Description of Multiple-Hearth Furnace
Haug, and Lundberg estimated that about 400 multiple-hearth furnaces (MHF) for biosolids incineration have been sold; it is not known how many are still in operation. The MHF is designed to reduce to ash the quantity of biosolids fed to it. The treatment (volume reduction) of the biosolids fed into the MHF takes place under high temperature so that the resultant product is an inert sterile ash. The MHF model used is earth-friendly. That is, the furnace operates as designed while maintaining a pollution-free atmosphere. The MHF is constructed of a high temperature refractory brick-lined shell that contains eight levels of hearths. Within the furnace, drying, burning, and cooling of the biosolids takes place as the biosolids moves from the top of the furnace to the bottom. The multiple-hearth furnace described here consists of a variety of components. Each component is important and is required to ensure system performance at optimum capacity for efficient solids processing.