A. Increases
B. Decreases
C. Remains unaffected
D. And the heat required in reboiler decreases
Related Mcqs:
- 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) - 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 - 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) - An aqueous solution of methanol is to be distilled in a tray column. High pressure steam is available as a source of heat. For a given reflux ratio and overhead composition, two options are being explored; (i) a reboiler is used and (ii) no reboiler is used but steam is fed directly to the bottom of the column. As compared to option (i), in option (ii) ____________________?
A. Less number of trays are required
B. Composition of the residue remains unchanged
C. More number of trays are required but the residue composition remains unchanged
D. More number of trays are required and the residue composition is more dilute in methanol - 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 At some point of time, the operation is shifted to total reflux condition (i.e., no product and residue are being withdrawn and feed to the column is stopped).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 ?
A. Composition of vapors and that of liquid do not vary throughout the column
B. Reboiler load and condenser load are minimum
C. The top and bottom compositions are unchanged with and without total reflux
D. The top and bottom compositions correspond to the maximum enrichment available - 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 - 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 - The operating cost of a distillation column at minimum reflux ratio is____________________?
A. Minimum
B. Maximum
C. Infinite
D. Zero - At what value of reflux ratio, number of theoretical plates in a distillation column is minimum ?
A. 0
B. 1
C. ∞
D. < 1 - 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
