Download GTU (Gujarat Technological University) BE/BTech (Bachelor of Engineering / Bachelor of Technology) 2019 Winter 7th Sem New 2170501 Chemical Reaction Engineering Ii Previous Question Paper
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VII (New) EXAMINATION ? WINTER 2019
Subject Code: 2170501 Date: 23/11/2019
Subject Name: Chemical Reaction Engineering - II
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Extra graph may be provided.
Q.1 (a)
From the first principle, prove that for a back mix reactor E
?
= e
-?
03
(b) Explain complete segregation and complete micro-mixing.
04
(c) A sample of the tracer hytane at 320 K was injected as a pulse to a reactor,
and the effluent concentration was measured as a function of time. The
measurements represent the exact concentrations at the times listed and not
average values between the various sampling tests.
i. Construct E(t) curve.
ii. Determine the fraction of material leaving the reactor that has spent
8 min or more in the reactor.
t, min 0 1 2 3 4 5 6 7 8 9 10 12 14
Cpulse, gm/l 0 1 5 8 10 8 6 4 3 2.2 1.5 0.6 0
07
Q.2 (a) Comment on the three moments of RTD. 03
(b) Discuss Segregation model in brief. 04
(c) A sample of the tracer hytane at 320 K was injected as a pulse to a reactor,
and the effluent concentration was measured as a function of time resulting
in the data shown in table below
t, min 0 5 10 15 20 25 30 35 40 45 50
Cpulse, gm/l 0 1.2 3.1 4.2 5.8 3.5 2.2 1.6 1.0 0.4 0
The measurements represent the exact concentrations at the times listed and
not average values between the various sampling tests. Calculate Peclet
number, if dispersed plug flow model exists.
07
OR
(c) Air with gaseous A bubbles through a tank containing aqueous B. Reaction
occurs as follows
A(g)+2B(l) ?R(l)
-rA = kCACB
2
k = 10
6
m
6
/mol
2
.hr
For this system
k Ag a = 0.01 mol/hr.m
3
.Pa fl = 0.98
kAl a = 20 hr
-1
HA = 10
4
Pa.m
3
/mol
DAl = DBl = 10
-6
m
2
/hr a = 20 m
2
/m
3
reactor
For a point in the absorber-reactor where PA = 5000 Pa and CB = 100
mol/m
3
1) Locate the resistance to reaction
2) Calculate the rate of reaction (mol/m
3
hr)
07
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1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VII (New) EXAMINATION ? WINTER 2019
Subject Code: 2170501 Date: 23/11/2019
Subject Name: Chemical Reaction Engineering - II
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Extra graph may be provided.
Q.1 (a)
From the first principle, prove that for a back mix reactor E
?
= e
-?
03
(b) Explain complete segregation and complete micro-mixing.
04
(c) A sample of the tracer hytane at 320 K was injected as a pulse to a reactor,
and the effluent concentration was measured as a function of time. The
measurements represent the exact concentrations at the times listed and not
average values between the various sampling tests.
i. Construct E(t) curve.
ii. Determine the fraction of material leaving the reactor that has spent
8 min or more in the reactor.
t, min 0 1 2 3 4 5 6 7 8 9 10 12 14
Cpulse, gm/l 0 1 5 8 10 8 6 4 3 2.2 1.5 0.6 0
07
Q.2 (a) Comment on the three moments of RTD. 03
(b) Discuss Segregation model in brief. 04
(c) A sample of the tracer hytane at 320 K was injected as a pulse to a reactor,
and the effluent concentration was measured as a function of time resulting
in the data shown in table below
t, min 0 5 10 15 20 25 30 35 40 45 50
Cpulse, gm/l 0 1.2 3.1 4.2 5.8 3.5 2.2 1.6 1.0 0.4 0
The measurements represent the exact concentrations at the times listed and
not average values between the various sampling tests. Calculate Peclet
number, if dispersed plug flow model exists.
