CFD Modeling of Grate Furnace Designs for Municipal Solid Waste Combustion

The average amount of municipal solid waste (MSW) generated in Malaysia is 0.5–0.8 kg/person/day and has increased to 1.7 kg/person/day in major cities. As rapid development continues, so does the amount of MSW and thus a lack of space for new landfills. Thus a better way of disposing MSW would be to incinerate. The basic design requirements of high-performance incinerators are the 3Ts (time, temperature, and turbulence). An adequate retention time in a hot environment is crucial to destroy the products of incomplete combustion and organic pollutants. Also turbulent mixing enhances uniform distributions of temperature and oxygen availability. With today’s ever increasing computer power, CFD modeling has now become a useful tool for modeling complex geometry and flow conditions in the incinerators. CFD combustion and flow simulations can enable detailed parametric variations of design variables. Bed combustion was done using FLIC 2.3C and the CFD modeling of an industrial scale MSW incinerator design was done using FLUENT Ver. 6.2.18. The 2D modeling was based on conservation equations for mass, momentum and energy. The kwas employed for turbulent flow modeling. The meshing was done using Gambit 2.2.3. The Generalized Finite Rate model was used to simulate hot flow inside the chamber. Simulations have resulted in predicting the combustion behavior in various grate furnace designs. The emissions behaviour in various sections of the combustors have been modeled to a reasonable accuracy.