CKB 20104 Reaction Engineering UniKL MICET Experiment 2a Effect of RTD On The Reaction in CSTR Full Lab Report
CKB 20104 Reaction Engineering UniKL MICET Experiment 2a Effect of RTD On The Reaction in CSTR Full Lab Report
CKB 20104 Reaction Engineering UniKL MICET Experiment 2a Effect of RTD On The Reaction in CSTR Full Lab Report
1.0
Reaction
in CSTR
SUMMARY
Continuous stirred-tank reactors (CSTRs) composed of a reactor and a mixer such
as a stirrer, a turbine wing or a propeller. This reactor is free to enter or exit the system,
which operate on a steady-state basis, where the conditions in the reactor do not change
with time. This flow reactor is used primarily in the study of the kinetics of
heterogeneous reactions. Reactants are continuously introduced into the reactor, while
products are continuously removed. CSTRs are very well mixed, so the contents have
relatively uniform properties such as temperature, density. Also, conditions in the
reactor's exit stream are the same as those inside the tank. The objectives of this
experiment of saponification reaction between NaOH and Et(Ac) are to determine the
effect of residence time, on the extent of conversion and to determine the reaction rate,rA. The experiment runs with 30L of 0.1 M Sodium Hydroxide, NaOH and 30L of 0.1 M
Ethyl Acetate, Et(Ac) at flowrate 200 mL/min and 400 mL/min. Based on the data
obtained by the experiment in Appendix B, it can say that the residence time, is
decreasing as the flowrate increase. From the graph plotted in Figure 1, it can be seen that
the conversion,X (%) versus reaction time,t (min) for flow rate 400mL/min is higher than
200mL/min where it can conclude that the conversion,X (%) is increases as the Reaction
Time,t (min) increase. A plot of the experimental data in Figure 1 of Calibration curve of
Concentration of NaOH (M) versus Conductivity (mS/cm) which is a straight line in
which its give equation y=140x + 4. The order of reaction of this experiment is second
order. From calculation, at 200mL/min, the rate constant,k is 0.32 dm3/mol.min and rate
of reaction,-rA is 2.88001 x 10-4 mol/dm3.min while at 400mL/min the rate constant,k is
7.95 dm3/mol.min and rate of reaction,-rA is 5.0861 x 10-4 mol/dm3.min. The objectives of
study are successfully achieved.
Reaction
in CSTR
Graph of Conversion,X (%) versus Reaction Time,t (min) for the different flow rate of 200mL/min and 400mL/min
100.0000
90.0000
80.0000
70.0000
60.0000
Conversion,X (%)
200 mL/min
50.0000
400 mL/min
40.0000
30.0000
20.0000
10.0000
0.0000
0 10 20 30 40 50 60
Reaction time,t (min)
Figure 1 Graph of Conversion,X (%) versus Reaction Time,t (min) for the different flow
rate of 200mL/min and 400mL/min
Reaction
in CSTR
f(x) = 140x + 4
10.0 R = 0.99
9.0
8.0
7.0
Conductivity (mS/cm)
6.0
5.0
4.0
3.0
2.0
1.0
0.0
0.0000 0.0100 0.0200 0.0300 0.0400 0.0500 0.0600
Concentration of NaOH (M)
Reaction
in CSTR
0.3200
min. M
= 0.32 dm3/mol.min
7.9470
min. M
= 7.95 dm3/mol.min
0.3200
min. M
x (0.0300 M)2
7.9470
min. M
x (0.0080 M)2
3.0
Reaction
in CSTR
to enter or exit the system, that operate on a steady-state basis, where the conditions in
the reactor don't change with time. Reactants are continuously introduced into the reactor,
while products are continuously removed. CSTRs consist of a tank, usually of constant
volume, and a stirring system to mix reactants together. Also, feed and exit pipes are
present to introduce reactants and remove products. CSTR was used to study liquid phase
reaction kinetics in a CSTR. The conversion at different residence time can be
determined. Lastly, the effect of temperature on the reaction in CSTR can be studied.
