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# Distillation Design MCQ’s – Analytical X-Y Diagram -Smoker’s Equation

Smoker proposed an analytical closed form formula, to calculate

a) Reflux ratio

b) Number of trays

c) Number of stages

d) Number of feeds

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Answer: b

Explanation: In 1938, Smoker proposed an analytical closed form formula to calculate the number of stages in a binary distillation column

. The analytical formula fails to predict the

a) Equilibrium Stages

b) Reflux ratio

c) Feed inlet and outlet

d) Boil up

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Answer: a

Explanation: The analytical formula fails to predict the Equilibrium Stages with reasonable accuracy, while reflux and boil up are predicted as ratio.

. In the below diagram, the minimum reflux can be seen as ______ using smoker’s equation.

a) 1.567

b) 1.425

c) 1.2

d) Can’t be specified

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Answer: b

Explanation: By tracking the locus to the x axis of smoker’s line reflux is seen to be intersecting at the abscissa of 1.425 on the x axis.

Smoker’s equation is convenient to use, in binary separations with

a) Large number of stages

b) Small number of stages

c) Independent stages

d) Dependent stages

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Answer: a

Explanation: Smoker’s equation is convenient to use in binary separations with large number of stages, while Fenske’s for the minimum number of trays

Smoker’s equation is based on assumption?

a) Constant molar overflow and volatility

b) Constant Molar overflow and viscosity

c) Constant feed and stages

d) Constant Pressure

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Answer: a

Explanation: Smoker’s equation is based on assumption of Constant molar overflow and volatility, while McCabe and Ponchan are based on Constant molar overflow only.

If N_{R} is 5.44 and N_{S} is 3.42. Total stages are

a) 2.02

b) 1.8

c) 8.86

d) 1.59

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Answer: c

Explanation: as N_{R} + N_{S} = 5.44 + 3.42 = 8.86.

According to smoker’s equation, b is given as

a) R+1

b) x_{D}/R+1

c) x_{D}/y

d) y/R+1

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Answer: b

Explanation: According to smoker’s equation b is given as x_{D}/R+1, where X_{D} is the moles of liquid distilled with the rate of reflux R.

According to smoker’s equation, C is given as

a) 1 + (α -1) k

b) 1 -(α -1)k

c) 1 -(α +1)k

d) α -1

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Answer: a

Explanation: According to smoker’s equation C is given as 1 + (α -1) k, where k value is calculated from bottom and top sections of the column.

Calculate b? If x_{D}= 0.95 and R=8

a) 0.445

b) 0.118

c) 0.2375

d) 0.568

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Answer: c

Explanation: AS x_{D}/R+1 = 0.95/8+1= 0.2375.

If reflux ratio is 3, then slope m is estimated as

a) 0.75

b) 1

c) 0.66

d) 0.90

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Answer: a

Explanation: As R/R+1 = 3/3+1 = 0.75.