Tubular Aku

7/28/2019 Tubular Aku

1/17

ABSTRACT

From this experiment, our objectives are to examine the effect of pulse input in a tubular flow

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

First of all, the equipment is set up before we can run the experiment. After that, we set up theflowrate that is 700mL/min. After the conductivity for inlet and outlet we collected are reaching

to a constant value, the experiment is stopped. The conductivity for inlet and outlet after 5

minutes are 0.0mS/cm and 0.0mS/cm. The outlet conductivity, C( t) then is calculated and the

value we get is 3.25. Then, we are able to determine the distribution of exit time, E( t). The E(t) is

calculated for each 30 seconds until it reach 2 minutes interval. The sum of E( t) we get is 1.00

which is the residence time distribution. Graphs for outlet conductivity, C(t) against time and

distribution of exit time, E(t) against time is plotted. The graphs we get from this experiment are

just the same with the graphs in the theory. The value of E(t) is depends on the value of C(t).


2/17

INTRODUCTION

In the tubular reactor, the reactants are continually consumed as they flow down the length of the

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

and greatly deviate from ideal plug-flow behaviour, 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 conveniently long reactors or may require unacceptable high feed rates.

However, many tubular reactors that are used to carry out a reaction do not fully conform to this

idealized flow concept. 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. The nature of the tracer peak gives an indication of the non-ideal that would be

characteristic of the reactor.

For most chemical reactions, it is impossible for the reaction to proceed to 100% completion.

The rate of reaction decreases as the percent completion increases until the point where the

system reaches dynamic equilibrium (no net reaction, or change in chemical species occurs). The

equilibrium point for most systems is less than 100% complete. For this reason a separation

process, such as distillation, often follows a chemical reactor in order to separate any remaining

reagents or by products from the desired product. These reagents may sometimes be reused at the

beginning of the process, such as in theHaber process.

Tubular flow reactors are usually used for this application which are:

1. Large scale reactions

2. Fast reactions

3. Homogeneous or heterogeneous reactions

4. Continuous production
http://en.wikipedia.org/wiki/Distillationhttp://en.wikipedia.org/wiki/Haber_processhttp://en.wikipedia.org/wiki/Haber_processhttp://en.wikipedia.org/wiki/Haber_processhttp://en.wikipedia.org/wiki/Distillation


3/17

5. 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. It can also be very useful in modelling reactor

behaviour and in the estimation of effluent properties. This technique is, thus, also extremely

important in teaching reaction engineering, in particular when the non-ideal reactors become the

issue. The work involves determining RTDs, both by impulse and step tracer injection

techniques, and applying them to the modelling of the reactor flow and to the estimation of the

behaviour of a nonlinear chemical transformation. The RTD technique has also been used for the

experimental characterization of flow pattern of a packed bed and a tubular reactor that exhibit,

respectively, axially dispersed plug flow and laminar flow patterns (FEUP).

The concept of using a tracer species to measure the mixing characteristics is not limited to

chemical reactors. In the area of pharmacokinetics, the time course of renal excretion of species

originating from intravenous injections in many ways resembles the input of a pulse of tracer

into a chemical reactor. Normally, a radioactive labelled (2H, 14C, 32P, etc.) version of a drug is

used to follow the pharmacokinetics of the drug in animals and human.

Another important field of RTD applications lies in the prediction of the real reactor

performance, since the known project equations for ideal reactor are no longer valid. Now the

concepts of macro and micro mixing are fundamental. For each macro mixing level, expressed in

the form of a specific RTD, there is a given micro mixing level, which lies between two limiting

cases, complete segregation and perfect micro mixing.


4/17

OBJECTIVES

The objectives of this experiment are:

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

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

THEORY

In a tubular flow reactor, the feed enters at one end of a cylindrical tube and the product stream

leaves at the other end. The long tube and the lack of provision for stirring prevent complete

mixing of the fluid in the tube. Hence the properties of the flowing stream will vary from one

point to another, namely in both radial and axial directions. It is often not necessary to know

details of the entire flow fluid but rather only how long fluid elements reside in the reactor (i.e.

the distribution of residence times). This information can be used as a diagnostic tool to ascertain

flow characteristics of a particular reactor.

The age of a fluid element is defined as the time it has resided within the reactor. The concept

of a fluid element being a small volume relative to the size of the reactor yet sufficiently large to

exhibit continuous properties such as density and concentration was first put forth by

Danckwerts in 1953.

In order to analyze the residence time distribution of the fluid in a reactor the following

relationships have been developed. Fluid elements may require differing lengths of time to travel

through the reactor. The distribution of the exit times, defined as the E( t) curve, is the RTD of

the fluid. The outlet conductivity of a tracer species C(t) can be used to define E(t). That is:


5/17

Based on the data collected, a graph of conductivity versus time could be draw to obtain the C(t)

curve and data of the integral C(t) could be calculate.

