Abstract: In order to solve the problems of scaling, blockage and corrosion of the GGH of limestonegypsum wet desulphurization system, a new type chemical clean technology for GGH was proposed, in which it is not needed to dismantle the heat transfer elements. The neutral chemical cleaning agent will be sprayed on the GGH surfaces directly. The cleaning period of the new technology is shorter. The scaleremoving efficiency of the new technology is not less than 95%. The neutral chemical cleaning agent does not corrode the heat transfer elements and devices. The waste water of chemical cleaning will be treated in the power plant waste water system and discharged as qualified waste water. The operation rate of the desulphurization system, the GGH of which had been cleaned by the new technology, was increased by more than 0.5%. The SO2 emission was decreased, and favorable social effect was obtained. According to the estimation, to clean a 600MW unit one time in a overhaul period can generate the economic benefit ￥1,000,000~2,000,000 in one year.

Key words: gas-gas heater (GGH), scaling, blockage, new type chemical clean technology, application