SAFE Oxygen and Hydrogen Innovative Separation Techniques for Pre- and Oxy-combustion Capture

Transcription

1 SAFE 2009 Oxygen and Hydrogen Innovative Separation Techniques for Pre- and Oxy-combustion Capture

2 Contents Introduction (power cycles with CO 2 capture) H 2 separation membrane integration in power cycles synthesis processes and performances O 2 separation membranes integration in power cycles Conclusions 2

3 Power generation with CO 2 capture 3

4 Membrane integration in a power cycle H 2 separation membranes methane steam reforming (MSR) Water Gas Shift of syngas produced by MSR or coal gasification O 2 separation membranes oxyfuel combustion coal gasification for electricity and H 2 production 4

5 H 2 & electricity co-production / CO 2 capture where and why membranes? H 2 separation membranes can be integrated in the following processes: natural gas reforming : CH 4 +H 2 O CO + 3H 2 H = 206 kj mol-1 Water Gas Shift (WGS) from natural gas reforming or from coal gasification (IGCC): CO + H 2 O CO 2 + H 2 H = 41 kj mol-1 Membranes allow process intensification with capital and running cost reduction 5

6 Membrane reactor principle H 2 permeation through membrane shift the thermodynamic equilibrium: higher reaction conversions at the same temperature Same conversion at lower temperature 6

7 Membrane reactor (MR) in authotermal reforming (ATR) of natural gas Natural gas air Desulphurization steam CO 2 ASU N 2 O 2 steam Reformer Syngas H 2,CO,CO 2 WGS Reactor H 2 + CO 2 PSA H 2 MR combines reforming, WGS and separation in a single step (process intensification) 7

8 Membrane reformer for H 2 production installed at Tokio Gas Co. operating conditions : T = 550 C, P= 0. 9 MPa, H 2 O/C = 3-3.2; conversion:80% vs. 30% at TD equilibrium; H 2 purity >99.999%; 8

9 Membranes for H 2 separation in IGCC Air Membrane for O 2 N C, 18 bar separation O 2 steam Coal slurry Gassifier bar > 1050 C HT WGS Reactor H 2 + CO 2 WGS membrane reactor CO 2 + H 2 O Syngas (H 2,CO,CO 2) Heat exchanger Filtration and adsorbtion H 2 + N 2 9

10 CO 2 Capture in IGCC with membrane reactor (HSMR) Texaco technology with syngas cooler - Pd-Ag membrane P. Chiesa et al., proc. of GHGT 8, Trondheim (No) June 18-23,

11 Reducing membrane thickness is a key issue Middelton et al. Hydrogen production with CO 2 capture using membrane reactors GHGT 6 Kyoto, Japan October

12 Membranes for H 2 separation Classified on the basis of structure and separation mechanism porous dense H 2 trasport by molecular diffusion limited selectivity H 2 trasport by solubiliz.-diffusion or by protonic conductivity High selectivity 12

13 Dense membranes Membrane type Temperature ( C) Proton Conducting (ceramics, es. perovskites) Proton Conducting (composites) permeability Palladium & palladium salloys (on porous suppports) increase Composite metallic (sandwich structure FCC/BCC/FCC) 13

14 Dense metallic membranes for H 2 separation under development Mainly based on Pd and Pd alloys cold rolled to reduce thickness from 100 to 50 µm (infinite selectivity, e.g. high purity H 2 can be supplied to a fuel cell limited P, need of a support for most applications thin layer deposited by various methods on ceramic or metallic supports (thickness reduced to less than 5 µm) ceramic vs. metallic supports tradeoff: fragility, leak thigh seals, thermal expansion coefficient barrier layer to avoid poisoning of Pd by metal migration from support 14

15 Deposition processes for Pd-alloy membrane preparation on porous supports Electroless plating (WPI/Shell, Colorado School of Mines/Pall, ECN) Magneton sputtering (SRI, Sintef) CVD/PVD various laboratories 15

16 Pd Membranes preparation at ERSE Macroporous supports: austenitic stainless steels, Ni-Cr super-alloys with 0,1-0.2 µm nominal pore size Anti-diffusion barrier: grown-on oxide by oxidation in air at temperature D(m 2 /s) 1E-17 1E-19 1E-21 1E-23 Ceramic layer deposited by dipcoating 1E T( C) Pd, Pd alloys deposited by electroless plating 16

