JPH09210567A - Thermal spray repair layer and repair method for furnace wall - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To prevent the thermal spray repair layer of a furnace wall from peeling from the interface between the furnace wall brick and the thermal spray repair layer. SOLUTION: The mixing ratio of easily oxidizable metal particles in the thermal spray repair material is increased, and the temperature of the base furnace wall immediately before melting repair is made higher than the melting point of the easily oxidizable metal compounded in the thermal spray material,
By increasing the flame temperature for forming the thermal spray repair layer near the furnace wall side, a melt-solidified layer is present between the furnace wall surface and the thermal spray repair layer, and the adhesion of the thermal spray repair layer to the furnace wall is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal spray repair layer for an inner wall of an industrial kiln and a repair method. In particular, on the inner wall of the coke oven, the easily oxidizable metal powder and the powdery refractory are mixed with the oxygen-containing gas in the injection nozzle to be in a molten or semi-molten state, and a thermal spray repair layer obtained by hot spraying and Regarding repair methods.

[0002]

2. Description of the Related Art Industrial kilns, in particular, the inner wall of a furnace-construction structure as steel equipment, holds molten substances such as molten iron, molten steel, slag, and carbonized coal, and therefore is usually heated to a temperature of 1,000 ° C. or higher. When exposed, especially when pouring, storing, discharging, etc., the temperature of those inner walls changes remarkably. Therefore, not only the melt infiltrates and melts the inner walls, but also damages such as cracks and peeling occur. Therefore, in order to deal with various damage factors, it is necessary to select an appropriate brick material at the design or furnace construction stage.On the other hand, in order to extend the life of one furnace, repair work is performed at an intermediate stage of the operation period. It has become important to do so.

As a technique for repairing the furnace wall, a thermal spray repairing method in which a repairing material is hot sprayed on the damaged portion of the refractory has been actively tried. Particularly, in the coke oven, since the furnace temperature cannot be lowered and hot repair is essential, the thermal spray repair method is effective. Description will be given below by taking the furnace wall of the coke oven as an example. Generally, flame spray repair is performed by using so-called spray repair, which is a mixture of refractory powder or metal powder and refractory powder in the flame of flammable gas (propane gas, acetylene gas, etc.) and supporting gas (usually oxygen gas). Material is supplied, and these thermal spray repair materials are brought into a molten or semi-molten state to repair the damaged portion of the furnace wall. At this time, the temperature of the furnace wall is preferably high so that the thermal spray repair material is easily fused. Therefore, usually, the repair process is started immediately after the line work (after the coke is extruded in the coke oven, after the tapping slag is removed in the converter, etc.) to ensure the high temperature of the furnace wall.

From the above, for example, Japanese Patent Laid-Open No. 57-57
As disclosed in Japanese Patent No. 166489, a method of irradiating only a flame according to a furnace wall temperature and a wear condition, and subsequently spraying a spraying material to maintain the furnace wall at a high temperature, As in Japanese Patent Publication No. 58-6875,
By installing burners for preheating and heat retention before and after the thermal spray burner, and performing thermal spray repair while maintaining the furnace wall at a high temperature, and by observation with a television camera as in JP-A-60-17688. There is known a technique for repairing thermal spray while controlling the flame during spraying, the material supply amount, and the nozzle moving speed according to the furnace wall temperature so that the adhesion efficiency and strength are optimized.

A method for repairing the thermal spraying of the furnace wall is disclosed, for example, in Japanese Patent Publication No.
As disclosed in Japanese Patent Publication No. 45110, a powdered refractory is mixed with a combustible substance, and a combustion flame is generated by supplying a combustion-supporting gas, and the heat thereof causes the refractory to be in a molten or semi-molten state. It is a dry method of spraying on the damaged part of the inner wall. Therefore, the thermal-sprayed refractory has a feature that it retains high quality during use and its durability is significantly higher than that obtained by the conventional wet spraying method.

[0006]

Although the durability of the thermal spray repair layer is remarkably higher than that of the wet spraying method, it is necessary to further extend the durability in order to reduce the cost. By the way, as a result of observing the durability of the thermal spray repair layer in the coke oven, most of the thermal spray repair layer was peeled off from the interface between the furnace wall brick and the thermal spray repair layer, and was missing. It was found that almost no furnace wall bricks adhered to the interface.

On the basis of these observation results, the present invention improves the durability of the thermal spray repair layer of the furnace wall, and therefore the thermal spray repair layer and method for improving the adhesion between the furnace wall brick and the thermal spray repair layer. Is provided. Also, the thermal spray repair of the kiln is
As mentioned above, it is preferable to perform thermal spraying while maintaining the furnace wall at a high temperature. However, in many cases, it is practically difficult to carry out the thermal spray repair immediately after the operation of the line is completed. For example, in a coke oven, carbon adheres to the surface of the furnace wall during long-term operation, and in order to repair the surface to which carbon has adhered, it is necessary to remove carbon before performing thermal spray repair. Also, JP-A-57-166489
In the case of irradiating only the flame in advance and keeping the wall surface of the deposition furnace at a sufficiently high temperature, as in Japanese Patent Publication, it is not effective in a place where the inlet is small and the heat in the container is sufficient by one-time preheating, such as in a converter. However, in a place with a large inlet such as a coke oven, it is impossible to maintain a sufficiently high temperature by preheating once. It may be difficult to secure the initial temperature of the furnace wall because it may involve work such as carbon removal.

