BIT Sindri, Dhanbad

Department of Chemical Engineering

Mid Semester Examination -|
B. Tech sh Semester (2023-24)
CHEMICAL REACTION ENGINEERING
Time : 90 Minutes
Total Marks: 20

Notes: (i) Attempt any five questions. Al questions carry equal marks.
(i) 1ssume suitable data, if required.
03. A gaseous feed of pure A (l molMiter) enters in a tubular reactor (2 liters) and reacts as
Tollows:
mol
2A ’ R, -r= 0.05CA Hter sec
Find what feed rate (liter/min) will give an outlet concentration CA=0.36 mol/liter [CO2]
. An aqueous reactant stream (5 mol A/Miter) passes througha mixed flow reactor followed by
a plug flow reactor. Find the concentration at the exit of the plug flow reactor if in the mixed
flow reactor CA =4 mol/liter. The reaction is second-order with respect to A, and the volume of
the plug flow unit is double of the mixed flow unit. [CO2]
(.A liquid phase homogeneous clementary reaction 2A ’B with 40% conversion of Atakes
place-in-a-plug-low-rcactor..lfwe_replace plug flow seactor by aback mixed reactor gf2.5.times
volume of that plug flow reactor., then find the conversion of A. [CO1.C02]
when
1 . Atpresent conversion of 86 %for elementary liquid reaction A ’ 2R
operating in an isothermal plug. flow reactor with a recycle ratio of 1. What will be the
conversion if the recycle ratio is increased to 2. [CO1,C02]
.An aqueous reactant Adecon:poses at 80 °C as follows:
A ’ 3P, -r = (0.8 min-1) CA . activation energy E= |1691.5 J/mol
Find the time required to achieve 98 % conversion of Aat 120 °C in an ideal batch reactor.
(CO1,c03]
versus XA gIaph decreases to a minimum from X = 0 to XA 0.60 and then
A6), (a) If
increases, suggest a multiple reactor system with minimum volumc for adesired conversion
[CO2]
of XA = 0.70. cSTRMFR
acts like a mixed flow
(b) Describes the yperating conditions in which a recycle rector
reactor and when it can be assumed as a plug low reactor? (C02)
parallel reactions.
). (a) Explain the term "Selectivity" and "Yield" with suitable examples of [CO1)
examples. In which condition
(b) Describe space time and holding time with suitable
space time and holding time are cqual.(FD SteodyNatt miaed eaclo)co1)
 S02
CHEMICAL ENGG.
Jharkhand University of Technology, Ranchi
B.Tech. 5th Semester Examination, 2022
Subject: Chemical Reaction Engineering Subject Code : CHC-s02
Time Allowed : 3 Hours Full Marks : 70

Candidates are required to give their answer in their own words as far as practicable.
Answer any five questions and Question No. I is compulsory.
All questions carry equal marks.
Assume suitable data andlor assumptions if required.
2x7-14
1. Choose the best possible answer for following multiple choice questions:
is half completed in 23 minutes will be:
(a) Reaction rate constant ofa first order reaction, which
) 0.03 min (ii) 003 hr
(iv) 0.03 sec
(ii) 0.0s min
the
(b) Limiting reactant in a chemical reaction decides
(i) reaction speed
(ü) cquilibrium constant
iv) conversion
(iii) rate constant
reactant.
reaction is the initial concentration of the
(c) Half-life period for a first order inverscly proportional to
) independent of (ü)
(iv) None of these
(iüi) dircctly proportional to rate of reaction
an exothermic reversible reaction is conducted adiabatically. the
(d) When minimum
(i) continuously increases (ü) passes through a
Niv) continuously decreases
Aii) passes through a maximum same volumne.
reaction is being carried out in a CSTR and PFR of
order
(e) An irreversible first The relative conversion
will
The liquid Molar flow rates are sane.
ii) be same in both cases
temperature. in PFR
(i) depend on the (iv) be more in CSTR than
PFR than in CSTR. flow reactor. Tbe
Hi) be more in
caried out in an adiabatic plug
second order reaction is
() An endothermic
is throughout the reactor.
rate of heat generation reactor. (ü) constant
the inlet of the of the reactor.
) maximum at reactor. (iv) maximum at the center
of the
(ii) maximum the exit the
is used to know
of fluid leaving a vessel
(g) The exit age
distribution
(ii) activation encrgies of a reaction.
non-ideal flow in the vessel.
i) extent of (iv) None of these
(ii) reaction mechanism. Please Turn Over