The purposed of this experiment is to find out the effect of RTD on the reaction in
a CSTR by carrying out saponification reaction between NaOH and Et(Ac) in a CSTR.
Other than that, the effect of residence time on the extent of conversion and the reaction
rate constant was determined.
The equipment was run with two different flowrate which were 200ml/L and
400ml/L. For 200ml/L flowrate, the concentration of NaOH was obtained from the
calibration curve. The highest concentration of NaOH is 0.046 M and the lowest
concentration is 0.03 M. The concentration decrease along with the increase of time. For
400ml/L flowrate, the highest concentration of NaOH is 0.021 M and the lowest
concentration of NaOH is 0.008 M.
With the obtained data, the conversion, X can be calculated. For 200ml/L flowrate
the highest conversion recorded was 34.7826% at 55th minutes. While for 400ml/L
flowrate the highest conversion recorded was 61.9048% at 40th minutes. Based on the
graph of conversion, X vs reaction time, the graph for 200ml/L the conversion increase
with reaction time. While for 400ml/L the graph increase drastically. The conversion also
increase along with reaction time, t.
Reaction
in CSTR
Residence time is the average amount of time that a particle spends in particular
system. The residence time is a representation of how long it takes for the concentration
to significantly change in the sediment. Conversion is an improve way of quantifying
exactly how far has the reaction moved, or how many moles of products are formed for
every mole of reactant consume. Rate of reaction is defined as the rate of disappearance
of reactants or the rate of formation of products. Rate of reaction can describe about how
fast a number of moles of one chemical species reaction to form another species. Rate of
reaction of each species corresponds respectively to their stoichiometric coefficient.
If the size of the system is changed, the residence time of the system will be
changed as well. The larger the system, the larger the residence time. If the inflow and
outflow are increased, the residence time of the system will be shorter. However, if the
inflow and the outflow of a system are decreased, the residence time will be longer.
4.0
Reaction
in CSTR
Conclusions
As a conclusion, it can be seen that the effect of RTD on the reaction in a CSTR affect the
saponification reaction between NaOH and Et(Ac), residence time on the extent of
conversion and the reaction rate constant. Based from the result obtained, the higher the
flow rate the shorter the time taken for the reaction to occur until it reached a constant
conductivity value. At 200L/min, the k value is 0.32 dm/mol.min while at 400mL/min is
7.95 dm/mol.min. The conversion is the highest at 400L/min, 61.9% and lowest at
200L/min, 34.78%. The average residence time is highest at 200L/min compared to other
flow rates. The residence time increase as the conversion increase.
Recommendations
There are some recommendations that are needed for improvement in order to
increase the efficiency of the result obtained. During the experiment, make sure the
solution used is measured correctly. The eyes must be perpendicular to the measuring
scale to avoid parallax error. The mixture of the reaction might not be stirred evenly as
the reaction just started at that time. Lastly, check the flow rate constantly as it needs to
approximately reach 200 L/min for a better value of conductivity. Make sure the feed
stock is sufficient so that the experiment can be conduct until the conductivity is constant.
5.0
Reaction
in CSTR
TUTORIAL
1. Discuss the advantages and disadvantages of using CSTR reactors in chemical
reaction. Describe an example of industrial applications that utilized CSTR
reactors in its process.
A continuous stirred tank reactor actually equipped with stirred tank with continuous
inflow of the reactants and outflow of the product mixture. It normally run under
unsteady state conditions and usually used for proper mixing of reactants. The reactor is
also known as mixed flow reactor. In this reactor there is no variation of concentration,
temperature and reaction rate within reactor volume.
ADVANTAGES
DISADVANTAGES
reaction.
consideration.
For
high
pressure
the
initial
as
well
as
maintenance cost.
