Allis-chalmers Corporation

Paul D Hess

James L Shy

A calcining combustor for the suspension preheater of a rotary kiln cement manufacturing plant having a cooler for the clinker comprises an upright furnace vessel having an outwardly spiraling gas exhaust duct at its upper end leading to a preheater gas/meal separator and a mixing portion at its lower end; an inlet for hot combustion air from the cooler into the mixing portion; an inlet for cement meal from the preheater into the mixing portion downstream from the combustion air inlet to entrain the meal in the rising combustion air; and burners for injecting fuel into the air/meal stream downstream from the meal inlet to calcine the meal by heat released by burning of the fuel with the combustion air. The initial calcination temperature is a minimum because the combustion air atmosphere within the combustor is devoid of significant amounts of carbon dioxide and chlorine and alkali vapors typically present in kiln-off gases, and the endothermic calcination reaction absorbs heat energy to limit temperature rise within the combustor so that caking and formation of alkali and nitrogen oxide vapors is minimized. An alternative embodiment has an inlet for hot kiln-off gases into the furnace vessel at a point where substantial calcination has occurred so that both (a) calcining and (b) mixing of the calcined meal/air stream with the kiln-off gases to transfer heat energy thereto occur in a single vessel.

Method for heat treating pulverous raw material calcining combustor

A multi-stage cement calcining plant suspension preheater has a calcining combustor flow connected with a cyclone separator in the uppermost stage and helical duct inertial separators in the remaining stages which are lower in height and in pressure drop than conventional cyclone separators and permit reduction in height of the preheater tower and use of a lower horsepower fan to move kiln-off gases through the preheater.

Suspension preheater for cement calcining plant

A helical duct separator particularly suited for use in the suspension preheater of a cement calcining plant to separate raw cement meal from kiln-off gases in which the meal is suspended comprises a hollow elongated continuous duct having its longitudinal axis disposed along a downwardly inclined helical path, an inlet opening in a vertical plane for receiving a horizontal stream of gas with entrained meal, a downwardly inclined upper wall and a concave outer sidewall in the path of the gas stream to deflect the gas stream into a downwardly inclined helical path, a horizontal bottom wall adjacent the outlet end of the duct, a meal exit opening in the bottom wall and a gas exhaust opening in a horizontal plane in the upper wall adjacent the outlet end of the duct. The gas stream so directed in a downwardly inclined helical path impinges on the horizontal bottom wall and is deflected upward and drawn upward by suction from an induced draft fan toward the gas exhaust opening while the heavier meal is precipitated from the gas stream and urged by centrifugal and inertial forces to flow along the bottom wall and through the meal exit opening. The helical duct separator is substantially shorter in height, and has a substantially lower pressure drop, than a cyclone separator, thereby permitting reduction in the height of, and the energy required to operate, a suspension preheater in comparison to one of the cyclone separator type.

Helical duct gas/meal separator

A suspension preheater adapted to be connected to the feed end housing of a rotary kiln or the like, whereby kiln exhaust gas emerging from the feed end housing passes through the preheater in countercurrent heat exchange relation with particulate feed material for the kiln which passes through the preheater from a feed inlet end contiguous the upper end of the preheater to a feed discharge end at the lower end of the preheater, comprising one or more cyclone means arranged in series gas and particulate feed material flow relation with respect to each other, means for admitting the particulate feed material from a feed material supply source to the upper portion of the preheater, a hollow preheating chamber at the lower portion of the suspension preheater, the hollow preheating chamber having the upper end thereof in gas and material flow communication with the upper end of the lowermost of the cyclone means, the lower end of the hollow preheating chamber being in gaseous flow communication with the feed end housing of the rotary kiln, a first particulate material delivery pipe connecting the lower portion of the lowermost cyclone means to the interior of the hollow preheating chamber intermediate the height of the preheating chamber, and a second particulate material delivery pipe connecting the lower portion of the lowermost cyclone means directly to the interior of the feed end housing of the kiln.

Growing community of inventors

Brookfield, WI, United States of America

Paul D Hess