace shell from shifting, etc. Therefore, it is necessary to reinforce the old furnace body above the replacement section in the early stage, and then dismantle the cooling walls in the furnace and open the inlet and outlet holes. The inventors of this application recognize that compared with the traditional blast furnace overhaul and partial replacement of the furnace shell, the blast furnace segmented replacement scheme of this embodiment has the following characteristics: (1) Replacement without unloading: Due to the actual situation on site, this renovation project cannot support the load above the elevation of 28.470m (the constant load weight of the furnace shell, equipment, cooling wall, etc. within the 16.2m height range is about 1200t) on the blast furnace frame for renovation under unloading conditions.

[0033] (2) Area formation replacement: The entire circumference of the furnace body of the replaced section is divided into 6 groups. The specific construction sequence is as follows: Figure 5 As shown in the figure, according to the scheme of opening holes 60 degrees each time, the replacement is divided into 6 sections along the circumference clockwise, that is, the old furnace shell of an area along the circumference is first removed, the length*width is about 6.8m*12m, and then the new furnace shell of the area is added until all the plates are replaced. Among them, considering the staggered weld seams, the actual central angle of each hole is about 78 degrees. For specific reference Figure 6 ,in Figure 6 (a) shows the removal of the first set of furnace shells, Figure 6 (b) shows the installation of the first set of furnace shells, Figure 6 (c) shows the removal of the second set of furnace shells, Figure 6 (d) shows the installation of the second set of furnace shells, Figure 6 (e) shows that the third to sixth groups of furnace shells are continuously dismantled and installed until all the furnace shells are replaced. This can avoid the collapse and displacement of the upper furnace body due to complete loss of support after all the old furnace shells are removed.

[0034] (3) In order to prevent the overall sinking of the furnace shell above 12 zones, the furnace shell from 6 to 11 zones is divided into 6 groups for replacement in a whole circle, with 1 / 6 arc segments of the whole circle replaced each time. The next group of 1 / 6 arc segments can only be replaced after the first group of 1 / 6 arc segments are welded to form a whole.

[0035] In this embodiment, the qualification check of personnel before operation: all welding personnel must pass the examination and obtain a certificate of qualification. This welding adopts two welding methods: manual arc welding + CO2 gas shielded welding. The welding wire uses flux-cored welding wire corresponding to brand CHT711. The welding wire must have a factory quality certificate and comply with the corresponding national standards before it can be used. Among them: (1) Manual welding uses E5015 welding rods, which must be baked before use at a temperature of 300-350°C for 1-2 hours. They should be placed in a heat preservation barrel and taken out as needed. (2) The purity of the shielding gas for CO2 gas shielded welding must be ≥99.5% and the moisture content must be ≤0.005%; (3) Preheat before welding. Use a large baking gun to bake the area within 150mm on both sides of the weld. When the temperature reaches 100 to 150℃, weld again. (4) During welding, each layer of welding slag must be strictly cleaned and the weld quality must be checked to avoid defects such as slag inclusion and lack of fusion; (5) During welding, the interlayer temperature should be controlled not lower than the preheating temperature. After welding, asbestos should be used for insulation to reduce the cooling rate of the weld. (6) Use a pneumatic shovel to knock the interlayer weld during and after welding to eliminate welding stress; (7) Use stress detection instruments to conduct real-time detection of furnace body welds.

[0036] During welding, the root welding is done by manual arc welding on the inside. After the welding is done, if the back of the weld is well formed, a flat grinding wheel metal brush can be used to clean the root. When the weld gap is improper and the back is poorly formed, resulting in incomplete penetration, incomplete fusion, weld nodules and slag inclusions, carbon arc air planing is used to clean the root first, and then the planed oxide layer is cleaned with a grinder before normal welding. After completion, the outside is welded with a 3-4mm weld thickness in the same welding direction as the root welding sequence. After manual welding is completed, a flat grinding wheel metal brush is used to check the internal and external welds, and then carbon dioxide gas shielded welding is used for welding symmetrically at the same time. For internal and external symmetrical welding, a small line energy segmented back welding method is used for welding. The current value of the Φ1.2 flux core does not exceed 220A. When welding in segments, the connection needs to be staggered by about 30mm~50mm.

[0037] The welding sequence of the welding process in this embodiment is described below: Step S1, welding of the first furnace shell.

