Overview on 1 st and 2 nd generation coal-fired membrane power plants (with and without turbo machinery in the membrane environment)

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1 Mitglied der Helmholtz-Gemeinschaft Fourth International Conference on Clean Coal Technologies CCT Dresden, Germany May Overview on 1 st and 2 nd generation coal-fired membrane power plants (with and without turbo machinery in the membrane environment) L. Blum, E. Riensche, J. Nazarko, R. Menzer, D. Stolten Jülich Forschungszentrum, D Jülich Institute for Energy Research Fuel Cells (IEF-3) 2. Juni 2009

2 Contents A membrane application of today: separation from natural gas Coal-fired membrane power plants (MPPs) Classification Several concepts in development - 1 st generation MPPs: Compressors required for membrane operation IG-SWEEP-JÜL - Opening the road to 2 nd generation MPPs w/o additional turbo machinery in the membrane environment Driving force by dilution of H 2 into a sweep gas (in modified IGCC) Bild 2

3 Removal from Natural Gas by Polymer Membranes Natural gas pressure ~ 100 bar!!! Arian Nijmeijer / SHELL One of the industrial partners of FZJ in the HGF Alliance MEM-BRAIN Bild 3

4 Removal from Natural Gas (CH 4 ) Example: NG 100 bar 10 mol% Membrane environment no compressor p CO2 = 10 bar Retentate no vacuum pump Permeate 1 bar Pure p ~ p CO2 = 1 bar Natural driving force for permeation No el. energy is needed Bild 4

5 Natural Driving Force in Membrane Power Plants? Bild 5

6 Post-combustion: Membrane + Vacuum Pump Air λ~1 Basic steam power plant Flue gas 70 C 1 bar Membrane environment 140 mbar Retentate Coal 14 mol% N 2 N 2 Vacuum pump Permeate 1 bar Pure 30 mbar Transport law for polymer and porous ceramic membranes: Local permeation flux density = permeability * Δp CO2 (Feed side - Permeate side) Driving force for permeation El. Power: 106 kwh/t separated for purity: 80 mol% Vacuum: 30 mbar (PRO/II simulation) liquefaction: ~ kwh/t Bild 6

7 The Idea of a Sweep Gas: Driving Force by Dilution!? no compressor Membrane environment Flue gas p CO2 = 140 mbar Retentate no vacuum pump Sweep gas + Sweep gas p CO2 ~ 50 mbar 0 mbar but dilution into a sweep gas produces impure again!!! Bild 7

8 besides post-combustion: Driving Force by Dilution into a Sweep Gas in Membrane Power Plants? Bild 8

9 Coal-Fired Membrane Power Plants Classification Bild 9

10 3 Capture Principles 4 Membrane Gas Separation Classes Post-combustion Combustion with air capture from FG Flue gas N 2 + Impurities N 2 (O 2 ) from membrane Air N 2 O 2 Coal + O 2 Oxyfuel O 2 separation from air Combustion with O 2 Cooling by recycling H 2 O + + Impurities Condensation + O 2 (N 2 ) from plant Shifted coal gas (pressurized) Special polymer membranes: The larger molecule permeates! H 2 H 2 Pre-combustion/H 2 or / Partial oxidation (gasific.) CO shift to H 2 or separation H 2 combustion Bild 10

11 Separated Gas Components: Pure or Diluted Post-combustion Flue gas Dilution of O 2 or H 2 pure diluted N 2 2 Chances for successful sweep!!! Air N 2 O 2 O 2 pure Oxyfuel O 2 diluted Pre-combustion / H 2 -sep H 2 H 2 pure H 2 diluted Dilution of impure again Shifted coal gas Pre-combustion / -sep no chance for successful sweep!!! H 2 pure diluted Bild 11

12 3 Capture Principles 3 Technology Platforms 6 Capture classes are of interest for MPPs Pre-comb/H 2 or / Oxyfuel Post-combustion Coal Air or O 2 combustion (atm. ) SPP (Steam Power Plant) not possible 2 SPP / Oxyfuel 1 SPP / Post-comb. Coal O 2 Steam gasification Air or O CO, H 2 2 combustion IGCC Coal O 2 Steam gasification not possible Excess steam, H 2 CO shift 4 IGCC/ Total-oxyfuel Air combustion 3 IGCC / Post-comb. IGCC+Shift/H2GT 5 and 6 IGCC+ / Pre-c. not the best solution not the best solution IGCC: Integrated Gasification Combined Cycle Bild 12

13 Class 2 SPP / Oxyfuel Bild 13

14 3 Measures for Driving Force in the Membrane Feed side (air): Compressor / Expander 1 Pure O 2 OTM-Clean /Pressurized Permeate side (O 2 ): Vacuum pump 2 Permeate side: Sweep gas = Hot recycled flue gas Pure O Diluted O 2 OXYVAC-JÜL OXYCOAL-AC Bild 14

15 NG OXYVAC-JÜL : Permeate Compression (Vacuum Pump) Basic variant: Some NG is burned for final air preheating MIEC Unit Air Recuperative heat ~750 C ~800 C 1 bar O 2 50 mbar po2 Feed /po2 Perm =4:1 2:1 po2 200 Feed 100 mbar po2 50 Perm 50 mbar Depleted air O 2 Vacuum pump PRO/II simulation: Oxyfuel unit as in conventional separation plant 50 mbar 1 bar 1 bar ~200 C Recycling Source: Meulenberg, Baumann, Blum, Riensche: Deutsche Patentanmeldung (PT ) Bild 15 O 2 Low pressure differences in HT air preheater & HT membrane MIEC (Mixed Ionic Electronic Conductor) Oxyfuel Unit Coal Δη = about -10 %p incl. liquefaction Steam generator H 2 O Compress.

