Efficiency in distillation

AiCbE Researcb Committee, Tray Efficiency in Distillation Columns, final report. University of Delaware, Newark, 1958. 

There has been considerable speculation regarding the depth of packing that could be installed before liquid redistribution is required. Silvey and Keller found no loss of efficiency in distillation with 18-ft deep beds of 1 A-in. ceramic... 

From the standpoint of corrosion protection, a slight amount of mineral scale formation—if the thickness can be controlled—is desirable. This helps to explain why, in some cases, sea water is found to be less corrosive than a brine of sodium chloride with the same salinity. However, in applications where heat is being transferred across the metal wall, the presence of scale markedly affects the efficiency. In distillation units, a method of corrosion control based on intentional mineral-scale formation would thus lead to greater fuel consumption. 

Weir Height Taller weirs raise the liquid level on the tray in the froth and emulsion regimes. This increases interfacial area and vapor contact time, which should theoretically enhance efficiency. In the spray regime, weir height affects neither liquid level nor efficiency. In distillation systems, the improvement of tray efficiency due to taller weirs is small, often marginal. 

AIChE Research Committee, Tray Efficiencies in Distillation Columns, Final report from the University of Delaware, 1958. 

The calculated point efficiency must be converted to overall column efficiency, which will lower its value and make it closer to the O Connell prediction. The calculated value of Eog is slightly higher than obtained experimentally (Eog = 0.83-0.92) at the University of Delaware for bubblecap trays (Annual Progress Report of Research Committee, Tray Efficiencies in Distillation Columns, AIChE, New York, 1955). 

Aittamaa, J., Estimating Multicomponent Plate Efficiencies in Distillation, Kem.-Kemi, 8, 295-300,... 

J. A. Gerster, A. B. Hill, M. N. Hochgraf, and D. N. Robinson, Tray Efficiencies in Distillation Columns—Final Report from the University of Delaware to the AIChE Committee, 345 East 47 Street, New York, American Institute of Chemical Engineers, 1958. 

Schreiner, H., Plate Efficiency in Distillation Columns with Demisters, I. Chem. E. Symp. Ser. 73, 1982, p. L23. 

The results of simulation models are strongly affected by the particular assumptions made in the plant model and by the model parameters. This is the reason why these parameters should be fitted to reliable data describing simplified systems, for example, binary mixtures. Regressing parameters to observations on the complex target system is usually not feasible, as the influence of the assumptions made on the performance of the equipment (e.g., tray efficiency in distillation) is not sufficiently isolated from the influence of the model parameters. The experimental data for the isolated subsystems are the key for a successful process model. They contain all the information about the process model, the model parameters are only a representation. If new data become available, the model can be upgraded by extending the database and perform a new regression. 

Holland CD, McMahon KS (1970) Comparison of vaporization efficiencies with Murphree-type efficiencies in distillation-I. Chem Eng Sci 25(3) 431 36... 

Here 2A,eff,2,z = A,eft,2,z- This equation is the basis of the AIChE model (AIChE, 1958) for tray efficiency in distillation. 

Siiess Ph, Meier W. Optiflow-Improved efficiency in distillation and absorption columns. Technical information - Separation Columns- by Sulzer Chemtech, Winterthur... 

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