Experimental investigation on design features and operation characteristics of two 660 MW unit W-flame boilers manufactured by Dongfang Boiler Group Co.

Ltd.was conducted.The biggest innovation during design of above two boilers lies in that the upper layer over fire air is added in the combustion system

and staged air injection method was adopted to reduce the NOxemission.The operation and performance experimental results showed that

under full load condition

the boiler efficiency was 91.42%

higher than the guarantee value 91.30%;all the main steam flow/temperature/pressure and reheat steam temperature/pressure reached the design value

and both the amount of first and second stage desuperheating water for superheaters were below the design value;the NOxemission concentration was far lower than the required value 900 mg/m3.