batchreactor simulation-3

8/7/2019 BatchReactor Simulation-3

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TEACHING THE SIMULATION PROCESS IN

AN UNDERGRADUATE CHEMICALREACTORS DESIGN COURSE

I.P

.N.

Enrique Arce Medina

Escuela Superior de Ingeniera Qumica e industrias Extractivas

INSTITUTO POLITECNICO NACIONAL

MEXICO


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1. Objectives

1. Objectives

AGENDA

AGENDA

2. Introduction

2. Introduction

6. Conclusion

6. Conclusion

4. The modeling task

4. The modeling task

3. Statement of the problem

3. Statement of the problem

5. Results

5. Results


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Objectives

By the end of the simulation project students should

understand the concepts of analysis and design of chemical

reactors.

Students should acquire basic skills that demand performanceof task sequences like enriching the model of a reactor in

steps by proposing and validating the structure and

parameters of the model and running the simulation.


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Introduction

The course includes:

Calculations of mass and energy balances in reactors

Curve fitting of kinetics parameters and

Reactor design.

Students are required to participate in the solution of real

problems as small projects

The illustrated problem presented in this paper stressed

the unsteady state dynamics of a batch chemical reactor.


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Statement of the Problem

It is required to develop a model and simulate the process ofhydrogenation of fatty oils.

Reactor

Steam

Hydrogenbubbles

Oil input

Hydrogen

tank

Oil output

Preheatingof oil is done

first with

steamHydrogen is

dispersed into the

oil by means of asparger

gas is withdrawn from

the reactor vessel,

purified, and recycled

to the sparger together

with fresh gas.


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0.306.76-0.4Linolenic (C18:3)

63.5050.8030.658.3Linoleic (C18:2)

20.7022.8050.318.1Oleic (C18:1 )

4.113.873.22.24Estearic (C18:0 )

SunflowerSoybeanPeanutCottonseedFatty acids

Fatty acid composition, weight percent

In the process the double bonds of the fatty acid chains aresaturated with hydrogen, in order to reduce levels of linolenic

acid in fatty oils thus eliminating problems of bad flavors and

poor stability

aci dteari cci dl ei cci di nol ei cci di nol eni c 3k2k2k2 +++


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The modeling task

Energy balance equations of different phases of the processare derived, then the model parameters are tuned to give a

minimum error between the process and the model responses

1. Preheating the

unsaturated oil while it is

loaded to the reactor

2. Heating of the reactor

contents to attain the

initiation temperature

3. Hydrogenation reactions

4. Cooling of the products


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Stage 1:Preheating of the unsaturated oil

)()(11 bmbi

b TTUATTWCpdt

dTCpV +=

W = the flow rate of oil,

Cp = average heat capacity of oil, = density of oil,

A1 = heat exchange area of the preheater,

V = reactor volume,

U1 = heat transfer coefficient of the preheater,Tb = oil temperature leaving the preheater

Ti = oil temperature entering the preheater

Tm = steam temperature.

t = time

This is an

unknown

parameter


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Data from the plant concerning the preheating phase is related

to the mean duration time for the batch heating, whichcorresponds to 46 minutes and a final temperature of the oil

around 212 F.

The equation obtained is:

)0.356(11.1)0.77(507.0 bb TTdt

dT+=


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Stage 2: The heating of the oil

)356(645.0 11

b

b

Tdt

dT=


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Stage 3: The hydrogenation of the oil

Ck-=dt

dC=r A1

AA

Ck-Ck=dt

dC=r B2A1

BB

Ck-Ck=dt

dC=r C3B2

CC

Ck=dt

dC=r C3

DD

CA = concentration of the linolenic acid

CB = concentration of the linoleic acid

CC= concentration of the oleic acid

CD = concentration of the stearic acid

A

TECek

/

111=

B

TE

Cek

/

22

2=

C

TECek

/

333=


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The energy balance in the reactor

))(( iodiderDCBA IH

CpV

rrrr

dt

dT

+++=

V = Volume of reactor,-Hr = heat of reaction,

Iiodide = iodide index reduced per minute

= mixture density,

Cp = average soybean oil heat capacity.

The iodide index is determined as a function of acids concentration in the soybean oil

348.50

87.8904.18152.273 CBAIodide

CCCI

++=

Hydrogenation is considered terminated when the iodide index reaches the value of 110


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Stage 4: The cooling of the mass products

[ ]162/)140(ln)226(583.1

3

33

=

b

bb

T

T

dt

dT


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Results

0

50

100

150

200

250

300

350

400

0 25 50 75 100 125 150 175

Time, min

T(F)

(a) (b) (c) (d)

Temperature evolution in the reactor


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Results

0

10

20

30

40

50

60

0 10 20 30 40 50

Time (min)

Mole%

linolenic

linoleic

oleic

stearic

Concentration profiles of fatty acids


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Thank you very much

batchreactor simulation-3

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