Coal slurries in mixed liquid fuels: rheology and ignition characteristics

In the presence of surfactant, coal/No.2 oil+ethanol, slurries containing water exhibited dramatic reduction in Bingham yield stress and plastic viscosity. The observed rheological behavior was explained in terms of coal particle network formation by water bridging mechanism. Lowering of interfacial tension between water and suspension medium in the presence of surfactant was attributed to be responsible for the reduced yield stress and plastic viscosity. In the low heating rate experiments, ignition behavior of slurries containing up to 20 wt.% of water was not appreciably altered. It appears that water vaporizes prior to the ignition/combustion stage, thereby not influencing the overall ignition behavior.