A distillation column with N plates is being operated under normal conditions. At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped). At the new steady state ?

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. A distillation column separates 10000 kg/hr of a benzene-toluene mixture as shown in the figure below: In the figure xF, xD and xW represent the weight fraction of benzene in the feed, distillate and residue respectively. The reflux ratio is_______________ ?

   A. 0.5
   B. 0.6
   C. 1.0
   D. 2.0

3. For the same feed, feed quality and separation (in a distillation column), with the increase of total pressure, the number of ideal plates will_____________________?

   A. Increase
   B. Decrease
   C. Remain same
   D. Data insufficient, can’t be predicted

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. At what value of reflux ratio, number of theoretical plates in a distillation column is minimum ?

   A. 0
   B. 1
   C. ∞
   D. < 1

6. On moving the feed line (q-line) from saturated liquid feed (vertical position) to saturated vapor feed (horizontal feed), if the slope of both the operating lines are to be increased, then it will result in______________________?

   A. Greater degree of separation with a fixed number of trays
   B. Increased reboiler load
   C. Increased reflux ratio
   D. None of these

7. According to the Fenske equation, what will be the minimum number of plates required in a distillation column to separate an equimolar binary mixture of components A and B into an overhead fraction containing 99 mol% A and a bottom fraction containing 98 mol% B ? Assume that relative volatility (αAB = 2) does not change appreciably in the column ?

   A. 5
   B. 9
   C. 12
   D. 28

8. When the feed to a distillation column is a saturated liquid, slope of the feed line is_____________________?

   A. Zero
   B. Unity
   C. Infinity
   D. None of these

9. 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)

10. For a fixed number of ideal stages in a distillation column, as the reflux ratio is increased, the difference in composition between the top and bottom product streams__________________?

    A. Increases
    B. Decreases
    C. Remain unaffected
    D. Passes through a maximum