In distillation design, what is the reflux ratio?

In distillation design, what is the reflux ratio?

• A. The ratio of vapor to liquid in the condenser.
• B. The ratio of distillate to feed rate.
• C. The ratio of feed to distillate.
• D. The ratio of liquid returned to the column to the distillate taken off.

Answer: (D)

Reflux ratio measures how aggressively you recycle liquid back into the column relative to the amount you withdraw as product. After the condenser, some liquid becomes the distillate and some is sent back down as reflux. The reflux ratio is defined as the flow rate of that reflux divided by the distillate flow rate. So the description that matches this is the ratio of the liquid returned to the column to the distillate taken off. This ratio controls separation quality: higher reflux improves purity and allows more efficient separation (at the cost of more energy and larger equipment), while lower reflux saves energy but can reduce purity. The other options describe different flows in the system and are not what the reflux ratio measures.

Reflux ratio measures how aggressively you recycle liquid back into the column relative to the amount you withdraw as product. After the condenser, some liquid becomes the distillate and some is sent back down as reflux. The reflux ratio is defined as the flow rate of that reflux divided by the distillate flow rate. So the description that matches this is the ratio of the liquid returned to the column to the distillate taken off. This ratio controls separation quality: higher reflux improves purity and allows more efficient separation (at the cost of more energy and larger equipment), while lower reflux saves energy but can reduce purity. The other options describe different flows in the system and are not what the reflux ratio measures.