attachment_1428685327598_bp 101 b

UNIVERSITI TEKNOLOGI MARAFAKULTI KEJURUTERAAN KIMIA

CHEMICAL ENGINEERING LABORATORY III(CHE574)

No. Title Allocated Marks (%) Marks

1 Abstract/Summary 5

2 Introduction 5

3 Aims 5

4 Theory 5

5 Apparatus 5

6 Methodology/Procedure 10

7 Results 10

8 Calculations 10

9 Discussion 20

10 Conclusion 5

11 Recommendations 5

12 Reference / Appendix 5

13 Supervisor’s grading 10

TOTAL MARKS 100

Checked by :

Date :

NAME AND STUDENT NO : NUR SYAFIQAH BINTI FADALY (2012662222)GROUP : EH 220 4AEXPERIMENT : TUBULAR FLOW REACTOR (BP 101-B) DATE PERFORMED : 6/05/2014SEMESTER : 4PROGRAMME / CODE : CHE 574SUBMIT TO : DR JEFRI JAAPAR

TABLE OF CONTENT

Page

1 ABSTRACT 3

2 INTRODUCTION 4

3 OBJECTIVE 5

4 THEORY 5

5 APPARATUS 6

6 PROCEDURE 7

7 RESULT AND CALCULATION 9

8 DISCUSSION 21

9 CONCLUSION 22

10 RECOMMENDATION 22

11 REFERENCES 23

12 APPENDICES

2

1 ABSTRACT

This experiment has been conducted on 6th May 2014. The experiment is conducted to

achieve the objective that has been considered which is to examine the effect of pulse input and

step change input in tubular flow reactor and to construct the residence time distribution function

by using tubular machine. Based on the experiment, two experiment were conducted which is

pulse input experiment and step change input experiment. In the pulse input experiment, the flow

rate was set up at 700 m3s-1 and let it for one minute before reading taken every 30 seconds until

the conductivity reading is 0.0. In the other hand, the step change input experiment, the

conductivity were observe every 30 seconds until the reading at Q2 is constant.

3

2 INTRODUCTION

A tubular reactor is a vessel through which flow is continuous, usually at steady state,

and configured so that conversion of the chemicals and other dependent variables are functions

of position within the reactor rather than of time. Flow in tubular reactors can be laminar , as

with viscous fluids in small-diameter tubes, and greatly deviate from ideal plug-flow behavior, or

turbulent, as with gases.

In an ideal plug flow reactor, a pulse of tracer injected at the inlet would not undergo any

dispersion as it passed through the reactor and would appear as a pulse at the outlet. The degree

of dispersion that occurs in a real reactor can be assessed by following the concentration of tracer

versus time at the exit. This procedure is called the stimulus-response technique.

High temperature reactions Residence Time Distribution (RTD) analysis is a very

efficient diagnosis tool that can be used to inspect the malfunction of chemical reactors.

Residence time distributions are measured by introducing a non-reactive tracer into the system at

the inlet. The concentration of the tracer is changed according to a known function and the

response is found by measuring the concentration of the tracer at the outlet. The selected tracer

should not modify the physical characteristics of the fluid (equal density, equal viscosity) and the

introduction of the tracer should not modify the hydrodynamic conditions. In general, the change

in tracer concentration will either be a pulse or a step.

The residence time distribution of a real reactor deviated from that of an ideal reactor,

depending on the hydrodynamics within the vessel. A non-zero variance indicates that there is

some dispersion along the path of the fluid, which may be attributed to turbulence, a non-

uniform velocity profile, or diffusion. If the mean of the curve arrives earlier than the

expected time it indicates that there is stagnant fluid within the vessel. If the residence time

distribution curve shows more than one main peak it may indicate channeling, parallel paths to

the exit, or strong internal circulation.

4

3 OBJECTIVE

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

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

4 THEORY

A tubular reactor is a vessel through which flow is continuous, usually at steady state,

and configured so that conversion of the chemicals and other dependent variables are functions

of position within the reactor rather than of time. In the ideal tubular reactor, the fluids flow as

if they were solid plugs or pistons, and reaction time is the same for all flowing material at any

given tube cross section. Tubular reactors resemble batch reactors in providing initially high

driving forces, which diminish as the reactions progress down the tubes. Tubular reactor are

often used when continuous operation is required but without back-mixing of products and

reactants.

