Method for prolonging service life of RH furnace dip pipe

Abstract

The invention relates to the technical field of metallurgy, and particularly discloses a method for prolonging the service life of an RH furnace dip pipe, which comprises the following steps: S1, prefabricating the dip pipe through refractory bricks, liner steel and a pouring material, arranging a dip pipe flange at the top of the liner steel, building a refractory layer in the liner steel through the refractory bricks, the top of the fireproof layer protrudes out of the dip pipe flange to form a protruding part; s2, a refractory brick in a dip pipe flange on the circulating pipe is shortened, so that a butt joint groove matched with the protruding part of the dip pipe in size is formed in the circulating pipe; s3, a protruding part on the dip pipe is in butt joint with a butt joint groove in the circulating pipe, and then a dip pipe flange and a steel structure flange on the circulating pipe are welded and sealed; the refractory layer protrudes to form the protruding part, and the butt-joint groove is formed in the bottom of the circulating pipe, so that brick joints can be staggered with weld joints of the dip pipe flange and the steel structure flange, molten steel is effectively prevented from being directly contacted with the weld joints after being immersed into the brick joints, and the service life is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a method for improving the service life of an RH furnace immersion tube. Background Art

[0002] The service life of the immersion tube is a restrictive factor in the operation of the RH furnace vacuum chamber system. Improving the service life of the RH furnace vacuum chamber is a key indicator for each steel plant, which has a great impact on production plan fulfillment, cost control, and refining efficiency.

[0003] The RH furnace vacuum chamber system is mainly composed of the upper vacuum tank and the lower immersion tube. One set of vacuum tanks can be used with multiple sets of immersion tubes. The RH furnace immersion tube is a complete prefabricated part. The inner layer of the immersion tube is assembled with refractory bricks; the outer layer is gall steel, which is used to fix the refractory bricks. At the same time, the immersion tube and the circulation tube at the lower end of the vacuum tank are welded together through a steel structure flange. The steel structure flange on the circulation tube is often deformed due to repeated use. When the deformed steel structure flange is docked with the new immersion tube, the following problems will occur: Because the steel structure flange of the circulation pipe is deformed after repeated use, the gap between it and the immersion pipe flange is large, and the brick seam formed by the inner refractory bricks on the immersion pipe and the refractory bricks of the circulation pipe is facing the weld between the above-mentioned steel structure flange and the immersion pipe flange, resulting in the molten steel eroding the brick gaps in the middle and late stages of the use of the immersion pipe, penetrating into the outer weld and burning through the latter.

[0004] If the weld is not tight and there are pores, the pores will penetrate the internal refractory brick seams. Under the vacuum negative pressure condition of the RH furnace, it is easy to inhale air, causing the internal refractory bricks to accelerate oxidation and erosion, eventually forming perforations and reducing the service life of the immersion tube.

[0005] The position of the brick joint inside the existing immersion pipe is exactly at the position where the steel slag stays before the vacuum starts, which increases the erosion rate of the refractory brick joints of the immersion pipe, forms serious grooves in the refractory brick joints, and reduces the service life of the immersion pipe. Summary of the invention

[0006] In view of the deficiencies of the prior art, the present invention provides a method for increasing the service life of an RH furnace immersion tube.

[0007] A method for increasing the service life of an RH furnace immersion tube of the present invention comprises the following steps: S1: The impregnation tube is prefabricated by refractory bricks, steel and casting material. The prefabrication process is: firstly, steel is placed in the mold, then refractory bricks are laid inside the steel to form a refractory layer, and finally casting material is filled between the mold and the steel. A dip tube flange is provided on the top of the steel bar, a refractory layer is formed inside the steel bar by refractory bricks, and the top of the refractory layer protrudes from the dip tube flange to form a protrusion; S2: Improve the circulation pipe on the vacuum tank by shortening the refractory bricks inside the immersion pipe flange on the circulation pipe so that a butt joint groove of a size matching the protrusion of the immersion pipe is formed on the circulation pipe to ensure that the total height of the immersion pipe and the circulation pipe remains unchanged, thereby ensuring that the height of the molten steel in the vacuum tank remains unchanged; S3: Butt the protrusion on the immersion pipe with the butt groove on the circulation pipe, and then weld and seal the immersion pipe flange and the steel structure flange on the circulation pipe.

[0008] Furthermore, the refractory layer is respectively built into a bottom refractory ring, a middle refractory ring and a top refractory ring from top to bottom by refractory bricks.

