In distillation, how is the boilup ratio defined?

In distillation, how is the boilup ratio defined?

• A. The ratio of the vapor flow in the lowest stage to the bottoms product.
• B. The ratio of distillate to feed.
• C. The ratio of reflux to feed.
• D. The ratio of vapor to liquid in the reboiler.

Answer: (A)

In distillation, the boilup ratio tells you how vigorously the bottom of the column is boiled compared to what is withdrawn as bottoms. It is defined as the vapor flow rate in the lowest stage (the vapor coming from the reboiler into the bottom of the column) divided by the bottoms product flow rate. This ratio captures the relationship between the amount of vapor generated at the bottom and the amount of liquid that leaves as bottoms. A higher boilup ratio means more bottom vaporization per unit bottom product, which influences temperatures, stage compositions, and overall separation. The other measures correspond to different concepts: distillate-to-feed relates to the amount of product taken as overhead relative to feed, reflux-to-feed is the reflux ratio, and vapor-to-liquid in the reboiler describes the immediate flow in the reboiler but is not how boilup is conventionally defined.

In distillation, the boilup ratio tells you how vigorously the bottom of the column is boiled compared to what is withdrawn as bottoms. It is defined as the vapor flow rate in the lowest stage (the vapor coming from the reboiler into the bottom of the column) divided by the bottoms product flow rate. This ratio captures the relationship between the amount of vapor generated at the bottom and the amount of liquid that leaves as bottoms. A higher boilup ratio means more bottom vaporization per unit bottom product, which influences temperatures, stage compositions, and overall separation.

The other measures correspond to different concepts: distillate-to-feed relates to the amount of product taken as overhead relative to feed, reflux-to-feed is the reflux ratio, and vapor-to-liquid in the reboiler describes the immediate flow in the reboiler but is not how boilup is conventionally defined.