a n d J . M a t k o w i a k " * ; Ruhr-UnivenigBochum, West Gennany
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.
. I n t r o d u c t i o n
In practice, distillation is resorted too for separating of substances with very different physical properties. Although economic aspects favour expandng the field of application for packed columns in rectification, this often presents problems in scaling up and in applying data obtained by simulating rectification with aidwater systems. The opinion still holds sway in many quarters that efficiencies determined with an aidwater system applr to only a limited extent or do not apply at all to distillation ' .
The problem also concerns plate columns in cases where only limited success can be gained by introducing corrections to increase the usefulness of information acquired from simulation experiments. It is a question that Zuidemegand vander Meer' and Hoppe' had already studied in the early 1970s. Andit was only afew years ago that attention was directed to the same problem in packed columns, and valuable contributions towards solving it have been made by Zuidemed and by Zech and Menmann".
Nevertheless, no reports have yet been publishedin which success can be claimed in applying the results of measurements on aidwater systems quantitatively to distillation. Yet efforts along these lines must be pursed, because experiments with aidwater systems are undoubtedly cheaper and easier to carry out than rectification experiments particularly in columns with very large diameters. This article discusses the possibility of applying simulation data acquired with an aidwater system in a packed column to rectification. It also deals with the prediction of pressure drop Ap/H in the irrigated bed and the efficiency n,/H in columns with or without maldistribution. The equations that are thus drawn up have been confirmed by experimental data.
. T w o -P h a s e F l o w i n P a c k e d C o l u m n s
InFig. 1, whichisvalid foranair/watersystem, the pressure drop Ap/H is shown as a function of the air velocity uv with the liquid load uL as parameter. The various flow conditions are characterized by the appropriate sections of the curves. At loads equal to or less than 65 O/o of the maximum, the pres-