New Liquid Holdup Models in Both Preloading and Flooding Regions and a Flood Velocity Model to Identify Flooding for Sheet Metal Structured Packings

Abstract

Sheet metal structured packings are often employed in contacting columns because of their low pressure drops, high capacities, and high efficiencies. The liquid holdup on the packing sheets affects these attributes. Several researchers have developed various theoretical and empirical models for liquid holdup predictions. However, the majority of these models rely on packing-specific constants and detailed packing dimensions for model predictions. Such information is not readily available for many structured packings. The current work developed new liquid holdup models in preloading and flooding regions and a flood velocity model using the packing surface area and void fraction as the main model parameters. The performances of the newly developed and other literature models were evaluated using the liquid holdup and flood velocity database obtained from the open literature. The newly developed OkState models better predict the experimental data and capture the overall effects of flow rates, liquid properties, and packing geometries.

New insight and experimental study of ineffective void in hydrodynamic performance of countercurrent‐flow packing column

“…It is evident that an increase in viscosity corresponds to an increase in liquid holdup, with higher viscosity exerting a more pronounced effect. An elevated viscosity imposes greater resistance on liquid flow, impeding flow at lower rates within the packing 23 . Additionally, Figure 3 highlights that the 24 cp liquid exhibits an earlier flooding point than the 1 and 12 cp liquids, indicating that a higher viscosity reduces the operational range of the packing column.…”

“…These experimental results and models have been widely applied in developing packings, designing columns, and simulating processes (i.e., Aspen, Fluent, and computational fluid dynamic). However, several research results have indicated that model‐predicted values may exhibit notable deviations from actual observations 15–17 . For instance, the SRP model yields inaccurate predictions for liquid holdup in Sulzer Mellapak packings, with an average deviation of 30.7%, leading to substantial discrepancies in evaluating packing performance, designing columns, and simulating processes 15 …”

“…However, several research results have indicated that model-predicted values may exhibit notable deviations from actual observations. [15][16][17] For instance, the SRP model yields inaccurate predictions for liquid holdup in Sulzer Mellapak packings, with an average deviation of 30.7%, leading to substantial discrepancies in evaluating packing performance, designing columns, and simulating processes. 15 According to these models and experimental studies, the effective void fraction of the packing (ε À H) emerges as a pivotal factor in the modeling process and significantly influences the accuracy of hydrodynamic performance predictions.…”

“…[15][16][17] For instance, the SRP model yields inaccurate predictions for liquid holdup in Sulzer Mellapak packings, with an average deviation of 30.7%, leading to substantial discrepancies in evaluating packing performance, designing columns, and simulating processes. 15 According to these models and experimental studies, the effective void fraction of the packing (ε À H) emerges as a pivotal factor in the modeling process and significantly influences the accuracy of hydrodynamic performance predictions. This stems from the fact that the effective void fraction of the packing reflects the available liquid and gas retained within the packing, thus directly determining liquid holdup, pressure drop, effective interface area, and gas flooding velocity.…”