A steel penetration resistant rh refining vessel dip tube and use thereof

Abstract

The application discloses a RH refining furnace immersion tube capable of preventing steel penetration, and the butt joint surface of a circulation pipe and immersion tube lining brick and the butt joint flange of a steel structure are staggered and built, the butt joint surface and the flange surface are staggered and built, and corundum self-flowing material is used for blocking, so that even if the welding quality of the flange or the butt joint surface of the immersion tube and the circulation pipe is poor, the steel penetration accident cannot be caused, and the safe use performance of the RH furnace is improved.

Description

Technical Field

[0001] This invention belongs to the field of vacuum smelting technology, specifically relating to a steel-penetration-resistant RH refining furnace impregnation tube and its application. Background Technology

[0002] In recent decades, with the continuous development of the steelmaking industry, RH ladle refining technology has made great progress. It removes harmful gases such as hydrogen and nitrogen from molten steel and reduces carbon content by using the principle of vacuum circulation degassing, thereby further improving the purity of molten steel and ensuring its quality.

[0003] As the technology matures, the operating environment and usage requirements for RH furnaces become increasingly stringent. The furnace has evolved from a single dehydrogenation function to multiple functions including decarburization, temperature compensation, composition adjustment, and alloying. With this diversification, the single-furnace vacuum treatment time for RH refining furnaces has also increased. This has led to a corresponding increase in the steel throughput time and volume of the impregnation tubes and circulation tubes, from 15 minutes to 40 minutes, representing a 1.67-fold increase in throughput. Due to limitations in the tank structure and on-site construction, the traditional design places the upper surface of the impregnation tube, the lower surface of the circulation tube, and the tank flange on the same horizontal plane, forming a continuous seam. During use, issues such as lining quality, butt joint quality, and flange welding quality can cause steel entrapment or air suction at the joint surface. With continuous use, the entrapment area increases and deepens, eventually penetrating the joint and burning through the flange, causing a steel penetration accident. This affects the overall quality of the RH furnace, reduces the service life of the impregnation tubes, and disrupts the steel plant's production schedule.

[0004] Therefore, how to provide a steel-penetrating RH refining furnace impregnation tube is an urgent problem to be solved. Summary of the Invention

[0005] In view of this, the present invention provides an anti-penetration RH refining furnace impregnation tube and its application. The mating surface and the flange surface are staggered and the corundum self-flowing material is used for blocking. Even if there are problems with the flange welding quality or steel piercing at the mating surface of the impregnation tube and the circulation tube, it will not lead to a steel penetration accident, thus improving the safe operation of the RH furnace.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A steel-penetrating RH refining furnace impregnation tube is constructed with staggered joints at the mating surfaces of the circulation tube and the impregnation tube lining bricks and the mating flanges of the steel structure.

[0008] Preferably, the mating surface between the circulating pipe and the impregnated pipe lining brick is 50-100mm higher than the mating flange.

[0009] Preferably, the mating surface between the circulating pipe and the impregnated pipe lining brick is 100mm higher than the mating flange.

[0010] Preferably, the height of the circulation tube is shortened by 100mm.

[0011] This invention extends the upper surface of the lining brick of the impregnation tube by 100mm beyond the flange face, shortens the total height of the circulation tube by 100mm, and keeps the position of the structural flange face unchanged. The outer side of the lining brick is filled with corundum self-flowing material. This allows for staggered construction of the mating surface and the flange face, while the corundum self-flowing material is blocked. Even if there are problems with the flange welding quality or steel piercing at the mating surface of the impregnation tube and the circulation tube, it will not lead to steel penetration accidents, thus improving the safe operation of the RH furnace.

[0012] Preferably, the impregnation tube further includes a self-flowing material and an outer casting material.

[0013] Preferably, the impregnated pipe lining brick comprises the following raw materials by weight percentage: MgO 81-85%, Al2O3 10-12%, antioxidant 3-4%, and binder 2-3%.

[0014] Preferably, the impregnated pipe lining brick is made of unburned magnesia spinel lining brick material, with the following raw materials in parts by weight: 68-80 parts of large crystalline magnesia particle size material, 8-12 parts of 98 large crystalline magnesia powder, 2.5-3 parts of binder, 5-6 parts of antioxidant aluminum powder, 1.5-2.5 parts of yttrium stabilized zirconium oxide, and 7-10 parts of alumina powder.

