JP6882587B1 - Dry spray material for firing pots - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a physical impact and an erosion reaction from an object in a furnace in a dry spray material for a firing furnace, and improve the durability. SOLUTION: This is a dry spray material for a firing furnace having a furnace wall temperature of 1400 ° C. or less, and one or more of powdered alkali silicate and alkali phosphate is 0.2% by mass or more in total. 10% by mass or less, 0.3% by mass or more and 5% by mass or less of boron carbide, mainly alumina raw material, silica raw material, alumina-silica raw material, silicon carbide raw material, magnesia raw material, magnesia-calcia raw material, and these Contains one or more selected refractory raw materials after use, including at least one of the raw materials of the above, and in 100% by mass of the total amount of the dry spray material, a SiO2 component derived from a raw material having a particle size of less than 75 μm is contained. Contains 7% by mass or more. [Selection diagram] None

Description

The present invention is a dry spray material for firing furnaces such as incinerators, fluidized bed furnaces, industrial waste kiln treatment furnaces, circulating fluidized bed (CFB) boiler furnaces, cement manufacturing equipment furnaces, gasification melting furnaces, stoker furnaces, etc. Regarding.

Conventionally, a spraying material to which alumina cement is applied as a binder is known (see, for example, Patent Document 1). Patent Document 1 describes that the application can be applied to an incinerator in addition to a blast furnace gutter, a torpedo wagon, and the like.

Japanese Patent No. 4263917

In a firing furnace that heat-treats (fires and incinerates) the contents of the furnace like an incinerator, the sprayed construction body that becomes the furnace wall receives physical impact and erosion reaction from the contents of the furnace that are flowing in the furnace. There is a problem that it is easy.

The present inventors examined a dry spraying material to which alumina cement was applied as a binder as a spraying material for a firing furnace, but the sprayed body was severely damaged and could not be put into practical use.

An object to be solved by the present invention is to suppress a physical impact and an erosion reaction from an internal object in a dry spray material for a firing furnace to improve the durability.

According to one aspect of the present invention, a dry spray material for the next firing furnace is provided.
A dry spray material for firing furnaces with a furnace wall temperature of 1400 ° C or less.
A total of 0.2% by mass or more and 10% by mass or less of one or more of powdered alkali silicate and alkali phosphate, 0.3% by mass or more and 5% by mass or less of boron carbide, mainly in the balance. One or more selected from post-use refractory raw materials including alumina raw materials, silica raw materials, alumina-silica raw materials, silicon carbide raw materials, magnesia raw materials, magnesia-calcia raw materials, and at least one of these raw materials. Contains,
A dry spraying material for a firing furnace, which contains 7% by mass or more _{of a SiO 2} component derived from a raw material having a particle size of less than 75 μm in 100% by mass of the total amount of the dry spraying material.

According to the present invention, although details will be described later, a _{glass film is formed mainly by the reaction of a SiO 2} component derived from a raw material having a particle size of less than 75 μm with an alkali silicate or an alkali phosphate, and further, a surface of boron carbide and a glass film are formed. By reacting with and to produce borosilicate glass, the bonds between the raw material particles (boron carbide and other fire-resistant raw materials) become stronger, and boron carbide with high hardness remains, so that from the inside of the furnace. It can suppress physical impact and erosion reaction and improve durability.

The dry spray material of the present invention is a dry spray material for a firing furnace having a furnace wall temperature of 1400 ° C. or less, and contains one or more of powdered alkali silicate and alkali phosphate in total. Containing 2% by mass or more and 10% by mass or less, and 0.3% by mass or more and 5% by mass or less of boron carbide, 7 _{SiO 2 components derived from a raw material having a particle size of less than 75 μm are contained in 100% by mass of the total amount of the dry spray material.} It is a characteristic constituent requirement that it is contained in an amount of mass% or more. Hereinafter, the action and effect of this characteristic constituent requirement will be described.

In the temperature range of the furnace wall temperature of 1400 ° C. or lower, the SiO ₂ component mainly derived from a raw material having a particle size of less than 75 μm reacts with an alkali component derived from an alkali silicate or an alkali phosphate to form a glass film. Further, the surface of boron carbide reacts with the glass coating to form borosilicate glass, and other fire-resistant raw materials and boron carbide are firmly adhered to each other. Since the reaction between the boron carbide and the glass coating is only on the surface of the boron carbide particles, there is residual boron carbide that does not react in the sprayed body. Therefore, the bonds between the particles (boron carbide and other fire-resistant raw materials) are strengthened, and boron carbide having high hardness remains, which contributes to the improvement of wear resistance of the sprayed body. As a result, it is possible to reduce damage to the sprayed construction body due to physical impact from the inside of the furnace and erosion reaction.
In the temperature range exceeding 1400 ° C., the glass film melts, so that the above effect cannot be obtained. Therefore, the use of the dry spray material of the present invention is limited to a firing furnace having a furnace wall temperature of 1400 ° C. or lower. The furnace wall temperature is preferably 1200 ° C. or lower. The lower limit of the furnace wall temperature is not particularly limited and is determined by the lower limit of the firing temperature of the firing furnace, but it is preferably about 800 ° C. or higher from the viewpoint of surely obtaining the effect of forming the glass film.

