F. L. Smidth & Co.

Dan S Hansen

A plant is disclosed for heat treating pulverous raw material such as cement raw meal prior to a final sintering process in a rotary kiln. The plant includes a rotary kiln having an upper material inlet end portion for the reception of preheated cement material and a lower material outlet end portion for exiting the final sintered kiln product. A multi-stage cyclone string preheater having at least a first stage for receiving the cement raw meal has a last stage communicating with the upper material inlet end portion of the kiln. A smoke chamber connects the upper material inlet portion of the kiln with the preheater, and a scoop chamber connects the kiln with the smoke chamber. The scoop chamber is adapted to receive preheated, at least partially calcined raw material from at least one preheater stage other than the last stage. The cement material received in the scoop chamber is dispersed so as to be suspended in the gases exiting the kiln and directed through the smoke chamber to the last stage of the associated preheater string. The preheated, at least partially calcined cement material is then directed from the last stage of the preheater string to the upper material inlet end portion of the kiln at a location upstream with respect to the kiln exiting gases, off the location of the dispersing means, so as to pass down through the kiln for further heat treatment.

Rotary kiln plant

A method is disclosed for burning alkaline raw materials in an inventive rotary kiln plant. According to the method, cold atmospheric air is introduced tangentially into a circular chamber mounted either within, or adjacent to, the raw material inlet end of the kiln such that a circulating stream of cold air is produced in the chamber around a stream of exhaust gases passing from the kiln to the chamber. A part of the exhaust gases are thereby cooled by the cold air, and alkali vapors therein are condensed out of, and onto, dust particles in the exhaust gases. The alkaline-coated dust particles are thus subsequently discharged from the chamber. The invention also relates to a rotary kiln plant for practicing the inventive method.

Method of heat treating raw materials and rotary kiln plant therefor

A method of burning pulverous or granular material in a plant including a suspension preheater and a rotary kiln having an integrally mounted planetary cooler for cooling the burnt material exiting from the kiln by means of air subsequently used for combustion and preheating in the plant. The method comprises directing the heated cooling air from the planetary cooler into the rotary kiln, dividing the heated cooling air into two streams, directing the divided cooling air out of both ends of the kiln in its divided streams, directing at least one of the streams of the heated cooling air into the rotary kiln and utilizing the stream as combustion air in the rotary kiln, thereafter directing the stream as part of a waste gas out of one end of the kiln to the preheater for use in preheating the raw material fed into said preheater, drawing the other stream of heated cooling air out of the other end of the kiln and directing said other stream of cooling air to the suspension preheater for use in preheating raw material fed into said preheater. An apparatus for practicing the method of the invention is also disclosed.

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Copenhagen, Denmark

Dan S Hansen