On the basis of comparing all kinds of related retrofitting solutions

the optimization solution solving such problems as high flue gas temperature at SCR inlet and insufficient drying capacity of the pulverizing system was put forward.This scheme arranges parallel flue pass at the economizer inlet and adds tubular air preheater low-pressure economizer inside the parallel flue pass

which can take use of the flue gas heat to heat the primary air.Moreover

analysis such as thermodynamic calculation

drying capacity calculation for the pulverizing system

air preheater arrange calculation and low-pressure economizer calculation were performed

which verifies this solution is safe and economic.Application of this solution in a lignite coal fired boiler shows that

the standard coal consumption rate for power generation reduced by 4.14g/(kW·h)

which achieved the expected goal.The total static investment of this retrofit scheme is 1.536.9×107yuan

which can be returned within 4.3years.