Gasification studies of model refuse derived fuel (RDF)

Abstract

Refuse Derived Fuel (RDF) is the refined form of the Municipal Solid Waste (MSW). Since there is a heterogeneity issue with using ‘as obtained’ RDF, a model RDF composition is utilized in this study. Conversion of RDF to produce syngas via pyrolysis and gasification was explored. Model RDF pyrolysis showed an additive behavior which was verified by comparing the weight loss curves, gas composition and heat effects of individual components with the composite. Gasification behavior of the model RDF char in carbon dioxide exhibited a synergistic effect, which was attributed to the redistribution of potassium during the gasification process. The effect of the inorganics was also evident when steam was used as the gasifying agent. Reaction mechanisms were established to explain char gasification in both carbon dioxide and steam. Effect of potassium on gasification reactivity was quantified. KOH was found to be a better gasification catalyst than potassium oxide. Further, effect of heating rate and residence time were explored on the char physicochemical structure and gasification reactivity. The results from the fundamental studies were applied to design a bubbling fluidized bed reactor (BFBR) for the gasification of RDF pellets. High temperature (900 °C) and small amounts of oxygen (500 ppm) in steam gasification resulted in the highest carbon recovery, lowest tar generation and highest thermal efficiency compared to the other experimental conditions used. Finally, a summary of the results and suggestions for future work are discussed.