High temperature flue gases from industrial plants are a potential reservoir of useful energy. However, these gases are very corrosive and cause severe degradation of heat exchange equipment used to recover the energy. The proposed SBIR project builds on previous work and utilizes a shallow bed recuperator as the basic element of the heat exchanger. The bed is to be metallic, made of materials such as carbon steel, austenitic steel, Monel 400, and Inconel 617. The underside of the bed will be coated with a ceramic material. This ceramic layer will serve as the thermal skin of the bed plate. The concept of a thermal skin is well established for heat exchanger tubesheets. It is well known that the ligament temperature in a tubesheet is essentially constant throughout its thickness except for a thin layer (i.e., a thin skin) on the shellside surface where nearly all of the temperature rise occurs. This skin is quite thin and is a source of sharp incremental stress in the tubesheet, but it cannot produce bowing of the tubesheet. The bed plate will be water cooled, so that the bulk metal temperature will be maintained in the range of 550 degrees Fahrenheit. This temperature is low enough to ensure sufficient material strength and resistance to corrosion.
