CORRELATION OF GASIFICATION REACTIVITIES WITH CHAR PROPERTIES AND PYROLYSIS CONDITIONS USING LOW RANK CANADIAN COALS

During the flash pyrolysis and flash hydropyrolysis of coals performed at relatively low temperatures (around 650 °C) to maximize liquid product yields, a large amount of char is obtained. It is expected that this char will be gasified to produce synthesis gas or to generate electricity. In this work the gasification rates of chars produced by flash pyrolysis or flash hydropyrolysis of different Canadian coals were measured to investigate the effects of pyrolysis conditions on char reactivity. Gasification measurements were made by the temperature programmed reaction (TPR) method in an air atmosphere. Data obtained were analysed using the Bhatia-Perlmutter model to obtain gasification rate parameters. These were used to represent char reactivity. In all cases, reactivity of a char decreased as the severity of the pyrolysis step increased. Several char properties such as pore surface area, amount of chemisorbed oxygen and residual volatile matter were measured in addition to the proximate and ultimate analyses to see if one or more of these properties would serve as a reactivity index. The amount of chemisorbed oxygen was found to be the best index. © 1990.