RELATIONSHIP BETWEEN RESULTS FROM CONVENTIONAL PROXIMATE ANALYSES AND PYROLYSIS YIELDS UNDER RAPID-HEATING CONDITIONS

A variable heating rate wire-mesh apparatus has been used to investigate the effect of heating rate on a range of coals from approximately 70% to 90% C dmmf. Coals in the range 80% to 85% C dmmf were found to be the most sensitive to the heating rate used, possibly due to their exhibiting the greatest differences in plastic behaviour between slow and fast heating. By using a similar time/temperature history to the standard ASTM proximate volatile matter test in the wire-mesh reactor, it was shown that, for medium rank coals, secondary char-deposition reactions in the VM crucible could account for about half of the differences between the proximate VM yields and the total volatile yields for 5000 K/s heating to 950°C. © 1990.