Gaseificação em leito fluidizado da fração polimérica contida no rejeito (FPR) proveniente da triagem de resíduos sólidos urbanos (RSU)

Abstract

The worldwide solid waste composition indicates that polymeric materials account for, approximately, 10% of municipal solid waste (MSW). The MSW after sorting still contain a plastic fraction (FPR) made of recyclable waste, which is a potential raw material for thermochemical processes. Among the thermochemical processes, combustion, pyrolysis and gasification are the most important. Gasification has been use for the conversion of polymeric residues to combustible gas. This study reports the steam gasification process of the FPR after the MSW sorting from the differentiated collection in the city of Garibaldi - RS. The samples were obtain from Garibaldi Cooperative of Recyclable Material Collectors. It was found that 29.8% of the MSW after sorting are polymeric materials, incorrectly sent to landfill. The FPR was characterized by gravimetric composition, particle size distribution, ultimate and proximate analyzes. The residues with the highest participation in FPR are polypropylene (28.77%), polystyrene (23.53%) and polyethylene (16.67%). The gasification experiments were run in a fluidized bed reactor at three different temperatures (800, 850 and 900 °C) using steam as the gasification agent (7 bar, 0.3 kg/h). Gasification experiments were also perform with or without the use of calcium oxide. The gasification solid residue had its morphology analyzed by Scanning Electron Microscopy and X-Ray Diffraction. The gases produced were collect between 0-90 min, totaling 12 samples per experiment and analyzed by Gas Chromatography for the determination of their concentrations and energy potential. During the experiments, elevated temperatures demonstrated a better performance both in the gas yield as in its quality and composition. At 900 °C, syngas yields were 3.12 Nm³/kgFPR, with a hydrogen concentration of 104.0 gH2/100gFPR. It was observed that the higher heat value of the gas produced exceeds 30 GJ/day from the FPR used, which represents a power generation potential of around 8.5 MWh. This possibility of energy reuse can help to reduce energy demand bottlenecks, as well as the decrease of landfills.