Energy recovery from waste glycerol by utilizing thermal water vapor plasma

Glycerol, considered as a waste feedstock resulting from biodiesel production, has received much attention in recent years due to its properties, which offer to recover energy. The aim of this study was to investigate the use of a thermal water vapor plasma for waste (crude) glycerol conversion to synthesis gas, or syngas (H₂ + CO). In parallel of crude glycerol, a pure glycerol (99.5%) was used as a reference material in order to compare the concentrations of the formed product gas. A direct current (DC) arc plasma torch stabilized by a mixture of argon/water vapor was utilized for the effective glycerol conversion to hydrogen-rich synthesis gas. It was found that after waste glycerol treatment, the main reaction products were gases with corresponding concentrations of H₂ 50.7%, CO 23.53%, CO₂ 11.45%, and CH₄ 3.82%, and traces of C₂H₂ and C₂H₆, which concentrations were below 0.5%. The comparable concentrations of the formed gas products were obtained after pure glycerol conversion-H₂ 46.4%, CO 26.25%, CO₂ 11.3%, and CH₄ 4.7%. The use of thermal water vapor plasma producing synthesis gas is an effective method to recover energy from both crude and pure glycerol. The performance of the glycerol conversion system was defined in terms of the produced gas yield, the carbon conversion efficiency, the cold gas efficiency, and the specific energy requirements.