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Pre-combustion capture Professor Raphael Idem Clean Energy Technologies Research Institute University of Regina
IEAGHG Summer School 2015 University of Regina Saskatchewan, CANADA 18-22 July 2016
Faculty of Engineering & Applied Science
Modified from the Presentation of Professor Dianne Wiley UNSW, Australia IEAGHG Summer School 2015
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DEFINITIONS
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1. Combustion
• Burning of fuel and oxidant to produce heat and/or work – fuel can be solid, liquid or gas – fuel can be fossil fuel or biomass (alone or used together)
• fuel + oxygen/air (O2) → carbon dioxide (CO2) + water (H2O) • + other gases (N2, SOx, NOx, CO) • + ash • + HEAT/ENERGY
Reaction
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2. Gasification • Partial oxidation, oxidation and reforming of fuel and oxidant (with
limited O2) to produce syngas and heat – fuel can be solid, liquid or gas – fuel can be fossil fuel or biomass (alone or co-fired)
• fuel + oxygen/air (O2) + steam (H2O) → • carbon monoxide (CO) + hydrogen (H2) • + methane (CH4) + carbon dioxide (CO2) • + water (H2O) • + other gases (H2S, COS, NH3, HCN) • + ash + slag • + HEAT Syngas can be burnt or reacted further
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Reaction
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Gasification reactions
Source: www.netl.doe.gov/research/coal/energy-systems/gasification/gasifipedia/reaction-transformations
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Gasification for chemicals production
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Source: www.netl.doe.gov/technologies/coalpower/gasification/gasifipedia/6-apps/6-5-2_coal-to-derivative.html
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3. Reforming using CO2 Reformation Reactions
Hydrogen, Syngas from Bioenergy Solution gas
Pre-Combustion Capture
Gasifier
Electricity Generation
Water gas shift converter
CO2 capture process
Syn Gas H2 + CO
Water Gas
H2 + CO2 CO2
H2
Coal
Air/O2
Further purification and Compression for transportation,
storage and further use
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Pre-combustion capture • Capture CO2 for storage or reuse • Use water-gas shift reactor to maximize H2 production
– CO + H2O CO2 + H2
• Use H2
– combust in a combined cycle gas turbine plant to produce electricity – sell for distributed energy production – provide to fuel cell
• Similar processes apply to H2 production using – SMR (steam methane reforming) – ATR (autothermal reforming)
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Pre-combustion capture
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Example of IGCC power plant with capture
Source: Vatenfall
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Solvent absorption capture
• >> Animation of absorption process • www.co2crc.com.au/imagelibrary2/vid_ab
sorp_desorp.html
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Solvents for pre-combustion capture • Physical solvents
– Rectisol (methanol) • Lurgi and Linde, Germany • Lotepro, USA
– Purisol (N-methyl-2-pyrolidone: NMP) • Lurgi, Germany
– Selexol (dimethyl ethers of polyethyleneglycol: DMPEG) • Union Carbide, USA
• Chemical solvents – MDEA (Methyl diethanolamine (N-methyl-diethanolamine))
• Union Carbide, USA
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Example of Coal gasification: Beulah, North Dakota, USA
• Dakota Gasification Company’s Great Plains synfuels plant • Gasification of lignite coal: 55 tonnes/h in14 Lurgi Mark IV
gasifiers operating at 1200°C – produces syngas and a range of chemical products
• synthetic natural gas • ammonium sulfate • fertilizers • phenol • cresylic acid • liquid nitrogen • methanol • naphtha, • krypton • xenon
Source: Dakota Gasification Company
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Dakota gasification plant: CO2 removal • CO2 separated using solvent absorption
– Rectisol process (methanol) – pressure change regeneration
• 3 Mtpa CO2 – 96% pure, dry, oxygen and nitrogen free – transported 205 miles by pipeline to Saskatchewan, Canada – used for EOR
Source: Dakota Gasification Company
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Map of transportation of CO2 from North Dakota to Weyburn, Saskatchewan
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Physical absorption systems
http://netl.doe.gov/research/coal/energy-systems/gasification/gasifipedia/selexol Selexol
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Selexol
Comments
• The solvent is not reactive • Pressure is needed to help the absorption process • Pressure release favors regeneration • Smaller amount of external heat is required
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IGCC: Kemper County, Mississippi, USA
• New 582 MWnet IGCC using TRIG™ technology air blown gasification
Selexol for H2S and CO2 removal
• Mississippi lignite coal • Capture
– 3.5 Mtpa CO2
– 65% capture rate – used for on-shore EOR – operational 2016
Source: Mississippi Power
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Advantages of pre-combustion solvent capture
• High CO2 concentration (for oxygen blown gasification) – large driving force for separation – easy separation requirements
• High flow-rate – large economies of scale
• Gasification is an established industrial process
