Reformate Desulfurization for Logistic ...€¦ · Reformate Desulfurization for Logistic...

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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