Presentation given by Richard T. J. Porter from ETII, University of Leeds, on "CO2QUEST Typical Impurities in Captured CO2 Streams" at the EC FP7 Projects: Leading the way in CCS implementation event, London, 14-15 April 2014

1. 1
CO2QUEST
Typical Impurities in Captured CO2 Streams
Richard T. J. Porter
ETII, University of Leeds
http://etii.leeds.ac.uk
EC FP7 Projects: Leading the way in CCS Implementation
14 – 15 April 2014, UCL

2. Background
2CO2QUEST
 CO2QUEST project:
• Techno-economic Assessment of CO2 QUality Effect on its Storage
and Transport
 First Task:
• Define the range and level of impurities expected in CO2 product
gas streams from different capture technologies and other CO2
intensive industries.

3. Overview
3CO2QUEST
 Analysis of the range and level of impurities present in CO2 streams
captured from power sector using:
• Oxyfuel combustion capture
• Pre-combustion capture
• Post-combustion capture
 Assessment of the different parameters affecting the CO2 mixture
composition:
• Power plant mode of operation
• Impurity removal technology selection
 Range and level of impurities from non-power industrial sector
 Information used as the basis of investigation in other work packages

4. Classes of CO2 Impurities by Origin
4CO2QUEST
Coal/biomass oxidation products
Complete Partial
H2O, SOx, NOx, HCl, HF CO, H2S, COS, NH3, HCN
Volatiles Biomass alkali metals
H2, CH4, C2H6, C3+ KCl, NaCl, K2SO4, KOH etc.
Trace metals Particulates
Hg (HgCl2), Pb, Se, As etc. Ash, PAH/soot
Oxidant / air ingress Process fluids
O2, N2, Ar Glycol, MEA, Selexol, NH3

5. Oxyfuel Combustion Capture Process
5CO2QUEST
SCR: Selective Catalytic Reduction reactor (deNOx)
ESP: Electrostatic Precipitator
FGD: Flue Gas Desulfurization
Toftegaard et al. Progress in Energy and Combustion Science 36 (2010) 581-625.

6. Raw Oxyfuel CO2 Cooling and Compression to 30 bar
6CO2QUEST
Flue Gas
Direct Contact
Water Scrubbing
Packed Tower
Condensed H2O
Soluble gases SO3/HCl
(to coal mill)
(15 bar)
(30 bar)
To Drying and
Purification System
Raw Flue Gas
@ 35°C, 1.02 bar
mol%
CO2 71.5
N2 14.3
O2 5.9
Ar 2.3
SO2 0.4
NO 0.04
H2O 5.6
Heat of compression
recovered for boiler
feedwater heating
condensate preheating
in boiler steam system
Final coolers
using cooling water

7. Cold
exchanger (-55ºC)
Flash
separators
Oxyfuel CO2 inerts removal and compression to 110 bar
7CO2QUEST
Dual-bed
dryer
30 bar raw
CO2
Multi-stream
heat-exchangers
Warm
exchanger
Flue gas
vent
CO2
product
Power recovery
turbine
 Double flash case
Adiabatic
throttles
CO2 product
@ 43°C, 110 bar
mol%
CO2 95.84
N2 2.03
O2 1.05
Ar 0.61
SO2 0.45
NO 0.013
H2O 0
Oxy Combustion Processes for CO2 Capture from Power Plant, IEA Greenhouse
R&D Programme, Report No. 2005/9.

8. Oxyfuel CO2 inerts removal and compression to 110 bar
8CO2QUEST
 Distillation case
Ten plate
column
unit
30 bar raw
CO2
-27ºC
Heat exchanger
-54ºC
Flue gas
vent
CO2
product
-10ºC
CO2 product
@ 2.7°C, 110 bar
CO2 99.3 %
N2 0.2 %
O2 0.4 %
Ar 0.1 %
SO2 37 ppm
NO 32 ppm
H2O -
NO2 1 ppm
(calculated)

9. Oxyfuel “Sour Compression” Process
9CO2QUEST
 Air products patented variation on the lead chamber process
NO + ½O2  NO2 (1)
NO2 + SO2  NO + SO3 (2)
SO3 + H2O  H2SO4 (3)
2NO2 + H2O  HNO2 + HNO3 (4)
3HNO2  HNO3 + NO + H2O (5)
 Potential to remove Hg by reaction with HNO3

10. Oxyfuel “Sour Compression” Process
10CO2QUEST
(To coal mill)
Raw flue gas
Direct Contact
water scrubbing
packed tower
Water
To Drying and
Purification system
Additional contacting
columns
 ~90% NOx and all SO2 removed prior to inerts removal
(15 bar)
(30 bar)

