Prediction of pressure drop in liquid–liquid pulsed packed extraction countercurrent columns

• Pressure drop is seriously affected by continuous phase flow rate and pulsation intensity.
• The effect of the dispersed phase flow rate on pressure drop is less than other variables.
• Modified Khan and Varma eq. is suggested to calculate the pressure drop in a pulsed packed liquid–liquid extraction column.
• Average absolute relative error (AARE) of the modified Khan and Varma eq. to calculate pressure drop is up to 4.0%.

In this study, the two-phase pressure drop has been investigated using three different liquid systems of water–butyl acetate, water–toluene and water–kerosene, with different interfacial tension, in the absence of mass transfer in a pilot plant pulsed packed column, with ceramic packs of Raschig ring type of 0.63 cm in diameter. The effects of operational parameters, such as dispersed and continuous phases flow rates and pulsation intensity, on two-phase pressure drop away from flooding point were studied, and it was found out that pressure drop is seriously affected by continuous and dispersed phases flow rate and pulsation intensity, on the other hand, with an increase in one of the operating parameters pressure drop will also be increased. Finally, using correlations presented to predict pressure drop in gas–liquid form in packed columns, the modified Khan and Varma correlation was suggested to calculate the pressure drop in the pulsed packed liquid–liquid extraction column, which shows a good agreement with an Average Absolute Relative Error (AARE) of 4.2% for their optimized constant. Due to good agreement of the experimental data with results gained by the modified Khan and Varma correlation, it is also recommended, in addition to predict pressure drop and with reverse calculations, to assess the dispersed phase hold-up in a pulsed packed column.