Embed Size (px)
Citation preview
A Novel Membrane Reactor for Hydrogen Production from Coal
Shain J. Doong, Francis Lau, and Estela Ong
Gas Technology Institute
May 23-26, 20052005 DOE Hydrogen Program Review
Project ID PDP24
This presentation does not contain any proprietary or confidential information
OverviewTimeline> Start: 9/9/2003> End: 9/8/2005> Percent complete: 80%
Budget> Total project funding: $602,816
–DOE share: $482,247–ICCI share: $100,569–AEP share: $20,000
> Funding received in FY04: $352,700> Funding for FY05: $250,116
Overview (con’t)Barriers>High cost of coal to hydrogen
>Mature technologies employed for coal to hydrogen process –difficult to improve and reduce cost
Targets>Reduce cost of hydrogen by 25% compared to current coal-based plants by 2015
(DOE Fossil Energy Hydrogen Program Plan, 6/2003)
Partners>Dr. Jerry Lin of Arizona State University
>Dr. Eric Wachsman of University of Florida
Project Objectives
> Determine the technical and economic feasibility of a membrane reactor coupled with a coal gasifier for clean, efficient, and low cost production of hydrogen from coal.
> Screen and test candidate membranes under high temperature and high pressure conditions of coal gasification
Technical ConceptHydrogen from Coal via Gasification
Conventional gasifier
GasifierGas cleaning
Shift reaction
H2separation
coal
Oxygen/steam hydrogen
Membrane gasification reactor
Gasifier
membrane
hydrogencoal
Oxygen/steam
Gas cleaning
CO2removal CO2
Power generation
Combine hydrogen separation, reforming, shift and gasification reactions in a close coupled way or within one reactor
Potential Benefits of Membrane Reactor for Hydrogen Production from Coal/Biomass> High H2 production efficiency:
– Thermodynamic analysis and recent modeling work indicate over 40% improvement in H2 production efficiency over the current gasification technologies
> Low cost: – reduce/eliminate downstream processing steps
> Clean product:– no further conditioning needed, pure hydrogen
> CO2 sequestration ready: – simplify CO2 capture process
> Power co-generation: – utilization of non-permeable syngas
Approach
> Membrane Materials Screening and Testing– Design and construction of a membrane permeation
apparatus– Testing candidate membranes at high temperatures and
high pressures
> Conceptual Design of Membrane Reactor – Modeling– Membrane gasifier configuration
> Process Evaluation and Flow Sheet Development
> Economic Evaluation for Overall H2 Production Process
Accomplishments
> Constructed and commissioned a high temperature/high pressure (1100oC/1000 psi) membrane permeation unit.
> Developed fabrication techniques for making supported and unsupported ceramic membranes.
> Demonstrated high hydrogen flux for proton-conducting perovskite membranes in the high pressure membrane permeation unit.
> Developed membrane gasification reactor model and confirmed the improved hydrogen production efficiency (30-50%).
> Began evaluation of chemical stability issues for the perovskitematerials.
