oxygen-containing contaminants and steam cracking

Oxygen-Containing Contaminants and Steam Cracking: Understanding their Impact Using

COILSIM1D

Ismaël Amghizar1, Andrés E. Muñoz G.2, Marko R. Djokic 1,

Kevin M. Van Geem1, Guy B. Marin1

1 Laboratory for Chemical Technology, Ghent University - www.lct.UGent.be2 AVGI – www.avgi.be

2017 AIChE Spring Meeting – 29th Ethylene Producers’ Conference

San Antonio - TX, USA, March 27th, 2017 1

Steam Cracking

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Steam Cracker

Oxygen containing compounds

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Typical contaminants in the feed Bio based species

Light

Naphtha

BF

Water

Furnace Steam drum

HP Steam

Dilution

Steam

Quench Oil

TowerStrippers

Quench Water

Tower

Dilution Steam

GeneratorCompressors

PFO Pygas

Waste Water Spent Caustic

Caustic

Tower

Caustic

Wash Water

Dryers

38°C

14.5 bar

10°C

13.5 bar

1.4 bar

28°C

11.8 bar

Quench

water

8.5 bar

steam

56°C71°C

HP depropanizer LP depropanizer

35 bar

13°C

38 bar

65°C

Quench

water

To Hydrogen recovery

-98°C

-37°C

36 bar

demethanizer

Methane to cold box

-99°C

-5°C

20°C

32 bar

32 bar

Quench

water

debutanizerdeethanizer C2 slpitter

Ethylene

-38°C

-38°C

40°C

16 bar-77°C

4 bar

-38°C

C4's

C5's85°C

propane

propylene

C3 slpitter

Steam Cracking

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Methanol

Acids

Formaldehyde

CO/CO2

Gum formation

K. M. Van Geem, G. B. Marin, N. Hedebouin, J. Grootjans, Energy efficiency of the cold train of anethylene cracker, Oil Gas-European Magazine 34 (2008) 95-99

• Introduction

• Reactor and kinetic model

• Simulations and Results

• Conclusions

Outline

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Modeling

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

The solution:

– COILSIM1D

• Detailed Chemistry

• 1D reactor model

• Feed reconstruction

• Reasonable computational times

The challenge:

– Complex chemistry

• Large number of species

• Large number of reactions

– Reactor model

– Unknown mixture

Key elements of COILSIM1D

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

SIMCO

CRACKSIM

Furnace

COILSIM1D

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

• Broadest kinetic model for steam crackingo 720+ molecules

o 43 radicals

o 300,000+ reactions

• Based on high level Ab initio data, and validated (pilot and industrial)

Kinetic model

1D reactor model

CRACKSIM

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Free radical mechanism

3 main reaction families:

1. C–C and C–H scission of molecules and reverse radical–radical recombination

𝑅1 − 𝑅2՞𝑅1• + 𝑅2

•

2. H abstraction reactions (intra- and intermolecular)

𝑅1 − 𝐻 + 𝑅2• ՞ 𝑅1

• + 𝑅2−𝐻

3. Radical addition to olefins and reverse β-scission of radicals, both intra- and intermolecular

𝑅1• + 𝑅2 − 𝑅3 ՞ 𝑅1 − 𝑅2 − 𝑅3

•

CRACKSIM

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Assumption for accurate network of manageable size

• μ-hypothesis: bimolecular reactions can be neglected for certain radicals (C6+)

• PSSA for large radical species

Kinetic model consists of two parts:

•β-network: network with elementary reactions of C5- radicals

•μ-network: describes the thermal decomposition of large molecules

PRIM-O

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

De Bruycker, R. Production of green base chemicals through conventional and emerging pyrolysis processes. Ghent University, 2016.

k1k2

k3

k4k5 k6 k7

Inclusion of oxygenates

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Introduction of new species and radicals which can interact with hydrocarbon matrix

+

Validation

Pilot plant of LCT - UGent

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

• Fire-heated Furnace

• Reactor: 12.8 m long

• 7 independently heated cells

• Online analytics:

– Permanent Gas Analyzer

– Refinery Gas Analyzer

– Detailed HC Analyzer

– GCxGC-FID/TOF-MS

– Light Oxygenates Analyzer

– CO / CO2 detector

Outline

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

• Introduction

• Reactor and kinetic model

• Simulations and Results

• Conclusions

Simulation cases

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Two contaminants:

– Methanol

– DME

Two illustrative cases:

Simulation cases

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Naphtha composition

– Reconstructed from commercial indices using SIMCO

Commercial indices of the naphtha feed

Specific density [kg/m³] 708.8

ASTM D86 [°C]

IBP 39 50% 99 FBP 165

PIONA [wt%]

Paraffins 36.5 Iso-paraffins 32.8 Olefins 0.0 Naphthenes 21.4 Aromatics 9.20

Reconstructed feed

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CH3OH H2 CH4

C2H4 C3H6 C4H6

CO CO2 CH2O

Results: Case I

Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

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DME H2 CH4

C2H4 C3H6 C4H6

CO CO2 CH2O

Results: Case II

Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Validation

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Simulated vs experimental data

– Temperatures: 800 - 860 °C

– Conc. Oxygenates: 0 – 2 wt%

Outline

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

• Introduction

• Reactor and kinetic modeling

• Simulations and Results

• Conclusions

• CRACKSIM has been extended with the thermal decomposition of

oxygenates

• COILSIM1D can explicitly account for the effect of oxygenates on reactor

outlet yields

• Presence of oxygen compounds in the feed negatively impact the yields

of valuable products

Wrapping up

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Wrapping up

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

• The simulated cases (methanol and DME) showed an increased yield of

CO, CO2 and formaldehyde, compared to pure HC feed

• Validation with pilot plant experiments showed good agreement of the

model for a broad range of conditions

Acknowledgements

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

The Long Term Structural Methusalem Funding

Questions

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Ethylene Producers’ Conference, San Antonio - TX, Mar 27th 2017

Oxygen-Containing Contaminants and Steam Cracking: Understanding their Impact Using

COILSIM1D

Ismaël Amghizar1, Andrés E. Muñoz G.2, Marko R. Djokic 1,

Kevin M. Van Geem1, Guy B. Marin1

1 Laboratory for Chemical Technology, Ghent University - www.lct.UGent.be2 AVGI – www.avgi.be

2017 AIChE Spring Meeting – 29th Ethylene Producers’ Conference

San Antonio - TX, USA, March 27th, 2017 25