Transcript CENTER FOR INNOVATION IN CARBON CAPTURE AND …

Nottingham Fuel
& Energy Centre
Novel Capture Methods (sorbents,
membranes and enzymes)
Trevor C. Drage and Colin E. Snape
School of Chemical and Environmental Engineering,
University of Nottingham,
University Park, Nottingham NG7 2RD
[email protected]
International workshop on “Power Generation and Carbon
Capture and Storage in India”
Delhi 2008
Alternative capture
technologies
Why?
Nottingham Fuel
& Energy Centre
• Physical and
chemical solvent
systems leading
technologies for pre
and post combustion
capture respectively.
• Current CO2 capture technologies consume power and
can significantly increase the cost of electricity.
• Need for the development of alternative low cost
technologies to provide a more effective route for the
capture and storage of CO2 on a global scale.
The Challenge
Nottingham Fuel
& Energy Centre
Conditions for Capture
Pre-combustion
capture (after
water gas shift)a
Post-combustion
captureb
CO2
35.5 %
15 – 16 %
H2 O
0.2 %
5–7%
H2
61.5 %
-
O2
-
3–4%
CO
1.1 %
20 ppm
N2
0.25 %
70 – 75 %
SOx
-
< 800 ppm
NOx
-
500 ppm
H2 S
1.1%
-
40 °C
50 – 75 °C
50 – 60 bar
1 bar
Gas composition
Conditions
Temperature
Pressure
aLinde
Rectisol, 7th European Gasification Conference; bPennline (2000), Photochemical removal of mercury from flue gas, NETL
Alternative capture
technologies
Nottingham Fuel
& Energy Centre
• Range of technologies
being developed
• Technologies to
demonstrate clear
competitive edge
• If plant is build as
“capture ready”
technologies can be
integrated
• Technologies need to
overcome challenges of
other acids gases, SOx
and NOx etc
• Rapid development
required
• Risk that technologies will
not scale up
Source: Figueroa et al. 2008 – Int. J. Greenhouse Gas Control 2;9-20.
Pre-combustion capture
Sorbent systems
Nottingham Fuel
& Energy Centre
• High temperature sorbents – Metal oxides(1,2), Hydrotalcite-like compounds and
carbonate / silicate(3) compounds.
• Operate at high temp – capture combined with the water gas shift reaction (wgs) /
gasification, reduced CAPEX and increased thermal efficiency + can promote wgs
reaction (Li4SiO4).
• Developing stable, attrition resistant, regenerable (low energy penalty), H2S resistant
material key
Heating cycles 323 – 1273 K
CO2 capture
Cooling + separate
process avoided.
Source: Feng et al.,
(1)
Feng et al., 2007, Energy & Fuels, 21:426-434
Siriwardane et al., 2007, Prep. Pap. Am. Chem. Soc.,
Div. Fuel Chem. 52(2) 5.
3 Li et al., (RTI International), 22nd + 23rd International
Pittsburgh Coal Conference.
1
2
Overall reaction:
C + H20 → H2 + CO
CO + H2O → CO2 + H2
CAM + CO2 → CAM – CO2
(steam gasification)
(wgs)
(CO2 adsorption)
Pre-combustion capture
Sorbent systems
Nottingham Fuel
& Energy Centre
Low temperature sorbents – Microporous materials (activated carbons(1),
MOFs) after wgs reaction, direct replacement of Rectisol / Selexsol
Potentially regenerate CO2 at high pressure (TSA) – saving compression costs.
40 bar 30 C
35.00
-1
CO2 adsorption (mmol g )
7.0
30.00
6.0
25.00
5.0
20.00
4.0
15.00
3.0
10.00
2.0
5.00
1.0
0.0
400
600
800
1000
1200
1400
1600
1800
0.00
2000
SBET (m2g-1)
Drage et al., Fuel (in press) / Research Fund for Coal and Steel
(CT-2006-00003)
2 DTI Cleaner coal technology programme (project 406)
1
CO2 adsorption (wt.%)
8.0
•Feasibility study(2) based on a
conservative adsorption capacity of
12 wt.%
•Fixed bed adsorption with pressure
swing regeneration potential
economic benefits over physical
solvent systems
•Ability to produce CO2 at relatively
high pressure, (i.e 10 bar) would
have a significant impact in
reducing CO2 compressor cost
•If higher (20+%) cyclic adsorption
capacities can be achieved, TSA
cycles can potentially be employed
leading to significant benefits, CO2
recovered at 30 – 40 bar.
