Pressure drop in packed column

Abstract

Packed bed columns are an integral part of several traditional chemical engineering processes and find applications in new environmental engineering technologies. The pressure drop, and hence the energy loss is an important consideration in their design and operation. There are many different proposed formulas in literature to calculate the pressure drop for different particle size and varying flow rates. The objective was to compare the two setups for data collection and then to find out which equation proposed in literature is the best fit for the measured data.

This project studied the pressure drop over a wide range of flow rates with six different packing materials of different diameter, one at a time, using a manometer and later a transducer setup. This included four sets of natural gravel and two sets of spherical glass marbles. It was found that the transducer and manometer both give good readings for high flow rate. However, the transducer is able to get data for very low flow rate which the manometer is not.

The six data sets from the transducer were then compared to the Ergun equation in its original form. The author also suggested different values of Ergun’s empirical constants that better fit the measure data. The author next compared the transducer data with Cheng’s formula and Eisfeld & Schnitzlein’s formula. It was found that the Eisfeld & Schnitzlein formula systematically underestimates the pressure drop. Cheng’s formula works well for low and intermediate flow but slightly overestimates the pressure drop for very high flow rates. The author offered possible explanations for these observations and made recommendations for future researchers studying pressure drop in packed columns.