Research and
Technology Initiatives
Plasma-Assisted Reforming and HydroDesulfurization of Diesel Fuels for Fuel Cells
K. Becker1, P.J. Ricatto2, J. Hunt3, and H. Ghezel Ayagh3
1 Polytechnic
Institute of New York University, Brooklyn, NY 11201
2 Stevens Institute of Technology, Hoboken, NJ 07030, USA
3 FuelCell Energy Inc., Danbury, CT 06813 USA
Objectives:
• Investigate feasibility of a low-T plasma to produce a feed gas
for High-Temperature Fuel Cells that is rich in CH4and H2 from
 A model synthetic fuel (dodecane, C12H26)
 Diesel or a Diesel/Steam mixture
• Investigate feasibility of a low-T Plasma to convert organic sulfur
compounds in Diesel to H2S (which can be scrubbed)
Work supported by the US Dept. of Energy and the US Navy and by FCE
MOTIVATION:
Research and
Technology Initiatives
The Navy’s Shipboard Fuel Cell Program
SLOGAN:
Electric Power Sources for the Navy and Marine Corps
CHARGE:
Develop new safe, efficient, environmentally friendly sources of
power and power generation concepts that support portable,
long-lived power sources for all future marine-carried
equipment and electric power sources required for all-electric
ships and other war-fighting platforms
BENEFITS:
(a) Cost savings – higher efficiency through reduced fuel
consumption & lower maintenance through reduced
shipboard load
(b) Reduced emissions – reduced exhaust emissions & reduced
acoustic and IR signature and radar cross section
Comparison of Efficiencies
Research and
Technology Initiatives
LHV (lower heating value) is the heat released by combusting a specified quantity of
fuel at 25 C and returning the temperature of the products to 150 C. The latent heat
of vaporization or water in the fuel and the reaction products is not recovered.
Additional Benefits
Research and
Technology Initiatives
• Ship design flexibility
• Modular approach that is applicable to all ship
power requirements
• Applicable to multiple platforms
• Facilitates all-electric ship with integrated power system
and zonal power distribution system
• Permits the use of alternate and synthetic fuels
Challenges
• Use of logistic fuels (JP-5, JP-7, NATO 76)
 High sulfur content (up to 10,000 ppm)
• Materials & Impurities
 Catalyst degradation
 Tolerance to CO (PEM), sulfur, etc.
 Stack life degradation
• Compact, lightweight, rugged – weight is an issue !!!
Research and
Technology Initiatives
FCE is a World Leader in Fuel Cell Systems
current
product
future
technology
FCE Direct Carbonate FC
!!!
Research and
Technology Initiatives
Fuel Cell Chemistry
2m
FCE’s 300 kW
Carbonate Direct Fuel Cell
Research and
Technology Initiatives
FCE 625 kW Ship Service
Molten Carbonate Fuel Cell System
Research and
Technology Initiatives
Process
AC Power
Two Catalytic Reactors
WEIGHT !!!
Diesel
Sulfur
Removal
PreReforming
steam
Power
Conditioning
Carbonate
DFC/SOFC
Heat/Water
Recovery
Exhaust
Steam
Generation
air
Low-T Plasma Alternative
Diesel
Plasma Reactor
Vaporization
water
Diesel  CH4,H2, HCs
R-S + H2  H2S + R
ZnO Cartridge
ZnO + H2S  ZnS + H2O
Clean Fuel
Cell Feed
Research and
Technology Initiatives
Why a Low-Temperature Plasma
• A Plasma is a collection of neutrals, ions, and electrons + more
 globally quasi-neutral, i.e. # of electrons = # of ions
 electromagnetic forces between the charge carriers are dominant
The plasma components (electrons, ions, and neutrals)
are characterized by energy distribution functions or
alternatively by an “average” energy or temperature
(Te, Ti, Tn)
Low-Temperature Plasma: Te >> Ti, Tn with Ti ≈ Tn
 high electron temperature (10,000 – 100,000 K)
 low gas temperatures (300 – 1,500 K)
 “high-temperature chemistry” at low ambient temperatures
(through electron-induced dissociation and ionization &
through molecular vibrational non-equilibrium)
!!! Plasmas are everywhere !!!