If the total content of one or more of the alkali silicate and the alkali phosphate is less than 0.2% by mass, the effect of forming the glass film cannot be obtained. On the other hand, if it exceeds 10% by mass, a low melt is produced and the corrosion resistance is lowered. The total content of one or more of the alkali silicate and the alkali phosphate is preferably 1% by mass or more and 5% by mass or less.
Here, the alkali silicate typically comprises one or more of sodium silicate, lithium silicate, potassium silicate and calcium silicate. The alkali phosphate is typically composed of one or more of sodium phosphate, lithium phosphate, potassium phosphate and calcium phosphate.

When the content of boron carbide is less than 0.3% by mass, the amount of boron carbide remaining is reduced and the above-mentioned effect of improving wear resistance cannot be obtained. If the content of boron carbide is more than 5% by mass, low melt is generated and the corrosion resistance is lowered, and the bonds between the particles (boron carbonized and other fire resistant raw materials) become too strong and the spalling resistance is improved. descend. There is also the problem of higher costs. The content of boron carbide is preferably 0.5% by mass or more and 3% by mass or less.
Further, the particle size composition of boron carbide is preferably 50% by mass or more when the particle size is less than 0.5 mm. When the particle size of less than 0.5 mm is 50% by mass or more, boron carbide is evenly dispersed in the sprayed body, so that the wear resistance can be further improved.

As described above, the dry spray material of the present invention contains powdered alkali silicate and / or alkali phosphate and boron carbide, the rest of which are mainly alumina raw materials, silica raw materials, alumina-silica raw materials, and silicon carbide. It comprises one or more refractory raw materials selected from post-use refractory raw materials, including raw materials, magnesia raw materials, magnesia-silica raw materials, and at least one of these raw materials. The above-mentioned fire-resistant raw material mentioned as the balance is "mainly" of the balance, and the balance includes fire-resistant raw materials other than the above-mentioned fire-resistant raw materials, binders other than alkali silicate and alkali phosphate (alumina cement, etc.), and hardening. A regulator (sulfate, slaked lime, etc.), an explosion inhibitor (organic fiber, etc.) and the like may be appropriately contained. However, if a large amount of alumina cement is contained, a large amount of hydrate is generated, which tends to cause explosion during drying. Therefore, the content of alumina cement should be 10% by mass or less (including 0). It is preferably 5% by mass or less (including 0), and more preferably.

_{When the content of the SiO 2} component derived from a raw material having a particle size of less than 75 μm is less than 7% by mass in the total amount of 100% by mass of such a dry spray material, the effect of forming the above-mentioned glass film and the effect of improving wear resistance are improved. Cannot be obtained. _{The upper limit of the content of the SiO 2} component derived from the raw material having a particle size of less than 75 μm is not particularly limited from the viewpoint of forming a glass film, but it should be approximately 40% by mass or less in consideration of the balance of the properties of the sprayed body. Can be done. _{The preferred range of the SiO 2} component content derived from the raw material having a particle size of less than 75 μm is 15% by mass or more and 35% by mass or less.
_{Here, the SiO 2} component derived from a raw material having a particle size of less than 75 μm includes a fire-resistant raw material (boron dioxide, an alumina raw material, an alumina-silica raw material, a siliceous raw material, etc.) and other raw materials (curing modifier, etc.) having a particle size of less than 75 μm. SiO ₂ component as the main component or impurity components contained in, and a total amount of SiO ₂ component as the main component or impurity components contained in the alkali silicate and phosphoric acid alkali having a particle size of less than 75 [mu] m, which is dry Coatings It can be specified by the raw material composition of.

The dry spraying material for a firing pot of the present invention is sprayed onto a firing furnace by a dry spraying method. As is well known, the dry spraying construction method is a construction method in which water is added to a dry powder spraying material (dry spraying material) at the tip of the spray nozzle and sprayed. The amount of added water may be appropriately determined so that the spray softness of the dry spray material is within an appropriate range, but is approximately 10% by mass or more and 15% by mass or less when applied externally to 100% by mass of the total amount of the dry spray material. Is.

The dry spray materials of each example shown in Table 1 were evaluated for wear resistance, corrosion resistance and spalling resistance, and a comprehensive evaluation was performed based on these evaluation results. Further, Example 8 and Comparative Example 1 were subjected to an actual reactor test. In Table 1, "alkali silicate" is one or more of sodium silicate, lithium silicate, potassium silicate and calcium silicate, and "alkali phosphate" is sodium phosphate and phosphoric acid. One or more of lithium, potassium phosphate and calcium phosphate.

