Eltron Research & Development An Analysis of …...Eltron Research & Development An Analysis of...
Transcript of Eltron Research & Development An Analysis of …...Eltron Research & Development An Analysis of...
Eltron Research & Development
An Analysis of Dense Hydrogen Membranes as a Means of Producing a
CO2 Rich Stream Consistent with the CO2
Capture Requirements of a FutureGen Plant
Twenty-Third Annual InternationalPittsburgh Coal Conference
September 26, 2006
Paul J. Grimmer, Xiaobing Xie, Carl R. Evenson IV, Harold A. Wright – Eltron Research; Clive Brereton &
Warren Wolfs - NORAM
Eltron Research & Development
Slide 2
Coal, Hydrogen & FutureGen
� Coal is an abundant global energy resource. In the U.S. alone there are over 200 years’ reserves.
� Coal can be produced cheaply, much at less then $1/MMBTU ($70/bbl oil is $12.70/MMBTU).
� Coal has a multitude of contaminants.
� Coal contains very little H2. Energy from coal comes from C combusting to CO2. Compared to natural gas, coal causes over 3 times the CO2 emissions per MW (or mile driven etc.).
� The FutureGen initiative is to develop a 275 MW coal-fired power plant that also produces H2 and has zero (or near zero) emissions, including CO2.
Eltron Research & Development
Slide 3
Carbon Capture - Methods
� Post – Combustion
� Remove CO2 from combustion exhaust gases
� Pre-Combustion
� Convert fuel to CO2 and H2, remove CO2 before burning
� Oxy-Fuels
� Fire combustion with O2 instead of air
� Remove CO2 from exhaust gases
Eltron Research & Development
Slide 4
Post-Combustion CO2 Capture
� Remove CO2 from combustion gases
� Typically via amine absorption/regeneration
� Advantages
� Processes are established
� Can be applied to existing combustion systems
� Disadvantages
� Highest cost alternative
– Combustion exhaust (amine unit inlet) is typically < 15% CO2
– Combustion gas is typically at low pressure
� Recovered CO2 is at low pressure
Eltron Research & Development
Slide 5
Oxy-Fuels (with post-combustion CO2 Capture)
� Combustion with O2 instead of air
� Combustion exhaust is mainly CO2 and H2O
� Advantages
� Less exhaust gas to process (no N2)
� Separation is easier (mainly CO2/H2O separation)
� 30% cheaper than post-combustion method
� Disadvantages
� Generally requires new combustion system (higher combustion temperatures)
� Requires recycle of a portion of the exhaust gas for temperature control
� Requires O2 via cryogenic ASU (or perhaps membranes)
� Technology still in development
Eltron Research & Development
Slide 6
Pre-Combustion CO2 Capture
� Fuel conversion
� Feed is converted to synthesis gas
� Synthesis gas is “water-gas shifted” to a stream of CO2 and H2
� CO2 removed prior to H2 combustion.
