Experimental investigation of pressure drop in structured packings

Several studies have been performed to measure pressure drop in packed towers, however, most of them have focused on distillation and random packings and the correlations obtained may not be directly applicable to reactive absorption. In this paper, results from a study of pressure drop in 3 different structured packings; Mellapak 2X from Sulzer, Koch-Glitsch Flexipac 2Y HC, and Montz-Pak B1-250M, are presented. The fluid systems tested were: air/water, air/ aqueous sugar solutions with liquid viscosities from 2.5 to 12 cP and finally air/30 wt% MEA. The column used had a 5 m packing height with an inner diameter of 0.5 m. Pressure drop across the packing height was obtained as function of gas and liquid flow rate both as total pressure drop and as pressure change along the packing. A slight influence of viscosity on pressure drop and flooding point was found. The experimental results were compared with estimates made using the software packages provided by the various suppliers for their own packings. Comparisons between estimated and experimental results showed that the selected software in general gives reliable predictions of pressure drop up to an F-factor of about 3 Pa0.5, but that deviations may occur even for lower F-factors at high liquid loads. For low liquid loads (<10 m3/m2h) the software estimations are good in the whole range of measurements (F-factor <4.5–5 Pa0.5). For reactive systems at all liquid loads there is hardly any change at all for the Flexipac 2Y HC and B1-250 M. For the Mellapak 2X the effect of the reactive system is significant for high liquid loads.

► New pressure drop data on three modern packings where little data are published.
► Data extends to high gas flow rates above basis for commercial software.
► Data and vendor correlations show discrepancies at the high gas superficial velocities.
► Pressure drops for high viscosity solutions and reactive absorbent systems.