Overall plate fractional efficiency

To determine the actual number of plates required, divide the result in step 2 by the overall plate fractional efficiency, typically denoted by E(y Values can range from 0.4 to 0.8. The actual number of plates can be calculated from... 

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 ... 

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

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. 

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. 

Drickamer, H.G. Bradford, J.B. Overall plate efficiency of commercial hydrocarbon fractionating towers. Trans. AIChE 1943, 39, 319. 

This fraction can be measured along the curved saturated extract line. It should be stressed that the resulting number of stages, 2.2, is only approximate. The fractional number of stages is useful when the actual stages are not equilibrium stages. Thus, if a sieve-plate column with an overall plate efficiency of 25% were being used, the actual number of plates required would be... 

FIG. 14-37 Overall column efficiency of 25-mm Oldersbaw column compared with point efficiency of 1,22-m-diameter-sieve sieve-plate column of Fractionation Research, Inc, System = cyclohexane-n-heptane, [(Fair, Null, and Bolles, Ind, Eng, Chem, Process Des, Dev, 22, 53 (i.982),]... 

While ethyl chloride is one of the least toxic of all chlorinated hydrocarbons, CE is a toxic pollutant. The off-gas from the reactor is scrubbed with water in two absoiption columns. The first column is intended to recover the majority of unreacted ethanol, hydrogen chloride, and CE. The second scrubber purifies the product fiom traces of unreacted materials and acts as a back-up column in case the first scrubber is out of operation. Each scrubber contains two sieve plates and has an overall column efficiency of 65% (i.e., NTP = 1.3). Following the scrubber, ethyl chloride is finished and sold. The aqueous streams leaving the scrubbers are mixed and recycled to the reactor. A fraction of the CE recycled to the reactor is reduced to ethyl chloride. This side reaction will be called the reduction reaction. The rate of CE depletion in the reactor due to this reaction can be approximated by the following pseudo first order expression ... 

The HETP (Height Equivalent to a Theoretical Plate (stage or plate)) is the tray spacing divided by the fractional overall tray efficiency [82]. The transfer unit concept has been useful for generalized correlations [89]. Because packed towers operate with continuously changing compositions through the packed height, the concept... 

E Plate or stage efficiency, fractional -/- -/- Dog Height of an overall transfer m ft... 

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... 

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