Comparative evaluation of different design configurations for a solid waste incinerator

Due to the widespread use of incineration as a method of waste disposal for solid waste, it is important to have a detailed mathematical modelling and understanding of the incineration process. In this paper the governing equations for mass, momentum and heat transfer for the gaseous phases of the incinerator furnace are described and relevant sub-models are presented. The solid waste bed is assumed to be porous and the process of solid wastes combustion over the bed is divided into four successive sub-processes viz. evaporation of moisture from the solids, volatile release, burning of the volatiles in the gaseous space, and the gasification of char particles with ash formation. Mathematical models were derived for various sections of the solid bed. Gaseous section of the furnace above the solid waste bed was modelled using Fluent software. The solid and gaseous phase models were coupled through their respective boundary conditions. Numerical simulations were performed using different configurations of the primary and secondary air jets, which revealed that the temperature distribution for the outlet flue gas could be avoided by changing the arrangement of primary and secondary air jets.