AHrD [28

yx yx

From a practical standpoint, the advantages of this operating mode are:

• the column always operates at its maximum fractionating capacity;

• column operation is very easy: only a level controller is necessary, which keeps the reflux drum holdup at the specified value; no product switchovers are required;

• neither the yield nor the quality of the products is influenced by variations in the heating rate or interruption of the distillation.

However, it should also be observed that unavoidable uncertainties in the feed amount, feed composition and column hold-up would act in such a way as to prevent reaching the desired purity specifications for both products. In order to ensure that the more valuable product is recovered on specification, the hold-up of the vessel containing this product should be set somewhat smaller than requested theoretically; a conventional temperature controller may be cascaded to the reflux drum level controller in order to adjust the level setpoint online, according to the desired purity requirements. Another way to reduce (and even eliminate) the effect of the uncertainties is using a middle-vessel batch column.

For multicomponent separations, a cycling operation may be employed: the column is operated at total reflux until a steady state is approached; distillate is then taken as total draw-off for a short period of time; then, the operation is switched back to total reflux, and the operating cycle is repeated.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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