| abstract |
Apparatus and method for gasification of carbonaceous matter by plasma arc pyrolysis are disclosed. In one embodiment, a refractory-lined furnace is provided with a depression along its base for holding a pool of molten metal which acts as the external electrode for a bank of long arc column plasma torches which provide a heat mass for the process. The plasma arc pressure imparts momentum to the surface of the melt and causes it to flow in cusping eddy currents during the process. Crushed coal is deposited through the roof of the furnace by a rotary feeder in continuous plural streams. The coal is devolatilized in a matter of milli seconds and the volatiles are cracked as the coal falls by gravity through the interior of the furnace. The remaining carbon-rich char collects at plural sites on the surface of the melt and the mounds of char are rotated by the eddy currents. Steam is continuously injected into the furnace to produce hydrocarbon gases through reaction with the carbon-rich char. A residence time of five to thirty minutes produces carbon utilization of up to 92 percent. The hot raw gases are directed through a gas cooler where heat is extracted for producing the process steam and the cooled raw gases are upgraded to pipeline quality by conventional carbon dioxide and moisture removal techniques and by methanization with catalysts. The raw gas may also be burned directly as a medium-Btu gas or used as a reductant in the direct reduction of iron ore. |