[0015] This invention uses large-crystal fused magnesia with an MgO content ≥98%, possessing large primary crystal grains and excellent resistance to penetration and erosion. The binder is phenolic resin with a residual carbon content ≥40%. Because phenolic resin is composed of many carbon atoms, it forms a strong carbon bond during high-temperature sintering. Compared to traditional binders such as tar and pitch, phenolic resin has advantages such as high heat hardening, high drying strength, high fixed carbon rate, and low environmental pollution. The antioxidant is metallic aluminum powder, selected in powder form with an elemental aluminum content ≥98%. At high temperatures, the aluminum powder will… The aluminum carbide reacts chemically with the residual carbon in the resin to form aluminum carbide that is encapsulated on the surface of the lining bricks to protect against the penetration and erosion of the slag. The stabilized zirconia is selected with a zirconia content of ≥90% and a yttrium oxide content of ≥7%, which has excellent high-temperature properties such as good thermal shock resistance, high toughness, crack resistance, high temperature resistance, and good chemical stability. Alumina micro powder: Alumina micro powder with an alumina content of ≥99% and a particle size of ≤5μm is selected. It helps the sintering of the lining bricks at high temperatures and reacts with magnesia to form in-situ magnesia-alumina spinel, which has good erosion resistance and improves thermal shock resistance.

[0016] The impregnated tube lining bricks of this invention are formed by pressing with a 1200-1600t friction brick press and then dried in a 150-200℃ drying kiln. These lining bricks have good thermal shock stability, erosion resistance and other high-temperature properties, and can replace traditional magnesia-chrome bricks, with certain environmental advantages.

[0017] Preferably, the antioxidant is aluminum powder.

[0018] Preferably, the binder is a phenolic resin.

[0019] Preferably, the self-flowing material comprises the following raw materials by mass percentage: Al2O3 90-91%, MgO 2-3.5%, antioxidant 1.5-2.5%, and binder 4.5-5.5%.

[0020] The gaps between the impregnation pipe lining bricks and the steel structure, as well as between the circulation pipe lining bricks and the tank shell, are generally about 25-35mm thick and are filled with corundum self-flowing material. Plate-shaped corundum with good thermal shock stability is selected as the aggregate, and the binder is CA6, which has a fast hydration rate and easily forms a high-temperature phase. This material has good construction fluidity, good high-temperature strength, and high bulk density, which can effectively fill the gaps and fix the circulation pipe and impregnation pipe lining bricks to prevent displacement.

[0021] Preferably, the outer casting refractory comprises the following raw materials by mass percentage: Al2O3 94.5-96%, CaO 1-2.5% and MgO 2-3%.

[0022] Preferably, the outer layer castable comprises the following percentages of raw materials: 61-70% tabular corundum, 15-16% sintered spinel, 5% alumina powder, 6-14% fused zircon-mullite, and 4% cement.

[0023] The tabular corundum of this invention uses Al2O3 with a content ≥99%, which has the advantages of high purity, high melting point, large grain hardness, and good wear resistance. The binder uses pure calcium aluminate cement, which has a fast hydration rate and easily forms the high-temperature phase CA6, thus exhibiting good high-temperature performance. The alumina micro powder is mixed in a single-peak and double-peak manner to achieve a denser packing effect, making the castable more compact and improving the erosion resistance of the material. The magnesium aluminum spinel micro powder has a particle size of 5-10μm, which has good thermal shock stability and high-temperature performance such as anti-permeability and anti-corrosion. Stainless steel fiber: Stainless steel fiber itself has the characteristics of high melting point and high strength, which can improve the strength and toughness of the castable blank and help suppress the formation of cracks in the castable.

[0024] The outer layer of the impregnated tube serves to protect the steel structure and lining bricks. Due to the continuous circulation and tumbling of the molten steel under the action of the RH vacuum system and bottom blowing, the outer layer of the impregnated tube is subjected to severe scouring and slag erosion. At the same time, due to the alternating use of hot and cold in the impregnated tube, the outer layer of the impregnated tube is required to have excellent thermal shock stability. This invention achieves excellent thermal shock stability and high-temperature performance such as scouring resistance and erosion resistance through processes such as on-site casting and vibration molding, curing for 8-10 days at 30-45℃ and 40%-60% humidity, and drying at 350-400℃.

