Reformate Desulfurization for Logistic SOFC Power SystemsSOFC Power SystemsSOFC Power Systems
Hongyun Yang1, Troy Barron1 and Bruce Tatarchuk2
1. IntraMicron Inc., 368 Industry Drive, Auburn, AL, 36832, y , , ,2. Dept. of Chem. Eng., Auburn University, AL, 36849
June 16, 2010
th 44th P S C f
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the 44th Power Sources ConferenceLas Vegas, NV
IntraMicron Inc.
IntraMicron Inc is a small business company located at Auburn, AL. Its R&D (1) Filt ti (2) D lf i ti (3) Fi h T h S th i (4) COcovers:(1) Filtration; (2) Desulfurization; (3) Fischer Tropsch Synthesis; (4) CO
oxidation.
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Microfibrous Entrapped Catalyst Particles
Polishing sorbents for gas phase desulfurization
Adsorbent for liquid phase desulfurization
Desulfurization Sorbents/Adsorbents
70
80
t)
Cu-ZnO/SiO2Low Temperature Gas Phase
40
50
60
70
of S
/ g o
f Sor
bent Fe-ZnO/SiO2
Co-ZnO/SiO2Ni-ZnO/SiO2
Mn-ZnO/SiO2
ZnO/SiO2
Commercial ZnO
Desulfurization Sorbent: Cu-ZnO/SiO2, (Patent Applied for)
10
20
30
40
BT
Cap
acity
(mg
ZnO(Regn)
Liquid Phase Desulfurization Adsorbents:Ag2O/TiO2 for JP-5
0Sorbents
After Desulfurization
Current capacity: ~6 mg S/g adsorbent
Ultralow Sulfur Diesel Sample
DMDBT and Derivatives
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Outline
• Sulfur IssueSulfur Issue• Reactor Design and Bed Configuration• Desulfurization & Regeneration Performance• Desulfurizer ConstructionDesulfurizer Construction• Conclusion
A k l d• Acknowledgements
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Sulfur Issue
• Typical Fuel Cells Have Low Sulfur Threshold: – 0.1 ppmv most for PEM Fuel Cells– 2~3 ppmv for typical Solid Oxide Fuel Cells
• Sulfur Content in Logistic Fuels (ca JP-5 JP-8)Sulfur Content in Logistic Fuels (ca. JP 5, JP 8) – i.e. 500~3000ppmw, equivalent to 50~300 ppmv after converted
to reformates in reformers.• Sulfur Removal Techniques• Sulfur Removal Techniques
– Pre Reformer Desulfurization– Post Reformer Desulfurization
• Post Reformer Desulfurization Using Reactive Sorbents– ZnO, CuO, Fe2O3 etc.– High sulfur capacity (i.e. 392 mg S/g ZnO), compared to g p y ( g g ), p
adsorbents for liquid phase desulfurization.
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Objectives
• To build a desulfurizer able to• To build a desulfurizer able to– Reduce total sulfur concentration to less than 3 ppmv– Provide a continuous run of 200 hours– Have a good low temperature performance for cold g p p
startup and transient operations– Small bed size: ~1 foot longSmall bed size: 1 foot long– Low pressure drop ca. 1-2 psi
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Cyclic Arrangement and Transition OperationTransition Operation
Start with heating
5hours 4hours 1hour Transition
Time balance=
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Reactor/Valve Sizes
Preferred desulfurization temperature: 400 CPreferred desulfurization temperature: 400 C
Preferred regeneration temperature: 600 C
Parameter Value ResultParticle size 0.8~1.4 mm Regn <5 hourReactor diameter 6” 60 cm/sBed length 12” L/D=2Pipe /valve size 2” 6 m/s
P=1.4 psi
Note:
The system works at 400 C during desulfurization and 600 C during regeneration.
Pipe /valve size 2 6 m/s
y g g gTherefore the valves are required to work at high temperature in the presence of oxygen during regeneration.
S lf i t 300
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Sulfur input: 300 ppmv
Design Challenges
Reformates:Flow rate: 17 kg/hr .Temperature from reformer: 850 CReformate Composition:
High flow rate: Pressure DropHigh Temperature: Need heat exchanger
Component Concentration
CO 24.9%
g
High CO and CO concentrationCO2 10.2%
WATER 6.9%
H 25 0%
High CO and CO2 concentration,COS formation.CO2+H2S=COS+H2OCO+H S COS+HH2 25.0%
N2 33.0%
H2S 300 ppmv
CO+H2S=COS+H2
2 pp
Breakthrough Concentration: 2~3 ppmv Run time: 200 hours Regenerable
Small Reactor Good Low Temperature Performance for Cold
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Pressure Drop: < 2 psi Startup and Transient Operations.
Desulfurization Performance COS Equilibrium AnalysesCOS Equilibrium Analyses
CO(g)+H2S(g)=COS(g)+H2(g) (slow homogeneous reaction)
(1) Experimental results suggest the COS formation via CO is slow the outlet
CO2(g)+H2S(g)=COS(g)+H2O(g) (fast heterogeneous reaction)
(1) Experimental results suggest the COS formation via CO is slow, the outlet COS concentration is about 6 ppmv at test conditions in a blank tube.
(2) COS formation via CO2 requires catalysts such as ZnS
(3) COS is difficult to be captured by ZnO sorbent. Hydrolysis is required
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reformate composition: 25% CO, 25%H2, 10% CO2, 7% H2O and 33% N2.
