Effect of Slurry Coating on the Resistance of Thermal Insulation Insert in Blast Furnace Air Tuyere

Air tuyeres account for 30% of all heat losses in a blast furnace. One of the methods for lining a tuyere from the air passage side is to use a thermal insulation insert. However, certain defects of the insert on the working surface of the air passage along with thermal stresses generated therein may lead to its premature failure during operation. This paper discusses applying a slurry coating to the inner surface of the insert to prevent its premature cracking and improve performance. The effect of a slurry-coated thermal insulation insert on gas dynamics and heat transfer inside a blast furnace air tuyere was studied, and simulation of the above processes was performed. It was shown that applying a slurry coating to the lower portion of the thermal insulation insert is most beneficial for increasing the heat flux and raising the air-blast temperature at the tuyere outlet, while applying the coating to the entire inner surface of the insert helps improving its resistance, which has been confirmed experimentally.