cre lab manuals
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NATIONAL INSTITUTE OF TECHNOLOGY, TIRUCHIRAPPALLI – 15
DEPARTMENT OF CHEMICAL ENGINEERING
CHEMICAL REACTION ENGINEERING LABORATORY MANUAL
ADIABATIC REACTOR
Aim: To study the effect of temperature on the rate of reaction between hydrogen peroxide and sodium thiosulphate under adiabatic reaction conditions and to determine the activation energy of the reaction.
Theory: The effect of temperature on the reaction mixture consisting of hydrogen peroxide and sodium thiosulphate when the reaction is carried out under adiabatic conditions, it can be observed and correlation with the reaction rate is given. As the exothermic reaction proceeds, the temperature increases and becomes constant. The rate of the reaction and temperature are correlated to various temperatures.
WhereTF – Final Temperature (°C)T0 – Initial Temperature (°C)K – Rate constantCA0 – Initial concentration (moles/ litre)
A graph is drawn between lnA Vs.1/T and the slope is equated to -E/R.
Procedure: Take 30 ml of hydrogen peroxide in a beaker and dilute it into 300 ml by using distilled water and pour it into the reactor, 300 ml of sodium thiosulphate solution will also be added in the reactor. Due to exothermic reaction, the temperature of reaction mixture starts increasing, the rise in temperature is noted at different time intervals as the reaction proceeds.
Tabulation:Time (sec)
Temperature (°C)
dT/dt (Ts – T)2 1/(T+273) (k-1)
A ln A
Model Graph:
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Model Calculation:1) t = 2) T =
3)
4) (Tf – T)2
5)
6) lnA =
7) =
8) Slope= -E/R9) E=
Result and Inferences:
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BATCH REACTOR -1
Department of Chemical Engineering
Slope = -E/R
1/T (k-1) x0
lnA
T°C
Time (s)
2
Aim: To verify the order and to determine the rate constants for the reaction between equimolar quantity of NaOH and ethyl acetate in a batch reactor.
Reaction:NaOH + CH3COOC2H5 CH3COONa + C2H5OH
Theory: For a second order reaction, the rate of reaction is as follows
Integrating,
Procedure: 50 ml of NaOH and 50 ml of ethyl acetate are taken in the batch reactor with the starting and stop water. Then each 10 ml of the reaction mixture is taken every 5 minutes the reaction is arrested by adding acetic acid to the sample. The reaction mixture is titrated against sodium hydroxide of known normality and its concentration found. Samples are taken up to 50 minutes and the concentration of the reactor is found.
Standard Data:Normality of NaOH :Normality of Acitic Acid:Normality of Ethyl acetate:
Tabulation:
S.No. Reaction Time (min)
Volume of CH3COOH(ml)
Volume of NaOH (ml)
CA
(mol/lit)1/CA
(lit/mol)XA
1 52 103 154 205 256 307 358 409 4510 50
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Model Graph:
Model Calculation:
1)
2)
3)
4)
5)
Result: Thus the experiment on batch reactor was performed. The order of the reaction was verified and the value of K found from graph.
K=-----------------------(1/CA vs time graph)K=-----------------------(XA/(1-XA) vs time graph)
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BATCH REACTOR – IIAim: To verify the order and to determine the rate constants for the reaction between non- equimolar quantity of NaOH and ethyl acetate in a batch reactor.
Department of Chemical Engineering
t
kAC1
0AC1
0x
tx
0
kCA0
yy
A
A
X-1
X
4
Reaction:NaOH + CH3COOC2H5 CH3COONa + C2H5OH
Theory: In a batch reactor, the composition of the components is uniform throughout at any instant of time
Procedure: 200 ml of NaOH and 400 ml of ethyl acetate of known concentration are taken in the reactor. Samples (10ml) are drawn for every 5 minutes from the reactor up to 50 minutes. The concentration of reactants in the sample is found out by adding 10 ml of acetic acid and titrating against sodium hydroxide.
Standard Data:Normality of NaOH :Normality of Acitic Acid:Normality of Ethyl acetate:
Tabulation:S.No. Reaction
Time (min)
Volume of CH3COOH (ml)
Volume of NaOH (ml)
CA
(mol/lit) XA M
1 52 103 154 205 256 307 358 409 4510 50
Model Graph:
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Model Calculation:
1)
2)
3)
4)
5)
6)
Result: Thus the experiment on batch reactor – II was performed. The order of the reaction was verified and the value of k found the graph is
K =
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Department of Chemical Engineering
Time (min)x
0
Slope = K (CB0 – CA0)
y
A
A
X1M
XMln
6
MIXED FLOW REACTOR
Aim: To study the performance of a mixed flow reactor using second order saponification reaction.
