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

2DTU Chemical Engineering, Technical University of Denmark 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

3DTU Chemical Engineering, Technical University of Denmark DTU Chemical Engineering: Lyngby

4DTU Chemical Engineering, Technical University of Denmark CHEC Research Center 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 Combustion and Harmful Emission Control (CHEC)

5DTU Chemical Engineering, Technical University of Denmark Development of CHEC 2000 Time 2010 Acidification Debate 1990 Coal Fluid Bed SO 2 NOx Bio-mass Alkali Corrosion- depositions Models Cement Waste Products Coatings Catalysis Gasification Pharma Minerals Merger Risø Systematic development of experimental methods and modeling tools Focus on Reaction Engineering, Transport processes New pilot

6DTU Chemical Engineering, Technical University of Denmark CHEC KDJ Combustion PGl Gasification UBH Fuel Pretreatment JA Diognostics SC Inorganics FF Catalysis AJ Products and Pharma SK Project coordination JBI Technique, Pilot facilities PAJ SDC Coordination WL CHEC Organization

7DTU Chemical Engineering, Technical University of Denmark 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).

8DTU Chemical Engineering, Technical University of Denmark Problems in firing of biomass

9DTU Chemical Engineering, Technical University of Denmark Main reason for the problems KCl Ash deposition Bed agglomeration Corrosion SCR deactivation PM2.5

10DTU Chemical Engineering, Technical University of Denmark K-S-Cl Chemistry in Straw-Fired Systems: K in straw KCl/KOH (g) K-Ca-silicates in bottom ash KCl/K 2 SO 4 nucleation/ heterogeneous condensation K 2 SO 4 (g) SO 2 Cl in straw HCl (g) Cl in bottom ash HCl emission KCl (g) SO 2 K 2 SO 4 (g) S in straw SO 2 (g) S in bottom ash SO 2 emission K 2 SO 4 (g) (+ HCl) KCl / KOH

11DTU Chemical Engineering, Technical University of Denmark Deposit Formation: Layered structure:  cm  > 0.7  100% KCl

12DTU Chemical Engineering, Technical University of Denmark 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), , 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 [~ 10 3 hours] exposed deposits (real chemistry, including chemical reaction sintering)

13DTU Chemical Engineering, Technical University of Denmark Measuring Campaigns at Grate Boilers Maribo-Sakskøbing boilerRudkøbing boiler Haslev boilerSlagelse boiler

14DTU Chemical Engineering, Technical University of Denmark Deposit Chemistry

15DTU Chemical Engineering, Technical University of Denmark 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

16DTU Chemical Engineering, Technical University of Denmark Corrosion

17DTU Chemical Engineering, Technical University of Denmark Corrosion induced by Deposit

18DTU Chemical Engineering, Technical University of Denmark Selective Cl-Corrosion: Influence of Methal Temperature Metal temperature

19DTU Chemical Engineering, Technical University of Denmark Aerosol (PM2.5) emissions

20DTU Chemical Engineering, Technical University of Denmark Main mechanisms for formation of aerosols during biomass combustion From van Loo and Koopejan (2002).

21DTU Chemical Engineering, Technical University of Denmark Aerosol in a Straw-Fired Boiler

22DTU Chemical Engineering, Technical University of Denmark Effect of Additives on Aerosol Mass Loading in a Straw-Fired Boiler: mg/Nm 3 d Aero, nm Ca-P S

23DTU Chemical Engineering, Technical University of Denmark Aerosol sampling: before SCR unit, T=350 o C Deposit probe measurement: location B, T= 780±20 o C Deposit probe measurement: location A, T= 1275±50 o C Aerosol emission in Avedøre unit 2 Damø et al. (2014), Wu et al. (2013)

24DTU Chemical Engineering, Technical University of Denmark 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)

25DTU Chemical Engineering, Technical University of Denmark Possible counter measures to reduce the risk of the problems + Co-combustion Pretreatment Boiler modification BoilerSCRESP BoilerESPSCR Additives +

26DTU Chemical Engineering, Technical University of Denmark Gasification

27DTU Chemical Engineering, Technical University of Denmark Two Stage Pilot Plant at Weiss A/S 1:1 1:10

DTU Chemical Engineering, Technical University of Denmark (LT-CFB) Pyroneer DONG Energy Asnæsværket Low Temperature Circulating Fluid Bed (LT-CFB)

29DTU Chemical Engineering, Technical University of Denmark 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

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