Low pollution incineration of solid waste

Abstract

An incinerator system and method wherein pieces of solid waste, such as fragments of wood, are conveyed in such a fashion as to become disposed within a fluidized bed of an incinerator vessel. Preferably the solid waste particles are caused to be somewhat homogeneously dispersed within the fluidized bed. The solid waste particles may be 'pre-dried' or moisture may be added to the particles prior to deposition in the fluidized bed for optimum results, depending upon circumstances. In one embodiment, the fluidized bed is situated above an air delivery chamber at the bottom of the vessel and supports combustion of the solid waste particles in the fine granular material comprising the fluidized bed. The fine granular material is supported by a perforated plate. The air delivery system channels high temperature air into and up through the fluidized bed until operating temperature is reached and so channels ambient air thereafter. Volatile matter given off by combustion of the solid waste particles in the fluidized bed is burned smokelessly in the vapor space immediately above the bed. A vortex generator system is used with or without vertical stagnation columns so that all air flow caused by the heat of the bed is collected in an annular ring near the wall of the vessel which centrifuges fine particles comprising the bed as well as some of the small pieces of solid waste which escape from the bed prior to full combustion. Other pieces of solid waste are retained within the vapor space of the vessel due to the increased residence time created by the vortex generator system until consumed. Thus, efficiency is increased. Special bed nozzles supported by the perforated plate in one embodiment or by air ducts in another embodiment and to which air from the air delivery system is selectively channeled aids in improved combustion providing below the horizontal plane defined by the outlets of the bed nozzles a region in which tramp material is either trapped and stored or trapped and removed in a manner preventing deterioration of the good quality fluidized bed properties necessary for optimum combustion. A novel fluidizing air system comprising parallel, spaced air ducts, creating uniform air distribution and nozzle discharge, accommodates continuous recirculation and purification of bed material during normal burner operation is provided as is the unique use of olivine as the bed material and the novel injection of fuel into the burner using an air jet mechanism.