Types of chemical erosion on refractories in glass kilns

1.?Chemical erosion?caused by the reaction between molten glass and refractory materials

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This erosion is typified by pool wall tiles in contact with molten glass. The most important glass is soda lime silica glass. General bottle glass and flat glass belong to this category. The main component of this glass is SO2, the content is about 70%, the content of Na20 is about 15%, the content of Ca0 is about 10%, and there are a small amount of Al2O3 and MgO.

The performance of glass, based on soda-lime-silicate glass, can introduce oxides such as K2O, L2O, BaO, PbO, etc. Although there are many types of these glasses, they can be simplified to SO2 content, alkali metal oxide (Na2O+K2O+L2O) content and alkaline earth metal oxide content (CaO+MgO+BaO) to consider. As long as the contents of the above three oxides are basically the same, the chemical erosion?on refractory materials is also basically the same. However, the chemical erosion?of borosilicate glass on refractory materials is different from that of soda-lime-silica glass, especially low-alkali or non-alkali borosilicate glass, which has a high content of acid oxides and a high melting temperature. Therefore, special refractory materials should be used.

The chemical erosion?of glass on refractory materials proceeds very slowly if there is no physical erosion?at the same time. The superstructure near the feed opening is chemically erosioned by batch dust. Here, the composition of the batch dust is basically the same as that of the molten glass. That is to say, the refractory material here is basically the same as the chemical erosion?of the pool wall brick. But the damage to the pool wall bricks was much more severe than that of the superstructure. The reason for this difference is mainly due to the different physical erosion conditions. In addition to the chemical erosion of the glass, the pool wall tiles are also physically eroded by the scour of the glass liquid flow. The scouring of the liquid flow continuously washes away the products of chemical erosion, so that the glass liquid can continuously chemically erosion?the fresh surface of the refractory material. As a result of the joint action of these two types of erosion, the pool wall tiles are damaged very quickly. However, the upper structure is only eroded by the batch dust with the same composition as the glass, and there is no physical erosion of the liquid flow here, so the products of chemical erosion remain on the surface of the refractory material, which plays a protective role and prevents the batch dust from affecting Further erosion of refractory materials, it can be seen that the degree of damage of chemical erosion has a great relationship with physical erosion.

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2.?Chemical erosion caused by chemical reaction between glass batch material dust and refractory materials

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This chemical erosion?mainly occurs in the upper structure of the melting pool of the pool furnace and the regenerator. In different parts, the batch dust is also different. The composition of the batch dust near the feeding port is basically the same as that of the glass. Due to the high density of silica sand particles, the farther away from the feeding port, the lower the SO2 content in the batch dust. The amount of batch dust is related to many factors. For the same kind of glass batch material, the dust amount has a great relationship with the raw material density, particle size and feeding method. Adding water to batch materials, pressing cakes or making balls can greatly reduce the amount of dust in batch materials.

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3.?Chemical erosion caused by the reaction of glass batch volatiles and refractory materials

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The volatiles of glass and batch materials exist in the upper space of the pool furnace and the middle of the regenerator, and chemically erosion?the refractory materials in these parts. Volatile components are mainly alkali metal oxide compounds and boron compounds, as well as fluoride, chloride and sulfur compounds. In addition to chemically reacting with refractory materials in the gas phase state, these volatiles will also condense into liquid phase and chemically react with refractory materials when the temperature is low. Among them, sodium compounds will condense at 1400 °C. Diffusion penetrates into the pores of the refractory material. Especially when the superstructure masonry has cracks and joints that are not filled with mud, it will cause great damage to the refractory material.

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4.?Chemical erosion caused by the chemical reaction between fuel ash and combustion products and refractory materials

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When burning heavy oil and natural gas, ash basically does not exist. Although V2O5 and NO seriously corrode refractory materials, they generally contain very little in heavy oil and have little effect on the production of pool furnaces. Sulfur in heavy oil and producer gas generates SO2 during combustion, and reacts with R2O in volatile components to form sodium sulfite.?