Which type of refractory brick is better for variable diameter rotary kiln?
The advantage of the variable diameter rotary kiln is that the calcining diameter becomes larger, which is conducive to the complete combustion of the fuel. The smaller diameter during the preheating section can concentrate the heat more and save energy. The energy saving effect is about 20% more energy-saving than the diameter kiln. Compared with the diameter rotary kiln, the variable diameter rotary kiln with the same production capacity can also save the cost of lining refractory bricks. However, production is difficult and can only be implemented with high and extensive experience.
The material selection of refractory firebricks for variable diameter rotary kiln depends on the nature of the combustion products in the lining. Variable diameter rotary kilns are often used to burn white ash. Phosphate composite bricks are generally used, also called corundum mullite bricks, and some manufacturers call them special phosphate composite bricks. Refractory bricks for variable diameter rotary kilns include high alumina bricks and phosphate composite bricks. However, the diameter of cement rotary kilns varies less. If the diameter of the cement rotary kiln changes, choose magnesia-alumina spinel bricks or silica-molybdenum red bricks.
High alumina bricks are used in variable diameter kilns that burn ceramsite sand and calcium chlorate powder, but the density of high alumina bricks should be above 2.7 and the aluminum content should be above 72%. Generally, the actual use effect of high-alumina bricks with aluminum content between 55-70% is not ideal.
In foreign variable-diameter cement rotary kilns, there are also high-aluminum refractory bricks with an aluminum content of more than 80%, but the use effect is not very good. There are also anti-flaking high-alumina bricks, which are better than high-alumina bricks. Since zirconium is added to the raw material of anti-flaking high alumina bricks, the strength, load softening temperature and wear resistance are longer than that of high alumina bricks. However, there are also calcined mullite bricks. This kind of material has low porosity, good flexural resistance, strong corrosion resistance, and relatively high price. Few manufacturers opt for lining.
Regardless of the material refractory bricks are made from, size is very important. In addition, during the masonry process, it must be from small diameter to large diameter, from bottom to high, otherwise the masonry will not be tight and the service life will be affected.
