Abstract: Abstract:The larger air leakage rate of the rotary air preheater is difficulty troubling many large power generation enterprises, and it influences on unit economic operation seriously. Using a new air leakage control technology —— the gap selfcompensating air leakage control system, the Harbin Xinglong Boiler Company Limited implemented the air preheater seal reformation of unit No.3 in Ezhou Power Generation Company limited of Hubei Energy Group during the unit overhaul period. After reformation, under unit full load and variable load conditions, the air leakage rate remained within 4%～5% for long term, and the unit economic operation was ensured.

Key words: Keywords:air preheater, seal reformation, gap selfcompensating air leakage control system, effect, benefit