Repairing method of gas leakage part

Abstract

To provide a repairing method of a gas leakage part capable of securing sufficient airtightness and being easily executed even if the gas leakage part has a complicated shape.SOLUTION: In a repairing method of a gas leakage part, a repairing material formed of a material at least a part of which is melted at a temperature of 1400°C and containing 90 wt.% or more of particles of 2 mm or less in a particle size distribution and a liquid containing 14% or more and 28% or less of water as a main component in terms of an external number with respect to the mass of the repairing material are mixed, and a gas leakage part of a blast furnace is repaired by spraying the mixture to the gas leakage part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for repairing a gas leakage part of a blast furnace, which repairs the gas leakage part of the blast furnace.

Background Art

[0002] Although blast furnaces are regularly repaired, even after repair, high-temperature gas in the blast furnace may leak due to some problems. For example, the tuyere through which high-temperature gas is blown into the blast furnace protrudes inside the furnace, and when ore descends onto the tuyere, etc., there may be a slack at the mating part between the tuyere and the tuyere cooling box, and high-temperature gas may leak from this location. Not limited to such events, cracks may occur in the iron skin of the blast furnace due to aging, etc., and gas may leak from the blast furnace.

[0003] Patent Document 1 discloses a technique of sucking high-temperature gas by a suction pipe connected to a dust collector when high-temperature gas leaks from a tuyere. Also, a method of repairing a gas leakage part by pressing an amorphous refractory against the gas leakage part is known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, with the technique described in Patent Document 1, the blast furnace cannot be repaired. Also, the technique of pressing an amorphous refractory against the gas leakage part has a problem in airtightness and is difficult to construct while avoiding complex piping.

[0006] An object of the present invention is to provide a method for repairing a gas leakage part that ensures sufficient airtightness even when the gas leakage part has a complex shape and is easily constructible.

Means for Solving the Problem

[0007] [1] A repair material formed of a material that at least partially softens and melts at a temperature of 1400 °C and having 90% by weight or more of particles of 2 mm or less in the particle size distribution, and a liquid mainly composed of 14% to 28% by weight of water based on the mass of the repair material are mixed and sprayed onto the gas leakage part of the blast furnace to repair the gas leakage part. A method for repairing a gas leakage part. [2] The method for repairing a gas leakage part according to [1], wherein the material has an alumina content of 25% by mass or more and 75% by mass or less. [3] The method for repairing a gas leakage part according to [2], wherein the material has a silica content of 25% by mass or more and 75% by mass or less. [4] The method for repairing a gas leakage part according to [2], wherein the material has a calcium oxide content of 15% by mass or less. [5] The method for repairing a gas leakage part according to any one of [1] to [4], wherein the gas leakage part is a gap formed between metal parts.

Advantages of the Invention

[0008] According to the present invention, by spraying a repair material mixed with water onto the gas leakage part of the blast furnace in a high-temperature gas atmosphere, the repair material melts and then solidifies. Thereby, the gas leakage part can be repaired while ensuring sufficient airtightness. Further, by mixing and spraying the repair material and a liquid mainly composed of water, even when the shape of the gas leakage part is complicated, the repair can be surely performed.

Brief Description of the Drawings

[0009]

Figure 1

Embodiments for Carrying Out the Invention

[0010] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Figure 1 is a partial cross-sectional view of a blast furnace to which a repair method according to an embodiment of the present invention is applied. The blast furnace is covered with an iron skin 1 made of steel plate, and the inside is lined with a refractory brick layer 2. The tuyere 3 in the shape of a nozzle is formed of, for example, copper, and introduces high-temperature gas introduced from the blow pipe 4 into the blast furnace. The tuyere 3 is supported by a tuyere cooling box 5, and the tuyere cooling box 5 is fixed to the iron skin 1 by a holding fitting 6.

[0011] Hereinafter, a method for repairing a gas leakage part in the case of gas leakage in the blast furnace will be described. The method for repairing the gas leakage part includes a step of preparing a repair material and a step of spraying the repair material mixed with water onto the gas leakage part.

[0012] Examples of cases where gas leakage occurs include the following cases. 〔1〕Due to the descent of ore to the tuyere 3 or the like, a slack occurs at the mating part between the tuyere 3 and the tuyere cooling box 5, and high-temperature gas leaks from the part. 〔2〕Similarly, due to the descent of ore to the tuyere 3 or the like, a slack occurs at the mating part between the tuyere 3 and the blow pipe 4, and high-temperature gas leaks from the part. 〔3〕Cracks occur in the iron skin 1 due to aging or the like, and high-temperature gas leaks from the cracks. In the present invention, the gas leakage part formed in the cases listed above is repaired with a repair material.

[0013] Next, the repair material will be described. The repair material is fine powder particles and is formed of a material that at least partially softens and melts at a temperature of 1400°C. In order to exhibit such a function, the material constituting the repair material contains about 50% by mass of alumina (Al2O3). Specifically, the material preferably has an alumina content of 25% by mass or more and 75% by mass or less, more preferably 32% by mass or more and 62% or less. The material preferably has a silica (SiO2) content of 25% by mass or more and 75% by mass or less, more preferably 34% by mass or more and 64% or less. Further, the material preferably has a calcium oxide (CaO, lime) content of 15% by mass or less. Most preferably, the material has an alumina content of 39% by mass or more and 49% by mass or less, a silica content of 43% by mass or more and 53% by mass or less, and a calcium oxide content of 3% by mass or more and 8% by mass or less. The material may also contain iron oxide or titanium oxide. Such a material has a small linear change rate of -0.2% and excellent compressive strength of 20 MPa or more.