On the other hand, in the method of using a preheating / heat-retaining burner in addition to the spraying burner and the technique of repairing the spraying while observing the furnace wall condition using a TV camera, the spraying equipment, especially the lance that enters the furnace Also, there is a problem that the work becomes more difficult because the burner is heavy or complicated.

[0009]

The present invention is directed to particles of one or more easily oxidizable metals that burn to form a refractory oxide in a flame of a combustible gas and a combustion-supporting gas, and one or more particles. In the technique of hot spray repair of the furnace wall using a mixed refractory material consisting of refractory oxide particles as a spray material, by the presence of a molten solidification layer between the furnace wall surface and the spray repair layer,
This is a technology that improves the adhesion of the thermal spray repair layer to the furnace wall.

That is, according to the present invention, the thermal spray repair layer for the furnace wall is characterized in that the thermal spray repair layer applied to the furnace wall surface of the kiln has a melt-solidified layer in the repair layer near the interface with the base furnace wall. I will provide a. Further, according to the present invention, the content of the easily oxidizable metal particle oxide in the one-third thickness of the base-furnace wall side of the thermal spraying repair layer applied to the furnace wall surface is within the remaining two-third thickness. The thermal spray repair layer of the furnace wall is characterized in that the content of the easily oxidizable metal particle oxide is 2.5 times or more.

The first method for obtaining the above-mentioned sprayed repair layer is to spray a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles onto the furnace wall surface to form the sprayed repair layer on the furnace wall surface. In the method of repairing a furnace wall to be formed, the oxidizable metal particles in the mixed refractory material used for forming the sprayed repair layer having a thickness within one-third of the total thickness of the sprayed repair layer on the base furnace wall side Make the blending ratio 2.5 times or more the blending ratio of the easily oxidizable metal particles in the mixed refractory material used for forming the thermal spraying repair layer having a thickness of two-thirds of the surface of the total thermal spraying repair layer. Is characterized by. However, in this case, when the thickness within 1/3 of the substrate furnace wall side is less than 2 mm, this is set to 2 mm.

A second method for obtaining the above-mentioned thermal spray repair layer is to spray a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles onto the furnace wall surface to form the thermal spray repair layer on the furnace wall surface. In the method of repairing the furnace wall to be formed, the temperature of the base furnace wall surface immediately before thermal spraying is heated to a temperature equal to or higher than the melting point of the easily oxidizable metal particles. As a third method for obtaining the thermal spray repair layer, the temperature of the thermal spray flame for forming the thermal spray repair layer having a thickness within one third of the total thermal spray repair layer thickness on the base furnace wall side is The temperature is preferably 200 ° C. or more higher than the temperature of the thermal spray flame forming the remaining thermal spray repair layer. Furthermore, a combination of the first method and the second method, a combination of the first method and the third method.
It is preferable to combine these means and repair the furnace wall according to the actual situation, such as a combination of the above methods or a combination of the above first, second, and third methods.

Further, the present invention is intended to easily form a sound thermal sprayed repair layer which is sound and solidified while preheating and heat-retaining the furnace wall of the base portion. As a specific method, in the flame of the flammable gas and the combustion-supporting gas, in the method of hot repairing the furnace furnace refractory wall by supplying the repair material, in the flame to be continuously irradiated, the repair material In this method, the damaged portion of the refractory is repaired by flame spraying by supplying the repairing material in a pulsed state at regular intervals.

As a fourth method for obtaining the above-mentioned sprayed repair layer, a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles is sprayed onto the furnace wall surface of the kiln and sprayed onto the furnace wall surface. A furnace wall repair method for forming a repair layer, characterized in that the mixed refractory material is supplied into the flame in a pulsed manner while maintaining the irradiation of the flame. Pulse-like means to supply intermittently every short time.

Further, as a fifth method for obtaining the above-mentioned sprayed repair layer, a mixed refractory material composed of easily oxidizable metal particles and refractory oxide particles is sprayed onto the furnace wall surface of the kiln furnace to spray it onto the furnace wall surface. In a method of repairing a furnace wall for forming a sprayed repair layer, flame irradiation is maintained when a sprayed repair layer having a thickness within one-third of the base furnace wall side of the total spray repair layer thickness is formed. At the same time, there is provided a furnace wall repairing method, characterized in that the mixed refractory material is supplied in a pulsed manner into a flame.

As a sixth method for obtaining the above-mentioned sprayed repair layer, a mixed refractory material consisting of metal particles and refractory particles is supported on the furnace wall surface together with a mixed gas of an inert gas and a combustible gas or a combustible gas. A method for repairing a furnace wall, in which a sprayed repair layer is formed on a furnace wall surface by being sprayed in a flammable gas flow, and a spraying thickness within one third of the base furnace wall side of the total sprayed repair layer thickness is provided. Form a repair layer. When the maximum particle diameter Dmax (μm) of the refractory particles at the time of thermal spraying is defined as the distance x (mm) from the injection tip of the mixed refractory material to the substrate furnace wall, it is specified by the formula (1).

