Mechanistic model for structured-packing-containing columns: Irrigated pressure drop, liquid holdup, and packing fractional wetted area

An implicit one-dimensional two-zone two-fluid mechanistic model was develo ped for the prediction of the irrigated two-phase pressure drop, the total liquid holdup, and the packing fractional wetted area in gas-liquid counter current columns containing structured packings and operated in the preloadi ng zone. The model was an offshoot of the well-known "single-slit" mechanis tic approach to cocurrent down-flow trickle-bed reactors. It mimicked the a ctual bed void by means of two hypothetical, recurrent, and geometrically s imilar inclined slits consisting of a dry slit and a wet slit. This mechani stic model required no single adjustable parameter and proved powerful in t he prediction of the column hydraulics under various operational conditions such as atmospheric scrubbing or high-pressure/temperature distillation co nditions. In this context, a collection of data relative to the irrigated p ressure drop, liquid holdup, and packing fractional wetted area, obtained u nder low/high pressure/temperature has been compiled from the literature fo r columns equipped with structured packings and operated below the loading point and under partial wetting. This databank provided pertinent informati on for successful validation of the model. The satisfactory results obtaine d highlight the breadth of applicability of the proposed approach, especial ly for new designs or for optimal rating of existing equipment.