Flow in tubular reactors can be laminar, as with viscous fluids in small-diameter tubes,

and greatly deviate from ideal plug-flow behavior, or turbulent, as with gases .Turbulent flow

generally is preferred to laminar flow, because mixing and heat transfer are improved. For slow

reactions and especially in small laboratory and pilot-plant reactors, establishing turbulent flow

can result in inconveniently long reactors or may require unacceptably high feed rates.

Tubular reactor is specially designed to allow detailed study of important process. The

tubular reactor is one of three reactor types which are interchangeable on the reactor service unit.

the reactions are monitored by conductivity probe as the conductivity of the solution changes

with conversion of the reactant to product. This means that the inaccurate and inconvenient

process of titration, which was formally used to monitor the reaction progress, is no longer

necessary.

5

The residence-time of an element of fluid leaving a reactor is the length of time spent by

that element within the reactor. For a tubular reactor, under plug-flow conditions, the residence-

time is the same for all elements of the effluent fluid. (K. G. Denbigh) The procedure would be

to carry out experiments with tubular reactor at varying feed rates, measuring the extent of

reaction of the stream leaving the reactor. One possible method might to add ‘inert’ gas to the

acetaldehyde vapor in such quantity that the change in density between entry and exit of the

reactor could be neglected. In that case, the batch reactor time and the residence-time would both

be equal to the space-time.

5 APPARATUS

1. Tubular flow reactor (BP 101-B)2. Deionized water3. 0.025M sodium chloride, NaCl4. Ethyl acetate

6

6 PROCEDURE

6.1 General start-up procedures

1. All valves are initially closed except valve V7.

2. 20 liter of 0.025M sodium chloride, NaCl is prepared.

3. The feed tank B2 is filled with the NaCl solution.

4. The power is turned on for the control panel.

5. The water de-ionizer is connected to the laboratory water supply. Valve V3 is opened and

feed tank B1 is filled with the deionized water. Valve V3 is closed.

6. Valves V2 and V10 are opened. Pump P1 is switched on. P1 flow controller is adjusted to

obtain a flow rate of approximately 700 mL/min at flow meter F1-01. The conductivity

display is observed at low value then valve V10 is closed and pump P1 is switched off.

7. Valves V5 and V12 are switched on. Pump P2 is switched on. P2 flow controller is

adjusted to obtain a flow rate of approximately 700 mL/min at flow meter F1-02. Valves

V12 is closed and pump P2 is switched off.

6.2 Experiment 1: Pulse input in a tubular flow reactor

1. The general start-up procedure is performed.

2. Valve V9 is opened and pump P1 is switch on.

3. Pump P1 flow controller is adjusted to give a constant flow rate of de-ionized water into

the reactor R1 at approximately 700 ml/min at Fl-01.

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

and outlet (Ql-02) conductivity values are stable at low levels. Both conductivities values

are recorded.

5. Valve V9 is closed and pump P1 is switch off.

6. Valve V11 is opened and Pump P2 is switch on. The timer is started simultaneously.

7. Pump P2 flow controller is adjusted to give a constant flow rate of salt solution into the

reactor R1 at 700 ml/min at Fl-02.

7

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. Valve V11 is closed and pump P2 is switch off. Then, open valve V9 quickly and

pumpP1 is switch on.

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

adjusting P1 flow controller.

11. Both the inlet (Ql-01) and outlet (Ql-02) conductivity a value at regular intervals of

30seconds is start recorded.

12. The conductivity values is continue recording until all readings are almost constant and

approach the stable low level values.

6.3 Experiment 2: Step change input in a tubular flow reactor

1. The general start-up procedure is performed.

2. Valve V9 is opened and pump P1 is switch on.

3. Pump P1 flow controller is adjusted to give a constant flow rate of de-ionized water into

the reactor R1 at approximately 700 ml/min at Fl-01.

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

and outlet (Ql-02) conductivity values are stable at low levels. Both conductivities values

are recorded.

5. Valve V9 is closed and pump P1 is switch off.

6. Valve V11 is opened and Pump P2 is switch on. The timer is started simultaneously.

7. Both the inlet (Ql-01) and outlet (Ql-02) conductivity a value at regular intervals of

30seconds is start recorded.