Figure 1: Theory of graph with its formula area under the graph

If the RTD function, E(t), is very broad, however, it may be difficult to inject an amount of tracer

that is sufficiently large so as to keep the outlet concentration sufficiently high to be measured

accurately.


6/17

Figure 2: Example of graph when distribution exit time is very abroad


7/17

APPARATUS

1. Soltec Tubular Flow Reactor instrument

2. Clock watch

3. Solution 0.025M Sodium Chloride and De-ionized water.

Figure 3: Soltec Tubular Flow Reactorinstrument


8/17

EXPERIMENTAL PROCEDURES

General Start-Ups

1. All valves are initially closed except valves V7.

2. 20Liters of salt solution is prepared

3. Feed tank B2 is filled with the sodium chloride solution.

4. The ON power button is turn.

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

and the feed tank B1 is allowed to feed with the water. Valve V3 is closed as the water

level reached the tank mark.

6. Valve V2 and V10 is opened and pump P1 is switched on. From observing the flow

meter F1-01 value, The P1 pump is adjusted by controlling the flow controller to obtain a

flow rate of approximately 700mL/min.

7. V6 and V12 are opened and pump 2 P2 is switched on. From observing the flow meter

F1-02 value, The P2 pump is adjusted by controlling the flow controller to obtain a flow

rate of approximately 700mL/min. Then the valve V12 is closed and pump P2 is turn off.

8. The experiment can now be carried out.

Experiment 1:0.0486 Pulse input in a Tubular Flow Reactor.

1. Valve V9 is opened and pump P1 is switched on.

2. The P1 pump is adjusted by controlling the flow controller to obtain a flow rate of

approximately 700mL/min of de-ionized water into the reactor R1.

3. The de-ionized water is allowed to continue flowing through the reactor until the inlet

(Q1-01) and outlet (Q1-02) conductivity values are stable at low levels. Both

conductivity values is recorded.

4. Valve V9 is closed and pump P1 is switched off.

5. Valve V11 is opened and pump P2 is switched on. The timer is simultaneously started.

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

reactor R1 at 700mL/min at F1-02.


9/17

7. The salt solution is allowed to flow for 1minute, the timer is reset and restarted. This will

start the time at the average pulse input.

8. Valve V11 is closed and pump P2 is switched off. Valve V9 is quickly opened and pump

P1 is switch on.

9. By adjusting pump P1 flow controller, the de-ionized water flow rate is always

maintained at 700mL/min.

10. The inlet (Q1-01) and outlet (Q1-02) conductivity values are recorded at regular interval

of 30 seconds.

11. The conductivity values are recorded until all readings are almost constant and approach

stable low level values.


10/17

RESULTS

Experiment 1: Pulse Input in a Turbular Flow Reactor

Flow rate = 700 mL/min

Input type = De-ionized Water

Time(min)

Conductivity (mS/cm) C(t) E(t)

Inlet Outlet Cit Ci(t)Ci(t)

0.0 0.0 2.5 1.25 0.3846

0.5 0.0 2.4 1.20 0.36921.0 0.0 1.4 0.70 0.2154

1.5 0.0 0.2 0.10 0.0308

2.0 0.0 0.0 0.00 0.0000

Table 1

Graph 1: outlet conductivity against time


11/17

Graph 2: distribution of exit time, E(t) against time

Experiment 2: Step Change Input in a Turbular Flow Reactor

Flow rate = 700 mL/min

Input type = De-ionized Water

Time

(min)

Conductivity (mS/cm) C(t) E(t)

Inlet Outlet Cit Ci(t)Ci(t)

0.0 3.1 0.0 0.00 0.0000

0.5 3.2 0.0 0.00 0.0000

1.0 3.3 1.3 0.65 0.1024

1.5 3.3 1.6 0.80 0.1260

2.0 3.3 1.9 0.95 0.1496

2.5 3.3 1.9 0.95 0.1496

3.0 3.3 2.0 1.00 0.1575

3.5 3.3 2.0 1.00 0.1575

4.0 3.3 2.0 1.00 0.1575


12/17

Graph 3: outlet conductivity against time

Graph 4: distribution of exit time, E(t) against time


13/17

SAMPLE OF CALCULATION

Area =(2.4x0.5)+(2.5x0.5)+(1.4x0.5)+(0.2x0.5)+(0x0.5)

Area = 3.25

DISCUSSIONS

By doing this experiment, we are able to examine the effect of pulse input in a tubular flow

reactor. At the end of the experiment, we are also able toconstruct a residence time distribution

(RTD) function for the tubular flow reactor. The experiment was run at flowrate of 700mL/min.

The conductivity for the inlet and outlet was recorded from time equal to t 0=0 until them both

reaching a constant value for itself. In the end, the conductivity we get for the inlet is 0.0mS/cm

and meanwhile for the outlet conductivity is 0.0mS/cm.