� Advantages
� Can be 60% cheaper than post-combustion
� H2 has uses other than simple combustion
� CO2 can be captured at pressure
� Disadvantages
� Requires an ASU and a gasifier
� Methods in development (other than PSA)
Eltron Research & Development
Slide 7
Pre-Combustion Separation Methods
� Pressure Swing Adsorption
� Micro-Scale Filtration
� Amine Absorption
� Dense Membranes
� Ceramic
� Metallic
� Composite (e.g. Cermets)
Eltron Research & Development
Slide 8
Pressure Swing Adsorption
� Advantages
� Well-established commercially especially in natural gas systems and refineries
� Feed impurities largely stay with the raffinate (CO2 stream)
� Can produce fairly high purity H2
� Disadvantages
� Raffinate is at low pressure (typically near atmospheric)
– Essentially limited to one stage of WGS (less CO conversion & H2 recovery)
– Additional costs to compress the CO2 for sequestration
� Only 80-90% of H2 is recovered (remainder in raffinate)
� Only 1 stage of WGS (low pressure raffinate)
� Higher purity H2 product requires more energy (more freq. switching) and more H2 lost in CO2 raffinate
� Mechanically more complex – switching beds
� Higher energy usage than filters / membranes
� Higher capital cost
Eltron Research & Development
Slide 9
Micro-Porous Membranes
� Advantages
� Simple, no moving parts
� Retentate at high pressure
� Multiple stages of WGS possible
� Disadvantages
� Separation quality questionable
– CO2 in H2 product, H2 in raffinate
� H2 product at relatively low pressure
� Still in development
– Cost
– Fabricability
– Contaminant and steam tolerance
Eltron Research & Development
Slide 10
Dense Membranes
� Advantages
� Simple, no moving parts
� Pure H2 product
� Raffinate (CO2) at high pressure
� Enables multiples WGS stages
� Low cost (maybe)
� Disadvantages
� Low flux – large membrane area required
� Ceramic
– High operating temperatures (above WGS)
– Sealing between ceramic and metal
– Low allowable ∆P (mechanical strength)
� Metallic
– Low outlet H2 pressure (limited by embrittlement)
– Cost - Palladium (most common) is very expensive
– Contaminants (sulfur causes Pd4S)
� Still in development
Conceptual design of a commercial membrane unit capable of separating 25 tons per day of hydrogen. Sizing is based upon syngas at 1000 psig (69 bar), 450°C, 50 vol.% H2 in feed.
W ater-gas shift mixture entrance
Concentrated CO 2 exhaust
Closed end o f tubes
M embrane tubes
Hydrogenexit
Eltron Research & Development
Slide 11
Hydrogen Transport Across Eltron’s Membrane
H-HH-H
H-H
H-H
Layers ofHydrogen
DissociationCatalyst
HydrogenTransport
MembraneMaterial
H-HH H H H
H HH H
H
HydrogenDissociation
Diffusion of Hydrogen inDissociatedForm
Recombination and
Desorption of H2
HH
H-H
H-H
Eltron Research & Development
Slide 12
Eltron’s Layered Membrane vs. Thin Films
� Leaks – pinhole & other
� Syn gas comes through leaks in thin film
� Gas stops at the bulk membrane layer in Eltron’s HTM
� Performance
� Eltron’s HTM has very thin catalyst layers for higher flux
� Cost
� Catalyst layers on Eltron HTM are 0.1 micron or less
� Thin films are 5-10 microns thick
Eltron Research & Development
Slide 13
Planar Design (SOFCo)
SOFCo Planar Design(DE-FC26-OINT41145)
�Wafer panel length 2 m (6.55 ft)
�159 stacks
�590 tons per day of hydrogen (234 MMSCFD)
�FutureGen: Need to evaluate merits of tubular versus planar
Eltron Research & Development
Slide 14
Formed/Rolled Heads
Custom Flanges
Feed Gas
Retentate
High temp. valves
Packed
Unions
Purge/Sweep
Permeate
Distribution Header,
Anchored Membrane
Distribution Header,
Floating Press. Relief
Vent
Permeate
Figure 6: Low-Pressure Design
Tubular Designs (NORAM)
Eltron Research & Development
Slide 15
500N/AN/AN/APermeate Pressure (psi)
0.9>531Stability/Durability (years)
