2nd Workshop International Oxy-Combustion Research Network Hilton Garden Inn Windsor, CT, USA 25th and 26th January 2007 Hosted by: Alstom Power Inc. PRESENTATION - 10 Purification of Oxyfuel Derived for Sequestration or EOR by: Vince White Air Products PLC, UK
Purification of Oxyfuel-Derived for Sequestration or EOR Vince White Air Products PLC, UK 25 th January 2007 Purification of Oxyfuel-Derived for Sequestration or EOR produced from oxyfuel requires purification Cooling to remove water Inerts removal Compression Current design has limitations SOx/NOx removal Oxygen removal Recovery limited by phase separation New concepts for purification have been developed (since the IEA GHG Oxyfuel report) 2 2nd Int'l Oxy-Combustion Workshop Page 1
Flue Gas Vent 1.1 bar 20 C 25% 75% inerts Compression and Purification System Inerts removal and compression to 110 bar Flue Gas Expander Flue Gas Heater Aluminium plate/fin exchanger -55 C Driers 3 30 bar Raw 76% 24% Inerts product 110 bar 96% 4% Inerts -60 C dp Purity Depends On Feed Pressure 1 0.98 Composition 0.96 0.94 0.92 0.9 10 20 30 40 50 60 Feed Pressure, bar At -55 C 4 2nd Int'l Oxy-Combustion Workshop Page 2
Recovery Depends On Feed Composition 1 0.8 Recovery 0.6 0.4 0.2 0 0 0.2 0.4 0.6 0.8 Feed Composition At -55 C, 30 bar 5 Recovery Depends On Feed Composition 0.30 0.25 Vent Composition 0.20 0.15 0.10 0.05 0.00 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Feed Composition At -55 C, 30 bar 6 2nd Int'l Oxy-Combustion Workshop Page 3
Purity and Recovery -55 C is as cold as we can make the phase separation purity depends on pressure At 30 bar and -55 C, purity is 95% Higher pressure gives lower purity recovery depends on pressure Lower pressure gives lower recovery At 15 bar and -55 C, recovery is 75% At 30 bar and -55 C, recovery is 90% recovery depends on feed composition Increases from zero at 25mol% to 90% at 75mol% Reducing air ingress increases capture rate 7 Raw and Product Compositions Raw Flue Gas Product Vent @ 35 C, 1.02 bara @ 35 C, 110 bar @ 11 C, 1.1 bar mol% mol% mol% Prior Art Prior Art N 2 O 2 71.5 95.8 24.6 14.3 2.0 48.7 5.9 1.1 19.4 Ar 2.3 0.6 7.1 SO 2 0.4 0.5 0 NO 400 ppm 13 ppm 1180 ppm NO 2 10 ppm 0 0 H 2 O 5.6 0 0 8 2nd Int'l Oxy-Combustion Workshop Page 4
Purity Issues H 2 O SO 2 NO O 2 Ar + N 2 + O 2 Basic Design Case < 500 ppm > 90% mol From H&MB From H&MB < 4% mol < 4% mol EOR Case < 50 ppm > 90% mol < 50 ppm From H&MB 100 ppm < 4% mol Regulations regarding onshore and off-shore disposal are being drafted world-wide Co-disposal of other wastes (NOx, SOx, Hg) is a sensitive issue Important that the can be purified for disposal or EOR 9 NOx SO 2 Reactions in the Compression System We realised that SO 2, NOx and Hg can be removed in the compression process, in the presence of water and oxygen. SO 2 is converted to Sulphuric Acid, NO 2 converted to Nitric Acid: NO + ½ O 2 = NO 2 (1) Slow 2 NO 2 = N 2 O 4 (2) Fast 2 NO 2 + H 2 O = HNO 2 + HNO 3 (3) Slow 3 HNO 2 = HNO 3 + 2 NO + H 2 O (4) Fast NO 2 + SO 2 = NO + SO 3 (5) Fast SO 3 + H 2 O = H 2 SO 4 (6) Fast Rate increases with Pressure to the 3 rd power only feasible at elevated pressure No Nitric Acid is formed until all the SO 2 is converted Pressure, reactor design and residence times, are important. 10 2nd Int'l Oxy-Combustion Workshop Page 5
