A theoretical study on municipal solid waste plasma gasification

Gasification is an innovative and effective process which reduces the amount of waste produced by society and affords a synthetic gas with diverse applicability. In this plasma gasification study at high temperatures, a previously developed Aspen Plus model was used for municipal solid waste (MSW). The study is focused on the behavior of the equivalence ratio (ER), steam to MSW (S/MSW) ratio and gasification temperature (T), as a function of three gasification agents (air, O₂ and steam), assessing the final syngas composition. The model was validated with results from literature. The highest hydrogen yield reached 64% (molar fraction), when steam was used as gasification agent, lower values corresponding to O₂ utilization. Instead, a CO-enriched syngas was achieved under O₂ atmosphere (58%). Enhanced lower heating value (LHV) was obtained for the syngas produced when ER = 1, under oxygen atmosphere at 1500 °C (13 MJ/Nm³). This is due to the formation of CO, promoted by O₂, which constitutes an important factor in enhancing syngas LHV. Tar presence in the gasification process normally implies significant complications, but in this study, no problems were noticed since gasification occurred at higher temperatures.