[0038] After the on-site installation is completed, the vertical welds on both sides of the furnace shell are connected to the old furnace shell, so the vertical welds on both sides are not welded. The new furnace shell is fixed by connecting the clamp plate to the old furnace shell, and only the transverse seams need to be welded. Figure 7 As shown, in order to reduce welding stress and deformation, during welding, 500mm~800mm of welds are reserved at both ends of the transverse weld and not welded. Two people from the inside and outside weld symmetrically from the middle of the transverse weld along arrows 1 and 2 towards both ends.

[0039] The sequence of welding one transverse seam and then welding another transverse seam is adopted. All welds are welded in two stages, such as Figure 7 As shown, in the first stage, transverse seams ②, ④, and ⑥ are welded to form a weld with a width of 1 / 2 of the furnace shell thickness, that is, two people facing each other inside and outside weld symmetrically from the center of the furnace shell thickness, so that the weld formed by the first stage welding occupies 1 / 2 of the furnace shell thickness; then, transverse seams ①, ③, and ⑤ are welded in the same way to form a weld with a width of 1 / 2 of the furnace shell thickness; finally, transverse seam ⑦ is welded in the same way to form a weld with a width of 1 / 2 of the furnace shell thickness. It is particularly emphasized that when the overall furnace shell temperature drops below 100 degrees Celsius, transverse seam ⑦ is welded. After the above welds are cooled, the second stage of welding is carried out. Two people facing each weld inside and outside weld symmetrically from the original weld, so that the weld formed by the second stage welding occupies the remaining 1 / 2 of the furnace shell thickness. The welding sequence of the second stage is the same as that of the first stage.

[0040] This welding sequence is mainly used to connect the six grouped welds to the lower section of the old furnace shell to form a whole, and not to weld the upper section welds of the old furnace shell first. In this way, the welding of the lower furnace shell will not be restricted by the upper old furnace shell, and the welding stress can be well released, thus avoiding large stress concentration in the weld.

[0041] Step S2, welding of the second group and the remaining groups.

[0042] Adhere to the principle of vertical first and horizontal later, short first and long later. Take the second group of furnace shell as an example. Figure 8 As shown, first weld the vertical seams (2), (4), and (6), and then weld the vertical seams (1), (3), and (5). The vertical welds can be welded in sections, and the length of each weld section is about 500mm~700mm to avoid excessive welding stress caused by the weld being too long. According to the specific length of the vertical weld, it is divided into 2 to 3 sections, and the welding is performed symmetrically inside and outside in a back-welding manner. For example, the vertical seam (1) at the 6th belt is shorter and can be divided into 2 sections for welding. First weld the 1st weld position and then weld the 2nd weld position in the direction indicated by the arrow; the vertical seam (3) at the 8th belt is longer and can be divided into 3 sections for welding. The welding sequence is still in the direction indicated by the 1, 2, and 3 arrows, and the welding is performed in a back-welding manner, in layers, and symmetrically inside and outside.

[0043] The second and remaining transverse welds can be evenly divided into 6 sections for welding, leaving 500~800mm between the ends of the next interface unwelded. Three people inside and outside weld in the direction indicated by the arrows in a back-welding manner, in layers, and symmetrically inside and outside. That is, first weld simultaneously as follows Figure 8 The thickness of the single side plate of the welding positions ①, ②, and ③ shown in the figure is half the thickness, and then welded at the same time as shown in the figure. Figure 8 The ④, ⑤, and ⑥ welding positions shown are half the thickness of the single-side plate; then the welds of the remaining plate thickness of the ①, ②, and ③ welding positions are welded to complete, and then the welds of the remaining plate thickness of the plate of the ④, ⑤, and ⑥ welding positions are welded to complete.

[0044] The second and remaining transverse welds can also be welded in the order of welding one transverse weld and then welding another transverse weld. All welds are welded in two stages. The specific order can refer to the welding order of the first group of furnace shell welding.

[0045] Among them, the welding parameters of the horizontal weld are shown in Table 1, and the welding parameters of the vertical weld are shown in Table 2: Table 1 Transverse weld welding parameters

[0046] Table 2 Vertical weld parameters

[0047] After welding is completed, do the following steps in sequence: (1) Welding deformation correction Flame is mainly used for correction in areas with large local deformation and excessive ovality.

[0048] (2) Check weld quality (2.1) Check whether the weld surface quality meets the following requirements: There shall be no defects such as cracks, weld bumps, pores, slag inclusions, arc crater cracks, arc scratches, etc. on the weld surface. Specifically: Inspection quantity: 10% of the length of each type of weld in each section shall be inspected; Inspection method: Inspection by observation or using a magnifying glass, weld gauge and steel ruler. If necessary, inspection by penetrant testing.

