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Show Performance of Third Generation Rotary Kiln Incinerator John Petersen and Mike Keller Callidus Technologies Inc. and particulate carryover to downstream equipment. If sufficient air were added to quench the temperature, entrainment would rapidly increase and, in addition, this event would occur when the temperature was abnormally high resulting in a propensity to produce softened (molten) particulates which can plug downstream equipment. 2. If excess air is not available, this excess fuel will tend to run the temperature down, reducing fuel vaporization rate and slowing down the process-a significantly more desirable reaction. Air is introduced into the kiln intentionally through the burner and various air injection nozzles. Obviously, the designer can control air flows through each of these channels by installing appropriate meters and control valves. However, air is also introduced into the kiln by parasitic leakage through the area between the rotating kiln shell and the fixed feed and ash hoods. These air flow leakages can be substantial and m a y indeed be larger than the combined air flows through the burner and the air injection nozzles-in most cases the combustion process responds only to the total available air. Although control of the total air flow is technically desirable, the ability to produce a kiln which provides air control relies on the ability to seal the rotating drum to the fixed feed and ash hoods. This is not a simple task. Consider that from start up to operating temperatures, the diameter of a 12' L D . steel kiln m a y grow as much as 0.5 inches and the length of a 40' kiln can increase as much as 1.75 inches. In addition, a kiln continuously moves uphill and downhill on the trunnions to prevent excess localized wear on the tires and trunnions. The seals are of obvious importance but no seal system will be effective unless the kiln has been built to appropriate tolerances. The following factors must be considered: V-33 4 |