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Name
Reg No

APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY
07 THRISSUR CLUSTER
SECOND SEMESTER M.TECH. DEGREE EXAMINATION APRIL 2018
CHEMICAL ENGINEERING
PROCESS CONTROL
07CH6102 ADVANCED CHEMICAL REACTION ENGINEERING
Time:3 hours Max.Marks: 60
Answer all six questions. Part of each question is compulsory.
Answer either part or part of eachquestion
Q.no. Module 1 Marks
1a Liquid A decomposes by second order kinetics, and in a batch reactor 50% of
A is converted in a 5 minute run. How much longer would it take to reach 75%
conversion?
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Answer b or c
b Derive the performance equation for a steady-state back mixed flow reactor.
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c The homogeneous gas decomposition of R+6S proceeds at 6490C
with the first order rate CA. What size of plug flow reactor
operating at 6490C and 460kPa can produce 80% conversion of 40 mol of pure
A per hour?
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Q.no. Module 2 Marks
2a Explain general graphical design procedure for finding out the volume required
for a particulat reactor.
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Answer b or c
b Derive the expression for finding the conversion of adiabatic and nonadiabatic
operations in PFR/MFR.
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c The concentration readings in table given below represent a continuous
response to a pulse input into a closed vessel which is to be used as a
chemical reactor. Calculate the mean residence time of fluid in the vessel
and tabulate and plot the exit age distribution E.
Time
min
0 5 10 15 20 25 30 35
Cpulse
gm/l
fluid
0 3 5 5 4 2 1 0
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Q.no. Module 3 Marks
3a A gas containing A (2mol/m3) is fed m3/hr) to a plug flow reactor with recycle
loop (0.02 m3 loop volume, 3 kg of catalyst), and the output composition from
the reactor is 0.5 mol A/m3. Find the rate equation for the decomposition of A
for very large recycle, first order kinetics, inerts in feed.
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Answer b or c
b Derive the expression for effectiveness factor for a first order reaction on a
porous catalyst.
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c Derive performance equation for reactions containing porous catalyst for plug
flow reactor.
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Q.no. Module 4 Marks
4a Describe in detail different contacting patterns of fixed bed reactors for uniform
temperature distribution.
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Answer b or c
b Explain the K-L Model of bubbling fluidised bed by stating the assumptions
and salient equations.
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c
A single catalytic packed bed reactor is to be designed to treat 100mol/s of
reactant A and produce product R. Feed gas enters ar 2.49MPa 300K, the
maximum allowable temperature is 900K unless otherwise noted, and the inlet
temperature is 600K, the product stream is wanted at 300Kand thermodynamic
and kinetics of the exothermic reaction are given to us 40J/mol. for all
materials and at all temperatures, ΔHr= -80000 J/mol, same value at all
temperatures). Prepare a sketch showing the details of the system you plan to
use.
Type of reactor-plug,recycled or mixed
Amount of catalyst needed.
Heat duty ahead of the reactor, at the reactor itself and after the reactor.
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The temperature of all fluid streams.
Work out a good design for 80% conversion of feed consisting of 1molA and
7mol inert.
XA 0.8 0.78 0.7 0.6 0.5 0.1 0
-rA 0.05 0.1 0.2 0.225 0.2 0.05 0.03
Q.no. Module 5 Marks
5a Write the general rate expression for the reaction on catalyst surface

products
And also the rate expression if
i. The system with pure liquid B and slightly soluble gas A
ii. The system with dilute liquid B and highly soluble gas A
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Answer b or c
b Hydrogen gas is bubbled into an agitated tank m3r) containing liquid
butynediol (CB0=2500mol/m3 plus a dilute suspension of palladiumimpregnated
porous catalyst pellets m cat, ρ=1450 kg /m3 cat,
De=5*10-10 m3l/m cat.s, fs= 0.0055). Hydrogen dissolves in the liquid
(HA=148000 Pa.m3l/mol) and reacts with the butynediol on the catalyst surface
as follows:
+butynediol (l)butynediol and at 350C.
-rA=k'CACB and m6l/kg.molcat.s
Unused hydrogen is recompressed and recirculated, and the whole operation
takes place at 1.46 atm and 350C. Find out how it will take for 90% conversion
of reactant. The mass transfer rates are given as (KAiai)g+l=0.2777 m3l/m3r.s,
KAC=4.4*10-4 m3l/m3r.s
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c Dilute aqueous ethyl alcohol is oxidised to acetic acid by the action of pure
oxygen at 10 atm in a trickle bed reactor maintained at 300C and packed with
Pd-Al2O3catalyst pellets. The reaction proceeds as follows:
CH3COOH(l)+H2O
The reaction is first order with respect to Hydrogen and zero order with respect
to ethyl alcohol with rate constant at 300C=1.77*10-5 m3l/(kg cat.s)
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Calculate the fractional conversion of ethyl alcohol if gas and liquid are fed to
the top of a reactor.
Data:
Gas: νg=0.01 m3 HA=86000Pa.m3/mol
Liquid: m3 CB0=400 mol/m3
Reactor:5 m high, 0.1 m2 cross section, fs=0.58
Catalyst: dp=5mm,ρ=1800 kg/m3, De=4.16*10-10 m3/ mcat.s
Kinetics: kAgai=3*10-4 mol/m3 Pa.s, kAlai=0.02 s-1,kAC=3.86*10-4 m/s
Q.no. Module 6 Marks
6a Derive the rate equation for straight mass transfer for gas liquid reaction.
.
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Answer b or c
b Air with gaseous A bubbles through a tank containing aq. B. Raction occurs as
follows.
-rA kCA CB2 k=106m6/mol2.hr.
For this system,
kAga 0.01 mol/hr.m3.Pa, fl 0.98, kAla 20hr-1, HA 105 Pa. m3/mol. very low
solubility. DAl DBl 10-6 m2/hr. A 20 m2/m3
for a point in the absorber-reactor where, pA 0.0005Pa. and CB 100 mol/m3
1. locate the resistance to reaction what in gas film, in the liquid film,
in the main body of liquid)
2. locate the reaction zone.
3. Determine the behaviour in the liquid film (Whether pseudo first order
reaction, instantaneous, physical transport etc)
4. Calculate the rate of reaction
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c Illustrate the design procedure for straight mass transfer in countercurrent
towers.
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