Applying selective catalytic reduction(SCR) flue gas denitration system in coal-fired boiler will increase the auxiliary power and reducing agent consumption

and increase the operation cost. To reduce the operation cost

this paper establishes an operation cost model for the boiler and SCR denitration system by using the parameters including the unit load

total coal feed rate

total air volume

primary air pressure

secondary air rate

over fire air rate and ammonia injection rate

on the basis of considering the operation cost of the SCR denitration system and fuel cost of the boiler. The particle swam optimization(PSO) algorithm is proposed to optimize the adjustable parameters such as the primary air pressure

secondary air rate

over fire air rate and the ammonia injection rate

thus the optimal values of each parameter under different conditions are obtained.Moreover

simulation experiments were carried out by using the operation data of a 1 000 MW thermal power plant

and the results show that

the established model has good prediction precision and strong generalization ability

the combined operation cost of the unit after optimization can be reduced by 3%～5%.