What is the reflux ratio at total reflux ?

Related Mcqs:

1. In a distillation operation, what is the effect of the temperature of the reflux stream (given below) on the condenser and reboiler loads? Reflux conditions: (i) Reflux stream is completely liquid and is at its bubble point. (ii) Reflux stream is below its bubble point ?

   A. Condenser and reboiler loads are the same in both the cases
   B. Reboiler load is the same in both the cases but condenser load is higher in case (ii)
   C. Condenser load is the same in both the cases but reboiler load is higher in case (ii)
   D. Both condenser and reboiler loads are higher in case (ii) as compared to case (i)

2. Pick out the correct relationship. (Where, Ri = internal reflux ratio Ro = external reflux ratio.) ?

   A. (1 + Ro) = Ro/Ri
   B. (1 – Ro) = Ro/Ri
   C. (1 + Ri) = Ro/Ri
   D. (1 – Ri) = Ro/Ri

3. If Rm is the minimum reflux ratio, the optimum reflux ratio may be around _________________ Rm ?

   A. 1.2 to 1.5
   B. 2.5 to 3
   C. 3 to 4
   D. 5

4. In continuous distillation, the internal reflux ratio (Ri) and the external reflux ratio (Re) are related as_____________________?

   A. Ri = Re/(1 – Re)
   B. Ri = (1 – Re)/Re
   C. Ri = Re
   D. Ri = Re/(1 + Re)

5. The reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. The reflux ratio is____________________?

   A. 2
   B. 0.5
   C. 50
   D. 150

6. Minimum reflux ratio in a distillation column results in_____________________?

   A. Optimum number of trays
   B. Minimum reboiler size
   C. Maximum condenser size
   D. Minimum number of trays

7. The feed to fractionating column is changed from saturated vapour to saturated liquid. If the separation and reflux ratio remains unchanged, the number of ideal stages will______________________?

   A. Increase
   B. Decrease
   C. Remain same
   D. Depend on saturated boiling point; may increase or decrease

8. In a distillation column, with increase in the reflux ratio, the heat removed in the cooler ______________________?

   A. Increases
   B. Decreases
   C. Remains unaffected
   D. And the heat required in reboiler decreases

9. If xD = overhead product molal composition and RD = reflux ratio, then slope and intercept of the operating line for rectifying section are respectively ?

   A. [xD/(RD + 1)], [RD/(RD + 1)]
   B. [RD/(RD + 1)], [xD/(xD + 1)]
   C. [xD/(RD + 1)], [(RD + 1)/RD]
   D. None of these

10. At minimum reflux ratio for a given separation__________________?

    A. Number of plates is zero
    B. Number of plates is infinity
    C. Minimum number of the theoretical plates is required
    D. Separation is most efficient