After steam drum is boosted to 2.5MPa, contact central control room to start regular blow-down work, adjust continuous blow-down according to boiler water quality, pay attention to continuous blow-down expansion vessel pressure, prevent pressure-surpassing, meanwhile, require operation staff in central control room completely open each blow-down valves in upper header box for one minute, start work according to sequence, there shall be no missing, decide blow-down times according to actual turbidity