Equilibrium model analysis of waste plastics gasification using CO2 and steam

Abstract

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.