Abstract: The quality indexes of the Huaibeiproduced long flame coal and the quality indexes of the coal commonly used in power plants are almost the same; and the Huaibeiproduced long flame coal has good combustion economic efficiency. However, in practical use, if the Huaibei long flame coal is blended by too large ratio, then the explosion accident of the mill may happen easily. The pulverizing characteristics of the coal, the particle size distribution of the blended pulverized coal, the particle size segregation of the blended pulverized coal and the exhalation characteristics of the volatile matter of the Huaibei long flame coal were researched; and comparing with commonly used coal, it was found that the Huaibei long flame coal has not exclusive obvious explosion fatalness. According to the heat balance calculation and analysis of the mill, it was obtained that the basic reason of the higher explosion fatalness of the long flame coal is its lower water content, which causes the recirculating air of the mill to increase. Combining with the lower CO exhalation temperature of the coal and the fineness segregation of the blended coal powder and other factors, at the initial stage of mixed process of recirculating air and hightemperature air, more fine particles of pulverized Lulingproduced coal may enter into local hightemperature zone, and large amount of CO will exhale; so the explosion probability of the mill will increase. Two methods were proposed: one of them is to reduce the ratio of the long flame coal in blended coal, the other is to open the cold air gate of the mill; and practice shows that the two methods are effective.


Key words: middle storage type ball mill, explosion, long flame coal, CO exhalation temperature, recirculating air