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Challenges for pre-combustion solvent capture • High temperature (unless pre-cooled)
– increases materials degradation • High H2 concentration
– causes materials embrittlement • High flow-rate
– increases equipment size • High capital cost of gasification plant • Limited commercial-scale energy ~ 250 MW (more recently
437 MW) – expensive compared to conventional supercritical plants
• Difficult to retrofit to existing plant
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2nd & 3rd generation pre-combustion capture technologies
• Some technologies under investigation VSA or PSA (Vacuum or Pressure Swing Adsorption) SEWGS (Sorbent Enhanced Water Gas Shift) Gas separation membranes Low temperature separation IGFC (Integrated Coal Gasification Fuel Cell)
• Major focus on combined CO shift and CO2 capture Reduce capital cost Reduce energy penalty Reduce complexity
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Pressure swing adsorption
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http://www.essentialchemicalindustry.org/chemicals/oxygen.html http://www.foxolution.co.za/psa-technology.php
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Comments
• Uses pressure to get one component to adsorb on an adsorbent relative to the other component
• The other component is produced as a relatively pure component
• The adsorbed component is then desorbed from the adsorbent by releasing the pressure
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Port Arthur: VSA and PSA following SMR • CO2 separation with VSA followed by PSA
– concentrate CO2 from 10-20% to >97% – 90% recovery
• 1 Mtpa CO2 – used for EOR in Texas – first stage operational in 2012
Source: netl.doe.gov/File%20Library/factsheets/project/FE0002381.pdf
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Sorbent Enhanced Water Gas Shift Process
Refo
rmin
g &
Ca
rbon
atio
n
Rege
nera
tion
/ Ca
lcin
atio
n
Regeneration Gas
CO2-loaded Sorbent
Regenerated Sorbent
Hydrogen Regeneration Gas + CO2
Natural Gas & Steam
Sorbent Purge
Sorbent Makeup
Regeneration Energy
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Advantages of SEWGS • Process intensification
– simultaneous production of H2 and capture of CO2 with a combined sorbent catalyst
– eliminate shift reactor • Lower operating temperature
– reduce energy requirements – replace high temperature, high alloy steels in reformer – reduction or elimination of carbon deposition in reformer
• Potential cost reduction
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Challenges for SEWGS
• Issues with sorbent catalyst – decay in activity – sintering – attrition and fragmentation – control of competing reactions
• Ash fouling in the calciner 0 1 2 3 4 5 6 7 8 9 10
10
20
30
40
50
60
70
80
90
100
C N [%
]
Cycle no. [-]
0 1 2 3 4 5 6 7 8 9 10
10
20
30
40
50
60
70
g-CO
2 / g
-sor
bent
[%]
Havelock, 10% steamLongcliffe, 10% steamCadomin, 10% steamPurbeck, 10% steam
1 cycle 30 cycles
Source: Donat et al. (2012) ‘Influence of high-temperature steam on the reactivity of CaO Sorbent for CO2 capture’, Environ Sci Technol, 46: 1262-1269
Source: Abanades & Alvarez (2003) ‘Conversion limits in the reaction of CO2 with lime’, Energy Fuels, 17: 308-315
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Pre-combustion membranes • Process options
– membrane: H2 selective (metallic, porous inorganic, carbon, molecular sieve) or CO2 selective (polymeric)
– placement: before/between/within shift, during CO2 compression
• Advantages – compact and modular with no moving parts – low maintenance and highly reliable
• Challenges – high recovery of H2 – delivery of product at high pressure – membrane lifetime – scale-up
Source: ‘Integration of H2 separation membranes with CO2 capture and compression’ (2009) DOE/NETL-401/113009
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Low temperature separation
• Process conditions: -60°C • Advantages
– produces liquid CO2
– potentially low energy and cost – cooling can be provided by expanding feed gas – low temperature separation is a well established
technology • Challenges
– high recovery needs high pressure or hybrid process (e.g. with solvent capture)
– no pilot or demonstration yet
Source: Berstad et al (2013) Energy Procedia 37: 2204–2211
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Integrated Coal Gasification Fuel Cell • Advantages
– some fuel cells have high efficiency and use H2
– inherent CO2 capture if anode and cathode gases are separate
• Challenges – SOFC stack degradation – raise conversion efficiency
• reduce cell over-potential • higher methane content syngas
– full integration of SOFC stack to IGCC with capture not tested
Source: Keairns & Newby (2010) ‘Integrated gasification fuel cell (IGFC) systems’, 11th Annual SECA Workshop, Pittsburgh
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Technology status
Technology TRL Potential to reduce LCOE of capture
IGCC with selexol 9 +100% to 130% of baseline
H2 separation membrane with warm gas clean-up
5 -25%
SEWGS 5 -30%
Low temperature separation 2 -30%
Low temperature separation with CO2 recycle
2 -50%
IGFC 4-6 -70% to 95%
Adapted from: IEAGHG (2014) ‘Assessment of emerging CO2 capture technologies and their potential to reduce costs’ Report 2014/TR4
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Useful resources
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