Reaction
in CSTR
Conversion of this reactor is lower compared to plug flow reactor because a CSTR is
well mixed, and the average reaction rate will be that of the conditions of the bulk
mixture. The composition of the reactor product is also the same as that in the reactor. For
most reactions (especially equilibrium reactions) the rate of reaction decreases with
increasing concentrations of final product (and decreasing concentrations of reagent).The
reaction desired is to get high concentration of final product from the reactor but in order
to achieve that it will cause with lower average reaction rate in the reactor. In a plug flow
reactor, the rate is not constant. In the first section of the reactor, the rates are high (high
concentration of feed and low concentration of product). As the material goes through the
reactor the rates drop. The average rate is still higher and hence the conversion for a
given reactor volume is also better.
Due to the bigger reactor size compared to PFR, it will provide a longer residence
time.The residence time distribution (RTD) of a chemical reactor is a probability
distribution function that describes the amount of time a fluid element could spend inside
the reactor. Chemical engineers use the RTD to characterize the mixing and flow within
reactors and to compare the behavior of real reactors to their ideal models. This is useful,
not only for troubleshooting existing reactors, but in estimating the yield of a given
reaction and designing future reactors.
CSTR is also more preferred compared to PFR because it low cost of construction
compared to PFR. Due to the low cost, the company which preferred CSTR will have no
problem due to the budgetary control in order to run the maintenance jobs towards the
equipment.
CSTR are commonly used in biological processes, such as cell cultures.It can be used
for high density animal cell culture in research or production.Fermentors are CSTRs used
in biological processes in many industries, such as brewing, antibiotics, and waste
treatment. In fermentors, large molecules are broken down into smaller molecules, with
alcohol produced as a by-product
Reaction in CSTR
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2. Write a one-paragraph summary of any journal article that studies chemical reaction in a
CSTR. The article must have been published within the last 5 years. Explain on the CSTR
reactor used in the study and its significance to the study done.
Article:
A continuous stirred tank reactor (CSTR) was used to study the gas-phase reaction between
Hydroxyl radicals (HO) and toluene. HO was generated by the in situ photolysis of nitrous acid.
Flow reactor operation at steady-state conditions with a residence time of 20 min allowed
investigation of primary and very rapid secondary reactions. CSTR and batch reactor
experiments were also performed with selected products. Both gas-phase and aerosol products
were identified by chromatography and mass spectroscopy, with total product yields between 55
and 75% of reacted carbon. Toluene reaction products included cresols, nitrocresols,
nitrotoluenes, 3,5-dinitrotouluene, benzaldehyde, benzyl nitrate, nitrophenols, methyl-pbenzoquinone, glyoxal, methylglyoxal, formaldehyde, methyl nitrate, PAN, and CO. The fraction
of HO methyl hydrogen abstraction was calculated to be 0.13 0.04. The ratio of reaction rate
constants for nitrotoluene versus cresol formation from the HO-adduct was calculated to be
about 3.3 104. Also, the ratio of cresol formation versus O2 addition to the HO -adduct was
estimated to be 0.5 for atmospheric conditions. Comparisons of these measurements with
previous values and the implications with respect to photochemical kinetics modeling of the
atmosphere are discussed.
6.0
Reaction in CSTR
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REFERENCES
1. Fogler S. H., Elements of Chemical Reaction Engineering (3rd ed.) Englewood Cliffs,
NJ: Prentice-Hall, New York, 1998.
2. Hill C. G. Jr., An Introduction to Chemical Engineering Kinetics and Reactor Design,
John Wiley & Sons Inc, New York, 1977.
3. Perry, Robert H. and Don W. Green. Perry's Chemical Engineers' Handbook. 7th ed,
McGraw-Hill Inc, New York, 1997, p7-19.
4. Trambouze, P., Van L. H. and Wauquier J.P., Chemical Reactors, Gulf Publishing
Company, Houston, 1988.
5. Walas, S. M., Chemical Process Equipment: Selection and Design.
Butterworth- Heinemann, Boston, 1990.
