The service life of refractory materials is mainly affected by erosion conditions in addition to the performance of refractory materials. When the same refractory material is used in different parts, the erosion conditions are different, so the use effect is also different. For example, when the β-corundum fused refractory material is used for the side wall of the upper structure of the horizontal flame pool furnace, it is severely eroded and damaged near the feeding port where the temperature is not high, but the erosion is very slight when it is used at a high temperature far from the feeding port. It is not as imagined that the higher the temperature, the more severe the erosion. This is mainly due to the fact that erosion is not determined by the temperature alone. In the above case, the refractory material is attacked by different kinds and different amounts of chemical attacking agents in addition to the temperature factor.
.jpg)
.jpg)
There are four main types of chemical attack.
①Erosion caused by the reaction between molten glass and refractory material
This erosion is represented by pool wall tiles in contact with the glass. The most important glass is soda lime silica glass. General bottle glass and flat glass belong to this category. This glass is mainly composed of SO2, with a content of about 70%, Na2O content of about 15%, CaO content of about 10%, and a small amount of Al2O3 and MgO. In order to improve the properties of glass, oxides such as K2O, L2O, BaO, PbO can be introduced based on soda lime silica glass. Although there are many kinds of these glasses, they can be simplified as SO2 content, alkali metal oxide (Na2O+K2O+L2O) content and alkaline earth metal oxide content (CaO+MgO+BaO) to consider. As long as the content of the above three oxides is basically the same, the chemical attack on the refractory material is basically the same. However, the chemical attack of borosilicate glass on refractory materials is different from that of soda-lime-silica glass. In particular, low-alkali or alkali-free borosilicate glass has a high content of acid oxides and a high melting temperature. Therefore, special refractory materials are used.
The chemical attack of glass on the refractory, if not accompanied by physical attack, proceeds very slowly. The superstructure near the feed port is chemically attacked by batch dust. The composition of the batch dust here is basically the same as that of the glass liquid. That is to say, the chemical attack of the refractory material here is basically the same as that of the pool wall brick. But the wall tiles suffered much more damage than the superstructure. The reason for this difference is mainly due to different physical erosion conditions. In addition to the chemical erosion of glass, the pool wall bricks are also subject to physical erosion by the scouring action of the glass flow. The scouring of the liquid flow continuously washes away the products of chemical attack, so that the glass liquid can continuously chemically attack the fresh surface of the refractory material. As a result of the combined action of these two types of erosion, the wall tiles of the pool are damaged rapidly. However, the superstructure is only attacked by batch dust of the same composition as the glass, and there is no physical attack by the liquid flow. Therefore, the products of chemical erosion remain on the surface of the refractory material, which plays a protective role and prevents further erosion of the refractory material by the batch dust. It can be seen that the damage degree of chemical erosion has a great relationship with the physical erosion.
.jpg)
②Erosion caused by chemical reaction between glass batch dust and refractory material.
This chemical attack occurs mainly in the melting pool superstructure and regenerator of the pool furnace. In different parts, the dust of batch materials 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 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 glass batch, the amount of dust has a great relationship with the density, particle size and feeding method of the raw material. Adding water to the ingredients, pressing cakes or making balls can greatly reduce the amount of dust in the ingredients.
③Chemical erosion caused by the reaction of glass batch volatiles and refractories
The volatiles of glass and batch materials exist in the upper space of the pool furnace and the middle of the regenerator, and chemically attack the refractory materials in these parts. The components of volatiles are mainly alkali metal oxide compounds and boron compounds, as well as fluoride, chloride and sulfur compounds. In addition to chemical reactions with refractory materials in the gas phase state, these volatiles will condense into liquid phase and chemically react with refractory materials when the temperature is low. The sodium compound is at 1400°C. will condense. These condensed liquids penetrate into the pores of the refractory material through infiltration and diffusion. Especially when the superstructure masonry has cracks and joints that are not filled with mud, it can cause great damage to the refractory material.
.jpg)
④Chemical erosion caused by the chemical reaction of fuel ash and combustion products with refractory materials
When burning heavy oil and natural gas, ash basically does not exist, and although V₂O5 and NO are seriously eroded to refractory materials, the content of heavy oil is generally very small, which has little effect on the production of pool furnaces. The sulfur in heavy oil and producer gas generates SO₂ during combustion, and reacts with R₂O in the volatile components to form sodium sulfite. The chemical reaction between sodium sulfite and refractory materials is strong, and this influencing factor should be considered in the glass production process.
Zhengzhou Shennan Refractory Co.,Ltd are professional in producing high quality refractory bricks ,any demands,please don't hesitate contact with me.
 |
+86-15238007351 |
 |
+86-371-86039318 |
 |
annie@snrefractory.com |
 |
www.snrefractory.com |
