Modeling of early cavity growth for underground coal gasification

A one-dimensional unsteady-state model has been developed to predict the movement of the cavity wall and drying front during the initial period of coal block gasification (lateral cavity growth). In determining the movement of the cavity wall, linear shrinkage of coal and surface reactions of H/sub 2/O, O/sub 2/, and CO/sub 2/ with the cavity wall are considered. The model predictions have been compared with results from an experiment where Texas lignite cores were combusted under a variety of conditions which simulate lateral cavity growth. The model gives good agreement between computed and experimental results.