Abstract: The structure of the old-type single tube chinmney is unfit for the wet FGD flue emission in the coal-fired power plants with no GGH equipped and it needs modification. Based on the practice and study of the chimney leakage and corrosion prevention modification in over 40 thermal power plants using the wet desulphurization technology, and in consideration of the safety and reliability, convenience and adaptability of inspection and maintenance, the modification plan on leakage and corrosion prevention of the single tube chimneies in service is proposed This proposal is suitable for the wet FGD without GGH in China, in which the plan of a new exhaust inner cylinder with the titanium clad steel lining installed inside the concrete chimney is recommended rather than that of adding brick masonry lining or anti seepage and antisepsis layer on the inner surface of the original chimney.

Key words: thermal power plant, single tube chimney, wet desulfurization, antisepsis, chimney modification