6. Reactor Design and Types.(2015) Continuous stirred tank reactor(CSTR).[online].
[Accessed 2 April,2016]. Available from World Wide Web:
http://chemicalfunda.com/reactors-design-and-types-its-advantages-and-disadvantages/
7. Continuous stirred tank reactor.(1985) International Journal of Chemical Kinetics.
[online].[Accessed 2 April,2016]. Available from World Wide Web :
http://onlinelibrary.wiley.com/doi/10.1002/kin.550170903/full
8. http://www.academia.edu/3635145/Residence_Time_Distribution_Data
7.0
APPENDICES
APPENDIX A
Reaction in CSTR
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Conductivity
of NaOH (M)
(mS/cm)
0.0500
10.7
0.0375
9.7
0.0250
7.5
0.0125
5.6
0.0000
4.0
f(x) = 140x + 4
10.0 R = 0.99
9.0
8.0
7.0
Conductivity (mS/cm)
6.0
5.0
4.0
3.0
2.0
1.0
0.0
0.0000 0.0100 0.0200 0.0300 0.0400 0.0500 0.0600
Concentration of NaOH (M)
Reaction in CSTR
Sample calculation
For flow rate = 200mL/min
1. Time = 0 min, Temperature = 31.1C
Total flow rate of solutions, F0 (mL/min)
= FNaOH + FEt
= 193mL/min + 201mL/min
= 394 mL/min
= FNaOH + FEt
= 190mL/min + 195mL/min
= 385 mL/min
= FNaOH + FEt
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Reaction in CSTR
= 189mL/min + 190mL/min
= 379 mL/min
4. Time = 15 min, Temperature = 31.8C
Total flow rate of solutions, F0 (mL/min)
= FNaOH + FEt
= 180mL/min + 187mL/min
= 367 mL/min
= FNaOH + FEt
= 175mL/min + 186mL/min
= 361 mL/min
= FNaOH + FEt
= 173mL/min + 183mL/min
= 356 mL/min
= FNaOH + FEt
= 166mL/min + 184mL/min
= 350 mL/min
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Reaction in CSTR
= FNaOH + FEt
= 162mL/min + 183mL/min
= 345 mL/min
= FNaOH + FEt
= 160mL/min + 184mL/min
= 344 mL/min
= FNaOH + FEt
= 165mL/min + 180mL/min
= 345 mL/min
= FNaOH + FEt
= 163mL/min + 181mL/min
= 344 mL/min
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Reaction in CSTR
= FNaOH + FEt
= 408mL/min + 383mL/min
= 791 mL/min
= FNaOH + FEt
= 404mL/min + 396mL/min
= 800 mL/min
= FNaOH + FEt
= 395mL/min + 396mL/min
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Reaction in CSTR
= 791 mL/min
4. Time = 15 min, Temperature = 32.6C
Total flow rate of solutions, F0 (mL/min)
= FNaOH + FEt
= 400mL/min + 384mL/min
= 784 mL/min
= FNaOH + FEt
= 396mL/min + 391mL/min
= 787 mL/min
= FNaOH + FEt
= 392mL/min + 383mL/min
= 775 mL/min
= FNaOH + FEt
= 382mL/min + 386mL/min
= 768 mL/min
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Reaction in CSTR
= FNaOH + FEt
= 376mL/min + 378mL/min
= 754 mL/min
= FNaOH + FEt
= 394mL/min + 400mL/min
= 794 mL/min
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Reaction in CSTR
P a g e | 13
10 000 mL
394 mL/min
= 25.38min
10 000 mL
3 85 mL /min
= 25.97min
10 000 mL
3 79 mL /min
= 26.39min
3 67 mL /m
10 000 mL
=
= 27.25min
Reaction in CSTR
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10 000 mL
3 61 mL /min
= 27.70min
10 000 mL
3 56 mL /min
= 28.09min
10 000 mL
3 50 mL/min
= 28.57min
10 000 mL
3 45 mL/min
= 28.99min
10 000 mL
3 44 mL /min
= 29.07min
10 000 mL
3 45 mL/min
= 28.99min
10 000 mL
3 44 mL /min
= 29.07min
Reaction in CSTR
P a g e | 13
For 400mL/min
1. Time = 0 min, Temperature = 32.6C
Volume CSTR (mL)
mL
Residence time, =
