A shaft preheater to achieve an improved adaptation of layer height to particle
size spectrum of material to be preheated. The shaft preheater includes a plurality
of shafts for receiving lumpy material, an arrangement for filling the individual
shafts with the lumpy material to be preheated and means for limiting the layer
height in the shafts. The means for limiting the layer height include a needle
valve and have an arrangement for coarse adjustment and an arrangement for fine adjustments.