Reaction: NaOH + CH3COOC2H5 → CH3COONa + C2H5OHTheory:
In a mixed flow reactor, properties of the reaction mixture are uniform. Thus for example, concentration of the reactants at inlet of the second order reaction and outlet concentration of the reactants remain the same. The design equation for reaction
CA0 = CB0, CA = CB,
Experimental Setup:It consists of a 500ml flask with a flow steam. This is attached with the flow meter for
setting the flow rate.
Procedure: The residence time of the reactor is adjusted by adjusting of reactants the flow rate
and keeping the reactor volume constant. When steady state is reached a sample is collected. Excess acetic acid is added to the sample in order to arrest the reaction. Thus moles of unreacted reactants and hence the conversion can be found.
Standard Data:Normality of NaOH :Normality of Acitic Acid:Normality of Ethyl acetate: Flow rate of NaOH =Flow rate of Ethylacetate =
TabulationS.No Sample
Volume (ml)Burette Reading(ml) Volume of NaOH
consumed (ml)Initial Final
Model Calculation:
1.
2.
3.
4.
Result: Thus the experiment of mixed flow reactor is studied and the conversion is found to be:
Theoretically (XAtheo): Experimentally (XAexp):
**********MIXED FLOW REACTOR IN SERIES
Department of Chemical Engineering 7
kCA0
Aim: To study the performance of a mixed flow reactor in series, using second order saponification.
Reaction: NaOH + CH3COOC2H5 → CH3COONa + C2H5OH
− rA = KCACB = KCA2
Theory: In a mixed flow reactor, properties of the reaction mixture are uniform. Thus we have
the equimolar concentration of reactant at inlet for the second order reaction. The outlet concentration will hence be the same.CA0 = CB0, CA = CB,
Procedure: The residence time of the reactor is adjusted by setting the flow rate of reactants and
keeping the reactor volume constant. When steady state is reached a sample is collected and excess acetic acid is used to arrest the reaction. Thus moles of unreacted reactants and the conversion can be found.
Standard Data:Normality of NaOH :Normality of Acitic Acid:Normality of Ethyl acetate: Flow rate of NaOH =Flow rate of Ethylacetate =
TabulationFor Reactor-IS.No Sample
Volume (ml)Burette Reading(ml) Volume of NaOH
consumed (ml)Initial Final
For Reactor-IIS.No Sample
Volume (ml)Burette Reading(ml) Volume of NaOH
consumed (ml)Initial Final
Model Calculation:
At steady state in Reactor I
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At steady state in Reactor II
Theoretical conversion:
Reactor I:
Reactor II:
Result: Thus the experiment of mixed flow reactor in series is studied and the conversion is
found to be:For Reactor-I Theoretically : Experimentally:For Reactor-I Theoretically : Experimentally:
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PLUG FLOW REACTOR
Aim:To study the performance of the plug flow reactor for the second order reaction of
saponification of ethyl acetate.
Reaction:NaOH + CH3COOC2H5 → CH3COONa + C2H5OH
Experimental setup:It consists of a transparent tube provided with glass beads ( = 0.04) sampling can be
done at different points all along the length of the tube.
Procedure: NaOH and CH3COOC2H5 solution of equal flow rate is allowed to enter at a constant flow rate until steady state is reached. When the inlet flow rate equals the outlet flow rate, the steady state is said to be attained. Samples are collected at different position, acetic acid is added to arrest the reaction. The concentration of unreacted NaOH and conversion in the mixture is noted.
Standard Data:Normality of NaOH :Normality of Acitic Acid:Normality of Ethyl acetate: Flow rate of NaOH =Flow rate of Ethylacetate =
Tabulation:S.No Sample
Volume (ml)Burette Reading(ml) Volume of NaOH
consumed (ml)Initial Final
S.No Reactor volume (ml)
Space time (min)
Titrant volume (ml)
CA (N) XA (%)(expt.)
XA (%)(theo)
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Model Graph:
Model Calculation:1. CAo= NNaOH/2
2.
