Method and apparatus for recovering energy from wastes by combustion in industrial furnaces

A method to utilize the energy content of an at least partially combustible organic-containing waste in a system for heat treating inorganic particles in a rotary furnace, comprising:

• subjecting the raw inorganic particles to at least one of the steps of preheating and calcining;
• thereafter heat treating the inorganic particles at a higher temperature in the rotary furnace;
• cooling with air the inorganic particles discharged from the rotary furnace in a manner to elevate the temperature of at least a first portion of the air sufficiently to be capable of decomposing the combustible portion of the waste;
• flowing the hot exhaust gases from the rotary furnace to use in at least one of the preheating and calcining steps;
• flowing through a tertiary air duct said hot first portion of the air used to cool the inorganic particles discharged from the rotary furnace;
• feeding the waste, continuously or in batches, directly into the tertiary air duct at a position therealong, at a rate, and in a condition so as to be effectively largely decomposed and at least partially burned by the hot air flowing therethrough;
• discharging from the tertiary air duct any air and the resulting decomposition and combustion gases ultimately to feed at least one of the preheating and calcining steps wherein the burning of any decomposition gases is completed;
• and
• removing from the tertiary air duct any solid residues remaining therein from the decomposed waste.