07
OR
(c) Air with gaseous A bubbles through a tank containing aqueous B. Reaction
occurs as follows
A(g)+2B(l) ?R(l)
-rA = kCACB
2
k = 10
6
m
6
/mol
2
.hr
For this system
k Ag a = 0.01 mol/hr.m
3
.Pa fl = 0.98
kAl a = 20 hr
-1
HA = 10
4
Pa.m
3
/mol
DAl = DBl = 10
-6
m
2
/hr a = 20 m
2
/m
3
reactor
For a point in the absorber-reactor where PA = 5000 Pa and CB = 100
mol/m
3
1) Locate the resistance to reaction
2) Calculate the rate of reaction (mol/m
3
hr)
07
2
Q.3 (a) Write in brief on how solubility data cam help to predict the kinetic regime
for fluid -fluid reactions
03
(b) How can Hatta number be used to decide the type of contacting device for
fluid ?fluid reactions
04
(c) Uniform-sized spherical particles UO3, are reduced to UO2, in a uniform
environment with the following results:
t, h 0.180 0.347 0.453 0.567 0.733
XB 0.45 0.68 0.80 0.95 0.98
If reaction follows the Shrinking Core Model, find the controlling
mechanism and rate equation to represent this reduction.
07
OR
Q.3 (a) A closed vessel has flow for which dispersion number is 0.01, we wish to
represent this vessel by tanks in series model. What value of number of tanks
should be selected?
03
(b)
Gaseous reactant A diffuses through a gas film and reacts on the surface of
a solid B according to a reversible first order reaction: -r = k
s
(Cs ? Ce),
where Ce is the equilibrium concentration of A. Develop an expression for
the rate of reaction accounting for both the mass transfer and reaction steps.
04
(c) Ram and Rima performed roasting of spherical solid particles containing B
isothermally in an oven with gas of constant composition. Solids were
converted to form non-flaking product according to the SCM as follows:
A(g)+B(s) ?R(g)+S(s)
CA=0.01 kmol/m
3
The density of solid B is 20 kmol/m
3
. From the following
conversion data (by chemical analysis) or core size data (by slicing and
measuring), Ram proposed ash layer controlling while Rima proposed gas layer
as the rate controlling mechanism for the transformation of solid from the
kinetic data show below,
dp (mm) XB t, sec
1 0.3 2
1 0.75 5
Justify who is correct?
07
Q.4 (a) Draw a plot to show the progress of reaction of a single spherical particle of
constant size with surrounding fluid measured in terms of time for complete
conversion for all the different resistances.
03
(b) Derive the rate equation for fluid?fluid reaction in the case of instantaneous
irreversible reaction with higher concentration of constituent B.
04
(c) A solid feed consisting of 30% of 1 mm particles and smaller, 30% of 2 mm
particles and rest 4 mm particles all on weight basis, is to be passed through
a tubular reactor like rotary kiln, where it reacts with gas of constant
composition to give a hard solid product. Experiments show that the
progress of conversion can reasonably be represented by reaction control in
unreacted core model and that the time for complete conversion of 4 mm
particle is 4 hours. Find the residence time needed in the tubular reactor for
85 % conversion of solids.
07
OR
FirstRanker.com - FirstRanker's Choice
1
Seat No.: ________ Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER ? VII (New) EXAMINATION ? WINTER 2019
Subject Code: 2170501 Date: 23/11/2019
Subject Name: Chemical Reaction Engineering - II
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
4. Extra graph may be provided.
Q.1 (a)
From the first principle, prove that for a back mix reactor E
?
= e
-?
03
(b) Explain complete segregation and complete micro-mixing.
04
(c) A sample of the tracer hytane at 320 K was injected as a pulse to a reactor,
and the effluent concentration was measured as a function of time. The
measurements represent the exact concentrations at the times listed and not
average values between the various sampling tests.
i. Construct E(t) curve.
ii. Determine the fraction of material leaving the reactor that has spent
8 min or more in the reactor.
t, min 0 1 2 3 4 5 6 7 8 9 10 12 14
Cpulse, gm/l 0 1 5 8 10 8 6 4 3 2.2 1.5 0.6 0
07
Q.2 (a) Comment on the three moments of RTD. 03
(b) Discuss Segregation model in brief. 04
(c) A sample of the tracer hytane at 320 K was injected as a pulse to a reactor,
and the effluent concentration was measured as a function of time resulting
in the data shown in table below
t, min 0 5 10 15 20 25 30 35 40 45 50
Cpulse, gm/l 0 1.2 3.1 4.2 5.8 3.5 2.2 1.6 1.0 0.4 0
The measurements represent the exact concentrations at the times listed and
not average values between the various sampling tests. Calculate Peclet
number, if dispersed plug flow model exists.
