This set of Distillation Design Question Bank focuses on “Constant Molar Overflow and Other Assumptions”.

1. The method of construction of an x-y diagram was explained by

a) Richardson and Coulson

b) Robinson and Gilliland

c) Murphree and Fenske

d) Cremer and Pullong

View Answer

Explanation: Pseudo properties were given by Robinson and Gilliland, while Murphree and Fenske gave equations to calculate trays and efficiency respectively.

2. Consider the following data, L’ = 363 and slope of section is 1.55. Estimate Vapor flow rate on either side

a) 234

b) 284

c) 303

d) 456

View Answer

Explanation: The slope is given by L’/V’=1.55, V’ = 363/1.55 = 234.

3. The point where equilibrium curve and component balance meets is called as

a) Murphree point.

b) Intersection point

c) Junction point

d) Pinch point

View Answer

Explanation: At infinite stages the where equilibrium curve and component balance meets is called as pinch point.

4. HETP is defined?

a) Height equivalent to theoretical plate

b) High efficiency tower plate

c) High energy temperature point

d) Homotomy Engineer Temperature Point

View Answer

Explanation: HETP is Height equivalent to theoretical plate, also defined as ratio of HTU (height of transfer units) and NTU.

5. The condition where reflux and stripping ratio approaches to infinity is called as

a) Minimum reflux

b) Total reflux

c) Optimum ratio

d) Feed ratio

View Answer

Explanation: Both balance lines approaches to coincide such a condition is called Total reflux, the slope of rectifying and stripping line matches each other.

6. Which of following is an important assumption of McCabe Thiele method?

a) Heat loss is maximum

b) Heat loss is negligible

c) Heat loss is infinite

d) Can’t be specified

View Answer

Explanation: The major assumption of McCabe Thiele method is Heat loss is negligible and also an overhead reboiler and condenser are used to recover heat loss.

7. In which case Constant Molar overflow is true?

a) Equimolar counter diffusion

b) Equimolar co-current diffusion

c) Distinct overflow

d) Not Sure of Diffusion

View Answer

Explanation: CMO is totally based on the assumption of equal-molar counter diffusion, mainly used in the calculation of trays in the McCabe Thiele method.

8) In McCabe Thiele method, equilibrium line is drawn between

a) x-y

b) y-x

c) x*- y

d) y*-x

View Answer

Explanation: The equilibrium is always drawn between x-y mole ratios, where x is mole of liquid feed and y is the mole of gas at equilibrium conditions.

9. The equilibrium line is plotted on the graph at

a) Middle of both sections

b) 900 from stripping section

c) 450 from axis meet up

d) At meetup of axis

View Answer

Explanation: Equilibrium line is always plotted between axes at 450, while the 90 0 perpendicular is used to find the feed point on x-y graph.

10. The tray by tray approach method was given by

a) Sorel

b) McCabe

c) Fenske

d) Murphree

View Answer

Explanation: The oldest method of calculation was given by Sorel in 1893, Murphree gave equations for efficiency, Fenske for the minimum trays.

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