Pyrolytic incineration operates on a starved air principle, and air supplied to the pyrolysis chamber generally constitutes less than half of the stoichiometric air requirement for combustion of the waste. The low air supply rate achieves partial combustion and vaporization of the waste, and results in low gas velocity and turbulence in the pyrolysis chamber which minimizes mechanical entrapment of particulate matter in the waste gases.
The waste gases from the pyrolysis chamber, then pass into the thermal reactor section of the incinerator which is located in the stack. Atmospheric air is drawn into the thermal reactor section to achieve substantially complete combustion of the combustible waste gases in a second zone of combustion.
The normal incinerator is designed for peak thermal capacities, and the peak capacity is rarely attained except when waste material is being charged into the combustion chamber. Consequently, the incinerator is normally operating well below peak capacity.
Certain liquid wastes, such as solvents, paint, lacquer, and the like, have a high BTU content, while other water base liquid wastes have a relatively low BTU content. In addition, the viscosity and solids content of the liquid waste can vary considerably.
In the past, incinerators have been designed to separately burn either solid or liquid waste materials and in some cases, incinerators have been designed with sequential combustion chambers to handle both liquid and solid waste. However, none of the incinerators, as used in the past to handle both solid and liquid waste materials have been programmed to utilize the spare, below-peak capacity of the solid waste incinerator.