Thermodynamic modeling and performance analysis on co-gasification of Chlorella vulgaris and petrochemical industrial sludge via Aspen plus combining with response surface methodology

The co-gasification process of Chlorella vulgaris (CV) and petrochemical industrial sludge (IS) was uncoupled and simulated by Aspen Plus. The co-gasification process was considered into drying, pyrolysis, partial oxidation, as well as reduction and reforming. Simulation results showed that, the interactions between IS and CV were found for the differences in CHO, and affected by the IS ratio and gasification temperature. Increasing the temperature could improve the CO content, and get optimal H₂ at 700 °C, while decrease CO₂ and CH₄ contents, thus lead to a higher LHV (lower heating value) of syngas, CGE (cold gas efficiency), and syngas content, CO selection. The higher S/IS-CV (steam to IS-CV blends ratio) value favored H₂ production but reduce CO content and CGE. As air equivalent ratio (ER) increased, the H₂ content constantly reduced, while CO varied slightly when the ER was lower than 0.10. After the ER value was higher than 0.10, CO reduced and thereby decreasing co-gasification performance. When the drying degree of feedstock increased, the CO content continuously increased, leading to better co-gasification performances. The RSM results showed that the significance factors in the interactions are ER and drying degree, S/IS-CV and ER, gasification temperature and ER, and gasification temperature and ER, respectively for CGE, LHV, C_syngas, and Sel_CO.