This set of Distillation Design Multiple Choice Questions & Answers (MCQs) focuses on “Mccabe Thiele Diagram-Construction”.

1. The component balance of the component A is given as

a) Fz_{F}= Dx_{D} + Wx_{w}

b) Fz_{F}= Dx_{D} – Wx_{w}

c) Fz_{F}= Dx_{D}/Wx_{w}

d) Fz_{F}= Dx_{D} *Wx_{w}

View Answer

Explanation: According to McCabe Thiele method material balance over is given as Fz

_{F}= Dx

_{D}+ Wx

_{w}, where F is the total feed.

2. If F= 200 kmol/h and Z_{F}=0.4, X_{D}=0.95, X_{W}=0.04 and R=2.0, Then D is

a) 88.1

b) 22.6

c) 79.1

d) 158.2

View Answer

Explanation: Using equation Fz

_{F}= Dx

_{D}+ Wx

_{w}substituting values we get D=79.1.

3. The very First step of McCabe method is?

a) Plot the equilibrium curve

b) Plot diagonal curve

c) Plot Operating line

d) Plot stripping line

View Answer

Explanation: Firstly we plot the Equilibrium diagram from the given equilibrium data, then the diagonal curve and then plot the operating line.

4. Calculate Boil up? If vapor flow and bottom withdrawal are 237.3 and 120.9 respectively

a) 1.5

b) 2.9

c) 2.111

d) 1.963

View Answer

Explanation: As boil up is ratio of vapor flow and bottom withdrawal then 237.3/120.9 = 1.963.

5. If ZF¬=0.58 and also feed contains 35% mole of the liquid, then intercept of y axis is

a) 0.892

b) 0.205

c) 0.707

d) Can’t be calculated

View Answer

Explanation: As – (Z

_{F}/q-1) using values -0.58/ (0.35-1) = 0.892.

6. If Z_{F}=0.6 and also feed contains 72% mole of the liquid, then intercept of x axis is

a) 0.744

b) 0.899

c) 0.833

d) 1.2

View Answer

Explanation: As (ZF/q) using values 0.6/ (0.72) = 0.833.

7. Calculate minimum reflux? If intercept is 0.56 and X_{D}= 0.96

a) 0.174

b) 0.125

c) 0.21

d) 0.28

View Answer

Explanation: As 0.56=X

_{D}/ (R

_{M}+1) = 0.96/ (R

_{M}+1) M= 0.174.

8. Slope of rectifying line is given by

a) R/X_{D}

b) R/(R+1)

c) F/ (D+W)

d) R/(R+1)

View Answer

Explanation: The rectifying line slope is always given as ratio of Reflux ratio plus unity i.e. R/(R+1), While R/X

_{D}gives us the reflux to liquid ratio for the operation.

9. If x_{D}=0.95, x_{W}= 0.04 and α=2.5. Find total trays?

a) 7

b) 6.7

c) 7.7

d) 6

View Answer

Explanation: Using Fenske’s equation total number of trays to be calculate are 5.7 as N

_{m}+ 1 then 5.7+1 = 6.7 which is the final answer.

10. A Pinch point may occur at intersection of feed line and

a) Stream line

b) Stripping line

c) Rectifying line

d) Equilibrium line

View Answer

Explanation: Pinch point always occurs at intersection of feed line and equilibrium line, while plot of x and y are called as the Equilibrium line.

**Sanfoundry Global Education & Learning Series – Distillation Design. **

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