Engineering Questions with Answers - Multiple Choice Questions

# Distillation Design MCQ’s – Mccabe Thiele Diagram-Line Equation

1 - Question

The overall material balance of the tower is given by
a) L= V+W
b) F=D+W
c) D= F+HD
d) D= V+HD

Explanation: The overall material balance equation is given as F=D+W where F is the flow rate, D is the distillate and W is the withdrawn product.

2 - Question

If R=1.5 and xd= 0.96, then intercept of enriching line is estimated as
a) 0.384
b) 0.234
c) 0.5
d) 0.96

Explanation: As xD/R+1 = 0.96/1.5+1 =0.384.

3 - Question

The real number of trays are obtained as ratio of
a) Number of ideal trays and flow rate
b) Number of ideal trays and efficiency
c) Number of ideal trays and reflux ratio
d) Number of ideal trays and stripping ratio

Explanation: Number of ideal trays divided by the tray efficiency gives us the real number of trays, Number of ideal trays and reflux ratio gives us the ease of separation.

4 - Question

If the ideal trays are 7.7 and the efficiency of each one is 0.5, then real number of trays are
a) 15.4
b) 14.1
c) 15.0
d) 18.5

Explanation: The real number of trays are 7.7/0.5 = 15.4.

5 - Question

If the D -> 0, then the condition is called as
a) Total Boil up
b) No distillation
c) No Separation
d) Total Reflux

Explanation: When D tends to zero no product is withdrawn which is called as total reflux, and when D-> infinity this is called total boil up.

6 - Question

In the Fenske’s equation, xw and yw are
a) Equilibrium liquid and vapor concentration
b) Equilibrium distilled content
c) Partial vapor concentrations of liquid and solid
d) Total vapor and liquid rate

Explanation: Fenske’s equation makes use of equilibrium liquid and vapor concentration, Equilibrium distilled content is used by the McCabe Thiele method.

7 - Question

Sometime the reboiler is also considered as the
a) Reflux item
b) Extra equity
c) Heat extractor
d) Extra Stage

Explanation: The reboiler is sometimes used as an extra stage of operation of distillation, because the heat dissipated is also considered in the calculation of trays.

8 - Question

If feed is saturated vapor, then
a) q = 1
b) q= 0.5
c) q= 0
d) q= infinite

Explanation: When the feed is saturated vapor then lines passes through (zF,zF) i.e. q = 0, when q is infinite the feed is totally withdrawn

9 - Question

If the feed is saturated liquid, then
a) q = 1
b) q= 0.1
c) q = F
d) q= 0

Explanation: When the feed is saturated liquid with a vertical line which then lines passes through (zF,zF) i.e. q = 0.

10 - Question

At total reflux when operating line coincides diagonal line then?
a) xNm= y*
b) xNm= y
c) xNm= yw
d) xNm= xw