This paper studies the effects of wet sludge amount on operational parameters of coal-fired boiler in which the sludge is dried by extracting flue gas

by taking a 300 MW unit coal-fired unit as the research object. On the basis of energy conservation equation

thermal balance and thermal check calculation is carried out to investigate the change rules of flue gas extraction ratio

thermal efficiency

coal consumption

flue gas temperature

spray water flux and gas flow under conditions of BMCR

75%THA

50%THA and 30%THA

when the flue gas is extracted from low temperature superheater outlet to heat the sludge. The results show that

blending sludge will cause deterioration of the boiler's main parameters. The parameters variation increases when the boiler load decreases and the amount of wet sludge increases. Comprehensively considering the engineering cost and the influences on boiler parameters and environmental facilities

the percentage of wet sludge blending should be controlled below 8% under full load condition.