25466 60

riease Turn Over

 (2)

at 400 K the rate is reported as:

. (a) For a gas reaction
atm
dpA488p²A, hours rate e
for this reaction if the
units of the rate constant
What are the value and
expressed as
dN mol
-TA = dt = KC¤ mPs
themally cracks (breaks dowm
law. A 1300-K n-nonane
(b) Define the Arhenius rapidly as at 1000 K. Find
the activation energy for
smaller molecules) 22 times as 2
decomposition.
problem: A 20-minutes experimental
reactor and solve the
. (a) Define ideal batch second-order rate. What wo
is converted to product by
shows that 65% of liquid reactant 2+5
a half-hour run?
be the fraction converted in
in a batch reactor
P(A’P) and in the first 2 minutes
(b) Aqueous A reacts to form mol/iter to CAr= 3:50 mol/liter. Find the rate
equatic
concentration drops from C o 4-0
order with respect to A.
for the reaction if the kinetics is second
MFR. A gaseous feed of pun
of ideal
(a) Derive the performance equation follows:
reactor (2 liters) and reacts as
A(lmol/liter) enters a mixed flow
mol
2A ’ R, -rA =006CÃ iter.s 3+4-7
CA=04 molliter.
give an outlet concentration
Find what feed rate (liter/min) will liter,
gascous feed of pure A (2 mol
ideal plue flow reactor? A
(b) What do you mean by plug flow reactor. The kinetics of
give a variety of products in a
100 molmin) decomposes to
the conversion is represented by
A’ 25R, -r = (16min-) CA 2+5=7
Find the expected conversion in a 32 liter reactor. flow reactor followed
by a
passes through a plug if
(a) An aqueous reactant stream (4 mol A/liter) mixed flow reactor
the exit of the and
mixed flow reactor. Find the concentration at with respect to A,
Thereaction is second-order
in the plug flow rcactor CA =1 moliter. mixed| flow unit.
the volume of the plug flow unit is three times that of the coaversion is
10 molliter)
(b) For an irreversible first-order liquid-phase reaction (CAO recycled to the
1in a plug flow reactor. If two-thirds of the stream leaving
the reactor is
90% kept unchanged,
entrance, and if the throughput to the whole reactor recycle system is
reactoror
what does this do to the concentration of reactant
leaving the system
 S02
(3)
a
conversion for the clementary aqueous reaction in
equilibrium
Determine the between 10°C and 100°C.
reactor
isothermal plug flow
-15300AH298 =-78300CpA =CpR Constant.
R.AG98 temperature versus conversion.
form of the plot of
Dresent the results in the flow reactor? Explain with examples.
reactions in a Plug
multiple
What do you mean by 7+47=1

on any two of the following:

iteshort notes
flow reactor
RTD in non-ideal
curve
D E and F
model homogeneousreactions
(c) Tank in series find kinetics of
Differential method to
)
 And Jimf

