January 2016
EXPERIMENT NO: 2
CONTINUOUS STIRRED TANK REACTOR
OBJECTIVES
1). To study liquid phase reaction kinetics in a CSTR 2). To determine the conversion at different residence time. 3). To study the effect of temperature on the reaction in CSTR.
Keywords: CSTR; residence time; Mixing; Saponification kinetics; Activation energy
2.0
GENERAL DESCRIPTION 2.1
Description & Assembly Before operating the unit and running experiments, you must familiarize yourself with the unit’s components. Please Please refer to Figure 1 to understand the process. All glass components of the QVF Continuous Stirred Tank
January 2016
5.
Condenser (W1) 2
Coil heat exchanger, area 0.2 m Max coolant pressure of 2 bar with allowable temperature difference of 150°C 6.
Receiving vessel (B3) 100 L rectangular tank
7.
Instrumentation Flow measurement (FI-301, FI-302) Temperature measurement (TI-101) Conductivity measurement (QI-401)
2.2
Safety Considerations 1.
The unit must be operated under the supervision of an authorized staff that has been properly trained to handle the unit.
2.
All operating instructions supplied with the unit must be carefully read and understood before attempting to operate the unit.
3.
Feed stock which severely affects PTFE, PFA and borosilicate glass are not to be used.
4.
The system should not be subjected to shock, sudden impact, vibration, additional load, or permanent external action of aggressive vapours.
5.
Always check and rectify any leakages.
January 2016
Vent
V1
V6
Cooling Water B1
B2
W1
Cooling Water
V13 HS 1 Q1 401
M
TI 101
V2
V7 FI 301
FI 302
V5
V10
V3
R1
V8 V3
V11 V4 P1
V9 P2
M
M
HS 2
HS 3
V12 B3
T1
Figure 1: Continuous Stirred Tank Reactor (CSTR)
______________________________________________________________________________________ CKD 20002 (REACTOR TECHNOLOGY), Experiment 2: Continuous Stirred Tank Reactor
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January 2016
3.0
OPERATING PROCEDURES 3.1
General Start-up Procedures 1.
Prepare the following solutions: a) 25 L of sodium hydroxide, NaOH (0.1 M) b) 25 L of ethyl acetate, Et(Ac) (0.1 M)
2.
Ensure that all valves are initially closed.
3.
Charge the feed vessels as follows: a) Open the charge port caps for vessels B1 and B2. b) Carefully pour the NaOH solution into vessel B1 and the Et(Ac) solution into vessel B2. c) Close the charge port caps for both vessels.
4.
Turn on the power for the control panel.
5.
Check that there is sufficient water in the thermostat T1 tank. Refill as necessary.
6.
Open cooling water valve V13 and let the cooling water flow through the condenser W1 (*Exp B only).
7.
Switch on the thermostat T1 and set the water temperature to desired temperature (*Exp B only).
8.
Open valve V2, V7 and V11.
9.
The unit is now ready to be used for an experiment.
January 2016
5.
Readjust the valves V5 and V10 to give a flow rate of about 100 mL/min. Make sure that both flow rates are the same.
6.
Switch ON the stirrer M1.
7.
Start the timer simultaneously.
8.
Record the conductivity value at Q1-401 for every 5 minutes until it does not change over time. This is to ensure that the reactor has reached steady state.
9.
End the experiment when the conductivity values do not change significantly over time (30 minutes).
10. Repeat the experiment (steps 3 to 9) for different residence times by adjusting the feed flow rates of NaOH and Et(Ac) to about 200 mL/min and 300 mL/min. Make sure that both flow rates are maintained the same. 11. Perform the general shut-down procedures.
ANALYSIS AND DISCUSSION: 1.
Use the table for data collection at Appendix B.
2.
By using the data in the sample table in Appendix A, i)
Plot the calibration curve of Concentration of NaOH (M) vs Conductivity. Determine the slope and y-axis intercept.
ii)
Plot the calibration curve of Conversion vs Conductivity. Determine the slope and y-axis intercept.
# Use the equation (i) and (ii) to determine the value of concentration of
January 2016
Rate of reaction, r A kC A 2
4.2
EXPERIMENT B: The Effect of Temperature on the Reaction in a CSTR OBJECTIVES: To determine the effect of temperature on the extent of conversion. PROCEDURES: 1.