[0049] (2.2) Weld inspection The furnace shell welds are randomly inspected at a rate of 10%; the main inspection is at the "T" joints, and the ultrasonic inspection quality is level II; 100% ultrasonic testing must be performed at the cross-section change point; Any areas where there is doubt about the welding quality must be subjected to 100% ultrasonic testing; The length of each spot-checked part and the length of the T-shaped seam in each direction shall not be less than 300mm; (3) Repair defective welds, specific requirements: (3.1) According to the specific location, length and depth of the internal defects of the weld provided by the flaw detector, use a grinder or carbon arc gouging to clean the weld defects; the carbon rod should be a round carbon rod of Φ6~Φ8 according to the depth and width of the defect, and the pressure of the compressed air should be between 0.4Mpa~0.6Mpa; (3.2) When the operator touches the defective position, he is required to clean it slowly until it is clean. It is strictly forbidden to plane with large ups and downs; (3.3) Choose the length and the planing point of the defect according to the depth of the defect. Plane 10~15mm more at both ends of the defect and form a 45°~60° bevel angle with moderate upper and lower widths, striving to form a V-shaped angle to facilitate the next step of welding; (3.4) Use a polishing machine and a straight grinder to remove the carburized layer; (3.5) For shell-type steel structures, they should be preheated according to the actual temperature before re-welding. The preheating temperature is about 150°C, and the preheating length is 2 to 3 times longer than the repair length. The repaired welds should be welded with manual electrodes.

[0050] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as described above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A welding method for partial replacement of a blast furnace shell, characterized in that: The furnace shell segments to be replaced are m furnace shell segments in the middle part of the blast furnace, and n groups of furnace shell areas of the m furnace shell segments arranged in sequence along the circumferential direction are replaced in sequence. The welding method comprises the following steps: Replace the first group of furnace shell areas, first use a clamp to fix the new furnace shell and the old furnace shell, and then use welding to connect and fix the transverse seams between adjacent bands of the new furnace shell and between the new furnace shell and the old furnace shell; Replace the 2nd to nth groups of furnace shell areas in sequence, first use clamps to fix the new furnace shell and the old furnace shell, use welding to fix the vertical seams between the new furnace shells, and then use welding to fix the transverse seams between adjacent bands of the new furnace shells and between the new furnace shell and the old furnace shell.

2. The welding method according to claim 1, characterized in that: During the replacement of the 1st to nth group of furnace shell areas, the welding of the transverse seams is carried out in two stages: The first stage: complete the welding of 1 / 2 of the furnace shell thickness at each transverse seam in a welding sequence that meets the predetermined conditions; The second stage: complete the welding of the remaining 1 / 2 of the furnace shell thickness at each transverse seam in the same welding sequence as the first stage; Wherein, the predetermined condition is: welding two non-adjacent transverse seams successively.

3. The welding method according to claim 2, characterized in that: After the weld obtained by the first stage of welding is cooled, the second stage of welding is performed.

4. The welding method according to claim 2, characterized in that: During the replacement of the first group of furnace shell areas, during welding, 500mm~800mm transverse seams are reserved at both ends of the transverse weld without welding.

5. The welding method according to claim 4, characterized in that: During the replacement of the first group of furnace shell areas, each transverse weld is welded symmetrically from the middle to both ends by 2 people on the inside and outside.

6. The welding method according to claim 2, characterized in that: During replacement of the 2nd to nth groups of furnace shell areas, two non-adjacent vertical seams are welded successively.

7. The welding method according to claim 6, characterized in that: During the replacement of the 2nd to nth groups of furnace shell areas, the vertical seams are welded in sections, with each weld section being 500mm to 700mm long, and the number of sections is determined based on the weld length.

8. The welding method according to claim 7, characterized in that: During the replacement of the 2nd to nth groups of furnace shell areas, the transverse seams are welded in sections, and a 500mm to 800mm transverse seam is reserved between the ends of each group of transverse welds and the previous group of transverse welds without being welded.

9. The welding method according to claim 8, characterized in that: During the replacement of the 2nd to nth groups of furnace shell areas, the transverse seams are welded in 6 sections, and each section of the transverse weld is welded symmetrically in the same direction at the same time by 3 people inside and outside at equal intervals.

10. The welding method according to claim 1, characterized in that: After soldering is complete, do the following: Welding deformation correction; Check weld quality; Repair defective welds.

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