Process for the gasification of coal in situ

TL;DR: In this article, the authors describe a cyclic process for gasification of coal in situ comprising driving shafts or tunnels into a coal seam, injecting air into the bore holes to ignite and burn the coal to raise its temperature ceasing the flow of air when the coal is hot enough to support the endothermic water gas reaction, and injecting steam into the hot coal formation, such steam preferably being preheated by the flue gases taken from the same end of the bore hole where the air was injected, and recovering product gases, including carbon monoxide and hydrogen, and also

Abstract: Process for the gasification of coal in situ comprising driving shafts or tunnels into a coal seam, injecting air into the bore holes to ignite and burn the coal to raise its temperature ceasing the flow of air when the coal is hot enough to support the endothermic water gas reaction, and injecting steam into the hot coal formation, such steam preferably being preheated by the flue gases taken from the same end of the bore holes where the air was injected, and recovering product gases, including carbon monoxide and hydrogen, and also product oil, exiting the tunnel at the other end of the bore holes. When the temperature of the coal drops during injection of steam to a level which will just permit combustion, the steam flow is stopped, and the cycle is repeated by air injection and flue gas removal at the front end of the bore holes, and through the tunnel connected therewith. This cyclic process is repeated until the entire mass of coal within the area encompassed by the bore holes is exhausted.