Effect of raw coal grindability on the uniformity of pulverized blended coal for entrained-flow pulverized coal gasification

Two pulverized coals taken from an entrained-flow pulverized coal gasification unit at different operating periods were adopted as the experimental materials, which were divided into two groups based on the partical size to investigate the effect of raw coal grindability on the uniformity of pulverized blended coal. The coal quality and the ash character of the subsamples were analyzed as well. The results show that the grindability of raw coal has a great influence on the partical size distribution and the uniformity of pulverized blended coal, and the partical size distribution of blended coal is mainly depended on the raw coal with a smaller grindability index. The smaller the raw coal's grindability index, the larger the particle size of the pulverized blended coal. It is therefore concluded that the pulverized blended coal made from similar grindability raw coals is more uniform. On the other hand, different grindabilities of raw coals lead to nonuniformity and segregation of the pulverized blended coal and induce an accumulation of hard coal in the large particles, which will cause the reactivity of the pulverized blended coal decrease.