Dmax = k × (Tf−Tm) × x (1) Here, k is a coefficient depending on the material of the refractory material, and is 4.5 × 10 ⁻⁴ , Al ₂ O with respect to the SiO ₂ -based oxide. It is a coefficient of 7.0 × 10 ⁻⁴ with respect to the ₃ type oxide. Further, Tf is the temperature (° C.) of the flame portion at the time of thermal spray formation, and Tm is the melting point (° C.) of the refractory oxide.

As a seventh method for obtaining the above-mentioned sprayed repair layer, a mixed refractory material composed of easily oxidizable metal particles and refractory oxide particles is mixed on the furnace wall surface with a mixed gas of an inert gas and a combustible gas. Alternatively, in a method for repairing a furnace wall in which a sprayed repair layer is formed on the furnace wall surface by injecting it into a stream of a combustion-supporting gas together with a combustible gas, a one-third of the total thickness of the sprayed repair layer on the side of the base furnace wall The nozzle moving speed at the time of thermal spraying for forming the thermal spraying repair layer having a thickness of 0.5 m / min or less is characterized.

An eighth method for obtaining the above-mentioned thermal spray repair layer is as follows: At the time of thermal spraying for forming a thermal spray repair layer having a thickness within one third of the total thermal spray repair layer thickness on the furnace wall side of the base substrate. (Oxygen / propane) volume ratio is higher than the (oxygen / propane) volume ratio for forming the remaining thermal spray repair layer by 2.5 or more and 10.0 or less. Further, it is preferable that the above first to eighth methods combine these means to repair the furnace wall according to the actual situation.

In the present invention, the refractory particles are
Silica, alumina, mullite, chamotte, zircon,
It is sufficient to contain one or more of any one of zirconia, spinel, magnesia, maggro, etc., but it is particularly effective when silica stone is used. Above k except for silica
The value of can be obtained as the relationship between the melting point, density and specific heat of each substance.

[0021]

According to the present invention, since the durability of the thermal spray repair layer on the furnace wall is governed by the interface between the base furnace wall brick and the thermal spray repair layer, the thermal spray is improved by strengthening the interface. The adhesiveness, that is, the durability of the repair layer can be improved. In order to form a molten solidified layer near the interface on the side of the thermal spray repair layer at the interface between the base furnace wall and the thermal spray repair layer, it is necessary to melt the first thermal spray repair layer of the furnace wall brick immediately after the start of thermal spray repair. Good.

The method for forming the melt-solidified layer will be described in detail below. (A) Increasing the blending ratio of easily oxidizable metal particles in the thermal spray repair material forming the thermal spray repair layer near the furnace wall side. As one method to sufficiently melt the fusion repair layer, paying attention to the heat of combustion of easily oxidizable metal particles blended in the thermal spray repair material, attempting to sufficiently melt the thermal spray repair layer, and conducting various experiments. I went. Since the thermal spray flame is generated by the combustion of combustible gas and supporting gas, in order to pay sufficient attention to the thermal spray flame to sufficiently melt the thermal spray repair layer, the thickness of the total thermal spray repair layer is The mixing ratio of the easily oxidizable metal particles in the mixed refractory material used for forming the thermal spray repair layer within 1/3 of the side,
It has been found that the mixing ratio of the oxidizable metal particles in the mixed refractory material used in the two-third thickness portion on the surface side of the thermal spray repair layer should be 2.5 times or more.

Here, the mixing ratio of the easily oxidizable metal particles in the mixed refractory material used for forming the thermal spraying repair layer having a thickness within 1/3 of the thickness of all the thermal spraying repair layers on the base furnace wall side is The reason for defining as 2.5 times or more the compounding ratio of the easily oxidizable metal particles in the mixed refractory material used for the repair layer having a thickness of 2/3 on the surface side of the thermal spray repair layer is as follows. . The reason for using a material with a high compounding ratio of easily oxidizable metal particles in a mixed refractory material within one-third of the total thermal spray repair layer on the furnace wall side is that if it is greater than one-third The melting of the entire material progresses too much and the solidification is delayed, the sprayed repair layer remains in a molten state, and it flows down including the solidified portion.As a result, the smoothness of the surface of the sprayed repair layer cannot be obtained, and the furnace Not suitable for wall repair. That is, if the surface is highly uneven, for example, in a coke oven, the coke will be stuck or clogged, which is not preferable.

In forming the total sprayed repair layer within one-third of the furnace wall side, by increasing the compounding ratio of the easily oxidizable metal particles in the molten repair material, oxidation of the easily oxidizable metal particles causes large combustion. Heat is obtained, which makes the refractory material more likely to melt. As a result, a molten solidified layer is formed near the interface of the furnace wall on the side of the thermal spray repair layer. The oxidizable metal particles are not particularly specified, but the maximum particle size is preferably 0.3 mm or less. This makes it possible to further improve the adhesiveness and adhesiveness of the sprayed repaired portion.

The refractory particles are not particularly specified, but the maximum particle size is preferably 0.5 mm or less. This is because it is possible to further improve the adhesion and adhesiveness of the thermal spray repair section. (B) The temperature of the base furnace wall immediately before the melting and repairing is set higher than the melting point of the oxidizable metal compounded in the thermal spray material.