[0025] The application of impregnated tubes in RH refining furnaces as described above.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention effectively reduces the risk of steel penetration in the tank, stabilizes the production rhythm, and improves the safety factor.

[0028] 2. The present invention reduces the amount of refractory material used, lowers the overall contracting cost, and improves the economic benefits of enterprises.

[0029] 3. The process flow of the present invention is the same as that of the traditional construction scheme, without any complexity. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0031] Figure 1 This is a comparison diagram of the structure of the present invention and the conventional structure, where A represents the conventional structure and B represents the structure of the present invention.

[0032] Among them, 1-circulation pipe, 2-self-flowing material, 3-steel structure, 4-joint between impregnated pipe and circulation pipe, 5-joint flange between impregnated pipe and steel structure, 6-impregnated pipe lining brick, 7-outer layer of impregnated pipe casting material. Detailed Implementation

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] Example 1

[0035] A method for preparing a steel-penetration-resistant RH refining furnace impregnation tube specifically includes the following steps:

[0036] 1. Preparations before the assignment

[0037] 1) Batching: Confirm that the raw material labels and indicators are qualified. Before batching, conduct a teaching weighing. The batching tolerance is ±0.5kg. The raw material ratios for impregnated pipe lining bricks (see Table 1 data), the raw material ratios for outer layer castable (see Table 2 data), and the raw material ratios for self-flowing material are as follows. Premix each component material for a premixing time of ≥25 minutes. The finished material storage time is ≤72 hours, and the storage temperature is 25-35℃.

[0038] 2) Mold assembly: Confirm the integrity of the mold, check for grout leakage, and ensure there are no loose bolts;

[0039] 3) Mixing: Put the impregnated pipe lining brick material into the mixing equipment, and mix for ≥3 minutes. Add 4.5% water for wet mixing, and after 3-4 minutes of wet mixing, discharge the material and vibrate to form the shape.

[0040] 4) Vibration molding: Pour the mixed clay into the mold and vibrate it for molding. The net vibration time is ≥3 minutes. Then place it in a horizontal position for curing. The curing temperature is 25-40℃. The curing time inside the mold is 10-15 hours. The curing time outside the mold is ≥240 hours. Then put it into the kiln for drying.

[0041] 5) Drying: Place the impregnated tubes that have reached the curing period into a drying kiln, dry at 380℃, and dry for ≥98 hours.

[0042] 2. Impregnated pipe connection

[0043] 1) The surfaces of the impregnation tube lining brick and the circulation tube should be clean and free of impurities. Place the circulation tube on the upper surface of the impregnation tube lining brick, and ensure that the inner holes are concentric.

[0044] 2) The joint surface between the impregnated pipe lining bricks and the circulation pipe must be dry-laid;

[0045] 3) The impregnation pipe lining bricks are slowly raised using a lifting vehicle until the flange face of the impregnation pipe lining bricks is completely in contact with the flange of the tank body; the upper surface of the impregnation pipe lining bricks protrudes 100mm from the flange face, the total height of the circulation pipe is shortened by 100mm, and the position of the structural flange face remains unchanged.

[0046] 4) Use 506 welding rods to continuously weld the entire circumference of the flange joint at least 3 times, ensuring there are no pinholes and the weld is full;

[0047] 5) Cast corundum self-flowing material, wherein the mass percentage of corundum self-flowing material is: Al2O3 90-91%, MgO 2-3.5%, antioxidant 1.5-2.5% and binder 4.5-5.5%;

[0048] 3. Construction of corundum castable refractory for circulation pipe

[0049] 1) After determining and fixing the positions of the impregnation pipe lining bricks and the circulation pipe, the corundum castable refractory for the circulation pipe is poured.

[0050] 2) First, put the castable into the mixer, dry mix for 2-3 minutes, then wet mix for 3-4 minutes, with a water content of about 8-9%.