BIT Sindri, Dhanbad

Department of Chemical Engineering
Mid Semester Examination -I1

B. Tech 5 Semester
CHEMICAL REACTION ENGINEERING

Time :90 Minutes Total Marks: 20 a

Notes: ) Attempt any five questions. All questions carry equal marks.
() Assume suitable data, if required.
out in an isothermal
An elementary homogeneous gas phase reaction A’2B is carried 50 minutes the find out the
batch reactor. If 50 % conversion of pure reactant A, is achieved in [CO2)
time required for 75 % conversion of A.
in a batch reactor
2) Consider the following consecutive unimolecular-type first-onder reactions requíred to
time
and derive the experession for maximum concentration ofR (CR)J and
reactant A was
achieve CR.max (tma) in terms of reaction rate constants. Initially there was only
present. K K
’R [CO1, CO2]
((3) Ahomogeneous liquid phase second order reaction 2Aby’B with 60% conversion of A
mixed reactor of double
takes place in a tubular reactor. If we replace tubular reactor a back [C02]
volume of that tubular reactor, then find the conversion of A.
unimolecuiar-type irSst-order
(4 A PFR anda CSTR are connected in series to carry out a for PFR is 5
isothermál liquid phase reaction. The rate constant is 0.10 sec. The space time [CO21
conversion of reactant.
seconds and space time for MFR is 12 seconds. Find the overall
conversion of 70 % for elementary homogeneous liquid phase ceaction 2A ’P
C t i i n a n isothermal recvele reactor with a recycle ratio of two. What will be the
When
conversion if the recyclc ratio is changed to one? [CO2]
i6:(a)'TFveraus Xi graph decreases to a minimum from X =0 to XA = 0.45 and then
volume for a desireá conversion
-rA
increases, suggest a multiple reactor system with minimurn
of XA =0.75. eyoe Fes choCo2)
all sutocatalytic cections. [CO1]
Yb) Suggest the most suitable reactor setu for
examples of parallel reactions.
(7), (a) Explain the term "Selectivity" and "Yieli" with prbper (CO1]
suitable examples. [COI]
(b) Describe space time and space velocity with

kIaye-kt

k Aoe
XA ISo Min.
 BIT Sindri, Dhanbad
Departaent of Chemical Engineering
Mid Senester Examination -|
B. Iech s Semester (2023-24)
CHEMICAL REACTION ENGINEERING
Total Marks: 20
Time: 90 MMinutes

Votes. (i) Attempi any five questioms. 4ll

questions urry equal murks.
(u)ssume suituhle data, if required
(2 liters) and reacts as
Agascous feed of pure A Imol liter) enters in a fubular reactor
follow s:
-,=0.05C m
2A R. liter sec

concentration CA 0.36 mol/liter (co2)

F1nd what feed rate (liter min) ill give an outlet
reactor followed by
Aliter) passes through a mixcd tlow
An aqucous rcactant strcam (5 inol mixed
at the exit of the plug low reactor if in the
a plug flow reactor. Find the con ntration
second-order with respect to A, and the volume of
low reactor CA- 4 mol liier. The teaction is (CO2]
the plug flow unit is douhBe of the mixed flow unit.
rcaction 2A B with 40 conversion of A takes
H. A lquid phasc homugencous clementary
tlow reactor by a back miNcd reactor gf.2.5 tumes
plave in a piuy lluw Icctor. lf we replace plug conversion of A |CO1.CO2]
olume of that plug flo reactor. hen find the
liquid reaction A- 2R when
(4). At present conversion of No 'e for clementary
of I. What will be the
operating in an Isothermal plus tlow rcactor wih d rccycle ratio |COLCO2]
conversIon if the recvcle ratio is uIcreascd to 2.
at 80 as follows:
. An aqueous rcactant A decon .poses
(0.8 min)Ca . 4ctis ation energy l691.5 J mol
A 3P.

Find the t1me reuquired to ahiee 98 conversion oe A at 120 C n an ideal batch reavtor
(COLCO

nmun Iro N 0.60 ad then

(6). (a) I! ersus X gah decreases to 4
nun solume or a lested comeson
inCreases. suggest a multuple reatut svsten s th
uf X 0 70
tlow
m whh a Cwe I r ats like a Ied
(b) DescTibes the operatmy conditos
reactor and when it can be assumed a plug low cAlor
th utable e\anples ol parallel reavtioN
). (a) Explan the term Selethityed
ples In whish conditon
(b) DescTibe sp te d holdug tmle t h utable
space time and hold1ng t Ie are cyual n

BIRSA INSTITUTE OF TECHNOLOGY (BIT) SINDRI, DILANBAL

CHEMICAL ENGINEERING DEPARTMENT