How to Use the Absorption Data for Design and Scale‐Up of Packed Columns

Abstract

In this paperit is presented amodelforcalculationofmass transferindumped packed columns or in columns with orderly arranged packings,valid for systems, the mass transfer resistance of which is mainly located in the vapor resp. gas side. It can be applicated both for rectifications and absorptions. Basedonnumerous experiments thevalidityofthis model will beprovedand it is shown that absorption test results can be transferred on rectifications with an accuracy which is sufficient for industrial applications. Furthermore it is shown with metallic Pall ring packings how results received in test columns of various diameters can be applicated for pre-calculation of columns with industrial dimensions. To carry out this scaling-up aspecial diagram was developed.

Pressure Drop of Irrigated Random and Structured Packings

“…Equation (4)(5)(6)(7)(8)(9)(10) is also applicable in the range below the loading line and is based on turbulent gas flow. Billet's [5] experimental data as well as more recent data [13][14][15] can be verified more accurately by using the correlation developed by Billet and Maćkowiak [13][14][15].…”

“…(4)(5)(6)(7)(8)(9)(10)(11) constants in Table 4-2 Billet, Maćkowiak [13,15] Other methods, found in literature, for predicting the pressure drop in irrigated random packings are based on the model which is applicable to tube flow, Eq. , [52-54, 56, 64].…”

“…In rectification, the sum of the top pressure p T and the total pressure drop p gives the bottom pressure p W , which determines the bottom temperature t W . The bottom temperature, in turn, determines the effective temperature difference, at a given heating medium temperature, at which the reboiler in the distillation column must be operated.High pressure drops are likely to result in significant changes in the relative volatility along the column height, in particular in vacuum rectification processes with a high number of theoretical stages [5, 32], which means that the reflux ratios R, required to achieve the specified product purity, are considerably higher than in the case of low pressure drops p. Higher reflux ratios R lead to an increase in steam consumption and therefore in operating costs.The total pressure drop of the packing p at a known packing height H, the calculation of which was the topic of studies such as [13][14][15], is given by the product p = ( p/H)·H, in which the quotient p/H stands for the pressure drop per 1 m height of the packed bed.Based on the known pressure drop p/H and the specific pressure drop p/n t , Eq. (1-4) can be used to calculate the theoretical separation efficiency of the random or structured packing n t /H, and therefore the total height of the packed bed H, if the number of theoretical stages n t is known.…”

“…The total pressure drop of the packing p at a known packing height H, the calculation of which was the topic of studies such as [13][14][15], is given by the product p = ( p/H)·H, in which the quotient p/H stands for the pressure drop per 1 m height of the packed bed.…”

Distillation, 2. Equipment

“…Liquid hold-up is a decisive parameter of two-phase flow in packed beds. Typical values of the hold-up h L , defined as ratio of liquid volume to packing volume, are presented in Figure 21 [17]. Here, the experimental values of the hold-up h L are plotted versus the pressure drop in the packed bed Dp irr =ðHÁr L ÁgÞ.…”