Subterranean gasification of coal - using matrix of bore-holes for charging gasification agent and discharging prods., minimising costs

The subterranean gasification of coal incorporates defining the limits of the coal masses in layer by imaginary lines and offsetting the boreholes, by which the gasifications agent is introduced and by which the gaseous products are discharged, w.r.t. the coal front at which the reaction is taking place, in the direction of progression of the gasification. The corresp. feed and discharge holes are at a distance from one another in a direction perpendicular to the progression of gasification, so that the gasification agent circulating from one to the other is in contact with the coal mass. The gasification agent is e.g. air, O2, H2, CO2 and/or steam. The costs of preparing and exploiting the coal layer are minimised. Gasification is possible independently of the disposition and thickness of the layers, and in the case of horizontal as well as inclined layer. A less dense system of pipes is needed than with other installations; the surfaces are less covered and can be used for agriculture. Gasification under high press. e.g. 10-60 bar is possible and gives good contact, partic, useful in the case of coals which are difficult to gasify.