Simulation Using PFR (Aspen Plus)

SIMULATION USING PLUG FLOW REACTOR 2013

ABSTRACT:

This laboratory is about the knowledge on how the simulation using the plug flow

reactor and it totally different and easier than the other tasks. In this lab 5, it is about the

comparison the result between the conversion with the different and varying length and

diameter of the plug flow reactor. Firstly, the plug flow is used in order to produce the

acetone from the reaction between ketene and methane. The flow rate of the feed that

enter into the reactor is 8000kg/hr of acetone. This reactor is assumed to be adiabatic with

the temperature is 1035K while the pressure is 1.6 atm. For the plug flow reactor, the state

of fluid package is different compare to the Peng-Robinson and SRK because it used

SYSOPO.

The objective is to calculate the conversion of the production by varying the length

and diameter of the tubes. For the starting, the length and diameter are assumed 3m and

1m respectively. Then, the result would come out and then we can calculate the conversion

of the production based on the molar flow of the components in the reactor.

INTRODUCTION:

In this experiment, the acetone was enter undergo a reaction to separate into two

components which are ketene and methane. The objective of this lab is known the

conversion of the acetone to produced ketene and methane with the different diameter and

length of the tubes. The feed that enter is 8000kg/hr thus what is the percentage conversion

at the end of the product??. By using this simulation, the entire question can be answer

easily.

OBJECTIVES:

1. To know the volume required for at least 20% conversion.

2. To know the percentage conversion of the product with the varying diameter and

length.


METHADOLOGY:

CH3COCH3 CH2CO + CH4

The reaction is first order with respect to acetone. The fed condition is 8000 kg/hr of

acetone to tubular reactor. The reactor is adiabatic, with inlet T is 1035K and the pressure is

1.6atm.

1. Use SYSOPO of state fluid package.(SI unit)

2. Reactor : ADIABATIC Length: Assume 3 m Diameter: Assume 1 m

3. Reaction type LHHW

4. Kinetic: Vapour, k: 1.125, To 1000 K, E = 67999 cal/mol5.

5. Driving force: Term 1Reactant: acetone exponent to 1Products: ketene and methane

exponent to 0.

6. Driving force: Term 2 All exponents and constant B, C, D = 0

Constant A = -10000007.

7. There length, diameter, number of tubes can be change to achieve specific goal

PROCEDURE:

1. Aspen plus V7.3.2 was started.

2. New, chemical processes and chemicals with metric unit were selected and click

created.

1. The components were defined in the components, specifications and selection tab.

For component name, ACETONE, KETENE and METHANE were entered.

2. Next, property method was defined by clicking on methods in the navigation pane.

SYSOPO Equation of State was selected as the base method.


3. After that, the flow sheet was constructed by clicked on simulation button at the

bottom left of the screen.

4. The equipment that is used in this laboratory was selected by clicked to the model

palette that have in the bottom of the screen.

5. The equipment that is only plug flow reactor.

6. The information that needed in the process such as flow rate, pressure, mole

fraction, temperature, driving force and reaction type of the equipment were

inserted in that equipment as in the question that provided in the lab manual.

7. The control panel was opened and the simulation was run.

APPARATUS:

List of equipment used in this process:

1. Plug flow reactor

PLUG

FEED

PRODUCT

FIGURE 1: PROCESS FLOW DIAGRAM

The process flow diagram above showed the equipment that had been used for the production of ketene and methane in the reactor. The process only used plug flow reactor. By setting up the data based on the specification stated, then the required information will be analysed and transformed into a data stream as in result.

Heat and Material Balance Table

Stream ID FEED OUT

From PFR

To PFR

Phase VAPOR VAPOR

Substream: MIXED

Mole Flow kmol/hr

ACETONE 137.7410 109.4326

KETENE 0.0 28.30835

METHANE 0.0 28.30835

Total Flow kmol/hr 137.7410 166.0493

Total Flow kg/hr 8000.000 8000.000

Total Flow l/min 1.21855E+5 1.29843E+5

Temperature K 1035.000 914.8328

Pressure atm 1.600000 1.600000

Vapor Frac 1.000000 1.000000

Liquid Frac 0.0 0.0

Solid Frac 0.0 0.0

Enthalpy cal/mol -29235.24 -24251.17

Enthalpy cal/gm -503.3612 -503.3612

Enthalpy cal/sec -1.1186E+6 -1.1186E+6

Entropy cal/mol-K -17.68577 -11.30441

Entropy cal/gm-K -.3045068 -.2346362

Density mol/cc 1.88395E-5 2.13141E-5

Density gm/cc 1.09420E-3 1.02688E-3

Average MW 58.08004 48.17846

Liq Vol 60F l/min 169.8718 190.3017


RESULT/WORK BOOK:

