Download SGBAU (Sant Gadge Baba Amravati university) B-Tech/BE (Bachelor of Technology) 7th Sem Chemical Engineering Chemical Engineering Operations III Previous Question Paper
11657 : Chemical Engineering Operations - III : Mass Transfer - II : 7 CHv01
P. Pages : 3 n ? AW - 3376
Time : Three Houi's lmllzmslj? Max. Marks : 80
Answer Three question from Section A and Three question from Section B.
Due credit will be given to neatness and adequ dimensions.
Assume suitable data wherever necessary.
Diagrams and chemical equations should be given wherever necessary.
Notes : 1
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5. Illustrate your answer necessary with the help of neat sketches.
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Discuss the reaction, mechanism wherever necessary.
. Cell phones are not permitted. 7
Use of pen Blue/Black ink/re?ll only for writing the answer book.
SECTION - A
1. a) Distinguish between distillation and liquid -liquid extraction in brief. 7
b) Explain how does the term relative volatility (on) of distillation is analogous to selectivity 6
( B) in liquid-liquid extraction operation? State it?s signi?cance in respective mass transfer
' operation.
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2. a) De?ne the terms distribution coef?cient and distn'bution constant in dilute solutions at 6
equilibrium.
b) Describe continuous multistage cross current extraction system for immiscible solvents with 7
the help of schematic diagram. How would you determine number of stages required using
graphical construction method?
3. a) A solution containing 5% acetaldehyde and 95% toluene is to be extracted with water 8
(solvent) in a ?ve (5) stage cross current extraction unit to extract acetaldehyde. Toluene
and water are immiscible. If 25 kg of water each time are used per 100 kg of feed calculate
the amount of acetaldehyde extracted and the ?nal concentration of the exit (raffmate)
solution. 7
The equilibrium relationship is given as Y = 2.20 X
Where _
Y= kg of acetaldehyde/ kg' of water
X = kg of acetaldehyde/ kg toluene.
b) Describe with the help of neat sketch the working of stage type extractor - mixer settler. 6
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1000 kilograms of an aqueous solution containing 35% mass trimethylamine (TMA) and 14
65% water is to be extracted using benzene as the solvent. A three stage cross current
extraction system is suggested. ?1" he amounts of (9 % benzene, 2% TMA) to be used in
successive stages are 815 kg. 950 kg and 2625 kg. Determine the fraction of solute removed
ifthe stages are ideal. The compositions of the ra?inate and extract phases as well as the tie
line data are given below -
Water - A
Benzene - B
Trimethylamine (TMA; - C
Equilibrium data:-
PRamnatematenricii xn 0004 000610.01 0.02 0.03 0.036 o.07?:o.13
ghasc 7 7/ xr L005 0.10 I 0.15 0.20 0.35 0.30 0.35 0.40 .
(Extract) Benzene rich _\'B ' 0.95 0.90 0.84 0.78 0.71 0.63 0.50 i 0.26
1213?c,._____.__ ?_ _? Vc 0.05 1 0.10 0.15 0.20 20-25 0.30 0.35 ? 0.40
Tie line data 'XC 0.04 0.083 0.13 0.215 0.395
\'C 0.035 0.068 0.09 0.145 0.31
a) How would you classify liquid - liquid extractors? Describe with the help of neat sketch 7
spray column extractor.
b) What is solid?liquid extraction? When would you prefer it? state any two industrial 6
examples of it.
OK
Describe a three stage crosscurrent leaching operation in which unequal amounts of the 13
leaching solvent 01?th same composition are used in all three stages with the help of
schematic diagram.
SECTION - B
a) Explain ?ash or Equilibrium distillation with the help of schematic diagram. Derive the 7
operating line equation or material balance equation of ?ash distillation and show it on
equilibrium (x-y) diagram.
b) A feed of 50 mole % hexane and 50 mole % octane is fed to a pipe still through pressure 7
reducing valve (P. R. V. ) and then into a ?ash separator. The Vapour and liquid leaving the
separator are assumed to be in equilibrium. If the fraction of the feed is converted into
vapour is 0.5. F ind the composition of the top and bottom products. The equilibrium data is
given below.
Molefmction ofhexane 17 0.69 0.4 0.192 0.045
Mole fraction ofoctane 1 0.932 0.78 0.538 0.1775 0
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OR
a) ax
What is relative volatility (a )? Derive the expression of y = W with the help of
+ a -? x
Rault's law and Dalton's law.
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b) 'A' mixture of 35 mole % A and 65 mole % 'B' is to be separated in distillation column. The
composition of component A in distillate is 93 mole % and 96 mole % of all 'A' is in
distillate. The feed is panially vapour and paitially liquid. The re?ux ratio is 4:1. Relative
volatility (0A3) = 2.5. How many number of ideal or theoretical stages are in each section
of the column?
What is? azeotrope and azeotropic distillation? Describe minimum boiling and maximum
boiling azeotropes with the help of temperature composition diagram and equilibrium
diagram.
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Discuss total re?ux ratio (Rm) minimum fe?ux ratio (Rm ) with the help of (x v/s y)
equilibrium diagram. Derive the equation used for calculation of minimum re?ux ratio
Rm (saturated liquid feed).
a What are different types of plates used for contacting vapour and liquid phases in plate
column? Explain sieve plated disperser with the help of neat diagram.
b) How would you calculate HETP 1n packed column for continuous distillation with the
help of empirical equation? .
OR
a) What is extractive'distillation method? When would you prefer it?
b) Discuss various factors determining column performance.
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This post was last modified on 10 February 2020