METHOD OF OPERATING A MULTIPLE HEARTH FURNACE

摘要

A method of operating a multiple hearth furnace with a plurality of vertically aligned hearth floors includes feeding a first material onto the uppermost hearth floor and moving it over the hearth floor before it falls through a drop hole onto the next lower hearth floor. The first material is processed in this way from hearth floor to hearth floor to the lowermost hearth floor. A second material is fed onto one of the hearth floors to be mixed into the first material. This second material is moved separately from the first material in a separate annular zone of the hearth floor onto which it is fed before it is mixed into the first material, providing an efficient thermal preconditioning of the second material prior to mixing it with the first material without requiring any supplemental equipment.