GTI High Temperature/High Pressure Permeation Unit
•Membrane diameter:1.25”
•Max Temp: 1100oC
•Max Pressure:1000 psi
hydrogen
Inertsweeping
gas
membrane
Cylindricalheater
non-permeate
permeate
Inner tube
Outer tube
Perovskite Identified as Leading Candidate Membrane Material
> Perovskite membranes evaluated:– BaCe0.9Nd0.1O3-α (BCN)
(supported or unsupported)– BaCe0.8Y0.2O3-α (BCY)– SrCe1-xEuxO3-α (SCE)– SrCe0.95Tm0.05O3-α (SCTm)
Membrane Fabrication
> Die pressing or tape casting for self supporting membranes
> Tape casting and lamination for supported thinner membranes
Hydrogen at high pressure e-
e-
H+
Mixed proton/electron conducting membrane
H2 2H+ +2e- 2H+ +2e- H2 H+
Hydrogen at low pressure
Hydrogen at high pressure e-
e-
H+
Mixed proton/electron conducting membrane
H2 2H+ +2e- 2H+ +2e- H2 H+
Hydrogen at low pressure
Developed Supported Ultra-Thin Membrane
Membranes prepared by uniaxially pressing of disk
200 micron dense layer
Hydrogen Flux Measured from High Pressure Permeation Unit
0.00.10.20.30.40.50.60.70.80.91.0
0 2 4 6 8 10 12 14H2 feed pressure, atm
H2
flux,
STP
CC
/min
/cm
2
950C900C50/50 H2/He feed, 900C
BCN, 0.22 mmunsupported
0
0.1
0.2
0.3
0.4
0.5
0.6
0 2 4 6 8 10 12 14Feed H2 Pressure, atm
H2
flux,
STP
CC
/min
/cm
2
BCN, 0.2 mm supported950C
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 2 4 6 8 10 12 14Feed H2 Pressure, atm
H2
flux,
STP
CC
/min
/cm
2
100% H2P=8.14 atm, with He60% H2P=1 atm, with He100%H2, 2nd sample
SCTm, 1.7 mmunsupported950C
0
0.1
0.2
0.3
0.4
0.5
0 1 2 3 4 5 6 7Feed H2 Pressure, atm
H2
flux,
STP
CC
/min
/cm
2SrCe0.8Eu0.2O3-α 0.34 mmunsupported950C
Temperature Dependency of Proton-Conducting Membranes
Activation energy 27 Kcal/mole for SCTm
12 Kcal/mole for BCN
0.01
0.10
1.00
10.00
0.950.900.850.820.780.76Tem perature, 1/K*1000
H2
flux,
STP
CC
/min
/cm
2
105311161173122312831313Tem p, K
SCTm, 1.7 m m thickness at 3 atm
BCN, 0.2 m m thickness at 1 atm
Proton-Conducting Membrane Shows Good Long Term Stability Under Reducing Environment
SCTm membrane with pure hydrogen at feed and nitrogen as sweep gas at 1 atm
•Temperature drifted during the testing and was lowered to the original value at 170th hour.
0.5
0.55
0.6
0.65
0.7
0.75
0 50 100 150 200 250 300time, hr
H2 fl
ux, c
c/m
in/c
m2
980
1000
1020
1040
1060
1080
1100
Tem
p, C
fluxtemp
Key Conclusions from Membrane Permeation Testing> Several barium/strontium cerate-based perovskite
membranes show reasonable hydrogen flux at gasification temperatures
> Hydrogen flux increases with pressure (to about 4 bar) and temperature
> The perovskite membrane can operate more than 200 hours under a pure hydrogen feed condition at 1000C
> Proton conducting perovskite membranes are good candidate materials for gasification membrane reactor applications
Dense membrane of BCN shows stronger resistance to CO2than powder form
Zr-doped barium-cerate perovskite shows stronger resistance to CO2
Evaluation of Chemical Stability for Perovskite Materials
- TGA (Thermo Gravimetric Analysis) Study
Evaluation of Chemical Stability for Perovskite Materials
- TGA (Thermo Gravimetric Analysis) Study
Dense membrane of BCN shows stronger resistance to H2S than powder form
Membrane Gasification Reactor Modeling- Matching reaction kinetics and hydrogen permeation rate
coal synthesis gas
hydrogen
H2 H2
pH2f
gas phase reaction
H2O+CO = CO2+H2
CH4+H2O = CO+3H2
(CH4+CO2 = 2CO+2H2)Reaction rates estimated from chemical kinetics:
14 species, 32 reaction steps
Karim & Metwally (1974)
non-permeate
pH2p
F: Faraday constant
L: membrane thickness
: proton conductivity
: electronic conductivity
