Plate efficiency overall

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]

EmpiricalEfficieny Prediction Methods. Numerous empirical methods for predicting plate efficiency have been proposed. Probably the most widely used method correlates overall column efficiency as a function of feed viscosity and relative volatiHty (64). A statistical correlation of efficiency and system variables has been developed from numerous plate efficiency data (65). [Pg.170]

An alternative to determining packed height is through the use of an empirical term, height equivalent to a theoretical plate (HETP). This term can be measured in a fashion similar to that used for the overall plate efficiency of a column (eq. 44) ... [Pg.173]

Tray Efficiencies in Plate Absorbers and Strippers Compn-tations of the nnmber of theoretical plates N assnme that the hqnia on each plate is completely mixed and that the vapor leaving the plate is in eqnihbrinm with the liqnid. In actnal practice a condition of complete eqnihbrinm cannot exist since interphase mass transfer reqnires a finite driving-force difference. This leads to the definition of an overall plate efficiency... [Pg.1358]

Mols of distillate or overhead product, lb mols/hr or batch distillation, mols Mols component, i, in distillate Vaporization efficiency of steam distillation Overall column efficiency Overall tray efficiency Eqg = Murphree point efficiency, fraction Murphree plate/tray efficiency, = E ... [Pg.102]

Overall column efficiency. This is sometimes confusingly referred to as the overall plate efficiency. [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]

Plate, 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. [Pg.548]

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

Drickamer, H. G. and J. B. Bradford, Overall Plate Efficiency of Commercial Hydrocarbon Fractionating Columns, Trans. AIChE 39, 319,1943. [Pg.143]

It is desired to concentrate a mixture of ethyl alcohol and water from 40 mole per cent to 70 mole per cent alcohol. A continuous fractionating column, 1.2 m in diameter with 10 plates is available. It is known that the optimum superficial vapour velocity in the column at atmosphere pressure is 1 m/s, giving an overall plate efficiency of 50 per cent. [Pg.159]

A thirty-plate bubble-cap column is to be used to remove n-pentane from a solvent oil by means of steam stripping. The inlet oil contains 6 kmol of n-pentane/100 kmol of pure oil and it is desired to reduce the solute content of 0.1 kmol/100 kmol of solvent. Assuming isothermal operation and an overall plate efficiency of 30 per cent, what is the specific steam consumption, that is kmol of steam required/kmol of solvent oil treated, and the ratio of the specific and minimum steam consumptions. How many plates would be required if this ratio is 2.0 ... [Pg.180]

Drickamer, H. G. and Bradford, J. R. Trans. Am. Inst. Chem. Eng. 39 (1943) 319. Overall plate efficiency of commercial hydrocarbon fractionating columns as a function of viscosity. [Pg.651]

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]

The required number of actual plates, Ap, is larger than the number of theoretical plates, App, because it would take an infinite contacting time at each stage to establish equilibrium. The ratio Aj Ap is called the overall column efficiency. This parameter is difficult to predict from theoretical considerations, however, or to correct for new systems and operating conditions. It is therefore customary to characterize the single plate by the so-called Alurphree vapor plate efficiency, Ey (98) ... [Pg.40]

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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