Method of and apparatus for efficiently combusting low grade solid fuel

摘要

Oil shale having a heating value (calorific value) which varies over a relatively wide range is combusted by supplying the oil shale and a further fuel having a greater heating value to a combustor (22). The oil shale is fed to the combustor (22) at a substantially fixed rate, independently of the heating value of the oil shale, and the further fuel is fed to the combustor at a rate which is controlled so that the heating value of the fuel mixture in the combustor remains substantially constant in the face of variations in the heating value of the oil shale. Preferably, the temperature of the combustion products is the parameter used to control the rate at which the further fuel is fed to the combustor. <MATH>