The experiment of depth peak-load regulation capacitity was carried out on once-through boiler of a supercritical 350 MW unit. In order to meet the constraints of boiler operation safety

economic

and environmental protection discharge

adjustment and optimization of the operational controllable factors were performed

such as the operation mode of coal mill

operating oxygen volume fraction

and air distribution mode. The minimum electric load of the unit was decreased to 40.3% from 50% at the rated load without any flexibility reformation of the boiler. The depth peak-load regulation capacity was improved sharply. At the lowest load

when the B

D and E coal mill were put into operation

in the operating mode that the coal mill output is distributed evenly

the oxygen volume fraction is 5.0%

the air-coal ratio is 2.4

the burner swing angle is 70%

and the splitter revolution is 35 Hz

the inlet flue gas temperature of SCR denitration system can reach about 295 ℃

the denitration system operates normally

the environmental emission parameters are qualified

and the boiler runs stably

economically and safely.