Prediction of plate efficiency

Some typical values of plate efficiency for a range of systems are given in Table 11.1. More extensive compilations of experimental data are given by Vital et al. (1984) and Kister (1992). 

and overall column, efficiencies will normally be between 30 per cent and 70 per cent, and as a rough guide a figure of 50 per cent can be assumed for preliminary designs. 

Kmv = Murphree plate efficiency, E0 = Overall column efficiency.  

Efficiencies will be lower for vacuum distillations, as low weir heights are used to keep the pressure drop small (see Section 11.10.4). 

The prediction methods given in the following sections, and those available in the open literature, are invariably restricted to binary systems. It is clear that in a binary system the efficiency obtained for each component must be the same. This is not so for a multicomponent system the heavier components will usually exhibit lower efficiencies than the lighter components. 

The prediction methods given in the following sections, and those available in the open literature, are invariably restricted to binary systems. It is clear that in a binary system 

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Davies et al. (27) also extended their studies to distillation of formalin solutions, that is the analysis of a distillation coluOTi involving reactions of formaldehyde with water and methanol. The problem was complicated by the estimation of equilibrium data for a system of five-components of which one (hemiformal) does not exist in a pure state. Although good agreement is claimed between theory and experiment, some of the assumptions are rather doubtful, e.g. the use of the A.I.Ch.E. method for prediction of plate efficiencies. 

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