[0009] Furthermore, the distance between the brick joint between the top refractory ring and the middle refractory ring and the bottom of the immersion pipe is greater than mm, so that the brick joint avoids the slag surface height before vacuuming.

[0010] Furthermore, the butt surface structure of the immersion pipe flange is welded with a high-strength container plate with a thickness of more than mm.

[0011] Furthermore, after the immersion pipe and the butt groove on the circulation pipe are butt-jointed, it is necessary to fill the connection gap between the protrusion and the immersion pipe flange with casting material and pound it with a vibrating rod to avoid the formation of a cavity.

[0012] Furthermore, the casting material is made of corundum spinel, and its composition is Al2O3≥75%, Al2O3+MgO≥94%.

[0013] Furthermore, the casting material needs to be baked on a low fire to dry after pouring, and then baked on a high fire until dry before use to slowly remove moisture.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention is based on the existing RH furnace vacuum chamber process layout. By making the refractory layer protrude to form a protrusion and opening a docking groove at the bottom of the circulation tube, the brick seams between the refractory bricks on the circulation tube and the refractory bricks on the immersion tube and the immersion tube flange and the steel structure flange weld seams can be offset, thereby effectively avoiding that molten steel directly contacts the weld seams after immersing in the brick seams, thereby improving the service life. In addition, due to the offset of the weld seams and the brick seams, it is also possible to avoid that the pores in the loose weld seams of the steel structure are connected to the inside of the immersion tube to cause air suction, thereby avoiding that the pore air suction accelerates the oxidation erosion of the refractory bricks.

[0015] The distance between the brick joint between the top refractory ring and the middle refractory ring and the bottom of the immersion pipe is greater than mm, which can effectively avoid the slag surface height before vacuuming and the brick joint to be overlapped, avoid the slag surface height from corroding the brick joint, and thus improve the service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 It is a schematic diagram of the front cross-section structure of the present invention.

[0017] In the figure: 1, vacuum tank; 2, circulation pipe; 201, steel structure flange; 202, docking groove; 3, immersion pipe; 301, refractory layer; 302, gall steel; 303, casting material; 304, protrusion; 305, immersion pipe flange. DETAILED DESCRIPTION

[0018] The following will disclose multiple embodiments of the present invention with drawings. For the purpose of clear description, many physical details will be described together in the following description. However, it should be understood that these physical details should not be used to limit the present invention. That is, in some embodiments of the present invention, these physical details are not necessary. In addition, for the purpose of simplifying the drawings, some conventional structures and components will be depicted in a simple schematic manner in the drawings.

[0019] In addition, in the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes, and do not specifically refer to the order or sequence, nor are they used to limit the present invention. They are only used to distinguish components or operations described with the same technical terms, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0020] See also Figure 1 A method for increasing the service life of an RH furnace immersion tube of the present invention comprises the following steps: S1: prefabricate the dip tube 3 by means of refractory bricks, steel 302 and casting material 303. The prefabrication process is: firstly place the steel 302 in the mold, then lay refractory bricks inside the steel 302 to form a refractory layer 301, the top of the refractory layer 301 protrudes from the dip tube flange 305 to form a protrusion 304, and finally fill the casting material 303 between the mold and the steel 302; The top of the steel 302 is provided with an immersion pipe flange 305; S2: The circulation pipe 2 on the vacuum tank 1 is improved by shortening the refractory bricks inside the immersion pipe flange 305 on the circulation pipe 2, so that a docking groove 202 whose size matches the protrusion 304 of the immersion pipe 3 is formed on the circulation pipe 2, so as to ensure that the total height of the immersion pipe 3 and the circulation pipe 2 remains unchanged, thereby ensuring that the height of the molten steel in the vacuum tank 1 remains unchanged; S3: docking the protrusion 304 on the immersion pipe 3 with the docking groove 202 on the circulation pipe 2, and then welding and sealing the immersion pipe flange 305 and the steel structure flange 201 on the circulation pipe 2; S3.1. After the immersion pipe 3 is docked with the docking groove 202 on the circulation pipe 2, it is necessary to fill the connection gap between the protrusion 304 and the immersion pipe flange 305 with casting material 303, and use a vibrating rod to pound it to avoid the formation of a cavity. After pouring, the casting material 303 needs to be baked dry over a low fire, and then baked dry over a high fire before use to slowly remove moisture.

