In situ rapid pyrolysis and steam gasification of lignite coals: A mechanistic study

This work presents a kinetic study of the catalyzed steam gasification of lignite coals and addresses the issue of concurrent coal pyrolysis and gasification. Coal pyrolysis was performed under steam pressure conditions ranging from 2.4 kPa to 410 kPa. The yields of CO, CO;Because of the importance of temperature in the kinetic study of pyrolysis and the difficulties involved in its determination under rapid heating conditions, this work utilized an innovative approach. Under such an approach, the particle temperature was established by a heat transfer model which relied on the temperature measurement of the gas immediately adjacent to the sample while being heated. A rate constant for coal pyrolysis was determined utilizing the predicted particle temperature (k = 10;The gasification rate of the in situ formed coal-chars was determined by monitoring the evolution of CO and CO;The gasification data were tested with a mechanism that involved dissociation of water on a catalytic site followed by oxygen transfer to a carbon site limited by thermodynamic equilibrium of the water-gas shift reaction.