Precooling the feed of cryogenic distillation columns is achieved by using the cold distillate and bottoms streams. The distillate is typically removed from the top of the reflux drum as a vapor to reduce the condenser refrigeration heat duty. The bottoms stream is typically a liquid at a somewhat higher temperature than the distillate. The colder vapor distillate can only provide sensible heat removal. The warmer bottoms liquid stream can provide more heat removal because of vaporization.

The purpose of this paper is to demonstrate that the appropriate arrangement of the precooling heat exchangers depends on the column feed composition. If the feed contains little light key component, the bottoms stream is large and the feed can be easily precooled. If the feed contains little heavy key component, the bottoms stream is small and precooling the feed is more difficult.

低温蒸馏塔的进料是通过使用冷馏出物和塔底物流实现的。通常将馏出物作为蒸气从回流鼓的顶部除去，以减少冷凝器制冷热负荷。底部物流通常是温度略高于馏出物的液体。较冷的蒸气馏出液只能提供显着的除热效果。由于汽化，较热的底部液体流可提供更多的热量去除。

本文的目的是证明预冷热交换器的适当布置取决于塔进料的组成。如果进料中含有很少的轻质关键组分，则塔底料流较大，并且进料可以很容易地进行预冷却。如果进料中含有很少的重质关键成分，则塔底料流很小，预冷进料就更困难了。