[0051] 3) The refractory material mixed with water must be used within 30 minutes, and construction must not be interrupted arbitrarily.

[0052] 4) Pour the material in sequence during pouring, then vibrate with an immersion vibrator. When using a vibrator, start the vibrator before inserting it into the refractory. During vibration, the vibrator should be inserted straight in, quickly inserted, and slowly withdrawn.

[0053] 5) Allow natural curing for ≥24 hours after pouring.

[0054] like Figure 1 To distinguish the structure of this invention from that of traditional processes, this invention optimizes the design by extending the upper surface of the lining brick of the impregnation tube 100mm beyond the flange face, shortening the total height of the circulation tube by 100mm, while keeping the position of the flange face unchanged. The outer side of the lining brick is filled with corundum self-flowing material. This allows for staggered construction of the mating surface and the flange face, while the use of corundum self-flowing material for blocking. Even if there are quality problems with the flange welding or steel piercing at the mating surface of the impregnation tube and the circulation tube, it will not lead to steel penetration accidents, thus improving the safe operation of the RH furnace.

[0055] Example 2

[0056] The raw material ratios for the impregnated pipe lining bricks (see Table 1 data) and the raw material ratios for the outer layer castable (see Table 2 data) are exactly the same as those in Example 1.

[0057] Example 3

[0058] The raw material ratios for the impregnated pipe lining bricks (see Table 1 data) and the raw material ratios for the outer layer castable (see Table 2 data) are exactly the same as those in Example 1.

[0059] Table 1 Raw material ratio for impregnated pipe lining bricks

[0060]

[0061] Table 2 Raw material proportions for outer layer castable

[0062]

[0063]

[0064] Application examples

[0065] Taking a 210t RH furnace in a large steel plant in Hunan Province as an example, this branch plant has been in operation for more than 20 years. The original design had the impregnation pipe and circulation pipe mating surfaces and the flange mating surfaces on the same plane. After two years of use, the steel penetration rate was approximately 0.375%, but the steel penetration rate at the mating surfaces accounted for about 60% of the total steel penetration rate. After adjusting the design, the steel penetration rate was approximately 0.125%, and the steel penetration caused by air intake and steel bridging at the mating surfaces accounted for 15% of the total steel penetration rate, a decrease of about 45%. The actual verification shows that the design scheme of Example 1 has a positive practical performance for industrial production, can bring certain economic benefits to enterprises, and more importantly, improves the safe, continuous and stable production capacity of the user unit.

[0066] The various embodiments are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between the various embodiments can be referred to each other.

[0067] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A steel penetration resistant RH refining vessel dip tube, characterized by, The butt joint surface of the loop pipe and the impregnation pipe lining brick and the butt joint flange of the steel structure are staggered and laid; the impregnation pipe further comprises self-flowing material and outer layer castable; The impregnation pipe lining brick is made of unfired magnesia spinel lining brick material, and the following raw materials by weight: 68-80 parts of coarse crystalline magnesia granular material, 8-12 parts of 98 coarse crystalline magnesia powder, 2.5-3 parts of binder, 5-6 parts of antioxidant aluminum powder, 1.5-2.5 parts of yttrium stabilized zirconia, and 7-10 parts of alumina powder; the binder is phenolic resin; The outer layer castable comprises the following raw materials by mass percentage: 61-70% tabular corundum, 15-16% sintered spinel, 5% alumina micropowder, 6-14% fused zirconium mullite, and 4% cement.

2. A steel penetration preventing RH refining furnace immersion tube according to claim 1, characterized in that The butt joint surface of the loop pipe and the impregnation pipe lining brick is 50-100 mm higher than the butt joint flange.

3. A steel penetration resistant RH refining vessel dip tube according to claim 2, wherein, The butt joint surface of the loop pipe and the impregnation pipe lining brick is 100 mm higher than the butt joint flange.

4. A steel penetration resistant RH refining vessel dip tube according to claim 1, wherein, The self-flowing material comprises the following raw materials by mass percentage: 90-91% Al2O3, 2-3.5% MgO, 1.5-2.5% antioxidant, and 4.5-5.5% binder.

5. The application of the impregnation pipe in the RH refining furnace according to any one of claims 1-4.

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