16 OXYCOAL-AC : Sweep Gas & Compression Air 20 bar 750 C MIEC 20 bar 800 C 1 bar High temperature recuperator O C 500 C Coal Steam generator Flue gas (, H 2 O, O 2, N 2 ) Δη = about 9 %p incl. liquefaction [Beggel (RWTH) 2008] Cleaning 850 C 1 bar Advantage: High driving forces Feed p /p Perm Theoretical case: Sweep w/o compression O2 O2 20:1 70:1 O 2 : ~200 mbar in air Feed p O mbar ~200 mbar in sweep gas Driving force missing Perm p O2 ~200 ~30 mbar Reason: Air ratio low (λ~1) in SPPs small flow rates of cooling media small flow rates for sweep gases H 2 O Bild 16

17 Class 4 IGCC / Total-oxyfuel For O 2 membranes IGCCs have a potential for large sweep gas streams. Concepts may be developed in future. Bild 17

18 Class 5 IGCC+Shift/H2GT / Pre-comb./H2-sep Bild 18

19 Pre-combustion: Pure H 2 is Separated - Combined with Recompression Standard membrane concept Coal Steam ASU Gasif. Clean. C O 2 25 bar Compressed air incl. CO Shift CO+H2O =CO2+H2 press. N 2 Steam line Membrane environment, H 2, Press. (H 2 ), Impur. Impurities 0.5 bar H 2 H 2 H 2 Recompression 25 bar Pressure level of all process gases: 25 bar except H 2 permeate for sweep too much O2 λ~2.5!!! ~1200 C Energetic losses Excess steam for shift H 2 recompression!!! C GT G Δη -10 %-points [Göttlicher, VDI-Ber. 421, 1999] Excess air O 2, N 2 Flue gas H 2 O, N 2, O 2 HRSG ST G Bild 19

20 2 nd GENERATION MEMBRANE PP CONCEPT: WITHOUT ADDITIONAL TURBO MACHINERY IN THE MEMBRANE ENVIRONMENT Bild 20

21 Membrane Operation w/o Energy Supply H 2 dilution by sweep gas w/o O 2 Membrane environment no compressor Shifted coal gas + H 2 Sweep gas + permeate to GT burner N 2 + H 2 H 2 N 2 no vacuum pump Sweep gas = Recycled flue gas IG-SWEEP-JÜL Sources: Menzer, Riensche, Peters, Blum, Scherer: Deutsche Patentanmeldung DE , Riensche, Menzer, Blum: Deutsche Patentanmeldung DE , Bild 21

22 IGCC Modified to IG-SWEEP-JÜL Stoichiometric combustion & Recycling of the flue gas: N 2 (O 2 -free) Steam Membrane environment Steam line Coal, H 2 Press. Gasif. Clean. C ASU O 2 25 bar Compressed air incl. CO shift Press. N 2 PRO/II simulation Pressure level of all process gases: 25 bar H 2 ~400 C Porous ceramic membrane N 2 /H 2 ~4 mol/mol N 2, H 2 Press. N 2 Sweep gas 2: N 2 N 2 /H 2 ~6 mol/mol λ=1 no O 2 ~1200 C C C GT G Flue gas recycling: N 2 Sweep gas 1: N 2 Stoich. Air: O 2, N 2 Flue gas: HRSG ST N 2 G H 2 O Bild 22

23 Membrane in IGSWEEP-JÜL - H 2 Partial Pressure Profiles 25 bar High ratio: Sweep gas / permeated H 2 ~ 4:1 mol/mol!!! 15 bar H 2, Highest H 2 separation degrees possible!!! H 2 Partial pressure 5 bar 4N 2 +H 2 High driving forces Sweep gas 0 0 H 2 Separation degree 50% Feed side Permeate side Sweep gas = 4N 2 (no H 2!!!) 98% Bild 23

24 Conclusions Natural driving forces for permeation do not exist in MPPs, if pure gas components are separated (, O 2, H 2 ): Compressors consume much energy (comparable to liquefaction). IG-SWEEP-JÜL opens a new PP route of 2 nd generation MPPs with energy-free dilution of permeating H 2 (or O 2 ) into a sweep gas. Large sweep gas streams are required and could be found in IGCC modifications w/o significant additional energy demand. The total efficiency penalty may approach 5 %-points (after optimization): capture ~1 %p (parasitic losses) liquefaction 4 %p Bild 24

