Process method for replacing furnace shell of blast furnace

Abstract

The invention relates to the technical field of blast furnace metallurgical equipment, in particular to a process method for replacing a blast furnace shell. The invention provides a process method for replacing a furnace shell of a blast furnace, which comprises the following steps of: dismantling the furnace shell, dismantling the furnace shell to be dismantled and a cooling wall, and arranging fixed lifting lugs at the periphery of the dismantling range of the blast furnace; hoisting the furnace shell, setting a corner part, welded with the blast furnace, on the replaced furnace shell to be in arc transition, and putting the replaced furnace shell on a tuyere platform chute by using a hoisting mechanism and pulling the replaced furnace shell to a to-be-mounted position; and the furnace shell is installed, inner openings are aligned during installation of the replaced furnace shell, the alignment tolerance of the openings is smaller than or equal to 6 mm, and the replaced furnace shell is adjusted to enable the center distance of adjacent group holes of the cooling wall to be + / -3 mm. And furnace shell welding is conducted, CO2 gas shielded welding is adopted for welding, multi-layer and multi-pass welding and symmetrical welding are conducted on the replaced furnace shell and the blast furnace, and pre-welding preheating and post-welding slow cooling are conducted on welding vertical seams and circular seams. By implementing the technical scheme disclosed by the invention, a new furnace shell is convenient to replace, and the problem of cracking caused by stress concentration of a welding seam of the furnace shell is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of blast furnace metallurgical equipment, and in particular to a process method for replacing a blast furnace shell. Background Art

[0002] The existing blast furnace has been in operation for a long time, and is equipped with multiple cooling walls. After long-term use, many cooling walls and water pipes have been damaged and leaking, and the number and scope of damage have been increasing month by month, which has seriously affected the normal production of the blast furnace; after the cooling wall is damaged, the blast furnace shell will directly contact the red-hot charge, and then the furnace shell will turn red, the mechanical properties will decrease, and in more serious cases, the furnace shell will burn through. Therefore, if the furnace shell is found to be red during the production process, it must be cooled by external water sprinkling cooling to protect the furnace shell from further deterioration. Otherwise, the temperature difference between the inside and outside of the furnace shell is huge, the thermal stress of the furnace shell changes dramatically, and cracks are easily generated from the opening of the cooling equipment. When the crack penetrates from the inside to the outside, a large amount of dusty high-temperature coal gas will leak, and then the deterioration of the furnace shell will be accelerated.

[0003] How to ensure safe operation after furnace shell replacement through reasonable welding technology has become a difficult problem that needs to be solved urgently. Summary of the invention

[0004] The present disclosure aims to solve at least one of the technical problems existing in the prior art or related art.

[0005] To this end, the present disclosure provides a process for replacing a blast furnace shell, comprising:

[0006] Model positioning, designing a furnace skin mold according to a preset shape, wherein the circumferential edge of the furnace skin mold is provided with a plurality of arc-shaped connecting surfaces;

[0007] Removing the furnace shell, using the corresponding position of the furnace shell mold shape on the blast furnace to remove the furnace shell and cooling wall to be removed, and setting fixed lifting lugs around the removal range of the blast furnace;

[0008] Furnace shell hoisting: using the furnace shell mold to make a replacement furnace shell, and using a hoisting mechanism to place the replacement furnace shell on the tuyere platform chute and pull it to the dismantling range of the blast furnace;

[0009] The furnace shell is installed. The replacement furnace shell is installed with the inner edge aligned, and the misalignment is ≤6mm. The replacement furnace shell is adjusted so that the center distance between adjacent groups of holes on the cooling wall is ±3mm.

[0010] The furnace shell is welded by CO2 gas shielded welding. The furnace shell and the blast furnace are welded by multi-layer and multi-pass welding and symmetrical welding. The vertical seams and circumferential seams are preheated before welding and slowly cooled after welding.

[0011] In a feasible implementation manner, a marking line welding and cutting shape model is set at the position of the furnace shell to be removed, and the shape model is used to cut the furnace shell to be replaced.

[0012] In a feasible embodiment, at least two connecting ears are arranged on the replacement furnace shell, the number of the fixed ears is the same as the number of the connecting ears, and when the replacement furnace shell corresponds to the dismantling range of the blast furnace, the connecting ears and the fixed ears are arranged relative to each other.

