Masonry method of circulating pipe at bottom of vacuum tank

Abstract

The invention discloses a building method of circulating pipes at the bottom of a vacuum tank, which comprises the following steps: the circulating pipes are divided into an ascending circulating pipe group and a descending circulating pipe group which are positioned on two sides of the center of the tank bottom; the circulating pipe is formed by combining and building an upper layer of circulating pipe bricks and a lower layer of circulating pipe bricks, the upper layer of circulating pipe bricks are sequentially and alternately built at two heights, the lower layer of circulating pipe bricks are sequentially and alternately built at two heights, and the heights of the built circulating pipes are consistent; the tank bottom is formed by building lower-layer electric smelting recombined magnesia-chrome bricks and upper-layer direct combined magnesia-chrome bricks around circulating pipe bricks and filling gaps with recombined magnesia-chrome ramming materials; and after the tank bottom is built, a layer of electro-fused recombined magnesium-chromium tank wall bricks are vertically built above the circulating pipe bricks of the ascending circulating pipe group. According to the method, the erosion degree of molten steel to the circulating pipe is effectively reduced, the occurrence of groove penetrating accidents is reduced, the service life of the vacuum groove is prolonged, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgical devices, in particular to a masonry method for a vacuum tank bottom circulation pipe. Background Art

[0002] The short service life of RH vacuum tanks has an adverse impact on the release of RH production capacity and the reduction of ton steel cost. In-depth analysis of the causes of RH furnace refractory loss and taking corresponding measures to extend the service life of vacuum tanks are an important guarantee for accelerating capacity release and reducing production costs.

[0003] Handan Iron and Steel No. 1 Steelmaking Plant currently has a 120t double-station RH furnace. In recent years, due to changes in product structure, more and more high-value-added products need to go through the RH process, especially the increase in the output of heavy rails, which has led to an increase in the proportion of RH furnace processing year by year. Therefore, it is necessary to increase the service life of the RH vacuum tank and reduce the number of RH furnace processing times to stabilize production, improve product benefits and reduce production costs. In the actual production and use process, the main bottleneck affecting the service life of the RH vacuum tank in a single cycle is the service life of the circulation tube that directly contacts the molten steel. The average number of furnaces that have been offline for the RH furnace tank age in our factory is 58. The main reason for the offline is that the circulation tube has a large amount of wear and tear, which easily leads to the phenomenon of burning through the bottom of the tank. The original brick thickness of the circulation tube is 170mm. During use, the crotch position of the circulation tube brick on the rising side is the most severely eroded. The thickness of the remaining bricks offline is 30mm, which is relatively thin and prone to troughing accidents. The residual height of the circulation tube offline is about 550mm, and about 150mm has been eroded. The shortening of the circulation tube is a limiting link in increasing the number of furnaces.

[0004] In order to further improve the service life of the empty tank, it is necessary to optimize the circulation pipe structure and masonry technology to increase the service life of the vacuum tank and reduce production costs. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a masonry method for a circulating flow pipe at the bottom of a vacuum tank, so as to increase the service life of the vacuum tank.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention includes the following steps: S1. The circulation pipe is divided into an ascending circulation pipe group and a descending circulation pipe group, located on both sides of the center of the bottom of the tank; S2. The circulation pipe is composed of an upper and lower layer of circulation pipe bricks, the upper circulation pipe bricks are staggered in two heights, and the lower circulation pipe bricks are staggered in two heights, and the circulation pipe height after masonry is consistent; S3. The bottom of the tank is built by the lower layer of fused rebonded magnesia-chrome bricks and the upper layer of directly bonded magnesia-chrome bricks around the circulation pipe bricks, and the gaps are filled with rebonded magnesia-chrome ramming materials; S4. After the trough bottom is built, a layer of fused and combined magnesium-chrome trough wall bricks is vertically laid above the circulating pipe bricks of the ascending circulating pipe group; S5. The outer sides of the upper circulation pipe are the working layer, permanent layer, thermal insulation layer, heat insulating layer and tank steel shell in order; S6. Use self-flowing material to pour between the lower circulation pipe bricks and the tank steel shell; fill the gap between the upper circulation pipe bricks and the tank bottom bricks with magnesium-chromium ramming material and ram it firmly; S7. The triangle area enclosed by the circulating pipe bricks, pipe wall bricks and trough bottom bricks is filled with fused rebonded magnesia-chrome bricks and rebonded magnesia-chrome ramming materials; S8. The bottom of the circulation pipe group is welded to the immersion pipe, and the vertical joints of the immersion pipe and the circulation pipe bricks should be staggered.