Another method of forming the melt-solidified layer is to make the temperature of the base furnace wall immediately before the melt repair higher than the melting point of the easily oxidizable metal compounded in the thermal spray material. When the temperature of the base furnace wall is low, heat absorption from the thermal spray material to the furnace wall brick is large immediately after the start of thermal spray repair of the furnace wall brick, and the melting of the thermal spray repair layer becomes insufficient. Therefore, it is necessary to raise the temperature of the furnace wall just before the thermal spray repair, but as a result of various experiments, it was found that the temperature of the furnace wall should be higher than the melting point of the easily oxidizable metal particles.

For example, when the material of the furnace wall of the coke oven is silica brick, the easily oxidizable metal mixed in the thermal spray material is metallic silicon, and its melting point is 1400 ° C. 14
When metallic silicon adheres to a base furnace wall brick at a temperature of 00 ° C. or higher, the metallic silicon melts and is liquefied, and the furnace wall brick gets wet. Silica powder of refractory oxide particles adheres to the wet part. At the same time, since the metallic silicon is oxidized, combustion heat is obtained from the metallic silicon, and the silica powder adhered is melted by the heat. As a result, the vicinity of the interface on the thermal spray repair layer side is melted and solidified.

As described above, by setting the temperature of the furnace wall immediately before the thermal spray repair to be equal to or higher than the melting point of the easily oxidizable metal particles, the molten solidified layer can be formed in the vicinity of the interface of the thermal spray repair layer side of the furnace wall. When aluminum particles are used as the easily oxidizable metal particles when the furnace wall material is an alumina refractory material, the furnace wall temperature may be set to 670 ° C. or higher, which is the melting point of aluminum. (C) Increasing the flame temperature for forming the sprayed repair layer near the furnace wall side.

Of the total thickness of the thermal spray repair layer, the thermal spray flame temperature for forming the thermal spray repair layer within one third of the base furnace wall side is lower than the flame temperature for forming the remaining thermal spray repair layer. It was found that a strong melt-solidified layer can be formed at a high temperature of 200 ° C. or higher. Specified here that the temperature of the spray flame for forming the spray repair layer within 1/3 of the inner spray wall side of the total spray repair layer is 200 ° C or more higher than the flame temperature for forming the remaining spray repair layer. The reason is as follows.

It is one-third that the thermal spray repair layer for raising the thermal spray flame temperature to within 1/3 of the entire thermal spray repair layer on the furnace wall side.
If it is attempted to make it larger, melting of the refractory material proceeds too much and solidification is delayed, the sprayed repair layer remains in a molten state, and flows down including the solidified portion. As a result, the smoothness of the surface of the sprayed repair layer cannot be obtained, which is not suitable for repairing the furnace wall. In other words, if the surface irregularities are severe, for example, in a coke oven, there will be push-stops / stop-stops, which is not possible.

By making the temperature of the spray flame for forming the entire sprayed repair layer within 1/3 of the furnace wall side higher than the temperature for formation of the remaining sprayed repair layer by 200 ° C. or more, oxidation of easily oxidizable particles is caused. Greater heat of combustion is obtained, which makes the refractory material more likely to melt. As a result, a good melted and solidified layer is formed near the interface with the furnace wall on the side of the thermal spray repair layer. (D) Decrease the nozzle moving speed at the time of forming the thermal spray repair layer near the furnace wall side.

Of the total thermal spray repair layer thickness, 3 on the base furnace wall side
It has been found that a strong melted and solidified layer can be formed by forming a thermal spraying repair layer having a thickness of less than a fraction of 1 and setting the nozzle moving speed during thermal spraying to 0.5 mm / min or less. Here, it was specified that the nozzle moving speed during spraying should be 0.5 m / min or less for forming a sprayed repaired layer having a thickness within 1/3 of the total thickness of the sprayed repaired layer on the base furnace wall side. Is due to the following reasons.

The reason why the thermal spraying repair layer for reducing the nozzle moving speed is set to be within one-third of the total thermal spraying repair layer on the furnace wall side is that when it is attempted to make it larger than one-third, the flame irradiates the refractory material. Becomes longer, the refractory material melts too much and solidification is delayed, the sprayed repair layer remains in a molten state, and flows down including the solidified portion. As a result, the smoothness of the surface of the sprayed repair layer cannot be obtained, which is not suitable for repairing the furnace wall.
That is, if the surface irregularities are severe, for example, in a coke oven, it will stop and will be clogged, which is not possible.

By setting the nozzle moving speed at the time of thermal spraying to 0.5 m / min or less in the formation of the total thermal spray repair layer within 1/3 of the furnace wall side, the time for the flame to irradiate the substrate furnace wall becomes long The temperature of the furnace wall rises sufficiently to melt the refractory material,
It becomes easy to stick. As a result, a good melted and solidified layer is formed in the vicinity of the interface with the furnace wall on the side of the thermal spray repair layer. When the nozzle moving speed exceeds 0.5 mm / min, the temperature of the furnace wall of the substrate is insufficiently increased, and it becomes difficult to form a good melt-solidified layer. (E) To increase the (oxygen / propane) volume ratio during thermal spraying when forming the thermal spray repair layer near the furnace wall side.

