cre lab manuals

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:

Department of Chemical Engineering 1

Model Calculation:1) t = 2) T =

3)

4) (Tf – T)2

5)

6) lnA =

7) =

8) Slope= -E/R9) E=

Result and Inferences:

--------------

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


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)

**********

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.


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:


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 =

**********


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


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.


TabulationFor Reactor-IS.No Sample



For Reactor-IIS.No Sample



Model Calculation:

At steady state in Reactor I


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:

**********


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.


Tabulation:S.No Sample



S.No Reactor volume (ml)

Space time (min)

Titrant volume (ml)

CA (N) XA (%)(expt.)

XA (%)(theo)


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.

**********


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


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.

**********


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


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.

**********


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)


Tabulation:S.No Sample




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.

**********


XAP

XA

x0

y

Time (min)

XAS

XAe

17

cre lab manuals

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initial finalmodel

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plug flow

naoh flow