>99.99999.9999.595Hydrogen Purity (%)
YesYesYesYesCarbon Monoxide Tolerance
1,000800-1000400100∆P Operating Capability (psi)
<200<2505001000System Cost ($/ft2)
20 (early)202N/AS Tolerance (ppmv)
320-440250-500300-600400-700Operating Temperature (oC)
16015010050Flux (sccm/cm2/100 psi ∆∆∆∆P)
Current Eltron
Membrane
2015
Target
2010
Target
2005 TargetPerformance
Criteria
Progress Towards DOE FutureGen Targets
Eltron Research & Development
Slide 16
Water-Gas Shift Consideration
� Synthesis Gas (not just from coal) contains CO2, H2, CO and H2O
� Water-Gas Shift Reaction
CO + H2O ↔ CO2 + H2
� At equilibrium, outlet CO is well under 4%
� By using one or more WGS reactors in conjunction with a CO2/H2 separation system, almost all of the CO can be converted to more CO2 and H2
� WGS is mildly exothermic (generates heat)
Eltron Research & Development
Slide 17
Role of Hydrogen Separation Membranesin CO2 Sequestration
2352mvm.dsf
ParticulateRemovalSystem
CatalystGuardBeds
Water-Gas Shift
Reactor
40% H2 +CO2 + H2O
340-440°C1000 psi
H2 + CO
320-440°C1000 psi
Synthetic FuelsPetroleum RefiningFuel Cells
Electricity
H2O
Compress H2
435 psi
Steam320°C
1000 psi
H2 + CO
320°C1000 psi
Electricity
H2O
H2O
H2 + COSynthesis Gas
H2 + CO
1040°C1000 psi
SteamTurbine
1000 psiCO2
H2O
Slag Oil + GasRecovery
HeatExchanger
320°C1000 psi
320°C1000 psi
Steam
Oxygen
H2
CoalGasifier
>1040°C1000 psi
HydrogenTurbine
CoalSlurry
Oxygen
HydrogenSeparation
Unit
AirAirSeparation
Unit
N2
<400 psi
CO2 Sequestration Condense H2OCompress CO2 2700 psiCO2 Pipelines
Eltron Research & Development
Slide 18
WGS WGS WGS
H2
H2
H2 H2 H2 H2
H2 H2
H2 H2
Compr
Compr
5 psig
60 psig
200 psig
Compr
-10 psig
Steam
H2 to Fuel or Export
Synthesis Gas
Simplified FlowsheetStaged WGS / HTM System
Maximum H and CO Production22
CO2 to Sequestration
> 96% Recovery
1,000 psig300°C
950 psig400°C> 96% CO (ex H O)22
HTM1
HTM2
HTM3
HTM1
HTM2
HTM3
HTM1
HTM2
HTM3
HTMV
Eltron Research & Development
Slide 19
Process Issues Being Worked
� Contaminant handling
� Rejected on membrane surface
� Removal upstream of WGS/HTM system
� Integrated vs. staged WGS/HTM
� Stage optimization
� Recovery per stage (area vs. compression)
� Membrane configuration
� Tubular vs. planar
� Commercial scale catalyst application
� Residual H2 Handling
� Maximum recovery vs. Hi-P combustion
� Cost Comparison vs. PSA, post-combustion capture etc.
Eltron Research & Development
Slide 20
� In their 2005 book, the Carbon Capture Project team (BP, Chevron, Shell, Statoil, Norsk Hydro, ENI, Suncor and EnCana) stated that “the team believes that membrane reactors for hydrogen production have the potential for significant cost reduction and gave this technology its top priority.”
� Baseline – Post-combustion capture
� PSA – Estimated 30% cost reduction
� Dense membranes – 60% cost reduction
– (Prior to Eltron permeate pressure discovery)
Eltron Research & Development
Slide 21
Other Considerations
� HTM enables purity H2 production with CO2 capture
� Eltron believes it will be best-in-class for either.
� It doesn’t care whether the synthesis gas feedstock is from coal, biomass, petroleum coke, distillates, LPG, natural gas etc.
� Given the relative instability of gasifiers and the range of contaminants in coal, FutureGen is likely the most difficult application of HTM.
� Eltron is evaluating a number of other applications other than H2 separation from syn gas including dehydrogenation (on the inlet side) and other reactions involving H2 on the permeate side.
Eltron Research & Development
Slide 22
(Clever) Application in an IGCC Power Plant
Please see presentation by Bill Rollins of NovelEdge Technologies in session 49 of this conference titled “High Efficiency Coal Plant that Meets the DOE 2002 Goal”