Of the total thickness of the sprayed repair layer, 3 on the base furnace wall side
The volume ratio of the combustion-supporting gas / combustible gas at the time of spraying, that is, (oxygen / propane) volume ratio for forming the thermal spraying repair layer having a thickness within 1 / /
It has been found that a strong melt-solidified layer can be formed by increasing the volume ratio of propane to 2.5 or more.
The (oxygen / propane) volume ratio is defined as the volume ratio of oxygen gas and propane gas ejected per unit time in the standard state.

Here, of the total sprayed layer repair thickness, the (oxygen / propane) volume ratio at the time of spraying that forms a sprayed repair layer having a thickness within one-third of the substrate furnace wall side is the remaining spray repair layer. The oxygen content is defined to be 2.5 or more higher than the (oxygen / propane) volume ratio for the formation of the following reasons for the following reasons. Spraying mixed refractory material consisting of particles of one or more easily oxidizable metals that burn to form refractory oxides and one or more refractory oxide particles in the flame of flammable gas and supporting gas As a material, in a technique of spraying into a stream of combustion-supporting gas together with a mixed gas of an inert gas and a flammable gas or a flammable gas to hot-spray and repair the furnace wall, (oxygen / propane) volume during spraying Increasing the ratio can form a dense thermal spray repair layer, but reduces the material yield. this is,
Increasing the (oxygen / propane) volume ratio means increasing the amount of oxygen when the combustion-supporting gas is oxygen, which promotes the combustion of easily oxidizable metal particles in the thermal spray material and the combustion heat at that time. As a result, the refractory oxide particles attached to the furnace wall are melted. On the other hand, for example, since there is excess oxygen that does not burn with propane, which is a flammable gas, the flame temperature drops, and refractory oxide particles do not melt during flight in the flame, which causes The number of refractory oxide particles deposited will be reduced. As a result, a dense thermal spray repair layer can be formed, but the material yield is reduced. As a result of performing the experiment in consideration of the above, the (oxygen / propane) volume ratio at the time of thermal spraying, which forms a thermal spraying repair layer having a thickness within one-third of the base furnace wall side in the total thickness of the thermal spray repair layer From the (oxygen / propane) volume ratio for forming the remaining thermal spray repair layer.
By increasing the ratio to 5 or more and 10.0 or less, the decrease in material yield can be suppressed, and a good melt-solidified layer can be formed in the vicinity of the interface with the furnace wall on the side of the thermal spray repair layer.

The (flame-supporting gas / combustible gas) ratio for forming the remaining thermal spray repair layer may be the volume ratio used in ordinary flame spraying. If it is less than 2.5, it is difficult to obtain a sufficient molten and solidified layer, and if it exceeds 10.0, the combustion-supporting gas becomes excessive and the temperature of the flame is apt to decrease. (F) Combining the above means.

By arbitrarily combining the above means (a), (b), (c), (d) and (e), a preferable melt-solidified layer can be easily obtained due to their synergistic effect. According to the present invention, a method for supplying a repairing material into a flame in a pulsed state to install burners for preheating and heat retention before and after the spraying burner to perform spraying repair while maintaining the furnace wall at a high temperature It is possible to easily form a sound thermal spray repair layer equivalent to

A flame formed by supplying a combustible gas and a combustion supporting gas required for the main thermal spray repair to the thermal spray repair burner,
It is possible to secure the initial high temperature of the furnace wall by heating the damaged part furnace wall with a flame in advance before spraying the repair material. Then, if the repair material is supplied to the burner for thermal spray repair in the flame formed by the supply of the combustible gas and the combustion supporting gas required for the main thermal spray repair, the initial high temperature of the furnace wall is secured. The material for use adheres to the damaged portion of the furnace wall in a molten or anti-molten state.

Then, the repair portion is further heated by irradiating only the flame to maintain the high temperature of the furnace wall, and the unmelted material among the repair materials is melted,
A sound thermal spray repair layer, preferably a melt-solidified layer, can be formed near the interface of the furnace wall. By repeatedly performing the above-described repair method in a pulsed manner over a wide range of the furnace wall repair section, a sound spray repair layer can be easily formed.
The method of supplying the thermal spray repair material (mixed refractory material) in a pulsed manner according to the present invention is sufficient if it is used within 1/3 of the substrate furnace wall side, and thereafter, a normal flame spray repair method may be used.

The method for forming the melt-solidified layer will be described in detail below. A nozzle for injecting a mixed refractory material with a maximum particle size Dmax (μm) of refractory particles during thermal spraying, which forms a thermal spray repair layer having a thickness within 1/3 of the total thickness of the thermal spray repair layer The distance from the tip to the base furnace wall is x (m
It was found that, when m), a strong melt-solidified layer can be formed by defining by the formula (1).

