Pyrolysis of coal at high temperatures

Knowledge of the behaviour of the many volatile species liberated during pyrolysis is warranted, since their composition, rate of release and secondary reactions will have an important influence on such practical considerations as ignition, rate of combustion and trace gaseous and particulate emissions. This paper presents data on the pyrolysis of a subbituminous coal and of tar produced by rapid pyrolysis in a small fluidised bed reactor and in a shock tube. Kinetic parameters for light gas formation from secondary reactions of the tar have been determined. The results also provide evidence that secondary reactions of the tar are a source of polycyclic aromatic hydrocarbons (PAH) observed during pyrolysis. Data are also presented to show the effect of preparation conditions on the combustion kinetics of chars produced by rapid pyrolysis.