Hydrothermal Treatment of Municipal Solid Waste to Produce Solid Fuel

This paper describes the application of innovative hydrothermal technology on local municipal solid waste (MSW) to produce low chlorine content solid co-firing fuel with coal. Raw MSW was treated at temperatures ranging from 210 to 235°C with 30 to 90 minutes holding period. The process yielded slump products which were then naturally dried to 5% moisture content, resulted in dry products with the heating value up to 24MJ/kg (dry base). Organic chlorine compound from plastic in MSW was converted to inorganic chlorine and reduced to 0.2% level. The inorganic chlorine substances were then removable by water washing at 1:8 product-water ratio (dry base) and vacuum filtration. MSW blends of various proportions (on %wt), with different rank coal were tested in a Thermogravimetric analyzer (TGA). Combustion characteristics like volatile release, ignition were studied. The result showed that even though the blending of MSW with coal is favorable to initiate the early release of volatile, different ignition behavior was observed depending on the blends composition and coal rank. It is found that the effect of early volatile release by MSW on coal ignition differs and depends on quality of coal. The TGA combustion profiles showed that the combustion characteristics of some of the blends can be predicted from the weighted sum of the blend components. With these features, the innovative hydrothermal treatment would then be a good alternative for MSW treatment and conversion into coal co-firing fuel.