Overhigh flue gas temperature at SCR inlet and insufficient drying capacity of pulverizing system in lignite boilers:reason analysis and countermeasures

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.