The age of a fluid element is defined as the time it has resided within the reactor. The concept

of a fluid element being a small volume relative to the size of the reactor yet sufficiently large to

exhibit continuous properties such as density and concentration. Fluid elements may require

differing lengths of time to travel through the reactor. The distribution of the exit times, defined

as the E(t) curve, is the RTD of the fluid. The outlet conductivity of a tracer species C( t) can be

used to define E(t). The value of E(t) is calculated for every single of time that is for each

30seconds until reached 2 minutes where the outlet conductivity reach to its constant value. The

residence time distribution we get in the end is 1.00minutes.

From the result obtain, there are 2 graphs that needed to be plot. They are graph of outlet

conductivity, C(t) against time and graph of distribution of exit times, E(t) against time. From the

graph we get, they are just the same with the graphs that are in the theory. The distribution of

exit time is depends on the outlet conductivity. In the same time, it shows that residence time

distribution is depends on the outlet conductivity.


14/17

CONCLUSIONS

From this experiment, we are able to examine the effect of pulse input in a tubular flow reactor

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

conductivity for inlet and outlet after 2 minutes are 0.0mS/cm and 0.0mS/cm. The outlet

conductivity, C(t) is then calculated and the value we get is 3.25. The distribution of exit time,

E(t) is calculated for each 30 seconds until it reach 5 minutes interval Graphs for outlet

conductivity, C(t) against time and distribution of exit time, E(t) against time is plotted. The

graphs we get from this experiment are just the same with the graphs in the theory. The value of

E(t) is depends on the value of C(t). This experiment was a success.

RECOMMENDATIONS

There are several recommendations that can be taken in order to get more accurate result that are:

1. The flowrate of fluid in the reactor must constant all the time during the experiment. This

is because the flow rate is always reset when we switch on and off the pump.

2. All the flow valves need to be examine and testing need to be done before the experiment

is carried out so that all the data needed for the experiment can be obtained.

3. Make sure that only one person doing the reading. This is due to the fluctuation of the

inlet and outlet conductivity reading panel.

4. Make sure that certain valve need to be open and closed rapidly, so one person must

handle this valve with efficiently to get more accurate reading.

5. And also make sure in the storage tank is always with a solution and not it will be empty.

It will cause error the whole experiment when it carried out.


15/17

6.

REFERENCES

1. Fogler, H.S (2006). Elements of Chemical Reaction Engineering, 4 th Edition, New

Jersey:Prentice Hall

2. Schmidt, L.D. (2005), The Engineering of Chemical Reactions, 2nd Edition, Oxford

University Press, New York . Chapter 8.3.2.

3. P.V. Danckwerts, (1958) The effect of incomplete mixing on homogeneous reactions,

Chem. Eng. Sci., 8, pp. 93-99

4. www.ijee.dit.ie/articles/Vol18-6/IJEE1328.pdfat 5.60pm 19 Feb 2011

5. http://caltechbook.library.caltech.edu/274/9/FundChemReaxEngCh8.pdf at 8.10pm at 19

Feb 2011

6. http://www.ugrad.math.ubc.ca/coursedoc/math101/notes/moreApps/moments.html at

1.00am 24 Feb 2011
http://www.ijee.dit.ie/articles/Vol18-6/IJEE1328.pdfhttp://caltechbook.library.caltech.edu/274/9/FundChemReaxEngCh8.pdfhttp://www.ugrad.math.ubc.ca/coursedoc/math101/notes/moreApps/moments.htmlhttp://www.ijee.dit.ie/articles/Vol18-6/IJEE1328.pdfhttp://caltechbook.library.caltech.edu/274/9/FundChemReaxEngCh8.pdfhttp://www.ugrad.math.ubc.ca/coursedoc/math101/notes/moreApps/moments.html


16/17

UNIVERSITI TEKNOLOGI MARAFAKULTI KEJURUTERAAN KIMIA

CHEMICAL ENGINEERING LABORATORY III(CHE574)

No. TitleAllocated Marks(%)

Marks

1 Abstract/Summary 5

2 Introduction 5

3 Aims 5

4 Theory 55 Apparatus 5

6 Methodology/Procedure 10

7 Results 10

8 Calculations 10

9 Discussion 20

10 Conclusion 10

11 Recommendations 5

12 Reference / Appendix 10

TOTAL MARKS 100

Remarks:

Checked by :

---------------------------Date :

NAME : MUHAMAD AIMAN BIN HASSAN

STUDENT NO. : 2012266886

GROUP : GROUP6

EXPERIMENT : TUBULAR BATCH REACTOR (L3)

DATE PERFORMED : 23 MAY 2013

SEMESTER : 4

PROGRAMME / CODE : EH 220

SUBMITTED TO : MDM NORASMAH MOHAMMED


17/17

Tubular Aku

Documents

Transcript of Tubular Aku