[0007] Furthermore, in step S2, the upper circulation pipe bricks (3) are constructed by staggered laying of bricks of two heights, 350±50 mm and 400±50 mm, and the lower circulation pipe bricks (4) are constructed by staggered laying of bricks of two heights, 350±50 mm and 300±50 mm, and the total height of the circulation pipe is 700±100 mm.

[0008] Furthermore, in step S2, the thickness of the upper circulating pipe brick (3) is 200±20 mm, and the thickness of the lower circulating pipe brick (4) is 170±20 mm.

[0009] Furthermore, in step S2, the top of the circulating pipe brick near the center of the tank bottom is a curved structure.

[0010] Furthermore, in step S7, the ramming material is rammed at least 6 times, and each ramming cycle lasts for 3 to 5 minutes.

[0011] The beneficial effects of adopting the above technical solution are: 1. The upper circulating pipe bricks of the present invention are staggered and laid in sequence at different heights, and the lower circulating pipe bricks are staggered and laid in sequence at different heights. The layers are staggered and interlocked with each other, the ring bricks are bonded, and the circulating pipe bricks are staggered and laid in a way that enhances their ability to resist erosion by molten steel and improves the service life of the vacuum tank. In particular, when the thickness of the upper circulating pipe bricks is increased to 200±20mm, the corrosion resistance is enhanced, the probability of steel leakage and slot penetration accidents is basically eliminated, and the service life of the vacuum tank is further improved; 2. The present invention designs the upper part of the circulating pipe brick near the center of the tank bottom as an arc structure, in order to reduce the erosion of the upper circulating pipe brick by the molten steel; 3. The present invention lays a layer of electric fusion combined with magnesium-chromium groove wall bricks above the circulating pipe bricks of the ascending circulating pipe group, which effectively protects the circulating pipe bricks on the upper edge and effectively improves the service life of the circulating pipe bricks; 4. The triangular area is large and is subject to strong scouring and erosion, and this position is relatively weak. In addition to using electric melting combined with magnesia-chrome bricks for masonry, the present invention uses at least 6 times of filler ramming to strengthen the construction of ramming materials in this part, and each ramming takes 3 to 5 minutes. This effectively reduces the situation where the area is first eroded by molten steel due to low density; 5. The present invention effectively reduces the degree of erosion of the circulating pipe by molten steel, reduces the occurrence of slot penetration accidents, increases the service life of the vacuum tank, and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0013] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a structural schematic diagram of the circulating flow pipe group of the present invention; Figure 3 It is a top view of the groove bottom structure of the present invention.

[0014] In the figure: ascending circulation pipe group 1, descending circulation pipe group 2, upper circulation pipe bricks 3, lower circulation pipe bricks 4, electro-fused and re-bonded magnesia-chrome bricks 5, directly bonded magnesia-chrome bricks 6, re-bonded magnesia-chrome ramming material 7, electro-fused and re-bonded magnesia-chrome tank wall bricks 8, working layer 9, permanent layer 10, thermal insulation layer 11, heat insulation layer 12, tank body steel shell 13, triangular area 14, immersion pipe 15, arc structure 16. DETAILED DESCRIPTION

[0015] Figure 1 , 2 As shown in Figure 3, the masonry method of the vacuum tank bottom circulation pipe comprises the following steps: S1. The circulation pipes are divided into ascending circulation pipe group 1 and descending circulation pipe group 2, which are located on both sides of the center of the trough bottom.

[0016] S2. The ascending circulation pipe group 1 and the descending circulation pipe group 2 are both built by combining upper and lower layers of circulation pipe bricks. The upper circulation pipe bricks 3 are built in two heights of 350±50mm and 400±50mm, and the lower circulation pipe bricks 4 are built in two heights of 350±50mm and 300±50mm, and are built in two heights; the layers are staggered and interlocked with each other, and the ring bricks are bonded to each other; the height of the circulation pipes after masonry is consistent, and the total height is 700±100mm; the thickness of the upper circulation pipe bricks 3 is thicker than that of the lower circulation pipe bricks 4, and the upper circulation pipe bricks 3 and the lower circulation pipe bricks 4 are aligned in the inner vertical direction, preferably the thickness of the upper circulation pipe bricks 3 is 200±20mm, and the thickness of the lower circulation pipe bricks 4 is 170±20mm; the upper part of the circulation pipe bricks near the center of the bottom of the trough is an arc structure 16, the purpose of which is to reduce the erosion of the upper circulation pipe bricks by the molten steel.

