In situ gasification of bituminous coal

摘要

In the underground gasification of a swelling coal the bulk permeability of the coal proximate to the linkage between the injection and the production holes is increased and the plugging of the linkage during the in situ combustion and gasification procedure is suppressed by subjecting this coal proximate to the linkage between the injection and production holes to a stream of air heated to a temperature below the softening point of the coal prior to the in situ combustion and gasification procedure.