Apparatus and method for the recovery of fuel products from subterranean deposits of carbonaceous matter using a plasma arc

A method for the situ gasification of a subterranean coal deposit in the absence of appreciable combustion wherein a substantial portion of the volatile matter therein is devolatilized and a substantial portion of the fixed carbon therein is gasified, comprising the steps of:

• a. establishing at least one substantially vertical well shaft communicating with said coal deposit and descending a selected distance into said deposit, the wall of said shaft being permeable to gases in at least a portion of the shaft which is disposed in said deposit;
• b. lowering a plasma arc torch with appropriate electric, plasma gas and coolant supply means into said shaft and positioning said torch in said shaft at a selected gasification level in said deposit;
• c. operation said torch to sustain a plasma arc column;
• d. allowing the coal-bearing wall portions of said shaft proximate said torch to preheat to a temperature at which at least a portion of the volatile matter therein is stripped off;
• e. introducing a reactant into the area proximate said torch to react with the fixed carbon in said coal;
• and
• f. withdrawing the product gas.

In an in situ process wherein a subterranean coal deposit is heated in the absence of appreciable combustion, the improvement comprising:

• operating a plasma arc torch within a coal-bearing segment of a well shaft communicating with said deposit;
• subjecting the face of said shaft adjacent said torch to a flow of steam;
• eroding the shaft adjacent said torch by gasifying a substantial portion of the fixed carbon in said coal in the presence of said steam thereby converting said coal to useful product gases and fluid slag;
• and recovering the product gases through the shaft while allowing at least a portion of the slag to flow downwardly in the shaft.

A method of transforming coal in situ into recoverable gaseous fuel products comprising the steps of:

• a. supplying thermal energy to said coal at a rate of 800 to 2000 kilowatt-hours (KWH) per ton of coal to be gasified utilizing electrical heating means and in the absence of appreciable combustion;
• b. supplying steam to said coal for utilization at a rate of 0.70 to 1.10 tons per ton of coal to be gasified;
• and
• c. producing product gases having an energy content of 100 to 350 Btu per standard cubic foot (SCF) at a production rate of 50 to 120 SCF per KWH energy input.

An apparatus for heating a subterranean stratum of carbonaceous matter surrounding a shaft communicating therewith and recovering the fuel products released thereby, comprising in combination:

• a. a stabilized long arc column forming plasma arc torch having appropriate electric, plasma gas and coolant supply means and being supported in said shaft at a selected position within said stratum;
• b. means for operating said torch to sustain said column including means for operating said torch in a transferred arc mode;
• and
• c. means for collecting fuel products produced by the heating of said deposit.

A method of subjecting a subterranean coal seam stratum to heating for effecting a desired physical transformation of such stratum in order to produce recoverable fuel products, comprising the steps of:

• a. establishing a shaft from the ground surface communicating with said stratum;
• b. lowering a plasma arc torch with appropriate electric, plasma gas and coolant supply means into said shaft and positioning said torch at a selected depth within said stratum;
• c. operating said torch to sustain a plasma arc column;
• d. in the absence of appreciable combustion, utilizing the heat from said plasma column to effect the desired physical transformation of said stratum to recoverable fuel products including the stripping off of at least a portion of the volatiles of said coal in said stratum whereby the volatile gases so stripped off are included in said recoverable fuel products;
• and
• e. recovering said fuel products from said stratum.

A method of subjecting a subterranean coal seam stratum to heating for effecting a desired physical transformation of such stratum in order to produce recoverable fuel products, comprising the steps of:

• a. establishing a shaft from the ground surface communicating with said stratum;
• b. lowering a plasma arc torch with appropriate electric, plasma gas and coolant supply means into said shaft and positioning said torch at a selected depth within said stratum;
• c. operating said torch to sustain a plasma arc column;
• d. in the absence of appreciable combustion, utilizing the heat from said plasma column to effect the desired physical transformation of said stratum to recoverable fuel products and including the step of introducing a reactant into contact with said coal seam and wherein said physical transformation includes the reaction of at least a portion of the fixed carbon in said coal in said stratum with said reactant and the gases so formed are included in said recoverable fuel products;
• and
• e. recovering such fuel products from said stratum.

An apparatus for heating a subterranean stratum of carbonaceous matter surrounding a shaft communicating therewith and recovering the fuel products released thereby, comprising in combination:

• a. a column forming plasma arc torch having appropriate electric, plasma gas and coolant supply means and being supported in said shaft at a selected position within said stratum;
• b. means for operating said torch to sustain said column;
• c. means for introducing steam into said shaft adjacent said torch;
• and
• d. means for collecting fuel products produced by the heating of said deposit.

An apparatus for heating a subterranean stratum of carbonaceous matter surrounding a shaft communicating therewith and recovering the fuel products released thereby, comprising in combination:

• a. a column forming plasma arc torch having appropriate electric, plasma gas and coolant supply means and being supported in said shaft at a selected position within said stratum, said means including a flexible unitary cable structure having in a central portion thereof an insulated electric conductor, a plasma gas line and lines for directing cooling water to said torch and returning such water to the ground surface, said cable structure having a flexible outer cover constructed in a manner allowing said cable structure to serve as a load carrying member for supporting said torch;
• b. means for operating said torch to sustain said column;
• and
• c. means for collecting fuel products produced by the heating of said deposit.