Effect of Feedstock Blends and Equivalence Ratio on the Thermal Arc Plasma Assisted Co-Gasification of Biomass and Plastic using Air-Blown Downdraft Reactor

Abstract

Plastic waste is known to cause an emerging environmental pollution, posing risks to both terrestrial and aquatic ecosystems. Co-gasification method is an alternative way to reduce municipal solid waste and plastic waste by converting it into useful gas fuel energy. The present study used empty fruit bunch biomass (EFB), plastic waste of low-density polyethylene (LDPE) and Polyethylene terephthalate (PET) as a feedstock for thermochemical conversion process into syngas fuel energy via plasma co-gasification method. The effect of multiple feedstocks mixture between biomass and plastic and equivalence ratio on the compositions of produced syngas, high heating value (HHV), lower heating value (LHV), cold gas efficiency (CGE) and carbon conversion efficiency (CCE) were critically investigated. A reactor of air-blown downdraft arrangement was used in these experiments. The gasifying agent flow rate of air was set at the frequency range of 10 to 22Hz to achieve equivalence ratio between 0.15 to 0.30. The blending ratio (BR) between biomass and plastic (EFB:Plastic) were set as E90:P10, E80:P20 and E70:P30. The results indicate that H₂ and CO composition is typically decrease as ER increase for the mixture of EFB and LDPE. In contrast, the composition of H₂ and CO is generally increase as ER increases. However, the maximum value of H₂ and CO is dominated by the mixture of EFB and LDPE at any blending ratio and lower ER condition. This is due to the higher element of H, C and O in the raw material of EFB and LDPE compared to PET. This study is crucial in understanding the synergistic effect of co-gasification assisted with plasma reaction between biomass and plastic waste.