Abstract: The invention relates to a method and apparatus for cooling the exhaust gases of a molten stage furnace. The method relates to furnace structures in which the shaft (3) is vertical and the exhaust gases are passed through an outlet in the furnace roof to the cooling equipment without recovering heat from the exhaust gases through the wall portions above the furnace. The exhaust gases are cooled in two stages first indirectly by a circulating mass cooler (1) and then further in a waste heat recovery boiler. In the apparatus according to the invention, the vertical shaft section above the furnace is connected to a circulating mass cooler which is connected to a waste heat recovery boiler arranged, e.g., next to the furnace and/or the shaft.

Abstract: A fluidized bed gas cooler assembly includes a fluidized bed gas cooler with a metal inlet duct for directing hot process or flue gases into the cooler as fluidizing gas. In order to remove deposits which form on the duct inner surface a cooling fluid is passed into and then out of contact with the outer surface of the inlet duct so that the cooling fluid increases in temperature (but does not change phase) and so that deposits which form on the inlet duct interior surface become brittle and readily disengageable. The deposits are disengaged at different times by pulsation of the cooling fluid (especially where the inlet duct is a metal spiral tube), effecting pulsation of the temperature of the cooling fluid, or subjecting an enclosure surrounding the duct or the exterior surface of the duct itself to a sudden mechanical force.