11. Oxyfuel Process Parameters Affecting CO2 Purity
11CO2QUEST
 ASU: Oxidant composition (95 – 99 O2 vol%), ASU power requirement
(kWh/ton O2)
 Fuel: Proximate/Ultimate analysis, ash analysis, trace elements
 Boiler: Excess oxidant, Air leakage, Furnace temperature, SO2/SO3
conversion, S retention in ash, Burnout, In-furnace NOx control config.
 SCR: NOx removal efficiency, Ammonia slip
 ESP: Particulate removal efficiency
 FGD: SOx removal efficiency, Particulate removal efficiency, Chloride
removal efficiency
 CO2 capture: Flue gas recycle ratio, CO2 compression and purification
config., CO2 unit purification energy (kWh/ton CO2)

12. Oxyfuel CO2 Impurities (pulverised coal)
12CO2QUEST
Raw / dehumidified Double flashing Distillation
COORAL Wilkinson Pipitone IEAGHG Air *
products
Pipitone COORAL Pipitone
CO2 vol% 85.0 77.19 74.8 95.84 96.3 96.7 99.94 99.3
O2 vol% 4.70 3.21 6.0 1.05 1.1 1.2 0.01 0.4
N2 vol% 5.80 15.49 16.6 2.03 2.0 1.6 0.01 0.2
Ar vol% 4.47 4.03 2.3 0.61 0.6 0.4 0.01 0.1
NOX ppm 100 - 709 130 0 150 100 33
SO2 ppm 50 800 702 4500 0 36 50 37
SO3 ppm 20 - - - - - 20 -
H2O ppm 100 0 1000 0 0 0 100 0
CO ppm 50 - - - - - 50 -
* Includes sour compression step prior to inerts removal

13. Pre-combustion (IGCC) Capture Process
13CO2QUEST
Air
Separation
Unit
Gasifier
Unit
Coal
Water
Gas Shift
Reactor
Sulphur
Removal
Unit
(Selexol)
CO2
Absorber
(Selexol)
Air
Comp.
Gas
Turbine
Combustor
Slag to
Landfill
To Sulphur Recovery To Geological Storage
Stack
Heat
Exchangers
Air
N2
Steam
Turbine
Solid Fuel
Oxidant
Syngas
Waste/Byproduct
Combustion Product
Water/Steam Cycle

14. Pre-combustion (IGCC) Process Parameters Affecting
CO2 Purity
14CO2QUEST
 ASU: Oxidant composition (95 – 99 vol%), ASU power requirement
(kWh/ton O2)
 Fuel: Proximate/Ultimate analysis, ash analysis, trace elements
 Gasifier area: Gasifier T, p and λ, water/steam input, ash carry-over, S
loss in solids, particulate removal efficiency
 Sulfur Removal: COS/H2S shift reactor conversion, COS/H2S removal
efficiency, solvent selection
 CO2 capture: CO/CO2 conversion efficiency, CO2 removal efficiency
(power requirement), solvent selection

15. Pre-combustion (IGCC) CO2 Impurities (pulverised coal)
15CO2QUEST
COORAL Selexol
EC report
Linde
Rectisol®
Sour SEWGS*
ECN EDGAR
French CO2
Club †
CO2 vol% 98.0 98.1 95-98.5 > 99
N2 vol% < 0.9 0.0195 < 1 < 1 0.0195
H2 vol% < 1 1.5 0.002 < 1 2.4
Ar ppmv < 300 178 150 < 1 1000
H2O ppmv 10 – 600 378 0.1 – 10 500 5.07
H2S/COS ppmv < 100 1700 0.2 – 20 1 – 5000 5968
CH4 ppmv 100 112 100 < 1
CO ppmv 400 1300 400 < 1 1667
CH3OH ppm 200 - 20 – 200
Ash ppm 1.2
NH3 ppmv 38
Cl ppmv 17.5
Hg ppbv 0.068 1.1
As ppmv 0.0033 0.01
Se ppmv 0.01 0.017
* Sorption Enhanced Water Gas Shift
† Average values from 1-6 literature sources
ppm French
CO2 Club
NO 400
SO2 25
Ni 0.009
Pb 0.0045
Benzene 0.014
Napthalene 0.0008

16. Post-combustion Capture Process
16CO2QUEST

17. Post-combustion Process Parameters Affecting CO2
Purity
17CO2QUEST
 Fuel: Proximate/Ultimate analysis, ash analysis, trace elements
 Boiler: Excess air, Air leakage, Furnace temperature, SO2/SO3
conversion, S retention in ash, Burnout, In-furnace NOx control config.
 SCR: NOx removal efficiency, Ammonia slip
 ESP: Particulate removal efficiency
 FGD: SOx removal efficiency, Particulate removal efficiency, Chloride
removal efficiency
 CO2 capture: Solvent selection, Direct contact cooler use, SO2 polisher
use, SOX, NO2, HCl, particulate removal efficiency; CO2 capture rates (85
– 95%), flue gas temp (30 – 50 ºC), Amine recycle rates, Stripper
temperature / efficiency.

