CO-COMBUSTION OF REFUSE-DERIVED AND PACKAGING-DERIVED FUELS (RDF AND PDF) WITH CONVENTIONAL FUELS

Abstract

Energy recovery of used materials can be performed as mixed municipal solid waste (MSW) incineration or as fuel recovery for co-combustion. Recovered fuels are refuse-derived fuel (RDF), which is mechanically separated and processed from MSW, and packaging-derived fuel (PDF), which is the source-separated, processed, dry combustable part of MSW. A one-year co-combustion of RDF with peat and coal was carried out in a 65 MW circulating fluidized-bed (CFB) boiler power plant. The efficiency of the combustion process and the corrosion behaviour of the boiler were particular focuses of attention in this study. Five different PDFs were also co-combusted in the same power plant. A wide analytical programme was carried out including the solid and gaseous emission measurements. All PDFs and RDF performed technically well and the emissions were low. Small particle size and stable feeding of RDF/PDF were important for effective combustion. Low CO emissions showed clean and efficient combustion. SO2emissions decreased, because part of the coal was replaced by RDF or PDF. HCl emissions increased when the chlorine content of the fuel mixture increased, because limestone injection was not used. Heavy metals concentrated to the fly ash in unleachable form. PCDD/F emissions were on the normal power plant level and far below the strictest incineration limit. Long-term co-combustion of 10% RDF with peat and coal did not cause any high temperature chlorine-induced corrosion of the superheater materials (480°C). The results showed that it is useful and technically possible to combine resource and waste management in the form of fuel recovery and energy production in the normal power plants.