Abstract: hen the chimney of a thermal power plant is corroded seriously, the unit and the wet desulphurization system will can not operate normally. During isolated repairing of the original chimney, to install a temporary chimney is needed. The safe switchover of the original chimney and the temporary chimney becomes major concern. The key technical link in safe switchover of the original chimney and the temporary chimney of Huadian International Zouxian Power Plant was introduced, and the problems encountered in switchover process were summarized, which can be used as reference for relevant technicians.

Key words: desulphurization system, original chimney, temporary chimney, blocking board, safe switchover