At present

more and more power plants began to burn lignite to ease the negative situation of coal supply tension and the rising price of coal.But high moisture content in lignite may lead to insufficient coal drying output and affect the safe operation of coal pulverizing system.Capacity expansion revamp on nozzle ring of coal pulverizer in sub-critical 2×600MW unit boilers of Inner Mongolia Jing Long Power Plant was performed.By changing the air preheater turning

enlarging the primary air warehouse area and adding the radial soft seal

the hot primary air temperature at outlet of the air preheater was increased by about 30℃and the air leakage rate in air preheater dropped significantly.Moreover

the drying and grinding capacity of the coal mill was dramatically enlarged

the resistance in primary air system decreased.On the premise of satisfying the requirements of firing lignite with large proportion

the power consumption of fan facility system and danger of primary air warehouse stalling were decreased.