Here, the maximum particle diameter Dmax of the refractory oxide particles at the time of thermal spraying, which forms the thermal spray repair layer having a thickness within 1/3 of the total thickness of the thermal spray repair layer, is defined as follows. The distance from the nozzle tip where the mixed refractory material is jetted to the base furnace wall is x
In this case, the reason defined by the equation (1) is as follows. The inventors investigated various experimental results and heat balances, and found that the particle diameter D (μm) when the refractory particles were silica stones was a distance x (mm) and the center of the sprayed layer formation surface during spraying formation. It was found that the refractory material melts up to D ≦ 4.5 × 10 ⁻⁴ (Tf-1650) × x with respect to the flame temperature (° C.) of the part. That is, if the refractory particles have the maximum particle diameter D, all the refractory particles will be melted by the distance x, and this distance x is the distance from the injection tip of the mixed refractory material to the base furnace wall. If so, all the refractory particles are melted in the flame and the molten refractory material arrives at the base furnace wall. As a result, a good melted and solidified layer is formed in the vicinity of the interface with the furnace wall on the side of the thermal spray repair layer.

With respect to the above findings, when the refractory particles alumina and magnesia were similarly examined, the maximum particle diameter Dmax was x, Tf and Tm, and Dmax = k × (Tf-Tm) × x. For example, it was found that all the refractory particles melt in the flame and the molten refractory material arrives at the base furnace wall, forming a good molten solidified layer near the interface with the furnace wall on the thermal spray repair layer side. It was Here, the coefficient k is the melting point T of the refractory particles.
(K), density ρ (g / cm ³ ), specific heat C (J / g · K)
And k = f (T, ρ, C). Also,
Tm is the melting point T (° C.) of the refractory particles.

As a concrete value of k, such as silica stone
SiO_Two 4.5 × 10 for refractories ^-FourAluminum refractory
In case of 7.0 × 10^-FourIt is. 3 minutes on the furnace wall side of the entire thermal spray repair layer
Of refractory oxide particles during thermal spraying in the formation within 1
Large particle size Dmax from the injection tip of mixed refractory material to the base furnace
When the distance to the wall is x, it should be specified by equation (1).
With, the refractory particles are completely melted in the flame and the base furnace
Molten refractory material arrives at the walls. As a result, thermal spray repair
A good melt-solidified layer is formed near the interface between the furnace wall and the layer side.
You.

[0045]

【Example】

(Example-1) Silica-like refractory powder (average particle size 150
μm) and metallic silicon powder (average particle size 82 μm) were mixed at different weight ratios, and a silica-based substrate brick installed in an experimental furnace with an atmospheric temperature set at 750 ° C. Flame spraying was performed to form a sprayed repair layer, and the adhesion state between the substrate brick and the sprayed repair layer was investigated. A schematic view of the thermal spray repair layer is shown in FIG. Thermal spray repair layers 2 and 3 were formed on the surface of the substrate brick 1. In FIG. 1, the thicknesses of the thermal spray repair layer 2 adjacent to the base brick 1 and the thermal spray repair layer 3 on the surface side of the thermal spray repair layer are b and c, respectively.
The layer C was used, and various thermal spraying conditions were changed, and tests were conducted.
The total thickness was a. Substrate brick 1 was exposed to only a flame immediately before thermal spraying to raise its surface temperature.

Table 1 shows the spraying conditions. Further, Table 2 shows the thermal spraying conditions, the surface temperature of the substrate brick 1 and the adhesion state of the thermal spray repair layer. The adhesion state of the thermal spray repair layer was evaluated by observation with a stereoscopic microscope. No. in Table 2 1-3, the mixing ratio of the metallic silicon particles in the mixed refractory material used when forming the thermal spray repair layer of 2 mm or more on the substrate brick side of the total thermal spray repair layer is less than one third. For the blending ratio of metallic silicon particles in the mixed refractory material used when forming the thermal spray repair layer,
By setting the ratio to 2.5 times or more, the As described in No. 7, by heating the surface temperature of the substrate brick immediately before thermal spraying to 1400 ° C. or higher, which is the melting point of metallic silicon,
o. The thermal spray flame temperature for forming the thermal spray repair layer that is 2 mm or more and one third or less of the base brick side of the total thermal spray repair layer as shown in 9, 10 is 200 or more than the thermal spray flame temperature for forming the thermal spray repair layer. By making the temperature higher than or equal to ℃, it was possible to obtain a sprayed repair layer having excellent adhesiveness. Furthermore, by combining the above methods, No. 13
The adhesiveness of the thermal spray repair layer was further improved as shown in Table 1.

As is clear from Table 2, by using the present invention, a sprayed repair layer having excellent adhesion to the substrate brick and a smooth surface was obtained. All of the thermal spray repair layers in contact with the substrate bricks were melt-solidified layers that were once solidified after melting.

[0048]

[Table 1]

[0049]

[Table 2]

Example 2 A substrate brick (silica brick) having a surface temperature of about 600 ° C., which was previously installed in an experimental furnace, was filled with propane gas of 12.5 Nm as a combustible gas.
³ / h and oxygen gas as a combustion-supporting gas is 125 Nm ³
/ H to form a flame, silica stone powder (average particle size 165μ
m) and metallic silicon powder (average particle size 82 μm) 85: 1
Using the repair material mixed at a compounding ratio of 5, a spraying repair experiment was carried out at a spraying speed of 70 kg / h. In addition, as the evaluation items, the porosity, residual metal ratio, and material yield of the sprayed repair layer were measured.

