Pyrolysis characteristics and kinetics of municipal solid wastes

The large variety in municipal solid waste (MSW) composition and differences in thermal degradation behaviour of MSW components makes modelling, design and operation of thermal conversion systems a challenge. The pyrolysis characteristics of 11 different components, representing the dry cellulosic fraction and plastics of MSW, have been investigated. The aim of this study is to obtain detailed information on the pyrolysis characteristics and chemical kinetics of the most important components in MSW. A thermogravimetric analysis including determination of kinetic parameters are performed at a constant heating rate of 10°C/min in an inert atmosphere. The cellulosic fraction of MSW was modelled by three independent parallel reactions describing the degradation of hemicellulose, cellulose and lignin. The plastics polystyrene, polypropylene, low-density polyethylene and high-density polyethylene were all modelled as single reactions describing the degradation of hydrocarbon polymers. The degradation of PVC was modelled with three parallel reactions describing the release of benzene during dehydrochlorination, dehydrochlorination reaction and degradation of remaining hydrocarbons. Possible interactions between different paper and plastic components in mixtures were also investigated. It was found that the reactivity of cellulosic matter was increased in a mixture with PVC.