[0013] In a feasible implementation, when the replacement furnace shell is set for internal and external welding, grooves are opened circumferentially on the inside and outside of the replacement furnace shell at the same time; when the replacement furnace shell is set for external welding, "K"-shaped grooves are opened at the connection parts between the replacement furnace shell and the old furnace shell of the blast furnace.

[0014] In a feasible implementation manner, in the furnace shell welding step, a pneumatic pick is used to remove welding slag after each welding.

[0015] In a feasible implementation manner, the preheating temperature of the preheating furnace shell before welding is set to 400° C. to 450° C., and the preheating time is set to 1 to 2 hours.

[0016] In a feasible implementation manner, in the welding step, the welding is completed and the furnace is heated again with a flame, and when the furnace shell temperature reaches 280° C. to 320° C., the furnace is naturally cooled slowly for 8 to 10 hours under insulation conditions.

[0017] In a feasible implementation manner, the vertical seam welding and the circumferential seam welding are performed continuously, and the welding sequence is to perform the vertical seam welding first and then the circumferential seam welding.

[0018] In a feasible implementation manner, the welding wire for the CO2 gas shielded welding is set to be a THY-51B flux-cored welding wire, and the diameter of the flux-cored welding wire is set to Φ1.2 mm.

[0019] In a feasible implementation manner, the welding sequence for replacing the furnace shell is set to start from the center point of one edge of the demolition range of the blast furnace, and weld sequentially along the circumference of the demolition range of the blast furnace.

[0020] The above description is only an overview of the technical solution provided by the present disclosure. In order to more clearly understand the technical means of the present disclosure, it can be implemented according to the contents of the specification. In order to make the above and other features and effects of the present disclosure more obvious and easy to understand, the implementation methods of the present disclosure are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0022] 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, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0023] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the exemplary embodiments below. The accompanying drawings are only for the purpose of illustrating exemplary embodiments and are not to be considered as limiting the present application. Also, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0024] Figure 1 A schematic diagram of the process flow of the present disclosure;

[0025] Figure 2 It is a schematic diagram of the welding direction sequence of multiple furnace shells disclosed in the present invention.

[0026] in, Figure 1 and Figure 2 The corresponding relationship between the reference numerals and the component names is: 100-temporary platform; 200-angle iron; 1-replacement of furnace shell; 2-arc-shaped connecting surface. DETAILED DESCRIPTION

[0027] In order to more clearly understand the above-mentioned objectives, features and advantages of the present disclosure, the scheme of the present disclosure will be further described below. It should be noted that the embodiments of the present disclosure and the features in the embodiments can be combined with each other without conflict.

[0028] In the following description, many specific details are set forth to facilitate a full understanding of the present disclosure, but the present disclosure may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0029] At present, the existing blast furnaces have been in operation for a long time, and multiple cooling walls are set on the blast furnaces. After long-term use, many cooling walls and multiple water pipes are damaged and leaking, and the number and scope of damage are increasing month by month, which has seriously affected the normal production of the blast furnace; after the cooling wall is damaged, the blast furnace skin will directly contact the red-hot charge, and then the furnace shell will turn red, the mechanical properties will decrease, and in more serious cases, the furnace skin will burn through. Therefore, if the furnace skin is found to be red during the production process, it must be cooled by external water sprinkling cooling to protect the furnace skin from further deterioration. Otherwise, the temperature difference between the inside and outside of the furnace skin is huge, and the thermal stress of the furnace skin changes dramatically, which is easy to produce cracks from the opening of the cooling equipment. When the crack penetrates from the inside to the outside, a large amount of dusty high-temperature coal gas will leak, and then accelerate the deterioration of the furnace skin. How to ensure the safe operation after the furnace skin is replaced through a reasonable welding process has become a problem that needs to be solved urgently.