8

8. The conductivity values is continue recording until all readings are almost constant.

7 RESULT AND CALCULATION

Experiment 1: Pulse Input in a Tubular Flow Reactor

Flow rate = 700 mL/min (De-ionized water)

Time (min) Conductivity(mS/cm)

Inlet Outlet

0.0 0.0 0.0

0.5 0.3 0.0

1.0 0.0 0.8

1.5 0.0 1.9

2.0 0.0 1.1

2.5 0.0 0.2

3.0 0.0 0.0

3.5 0.0 0.0

9

0 0.5 1 1.5 2 2.5 3 3.5 40

0.20.40.60.81

1.21.41.61.82

Oulet Conductivity (mS/cm) VS Time (min)

Time (min)

Oul

et C

ondu

ctivi

ty (m

S/cm

)

∫0

∞

C ( t ) dt= Area under the graph

Area = (t 1-t 2) [ f (t1 )+ f (t 2)2 ]

For time (0.5-1.0) minutes

Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (1.0– 0.5)[ 0+0.8

2 ]= 0.1 g .min ¿m3

For time (1.0 – 1.5) minutes

Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (1.5– 1.0)[ 0.8+1.9

2 ]= 0.675 g .min ¿m3


10

Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (2.0– 1.5)[ 1.9+1.1

2 ]= 0.75g .min ¿m3


Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (2.5– 2.0)[ 1.1+0.2

2 ]= 0.325 g .min ¿m3


Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (3.0– 2.5)[ 0.2+0.0

2 ]= 0.005 g .min ¿m3

So the total area or ∫0

4

C ( t ) dt= ( 0.1+ 0.675 + 0.75 + 0.325 + 0.005) = 1.855

g.min/m3

E ( t )= C( t)

∫0

∞

C (t )dt

For t = 0, C(t) = 0.0

E( t)=0 /1.855=0

For t = 0.5, C(t) = 0.0

E( t)=0 /1.855=0

For t = 1.0, C(t) = 0.8

E( t)=0.8 /1.855=0.431267

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For t = 1.5, C(t) = 1.9

E( t)=1.9/1.855=1.02425

For t = 2.0, C(t) = 1.1

E( t)=1.1/1.855=0.59299

For t = 2.5, C(t) = 0.2

E( t)=0.2/1.855=0.1078167

For t = 3.0, C(t) = 0.0

E( t)=0 /1.855=0

For t = 3.5, C(t) = 0.0

E( t)=0 /1.855=0

Time(min) Conductivity Oulet E(t)

0.0 0.0 0.0

0.5 0.0 0.0

1.0 0.8 0.4313

1.5 1.9 1.0242

2.0 1.1 0.5930

2.5 0.2 0.1078

3.0 0.0 0.0

3.5 0.0 0.0

Residence time distribution (RTD) function for plug flow reactor

12

0 0.5 1 1.5 2 2.5 3 3.5 40

0.2

0.4

0.6

0.8

1

1.2

E(t) VS Time(min)

Time(min)

E(t)

For time (0 – 0.5)minutes = 0

For time (0.5 -1.0)minutes

Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (1– 0.5)[ 0.4313

2 ]= 0.107825

For time (1 – 1.5) minutes

Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (1.5– 1)[ 0.4313+1.0242

2 ] = 0.363875

For time (1.5 – 2.0 )minutes

Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (2 – 1.5)[ 1.0242+0.593

2 ] = 0.4043


Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (2.5 – 2)[ 0.593+0.1078

2 ]= 0.1752

For time (2.5 -3.0) minutes

Area = (t 2−t 1¿[ E (t1+t 2 )2 ] = (3– 2.5)[ 0.1078

2 ]=0.02695

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For time (3 -3.5) minutes = 0

∫0

∞

E ( t ) dt= Total area under the graph = (0.107825 + 0.363875 + 0.4043 +

0.1752 + 0.02695 ) =1.07815

Residence time ,tm=¿ ∫0

∞

tE ( t )dt= 3.5(1.07815)= 3.773525

Time(min) Oulet Conductivity (mS/cm)

E(t) tE(t) (t-tm)2E(t)dt

(t-tm)3E(t)dt

0.0 0.0 0.0 0.0 0.0 0.0

0.5 0.0 0.0 0.0 0.0 0.0

1.0 0.8 0.4313 0.4313 3.3177 -9.2019

1.5 1.9 1.0242 1.5363 5.2940 -12.0360

2.0 1.1 0.5930 1.1860 1.8652 -3.3080

2.5 0.2 0.1078 0.2695 0.1748 -0.2227

3.0 0.0 0.0 0.0 0.0 0.0

3.5 0.0 0.0 0.0 0.0 0.0

∑ =2.1563 =3.4231 =10.6517 =-25.0926

Mean residence time, tm=¿ ∫0

∞

tE ( t )dt=¿3.4231

Second moment, variance ,σ 2 = ∫0

∞

(t−tm)2 E(t) dt

= 10.6517

14

Third moment, skewness, s3= 1

σ32 ∫

0

∞

(t−tm)3E(t) dt

=1

(3.2637)32 ¿-25.0926) = -4.2558

Experiment 2: Step Change Input in a Tubular Flow Reactor

Flow rate = 700 mL/min (De-ionized water)

