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
View Answer
Answer: b
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The overall material balance equation is given as F=D+W where F is the flow rate, D is the distillate and W is the withdrawn product.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
View Answer
Answer: a
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
View Answer
Answer: b
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
View Answer
Answer: a
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
View Answer
Answer: d
Explanation: When D tends to zero no product is withdrawn which is called as total reflux, and when D-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
View Answer
Answer: a
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
View Answer
Answer: d
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
View Answer
Answer: c
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When the feed is saturated vapor then lines passes through (zF,zF) i.e. q = 0, when q is infinite the feed is totally withdrawn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
View Answer
Answer: a
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
View Answer
Answer: a
Explanation: The physical significance is given by Fenske’s equation that xNm= yw , where xNm is the liquid at the nth stage and yw is the gas withdrawal.