[0017] S3. The bottom of the trough is built around the circulation pipe with the lower layer of fused rebonded magnesia-chrome bricks 5 and the upper layer of directly bonded magnesia-chrome bricks 6, and the gaps are filled with rebonded magnesia-chrome ramming materials 7. When building the bottom of the trough, an annular gap is left between the built magnesia-chrome bricks and the circulation pipe, and the annular gap is controlled to be 50mm-60mm. The gaps in the annular gaps are filled with rebonded magnesia-chrome ramming materials 7, and then rammed to make the brickwork surface of the bottom of the trough flat, with a brick gap of ≤1 mm. After masonry, the upper surface of the trough bottom is flush with the upper surface of the circulation pipe, especially the flatness of the part of the circulation pipe and the bottom of the trough pressed by the trough wall, which shall not exceed 2mm. If it exceeds this range, it shall be polished.

[0018] S4. After the trough bottom is built, a layer of fused and combined magnesium-chromium trough wall bricks 8 is vertically built close to the inner wall of the trough body above the circulating pipe bricks in the ascending circulating pipe group 1 to effectively protect the circulating pipe bricks on the upper edge.

[0019] S5. The outer side of the upper circulation pipe is the tank wall, which is composed of the working layer 9, permanent layer 10, thermal insulation layer 11, heat insulating layer 12 and tank steel shell 13 from the inside to the outside; the working layer 9 is made of fused rebonded magnesia-chrome bricks, the permanent layer 10 is made of directly bonded magnesia-chrome bricks, the thermal insulation layer 11 is made of high-alumina bricks, and the heat insulating layer 12 is made of calcium silicon insulation board.

[0020] S6. The lower circulation pipe bricks and the tank steel shell 13 are poured with self-flowing material; the upper circulation pipe bricks 3 and the brick seams at the bottom of the tank are filled with magnesium-chromium ramming material 7, which is rammed firmly to a standard of smooth surface.

[0021] S7. The triangular area 14 surrounded by the bricks of the circulating pipe, the bricks of the groove wall and the bricks of the groove bottom is relatively large. This area is strongly eroded and corroded and is relatively weak. Therefore, the triangular area 14 is filled with fused rebonded magnesia-chrome bricks 5 and rebonded magnesia-chrome ramming materials 7; the ramming materials are rammed at least 6 times, and each ramming takes 3 to 5 minutes; the surface is smooth with ramming firmness as the standard, which can effectively reduce the situation where the area is first eroded by molten steel due to low density.

[0022] S8. The lower part of the circulation pipe is welded to the immersion pipe 15, and the vertical seams between the immersion pipe 15 and the circulation pipe bricks should be staggered.

[0023] Example: Figure 1 , 2 As shown in Figures 3 and 4, the masonry method of the bottom circulation pipe of the vacuum tank is specifically described as follows.

