Abstract: The second air flow of the power plant boiler is about 70% of boiler total air flow. Therefore, the secondary air flow must be measured accurately to obtain good adjustment quality of draft air and boiler automation. The original secondary air flow measurement device of No.8 unit of Guangzhou Hengyun Power Plant was unable to meet the measurement and control requirement, and it had been replaced by FLII type air flow measurement device with soot selfcleaning and antiblockage function at the unit overhaul. Then accurate measurement of secondary air flow was realized, and draft air and boiler automation were well put into operation, and the maintenance became easy.

Key words: draft air automation, FL type air flow measurement device, soot self-cleaning and anti-blockage