Table 3 shows examples and comparative examples. In the examples, the porosity of the thermal spray repair layer is low by supplying the repair material in a pulsed state, sufficient metal is burned without residual metal in the thermal spray repair layer, and the material yield is also high, Moreover, if the preheating / heat holding time is longer than the material supply time, a more sound sprayed layer is formed, and the effect of supplying the repair material in a pulsed state to the flame was confirmed.

[0052]

[Table 3]

Example 3 Silica-based refractory powder (average particle size 165 μm) and metallic silicon powder (average particle size 105 μm)
m) and a thermal spray repair material mixed in different weight ratios, and flame sprayed on a silica-based substrate brick installed in an experimental furnace where the atmospheric temperature is set to 750 ° C. to form a thermal spray layer. The adhesion situation between the thermal sprayed repair layer and
A schematic view of the thermal spray repair layer is shown in FIG. Thermal spray repair layers 2 and 3 were formed on the surface of the substrate brick 1. In FIG. 1, the thicknesses of the thermal spray repair layer 2 adjacent to the base brick 1 and the thermal spray repair layer 3 on the surface side of the thermal spray repair layer are b and c, respectively, and these are referred to as B layer and C layer, and the thermal spray conditions are various. The test was carried out with changes. Further, the total thickness is a.

Table 5 shows the spraying conditions. Further, Table 5 shows the thermal spraying conditions and the adhesion state of the thermal spray maintenance layer. The adhesion of the thermal spray repair layer was evaluated by observation with a stereomicroscope. No. in Table 2 When forming a thermal spray repair layer of 2 mm or more on the base brick side of the total thermal spray layer, such as 1 and 2, the thickness within 1/3 of the total thermal spray repair thickness on the furnace wall side of the substrate Further, by setting the lance moving speed at the time of thermal spraying formed by the thermal spraying repair layer of 0.5 m / min or less, 6, 7, the volume ratio of (oxygen / propane) at the time of thermal spraying to form the thermal spraying repair layer having a thickness of 2 mm or more and one third or less of the base furnace wall side out of the total thermal spray repair layer It was possible to obtain a thermal spray repair layer having excellent adhesiveness by increasing the volume ratio of (oxygen / propane) by 2.5 or more. Furthermore, by combining the above methods, No. As in No. 10, the adhesiveness of the thermal spray repair layer was further improved.

As is clear from Table 5, by using the present invention, a thermal spray repair layer having excellent adhesion to the substrate brick and a smooth surface was obtained. All of the thermal spray repair layers in contact with the substrate bricks were melt-solidified layers that were once melted and then solidified.

[0056]

[Table 4]

[0057]

[Table 5]

Example 4 Experiment in which the atmospheric temperature was set to 750 ° C. by using a thermal spraying repair material in which silica stone powder and metallic silicon powder (average particle size 105 μm) were mixed at different weight ratios. Flame-spraying was performed on the silica-based substrate brick installed in the furnace to form a sprayed layer, and the adhesion state between the substrate brick and the sprayed repair layer was investigated. A schematic view of the thermal spray repair layer is shown in FIG. Thermal spray repair layers 2 and 3 were formed on the surface of the substrate brick 1. In FIG. 1, the thicknesses of the thermal spray repair layer 2 adjacent to the base brick 1 and the thermal spray repair layer 3 on the surface side of the thermal spray repair layer are b and c, respectively, and these are referred to as B layer and C layer, and the thermal spray conditions are various. The test was carried out with changes. Further, the total thickness is a. A test was also conducted when the base brick was made of alumina.

Table 6 shows the spraying conditions. Table 7 shows the conditions for thermal spraying and the adhesion of the thermal spray repair layer. The adhesion state of the thermal spray repair layer was evaluated by observation with a stereoscopic microscope. No. in Table 7 Among the total thermal sprayed layers 1, 2, and 6, of the total thermal sprayed repair thickness when forming the thermal sprayed repair layer of 2 mm or more and one third or less on the side of the substrate brick,
The maximum particle diameter Dmax (μ of the refractory oxide particles at the time of thermal spraying formed by the thermal spraying repair layer having a thickness within 1/3 of the base furnace wall side)
m), where x (mm) is the distance from the injection tip of the mixed refractory material to the base furnace wall, Dmax = k × (Tf−
By satisfying the relationship of Tm) × x, it was possible to obtain a thermal spray repair layer having excellent adhesiveness.

As is clear from Table 7, by using the present invention, a thermal spray repair layer having excellent adhesion to the substrate brick and having a smooth surface was obtained. All of the thermal spray repair layers in contact with the substrate bricks were melt-solidified layers that were once melted and then solidified.

[0061]

[Table 6]

[0062]

[Table 7]

[0063]

EFFECTS OF THE INVENTION By adopting the thermal spray repair layer and the method thereof according to the present invention for hot spray repair of a furnace wall, it is possible to melt and solidify the vicinity of the interface on the side of the thermal spray repair layer at the interface between the furnace wall and the thermal spray repair layer. It is possible to improve the durability of the thermal spray repair layer.

[Brief description of drawings]

FIG. 1 is a schematic view showing a thermal spray repair layer.

[Explanation of symbols]

 1 Base Brick 2 Melt Solidified Layer (Sprayed Repair Layer) 3 Sprayed Repair Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Shimizu 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd. Chiba Works (72) Inventor Nozomi Tamura Kawasaki-cho, Chuo-ku, Chiba Chiba Chiba Steel Works, Ltd.

