Kiln preheater towers provide heat transfer from hot gases to kiln feed material. The counterflow of gases and material takes place in cyclones, referred to as stages, in the preheat tower. As material flows from the top to bottom of the tower, it is exposed to increasingly higher temperatures as it is prepared to enter the kiln. Temperatures range from 300°C to 1300°C, with excursion reaching much higher. These high temperatures, as well as abrasion, alkali attack, and buildup, must all be considered when making refractory decisions.
Refractories installed in preheat towers are subject to severe abrasion. Material buildup on the walls can cause plugging and stoppage as well as severe alkali attack. Any refractory installed in the lower portion of the tower should have an anti-buildup component and good abrasion resistance. In the upper part of the preheat tower, the materials are generally “lower tech” monolithics that conserve energy and have good abrasion resistance. HarbisonWalker International’s product lines include the VERSAFLOW®, VERSAGUN®, VERSA-TECH, and THOR® families. Our THOR® family of products offers a complete line of low-cement, fused zirconia-mullite monolithics. Installation options include traditional vibration casting, pump casting, shotcreting, and conventional wet gunning. All THOR® products exhibit high hot strengths, abrasion resistance, resistance to alkali attack, and superior thermal shock resistance.