Emissions Characterization of Three High Efficiency Wood Boilers

Transcription

1 Emissions Characterization of Three High Efficiency Wood Boilers James Laing, Sriraam Ramanathan Chandrasekaran, Suresh Raja, Thomas Holsen, Philip K. Hopke Center for Air Resources Engineering and Science, Clarkson University, Potsdam, NY Woody Biomass Energy Research Symposium University of Vermont, Burlington, VT, April 2830, 2011

2 Outline Study Objectives Boiler Description Sampling system Demonstrate near complete combustion Effect of Fuel Quality on Emissions PM chemical characterization Conclusions

3 Objectives of this study Demonstrate high efficiency, low emission European biomass combustion technology in the US Determine emissions dependence on fuel quality and fuel load Chemically characterize fine particulate matter (PM2.5)

4 Boilers Studied Advanced Climate Technologies, LLC, Schenectady, NY Two 150kW (514,000 Btu/hr) Output Boilers (Clarkson University, ACT facilities) 500kw (1.7 MM Btu/hr) Output (Wild Center, Tupper Lake)

5 Boiler Technology Air staging technology for near-complete combustion tertiary zone λ > 1 secondary zone λ > 1 primary zone λ < 1 fuel augur ash removal augurs

6 Sampling System Dilution Chamber Hot Box Sampling Ports Lipsky & Robinson (2006) HEPA filtered dilution air Heated Probe

7 Complete Combustion? Complete Combustion of Hydrocarbons CH 4 + 2O 2 CO 2 + 2H 2 O CO concentrations variable for Wild Center boiler because it was not running at steady state Concnetration [mg/mj] Wood Pellets Wood Chips Wild Center

8 Complete Combustion? Low CO concentrations when running at steady-state Low OC fraction of PM 2.5 Most of the carbon in the fuel fully oxidized to CO 2 OC EC Na + K + Ca + Mg + SO 4 2- Cl - NO 3- Zn Unresolved

9 Fuel composition Fuel composition can lead to higher emissions of criteria pollutants NO x, SO 2, PM 2.5 Fuel Property Wood Pellets (Walker) 150 kw Wood Chips (ACT Bioenergy) Curran Pellets (Wild Center) 500 kw 150 kw Heat Content (MJ/lbs) Moisture (%) Ash (d.w. %) Carbon (d.w. %) Nitrogen (d.w. %) Sulfur (d.w. ppm)

10 Wild Center Wood Chips Wood Pellets NO x Concnetration [mg/mj]

11 Wild Center Wood Chips Wood Pellets SO 2 Concnetration [mg/mj]

12 Wild Center Wood Chips Wood Pellets PM 2.5 Concnetration [mg/mj]

13 Fine Particle Formation Organic Particles Condensation and/or nucleation of organic vapors Dependent on fuel quality Inorganic Particles Condensation of alkali chlorides Fine Particles (soot, alkali salts, organic matter) Dependent on Combustion Soot Oxidation and burn out Agglomeration Coagulation and condensation Surface growth and coagulation Formation of core particles Formation of primary soot particles Nucleation and condensation of alkali sulfates and Zinc Formation of Soot nuclei Oxidation and sulfation Vaporization (K, Na, S, Cl, Zn) PAH formation and polymerization Lightly et al. 2000, Tissari et al. 2008

14 Complete/Incomplete combustion Incomplete mostly Organic Carbon Complete mostly inorganic salts Toxicity depends on combustion conditions* Certain organic compounds (such as PAHs) are carcinogens or mutagens *Bölling 2009; Klippel & Nussbaumer 2007

15 Fine PM Chemical Composition from Wood Pellets Unresolved Cl - (0.44%) w t.% of PM SO 4 - NO 3 - (0.49%) 20 0 K + OC Na + (0.18%) Zn (0.15%)

16 Ultrafine Particle Number Size Distribution 2e+81.4e+8 3e+9 Start-up & Steady-state dn/dlogdp [#/cm 3 ] dn/dlogdp [#/cm 3 ] 1.2e+8 2e+8 1.0e+8 1e+8 8.0e+7 6.0e+7 4.0e+7 5e+7 2.0e+7 Start-up Steady State Shutdown Wood Chips Wood Pellets A Wild Center 3e+9 2e+9 2e+9 1e+9 5e+8 Shut-down dn/dlogdp [#/cm 3 ] Electrical Electrical Mobility Mobility Diameter Diameter [nm] [nm]

17 Trace Metals Trace metals wt.% PM 2.5 Particle surface enriched with trace elements* Health implications due to higher bioavailability Cd, Pb, Tl, and Zn were enriched in fine PM (recoveries >30%) Element Al Ba Cd Co Cr Cu Li Mg Recovery in PM 2.5 (wt. %) < < Element Mn Ni Pb Rb Tl V Zn Recovery in PM 2.5 (wt. %) 0.46 < *Lightly 2000

18 Conclusions Advanced Climate Technologies Boilers demonstrated emission factors equivalent to the leading biomass combustion technology in Europe Emissions dependent on fuel High N in fuel higher NO x emissions High S in fuel higher SO 2 emissions More inorganic material in fuel (ash) higher PM2.5 emissions During near-complete combustion particulate matter mostly inorganic salts

19 Summary Advanced combustion technology can reduce CO and organic particle matter emissions Technology alone can t reduce emissions High quality fuel is necessary to further reduce SO 2, NO x, and inorganic PM emissions

20 Acknowledgments This study was funded by the New York State Energy Research and Development Authority (NYSERDA) under contract We want to thank David Dungate of ACT Bioenergy for his assistance in these studies 20

21 Questions?