Claims (12)

[Claims] 1. A thermal spray repair layer applied to the furnace wall surface of a kiln,
A thermal spray repair layer for a furnace wall, which has a melted and solidified layer in the repair layer near the interface with the base furnace wall. 2. The content ratio of the oxidizable metal particle oxide in the one-third thickness of the base metal wall side of the thermal spraying repair layer applied to the furnace wall surface of the kiln is the remaining two-thirds thickness. A thermal spray repair layer for the furnace wall, which is 2.5 times or more the content of the easily oxidizable metal particle oxide therein. 3. A furnace wall repair method for forming a sprayed repair layer on a furnace wall surface by spraying a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles on the furnace wall surface of a furnace. The ratio of the oxidizable metal particles in the mixed refractory material used for forming the thermal spray repair layer having a thickness within one-third of the thickness of the thermal spray repair layer on the side of the base furnace wall is defined as the total thermal spray repair layer thickness. The method for repairing a furnace wall is characterized in that the mixing ratio of the oxidizable metal particles in the mixed refractory material used for forming the two-third-thickness thermal spray repair layer on the surface side is 2.5 times or more. 4. A method for repairing a furnace wall in which a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles is sprayed on the furnace wall surface of a kiln furnace to form a sprayed repair layer on the furnace wall surface. A method for repairing a furnace wall, characterized in that the temperature of the immediately preceding furnace wall surface is heated to a temperature not lower than the melting point of the easily oxidizable metal particles. 5. A method for repairing a furnace wall in which a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles is sprayed on the furnace wall surface of a kiln furnace to form a sprayed repair layer on the furnace wall surface. The thermal spray flame temperature for forming the thermal spray repair layer having a thickness within one third of the thickness of the thermal spray repair layer on the base furnace wall side is set to 200 ° C. or more higher than the thermal spray flame temperature for forming the remaining thermal spray repair layer. A method for repairing a furnace wall, which comprises: 6. The method for repairing a furnace wall according to claim 3, further comprising heating a furnace wall surface temperature immediately before thermal spraying to a temperature equal to or higher than a melting point of the easily oxidizable metal particles. 7. The thermal spray flame temperature for forming a thermal spray repair layer having a thickness within one-third of the base furnace wall side of the total thermal spray repair layer thickness is the thermal spray flame temperature for forming the remaining thermal spray repair layer. 4. The temperature is set to be 200 ° C. or more higher than that.
Or the method of repairing the furnace wall according to the item 6. 8. A method of repairing a furnace wall in which a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles is sprayed on the furnace wall surface of a kiln furnace to form a sprayed repair layer on the furnace wall surface. A method for repairing a furnace wall, characterized in that the mixed refractory material is supplied into the flame in a pulsed manner while maintaining the irradiation. 9. A furnace wall repair method for spraying a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles on a furnace wall surface of a kiln furnace to form a sprayed repair layer on the furnace wall surface. When forming a thermal spraying repair layer having a thickness within one-third of the thickness of the thermal spraying repair layer on the side of the base furnace wall, while supplying the flame, the mixed refractory material is supplied in a pulsed manner. A method for repairing a furnace wall, which comprises: 10. A method of repairing a furnace wall in which a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles is sprayed on the furnace wall surface of a kiln furnace to form a sprayed repair layer on the furnace wall surface,
The maximum particle size of the refractory oxide particles forming the thermal spraying repair layer having a thickness within 1/3 of the total thickness of the thermal spraying repair layer on the side of the base furnace wall is Dmax (μm) or less, which is represented by the formula (1). The method for repairing a furnace wall is characterized by the following. Dmax = k × (Tf−Tm) × X (1) where X: distance from the injection position of the mixed refractory material to the wall surface of the base furnace (mm) k: coefficient depending on the type of refractory oxide SiO ₂ system For oxides, k = 4.5 × 10 ^{−4 For} Al ₂ O ₃ -based oxides, k = 7.0 × 10 ⁻⁴ Tf: Flame part temperature (° C.) Tm: Refractory oxide melting point (℃) 11. A method for repairing a furnace wall in which a mixed refractory material consisting of easily oxidizable metal particles and refractory oxide particles is sprayed on the furnace wall surface of a kiln furnace to form a sprayed repair layer on the furnace wall surface,
The moving speed of the thermal spray nozzle is 0.5 m / min or less when forming the thermal spray repair layer having a thickness within 1/3 of the total thickness of the thermal spray repair layer on the base furnace wall side. Method of repairing furnace wall. 12. A flame-retardant material comprising a combustible gas or a mixed gas of a combustible gas and an inert gas, on a furnace wall surface of a kiln, which is composed of easily oxidizable metal particles and refractory oxide particles. A method of repairing a furnace wall in which a thermal spraying repair layer is formed on a furnace wall surface by being sprayed in a gas stream, the method comprising: The volume ratio of the combustion-supporting gas / flammable gas when forming the repair layer is 2.5 or more and 10 or more with respect to the volume ratio of the combustion-supporting gas / flammable gas when forming the remaining thermal spray repair layer. A method for repairing a furnace wall, which is characterized by increasing the value to 0.0 or less.