At __________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation.

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 condensor and reboiler loads are higher in case (ii) as compared to case (i)

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 (α_AB = 2) does not change appreciably in the coloumn.

A

5

B

9

C

12

D

28

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

A

0

B

1

C

∞

As the reflux ratio in a distillation coloumn 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

In a continuous distillation column, the optimum reflux ratio ranges from __________ times the minimum reflux ratio.

A

1.1 to 1.5

B

1.6 to 2

C

2.2 to 2.6

D

2.7 to 3

In leaf springs, the maximum bending stress developed in the plates is (where W = Load acting on the spring, $$l$$ = Span of the spring, n = Number of plates, b = Width of plates and t = Thickness of plates)

A

$$\frac{{{\text{W}}l}}{{{\text{nb}}{{\text{t}}^2}}}$$

B

$$\frac{{3{\text{W}}l}}{{2{\text{nb}}{{\text{t}}^2}}}$$

C

$$\frac{{2{\text{W}}l}}{{{\text{nb}}{{\text{t}}^2}}}$$

D

$$\frac{{3{\text{W}}l}}{{{\text{nb}}{{\text{t}}^2}}}$$

In McCabe-Thiele method of theoretical plate calculation for a distillation column, the operating lines of stripping and rectifying sections coincide with the diagonal at __________ reflux.

A

Total

B

Minimum

C

Operating

D

Maximum permissible

Fenske-Underwood equation used for calculating the minimum number of theoretical plates in distillation column is valid for

A

Constant molal overflow

B

Total reflux

C

Constant relative volatility

D

All of the above

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 (R_i) and the external reflux ratio (R_e) are related as

A

$${{\text{R}}_{\text{i}}} = \frac{{{{\text{R}}_{\text{e}}}}}{{1 - {{\text{R}}_{\text{e}}}}}$$

B

$${{\text{R}}_{\text{i}}} = \frac{{1 - {{\text{R}}_{\text{e}}}}}{{{{\text{R}}_{\text{e}}}}}$$

C

$${{\text{R}}_{\text{i}}} = {{\text{R}}_{\text{e}}}$$

D

$${{\text{R}}_{\text{i}}} = \frac{{{{\text{R}}_{\text{e}}}}}{{1 + {{\text{R}}_{\text{e}}}}}$$

At __________ reflux, theoretical number of plates in a distillation coloumn is calculated using Fenske-Underwood equation.

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