Compression and Purification System Removal of SO 2, NOx and Hg 1.02 bar 30 C 67% 8% H 2 O 25% Inerts SOx NOx SO 2 removal: 100% NOx removal: 90-99% BFW Condensate 15 bar 30 bar cw Water 30 bar to Driers 76% 24% Inerts cw cw Dilute HNO 3 11 Dilute H 2 SO 4 HNO 3 Hg SOx/NOx Removal Key Features Adiabatic compression to 15 bar: No interstage water removal All Water and SOx removed at one place NO acts as a catalyst NO is oxidised to NO 2 and then NO 2 oxidises SO 2 to SO 3 : The Lead Chamber Process Hg will also be removed, reacting with the nitric acid that is formed 12 2nd Int'l Oxy-Combustion Workshop Page 6
Corrected Purity Raw Flue Gas Product Vent Product Vent @ 35 C, 1.02 bara @ 35 C, 110 bar @ 11 C, 1.1 bar @ 35 C, 110 bar @ 11 C, 1.1 bar mol% mol% mol% mol% mol% Prior Art Prior Art Corrected Corrected N 2 O 2 71.5 95.8 24.6 96.3 24.6 14.3 2.0 48.7 2.0 48.7 5.9 1.1 19.4 1.1 19.4 Ar 2.3 0.6 7.1 0.6 7.1 SO 2 0.4 0.5 0 0 0 NO 400 ppm 13 ppm 1180 ppm < 10 ppm < 100 ppm NO 2 10 ppm 0 0 < 10 ppm 0 H 2 O 5.6 0 0 0 0 13 And Oxygen removal from the? Where does the distillation column go? Driers 14 30 bar Raw 76% 24% Inerts 2nd Int'l Oxy-Combustion Workshop Page 7
Oxygen removal Option 1 Driers Remove this Feed to distillation column 15 30 bar Raw 76% 24% Inerts Oxygen removal Option 1 Recycle to Feed Impure 17 bar column Pure To exchanger for refrigeration duty Reboiler heated with feed stream 16 2nd Int'l Oxy-Combustion Workshop Page 8
Oxygen removal Option 2 Driers Feed to distillation column 17 30 bar Raw 76% 24% Inerts Oxygen removal Option 2 Recycle to Feed Impure 30 bar column Pure Pump to pipeline pressure or flash to tanker pressure Reboiler heated with feed stream 18 2nd Int'l Oxy-Combustion Workshop Page 9
Can we improve on 89% Capture? Vent stream is at pressure and is (and O 2 ) rich Driers 19 30 bar Raw 76% 24% Inerts Put membrane in vent stream Recycle and O 2 rich stream to boiler To Boiler Membrane Driers 20 30 bar Raw 76% 24% Inerts 2nd Int'l Oxy-Combustion Workshop Page 10
Purity, Recovery and Power Power includes ASU and system power Description Purity Oxygen Content Pressure Recovery Relative Specific Power Standard Cycle 95.90 mol% 0.91 mol% 110 bar 89.0% 1.00 High Purity Option 1 99.89 mol% 100.00 ppm 110 bar 87.4% 1.03 High Purity Option 2 99.98 mol% 100.00 ppm 110 bar 87.7% 0.99 30 bar liquid 99.98 mol% 100.00 ppm 30 bar 87.7% 0.98 7 bar liquid 100.00 mol% 5.01 ppm 7 bar 87.7% 1.02 Standard with membrane High purity Option 1 with membrane 96.30 mol% 0.73 mol% 110 bar 97.7% 0.91 99.86 mol% 100.00 ppm 110 bar 97.9% 0.97 21 Conclusions FGD and DeNOx systems are not required to meet tight purity specifications Co-disposal of SO 2 with is not possible Compressing with NO + SO 2 + O 2 + Water will result in H 2 SO 4 production Low NOx burners are not required for oxyfuel combustion Oxygen can be removed for EOR-grade No penalty if liquid is required Capture of increased to 98% with membrane Also reduces ASU size (~5% reduction) 22 2nd Int'l Oxy-Combustion Workshop Page 11
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