Investigation of the slagging and fouling aspects of co-firing coal and organic refuse-derived fuel

Abstract

Almost half of municipal solid waste deposited in landfills comprises organic components. Processing organic waste into refuse-derived fuel will enhance the waste’s chemical and physical characteristics, making it similar to solid fuel. This fuel can be used as a co-firing mixture in coal-fired power plants. Conversely, utilizing organic RDF (RDF-O) in pulverized coal boilers will cause ash-related problems, such as slagging, fouling, and corrosion, during combustion due to high alkali and chlorine contents. This study discusses the impact of ash problems and RDF-O comprising 5–20 wt% of coal using comprehensive analysisof empirical calculations, ash characteristics analysis, drop tube furnace (DTF) combustion, ash morphology, and mineralogy using SEM-EDS and XRD. The results show that the total chlorine in RDF-O (1985 ppm) increases the total chlorine in the blend samples (228, 323, 418, and 512 ppm), exceeding that in coal (131 ppm). Co-firing coal and RDF-O up to 10 wt% results in clean probe observation, relatively low gas emission, no sintering ash morphology, and minerals with high-melting temperature, indicating that this composition has a low tendency of slagging, fouling, and corrosion. RDF-O 15 wt% sample has small spots in the slagging and fouling probe which indicates there is some potential slagging and fouling tendency. Moreover, the addition of RDF-O up to 20 wt% clearly indicates a serious ash-related problem as shown on both probes representing slagging and fouling areas.