Equilibrium stage based model of a vegetable oil based wet packed bed scrubbing system for removing producer gas tar compounds

• Equilibrium stage based absorption model was developed using a split (φ/γ) approach.
• PENG–ROB EOS and NRTL models were used to predict thermodynamic properties.
• The missing binary interaction parameters of NRTL were predicted using UNIFAC.
• Model predicted best fits with experimental data at solvent temperature of 30 °C.
• Packing constants Ch = 2.52 and CP,0 = 2.93 were found to predict pressure drop.

This study was aimed to develop and validate equilibrium stage based absorption model to investigate the removal of model producer gas tar compounds using vegetable oil as a solvent. The absorption model was developed using split (φ/γ) approach and a “RadFrac” block in Aspen Plus™. The model used Peng–Robinson equation of state (EOS) and non-random two-liquid (NRTL) activity coefficient model to predict the fugacity coefficients (φ) for vapor phase and activity coefficients (γ) for liquid phase. The developed model was validated using the extreme conditions of the experimental test range. The model predictions showed best fits with the experimental data within 6% for benzene, 4% for toluene, and 2% for ethylbenzene at the solvent temperature of 30 °C. Packing specific constants of Billet and Schultes (1999) correlation (Ch = 2.52 and CP,0 = 2.93) were found experimentally. These constants can be used to predict pressure drop across the column for vegetable oil based wet packed bed scrubbing systems. The average deviation of predicted pressure drop across the column compared to experimental data was within 5%. The developed absorption model and packing specific constants would be beneficial in the design, optimization, and economic evaluation of vegetable oil based wet packed bed scrubbing systems.