[0021] Furthermore, the refractory layer 301 is respectively built into a bottom refractory ring, a middle refractory ring and a top refractory ring from top to bottom by refractory bricks. In the process of forming the protrusion 304 on the refractory layer 301, the height of the refractory layer 301 relative to the refractory layer 301 in the existing immersion tube 3 will change. Therefore, it is necessary to improve the size of the existing prefabricated refractory bricks. When the size of the refractory bricks is improved, it can effectively avoid the brick joint between the top refractory ring and the middle refractory ring in the prior art being located within the slag surface, thereby effectively reducing the erosion of the brick joint between the top refractory ring and the middle refractory ring. The specific improvement is that the distance between the brick joint between the top refractory ring and the middle refractory ring and the bottom of the immersion tube 3 is greater than 720 mm, so that the brick joint avoids the slag surface height before vacuuming.

[0022] Furthermore, the butt joint structure of the immersion pipe flange 305 is welded with a high-strength container plate having a thickness of more than 45 mm.

[0023] The casting material 303 is made of corundum spinel, and its composition is Al2O3≥75%, Al2O3+MgO≥94%.

[0024] When using the present invention: The present invention, under the existing RH furnace vacuum chamber process layout, makes the refractory layer 301 protrude to form a protrusion 304, and opens a docking groove 202 at the bottom of the circulation tube 2, so that the brick joints between the refractory bricks on the circulation tube 2 and the refractory bricks on the immersion tube 3 and the welds of the immersion tube flange 305 and the steel structure flange 201 can be misaligned, thereby effectively avoiding that the molten steel directly contacts the weld after it penetrates into the brick joints, thereby improving the service life. In addition, due to the misalignment of the weld and the brick joint, it is also possible to avoid the situation where the pores in the loose welds of the steel structure are connected to the inside of the immersion tube 3 and the suction occurs, thereby avoiding that the pore suction accelerates the oxidation erosion of the refractory bricks.

[0025] The above is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. A method for increasing the service life of an RH furnace immersion tube, characterized in that: The steps include: S1: prefabricate a dip tube (3) using refractory bricks, gall steel (302) and casting material (303), wherein the prefabrication process is as follows: firstly, placing the gall steel (302) in a mold, then laying refractory bricks inside the gall steel (302) to form a refractory layer (301), wherein the top of the refractory layer (301) protrudes from the dip tube flange (305) to form a protrusion (304), and finally, filling the casting material (303) between the mold and the gall steel (302); The top of the steel tube (302) is provided with an immersion pipe flange (305); S2: improving the circulation pipe (2) on the vacuum tank (1), wherein the improved method is to shorten the refractory bricks inside the immersion pipe flange (305) on the circulation pipe (2), so that a docking groove (202) whose size matches the protrusion (304) of the immersion pipe (3) is formed on the circulation pipe (2), thereby ensuring that the total height of the immersion pipe (3) and the circulation pipe (2) remains unchanged; S3: docking the protrusion (304) on the immersion pipe (3) with the docking groove (202) on the circulation pipe (2), and then welding and sealing the immersion pipe flange (305) and the steel structure flange (201) on the circulation pipe (2).

2. A method for increasing the service life of an RH furnace immersion tube according to claim 1, characterized in that: The refractory layer (301) is respectively formed into a bottom refractory ring, a middle refractory ring and a top refractory ring from top to bottom by refractory bricks.

3. A method for increasing the service life of an RH furnace immersion tube according to claim 2, characterized in that: The distance between the brick joint between the top refractory ring and the middle refractory ring and the bottom of the immersion pipe (3) is greater than 720 mm, so that the brick joint avoids the height of the slag surface before vacuuming.

4. A method for increasing the service life of an RH furnace immersion tube according to claim 1, characterized in that: The butt joint structure of the immersion pipe flange (305) is welded with a high-strength container plate with a thickness of more than 45 mm.

5. A method for increasing the service life of an RH furnace immersion tube according to claim 1, characterized in that: S3.

1. After the immersion pipe (3) and the butt joint groove (202) on the circulation pipe (2) are butt jointed, it is necessary to fill the connection gap between the protrusion (304) and the steel structure flange (201) with casting material (303) and use a vibrating rod to pound it to avoid the formation of a cavity.

6. A method for increasing the service life of an RH furnace immersion tube according to claim 1 or 5, characterized in that: The casting material (303) is made of corundum spinel, and its composition is Al2O3≥75%, Al2O3+MgO≥94%.

7. A method for increasing the service life of an RH furnace immersion tube according to claim 1 or 5, characterized in that: The casting material (303) needs to be baked on a low fire to dry after casting, and baked on a high fire again to dry before use, and the moisture is slowly removed.

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