Underfire air and steam system and incinerating process for a controlled starved-air incinerator

An underfire system for a controlled starved-air incinerator and incinerating process which minimizes high localized temperatures in the main combustion chamber to lessen clinker formation and vaporization of inorganics for minimizing the particulate emission rate and which maximizes conversion of the fixed carbon portion of the waste materials into volatile matter for maximizing the thermal efficiency of the incinerator. The underfire system supplies air at less-than-stoichiometric requirements which creates an exothermic reaction between some of the fixed carbon in the waste material and the oxygen in the air to produce volatile carbon dioxide. In addition, steam is supplied to the burning waste materials, preferably alternately with the air supply, for creating an endothermic "water-gas reaction" between additional fixed carbon in the waste material and the steam to produce volatile carbon monoxide and hydrogen gas and for absorbing undesired heat from the exothermic reaction.