Preheating Operation Of Glass Furnaces

Preheating is one of the key factors that influence the performance and service life of glass furnaces.
Traditionally, the glass furnace is preheated by first warm-up heating and then firing at 800-850℃. Firing at 800-850℃ is because of crystal transformation of silica refractory and fireclay refractory. According to the thermal expansion coefficient and temperature range of silica refractory and fireclay refractory, the temperature curve and firing temperature range are made.
During the warm-up heating, refractory materials in all parts of glass furnaces can expand uniformly. However, after fired at 800-850℃, within 850-1200℃, the temperature fluctuates and is difficult to control. The big temperature fluctuation can cause intense changes of refractory materials. Within 950-1200℃, the crystal transformation of refractory materials occurs and is accompanied by 6% volume shrinkage. Within this temperature range, it is important to consider fused cast AZS block, because the big temperature fluctuation may cause the cracking of fused cast AZS block.
As fused refractories have high density, good abrasion resistance, good high temperature mechanical properties and good corrosion resistance to glass liquid, so the fused cast AZS block has been the most widely used refractory in the glass industry.
With the development of the preheating technology and temperature controlling technology, the temperature has been increased to 1100-1150℃. Within this temperature range, the crystal transformation of the refractory materials has been completed. Since the temperatures before and after the preheating link up well, there is no big temperature fluctuation, so the cracking of fused cast AZS can be avoided.