Investigations about cofiring of herbaceous biomass in an Integrated Gasification Combined Cycle

Transcription

1 Investigations about cofiring of herbaceous biomass in an Integrated Gasification Combined Cycle J. Judex, S. Daniele, J.-L. Hersener, S. Biollaz, P. Jansohn presented by Tilman Schildhauer 3rd Freiberg Conference on IGCC and XtL Technologies, May 2009, Dresden

2 Motivation Background: increasing electricity demand, but shutdown of old nuclear power plants in Switzerland Using biomass for CO 2 reduction and improved sustainability Limited biomass resources Testing grass/hay as additional bio fuel for power production via B-IGCC 2

3 Structure of the presentation GIS analysis (availability) Gasification experiments with grass as fuel (gas quality) Combustion experiments with product gas-natural gas mixtures (combustion characteristics) availability 3

4 Structure of the presentation GIS analysis (availability) Gasification experiments with grass as fuel (gas quality) Combustion experiments with product gas-natural gas mixtures (combustion characteristics) gas quality availability 4

5 Structure of the presentation GIS analysis (availability) Gasification experiments with grass as fuel (gas quality) Combustion experiments with product gas-natural gas mixtures (combustion characteristics) combustion characteristics gas quality availability 5

6 GIS analysis Base material (Swiss Areal Statistik ): grassy grounds Filters: tilt, orientation, elevation, precipitation, exposition Restrictions: only minor soil quality (no competition energy vs. food!) each circle contains 32 kt dry substance per year of herbaceous material 6

7 10 : 90 % LHV biomass to natural gas IGCC: size, efficiency 6000 operating hours NG : Biosyngas 10% : 90% by LHV 45% : 55% by gas volume LHV mixed gas 21 MJ/m 3 37 MW el total 7

8 Gasifcation of grass: trace species in the fuel [g/kg] hay wood 5 0 Ca K Mg Na Ba S Si 8

9 Fuel quality requirements by GT Element Limit average lit. Current mixture K, Na < mg/m V,< mg/m Ca, < mg/m Ba, < mg/m 3 NA P, < mg/m 3 NA Cd, < mg/m 3 NA Cofiring fraction ~ 45% dilution factor 0.65 Volume increase during combustion (λ = 4 incl. secondary air) 5.7 9

10 Gasification experiments in bubbling fluidised bed flare filter grass pellet container bubbling fluidised bed 10 air Continuous operation for grass and air Accumulation of ash in the bed Variation of bed materials, λ, T,.. Conversion, trace elements and slagging

11 Sampling and measurements solvent filter raw gas continuous wet sampling permanent gases Micro-GC solvent, tars, particles (99%) ICP-OES Continuous operation for grass and air Accumulation of ash in the bed Variation of bed materials, λ, T,.. Conversion, trace elements and slagging 11

12 Gas species (micro-gc) and metal traces (ICP-OES) Concentration, μg/l gas Concentration, %vol :00:00 15:00:00 C 2 H 6 18:00:00 clock time N 2 CO 2 H 2 CO CH 4 K Na Ba P Ca Cd V LHV 4.7 MJ/m 3 Fuel dried hay Bedmat. SiO 2 Temp. 700 C Press. ambient :00 15:00 18:00 clock time 12

13 Optically accessible combustion test rig (LIF, chemoluminiscence) Syngas / Air To ICCD Camera To PMs Array Air flow rate: Air preheating temperature: Pressure: Thermal power: max. 270 g/s max. 823 K max. 30 bar max. 400 kw 13

14 Combustion chraracteristics: turbulent flame speed Turbulent Flame Speed turbulent flame speed [m/s] CH4 H2-CO-CH H2-CO H2-CO Increasing syngas fraction Increasing syngas fraction adiabatic flame temperature [K] Co-firing looks achievable for a GT requiring only minor modifications A fully fuel flexible engine represents still a major challenge 14

15 NO x emissions depend on gas mixture and temperature pure syngas CH 4 co-firing syngas Lower NOx for co-firing mixture: Different pathway for H x C y oxidation 15

16 Conclusions Grass is an available fuel for gasification Grounds are possessed by mostly private persons Amount in CH is significant but the security of supply is critical Gasification experiments proved stable operation at certain conditions Contaminants in the gas phase are below the limits Ammonia content in syngas < ca. 450 ppmv to limit NO x Combustion with proposed mixtures (co-firing 10% of LHV) is possible with only minor adaption of burner and chamber 16

17 Thank you for your attention 17

18 Gas mixture composition 18

19 BFB in detail (1) Fuel storage (2) rotary feeder (3) feeder (4) auger (water cooled) (5) inlet gasification agent 7 (6) reactor (7) freeboard (8) sampling ports (9) cyclone (10) flare (11) warm gas particle filter

20 Flame Speed Laminar Flame Speed Normalized Turbulent Flame Speed adiabatic flame temperature 1650 [K] 1850 CH4 H2-CO-CH H2-CO H2-CO-N H2-CO adiabatic flame temperature 1650 [K] 1850 CH4 H2-CO-CH H2-CO H2-CO-N H2-CO laminar fame speed [m/s] turbulent flame speed factor wrt CH4 Depending on their hydrogen-content the fuel mixtures have the ability to propagate faster, independently on the temperature The ability to propagate faster, depends on the temperature; the effect is due to the different physical properties of H 2 co-firing looks achievable for a GT requiring only minor modifications a fully flexible engine represents still a major challenge 20

21 Experimental matrix Olivine Al2O3 green: stable process yelllow: unstable process red: not conducted because of risk of gray: not yet conducted slagging dolomite 700 C SiO2 dolimite: tensile strength is too weak for fluidized bed gasification (Mohs hardness 4) SiO2: shows melting behaviour at 750 C because of alkali influence 750 C Al2O3: unfavorable carbon conversion Olivin: NaN 800 C 0.17 ER