Time (min) Conductivity(mS/cm)

Inlet Outlet

0.0 0.0 0.0

0.5 3.7 0.0

1.0 4.0 0.0

1.5 4.2 0.0

2.0 4.2 0.0

2.5 4.2 1.0

3.0 4.2 2.3

3.5 4.3 2.6

4.0 4.2 2.6

4.5 4.3 2.6

15

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

0.5

1

1.5

2

2.5

3

Oulet Conductivity (mS/cm) VS Time (min)

time (min)

Oul

et C

ondu

ctivi

ty (m

S/cm

)

Calculation

∫0

∞

C (t ) dt= Area under the graph

Area = (t 1-t 2) [ f (t1 )+ f (t 2)2 ]

For time (0.5-1.0) – (1.5-2.0) minutes

Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (1.0– 0.5)[ 0+0.0

2 ]= 0 g .min ¿m3


Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (2.5– 2.0)[ 0+1

2 ]= 0.25 g .min ¿m3


16

Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (3.0– 2.5)[ 1.0+2.3

2 ]= 0.825 g .min ¿m3


Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (3.5– 3.0)[ 2.3+2.6

2 ]= 1.225 g .min ¿m3


Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (4.0– 3.5)[ 2.6+2.6

2 ]= 1.3 g .min ¿m3


Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (4.5– 4.0)[ 2.6+2.6

2 ]= 1.3 g .min ¿m3

So the total area or ∫0

4

C ( t ) dt= ( 0.25 + 0.825 + 1.225 + 1.3)) = 4.9 g.min/m3

E ( t )= C( t)

∫0

∞

C (t )dtFor t = 0, C(t) = 0.0

E( t)=0 /4.9=0

For t = 0.5, C(t) = 0.0

E( t)=0 /4.9=0

For t = 1.0, C(t) = 0.0

E( t)=0 /4.9=0

17

For t = 1.5, C(t) = 0

E( t)=0 /4.9=0

For t = 2.0, C(t) = 0

E( t)=0 /4.9=0

For t = 2.5, C(t) = 1.0

E( t)=1.0/ 4.9=0.204

For t = 3.0, C(t) = 2.3

E( t)=2.3 /4.9=0.469

For t = 3.5,4.0,4.5 C(t) = 2.6

E( t)=2.6 /4.9=0.5306

Time(min) Conductivity Oulet E(t)

0.0 0.0 0.0

0.5 0.0 0.0

1.0 0.0 0.0

1.5 0.0 0.0

2.0 0.0 0.0

2.5 1.0 0.204

3.0 2.3 0.469

18

3.5 2.6 0.5306

4.0 2.6 0.5306

4.5 2.6 0.5306

Residence time distribution (RTD) function for plug flow reactor

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 50

0.1

0.2

0.3

0.4

0.5

0.6

Y-Values

Time (min)

E(t)

For time (0 – 0.5) – (1.5-2.0) = 0


Area = (t 2−t 1¿[ E(t 1+ t2)2 ] = (2.5 – 2)[ 0+0.204

2 ]= 0.051

For time (2.5 -3.0) minutes

Area = (t 2−t 1¿[ E (t1+t 2 )2 ] = (3– 2.5)[ 0.204+0.469

2 ]=0.16825

For time (3 -3.5) minutes

19

Area = (t 2−t 1¿[ E (t1+t 2 )2 ] = (3.5– 3)[ 0.469+0.5306

2 ]=0.2499

For time (3.4-4.0) & (4.0-4.5) minutes

Area = (t 2−t 1¿[ E (t1+t 2 )2 ] = (4.0-3.5)[ 0.5306+0.5306

2 ]=0.2653

∫0

∞

E ( t ) dt= Total area under the graph =

(0.2653+0.2653+0.2499+0.16825+0.051) =0.99975

Residence time ,tm=¿ ∫0

∞

tE ( t )dt= 4.5(0.99975)= 4.498875

Time(min) Oulet Conductivity (mS/cm)

