A METHOD FOR THE UNDERGROUND GASIFICATION OF COAL OR BROWNCOAL

摘要

A method for the underground gasification of coal or browncoal in an inclined coal layer, in which two boreholes are drilled into said layer, and are continued downwards in a converging manner with the inclination of said layer. After initiating the combustion of the coal, the cavity formed thereby is filled by a granular filler material suspended in a carrier substance supplied through a borehole, the cavity then being filled with the exception of a narrow channel in which the combustion of a substantially straight coal front can be continued. When using a carrier liquid, the latter is pressed out by means of a pressurized gas before restarting the combustion. If water is flowing in from the surrounding formations, it can be kept away from the filler near said channel by barometric action by means of a tube extending downwards in a borehole to the desired water level, the pressure being maintained during combustion, e.g. by including suitable throttle means in the gas discharge.