This set of Distillation Design Problems focuses on “Mccabe Thiele Diagram-Line Equation”.
1. 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
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The overall material balance equation is given as F=D+W where F is the flow rate, D is the distillate and W is the withdrawn product.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. 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
Explanation: As xD/R+1 = 0.96/1.5+1 =0.384.
3. 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
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. 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
Explanation: The real number of trays are 7.7/0.5 = 15.4.
5. 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
Explanation: When D tends to zero no product is withdrawn which is called as total reflux, and when D-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. 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
Explanation: Fenske’s equation makes use of equilibrium liquid and vapor concentration, Equilibrium distilled content is used by the McCabe Thiele method.
7. Sometime the reboiler is also considered as the
a) Reflux item
b) Extra equity
c) Heat extractor
d) Extra Stage
View Answer
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. If feed is saturated vapor, then
a) q = 1
b) q= 0.5
c) q= 0
d) q= infinite
View Answer
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When the feed is saturated vapor then lines passes through (zF,zF) i.e. q = 0, when q is infinite the feed is totally withdrawn.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. If the feed is saturated liquid, then
a) q = 1
b) q= 0.1
c) q = F
d) q= 0
View Answer
Explanation: When the feed is saturated liquid with a vertical line which then lines passes through (zF,zF) i.e. q = 0.
10. At total reflux when operating line coincides diagonal line then?
a) xNm= y*
b) xNm= y
c) xNm= yw
d) xNm= xw
View Answer
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.
Sanfoundry Global Education & Learning Series – Distillation Design.
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