Equilibrium model analysis of waste plastics gasification using CO₂ and steam

Utilization of carbon dioxide (CO₂) in thermochemical treatment of waste plastics may significantly help to improve CO₂ recycling, thus simultaneously curtailing dioxins/furans and CO₂ emissions. Although CO₂ is not such an effective gasifying agent as steam, a few investigations have explored the utilization of CO₂ in conjunction with steam to achieve somewhat higher carbon conversion. This work presents a comparative evaluation study of CO₂ and steam gasification of a typical post-consumer waste plastics mixture using an Aspen Plus equilibrium model. The effect of flow rate of gasifying medium (CO₂ and/or steam) and gasification temperature on product gas composition, carbon conversion, and cold gas efficiency has been analyzed. Simulation results demonstrate that CO₂ can serve as a potential gasifying agent for waste plastics gasification. The resulting product gas was rich in CO whereas CO₂–steam blends yield a wider H₂/CO ratio, thus extending the applications of the product gas.