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Technical considerations on biomass fired boilers for heat and power - Research in CHEC, DTU

Technical considerations on biomass fired boilers for heat and power - Research in CHEC, DTU. Weigang Lin CHEC Research C enter Department of Chemical and Biochemical Engineering Technical University of Denmark. Outline.

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Technical considerations on biomass fired boilers for heat and power - Research in CHEC, DTU

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  1. Technical considerations on biomass fired boilers for heat and power - Research in CHEC, DTU Weigang Lin CHEC Research Center Department of Chemical and Biochemical Engineering Technical University of Denmark

  2. Outline • Brief introduction of DTU Chemical Engineering and CHEC research center • Problems in biomass fired boilers • Fundamental studies • Deposit • Corrosion • Aerosol emissions • Counter measures • Gasification • Concluding remarks

  3. DTU Chemical Engineering: Lyngby

  4. CHEC Research Center Combustion and Harmful Emission Control (CHEC) • New and Fundamental knowledge on • High Temperature Processes • Formation and Reduction of Harmful Components and Particulates • Catalysis and Chemical Product Design • To assist enterprises and governmental organisations • To train engineers and researchers • To catalyze international cooperation

  5. Development of CHEC Merger Risø New pilot Acidification Debate Time 1990 2000 2010 Coal Fluid Bed SO2 NOx Bio-mass Alkali Corrosion-depositions Models Cement Waste Products Coatings Catalysis Gasification Pharma Minerals Systematic development of experimental methods and modeling tools Focus on Reaction Engineering, Transport processes

  6. CHEC Organization

  7. New MSc Programme Started in China A full MSc programme on chemical and Biochemical Engineering, with focus on Biomass, is launched in Beijing, China. The programme offers Danish and Chinese students the possibility of obtaining a dual degree from DTU and the University of Chinese Academy of Sciences (UCAS).

  8. Problems in firing of biomass

  9. Main reason for the problems PM2.5 KCl Corrosion Ash deposition Bed agglomeration SCR deactivation

  10. SO2 (g) KCl/K2SO4 nucleation/ heterogeneous condensation SO2 emission HCl emission HCl (g) KCl/KOH (g) SO2 KCl / KOH Cl in straw KCl (g) S in straw SO2 K2SO4 (g) (+ HCl) K2SO4 (g) K in straw K2SO4 (g) Cl in bottom ash S in bottom ash K-Ca-silicates in bottom ash K-S-Cl Chemistry in Straw-Fired Systems:

  11. Deposit Formation: Layered structure:  cm  > 0.7 100% KCl

  12. Measuring Campaigns at Grate Boilers:Fly Ash and Deposit Chemistry • Haslev and Slagelse CHPs (probe), 1994 • Rudkøbing CHP (probe + mature), 1995 • Masnedø CHP (probe + mature), 1996-1997, 2000-2002 • Maribo-Sakskøbing CHP (mature), 2001, 2004 • Probe deposits: short term [~ 2-10 hours] exposure of cooled probes (finger print chemistry) • Mature deposits: In-boiler, long term [~ 103 hours] exposed deposits (real chemistry, including chemical reaction sintering)

  13. Measuring Campaigns at Grate Boilers Maribo-Sakskøbing boiler Rudkøbing boiler Haslev boiler Slagelse boiler

  14. Deposit Chemistry

  15. Boiler wall Probe Superheaters CCD camera Flue gas flow • New, advanced probe: • Heat transfer • Mass of deposits • Temperatures (flue gas and probe) • Video – visible and IR After 3 hr

  16. Corrosion

  17. Corrosion induced by Deposit

  18. Selective Cl-Corrosion: Influence of Methal Temperature Metal temperature

  19. Aerosol (PM2.5) emissions

  20. Main mechanisms for formation of aerosols during biomass combustion From van Loo and Koopejan (2002).

  21. Aerosol in a Straw-Fired Boiler

  22. Effect of Additives on Aerosol Mass Loading in a Straw-Fired Boiler: mg/Nm3 Ca-P dAero, nm mg/Nm3 S dAero, nm

  23. Aerosol emission in Avedøre unit 2 • Aerosol sampling: before SCR unit, T=350oC • Deposit probe measurement: location B, T=780±20 oC • Deposit probe measurement: location A, T=1275±50 oC Damø et al. (2014), Wu et al. (2013)

  24. Mass-based particle size distribution of aerosols • Significant reduction of submicron aerosol formation with addition of coal fly ash • Similar effect for the addition of 6 ton/h and 3 ton/h coal fly ash Damø et al. (2014)

  25. Possible counter measures to reduce the risk of the problems Boiler SCR ESP + Boiler ESP SCR Boiler modification Co-combustion + Additives Pretreatment

  26. Gasification

  27. Two Stage Pilot Plant at Weiss A/S 1:1 1:10

  28. (LT-CFB) PyroneerDONG Energy Asnæsværket Low Temperature Circulating Fluid Bed (LT-CFB)

  29. Concluding remarks • Cl, K and S cause severe operational problems in biomass fired boilers for heat and power production, especially deposition, corrosion, agglomeration and aerosol emissions • Co-firing biomass and coal can significantly reduce the operational problems • Application of right additives may be the other solution • Biomass to power through gasification

  30. Thanks for the Attention

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