Low grade coal accounts for half of all coal resources in the world, and super-high-moisture
coal with a moisture content exceeding 50% is one such kind. When such super-high-moisture coal
is applied to conventional USC boilers, the shortage of mill drying capacity and the decline of
ignitability and combustibility caused by the decrease of oxygen concentration in burner zones and
the increase of the moisture content of coal particles are the main concerns. In this research,
grinding tests and combustion tests using super-high-moisture coal were carried out by Mitsubishi
Hitachi Power Systems, Ltd. (MHPS), and the stable grinding conditions for preventing particle
adhesion in mills under high humid atmosphere, as well as stable combustion under low oxygen
concentration in primary gas, were verified. These results enabled the utilization of low grade and
super-high-moisture coal in conventional USC boilers.