There result that had been analysed:

FIGURE 2: STREAM TABLES


QUESTIONS:

1. What volume required for at least 20% conversion?

2. Fill he conversion below if configuration of reactor is set as below:

DIAMETER LENGHT CONVERSION %

2 1 18.91

1 2 21.69

2 2 24.39

1.5 1 17.72

1.8 1 20.65

0.9 1 15.59

ANSWER:

1. The volume required at least 20% conversion:

The formula:

V = π D2

4 x L

At least 20% conversion, the specification od diameter and length as below:

Diameter, D= 2.65m

Length ,L = 1m

V = π (2.65)2

4 x 1

= 5.52 m3


2. The conversion of the following diameter and length:

a) Diameter, D = 2m ; Length, L = 1m

b) Diameter, D = 1m ; Length, L = 2m


Stream ID FEED PRODUCT

From PLUG

To PLUG

Phase VAPOR VAPOR

Substream: MIXED

Mole Flow kmol/hr

ACETO-01 137.7410 111.6962

KETEN-01 0.0 26.04479

METHA-01 0.0 26.04479


Total Flow kg/hr 8000.000 8000.000

Total Flow l/m in 1.21855E+5 1.29465E+5

Temperature C 761.8500 651.6236

Pressure bar 1.621200 1.621200

Vapor Frac 1.000000 1.000000

Liquid Frac 0.0 0.0

Solid Frac 0.0 0.0

Enthalpy cal/mol -29235.24 -24586.33

Enthalpy cal/gm -503.3612 -503.3612


Entropy cal/mol-K -17.68577 -11.66140

Entropy cal/gm -K -.3045068 -.2387463

Density mol/cc 1.88395E-5 2.10850E-5

Density gm /cc 1.09420E-3 1.02988E-3

Average MW 58.08004 48.84430

Liq Vol 60F l/m in 169.8718 188.6681


Heat an d Mater ial Balan ce Tab le

S tr eam I D FEED PROD UCT

Fr o m PLUG

To PLUGPh ase VA POR VA POR

Su b str eam: MI XED

Mo le F lo w k mo l/h r

ACETO- 0 1 1 3 7 .7 4 1 0 1 0 7 .8 5 4 2 KETEN- 0 1 0 .0 2 9 .8 8 6 7 5

METH A -0 1 0 .0 2 9 .8 8 6 7 5

To tal F lo w k mo l/h r 1 3 7 .7 4 1 0 1 6 7 .6 2 7 7

To tal F lo w k g /h r 8 0 0 0 .0 0 0 8 0 0 0 .0 0 0To tal F lo w l/min 1 .2 1 8 5 5 E+51 .3 0 0 7 9 E+5

Temp eratu r e C 7 6 1 .8 5 0 0 6 3 4 .7 1 2 8

Pr essu re b ar 1 .6 2 1 2 0 0 1 .6 2 1 2 0 0Vap o r Fr ac 1 .0 0 0 0 0 0 1 .0 0 0 0 0 0

Liq u id Fr ac 0 .0 0 .0

So lid Fr ac 0 .0 0 .0

En th alp y cal/mo l - 2 9 2 3 5 .2 4 - 2 4 0 2 2 .8 2En th alp y cal/g m - 5 0 3 .3 6 1 2 - 5 0 3 .3 6 1 2

En th alp y cal/sec - 1 .1 1 8 6 E+6- 1 .1 1 8 6 E+6

En tr o p y cal/mo l-K - 1 7 .6 8 5 7 7 - 1 1 .0 6 5 9 8

En tr o p y cal/g m- K - .3 0 4 5 0 6 8 - .2 3 1 8 7 0 6Den sity mo l/cc 1 .8 8 3 9 5 E- 52 .1 4 7 7 8 E- 5

