Modelling and statistical analysis of plastic biomass mixture co-gasification

In this work, an Aspen Plus model was developed to study the plastic/biomass co-gasification thermodynamically. Tar inclusion and temperature restricted equilibrium approach were applied for model modification. Using different gasifying agents, it was found that steam co-gasification is superior to air and oxygen-gasified processes in terms of gas composition and lower heating value (LHV). The use of an oxygen/steam mixture enhances H ₂ production if the steam to fuel ratio (S/F) is kept low. The modelling results were integrated with Response Surface Methodology to study the impacts of temperature (T), steam to fuel ratio (S/F), and plastic to biomass ratio (P/B) and their interactions within the steam co-gasification process. It was found that T and S/F, and their interaction, are the most influential parameters. Increasing the T, S/F, and P/B was favourable for enhancing H₂ production, gas yield (GY), and carbon conversion efficiency (CCE), while CO content and LHV can be negatively affected. Using ANOVA results, empirical correlations were derived for estimating the responses (H₂, CO, CO₂, CH₄, LHV, GY, and CCE). The optimum condition obtained using the desirability function (DF) approach was T = 921 °C, S/F = 1.186, and P/B = 74.99, at which the overall desirability function was found to be DF = 0.9.