Co-gasification of Crude Glycerol and Plastic Waste using Air/Steam Mixtures: A Modelling Approach

This study evaluated the air/steam co-gasification of crude glycerol (CG) and linear low density polyethylene (LLDPE). It was demonstrated that operating the process using air or a mixture of air and steam has significant implications for carbon conversion efficiency (CCE), cold gas efficiency (CGE), lower heating value (LHV) gasifier output temperature and syngas concentration. The CCE reached a maximum value of 100% at equivalence ratio (ER) of 0.3 for 25% LLDPE and an ER of 0.35 for 75% LLDPE when air was used. When steam was introduced in the gasifier at a fixed rate (SFR =0.5), the CCE of 100% was maximised at ER of 0.25 for 25% LLDPE and 0.3 for 75% LLDPE content. An increase in the steam to feedstock ratio (SFR) did not alter the CCE for 25% LLDPE at a constant ER, but for that of 75% LLDPE, a CCE was maximized at an SFR of 0.25. In the case of CGE, a maximum value of 79.24% and 78.12% was reached at ER of 0.3 and 0.35 for 25% LLDPE and 75% LLDPE respectively when pure air was used. Keeping the SFR constant, the CGE slightly increased to 81.33 and 81.45% at ER of 0.25 and 0.3, respectively for 25% LLDPE and 75% LLDPE. The LLDPE content did not significantly alter the syngas LHV at a fixed ER or SFR. The gasifier temperature increased with an increase in ER but decreased when steam was fed into the gasifier. Furthermore, the syngas ratio (H2:CO) achieved in this study can be useful for the synthesis of methanol and dimethyl ether.