Abstract: An exhaust gas containing sulfur trioxide is passed through a first heat exchanger which cools the gas to a temperature which is above the sulfur trioxide dewpoint, so that condensation of sulfur trioxide does not occur in the first heat exchanger, but below a material limit operating temperature of a second heat exchanger, which further cools the gas below the sulfur trioxide dewpoint, whereby the first heat exchanger is protected against corrosion and the second heat exchanger is protected against thermal damage.

Abstract: Flue gas is passed through a first heat exchanger, a wet scrubber, and a second heat exchanger. The first heat exchanger supplies heated liquid to the second heat exchanger to reheat the flue gas. The first heat exchanger comprises, and the second heat exchanger ideally comprises, a plurality of fluoroplastic-covered metal tubes extending through a fluoroplastic-lined gas passage.

Abstract: An exhaust gas containing sulfur trioxide is passed through a first heat exchanger which cools the gas to a temperature which is above the sulfur trioxide dewpoint, so that condensation of sulfur trioxide does not occur in the first heat exchanger, but below a material limit operating temperature of a second heat exchanger, which further cools the gas below the sulfur trioxide dewpoint, whereby the first heat exchanger is protected against corrosion and the second heat exchanger is protected against thermal damage.

Abstract: A water-condensing heat exchanger recovers heat from a hot flue gas, subjecting tubes of the heat exchanger to substantial thermal expansion and contraction, and corrosive constituents in the flue gas require that metal tube sheets be thoroughly insulated from the flue gas during operation in a water-condensing mode. The heat exchanger is constructed by heat-forming edge portions of holes in plastic sheets through holes in tube sheets, temporarily plugging the plastic-lined holes to limit diametrical reduction, and entering tubes through the plastic-lined holes sufficiently shortly after unplugging the holes that further diametrical reduction of the holes causes them to grip and fixedly locate the tubes relative to the tube sheets. The method of manufacture also concerns providing a fluroplastic coating, e.g., polytetrafluoroethylene, on the interior elements of the heat exchanger to inhibit corrosion thereof; such coatings are hydrophobic thus allowing falling condensate to be washed away easily.

Abstract: Exhaust gas treatment method and apparatus extract heat from an exhaust gas by operating in a water-condensing mode which allows more heat to be recovered, removes particulate matter and condensed acid from the exhaust gas, and washes heat exchange surfaces to keep them clean and wet to improve heat transfer. Systems for heating water, air and both water and air are disclosed. Methods of constructing and assembling improved heat exchangers are disclosed.

Abstract: Exhaust gas treatment method and apparatus extract heat from an exhaust gas by operating in a water-condensing mode which allows more heat to be recovered, removes particulate matter and condensed acid from the exhaust gas, and washes heat exchange surfaces to keep them clean and wet to improve heat transfer. Systems for heating water, air, and both water and air are disclosed. Methods of constructing and assembling improved heat exchangers are disclosed.

Abstract: Exhaust gas treatment method and apparatus extract heat from an exhaust gas by operating in a water-condensing mode which allows more heat to be recovered, removes particulate matter and condensed acid from the exhaust gas, and washes heat exchange surfaces to keep them clean and wet to improve heat transfer. Systems for heating water, air, and both water and air are disclosed. Methods of constructing and assembling improved heat exchangers are disclosed.