[0030] Based on this, the disclosed embodiment provides a process method for replacing a blast furnace cladding, including cladding removal, removing the cladding to be removed and the cooling wall, and setting fixed lifting lugs around the removal range of the blast furnace; cladding hoisting, setting the corner portion of the replacement cladding welded to the blast furnace as an arc transition, using a hoisting mechanism to place the replacement cladding on the tuyere platform chute and pull it to the installation location; cladding installation, the replacement cladding is aligned with the inner mouth during installation, the misalignment of the mouth is ≤6mm, and the replacement cladding is adjusted so that the center distance between adjacent groups of holes in the cooling wall is ±3mm. The cladding is welded by CO2 gas shielded welding, and the replacement cladding and the blast furnace are welded by multi-layer and multi-pass welding and symmetrical welding, and the vertical seams and circumferential seams are preheated before welding and slowly cooled after welding.

[0031] The process for replacing the blast furnace shell is described in detail below by means of specific embodiments:

[0032] Reference Figures 1 to 2 As shown, the present disclosure provides a process for replacing a blast furnace shell, comprising:

[0033] Model positioning, designing the furnace skin mold according to the preset shape, and setting multiple arc-shaped connecting surfaces on the circumferential edge of the furnace skin mold;

[0034] Removing the furnace shell, using the furnace shell mold at the corresponding position on the blast furnace to remove the furnace shell and cooling wall to be removed, and setting fixed lifting lugs around the removal range of the blast furnace;

[0035] The furnace shell is hoisted, and the corner 2 part of the replacement furnace shell 1 welded with the blast furnace is set to an arc transition, and the replacement furnace shell 1 is placed on the tuyere platform chute using a hoisting mechanism and pulled to the place to be installed;

[0036] When installing the furnace skin, replace the furnace skin 1 and align it with the inner edge, with the misalignment of the edges ≤6mm, and adjust the replacement furnace skin 1 so that the center distance between adjacent groups of holes on the cooling wall is ±3mm;

[0037] The furnace shell is welded by CO2 gas shielded welding. By replacing the furnace shell 1 and the blast furnace, multi-layer and multi-pass welding is adopted and the welding is performed symmetrically. The vertical seams and circumferential seams are preheated before welding and slowly cooled after welding.

[0038] The furnace skin mold disclosed in the present invention has multiple identical arc-shaped connecting surfaces 2, and the size of the arc-shaped connecting surfaces 2 is determined by the specific space on site, and is opened as large as possible if conditions permit; the size of the furnace skin 1 to be replaced is preferably two cooling walls, which is convenient for hoisting, cutting and welding operations. Specifically, the furnace skin mold is set to a square or rectangular shape, and the number of the arc-shaped connecting surfaces 2 is set to four, and the arc-shaped connecting surfaces 2 are respectively set at the four corner points of the furnace skin mold. The arc-shaped connecting surfaces 2 can effectively reduce the stress concentration when replacing the old furnace skin with the new one.

[0039] The furnace skin cutting mold disclosed in the present invention can be cut from a thin iron plate, and the inside and outside are welded to the furnace skin to be removed. When cutting the furnace skin, an oxygen melting rod is used to cut the furnace skin along the inner circle of the furnace skin mold to ensure the accuracy of the cutting shape. The thickness of the blast furnace skin is generally 60 to 80 mm, and its rigidity is relatively large. It will produce a lot of stress during the welding process, and there is a defect of cracking. In order to prevent cracks and reduce welding stress, both the vertical seam and the circumferential seam must be preheated before welding and slowly cooled after welding. The preheating is heated by gas baking. During baking, two gas pipes are used for each weld, with the position of 50 to 80 mm on both sides of the weld as the center of the flame, and the flame angle is 45 degrees.

[0040] Specifically, the replacement of the furnace shell 1 is welded by multiple welders using carbon dioxide gas shielded welding at the same time, using flux-cored wire model THY-51B, and the diameter of the wire is 1.2mm. In the first embodiment of the present disclosure, both internal and external double-sided welding is adopted. For the parts with large welds, steel bars are first attached to the outside. After the internal welding is completed, each welder welds one quarter of the furnace shell 5 to 6 times, and then the slag inclusions are removed from the outside by air planing and then welded. Before welding, a temporary platform should be set up and covered with asbestos cloth to prevent the lower welder from being scalded. During the welding process, the position of the weld joint should be avoided to be set on the range of the four arc-shaped connecting surfaces 2 to ensure the continuity of the weld of the arc-shaped connecting surface 2 and avoid cracking caused by stress; and multi-layer and multi-pass welding should avoid one layer being too wide. The thicker the weld, the greater the heat input and the coarser the grains of the structure. When welding vertical seams and circumferential seams, interruption of welding should be avoided, and welding should not be stopped without reason in the middle. In special circumstances, corresponding protective measures (reheating) must be adopted. The welding current of carbon dioxide gas shielded welding is shown in the following table:

[0041] CO2 gas shielded welding

[0042]

[0043] After replacing the furnace shell 1 and welding, heat it again with flame. When it reaches about 300℃, measure the temperature with a temperature gun. The heating time is 2-3 hours. Protect the outside with refractory fiber felt to allow it to cool naturally under heat preservation conditions. Check the temperature every hour and keep records. Ultrasonic flaw detection is used for flaw detection according to the grade II weld specified in "GB / T11345-1989", and 100% of the weld length is tested.

[0044] In some embodiments, at least two connecting ears are set on the replacement furnace shell 1, wherein the number of fixed ears is the same as the number of connecting ears. When the replacement furnace shell corresponds to the dismantling range of the blast furnace, the connecting ears and the fixed ears are arranged relative to each other to facilitate the fixing of the position of the replacement furnace shell 1.

[0045] In some embodiments, when the furnace shell 1 is replaced and set to be welded inside and outside, grooves are opened in the circumferential direction of the inner and outer parts of the furnace shell 1; when the furnace shell 1 is replaced and set to be welded outside, "K"-shaped grooves are opened at the connection parts between the furnace shell 1 and the old furnace shell of the blast furnace. The grooves of the furnace shell 1 are quickly cut by air planing. The furnace shell 1 with internal and external welding adopts the form of internal and external grooves, and the new and old furnace shells without internal and external welding have K-shaped grooves. K-shaped groove refers to the shape of the weld on both sides of the welding joint, which is K-shaped, usually composed of the oblique welds on both sides and the transverse weld at the bottom. : The oblique welds and transverse welds of the K-shaped groove are tightly combined, which can provide higher welding strength and ensure the firmness and good sealing of the welding joint. The shape of the K-shaped groove can effectively improve the sealing of the welding joint and avoid liquid or gas leakage. And the penetration depth is well controlled. The design of the K-shaped groove helps to control the penetration depth during welding, thereby improving the quality of the weld. Compared with the V-shaped groove, the K-shaped groove can reduce the amount of weld metal, and can be welded symmetrically, and the residual deformation after welding is small.

[0046] In this embodiment, during the furnace shell welding step, the welding slag is removed with a pneumatic pick after each welding to eliminate stress.

[0047] In some embodiments, the preheating temperature of the preheating furnace shell before welding is set to 400° C. to 450° C., and the preheating time is set to 1 to 2 hours. After the preheating starts, the heating speed should not be too fast, and the total preheating time is required to be completed within 1 to 2 hours.

[0048] In some embodiments, in the welding step, the furnace is heated again with a flame after welding, and when the furnace shell temperature reaches 280°C to 320°C, it is naturally cooled slowly for 8 to 10 hours under insulation conditions, thereby reducing the occurrence of welding cracks.

[0049] In some embodiments, the vertical seam welding and the circumferential seam welding are performed continuously, and the welding sequence is first the vertical seam welding and then the circumferential seam welding. After the longitudinal seam welding is completed, the basic shape is fixed, which helps the accuracy and stability of the subsequent circumferential seam welding.

[0050] In some embodiments, the welding wire for CO2 (carbon dioxide) gas shielded welding is set to THY-51B flux-cored welding wire, and the diameter of the flux-cored welding wire is set to Φ1.2mm. Flux-cored welding wire is also called powder-cored welding wire or tubular welding wire. It is divided into two categories: gas-entrained welding wire and non-gas-entrained welding wire. The present disclosure specifically uses gas-entrained welding wire. The surface of the flux-cored welding wire is the same as that of the solid welding wire, and is made of materials such as low-carbon steel or low-alloy steel with good plasticity.

[0051] The HY-51B welding wire selected in the present disclosure has small spatter during welding and a stable and soft arc, which makes the welding process smoother and reduces interference and difficulty during welding. Since the arc is stable and soft, the weld is beautiful, which is very beneficial for applications that require high-quality welding surfaces.

