In the acid quench vessel, the most important consideration is protection of the vessel’s steel shell. The refractory selection will be contingent on acid resistance, thermal-cycling resistance, and temperature limitations of the refractory lining and corrosion protection linings. Many of the acid-resistant coatings that are applied to steel support vessels have limited service temperatures, requiring thermally protective layers of acid-resistant refractory in the vessel. A water quench is employed to reduce gas temperatures, and consequently there is a possibility of thermal shock.
Vitreous or amorphous silica refractories, such as ON-LINE® THERMAX® G, VERSAFLOW® THERMAX® PLUS, and NOVACON® S, will resist corrosion by most acids (hydrofluoric acid being the major exception) and have exceptionally good thermal-cycling resistance. In cases where temperatures are expected to routinely exceed 2000°F (1093°C), high-purity, shock-resistant products such as the TUFLINE® family should be considered instead of silica-based refractories.