Efficiency, Murphree plate

This is the one case where the overall column efficiency can be related analytically to the Murphree plate efficiency, so that the actual number of plates is calculable by dividing the number of theoretical plates through equation 86 ... [Pg.42]

Most distillation systems ia commercial columns have Murphree plate efficiencies of 70% or higher. Lower efficiencies are found under system conditions of a high slope of the equiHbrium curve (Fig. lb), of high Hquid viscosity, and of large molecules having characteristically low diffusion coefficients. FiaaHy, most experimental efficiencies have been for biaary systems where by definition the efficiency of one component is equal to that of the other component. For multicomponent systems it is possible for each component to have a different efficiency. Practice has been to use a pseudo-biaary approach involving the two key components. However, a theory for multicomponent efficiency prediction has been developed (66,67) and is amenable to computational analysis. [Pg.170]

Ejfects of Gas and Liquid Mixing As noted previously, it is necessary in most instances to convert point efficiency E g to Murphree plate efficiency E, ,. This is true because of incomplete mixing only in small laboratoiy or pilot-plant columns, under special conditions, is the assumption E g = E, , likely to be valid. For a crossflow plate with no hquid mixing there is plug flow of hquid. For this condition of liquid flow, Lewis [Ind. Eng. Chem., 28, 399 (1936)] analyzed effects of gas mixing on efficiency. He considered three cases ... [Pg.1382]

Murphree plate efficiency (Murphree, 1925), defined in terms of the vapour compositions by ... [Pg.547]

In some methods, the Murphree plate efficiencies can be incorporated into the procedure for calculating the number of stages and the number of real stages determined directly. [Pg.548]

For the idealised situation where the operating and equilibrium lines are straight, the overall column efficiency and the Murphree plate efficiency are related by an equation derived by Lewis (1936) ... [Pg.548]

Kmv = Murphree plate efficiency, E0 = Overall column efficiency. ... [Pg.549]

The AIChE method, and that of Van Winkle, predict the dry Murphree plate efficiency. In operation some liquid droplets will be entrained and carried up the column by the vapour flow, and this will reduce the actual, operating, efficiency. [Pg.556]

A mixture of alcohol and water containing 0.45 mole fraction of alcohol is to be continuously distilled in a column to give a top product of 0.825 mole fraction alcohol and a liquor at the bottom containing 0.05 mole fraction alcohol. How many theoretical plates are required if the reflux ratio used is 3 Indicate on a diagram what is meant by the Murphree plate efficiency. [Pg.132]

Murphree plate efficiency is discussed in the solution to Problem 11.9. [Pg.132]

Murphree plate efficiency, 8 767-768 Murphree stage efficiency, 70 758 Murphree vapor plate efficiency, 7 84, 87-89... [Pg.607]

How many theoretical plates are required if the reflux ratio used is 3 Indicate on a diagram what is meant by the Murphree plate efficiency. [Pg.1166]

Multicomponent efficiency profiles. Figure 7.11 (198,199) shows typical variations of Murphree plate efficiency for a ternary system made up of a light key (LK) component, a heavy key (HK) component, and a heavy nonkey (HNK) component (benzene, toluene, and m-xylene, respectively). On the basis of experimental data, point efficiency was assumed the same for all components throughout the column. [Pg.398]

Three hinds of plate efficiencies may be used for expressing the relationship between the performance of theoretical and actual stages. They are (1) overall column efficiency or overall plate efficiency, (2) Murphree plate efficiency, and (3) point efficiency or local efficiency. [Pg.661]

In multicomponent mass-transfer operations, the assumption is usually made that the same plate efficiency applies to all components being separated. The overall column efficiency is then considered in terms of the key components, and the same efficiency is assumed for the lighter and heavier components. This assumption is not necessarily correct because of the different properties of the components. More exact results can be obtained by using Murphree plate efficiencies and accounting for the difference in efficiencies. [Pg.663]

Stage Efficiency The use of the Murphree plate efficiency is particularly convenient on y-x diagrams. The Murphree efficiency is defined for the vapor phase as... [Pg.25]

Aerodynamic diameter of a real median size particle Diffusion coefficient Sauter mean diameter Volume mean diameter Entrainment, mass liquid/mass gas Plate or stage efficiency, fractional Power dissipation per mass Murphree plate efficiency, with entrainment, gas concentrations, fractional... [Pg.1172]

Overall column efficiency, fractional Overall point efficiency, gas concentrations, fractional Murphree plate efficiency, gas concentrations, fractional Eractional approach to flood E-factor for gas loading Elow parameter Gravitational constant Conversion factor... [Pg.1172]

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