Membrane tube( ))ln()ln(
))((4 22
2
2pH
fH
elH
elH
H
ppLF
RT
J
−+
−
=
+
+
σσσσ
+Hσ
elσ
Ambipolar Conductivity Calculated From Measured Hydrogen Flux
( )))ln()ln(4
/())((
222 2pH
fHH
elH
elH ppLF
RTJ −−=++
+
σσσσ
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 1 2 3 4 5 6 7 8 9
Feed H2 Pressure, atm
H2
flux,
STP
CC
/min
/cm
2
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
Am
bipo
lar
cond
uctiv
ity, S
/cm
fluxconductivity
SCTm 1.7 mm950C
Membrane Gasifier Dimensions - a conceptual design example
hydrogen
retentate
From gasification zone
retentate
coal feed, TPD 1000oxygen feed, TPD 600steam feed to gasifer, TPD 595steam feed to shift reactor,TPD 270coal syngas flow rates, Nm/hr 97125temperature, C 1100pressure, atm 60gasifier diameter, cm 330membrane tube diameter, cm 1.250membrane thickness, cm 0.0025membrane tube length, cm 900number of membrane tubes 21300membrae area, m2 7550ambipolar conductivity, S/cm 0.05gas residence time of mem., sec 8
Modeling of Membrane Gasification Reactor
0
50
100
150
200
250
300
350
0 0.2 0.4 0.6 0.8 1membrane reactor length
gas
com
pone
nt fl
ow, N
m/h
r
H2 through membrane CH4CO H2CO2 H2O
00.05
0.1
0.150.2
0.25
0.30.35
0.4
0.45
0 0.2 0.4 0.6 0.8 1membrane reactor length
mol
e fr
actio
n in
feed
sid
e
CH4COH2CO2H2O
Gas component flow rates in the feed side of the membrane gasification reactor and hydrogen flow through the membrane
Gas compositions profiles in the feed side of the membrane gasification reactor
Feed: 30 atm, permeate: 1 atm,
T:1000C
Key Conclusions from Membrane Reactor Modeling> Membrane gasification reactor can improve
hydrogen production over the conventional coal gasification process by 30 ~ 50% for the same amount of coal feed.
> Membrane reactor performance determined by– Kinetics of reforming reaction– Equilibrium of shift reaction (high temperature)– Membrane hydrogen permeability
> Catalysts needed for reforming reaction
Future PlansMilestones for remainder of FY 2005
> Complete flowsheet simulation for hydrogen production based on
membrane gasifier processes. Identify one concept for addressing
chemical stability issues of perovskite membrane. (6/30/05)
> Complete technical and economical assessment of the membrane
gasifier technology (9/30/05)
Future Work
> Continue improving hydrogen flux– Reduce thickness, 5- 15 micron– Dual-phase membranes
> Permeation testing with simulated syngas
> Membrane scale-up
> Bench scale testing
Publications and Presentations
> Shain J. Doong, Estela Ong, Francis Lau, Arun C. Bose, and Ron Carty, “Direct Extraction of
Hydrogen from Coal Using a Membrane Reactor Within a Gasifier” paper presented at 21’st
International Pittsburgh Coal Conference, Osaka, Japan, September 2004
> Shain J. Doong, Francis Lau, Mike Roberts, and Estela Ong, “GTI’s Solid Fuel Gasification to
Hydrogen Program” paper presented at the 3rd Natural Gas Technology Conference, Orlando, FL,
February, 2005
Hydrogen Safety
The most significant hydrogen hazard associated with this project is:
> Hydrogen leakage
> Operation of high temperature and high pressure permeation unit
Hydrogen SafetyOur approach to deal with this hazard is:> Hazard assessment
– what-if/checklists, hazard and operability studies (HAZOP), failure mode and effects analyses (FMEA), fault tree analyses, and others.
> Risk management plan– identify approaches and actions required to mitigate and
minimize exposure to identified risks
> Communication plan– failure reporting and corrective actions, periodic revision
of all safety plans, training, emergency response plan development, and safety-related reporting to the sponsor
