Plastic behaviour of coal under rapid-heating high-temperature conditions

Abstract The plastic behaviour of a bituminous coal was determined under conditions pertinent to modern high-temperature coal conversion processes, using a specially developed fast-response plastometer. The instrument determines the torque required for constant rotation of a thin disc embedded within a thin layer of coal heated between two parallel metal plates. Heating rates, final temperatures and sample residence times at final temperature can be separately selected and controlled over the ranges 40–800 K s −1 , 600–1250 K and 0–40 s, respectively. The instrument is enclosed in a vessel designed for hydrogen or inert gas pressures up to 10 MPa. Typical results are illustrated and compared with predictions of a preliminary mathematical model of the kinetics of coal plasticity. The observed kinetics are also discussed with reference to solvent extraction data on the residues of coal samples that have undergone the same temperature-time histories as those employed in the plastometer. The effect of external gas pressure on plasticity is also briefly discussed.