Surrogate Reaction Mechanism for Waste Incineration and Pollutant Formation

The incineration
of municipal solid waste (MSW) is an attractive
technology to generate thermal energy and reduce landfill waste volume.
To optimize primary measures to ensure low emission formation during
combustion, numerical models that account for varying waste streams
and their impact on nitrogen oxide (NOx) formation are needed. In this work, the representation of the fuel
by surrogate species is adopted from liquid fuel and biomass combustion
and applied to solid waste devolatilization and combustion. A surrogate
formulation including biomass components, protein, inorganics, and
plastic species is proposed, and a comprehensive description of the
heterogeneous and homogeneous reactions is developed. The presented
work combines and extends available schemes from the literature for
woody and algae biomass, coal, and plastic pyrolysis. The focus is
set on the prediction of fuel NOx and
its precursors, including cyclic nitrogen-containing hydrocarbons.
Additionally, the interaction of NOx with
sulfur and chloride species is accounted for, which are typically
released during the devolatilization of MSW. The model allows for
predicting thermogravimetric analysis measurement of waste fractions
and different waste mixtures. The proposed kinetic mechanism well
reproduces NOx formation from ammonia
and hydrogen cyanide and its reduction under selective non-catalytic
reduction conditions. The chemical model is successfully applied to
predict the released gas composition along a grate-fired fuel bed
using a stochastic reactor network.