Co-gasification of glycerol and linear low density polyethylene (LLDPE) for syngas production: A thermodynamic targeting approach

The co-gasification of different wastes for syngas production is a promising technology as it reduces pressure on waste management and promotes waste valorization. This paper considered the steam co-gasification of glycerol and linear low density polyethylene plastic (LLDPE) waste to produce syngas. To achieve this, a graphical targeting approach based on carbon, hydrogen, oxygen (CHO) ternary diagrams was used to determine the impact of different operating parameters (pressure, temperature and LLDPE content) on syngas composition. It was determined that an increase in pressure decreased H₂ and CO content but increased the content of CH₄, CO₂ and H₂O. It was also determined that increasing the LLDPE content increased H₂ and CH₄ concentration, but decreased CO, CO₂ and H₂O concentration. The synergistic interaction of the feedstocks on the syngas ratio and lower heating value (LHV) was also determined. Results revealed that increasing the pressure decreased the synergistic effect. Furthermore, an Aspen Plus simulation was performed at different steam to feedstock ratios (SFR) and at 1000 K and 1 bar. The highest positive extent of synergy in terms of LHV, syngas yield (SY), carbon conversion efficiency (CCE) and cold gas efficiency (CGE) of 8.29 %, 21.51 %, 23.38 % and 23.81 % was achieved at LLDPE content of 50 % and SFR of 0.8, 1, 0.8 and 0.8 respectively. At these operating conditions the value of LHV, SY, CCE and CGE was found to 11.63 MJ/Nm³, 3.22 Nm³/kg, 95 % and 64 % respectively.