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Pam Kubinski, Bethany Schmid,

Joe Haupt

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Project Specifications

Background

Reactor Designs

Results

Optimization

Comparison

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Formation of Maleic anhydride from n-butane Fixed bed reactor design

40,000 Mtons/yr

Reactor Designs Single reaction kinetics

Isothermal, isobaric

Isothermal including pressure drop

Kinetics from literature

Multiple Reactions-isothermal

Multiple Reactions-including energy balance

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Produced from oxidation of:

N-butane

Benzene

N-butene

Used in manufacture of

Resins Lubricant Additives

Surface Coatings Plasticizers

Maleic Anhydride

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http://www.huntsman.com/performance_products/eng/Home/Maleic_Anhydride/Maleic_Anhydride/index.cfm?PageID=5727

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Reaction and KineticsC4H10 + 3.5 O2 C4H2O3 + 4H20

Inlet Conditions

220 kPa 1.7 mol % Butane

400 C

Added Constraints

80% Conversion No side reactions

Bulk Density 900 kg/m3

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As inlet temperature increases conversionof butane increases

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0 20000 40000 60000

C

sooBa

Catalyst Weight (kg)

450

425

400

375

350

Conversion Profiles for Various Isotherms

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Additional Constraints

Used Ergun Equation

Evaluated

5 mm particles

7 mm Particles

= 0.44

www.andinst.com/dairy-pressure-products.php

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Solid lines- isobaric

Dotted lines- including pressure drop

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 10 20 30 40 50 60 70

N

aC

so

Reactor Volume (m3)

Effect of Temperature on n-Butane Conversion300 C

325 C

350 C

375 C

400 C

425

450

475 C

300 C

325 C

350 C

375 C

400 C

425 C

450 C

475 C

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Held reactor volume constant Varied tube diameter

0

5

10

15

20

25

6.2 6.6 7 7.4

PcPeueDo

Reactor Diameter

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Held reactor volume constant

Varied reactor length

0

10

20

30

40

50

60

70

80

90

100

0 1 2 3 4 5 6 7

PeueDo%

Length (m)

0.005m Dp

0.010m Dp

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C4H10 + 3.5 O2 C4H2O3 + 4H2O

C4H2O3 + O2 4CO + CO2 + H2O

C4H10 + 5.5O2 2CO + 2CO2 + 5H2O

Butane + Oxygen

CO, CO2, H2O

Total Oxidation Products

Maleic Anhydride + Water

Desired

Reaction

Decomposition

Reaction

Total Oxidation

Reaction

1

23

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Flows excluding inert

0

0.01

0.02

0.03

0.04

0.05

0.06

0 100000 200000 300000 400000 500000

MoaCmpto

Catalyst Weight (kg)

nButane

Maleic Anhydride

Water

Carbon Dioxide

Carbon Monoxide

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0.3

0.31

0.32

0.33

0.34

0.35

0.36

0.37

0.38

0.39

0.4

623 643 663 683 703 723

Sevty

Temperature (K)

Effect of Temperature on Selectivity

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Additional Specifications

Constant coolant temperature - 400 C

Constant heat capacities- low

T

Overall Heat Transfer Constant - 107 J/(m2-s-K)

Multi-tubular Reactor

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650

660

670

680

690

700

710

720

0 2 4 6 8 10

TmpaueK

Reactor Length (m)

Temperature Profiles varying Ta

693

683

673

663

653

Ta Selectivity693 0.293

673 0.326

653 0.442

Hot Spot!

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653

658

663

668

673

678

683

688

693

0 50000 100000 150000 200000 250000 300000 350000 400000 450000

TmpaueK

Catalyst Weight (kgcat)

Temperature Variance Throughout Reactor as a Function ofInlet Temperature

To = 673K

To = 663K

To = 653K

To = 683K

To = 693K

653

658

663

668

673

678

683

688

693

0 5000 10000 15000

TmpaueK

Catalyst Weight (kgcat)

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Optimal Reactor DesignInlet temperature 703 K

Reactor Volume 253.5 m3

Number of Tubes 76,535Conversion 0.860

Pressure Drop 9.97%

Selectivity 0.319

Hot spot temperature 733.3 K

Increased inlet temperature

Minimized reactor volume

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Variable Final Design OptimizedInlet Temperature (C) 400 430

Conversion 0.803 0.860

Catalyst Weight (kg) 503,000 228,175

Reactor Length 9.85 5.94

Percent Pressure Drop 8.54 9.97

Heat Gain (coolant) 1.27 1.66

Selectivity 0.326 0.319

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