Den sity g m/cc 1 .0 9 4 2 0 E- 31 .0 2 5 0 2 E- 3

Av er ag e MW 5 8 .0 8 0 0 4 4 7 .7 2 4 8 1

Liq Vo l 6 0 F l/min 1 6 9 .8 7 1 8 1 9 1 .4 4 0 9

c) Diameter, D = 2m ; Length, L = 2m

Heat and Material Balance T able

Stream ID FEE D PRODUCT

From PLUG

To PLUGPhase VAPOR VAPOR

Substream: MIXED

Mole Flow kmol/hr ACET O-01 137.7410 104.1527

KETE N-01 0.0 33.58827

MET HA-01 0.0 33.58827

Total Flow kmol/hr 137.7410 171.3292Total Flow kg/hr 8000. 000 8000.000


Temperature C 761.8500 618.2406Pressure bar 1.621200 1.621200

Vapor Frac 1.000000 1.000000

Liquid Frac 0.0 0.0

Sol id Frac 0.0 0.0Enthalpy cal/mol -29235. 24 -23503. 81

Enthalpy cal/gm -503.3612 -503.3612

Enthalpy cal/sec -1.1186E +6 -1.1186E +6Entropy cal/mol-K -17.68577 -10.53879

Entropy cal/gm-K -. 3045068 -.2257003

Density mol/cc 1. 88395E-5 2. 18747E-5

Density gm/cc 1. 09420E-3 1. 02141E-3Average MW 58.08004 46.69373

Liq Vol 60F l/min 169.8718 194.1122

d) Diameter, D = 1.5m ; Length, L = 1m

The conversion: ¿ x 100%

: |137.7410−171.3292137.7410 |

x100%

:24.39%


: |137.7410−167.6277137.7410 | x

100% : 21.69%


Hea t and Materia l Balanc e Ta ble

Strea m ID FEED P RODUCT

From P LUG

To P LUG

P hase VAP OR VAP OR

Substream : MIXED

Mole Flow kmol/hr

ACETO-01 137.7410 113.3266

KETEN-01 0.0 24.41431

METHA-01 0.0 24.41431


Total Flow kg/hr 8000.000 8000.000

Total Flow l/m in 1.21855E+ 5 1.29163E+ 5

Temperature C 761.8500 658.7451

P ressure ba r 1 .621200 1 .621200

Vapor Frac 1 .000000 1 .000000

Liquid Frac 0.0 0.0

Solid Fra c 0.0 0.0

Enthalpy ca l/mol -29235.24 -24833.54

Enthalpy ca l/gm -503.3612 -503.3612

Enthalpy ca l/sec -1.1186E+ 6 -1.1186E+ 6

Entropy ca l/mol-K -17.68577 -11.93004

Entropy ca l/gm -K -.3045068 -.2418148

Density mol/cc 1.88395E-5 2.09239E-5

Density gm /c c 1.09420E-3 1.03229E-3

Ave rage MW 58.08004 49.33543

Liq Vol 60F l/m in 169.8718 187.4914

e) Diameter, D = 1.8m ; Length, L = 1m


: |137.7410−162.1553137.7410 |X

100%

:17.72%



Stream ID FEED PRODUCT

From PLUG

To PLUG

Phase VAPOR VAPOR

Substream: MIXED

Mole Flow kmol/hr

ACETO-01 137.7410 112.2940

KETEN-01 0.0 25.44694

METHA-01 0.0 25.44694


Total Flow kg/hr 8000.000 8000.000


Temperature C 761.8500 654.2386

Pressure bar 1.621200 1.621200

Vapor Frac 1.000000 1.000000

Liquid Frac 0.0 0.0

Solid Frac 0.0 0.0

Enthalpy cal/mol -29235.24 -24676.40

Enthalpy cal/gm -503.3612 -503.3612


Entropy cal/mol-K -17.68577 -11.75876

Entropy cal/gm -K -.3045068 -.2398608

Density mol/cc 1.88395E-5 2.10256E-5

Density gm/cc 1.09420E-3 1.03074E-3

Average MW 58.08004 49.02324

Liq Vol 60F l/min 169.8718 188.2367

f) Diameter, D = 0.9m ; Length, L = 1m

Heat and Material Balance TableStream ID FEED PRODUCT

From PLUG

To PLUGPhase VAPOR VAPOR

Substream: MIXED

Mole Flow kmol/hr ACETO-01 137.7410 116.2728

KETEN-01 0.0 21.46816

METHA-01 0.0 21.46816Total Flow kmol/hr 137.7410 159.2091

Total Flow kg/hr 8000.000 8000.000

Total Flow l/m in 1.21855E+5 1.28556E+5Temperature C 761.8500 671.5321

Pressure bar 1.621200 1.621200

Vapor Frac 1.000000 1.000000Liquid Frac 0.0 0.0

Solid Frac 0.0 0.0

Enthalpy cal/mol -29235.24 -25293.09

