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

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. 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)

4. 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

5. What is the reflux ratio at total reflux ?

   A. Zero
   B. Infinity
   C. Unity
   D. Data insufficient

6. In case of binary distillation, increasing the reflux ratio above optimum does not result in the increase of_______________________?

   A. Area between operating line and 45° diagonal x-y diagram
   B. Condenser and reboiler surfaces
   C. Tower cross-section
   D. None of these

7. 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

8. The operating cost of a distillation column at minimum reflux ratio is____________________?

   A. Minimum
   B. Maximum
   C. Infinite
   D. Zero

9. 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

10. As the reflux ratio in a distillation column is increased from the minimum, the______________________?

    A. Slope of the operating line in stripping section decreases
    B. Number of plates decreases very slowly first and then more and more rapidly
    C. Total cost first decreases and then increases
    D. Liquid flow increases while the vapor flow decreases for a system