07
OR
(c) Air with gaseous A bubbles through a tank containing aqueous B. Reaction
occurs as follows
A(g)+2B(l) ?R(l)
-rA = kCACB
2
k = 10
6
m
6
/mol
2
.hr
For this system
k Ag a = 0.01 mol/hr.m
3
.Pa fl = 0.98
kAl a = 20 hr
-1
HA = 10
4
Pa.m
3
/mol
DAl = DBl = 10
-6
m
2
/hr a = 20 m
2
/m
3
reactor
For a point in the absorber-reactor where PA = 5000 Pa and CB = 100
mol/m
3
1) Locate the resistance to reaction
2) Calculate the rate of reaction (mol/m
3
hr)
07
2
Q.3 (a) Write in brief on how solubility data cam help to predict the kinetic regime
for fluid -fluid reactions
03
(b) How can Hatta number be used to decide the type of contacting device for
fluid ?fluid reactions
04
(c) Uniform-sized spherical particles UO3, are reduced to UO2, in a uniform
environment with the following results:
t, h 0.180 0.347 0.453 0.567 0.733
XB 0.45 0.68 0.80 0.95 0.98
If reaction follows the Shrinking Core Model, find the controlling
mechanism and rate equation to represent this reduction.
07
OR
Q.3 (a) A closed vessel has flow for which dispersion number is 0.01, we wish to
represent this vessel by tanks in series model. What value of number of tanks
should be selected?
03
(b)
Gaseous reactant A diffuses through a gas film and reacts on the surface of
a solid B according to a reversible first order reaction: -r = k
s
(Cs ? Ce),
where Ce is the equilibrium concentration of A. Develop an expression for
the rate of reaction accounting for both the mass transfer and reaction steps.
04
(c) Ram and Rima performed roasting of spherical solid particles containing B
isothermally in an oven with gas of constant composition. Solids were
converted to form non-flaking product according to the SCM as follows:
A(g)+B(s) ?R(g)+S(s)
CA=0.01 kmol/m
3
The density of solid B is 20 kmol/m
3
. From the following
conversion data (by chemical analysis) or core size data (by slicing and
measuring), Ram proposed ash layer controlling while Rima proposed gas layer
as the rate controlling mechanism for the transformation of solid from the
kinetic data show below,
dp (mm) XB t, sec
1 0.3 2
1 0.75 5
Justify who is correct?
07
Q.4 (a) Draw a plot to show the progress of reaction of a single spherical particle of
constant size with surrounding fluid measured in terms of time for complete
conversion for all the different resistances.
03
(b) Derive the rate equation for fluid?fluid reaction in the case of instantaneous
irreversible reaction with higher concentration of constituent B.
04
(c) A solid feed consisting of 30% of 1 mm particles and smaller, 30% of 2 mm
particles and rest 4 mm particles all on weight basis, is to be passed through
a tubular reactor like rotary kiln, where it reacts with gas of constant
composition to give a hard solid product. Experiments show that the
progress of conversion can reasonably be represented by reaction control in
unreacted core model and that the time for complete conversion of 4 mm
particle is 4 hours. Find the residence time needed in the tubular reactor for
85 % conversion of solids.
07
OR
3
Q.4 (a) Draw neat diagram showing various contacting patterns for two phase
reacting system.
03
(b) List the steps visualized by Shrinking core model for spherical particles of
unchanging size.
04
(c) Explain Langmuir Hinshelwood Hougen Watson model for solid catalyzed
gas phase reaction.
07
Q.5 (a) What are the assumption for Langmuir Hinshelwood Hougen Watson model 03
(b) Write a brief note on Langmuir isotherm. 04
(c) Derive the effectiveness factor for first order catalyzed reaction 07
OR
Q.5 (a) Classify catalyst used in chemical industries 03
(b) Write a brief note on working of fluidized bed reactor 04
(c) Spherical particles of zinc blende of size R=2 mm are roasted in an 8%
oxygen stream at 800?C and 1 atm. The stoichiometry of the reaction is
2ZnS + 3O
2
? 2ZnO + 2SO
2
Assuming that reaction proceeds by the shrinking core model calculate the
time needed for complete conversion of a particle and the relative resistance
of ash layer diffusion during this operation. Film resistance can safely be
neglected as long as a growing ash layer is present.
Data:
Density of solid ?B = 4.13 gm/cm
3
Reaction rate constant k
s
? = 2 cm/sec
For gases in the ZnO layer ?
e
= 0.08 cm
2
/sec
07
*************
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This post was last modified on 20 February 2020