Abstract: The present invention is directed to a method for recovering heat from a gas stream contaminated with water vapor and an acid-forming moiety, said gas having an acid dew point ranging from about 200.degree. F. to 300.degree. F. and a water dew point ranging from about 90.20 F. to 150.degree. F. The inventive method comprises passing the gas stream through a heat exchange fitted with a plurality of generally-parallel tubes through which flow heat exchanging fluid counter-current to the flow of said gas stream in said heat exchanger. The heat exchanging fluid is at a temperature such that the exterior tube temperature is at or below both said dew points, or the temperature of the contaminated gas stream exiting the heat exchanger is at or below both said dew points. The tubes are formed from acid-resistant, resin-impregnated graphite and exhibit a smooth, washable exterior surface. The heat exchanger further is fitted with a pair of side apertured tube sheets through which said tubes penetrate.

Abstract: A glass tube heat exchanger including a sealing sleeve comprising at least one hydraulic sealing section, an intermediate sealing section and an interior sealing section is disclosed. The hydraulic sealing section has a triangular cross section including one obtuse angle formed by two legs, one of which extends radially outwardly from the longitudinal axis of the seal. The intermediate sealing section comprises a generally cylindrical shaped body and at least one, and preferably two, toroidal belts. The interior sealing section comprises a lip adapted to seal tightly against the glass tube and a flange adapted to seal against the tube sheet. Preferably, the interior sealing section is a mirror image of the hydraulic sealing section.