Enthalpy cal/gm -503.3612 -503.3612Enthalpy cal/sec -1.1186E+6 -1.1186E+6

Entropy cal/mol-K -17.68577 -12.44138

Entropy cal/gm -K -.3045068 -.2475976Density mol/cc 1.88395E-5 2.06407E-5

Density gm /cc 1.09420E-3 1.03716E-3

Average MW 58.08004 50.24838Liq Vol 60F l/m in 169.8718 185.3652


: |137.7410−163.1879137.7410 |

X100%

:20.65 %


: |137.7410−159.2091137.7410 |

X100%

:15.59 %


THEORY:

CH3COCH3 CH2CO + CH4

The reaction is first order with respect to acetone. The fed condition is 8000 kg/hr of

acetone to tubular reactor. The reactor is adiabatic, with inlet T is 1035K and the pressure is

1.6atm.

1. Use SYSOPO of state fluid package.(SI unit)

2. Reactor : ADIABATIC Length: Assume 3 m Diameter: Assume 1 m

3. Reaction type LHHW

4. Kinetic: Vapour, k: 1.125, To 1000 K, E = 67999 cal/mol5.

5. Driving force: Term 1Reactant: acetone exponent to 1Products: ketene and methane

exponent to 0.

6. Driving force: Term 2 All exponents and constant B, C, D = 0

Constant A = -10000007.

7. There length, diameter, number of tubes can be change to achieve specific goal

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

http://en.wikipedia.org/wiki/Steady_state

http://en.wikipedia.org/wiki/Steady_state

http://en.wikipedia.org/wiki/Plug_flow_reactor_model


providing initially high driving forces, which diminish as the reactions progress down the tubes.

Flow in tubular reactors 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 inconveniently long reactors or may require unacceptably high feed rates.

The plug flow reactor model (PFR, sometimes called continuous tubular reactor, CTR, or piston flow reactors) is a model used to describe chemical reactions in continuous, flowing systems of cylindrical geometry. The PFR model is used to predict the behaviour of chemical reactors of such design, so that key reactor variables, such as the dimensions of the reactor, can be estimated.

Fluid going through a PFR may be modelled as flowing through the reactor as a series of infinitely thin coherent "plugs", each with a uniform composition, traveling in the axial direction of the reactor, with each plug having a different composition from the ones before and after it. The key assumption is that as a plug flows through a PFR, the fluid is perfectly mixed in the radial direction but not in the axial direction (forwards or backwards). Each plug of differential volume is considered as a separate entity, effectively an infinitesimally small reactor, limiting to zero volume. As it flows down the tubular PFR, the residence time (

) of the plug is a function of its position in the reactor. In the ideal PFR, the residence time distribution is therefore a Dirac delta function with a value equal to .

http://en.wikipedia.org/wiki/Dirac_delta_function

http://en.wikipedia.org/wiki/Residence_time

http://en.wikipedia.org/wiki/Perfect_mixing

http://en.wikipedia.org/wiki/Perfect_mixing

http://en.wikipedia.org/wiki/Chemical_reactor

http://en.wikipedia.org/wiki/Chemical_reaction

http://en.wikipedia.org/wiki/Turbulent

http://en.wikipedia.org/wiki/Laminar

Simulation Using PFR (Aspen Plus)

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