18. Post-combustion CO2 Impurities (pulverised coal)
18CO2QUEST
COORAL
Amine
PC plant
EC report
MEA
PC plant
EC report
MEA
Cement Plant
EC report
MEA
Refinery Stack
French CO2
Club †
CO2 vol% 99.8 99.7 99.8 99.6 N.I.
N2 vol% 0.045 (+Ar) 0.18 0.0893 0.29 N.I.
CO ppmv 1.2 1.2 10
Ar ppmv 22 11 11 210
H2O ppmv 100 640 640 640 N.I.
NOx ppmv 20 1.5 (NO2) 0.86 (NO2) 2.5 (NO2) 38.8
SOx ppmv 10 < 1 (SO2) < 0.1 (SO2) 1.3 (SO2) 67.1 (SO2)
CO ppmv 10 1.2 1.2 10
O2 ppmv 150 61 35 35 N.I.
Cl ppmv 0.85 0.41 0.41
Ash ppm 11.5 5.7 -
Hg ppmv 0.00069 0.00073 0.0028
As ppmv 0.0055 0.0029 0.0022
Se ppmv 0.017 0.0088 0.0122
† Average values from 1-4 literature sources
ppm French
CO2 Club
Mn 0.0309
Ni 0.002
Pb 0.0011
Benzene 0.019
Napthalene 0.0012

19. CO2 intensive industries
19CO2QUEST
 Iron, Steel and Metallurgical Coke Production
• Blast furnace gas roughly 60% N2, 28% CO and 12% CO2 (vol.)
• Apply post-combustion capture
 Cement production
• Flue gas is 15-30 vol% CO2 – higher than power plants
• Apply post-combustion capture
 Hydrogen and ammonia production
• Application of solid-fuel gasification or natural-gas reforming
• Parallels can be drawn with pre-combustion CO2 stream
 Natural gas processing using amines
 Lime production
• Calcination of limestone or dolomite in rotary kiln
• Exhaust gas contains 50 vol% CO2, trace metals and HCl
• Apply post combustion capture

20. Non-power sector CO2 stream composition using post-
combustion capture
20CO2QUEST
MEA
Refinery
MEA Cement
Plant
Cement
Kiln
Coke
Production
Lime
Production
CO2 vol% 99.6 99.8 99.00 99.4 99.52
N2 vol% 0.29 0.0893
CO ppmv 1.2 1.2 1620 701 2000
Ar ppmv 11 11
H2O ppmv 640 640
NOX ppmv 2.5 (NO2) 0.86 (NO2) 3330 1690 1100
SOX ppmv 1.3 (SO2) < 0.1 (SO2) 4410 3030 1800
CO ppmv 1.2 1.2
O2 ppmv 35 35
CH4 ppmv 206
Cl ppmv 0.41 0.41 65.7 26.8
Ash ppmv 5.7
Hg ppmv 0.00073 0.1
As ppmv 0.29 0.0029
Se ppmv 1.2 0.0088
VOC ppmv 96.9
TOC ppmv 81
Last and Schmick,
Identification and
Selection of Major
Carbon Dioxide
Stream
Compositions.
US DOE

21. Summary of CO2 impurities
21CO2QUEST
Oxyfuel combustion
Pre-combustion Post-combustionRaw /
dehumidified
Double
flashing
Distillation
CO2 vol% 74.8-85.0 95.84-96.7 99.3-99.4 95-99 99.6 – 99.8
O2 vol% 3.21-6.0 1.05-1.2 0.01-0.4 0 0.015 – 0.0035
N2 vol% 5.80-16.6 1.6-2.03 0.01-0.2 0.0195 – 1 0.045 - 0.29
Ar vol% 2.3-4.47 0.4-0.61 0.01-0.1 0.0001-0.15 0.0011 – 0.021
NOX ppm 100-709 0-150 33-100 400 20 - 38.8
SO2 ppm 50-800 0-4500 37-50 25 0 - 67.1
SO3 ppm 20 - 20 - N.I.
H2O ppm 100-1000 0 0-100 0.1 -600 100 – 640
CO ppm 50 - 50 0 - 2000 1.2 - 10
H2S/COS ppm 0.2 - 34000
H2 ppm 20-30000
CH4 ppm 0-112

22. Concluding remarks
22CO2QUEST
 Few references on CO2 impurities and mainly based on theoretical
estimates
 CO2 impurity levels vary widely depending on fuel and technology type
 Actual purity levels of some hazardous species may be dictated by
transport and storage specifications:
• Corrosive species: SOX, NOX and water
• Fouling species
 Levels for benign species (e.g. N2, Ar) governed by full CCS chain
techno-economics
 Impurity levels can be reduced by adding additional or more intensive
process operations – implications for cost and capture rates

23. 23
Acknowledgements and Disclaimer
The research leading to the results described in this
presentation has received funding from the European
Union 7th Framework Programme FP7-ENERGY-2012-1-
2STAGE under grant agreement number 309102.
The presentation reflects only the authors’ views and the
European Union is not liable for any use that may be
made of the information contained therein.
CO2QUEST