In order to meet the requirements of safe and efficient combustion of high volatile coal in a 360 MW unit lean coal-fired boiler

the ignition

burnout and slagging characteristics of the coal were studied on the basis of composition analysis and thermogravimetric experiment. Through the research on the fuel adaptabilities of main systems such as coal pulverizing system

combustion system

air and flue gas system

the transformation scheme was put forward

which is conducted with a ball mill using flue gas drying

exhaust-air and hot air composite powder feeding technology. The results are as follows:(1) the system equipment of the unit can be flexibly switched according to the coal quality

which significantly improves the fuel adaptability; (2) all systems of the unit operate safely under different conditions

and all operating parameters meet the design requirements; (3)the thermal efficiency of the boiler is more than 92 %

the NOx concentration at the furnace outlet is greatly reduced

and the requirement of stable combustion under 40 % load of the unit is realized. In a word

this technical transformation has achieved remarkable effect on safety

economic and environmental protection. And it also provides important theoretical and engineering significance for the technical application of high-volatile coal burning in large lean coal-fired boiler in China.