As shown schematically in FIG. 1, hot gases, containing 
molecular oxygen, from generator elements, (14) and (19), pass through a 
bed of 
coal chunks in an ODD reactor chamber (2). The 
molecular oxygen content of these hot gases is less than stoichiometric, relative to the 
coal volatile matter content, so that 
partial oxidation of only the volatile matter occurs within the ODD reactor chamber, (2), during devolatilization therein. Two products are thusly created, a partially oxidized, and hence cleaner burning, volatile matter 
fuel gas, and a 
solid devolatilized 
coke. The hot 
coke is transferred, by overfeed, into a 
coke reaction chamber, (7), where counterflowing primary air, via air meter, (12), gasifies the coke into 
carbon monoxide with some 
carbon dioxide. Finally, the 
carbon monoxide and the partially oxidized volatile matter, are admixed with overfire air, and burned fully to 
carbon dioxide in overfire burner chambers, (23), (26). The resulting hot burned gases flow into the 
nozzle inlet, where, after mixing with bypass air, they expand through the expander portion of a gas 
turbine engine. 
Coal ashes accumulate at the bottom, (9), of the coke 
reaction chamber, (7), where the overlying coke chunks prevent ash particle carryover into the 
turbine blades. Low cost 
coal can thus be cleanly used as an 
energy source for gas 
turbine engines.