tubular flow reactor

CPE554 Universiti Teknologi MARA

Exp/Tubular Flow Reactor 1

EXPERIMENT 1: Pulse Input in a Tubular Flow Reactor

OBJECTIVE:

To examine the effect of a pulse input in a tubular flow reactor.

To construct a residence time distribution (RTD) function for the tubular flow reactor.

PROCEDURES:

1. Perform the general start-up procedures.

2. Open valve V9 and switch on pump P1.

3. Adjust pump P1 flow controller to give a constant flow rate of de-ionized water into the reactor

R1 at approximately 700 ml/min at FI-01.

4. Let the de-ionized water to continue flowing through the reactor until the inlet (QI-01) and

outlet (QI-02) conductivity values are stable at low levels. Record both conductivity values.

5. Close valve V9 and switch off pump P1.

6. Open valve V11 and switch on pump P2. Start the timer simultaneously.

7. Adjust pump P2 flow controller to give a constant flow rate of salt solution into the reactor R1 at

700 ml/min at FI-02.

8. Let the salt solution to flow for 1 minute, then reset and restart the timer. This will start the

time at the average pulse input.

9. Close valve V11 and switch off pump P2. Then, quickly open valve V9 and switch on pump P1.

10. Make sure the de-ionized water flow rate is always maintained at 700 ml/min by adjusting P1

flow controller.

11. Start recording both the inlet (QI-01) and outlet (QI-02) conductivity values at regular intervals

of 30 seconds.

12. Continue recording the conductivity values until all readings are almost constant and approach

the stable low level values.

Analysis and Discussion

1. Use the sample table in Appendix B for data collection.

2. Plot the outlet conductivity values vs time to obtain a C(t) curve.

3. Calculate the value of the integral . Use any suitable numerical method. Do not

include the integral below the stable low level value.

4. Divide each value of C(t) with the integral to obtain a value of E(t),

5. Plot E(t) as a function of time. This is the residence time distribution (RTD) function for the

reactor.

6. Compare the RTD function plot with Experiment 2.

7. Calculate the following:

a) Mean residence time, tm =

b) Second moment, Variance,σ2

=

c) Third moment, Skewness,s3



EXPERIMENT 2: Step Change Input in a Tubular Flow Reactor

OBJECTIVE:

To examine the effect of a step change input in a tubular flow reactor.

To construct a residence time distribution (RTD) function for the tubular flow reactor.

PROCEDURES:

1. Perform the general start-up procedures.

2. Open valve V9 and switch on pump P1.

3. Adjust pump P1 flow controller to give a constant flow rate of de-ionized water into the reactor

R1 at approximately 700 ml/min at FI-01.

4. Let the de-ionized water to continue flowing through the reactor until the inlet (QI-01) and

outlet (QI-02) conductivity values are stable at low levels. Record both conductivity values.

5. Close valve V9 and switch off pump P1.

6. Open valve V11 and switch on pump P2. Start the timer simultaneously.

7. Record both the inlet (QI-01) and outlet (QI-02) conductivity values at regular intervals of 30

seconds.

8. Continue recording the conductivity values until all readings are almost constant.

Analysis and Discussion

1. Use the sample table in Appendix B for data collection.

2. Plot the outlet conductivity values vs time to obtain a C(t) curve.

3. Divide each value of C(t) with the final constant value, C0 and differentiate it against time to

obtain a value of E(t). Use any suitable numerical method.

4. Plot E(t) as a function of time. This is the residence time distribution (RTD) function for the

reactor.

5. Compare the RTD function plot with Experiment 1.

6. Calculate the following:

a) Mean residence time, tm =

b) Second moment, Variance,σ2

=

c) Third moment, Skewness,s3



Preparation of Calibration Curve for Conversion vs. Conductivity

The reaction to be studied is the saponification reaction of ethyl acetate Et(Ac) and sodium hydroxide

NaOH. Since this is a second order reaction, the rate of reaction depends on both concentrations of

Et(Ac) and NaOH. However, for analysis purposes, the reaction will be carried out using equimolar feeds

of Et(Ac) and NaOH solutions with the same initial concentrations. This ensures that both concentrations

are similar throughout the reaction.

NaOH + Et(Ac) àNa(Ac) + EtOH

The following procedures will calibrate the conductivity measurements of conversion values for the

reaction between 0.1 M ethyl acetate and 0.1 M sodium hydroxide:

PROCEDURES:

1. Prepare the following solutions:

a) 1 liter of sodium hydroxide, NaOH (0.1 M)

b) 1 liter of sodium acetate, Na(Ac) (0.1 M)

c) 1 liter of deionised water, H2

2. Determine the conductivity and NaOH concentration for each conversion values by mixing

the following solutions into 100 ml of deionised water:

a) 0% conversion: 100 ml NaOH

b) 25% conversion: 75 ml NaOH + 25 ml Na(Ac)

c) 50% conversion: 50 ml NaOH + 50 ml Na(Ac)

d) 75% conversion: 25 ml NaOH + 75 ml Na(Ac)

e) 100% conversion: 100 ml Na(Ac)

ANALYSIS AND DISCUSSION:

1. Record all data in the sample table in Appendix A.

2. Plot the calibration curve of conductivity vs conversion. Determine the slope and y-axis

intercept.



Back Titration Procedures for Manual Conversion Determination

It is advisable to carry out manual conversion determination on experiment samples to verify the

conductivity measurement values. The following procedures will explain the method to carry out back

titration on the samples. It is based on the principle of quenching the sample with excess acid to stop

any further reactions, then back titrating with a base to determine the amount of unreacted acid.

PROCEDURES:

1. Fill up a burette with 0.1 M NaOH solution.

2. Measure 10 ml of 0.25 M HCl in a flask.

3. Obtain a 50 ml sample from the experiment and immediately add the sample to the HCl in

the flask to quench the saponification reaction.

4. Add a few drops of pH indicator into the mixture.

5. Titrate the mixture with NaOH solution from the burette until the mixture is neutralized.

Record the amount of NaOH titrated.

ANALYSIS AND DISCUSSION:

NaOH + HCl à NaCl + H2O

tubular flow reactor

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