The evaluation method and evaluation criteria for each evaluation item are as follows.
<Abrasion resistance>
The sample was kneaded with an amount of water assuming an appropriate spray softness, and the molded sample was fired at a firing temperature (see Table 1) assuming the furnace wall temperature of the firing furnace, and then the amount of wear was evaluated by sandblasting.
When the amount of wear was less than 10 cc, it was evaluated as 〇 (excellent), when it was 10 cc or more and less than 15 cc, it was evaluated as Δ (good), and when it was 15 cc or more, it was evaluated as × (defective).

<Corrosion resistance>
Knead with an amount of water assuming appropriate spray softness, shape into a pot shape, fire at a firing temperature (see Table 1) assuming the furnace wall temperature of the firing furnace, then add 30 g of erosion agent to the pot, and further, as described above. The erosion state was confirmed by heating for 12 hours at the firing temperature assuming the furnace wall temperature of. The erosion agent, CaO: 60 wt%, MgO: 10 _wt%, K 2 O: 10 _{wt%, P 2} O 5: Using 20 wt% of synthetic slag. The maximum erosion area of each example was measured, and a relative value was obtained with Example 3 as 100. The smaller the relative value, the better the corrosion resistance.
When the relative value is less than 100, it is evaluated as 〇 (excellent), when it is 100 or more and less than 120, it is evaluated as Δ (good), and when it is 120 or more, it is evaluated as × (bad).

<Spolling resistance>
Knead the sample with an amount of water assuming an appropriate spray softness, and repeat 10 times for 15 minutes and 15 minutes for air cooling in an atmosphere of firing temperature (see Table 1) assuming the furnace wall temperature of the firing furnace, and the degree of cracking. Evaluated by.
The case where there was no crack or the crack width was within 1 mm was evaluated as ◯ (excellent), the case where the crack width was more than 1 mm and 2 mm or less was evaluated as Δ (good), and the case where the crack width was more than 2 mm was evaluated as × (poor).

<Comprehensive evaluation>
When all the evaluations were ○, it was evaluated as 〇 (excellent), when there was no × and any one of them had Δ, it was evaluated as Δ (good), and when any one of them had ×, it was evaluated as × (poor).

<Actual reactor evaluation>
After using it as a furnace wall for a firing pot with a furnace wall temperature of 1200 ° C. for 2 months, the average value measured randomly at 10 locations shows that the remaining thickness is 90% or more of the original construction thickness. If it was less than%, it was evaluated as x (failed).

In Table 1, Examples 1 to 12 are dry spraying materials within the scope of the present invention. These comprehensive evaluations were 〇 (excellent) or Δ (good), and good evaluations were obtained in all of wear resistance, corrosion resistance, and spalling resistance. Among them, in Examples 8 to 11, the above-mentioned preferable contents of alkali silicate and alkali phosphate, content of boron carbide, particle size composition of boron carbide, and _{content of SiO 2 component derived from a raw material having a particle size of less than 75 μm are preferable.} It is a dry spray material within the range. The overall evaluation was 〇 (excellent), and a better evaluation was obtained as compared with the other examples.

Comparative Example 1 is an example in which the content of boron carbide is low, and the evaluation of wear resistance is x (poor).
On the other hand, Comparative Example 2 was an example in which the content of boron carbide was high, and the evaluation of corrosion resistance and spalling resistance was x (poor).

_{Comparative Example 3 is an example in which the content of the SiO 2} component derived from a raw material having a particle size of less than 75 μm is small, and the evaluation of wear resistance and corrosion resistance was × (defective).

Comparative Example 4 is an example in which the alkali silicate and the alkali phosphate are not contained, and the evaluation of wear resistance is x (poor).
On the other hand, Comparative Example 5 was an example in which the content of alkali silicate was high, and the evaluation of corrosion resistance was x (poor).

Comparative Example 6 is an example in which the firing temperature assuming the furnace wall temperature of the firing furnace is high, and the evaluation of corrosion resistance is × (defective).

Claims (3)

A dry spray material for firing furnaces with a furnace wall temperature of 1400 ° C or less.
A total of 0.2% by mass or more and 10% by mass or less of one or more of powdered alkali silicate and alkali phosphate, 0.3% by mass or more and 5% by mass or less of boron carbide, mainly in the balance. One or more selected from post-use refractory raw materials including alumina raw materials, silica raw materials, alumina-silica raw materials, silicon carbide raw materials, magnesia raw materials, magnesia-calcia raw materials, and at least one of these raw materials. Contains,
A dry spraying material for a firing furnace, which contains 7% by mass or more _{of a SiO 2} component derived from a raw material having a particle size of less than 75 μm in 100% by mass of the total amount of the dry spraying material. The total content of one or more of the alkali silicate and alkali phosphate is 1% by mass or more and 5% by mass or less, and the content of boron carbide is 0.5% by mass or more and 3% by mass or less. _{The dry spray material for a baking furnace according to claim 1, wherein the content of the SiO 2} component derived from a raw material having a particle size of less than 75 μm is 15% by mass or more and 35% by mass or less in the total amount of the dry spray material of 100% by mass. .. The dry spray material for a firing furnace according to claim 1 or 2, wherein the boron carbide having a particle size of less than 0.5 mm is 50% by mass or more.