Sulfur Tolerant Liquid Fuel Reformer
S. Elangovan, Joseph Hartvigsen, Piotr Czernichowski (Ceramatec)Albin Czernichowski (ECP, France)
2425 South 900 WestSalt Lake City, UT 84119-1517
SECA Core Technology Program WorkshopSession: Balance of Plant
Lakewood, COOctober 27, 2005
2
Liquid Fuel Advantage
Energy DensityJP-8 43 MJ/kg, 0.76 to 0.84 kg/literDiesel 42 MJ/kg, 0.86 kg/literHydrogen at 680 bar (10,000 psi, 23100’ head) Z=1.43
4.35 MJ/liter (min. work of compression is 10-12% of LHV)
StorabilityNon-pressurized (tank cost & energy release issues)No boil-off, e.g. LNG or LH2
AvailabilityHighly developed infrastructureOnboard as road engine fuel
Fuel Choice
3
Military, Commercial and Consumer APU Markets
Class A Motor home Silent APU
Class 8 Truck Hotel PowerEliminate Road Engine Idling
Silent Mobile Electric Power
Applications
4
Obstacles to Use of Liquid FuelsSulfur
Poisons steam reforming catalystsCorrosive effect on system BOP
Aromatics, Alkenes, Alkynes, and Alicyclic hydrocarbons
Hydrogen lean mixtures, empirical formula CH2-δ
Prone to soot and coke formationDeactivation of steam reforming catalystsOperational problems to POx, CPOx, ATR, etc.
VaporizationFinal Boiling Point near thermal decomposition T
Challenges
5
The SOFC Advantage in Heavy Fuel Applications
High Operating Temperature& Oxygen Ion Conducting Electrolyte
=> Fuel Flexibility
CO as a fuel not a poisonOn anode reformation of hydrocarbon slipBetter sulfur toleranceNo thermodynamic penalty for nitrogen dilution
Ratio of pH2O / pH2 unaffected by fuel diluents Reversible Driving Potential:
Erev = EN0 T( )+
RTnF
ln pH 2O
pH 2 pO2
⎛
⎝ ⎜ ⎜
⎞
⎠ ⎟ ⎟
SOFC Benefits
6
SOFC Utilization of CO, Light HC
Fuel Feed: H2, H2O, CO, CO2, CH4
O= flux
Air Flow
CO, CO2
H2, H2O
CO, CO2
H2, H2O }Shift CO, CO2
H2, H2O{CO, CO2
H2, H2O
Reforming Reaction
CH4 + H2O <= Ni Catalyst => CO + 3H2
Shift Reaction
CO + H2O <==> CO2 + H2
O= flux
Air Flow
CO, CO2
H2, H2O
CO, CO2
H2, H2O
CO, CO2
H2, H2O+ HC
Ni Cermet Anode H2O
SOFC Benefits
Reformer Description
Operating PrincipleFeatures & Benefits
8
Cold Plasma GlidArc Operation
ignition expansion & work extinction
Electrode Elec
trod
e
Reformer Principle
9
Cold Plasma Reformer Features
Sulfur insensitiveNo reformation catalyst
Unaffected by SulfurNo deactivation over time
Fuel flexibilityLight to heavy hydrocarbons
Variable operating temperature (set by equilibrium thermodynamics)
700 - 900oC typical — matching SOFC operation window
Reformer Benefits
10
Cold Plasma Reformer
Very high reaction zone activityCompact reformer sizeSoot free operation
Low power requirement for non-thermal plasma
2% of fuel feed rate heating value4% of generated power (at 50% FC efficiency)8% of heat of reformation60 - 80oC reformate sensible temperature rise
Reformer Features
11
GlidArc Liquid Fuel Reformer5 kWt fuel rate, 0.6 liter, Atmospheric Pressure
Reformer
Height 12”OD: 4.5”
JP-8 Reformation
Air Force SBIR Phase II
13
JP-8 Analysis
14
Reformate Compositional Stability
0
10
20
30
40
50
60
0 4 8 12 16 20Run time (hours)
CO
H2
H2OCO2
N2
CO + H2
Fuel: JP-8
15
Reformate Hydrocarbon Slip
