Question

Which of the following transitions best exemplifies the temperature gradient (transition) that you want to maintain inside the fractional distillation column (Temperature at the bottom vs Temperature at the top of the column) in fractional distillation?

1. 125 - 25

2. 25 - 125

3. 25 - 75

4. 75 - 75

Answer 1

1. A temperature profile of 125 deg Celsius at the bottom and 25 deg Celsius at the top best exemplifies the temperature gradient to be maintained inside a distillation column. This is because the main objective of a distillation column is to separate the lighter components from the heavier ones. By keeping the top temperature low, we effectively condense most of the remaining heavier fraction in the overhead vapor phase and get a purer lighter component.

Similarly, maintaining a higher temperature at the bottom enables us to strip the heavier bottoms of any lighter components and get a purer bottoms product.

Keeping the same temperature profile throughout such as the 75-75 will not enable any separation of the feed.