Determination of fossil fraction of Refuse Derived Fuel by the Selective Dissolution Method in Calorific value basis: Development of simplified method

Abstract

Determination of net CO2 emissions from combustion of Refuse Derived Fuel (RDF) is not straight forward due to the heterogeneous nature of the fuel. The fossil fraction of the fuel is an essential parameter for the determination of net CO2 emissions. In the present study, the fossil fraction of RDF is determined by means of the Selective Dissolution Method (SDM) in calorific value basis. Seven artificially made RDF mixtures were tested using this method. The mixtures were prepared by mixing different proportions of plastic, paper and wood. It was found that the experimentally determined fossil fractions were very close to the theoretical values, which could be calculated based on the constituents of the artificial RDF mixtures. This indicates a high accuracy of SDM. However, SDM is a time-consuming method. Based on the artificially made RDF mixtures, a functional relationship between calorific value and fossil fraction in calorific value basis was found and plotted graphically. This means that in cases where the nature of the fossil and biogenic RDF constituents is known, determination of the calorific value, ash content and moisture content of the fuel is sufficient for determination of the fossil fraction in calorific value basis. Since these parameters can be relatively quickly determined at least within one day, and are often analyzed anyway as part of the general fuel characterization, this simplified method can save a lot of time and resources compared to SDM, which takes three days to give a test result. Hence, the simplified method can be an attractive alternative to SDM when net CO2 emissions from RDF combustion are to be determined. When performing the SDM analysis, attention should be given for the intermediate calculations since some of the ash forming matter penetrates into the filter paper used in the SDM procedure.