Combustion modelling of an industrial municipal waste combustor in Malaysia

Abstract

Disposal of Municipal Solid Waste (MSW) in Malaysia by open incineration is increasingly becoming a problem. There is public concern about any pollutant emissions. Design requirements of high-performance incinerators are sometimes summarized as the achievement of 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. Turbulent mixing enhances uniform distributions of temperature and oxygen availability. Computational fluid dynamics (CFD) modelling is now in the development phase of becoming a useful tool for 3D modelling of the complex geometry and flow conditions in incinerators. CFD flow simulations can already permit detailed parametric variations of design variables. CFD modelling of an industrial scale MSW incinerator was done using FLUENT. The 3D modelling was based on conservation equations for mass, momentum and energy. The differential equations were discretized by the Finite Volume Method and were solved by the SIMPLE algorithm. The k-ε turbulence model was employed. The meshing was done using Gambit 2.0. The cold flow simulations were performed to develop the flow and velocity field. Numerical simulations of the flow field inside the primary and secondary combustion chambers have provided the temperature profiles and the concentration data at the nodal points of computational grids. Parametric study was also done to minimize the NOx emissions. Disposal of Municipal Solid Waste (MSW) in Malaysia by open incineration is increasingly becoming a problem. There is public concern about any pollutant emissions. Design requirements of high-performance incinerators are sometimes summarized as the achievement of 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. Turbulent mixing enhances uniform distributions of temperature and oxygen availability. Computational fluid dynamics (CFD) modelling is now in the development phase of becoming a useful tool for 3D modelling of the complex geometry and flow conditions in incinerators. CFD flow simulations can already permit detailed parametric variations of design variables. CFD modelling of an industrial scale MSW incinerator was done using FLUENT. The 3D modelling was based on conservation equations for mass, momentum and energy. The differential equations were discretized by the Finite Volume Method and were solved by the SIMPLE algorithm. The k-ε turbulence model was employed. The meshing was done using Gambit 2.0. The cold flow simulations were performed to develop the flow and velocity field. Numerical simulations of the flow field inside the primary and secondary combustion chambers have provided the temperature profiles and the concentration data at the nodal points of computational grids. Parametric study was also done to minimize the NOx emissions.