Abstract
In our previous paper, a new measurement method for coal thermoplasticity, “permeation distance method”, was devised. Permeation distance of thermally plastic coal into glass beads layer adjacently placed on the coal sample was measured as a unique caking property. The maximum permeation distance measured is roughly correlated with Gieseler fluidity, however large deviation is observed especially in high fluidity coals. Moreover, it was revealed that high MF coal having longer maximum permeation distance forms thinner pore-wall structures in coke and that coke strength deteriorated when the coal blend included longer maximum permeation distance coal. Therefore, technique for reducing the adverse effects of long maximum permeation distance coal on coke strength is necessary so as to utilize the coal more efficiently.
In this paper, influence of grain size mainly of high MF coal on permeation distance and coke strength were investigated for clarifying possibility of controlling permeation distance. As a result, measured maximum permeation distance became shorter with decreasing coal size. Moreover, the coke strength deterioration caused by long maximum permeation distance coal in coal blend was suppressed as the size of the long maximum permeation distance coal became smaller. Consequently, designs and control techniques of coal size were proposed for more effective utilization of long maximum permeation distance coal.