F 0(
)
min
2. Time = 5 min, Temperature = 32.6C
Volume CSTR (mL)
mL
Residence time, =
F 0(
)
min
3. Time = 10 min, Temperature = 32.6C
Volume CSTR (mL)
mL
Residence time, =
F 0(
)
min
4. Time = 15 min, Temperature = 32.6C
Volume CSTR (mL)
mL
Residence time, =
F 0(
)
min
5. Time = 20 min, Temperature = 32.6C
Volume CSTR (mL)
mL
Residence time, =
F 0(
)
min
6. Time = 25 min, Temperature = 32.6C
10 000 mL
791 mL /min
= 12.64min
10 000 mL
800 mL/min
= 12.50min
10 000 mL
791 mL /min
= 12.64min
10 000 mL
784 mL/min
= 12.76min
10 000 mL
787 mL /min
= 12.71min
Reaction in CSTR
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10 000 mL
775 mL /min
= 12.90min
10 000 mL
768 mL /min
= 13.02min
10 000 mL
754 mL/min
= 13.26min
10 000 mL
794 mL/min
= 12.59min
Reaction in CSTR
P a g e | 13
Reaction in CSTR
For 400mL/min
1. Time = 0 min, Temperature = 32.6C
Concentration of NaOH, CNaOH (M) = 0.0210 M
2. Time = 5 min, Temperature = 32.6C
Concentration of NaOH, CNaOH (M) = 0.0200 M
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Reaction in CSTR
P a g e | 13
Conversion,X (%)
For 200mL/min
1. Time = 0 min, Temperature = 31.1C
C NaOH ( t=0 ) C
NaOH (t)
C NaOH (t=0 )
X=
100
0.0460 M 0.0460 M
0.0460 M
x 100% = 0 %
C NaOH ( t=0 ) C
NaOH (t)
C NaOH (t=0 )
X=
100
Reaction in CSTR
0.0460 M 0.0441 M
0.0460 M
P a g e | 13
x 100% = 4.1304 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0460 M 0.0439 M
0.0460 M
x 100% = 4.5652 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0460 M 0.0420 M
0.0460 M
x 100% = 8.6957 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0460 M 0.0400 M
0.0460 M
x 100% = 13.0435 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0460 M 0.0390 M
0.0460 M
x 100% = 15.2174 %
C NaOH ( t=0 ) C
NaOH (t)
C NaOH (t=0 )
X=
100
Reaction in CSTR
0.0460 M 0.0362 M
0.0460 M
P a g e | 13
x 100% = 21.3043 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0460 M 0.0350 M
0.0460 M
x 100% = 23.9130 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0460 M 0.0330 M
0.0460 M
x 100% = 28.2609 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0460 M 0.0310 M
0.0460 M
x 100% = 32.6087 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0460 M 0.0300 M
0.0460 M
x 100% = 34.7826 %
Reaction in CSTR
P a g e | 13
For 400mL/min
1. Time = 0 min, Temperature = 32.6C
C NaOH ( t=0 ) C
NaOH (t)
C NaOH (t=0 )
X=
100
0.0210 M 0.0210 M
0.0210 M
x 100% = 0 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0210 M 0.0200 M
0.0210 M
x 100% = 4.7619 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0210 M 0.0170 M
0.0210 M
x 100% = 19.0476 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0210 M 0.0150 M
0.0210 M
x 100% = 28.5714 %
C NaOH ( t=0 ) C
NaOH (t)
C NaOH (t=0 )
X=
100
Reaction in CSTR
0.0210 M 0.0140 M
0.0210 M
P a g e | 13
x 100% = 33.3333 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0210 M0.0125 M
0.0210 M
x 100% = 40.4762 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0210 M 0.0110 M
0.0210 M
x 100% = 47.6190 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0210 M 0.0090 M
0.0210 M
x 100% = 57.1429 %
NaOH (t)
C NaOH (t=0 )
X=
100
0.0210 M 0.0080 M
0.0210 M
x 100% = 61.9048 %