E(t) tE(t) (t-tm)2E(t)dt

(t-tm)3E(t)dt

0.0 0.0 0.0 0.0 0.0 0.0

0.5 0.0 0.0 0.0 0.0 0.0

1.0 0.0 0.0 0.0 0.0 0.0

1.5 0.0 0.0 0.0 0.0 0.0

2.0 0.0 0.0 0.0 0.0 0.0

2.5 1.0 0.204 0.51 0.2038 -0.4073

3.0 2.3 0.469 1.407 0.378 -0.5666

3.5 2.6 0.5306 1.8571 0.2493 -0.249

4.0 2.6 0.5306 2.1224 0.066 -0.0652

4.5 2.6 0.5306 2.3877 0.00358 3.77 x 10-10

∑ 11.1 0.99975 8.2842 0.90068 -1.321

20

Mean residence time, tm=¿ ∫0

∞

tE ( t )dt=¿8.2842

Second moment, variance ,σ 2 = ∫0

∞

(t−tm)2 E(t) dt

= 0.90068

Third moment, skewness, s3= 1

σ32 ∫

0

∞

(t−tm)3E(t) dt

=1

(0.949)32 ¿-1.321) = -1.4289

8 DISCUSSION

Firstly, the objectives that need to be achieve for this tubular reactor experiment is to

examine the effect of a pulse input and step change in a tubular reactor and also to construct the

residence time distribution (RTD) function for the tubular flow reactor at the end of the

experiment. The experiment was run at the 700 mL/min of flow rate. While the experiment is

running, the conductivity for the inlet and outlet of the solution had been recorded at the period

of time where until the conductivity of the solution is constant. For a tubular reactor, the flow

that through the vessel is continuous, usually at the steady state and also configured thus the

conversion of the chemicals and other dependent variables are functions of position within the

reactor rather than of time.

For this experiment, we are examined the effects of flow for two types of reaction which

are in pulse input and step change. The flow rate of solution is kept constant at 700ml/min. For

these types of experiments, the graph of outlet conductivity versus times had been plotted. Based

on graph of pulse input, the outlet conductivity that had been plotted is 1.9 mS/cm at time of 1.5

minutes which are the highest value. After that, the conductivity decreases within the time and

comes to be constant at the time of 3 minutes. From the result, it showed that it results was not

21

differ from the theory that recorded that the conductivity is reaching zero at time of 4 minutes.

Thus, the experiment 1 is a success.

In addition, for the graph of step change the outlet conductivity is increase within the

time by started at time of 2.5 minutes which it inlet conductivity is 4.2 mS/min and then

undergoes some increment until at minutes 4.0 which the outlet conductivity is 2.6 mS/min.

There are differences between both of the graph where the outlet conductivity for step change is

increase smoothly compare to pulse input where the outlet conductivity is increase at the same

period of times and then it became decrease into the constant value.

Next experiment, to construct the residence time distribution (RTD) function for the

tubular flow reactor for pulse input and also step change. The residence time distribution is

plotted based on exit time (E(t)) versus time from the data that had been recorded in the table. From the graph,

it can be concluded that the residence time distribution is depends on the outlet conductivity.

9 CONCLUSION

From the experiment, we able to examine the effect of the pulse input and step change in

a tubular flow reactor and we also can differentiate both of the effect. Besides, we also able to

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

conductivity for inlet and outlet after 3 minutes for pulse input are both 0.00 mS/ while for the

step change is 4.2 mS/min and 2.3 mS/min respectively. The distribution of exit time, E(t) is

calculated for each 30 second until 4 minutes interval. The graphs for both pulse input and step

change experiments are plotted.

RECOMMENDATION

There are a few recommendations during conducting this experiment. First, all valves

should be properly placed before the experiment started. Secondly, the volume of sample

collected must be accurate throughout the experiment to avoid error during calculation. Next,

22

the flow rates should be constantly monitored so that it remains constant throughout the

experiment. Titration should be conducted carefully. It should be immediately stopped when

the indicator turned light pink. Titration should be repeat if the solution turns dark pink.

11 REFERENCES

Levenspiel O., “Chemical Reaction Engineering”, John Wiley (USA), 1972

Fogler H.S., “Elements of Chemical Reaction Engineering, 3rd Ed.”, Prentice Hall (USA), 1999

Astarita G., “Mass Transfer with Chemical Reaction”, Elsevier, 1967

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attachment_1428685327598_bp 101 b

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