[0014] The fact that the material mainly composed of the above alumina, silica, and calcium oxide softens and melts at least partially at 1400°C is described, for example, in Kiyohiko Ikeda et al., "Production of Glass and Glass Ceramics from Industrial Wastes Using the CaO-Al2O3-SiO2 Ternary Equilibrium Phase Diagram", The Japan Society of Mechanical Engineers, Transactions of the Japan Society of Mechanical Engineers (Series A) 78, No. 789, pp. 98-102.

[0015] The maximum particle size of the repair material, which is fine powder particles, is 2 mm. However, a part of the maximum particle size may be larger than 2 mm. Specifically, for example, in the particle size distribution determined by the laser diffraction / scattering method, particles of 2 mm or less may account for 90% by weight or more.

[0016] Next, the mixing amount of water will be described. The mixing amount of water is set to an appropriate amount that does not flood the inside of the blast furnace. Specifically, the mixing amount of water is 14% or more and 28% or less by weight based on the mass of the repair material. Note that the water to be mixed may contain other liquids, as long as the liquid has water as the main component.

[0017] In the step of preparing the repair material, the above-described repair material is prepared and loaded into the spraying device. The spraying device has a material tank for storing repair material, a hose for pneumatically conveying the repair material from the material tank, a water addition section for adding water to the air-conveyed material via the hose, and a nozzle for spraying the repair material and water.

[0018] In the step of spraying the repair material onto the gas leakage part, the operator sprays the repair material and water toward the gas leakage part. Spraying can be performed from the outside during the operation of the blast furnace. The air volume during spraying is preferably 1200 liters / minute or more and 1500 liters / minute or less, and the ejection volume is preferably 150 kg / hour or more and 900 kg / hour.

[0019] When the repair material mixed with water is sprayed onto the gas leakage part of the blast furnace, at least a part of the repair material melts due to the temperature of the high-temperature gas atmosphere in the gas leakage part being at least 1400°C. The melted repair material adheres to the periphery of the gas leakage part so as to block the gas leakage part. The operator continues spraying until the thickness of the adhered repair material becomes 1 cm or more. After that, as the temperature of the repair material drops, the repair material solidifies and the gas leakage part is repaired.

[0020] According to the above embodiment, by spraying the repair material mixed with water onto the gas leakage part of the blast furnace, which is a high-temperature gas atmosphere, the repair material melts and then solidifies. Thereby, the gas leakage part can be repaired while ensuring sufficient airtightness. Also, by mixing the repair material and a liquid mainly composed of water and spraying them, even when the shape of the gas leakage part is complex, the repair can be surely performed.

[0021] Also, when the gas leakage part is a gap formed between metal parts, for example, the rubbing part between tuyere 3 and tuyere cooling box 5, the adhesion of the repair material is high and the repair can be made stronger.

Example

[0022] Next, embodiments of the present invention will be described. In the embodiment, a pseudo gas leakage portion was formed in a blast furnace as described with reference to FIG. 1, and the repair method of the present invention was applied. High-temperature gas at 1400°C was made to leak from the gas leakage portion. The composition of the repair material in the embodiment is shown below.

[0023] ≪Composition of repair material≫ Aluminum oxide (Al2O3): 39% - 49% Silica (SiO2): 43% - 53% Calcium oxide (CaO): 3% - 8% Iron oxide (Fe2O3): <2% Titanium oxide (TiO2): <2%

[0024] The repair material as described above was prepared and sprayed onto the gas leakage portion together with water using a predetermined spraying device. At this time, the mixing amount of water was 14% or more and 28% or less by mass with respect to the repair material. As a result, after the repair material was softened and melted by the high-temperature gas and then solidified, the gas leakage portion could be repaired without problems.

Explanation of symbols

[0025] 1... iron skin, 2... refractory brick layer, 3... tuyere, 4... blow pipe, 5... tuyere cooling box, 6... holding fixture.

Claims

1. A repair material formed of a material that at least partially softens and melts at a temperature of 1400°C and having 90% by weight or more of particles of 2 mm or less in particle size distribution, and a liquid mainly composed of 14% to 28% by weight of water based on the mass of the repair material are mixed and sprayed onto a gas leakage part of a blast furnace to repair the gas leakage part. A method for repairing a gas leakage part.

2. The method for repairing a gas leakage part according to claim 1, wherein the material has an alumina content of 25% by mass or more and 75% by mass or less.

3. The method for repairing a gas leakage part according to claim 2, wherein the material has a silica content of 25% by mass or more and 75% by mass or less.

4. The method for repairing a gas leakage part according to claim 2, wherein the material has a calcium oxide content of 15% by mass or less.

5. The method for repairing a gas leakage part according to any one of claims 1 to 4, wherein the gas leakage part is a gap formed between metal parts.

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