3.
4.
5.
Result: Thus the performance of plug flow reactor under constant flow rate is studied and necessary graphs are drawn.
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Department of Chemical Engineering
Theoretical
Experimental
XA
x0
y
Time(min)
11
RTD STUDIES IN A PLUG FLOW REACTOR
Aim: To study the behavior of a plug flow reactor by RTD studies.
Theory: Elements of fluid taking different routes through the reactor may take different lengths of time to pass through the vessel. The distribution of these times for the stream of fluid leaving the vessel is called the exit age distribution E, or the residence time distribution (RTD) of the fluid. From E mean residence time, flow pattern, model parameters can be evaluated.
Procedure: In a plug flow reactor, a tube packed with particles is used. To start with reactor is filled with 0.05N of NaOH Water flow is allowed from a water tank above the reactor. The variation of concentration of sodium hydroxide in the each taping point is noted. The dispersion number is obtained from the graph.
Formulae:1) 2)
3)
where,
∆ti = time interval
Standard data:Normality of NaOHNormality of Acitic Acid;Flow rate of water
Tabulation:Time (min)
VNaOH
(ml)VCH3COOH
(ml)NNaOH Eiti Eiti
2
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Model Graph:
Model Calculation:
1.
2. F=N/Nmax. =
3.
4. 5.
6.
7.
8.
Result: Thus, the experiment of plug flow RTD was conducted and the dispersion number and N were calculated.
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Department of Chemical Engineering
F E
y y
x xt t
13
RTD STUDIES IN MIXED FLOW REACTOR
Aim: To study the behavior of the mixed flow reactor through RTD studies.
Theory: Elements of fluid taking different routes through the reactor may take different lengths of time to pass through the vessel. The distribution of these times for the stream of fluid leaving the vessel is called the exit age distribution E, or the residence time distribution (RTD) of the fluid. From E mean residence time, flow pattern, model parameters can be evaluated.
Experimental setup and procedure: Reactor consists of 500 ml beaker attached with stirrer. The flow of water is allowed from a bottle packed above the level of the reactor. The concentration of NaOH in the exit stream is determined in the samples collected at intervals the graphs are hence obtained.
Standard data:Normality of NaOHNormality of Acitic Acid;Flow rate of water
Tabulation:Time (min)
VNaOH
(ml)VCH3COOH
(ml)NNaOH Eiti Eiti
2
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Model Graph:
Model Calculation:
1.
2. F=N/Nmax. =
3.
4. 5.
6.
7.
8.
Result: Thus, the experiment of mixed flow RTD was conducted and the dispersion number and N were calculated.
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Department of Chemical Engineering
F C
y y
x xt t
x’ x’
y’y’
15
SEGREGATED FLOW REACTOR
Aim: To calculate the performance of a tubular reactor as a segregated flow reactor for the saponification of ethanol.
Reaction:NaOH + CH3COOC2H5 → CH3COONa + C2H5OH
Theory: In laminar flow in a tubular reactor, segregated flow occurs. The conversion is time dependant as the element moves through the water. The conversion in each element of fluid depends upon the residence time. Hence, to obtain average uniform conversion model equation incorporating non – ideal flow is used.
Procedure:NaOH and ethyl alcohol at known concentrations are allowed to enter at a flow rate of
60 cc/min each into the reactors. Sufficient time is allowed to reach steady state. Samples are collected drop by drop at different points. Concentration is found by the addition of acetic acid and titration with NaOH.
From the volume and concentration of sample with NaOH, its concentration is found out.
Formulae:
1)
2)
3)
4)
Standard Data:Normality of NaOH :Normality of Acitic Acid:Normality of Ethyl acetate: Flow rate of NaOH =Flow rate of Ethylacetate =
Tabulation:S.No Sample
Volume (ml)Burette Reading(ml) Volume of NaOH
consumed (ml)Initial Final
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S.No Reactor volume (ml)
Space time (min)
Titrant volume (ml)
CA(mol/lit) XA(Plug) XA (Seg) XA(exp)
Model Calculation:1. CAo= NNaOH/2
2.
3.
4.
5.
6.
Model Graph:
Result: Experiments were conducted in segregated flow and the conversions at various times were calculated and graphs of conversion Vs time were drawn.
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Department of Chemical Engineering
XAP
XA
x0
y
Time (min)
XAS
XAe
17