Study on Liquid-Coupled Indirect-Transfer type Non-Leakage Gas Gas Heat Exchanger.

The Ljungstroem rotary type Gas-Gas Heat Exchanger (GGH) has been used extensively as the gas reheater for wet-type desulfurization plants. However, it is difficult for this type to cope with the severe dust emission regulations, because of unavoidable dust leakage from the untreated high temperature gas side to the treated low-temperature gas side. To solve this problem, the liquid-coupled indirect-transfer type was selected as the non-leakage GGH, because of its complete separation between both gas side and excellent design flexibility. This non-leakage type GGH, however, still leaves two major technical problems to be solved. One is countermeasure to dust plugging on the heat transfer surface and the other is sulfuric acid corrosion caused by condensation of SO/sub 3/ and H/sub 2/O in flue gas at low temperature. Test results obtained in the pilot plant using simulated gas to explore the basic operation characteristics and above-mentioned two problems are presented. Consequently, this liquid-coupled indirect-transfer type GGH was found to be an excellent means to achieve an extremely low dust emission level, and its application to wet type desulfurization plants was made practical by solving those two major technical problems.