Oxygen-Containing Contaminants and Steam Cracking ...
Transcript of 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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Steam Cracker
Oxygen containing compounds
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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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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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Modeling
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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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SIMCO
CRACKSIM
Furnace
COILSIM1D
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• 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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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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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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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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Introduction of new species and radicals which can interact with hydrocarbon matrix
+
Validation
Pilot plant of LCT - UGent
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• 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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• 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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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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Simulated vs experimental data
– Temperatures: 800 - 860 °C
– Conc. Oxygenates: 0 – 2 wt%
Outline
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• 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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Wrapping up
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• 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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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