Effects of CO and CO2
84.0
6
7
3.0
3.5
(ppm
)
FreshRegn 1
Need sorbents for COS removal or conversion 4
5
2.0
2.5
centration
0.1ppm
2
3
1.0
1.5
Sulfu
r Con
1.8 ppm1.7 ppm
add 25% CO
add 10% CO2
remove CO
0
1
0.0
0.5
0 50 100 150 200 250 300 350
0.2 ppmadd 25% CO
CO+H2S=COS+H2 K=0.0363 Ce=10.4 ppmv; CO2+H2S=COS+H2O K= 0.0029 Ce=1.2 ppmv
Time (min)
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Breakthrough curves of layered beds tested with 300 ppmv H2S-25% H2-25% CO-10% CO2-7% H2O-33% N2 at a face velocity=100 cm/s at 400 C. Bed length: 22 cm
Bed ConfigurationLayered Bed Design
Desulfurization
Layered Bed Design
• Low outlet sulfur concentration (as low as 0.3 ppmv)
• Less weight
Desulfurization
High capacity• Less weight• Short regeneration time• Low temperature function
Commercial ZnO bed (10 cm)
High capacityLong regn. timeHigh densityPoor contacting
p• Bed Configuration
– Down flow direction (in desulfurization)
(10 cm)
l it– (in desulfurization)– Diameter: 2.14 cm– Particle size: 0.8~1.4 mm
S d b
Supported ZnO sorbent bed (12 cm)
low capacityshort regn. timelow densityhigh contacting efficiency
– Supported sorbent: ZnO/SiO2 and supported Cu doped ZnO sorbent which has a better low temperature performance Regeneration
y
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performance. g
Layered- Bed Performance
(1) Allow multiple stop and resumestop and resume(2) Run time can be extended if necessarynecessary.
Desulfurization was carried out at 400 C in the presence of reformates containing 300ppmv H S 25% H 25% CO 10% CO 7%H O 33% N at a face velocity of 60
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300ppmv H2S-25% H2- 25% CO-10% CO2-7%H2O-33% N2 at a face velocity of 60 cm/s.
Cyclic Test(Layered Bed of ZnO-ZnO/SiO2)(Layered Bed of ZnO ZnO/SiO2)
2 50
2.00
2.50
pmv)
2 beds
1.50
entr
atio
n (p
p 2 beds
30 cycles/bed
5 hrs/cycle
0.50
1.00
ulfu
r con
ce
1st cycle
30th cycle
y
Total is 300 hours.
0.00
0.50
0 100 200 300 400 500 600
Su
0 100 200 300 400 500 600
Time (min.)
Desulfurization was carried out at 400 C in the presence of reformates
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pcontaining 300 ppmv H2S-25% H2- 25% CO-10% CO2-7%H2O-33% N2.
Reduced Regeneration Time
Sorbent can beSorbent can be regenerated in a shorter time;
Sorbent bed can beSorbent bed can be stop and resume multiple times during the runthe run.
Sorbent bed can provide a longer service time.
Tested with challenge gas containing 300 ppmv, 30% CO, 32% H2, 30% N2 and 8% H2O at a face velocity of 1.0 m/s at 400 C. The sorbent bed contains 56 g of 1 2 mm ZnO particles with a bed length of 10 cm and ZnO/SiO of 12 cm Spent
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1.2 mm ZnO particles with a bed length of 10 cm, and ZnO/SiO2 of 12 cm. Spent sorbent was regenerated in air-steam mixture containing ~14% O2 for 4 hours.
Low Temperature Performance
9.0
7.0
8.0
9.0pp
mv)
ZnO Bed Fresh
4 0
5.0
6.0
entr
atio
n (p Layered Bed Fresh
Layered Bed Regn 1Layered Bed Regn 2
2.0
3.0
4.0
ulfu
r Con
ce
0.0
1.0
0 50 100 150 200 250 300 350
Su
Desulfurization was carried out at 150 C in the presence of reformates
0 50 100 150 200 250 300 350
Time (min)
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pcontaining 300 ppmv H2S-25% H2- 25% CO-10% CO2-7%H2O-33% N2.
Off-Site Regenerable Desulfurizer(Sulfur Cartridge)(Sulfur Cartridge)
• Single reactor provides a run time of 200 hours.g p
3 0
3.5
mv)
0-5 hr at 300 ppmv H2S
2 0
2.5
3.0
trat
ion
(pp 0 5 hr at 300 ppmv H2S
5-180hr at 2100 ppmv H2S180-200hr at 300 ppmv H2S
1.5
2.0
r Con
cent
0.5
1.0
utle
t Sul
fu
0.00 50 100 150 200 250
Ou
Equivalent Time (hour)
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Desulfurization was carried out at 400 C in the presence of reformates containing 300ppmv H2S-25% H2- 25% CO-10% CO2-7%H2O-33% N2 at a face velocity of 60 cm/s.
Desulfurizer ConstructionSorbent Loaded for DesulfurizerSorbent Loaded for Desulfurizer
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Conclusion
• The layered bed made of commercial ZnO andThe layered bed made of commercial ZnO and supported ZnO based sorbent demonstrated a wide operational temperature window (150~400 C).
• The layered bed are highly regenerable. It can be regenerated for 30 cycle without significant changes in desulfurization performance.
• The designed desulfurizer can provide a continuous run with regeneration or 200 hours run as a sulfur cartridge.
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AcknowledgementsAcknowledgements
Award #: W56HZV-07-C-0577
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Thank you for your attention
Questions?Q
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