Heat exchangers for secondary heat recovery from glass plants

Abstract

This paper addresses heat recovery from the exhaust gases leaving the brick checkers regenerator of a soda lime glass furnace. The most desirable uses for the recovered heat are electricity generation and batch preheat. An industry survey indicated that heat exchanger fouling is a primary factor that inhibits use of such heat recovery. For electricity generation, one would use either a Rankine or a Brayton cycle. The former would use a finned-tube heat exchanger, and the latter would use a plate-and-fin exchanger. This paper discusses the fouling, corrosion and cleanability of such heat exchangers in the glass furnace exhaust. The composition of the gases entering the exchanger is described and the expected fouling mechanisms are discussed. It is concluded that these exchangers should be cleanable and not subject to excessive corrosion, provided they operate above the acid dewpoint. The use of MgO would further enhance the cleanability of the fouling deposit. The fluidized-bed heat exchanger is an interesting concept for batch preheat. If the concept can be successfully employed, it would be a “self cleaning” heat exchanger.