17 Pd membranes on oxidized PSS oxidized support Pd membrane 17

18 Multi-layer γ-alumina anti-diffusion barrier (a) as received AISI 316L support (b) after γ-alumina deposition 18

19 Pd membrane on oxidized PSS Permeation tests with pure gases 1.0E-06 permeance (mol/sec/m2/pa) 1.0E E E-09 T= 404 C He CO2 H2 1.0E E E E E E E E+05 P (Pa) 19

20 Pd membrane on oxidized PSS 600 selectivity H 2vs He (CO2) He358 CO2 358 He 402 CO E E E E E E E+05 p (Pa) Membranes tested up to 450 C and 8 bar for 2100 h with gas mixtures Limited selectivity due to defects in the Pd layer Good stability at temperature and thermal cycling 20

21 WGS tests with a palladium membrane reactor evaluate the performances of a palladium membrane reactor for WGS of a syngas produced in a IGCC at an intermediate temperature (400 C) N 2 Purified synthesis gas High T WGS -TR CO + H 2 O +H 2 + CO 2 Intermediate T WGS - MR H 2 +N 2 steam CO 2 syngas has already been treated in a conventional high temperature WGS reactor and CO concentration has been reduced below 8%. 21

22 WGS in a palladium membrane reactor pilot loop tests at ERSE WGS reaction: CO + H 2 O CO 2 + H 2 H 0 298= 41 kj mol -1 Feed composition feed 1 feed 2 %vol % vol CO H2O H CO H 2 O/CO commercial Fe/Cr catalyst V s =1580 h -1 P feed =1-6.5 bar Sweep gas = N 2 P sweep = atmospheric Counter-current mode 22

23 WGS with a traditional reactor (TR) TD equilibrium feed 1 TR feed 1 CO conversion (%) TD equilibrium feed 2 TR feed T ( C) 23

24 WGS in a palladium membrane reactor (MR) TD equilibrium feed 1 TR feed 1 TR feed 2 CO conversion (%) TD equilibrium feed 2 MR feed 1 MR feed T ( C) 24

25 WGS in a palladium membrane reactor CO conversion % MR feed 1 MR feed 2 Eq TD feed 1 Eq TD feed 2 TR feed 1 TR feed E E E E E E+05 P feed ( Pa) 25

26 WGS in a palladium membrane reactor HRF (%) H 2 purity (%) HRF H2 purity E E E E E+05 P feed (Pa) 26

27 WGS in a palladium membrane reactor CO conversion (%) MR feed 1 - cycle 7 MR feed 2 - ciclo 7 MR feed 1 - ciclo 6 MR feed 2 - ciclo 6 TR feed 1 TR feed HRF (%) 27

28 Where and why oxygen transport membranes (OTM) oxyfuel combustion coal gasification for electricity and H 2 production air separation unit (ASU) currently based on cryogenic technology: consumes about the 10% of the gross power output Systems studies indicates that replacement of cryogenic with OTM: Increase net MWe and IGCC plant efficiency Decrease cost of oxygen production and COE 28

29 Oxygen Transport Membranes (OTM) OTM are mixed conducting materials (dense ceramics) such as perovskites Crystal structure of perovskites (A 1-x A x B 1-y B y O 3-δ ) 29

30 Integration of a OTM in a Fluidized Bed Combustion P. Chiesa et. al Oxygen transport membranes and fluidized bed combustion for low CO 2 emission coal fired power plants CCT 2005, Cagliari (I), May

31 Integration of a OTM in a IGCC plant A. Pfeffer, European conference on CCS research, development and demonstration, Feb Oslo (No) 31

32 Integration of a OTM in a IGCC plant 32

33 Conclusions & developments Membranes for O 2 or H 2 separation can be a key component to develop power generation plants with CO 2 capture (precombustion and oxyfuel) membranes are now developed at laboratory stage developments Long-term stability and material optimization Module design (gas tight seals issue) scale-up of the production technology optimization of plant configuration start the demonstration phase 33