Perform the general start-up procedures.
2.
Set the thermostat T1 temperature to 40°C.
4.
Open valves V5 and V10.
5.
Switch on both pumps P1 and P2 simultaneously.
6.
Let the reactor fill up with both solutions until it is just about to 1/2 full.
7.
Readjust the valves V5 and V10 to give a flow rate of 100 mL/min. Make sure that both flow rates are the same.
8.
Switch ON the stirrer M1.
9.
Start the timer simultaneously.
10. Record the conductivity value at Q1-401 for every 5 minutes until it does not change over time. This is to ensure that the reactor has reached steady state. 10. End the experiment when the conductivity values do not change significantly over time (30 minutes).
January 2016
5.
Calculate the Saponification reaction’s activation energy, E and frequency factor (A) from the slope and intercept values using the Arrhenius equation.
AeE / RT , (R = 8.3014 J/mol.K)
kT
lnk
5.0
lnA
Ea R
1 T
i)
Plot a graph of ‘ln k’ vs ‘1/T’ (T in Kelvin unit).
ii)
Determine activation energy (E a) and frequency factor (A) from the slope and intercept values.
TUTORIAL 1.
What will be the effect of flow rates and temperature on the reaction rate and rate constant?
2.
Why the CSTR is so special compared to Batch & Tubular (PFR) reactor?
3.
Discuss the advantages and disadvantages of using CSTR reactors in chemical reaction.
January 2016
Solution Mixtures Conversion
Concentration of NaOH (M)
Conductivity (mS/cm)
0.1 M NaOH
0.1 M Na(Ac)
H 2O
0%
100 mL
–
100 mL
0.0500
10.7
25%
75 mL
25 mL
100 mL
0.0375
9.7
50%
50 mL
50 mL
100 mL
0.0250
7.5
75%
25 mL
75 mL
100 mL
0.0125
5.6
100%
–
100 mL
100 mL
0.0000
4.0
January 2016
APPENDIX B RESULTS FOR EXPERIMENTS A & B Reactor volume
= _____ L
Concentration of NaOH in feed vessel = _____ M
Flowrate
=
_____ mL/min
Temperature
=
_____ C
o
Concentration of Et(Ac) in feed vessel = _____ M
Time
Temperature (°C) TI-101
Flow rate of NaOH (mL/min) FI-301
Flow rate of Et(Ac) (mL/min) FI-302
Total flow rate of solutions, F0 (mL/min)
Residence time, (min)
Conductivity (mS/cm) QI-401
Concentration of NaOH, CNaOH (M)
Conversion, X (%)
0 5 10 15 20 25 30
_ ______________________________________________________________________________ CKD 20002: Reactor Technology, Experiment 2: Continuous Stirred Tank Reactor
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January 2016
RESULTS FOR EXPERIMENTS A & B Reactor volume
= _____ L
Concentration of NaOH in feed vessel = _____ M
Flowrate
=
_____ mL/min
Temperature
=
_____ C
o
Concentration of Et(Ac) in feed vessel = _____ M
Time
Temperature (°C) TI-101
Flow rate of NaOH (mL/min) FI-301
Flow rate of Et(Ac) (mL/min) FI-302
Total flow rate of solutions, F0 (mL/min)
Residence time, (min)
Conductivity (mS/cm) QI-401
Concentration of NaOH, CNaOH (M)
Conversion, X (%)
0 5 10 15 20 25 30
_ ______________________________________________________________________________ CKD 20002: Reactor Technology, Experiment 2: Continuous Stirred Tank Reactor
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January 2016
RESULTS FOR EXPERIMENTS A & B Reactor volume
= _____ L
Concentration of NaOH in feed vessel = _____ M
Flowrate
=
_____ mL/min
Temperature
=
_____ C
o
Concentration of Et(Ac) in feed vessel = _____ M
Time
Temperature (°C) TI-101
Flow rate of NaOH (mL/min) FI-301
Flow rate of Et(Ac) (mL/min) FI-302
Total flow rate of solutions, F0 (mL/min)
Residence time, (min)
Conductivity (mS/cm) QI-401
Concentration of NaOH, CNaOH (M)
Conversion, X (%)
0 5 10 15 20 25 30
_ ______________________________________________________________________________ CKD 20002: Reactor Technology, Experiment 2: Continuous Stirred Tank Reactor
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