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0 4 8 12 16 20Run Time (hours)
CH4
C2H4
C2H6, C2H2
Fuel: JP-8
Commercial Diesel(non-desulfurized)
Air Force SBIR Phase IICeramatec IR&D
17
Long-term Operation
Continuous operationReformation: 100 hoursIncluding hot stand by: 250 hours
0
200
400
600
800
1000
1200
0 50 100 150 200 250 300 350 400
Elapsed Time (hours)
Reformation Zone
Thermal Mass
Air Preheat
Reformer Exit
Fuel: Commercial diesel
18
Reformer Start-up Time
Manual Control30 minutes to temperature60 minutes to steady state
0
200
400
600
800
1000
1200
0 20 40 60 80 100
Elapsed Time ( Min )
Reformation Zone
Thermal Mass
Air Preheat
Reformer Exit
Fuel: Commercial diesel
NATO F-76
Navy SBIR Phase I
20
F-76 Specification
MIL-PRF-16884K Hydrogen content (wt% min) 12.5%Sulfur content (wt% max) 1%
Fuel: F-76
21
High Sulfur Fuel Reformate
Fuel: F-76
H2
CO
H2+CO
CO2
N2
0
10
20
30
40
50
60
70
Volu
me
Perc
ent
CH4
C2H4
C2H6
C2H20.0
1.0
2.0
3.0
4.0
5.0
Vol
ume
Perc
ent
22
SOFC Test of JP-8 Reformate Slip Stream
Stack Test
23
SOFC Stack on JP-8 Reformate
Stack Test
0
10
20
30
40
50
60
70
80
100 125 150 175 200 225 250 275 300
Time (Hrs)
Hydrogen Hydrogen
JP-8 Reformate(desulfurized)
DAQlock-up
JP-8 Reformate(desulfurized)
Hydrogen
24
Stack Test Results Three tests conducted
Two 10-cell stacksPair of 11-cell stacks
Performance comparable to hydrogen baseline
Power output difference correlates with reformate Nernst potential depressionSome cooling of stack due to presence of hydrocarbon in the reformate
Soot free operation demonstratedNo soot found in fuel manifolds or electrodes
Stack Test
25
Post Test AppearanceFuel Electrode
Stack Test
26
Button Cell Test on Diesel Reformatenon-desulfurized raw reformate
0.0
0.2
0.4
0.6
0.8
1.0
0 0.2 0.4 0.6 0.8 1
Current Density (A/cm2)
Cell
Volt
age
(V)
0
0.1
0.2
0.3
0.4
0.5
Pow
er D
ensi
ty (
W/c
m2 )
cell no. 73Fuel: diesel reformate180um Sc-doped zirconia electrolyteTemp: 850°C
ASR=0.67 ohm-cm2
Commercial Diesel / Button Cell
Cell ASR similar to H2/H2O fuel
27
On JP-8 ReformateLower Nernst potential (~ 100 mV)Presence of H2S (~ 50 ppm)Cell cooling from methane reformation (~2% methane)
Button Cell Test on JP-8 ReformateNon-desulfurized raw reformate
JP8CELL10245Temp: 800°C
Cell Voltage: 0.7 Velectrolyte: ~180 micron ScSZ
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0 2 4 6 8Time (Hours)
Curr
ent
Den
sity
(A/
cm2 )
Hydrogen - 3% H2O Hydrogen - 3% H2O
Raw JP-8 Reformate(no desulfurization)
28
Work in ProgressProcess Optimization
Effect of fuel equivalence ratio (φ)
Size scale up
20 kWt ReformerHeight: 12”
OD: 7”5 kWt Reformer
Height: 12”OD: 4.5”
Present focus
29
Remaining ChallengesProcess optimization
Mapping reformate composition as a function of temperature, fuel/oxidant ratio, and residence time
SOFC integration testReformer re-design in progress (Air Force)
Start up time reductionUninterrupted extended operationTurn down
30
AcknowledgementsUS Air Force
Hill Air Force Base, Air Logistics CenterJoe BurnsPhase II SBIR Grant No. F42650-03-P-2750
US NavyNAVSEA, PhiladelphiaBrian Prew and Don HoffmanPhase I SBIR Grant No. N655538-05-M-0145
Ceramatec, Inc.IR&D Funding
