Pyrolysis of Plastics-Free Refuse Derived Fuel Derived from Municipal Solid Waste and Combustion of the Char Products in Lab and Pilot Scales: A Comparative Study

Pyrolysis of refuse derived fuel (RDF) has great potential for energy recovery from municipal solid waste (MSW), while chlorine-related plastics issue was one major barrier for scale up. After screening out plastics, the RDF pyrolysis and char products combustion were evaluated in lab and pilot scales. Thermogravimetry with Fourier transform infrared spectroscopy results suggest that the main RDF pyrolysis reaction occurred in 190-410 degrees C, involving decomposition, decarboxylation, demethylation, and dehydration reactions, with CO2, CH4, H2O, CO, and organic compounds as the main gaseous products. Impacts of temperature and residence time on char yield and proximate composition were evaluated in lab, and a lower temperature was favored. The pilot-scale char had a comparable proximate composition to the lab-scale ones, but a lower heating value, lower H/C ratio, higher O/ C ratio, which may due to different dominant reaction pathways during pyrolysis: apparent demethanation versus dehydration. Thermogravimetry data infers that the combustion performance of pilot-scale char, including combustion stage, weight loss, and kinetic parameters, were close to chars made in lab. Pilot-scale combustion tests show relief of flue gas pollution after upgrading RDF to char, while particulate matter and heavy metals were still main concerns. Lab-and pilot-scale investigations highlight scale up of plastics-free RDF pyrolysis and combustion as a promising and economic alternative for materials and energy recoveries from MSW.