The ternary mixture can be separated into three relatively pure fractions by the use of varying reflux to obtain high overhead concentrations, with intermediate slop cuts being taken during the transition between components.

5.2 New Design—A Case History

Most of the concepts discussed to this point are also used in the design of new distillation systems. The material that follows is based on the design of such a system that operated successfully over the life of the plant in which it was situated.

The XYZ Chemical Company is designing a plant to produce 3,300,000 lb per year of a new product called "R." R is to be purified by separating it from light and heavy impurities by vacuum distillation in a batch still. Because the new plant is expected to be able to operate 330 days per year, the distillation system must be able to separate 10,000 lb per day of R from its impurities. As received from the upstream processing facilities, crude R contains impurities C, P, and W.

The XYZ research department has thoroughly investigated the manufacture of R, and the final report on their investigation presents the following information on R, C, P, and W.

The molecular weights, freezing points, and normal boiling points of pure R, C, P, and W have been determined, as have the constants for vapor pressure (VP), expressed as

where VP is in mmHg, and T is in kelvin. This information is summarized below.

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