25 Coal power plants: ~40% of anthropogenic emissions!!! We need: worldwide acceptable CCS energy-free capture optimal membrane integration THANK YOU FOR YOUR ATTENTION Bild 25

26 Appendix Bild 26

27 What is an Acceptable Capture Technology? 1 High purity! In discussion: >80 mol%??? >90 mol% (work hypothesis here) >95 mol% (MEA as benchmark) 2 Low efficiency losses! Hypothesis for successful CCS: All nations of the world may accept year by year 10% more coal input or 10% loss in power production, but not more. η ~ 50% for modern PPs Acceptable Δη: -5 %-points (CCS) Compression: Δη = -3 to -4 %-points [literature] For capture: Acceptable Δη: -1 to -2 %-points Bild 27

28 Fossil-Fired Power Plants w/o Capture NG Boiler only a few exist NGCC NG Combined Cycle Natural gas Natural gas atmospheric combustion pressurized combustion ST GT ST η high ~58% Oil Fired PPs only a few exist SPP Steam Power Plant SPP pressurized not realized Coal Coal atmospheric combustion ST η ~45% mean η world ~30% pressurized combustion GT ST not realized in large scale IGCC Integrated Gasif. CC only a few exist Coal CO, H 2 gasification O 2 Steam Air pressurized combustion GT ST η high ~50% GT: Gas Turbine ST: Steam Turbine Bild 28

29 The Idea of a Sweep Gas for Dilution Flue gas no compressor Membrane environment p = 1 bar p CO2 = 140 mbar ~50 mbar Retentate no vacuum pump Sweep gas + Sweep gas w/o p CO2 ~ 50 mbar 0 mbar A tricky solution, if sweep gas available (p=1 bar or <1 bar) flowrate sufficient large sweep gas suitable for the membrane and [sweep gas + permeate] are welcome downstream but for Post combustion no sweep gas is found up to now Bild 29

30 But How to Remove from Atmospheric Flue Gas??? Air λ~1 Basic steam power plant Flue gas Membrane environment p = 1 bar p CO2 = 140 mbar no compressor Retentate no vacuum pump Coal Air p CO2 =0.3 mbar Air (O 2, N 2 ) dilution in air??? General question in membrane plant development: Are there other ways besides energy consuming compression to realize a positive driving force??? Bild 30

31 Low Driving Force for Permeation even at Membrane Inlet 1 bar Feed pressure 1 bar Permeate pressure 30 mbar Driving force for decreases, but not for N 2 partial pressure 140 mbar Driving force membrane inlet 110 mbar Feed (Flue gas) Driving force membrane outlet 40 mbar 30 mbar Permeate 0 0 separation degree 50% 100% Bild 31

32 Impurities Strongly Important in a Large Oxyfuel Plant Steam generator N 2 Air ASU O 2 (N 2 ) Coal Cleaning to compr. N 2 +Ar: 5 mol% O 2 : 95 mol% Flue gas, H 2 O, O 2, N 2 1 bar cold cold H 2 O Remark N 2 < 1 mol% is target for an excellent O 2 membrane [MEMBRAIN proposal 2007] O 2 content: 4-8 mol% Air leackage Expected purity: about mol% Compression Pipeline Source: Oxyfuel Conference, Cottbus, April 2007 Bild 32

33 OTM-clean/Pressurized with Cold Flue Gas Recycling Air Preheating in Steam Generator Air 20 bar Steam generator 800 C O 2 O 2 1 bar OTM-clean Coal Flue gas, H 2 O, O 2, N 2 1 bar Cleaning cold H 2 O Disadvantage: Low driving forces Feed p /p Perm O2 O2 4:1 2:1 Feed p O2 4 2 bar Perm p O2 1 1 bar Bild 33

34 IGCC/Total-Oxyfuel: O 2 Gasification & O 2 Combustion Advantage: 1-stage capture w/o CO shift Steam line Coal Air Air Steam O 2 Small ASU Gasification Large ASU O 2 Coal gas CO, H 2 Vision for Membrane PPs For O 2 membranes large sweep gas streams would be available (pressurized): p O2 (Feed) / p O2 (Permeate) = 21/12 ~ 2:1!!! [Göttlicher, VDI-Ber. 421, 1999] Combined Cycle with large (!!!) FG recycle stream Flue gas, H 2 O Pressure level of all process gases: 25 bar Source: after SIEMENS, Pictures of the Future, Spring 2008 Bild 34

35 Transport Mechanisms of Inorganic Membranes Dense membranes can perfectly select O 2 and H 2 electrochemically C MIEC: Mixed Ionic Electronic Conductor, O 2 /N 2 selectivity ~100,000:1!!! (theoretically) After: Caro (Univ. Hannover) 2007 O 2-2 e C H Multi-layer and/or specific adsorption: carbons, zeolites, amorphous SiO 2 Molecular Sieves: zeolite, carbons, amorphous SiO 2 Ionic transport (solid electrolytes): O 2-, H + in perovskites C Atomic transport of H: metals, e.g. Ag/Pd, Nb, V, Ta MPEC: Mixed Protonic Electronic Conductor MPEC Bild 35