Pre-Combustion Capture
Membranes
Nottingham Fuel
& Energy Centre
• High temperature and CO2 partial pressure operation
• Advantages:
 Single stage separation – one-step process
 Can promote reaction by shifting equilibrium (lower reaction temp)
 CO2 retained at relatively high pressure
• Key to efficient operation:
 Permeance - determines membrane area required
 Selectivity - influences % recovery of H2
• Range of membranes explored
• Inorganic – e.g. silica / alumina / zeolites / palladium
 Improvements by surface chemistry modification of silica / alumina
 Palladium high H2 selectivity + permeability (300 – 600 C)
• Organic Polymers
 Supported Liquid Membrane – ionic liquids(1)
Source (1) Ilconich et al., 2007 J. Memb Sci (In Press)
(2)
IPCC Special report on CCS 2005
Post-combustion capture
Membranes
Nottingham Fuel
& Energy Centre
• Polymeric Gas Separation Membranes
• Used in CO2 removal from natural gas – low CO2 partial pressure leads to low driving
force for gas separation
• Illusive balance between permeability and selectivity
• Hybrid membrane systems
• Membrane acts as high surface area contactor between gas stream and solvent
• Avoids operational problems of conventional adsorption (flooding, foaming,
channelling and entrainment), impurities blocked from reaching solvent
• Reduced plant size, CAPEX, gas / liquid flow rates flexible
• Many types of membrane explored – e.g. Facilitated transport membranes
• Membrane is crucial – hydrophobic, permeable, physical strength
• Challenges – large scale manufacture, avoiding imperfections, cost
Source: Franco et al., 2006 – GHGT-8.
Post-combustion capture
Adsorbent Development
Nottingham Fuel
& Energy Centre
CO2 uptake (wt %)
8
Flue gas
Temperature
Amine-CO2 chemical adsorption
CO2 + 2R2NH  R2NH + R2NCOO<1>
CO2 + 2R3N  R4N+ + R2NCOO<2>
CO2 + H2O +R2NH  HCO3- + R2NH2+ <3>
10
Maximising sorption
capacity key
3 – 6 mmol g-1 required
to make competitive
12
6
Supported PEI
4
N-enriched active carbon(1,2)
Physical adsrobent
2
0
20
30
40
50
60
70
80
90
100
Gray et al.,(3)
Temperature oC
• Many groups developing solid sorbents for CO2 by developing porous substrates (e.g MCM-41,
SBA-15) enhanced with basic nitrogen groups (Penn State, NETL, Monash, Dartford,
Nottingham etc..)
• Critical to operation is:
 Adsorption capacity
 Energy requirement for regeneration
Drage, T.C., Arenillas, A., Smith, K., Pevida, C., Pippo, S., and Snape, C.E.
(2007) Fuel, 86, 22-31
 Sorbent lifetime, attrition resistance
Arenillas, A., Drage, T.C., Smith, K.M, and Snape C.E. (2005). JAAP, 74, 298306.
 Cost
Gray et al (2008) J. Greenhouse Gas Control, 2:3-8.
(1)
(2)
(3)
Post-combustion capture
economic studies
Nottingham Fuel
& Energy Centre
NETL study:
based on:
• 90 % CO2 removal
• Pressure drop < 6 psi
• Use of enriched amine SBA-15 substrate
• Adsorption offers potential cost saving over
MEA scrubber
• Fixed bed not viable due to large footprint
Nottingham study:
• Proposed novel moving bed design (Carbon
Trust Funded)
• Minimising temperature difference between
adsorption and regeneration key(1)
• System has potential to reduce capture cost
• Current research looking to scale-up to Kg
operation
1T.C.
Source: Tarka et al., 2006, Prep. Pap.-Am. Chem. Soc., Div. Fuel. Chem.
Drage, A. Arenillas, K.M. Smith, and C.E. Snape. Microporous and Mesoporous Materials – In Press
51(1), 104.
Enzymes
Nottingham Fuel
& Energy Centre
Fast reaction rate +
Low regeneration energy
Fast reaction + low regeneration energy.
Enzyme used by higher plants and mammals
CO2 + H2O → HCO3- + H+
<1>
+
HCO3 + H → H2CO3 → CO2 + H2O
<2>
Reactions catalysed by carbonic anhydrase
Source: Carbozyme Inc – Proceeding of 8th International Conference on
Greenhouse Gas Control Technologies + refs within.
Acknowledgements
Nottingham Fuel
& Energy Centre
Thank the following for invite:
•
•
•
•
Integrated Research and Action for Development (IRADe)
Department for Environment Food and Rural Affairs (DEFRA)
British High Commission (BHC)
Ministry of Science and Technology – Government of India
Engineering and Physical Science Research Council, UK (EPSRC) –
Advanced Research Fellowship to TD (EP-543203/1) for funding
continued research in CO2 sorbents