METHODOLOGY FOR MODELING THE DEVOLATILIZATION OF REFUSE-DERIVED FUEL FROM THERMOGRAVIMETRIC ANALYSIS OF MUNICIPAL SOLID-WASTE COMPONENTS

The capacity of waste-to-energy (WTE) plants in the U.S. is expected t o double by the year 2000. Many of these plants will burn refuse-deriv ed fuel (RDF) consisting of municipal solid waste (MSW) components. A large percentage of the mass of RDF is volatile matter, which when com busted, contributes significantly to the boiler heat rate. A methodolo gy is presented for estimating the devolatilization characteristics of RDF based on the premise that RDF can be modeled as some combination of select MSW components. Thermogravimetics analyses of these componen ts provide the input data to the methodology. The outputs from the met hodology are calculations of volatile weight loss versus temperature, or calculated thermograms, for the components at user-defined conditio ns. The hypothesis was made that these thermograms could be summed, gi ven the mix of components in the RDF, to give an accurate description of the devolatilization process for the RDF. This hypothesis was teste d by performing thermogravimetric analysis on MSW components that incl uded newspaper and plastic consumer goods made from polystyrene foam, polyethylene terepthalate, polypropylene, and high-density polyethylen e. These components were analyzed both as individualo samples and and as a controlled mixture that served as a surrogate RDF sample. The sam ples were heated within the thermogravimetric analyzer (TGA) at a rate of 50-degrees-C/min in a nitrogen flow. Thermograms were calculated f or the components and then summed according to the methodology. The ca lculations matched the thermogravimetric data for the surrogate RDF sa mple, thus supporting the hypothesis that RDF devolatilization is desc ribed by the superposition of the volatile weight loss for the constit uent materials.