UNDERGROUND GASIFICATION OF BROWN COAL FIN AND MID-THICKNESS SEAMS Russian patent published in 2014 - IPC E21B43/295 E21B43/30 C10J3/02 

FIELD: mining.

SUBSTANCE: proposed method comprises drying of coal seam, injection of oxidiser into reaction channel via vertical injection well, suction gasification products therefrom via gas discharge wells and minimisation of pressure in reaction channel. Note here that, additionally, two vertical wells are drilled to coal seam surface and two vertical 100-140 m long wells are drilled at boundaries of gasified coal seam at 50-60 m from each other. Besides, injection wells are drilled at the center of section under analysis with spacing of 15-20 m. Used oxidiser is atmospheric air with addition of steam-oxygen mix in amount of 20000-50000 m³/h Combustion face temperature is kept up equal to 550-700°C Combustion face is controlled by changeover to injection well which combustion face approaches and by varying the amount of forced oxidiser.

EFFECT: stable combustion in combustion face of filtration channel, higher calorific value of power gas at underground gasification.

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