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Applying Simpson's rule

Area = ^ [28.6 + 4(16.0 + 13.8 + 13.4) + 2(14.3 + 13.6) + 13.2]

= 3.61 V = W0(xd - *o)(Area) « 100 (0.95 - 0.50)(3.61) = 162 moles vapor

As noted under the discussion of the constant reflux ratio case, the boil-up rate of an existing distillation system should be well known, so use of that boil-up rate with the vapor quantity just calculated will yield the time required for the separation of the new system. Note that this value of time refers only to the distillation itself: charging time, heat-up time, cooling time and clean-out time are not included.

The results obtained in all of the examples except 5.2 are sum-narized in Table 5.2. Table 5.2 also contains the results of other calculations, the percentage of the benzene originally in the still which was recovered in the overhead and the heat required to obtain the separation.

Even a brief review of Table 5.2 suggests a number of conclusions:

L Simple distillation a. Gives highest percentage recovery of benzene in the product,

TABLE 5.2 Comparing Results for Simple Distillation, Constant Reflux Ratio, and Varying Reflux Ratio Batch Distillation, Examples 5.1, 5.3,5.4_

Stl" Receiver Benzene re- Vapor re- Heat re.

Mol. Mol. covery Benzene quired, quired,

Molee frac. Moles frac. (receiver), % recovery, lb moles Btu

TABLE 5.2 Comparing Results for Simple Distillation, Constant Reflux Ratio, and Varying Reflux Ratio Batch Distillation, Examples 5.1, 5.3,5.4_

Stl" Receiver Benzene re- Vapor re- Heat re.

Mol. Mol. covery Benzene quired, quired,

Molee frac. Moles frac. (receiver), % recovery, lb moles Btu

Simple distilla

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