Research and
Technology Initiatives
Sun
Aurora Borealis (Northern Lights)
Fluorescent Lamps
Flame
Lightning
Plasma Display Televisions
Dielectric Barrier Discharge Plasmas
Research and
Technology Initiatives
Research and
Technology Initiatives
Plasma Reactor I
SDM P REACTO R
1. Surface DBDs (S-DBDs) using Microrods
IN
High Voltage
(~10-15 KHz)
Dielectric
Ground Wires
P lasm a
Copper
W ire
Plasma Reactor II
2. Parallel-Plate DBD (PP-DBD)
Research and
Technology Initiatives
Top electrode removed
Gas in
Gas out
10”
Results I: Preliminary Results
(1) Low & High Sulfur Fuel @ Steam/Fuel = 3
Good
Not
bad
Research and
Technology Initiatives
Low Sulfur
High Sulfur
27 % (v/v)
23
30
5
1/0
14
28
23
29
2
2/0
16
Methane
Hydrogen
Ethene
Acetylene
Ethane/Propane
Higher Hydrocarbons
(2) Effect of Steam/Fuel Ratio for NATO 76 Diesel
Good
Not
bad
Methane
Hydrogen
Ethene
Acetylene
Ethene/Propane
Higher Hydrocarbons
LOW (2:1)
25 % (v/v)
21
28
4
2/1
MEDIUM (3:1)
27
23
30
5
1/0
HIGH (8:1)
25
21
33
4
1/0
19
14
16
Preliminary Results Look Promising, BUT:
• obtained under very favorable circumstances
• ignore other important parameters
• not the basis for realistic implementation – but justified more research
Research and
Technology Initiatives
Results II: (1) Effect of Fuel Flow
on Dodecane Conversion
Fuel Flow, g/m
0.8
0.4
% Conversion
3.4 %
7.0 %
Results II: (2) Effect of Plasma Power
on Dodecane Conversion
Plasma Power, W
% Conversion
100
300
3.4 %
4.2 %
Concentration, mol % (dry basis)
Concentration, mol % (dry basis)
H2
17.6
14.2
CH4
1.0
1.2
CO
0.3
0.3
H2
17.6
9.1
CH4
1.0
2.0
CO
0.3
0.2
CO2
0.2
0.1
CO2
0.2
0.1
C2H6
0.7
0.7
C2H6
0.7
0.9
C3H8
1.2
1.6
C3H8
1.2
2.7
C4-C7
1.7
2.1
C4-C7
1.7
2.3
Results II: (3) Effectiveness of Hydrodesulfurization by Plasma
Carrier Gas
N2
Air
Air
Gas Flow, cc/m
250
200
200
Plasma Power, W
50
50
10
3.0 %
3.3 %
2.3 %
1.2
36.6
5.7
JP-5 Conversion, %
Total S in Gas
Stream, ppm
O needed !
Research and
Technology Initiatives
Results II: (4) Plasma Reforming of JP-5
Reactor
PP-DBD
C-DBD
Carrier gas
Argon
Air
Nitrogen
Gas flow (slpm)
0.25
0.25
0.25
Fuel Flow, g/m
0.5
0.5
0.8
1.6%
4.9%
3.0%
Fuel Conversion,
%
Concentration, mol % (dry basis)
H2
8.4
10.8
3.5
CH4
0.1
2.0
0.7
CO
0.6
4.6
0.1
CO2
0.3
0.7
0.0
C2H6
0.2
0.8
0.4
C3H8
0.3
1.5
1.8
C4-C7
0.8
1.5
1.9
SUMMARY OF FINDINGS
Research and
Technology Initiatives
• Plasma-assisted partial oxidation of hydrocarbons in the presence
of steam gives substantially better % conversion compared with
straight steam reforming or straight partial oxidation. This
suggests that while the primary conversion pathway is via partial
oxidation, the steam plays an important role in the conversion.
• While the % conversion and electrical efficiency (both <10%) are
well below those required for immediate practical application, the
composition of the CH4/H2-rich product gas is suitable for the
anode feed of a SOFC.
• Preliminary results show that the plasma assisted conversion of
organic sulfur compounds to hydrogen sulfide is much greater
than the hydrocarbon % conversion, suggesting that the plasma
selectively enhances sulfur chemistry.
 May need 2 separate plasma reactors (cf. 2 catalytic reactors)
Next Steps
Research and
Technology Initiatives
• Conduct parametric studies to optimize each of the following:





Power Deposition into the Plasma
Reactor Temperature
Fuel/air/steam ratio
Fuel flow rate
Carrier gas choice and flow rate
• Further optimize the reactor design and material selection to
maximize % conversion and reactor durability, and minimize
thermal problems and carbon deposition.
• Incorporate heterogeneous reforming catalysts (hybrid system).
• Other types of plasmas (e-beam sustained, gliding arc).