Distillation simple takeover

One hundred moles of a 50-50 mixture of benzene and toluene are to be batch distilled in a simple takeover process. The relative volatility of benzene with respect to toluene is 2.5. The distillation is to proceed until the mole fraction of benzene in the stillpot is 0.20. How many moles remain in the stillpot at the end of the distillation ... 

This type of distillation involves Teeds and products that are not ensily described in terms or identifiable components. Instead, the feed and product sires ms are characterized in terms of their boiling ranges, measurements diet can be made in simple takeover stills of die typa specified by die American Society for... 

FIGURE 5.5-9 Rayleigh, or simple takeover, belch distillation. 

The foregoing eqontions apply to simple takeover batch distillation, with no reflux. If a column is installed abuve the stillpot and provision is made to return a portion of the condensed overhead vapor to the column as reflux, it is possible to obtain a much better separation. As an extreme case, near-total reflux is used to get the best possible separation, without regard to the length of time required for die revalorization of the reflux. Uader such a condition, the Fenske relationship [Eq. (5.3-28)] may be ased to relate the siillpot vapor composition to that of the vapor passing over to the condenser ... 

Early distillations were of the batch, takeover type, sometimes called simple distillation or differential distillation. A charge of liquid mixture is vaporized from a still, or stillpot, by heat addition, and the product vapor is condensed into one or more fractions. Thus the term fractional distillation, or fractionation, has become associated with any distillation operation designed to obtain defined or specified constituent fractions. 

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