US 4,060,375 AGranted

Methods and apparatus for the heat treatment of fine-grained materials

AssigneePolysius AG

InventorsPaul Weber, Hans Mollenkopf, Kurt Henning, Otto Heinemann, Heinz-Herbert Schmits, Wolfgang Rother, Horst Ritzmann, Jurgen Wurr, Karl Krutzner, Jr., Werner Schossler, Wolf Goldmann, Georg Schepers

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Abstract

Fine-grained material such as raw ground cement adapted to be fired in a rotary tube furnace is introduced to a vertical preheater and falls through a heating zone located at a level below the level at which the material enters the preheater. A stream of air enters the preheater at a level below the heating zone and passes upwardly at sufficient velocity to entrain the material that has passed through the heating zone, thereby causing such material to pass again through the heating zone. From the preheater the material is delivered to the furnace for final firing.

Claims14

Dependent claims

A method for the heat treatment of fine-grained material prior to firing said material in a furnace having a walled, vertical waste gas conduit, said method comprising conducting a waste gas stream from said furnace upwardly through said conduit at a predetermined velocity;

supplying fine-grained material having a grain size so related to the velocity of said gas stream that no substantial portion of said material is entrained by said gas stream;
introducing said material into said conduit at a first level between its upper and lower ends so that said material will fall downwardly in opposition to said gas stream toward the lower end of said conduit;
combusting fuel in said conduit at a second level below said first level to provide a heating zone below the level at which said material is introduced to said conduit;
and deflecting downwardly moving material inwardly of said conduit toward the center thereof and at a level above that of said heating zone to assure that said downwardly moving material passes through said heating zone as said material falls toward said lower end of said conduit.

1 more element

Dependencies are inferred from the claim text.