[0052] In some embodiments, Figure 2 As shown, welding is performed in the order of the outer peripheries of the four parts A, B, C, and D in the figure. The welding sequence for replacing the furnace shell is set to start from the center point of one edge of the demolition range of the blast furnace, and welding is performed in circumferential order along the demolition range of the blast furnace.

[0053] In the present disclosure, the terms "first", "second", and "third" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance; the term "plurality" refers to two or more, unless otherwise expressly defined. The terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to the specific circumstances.

[0054] In the description of the present disclosure, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "left", "right", "front", "back", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, rather than indicating or implying that the device or unit referred to must have a specific direction, be constructed and operated in a specific orientation, and therefore, should not be understood as a limitation on the present disclosure.

[0055] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0056] The above are only preferred embodiments of the present disclosure and are not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A process for replacing a blast furnace shell, characterized in that: include: Model positioning, designing a furnace skin mold according to a preset shape, wherein the circumferential edge of the furnace skin mold is provided with a plurality of arc-shaped connecting surfaces; Removing the furnace shell, using the corresponding position of the furnace shell mold shape on the blast furnace to remove the furnace shell and cooling wall to be removed, and setting fixed lifting lugs around the removal range of the blast furnace; Furnace shell hoisting: using the furnace shell mold to make a replacement furnace shell, and using a hoisting mechanism to place the replacement furnace shell on the tuyere platform chute and pull it to the dismantling range of the blast furnace; Installation of furnace skin: the replacement furnace skin should be aligned with the inner edge during installation, with the misalignment of the edges ≤6mm, and the replacement furnace skin should be adjusted so that the center distance between adjacent groups of holes on the cooling wall is ±3mm; The furnace shell is welded by CO2 gas shielded welding. The furnace shell and the blast furnace are welded by multi-layer and multi-pass welding and symmetrical welding. The vertical seams and circumferential seams are preheated before welding and slowly cooled after welding.

2. A process for replacing a blast furnace shell according to claim 1, characterized in that: A marking line welding and cutting shape model is set at the position of the furnace shell to be removed, and the shape model is used to cut the furnace shell to be replaced.

3. The process for replacing the blast furnace shell according to claim 1, characterized in that: At least two connecting lugs are arranged on the replacement furnace shell, the number of the fixed lugs is the same as the number of the connecting lugs, and when the replacement furnace shell corresponds to the dismantling range of the blast furnace, the connecting lugs and the fixed lugs are arranged opposite to each other.

4. The process for replacing the blast furnace shell according to claim 1 is characterized in that: When the replacement furnace shell is set to be internal and external welding, grooves are opened circumferentially on the inside and outside of the replacement furnace shell; when the replacement furnace shell is set to be external welding, "K"-shaped grooves are opened at the connection parts between the replacement furnace shell and the old furnace shell of the blast furnace.

5. The process for replacing the blast furnace shell according to claim 1, characterized in that: In the step of welding the furnace shell, a pneumatic pick is used to remove welding slag after each welding.

6. The process for replacing the blast furnace shell according to claim 1, characterized in that: The preheating temperature of the preheating furnace shell before welding is set to 400° C. to 450° C., and the preheating time is set to 1 to 2 hours.

7. The process for replacing the blast furnace shell according to claim 1, characterized in that: In the welding step, the furnace is heated again with a flame after welding, and when the furnace shell temperature reaches 280° C. to 320° C., it is naturally cooled slowly for 8 to 10 hours under insulation conditions.

8. The process for replacing the blast furnace shell according to claim 1, characterized in that: The vertical seam welding and the circumferential seam welding are performed continuously, and the welding sequence is to perform the vertical seam welding first and then the circumferential seam welding.

9. The process for replacing the blast furnace shell according to claim 1, characterized in that: The welding wire for the CO2 gas shielded welding is set to be THY-51B flux-cored welding wire, and the diameter of the flux-cored welding wire is set to Φ1.2mm.

10. The process for replacing the blast furnace shell according to claim 1, characterized in that: The welding sequence of replacing the furnace shell is set to start from the center point of one edge of the demolition range of the blast furnace, and weld in sequence along the circumference of the demolition range of the blast furnace.

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