Research needs and opportunities for amine scrubbing for gas combustion

1. Research needs and opportunities for amine scrubbing for gas combustion Gary T. Rochelle Department of Chemical Engineering WORKSHOP ON TECHNOLOGY PATHWAYS FORWARD FOR CCS ON NATURAL GAS POWER SYSTEMS Washington, DC 20004 April 22, 2014

2. Messages • Bellingham demonstrated technical feasibility • Advanced processes improve economics, but need D & Demo • Better solvents • Better processes • Bigger & Better equipment • Environmental issues need preemptive resolution • Oxidation, Nitrosation, Amine reclaiming, Amine aerosols

3. Better Second Generation Solvents Propertiesat natural gas conditions,PCO2*= 0.1/1 kPa

4. DCC not needed for water Advanced Absorber for NGCC Less Packing, Richer Solvent No Prescubbing or DCC RECYCLE INTERCOOLING to Cool Gas RECYCLE INTERCOOLING TO Replace DCC Wet/Dry ??

5. Advanced flash stripper reduces Weq8 m PZ at 0.25 lean loading6 bar/150oC reduces compressor cost 20K LMTD CO2 Wpump= 4.4 kWh/tonne Wcomp= 67.6 Wreb= 155.3 WEQ= 227.3 6.2 bar Cold Rich BPS 9% Warm Rich BPS 30% 127 oC (BP) Qreb=2.3 GJ/tonne Rich Solvent 0.36 Ldg Flash Lean Solvent 0.25 Ldg 150 oC Avg DT=5 K

6. Gas takes 10% more energy than coal

7. Bigger and better Equipment needs D & D • Absorber- Single Vessel for 250 MW gas = 19 m • Square, concrete, low DP packing • Stripper - 7.5 m for 2 bar, 5 m for 8 bar • Reboiler/convective steam heater • Multiple, larger plate and frame exchangers • Materials Selection/Corrosion – CS, SS, Concrete, polymer? • Effective heat integration with NGCC • Optimum design/controls for peaking load operation

8. Oxidation • Amine Oxidation will be more significant with gas than with coal • O2/CO2 = 5 for gas vs 0.4 for coal • MEA makeup at Bellingham = 3 lbs/ton CO2 • Economically acceptable C= 2-3 $/ton CO2 • Environmentally questionable : NH3, aldehydes, et al. • Advances in Understanding, gained mostly with air/CO2: • catalysts/inhibitors; O2 mass transfer, thermal cycling • Identified mitigation options need to developed and demonstrated • N2 stripping, Inhibitors, Solvent Selection

9. Nitrosation • Secondary amines react quantitatively with NO2 to make carcinogenic nitrosamines, R2N-N=O • Nitrosation will be more significant with gas • NOx/CO2 = 10 ppm/3% > 10 ppm/12% • Because of degradation all solvents will nitrosate • Identified mitigation options need development & demonstration • Thermal decomposition at 150oC • Prescrubbing to remove NO2 • Reclaiming to concentrate and remove • Water Wash to avoid gas emissions

10. Solvent Reclaiming • Required fordegradation products, RNNO, sulfate, nitrate, metals • Effective reclaiming eliminates need for gas prescrubbing • Thermal reclaiming of nonvolatile impurities • Bellingham demonstrated1G thermal reclaiming w gas impurities • 2G thermal reclaiming will reduce amine losses • Less attractive alternatives – required for nonvolatile solvents • Ion exchange, Electrodialysis, Precipitation • Volatiles processing to remove NH3, aldehydes, et al. • All need development & demonstration with long term operation

11. Amine Aerosols / Water Wash • Amine aerosol growth degrades water wash performance • Amine aerosols will be less significant with gas • No SO3 or fly ash • However ambient particulate & SO2 may be problematic • Needs science and monitoring on variable gas sources

12. THE international meeting on CCSAustin Convention CenterHosted by UT with IEAGHGRochelle – co-chair of Steering1500+ participants Sponsorship opportunities: contribute $10k, 25k, or 50k Exhibitor: $5k www.GHGT.info October 5 - 9, 2014 | AUSTIN, TX - USA

13. NATURAL GAS TURBINE vs.COAL BOILER (8m PZ) PCO2, OUT ≈ 0.3 kPa PCO2, OUT ≈ 1.2 kPa P*CO2, LEAN ≈ 0.1 kPa P*CO2, LEAN ≈ 0.4 kPa P*CO2, RICH ≈ 1 kPa P*CO2, RICH ≈ 4 kPa PCO2, IN ≈ 3 kPa PCO2, IN ≈ 12 kPa

14. Opportunities: Natural Gas Turbine vs. Coal Boiler • Benefits of leaner loading range • Higher CO2 absorption rate constant • Increased free amine • ~2x coal reaction rate • Improved Operating Solvent Capacity • Flat VLE curve in NG loading range • ~20% increase in CO2 capacity per kg solvent circulated • Recycle intercooling to cool gas • Cool gas in absorber to reduce overall column temperatures

15. Challenges: Natural Gas Turbine vs. Coal Boiler • Lower flue gas CO2 concentration => Smaller driving force • Coal: ~3.2 kPa LMPD; NG: ~0.8 kPa LMPD • Lower CO2 pressure in stripper (leaner loading range => reduced PCO2) • More mechanical compression • More H2O vapor per mole of CO2 (irreversible losses in condensation) • Larger gas volume • Column diameter increases • Blower size increases

16. Reddy et al., 2003 Chapel et al., 1999 Sander & Mariz, 1992 Bellingham, NGCC, 1991-200598.5% on stream in 2004 14 tonne/hr AirCooled 1.5-2 bar 40 MW Slipstrm 13 % O2 3 % CO2 7? % H2O 150? oC 4.2 GJ/t (?) 30-50 psig Kettle 110-1200C 3 lbs MEA/t CO2makeup (?)

17. Bellingham, NGCC, Fluor Sander and Mariz, 1992 Absorber 7.5x55 m Stripper 3x40 m DCC 8.4x21m

18. Case Studies • Combined cycle gas turbine • 3 – 4.5% CO2; 6 – 8% H2O • 8m PZ solvent • LLDG = 0.25 mols CO2/mols alkalinity • NEW ABSORBER CONCEPTS • Recycle Intercooling • Removing Direct Contact Cooler

19. No Intercooling

21. Simple Intercooling

22. Recycle Intercooling

24. Removing the Direct Contact Cooler

25. BASE CASE WITH DCC RECYCLE INTERCOOLING

27. NEW DESIGN NO DCC RECYCLE INTERCOOLING RECYCLE TO REPLACE DCC

29. No DCC vs. DCC • Nearly identical absorber packing requirement & rich loading • Performance &profiles without DCC replicate DCC case • Trade-off: Additional intercooling loop vs. cost of DCC • Operational risk: reliability of wet-dry interface

30. Simple Stripper using 8 m PZ6 bar/150oC reduces compressor cost Condenser CO2 150 bar 6~12 bar ~140 oC Cross exchanger CO2 Rich Solvent Stripper 1 bar 150 oC Compressor Pump Reboiler CO2 Lean Solvent Trim cooler 30

31. Reboiler duty (GJ/tonneCO2)

32. Energy Analysis Estimated Total Equivalent Work 12% CO2, 90% Removal, 150 bar, 40 °C Minimum Work = 109 kWh/tonne = 0.39 GJ/t CO2 Separation = 46 kWh/tonne = 0.17 GJ/t Compression = 63 kWh/tonne = 0.23 GJ/t