[0024] S1. The circulation pipes are divided into ascending circulation pipe group 1 and descending circulation pipe group 2, located on both sides of the center of the trough bottom; S2. The circulation pipe group is composed of upper and lower layers of circulation pipe bricks. The upper circulation pipe bricks 3 are staggered with 350mm and 400mm in sequence, and the lower circulation pipe bricks 4 are staggered with 350mm and 300mm in sequence. The layers are staggered and interlocked with each other, and the ring bricks are bonded. The circulation pipe bricks are staggered. In order to enhance its ability to resist erosion by molten steel, the height of the circulation pipe after masonry is 700mm. The thickness of the lower circulation pipe bricks is 170mm, while the thickness of the upper circulation pipe bricks is increased to 200mm, in order to enhance its corrosion resistance, prevent steel leakage and slot penetration accidents, and thus increase the service life of the vacuum tank; S3. The bottom of the trough is built around the circulation pipe bricks by fused rebonded magnesia-chrome bricks 5, directly bonded magnesia-chrome bricks 6 and rebonded magnesia-chrome ramming materials 7. When laying the trough bottom bricks, the annular gap with the circulation pipe is controlled to be 50mm to 60mm, and the gap is filled with rebonded magnesia-chrome ramming materials 7. The bricklaying surface is flat, and the brick gap is ≤1mm. The upper surface of the trough bottom bricks is level with the upper surface of the circulation pipe bricks, especially the flatness of the circulating pipe bricks and the furnace bottom bricks pressed by the trough wall bricks. It is not allowed to exceed 2mm. Those exceeding this range shall be polished. The upper part of the circulation pipe bricks near the center of the trough bottom is designed as an arc structure, the purpose is to reduce the erosion of the upper circulation pipe bricks by the molten steel; S4. After the bricks are built, above the circulating pipe group of the rising circulating pipe bricks, a layer of fused bricks is laid in combination with magnesium-chrome groove wall bricks 8 to effectively protect the upper edge of the circulating pipe bricks; S5. The outer side of the upper circulation pipe is the working layer 9, the permanent layer 10, the insulation layer 11, the heat insulation layer 12, and the tank steel shell 13; S6. Between the lower circulation pipe brick 4 and the tank steel shell 13, use self-flowing material to cast, and between the upper circulation pipe brick 3 and the bottom brick seam of the tank is filled with magnesium-chromium ramming material, which is rammed firmly, and the standard is a smooth surface; S7. The triangular area 14 formed by the bricks of the circulation pipe, the bricks of the trough wall and the bricks of the trough bottom is relatively large. This area is strongly eroded and eroded and is relatively weak. In addition to the use of electric fusion combined with magnesia-chrome bricks for masonry, in order to strengthen the construction of ramming materials in this area, the ramming materials are divided into 6 times, and each time less filling and more ramming, the time is 3 to 5 minutes per circle, and the ramming is taken as the standard, the surface is flat, and the situation that the area is first eroded by molten steel due to low density is effectively reduced; S8. The lower part of the circulation pipe is welded to the immersion pipe 15, and the vertical joints of the immersion pipe 15 and the circulation pipe bricks should be staggered.

[0025] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention is described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for laying a vacuum tank bottom circulation pipe, characterized in that: The steps include: S1. The circulation pipe is divided into an ascending circulation pipe group (1) and a descending circulation pipe group (2), which are located on both sides of the center of the bottom of the trough; S2. The circulation pipe is composed of an upper and lower layer of circulation pipe bricks, the upper circulation pipe bricks (3) are staggered in two heights, and the lower circulation pipe bricks (4) are staggered in two heights, and the circulation pipe height after masonry is consistent; S3. The bottom of the tank is made of a lower layer of fused and bonded magnesia-chrome bricks (5), an upper layer of directly bonded magnesia-chrome bricks (6) built around the circulation pipe bricks, and the gaps are filled with bonded magnesia-chrome ramming materials (7); S4. After the bottom of the trough is built, a layer of fused magnesium-chromium trough wall bricks (8) is vertically laid above the circulating pipe group (1) circulating pipe bricks; S5. The outer side of the upper circulation pipe is the working layer (9), the permanent layer (10), the thermal insulation layer (11), the heat insulation layer (12) and the tank steel shell (13); S6. Between the lower circulation pipe brick (4) and the tank steel shell, pouring with self-flowing material; between the upper circulation pipe brick (3) and the bottom brick seam of the tank is filled with magnesium-chromium ramming material (7) and rammed firmly; S7. The triangular area (14) formed by the circulating pipe bricks, the pipe wall bricks and the groove bottom bricks is filled with fused rebonded magnesia-chrome bricks and rebonded magnesia-chrome ramming materials; S8. The lower part of the circulation pipe group is welded to the immersion pipe (15), and the vertical joints of the immersion pipe (15) and the circulation pipe bricks should be staggered.

2. The method for laying a vacuum tank bottom circulation pipe according to claim 1, characterized in that: In step S2, the upper circulation pipe bricks (3) are constructed by staggered laying of bricks of two heights, 350±50 mm and 400±50 mm, and the lower circulation pipe bricks (4) are constructed by staggered laying of bricks of two heights, 350±50 mm and 300±50 mm, so that the total height of the circulation pipe is 700±100 mm.

3. The method for laying a vacuum tank bottom circulation pipe according to claim 1, characterized in that: In the step S2, the thickness of the upper circulating pipe brick (3) is 200±20 mm, and the thickness of the lower circulating pipe brick (4) is 170±20 mm.

4. The method for laying a vacuum tank bottom circulation pipe according to claim 1, characterized in that: In the step S2, the top of the circulating pipe brick near the center of the tank bottom is an arc structure.

5. A method for laying a vacuum tank bottom circulation pipe according to any one of claims 1 to 4, characterized in that: In step S7, the ramming material is rammed in 6 times, and each ramming time is 3 to 5 minutes.

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