Biomass Combustion in Europe Thomas Nussbaumer Lucerne University of Applied Sciences 6048 Horw Verenum R&D in Bioenergy 8006 Zurich SWITZERLAND EMEP, Albany (NY), USA 11.16.07 Verenum
Biomass Combustion in Europe 1. Introduction 2. Fundamentals 3. One-stage combustion 4. Two-stage combustion for high burnout a) Log wood, b) Pellets c) Automatic Boilers 5. Particle emissions 6. NO X emissions 7. Other pollutants 8. Conclusions Verenum
The fossil Period: A Peak in History Verenum
1. Heat 2. Power 3. Transport ? ! Verenum
Carbon C cle for Bioener CO + C org + C el KCl, CaCO 3 CO 2 h ν NO x +N 2 C, Ca, K, N Ca, K, ... Verenum
Sustainability Requirements for Bioenergy 1. Sustainable biomass production: No deforestation ! 2. Social aspects: Biomass for food first, no competition 3. Ecological aspects: Acceptable air pollution Verenum
Biomass Combustion in Europe 1. Introduction 2. Fundamentals 3. One-stage combustion 4. Two-stage combustion for high burnout a) Log wood, b) Pellets c) Automatic Boilers 5. Particle emissions 6. NO X emissions 7. Other pollutants 8. Conclusions Verenum
Flame Principles Premixed Diffusion Flame Flame Kerze mit und ohne Russ Verenum Gasfeuerzeug Kerze in Glas: Wandtafel mit Molekülen: Neue Stoffe entstehen, Beweis: Kerze mit schwarzem Russ
Wood Combustion with Air λ = Excess air ratio = Air/Air stoch = O 2 / O 2 min CH 1.4 O 0.7 + λ ( O 2 + 3.76 N 2 ) –> Intermediate Products (CO, H 2 , C m H n ,...) CO 2 + 0.7 H 2 O + ( λ –1) O 2 + λ 3.76 N 2 + 18.3 MJ/kg Verenum
Correlation between CO and Hydrocarbon (HC) HC und CO in [mg/m3] bei 11 Vol% O2 10000 Open Chimney a HC [mg/m3] b Log Wood Boiler 1000 c Automatic Wood Chip 100 Boiler (under stoker) 10 1 10 100 1000 10000 100000 [mg/m3] CO [Nussbaumer 1989] Verenum
Requirements for Complete Burnout: T T T Temperature – Time – Turbulence (Mixing) > 850°C > 0.5 s Re > 2300 -co mb. chamber 2-stage Comb. (dry wood ) with primary & -he at extraction secondary Air < 2 λ Ventilator Mixing zone Verenum
T ( λ ) T ( λ ) Influence of excess air on Temperature dry wood Excess air ratio Verenum
Group of Pollutants from Wood Combustion CH 1.4 O 0.7 + O 2 → CO 2 + 0.7 H 2 O CO, C X H Y , C org , soot ... → 1 PM N NO X → 2 K, Ca, Na, Cl , S.. → KCl, K 2 SO 4 , CaCO 3 ... 3 Verenum
Biomass Combustion in Euro e 1. Introduction 2. Fundamentals 3. One-stage combustion 4. Two-stage combustion for high burnout a) Log wood, b) Pellets c) Automatic Boilers 5. Particle emissions 6. NO X emissions 7. Other pollutants 8. Conclusions Verenum
1-stage combustion CO 2 , H 2 O, O 2 , N 2 CO, C x H y + Air O 2 + N 2 at λ > 1 Air C H O Verenum
CO ( λ ) Influence of Excess Air Lambda on CO 1-stage combustion Eta ( λ ) Verenum
Limitations of 1-stage Combustion Problem 6: Problem 4: Flame Gas Leakage Quenching Problem 3: Problem 5: Air Leakage Heat Extraction Problem 2: in Combustion Mixing Air + Gas Zone Problem 1: Air Distribution Verenum
1-stage Combustion Wood Stove Eta < 60% Verenum
Organic PM / Tar Soot [Kägi & Schmatloch 2002] Heuberger in Verenum [Klippel & Nussbaumer 2007]
1-stage Combustion with Combustion Chamber Air Verenum
Biomass Combustion in Euro e 1. Introduction 2. Fundamentals 3. One-stage combustion 4. Two-stage combustion for high burnout a) Log wood, b) Pellets c) Automatic Boilers 5. Particle emissions 6. NO X emissions 7. Other pollutants 8. Conclusions Verenum
2-stage Combustion with forced Downdraft Wood: C H O Hoval Hoval + Air λ < 1 O 2 + N 2 CO, H 2 , C x H y CO 2 , N 2 + Air λ > 1 O 2 + N 2 CO 2 , H 2 O, N 2 Eta > 90% – Heat Storage Verenum
2-stage Combustion with forced Downdraft Premixed flame Verenum
2-stage Combustion with Downdraft and Grate Schmid Verenum
CO ( λ ) Influence of Excess Air Lambda on CO Downdraft boilers are sensitive for channelling and bridging –> not suited for fine wood (dust) or very large logs ! Simple wood stove Furnace with 2-stage combustion Autom. furnace 1990 Autom. furnace 2000 Pellet furnace Combustion control Verenum
Detail of stove 3 Tiba (Switzerland) Prototype 2-stage Stove Verenum
2-stage Combustion Stove in Operation Verenum
Pellet Boiler with Automatic Ignition Eta > 90% Hargassner (Austria) Verenum
Pellet Boiler with Grate for periodic Ash Removal Liebi LNC AG (Switzerland) Verenum
Under Stoker Boiler Grate Boiler w ≈ 10% – 50%, a < 5% w ≈ 10% – 55%, a < 50% 200 kW ... 2 MW 400 kW ... >10 MW Verenum
Under Stoker Boiler Grate Boiler w ≈ 10% – 55%, a < 50% 200 kW ... 2 MW 400 kW ... >10 MW Schmid (Switzerland) Verenum
District Heating 6.4 MW Schmid AG, Wilderswil, Interlaken (Victoria-Jungfrau) Verenum
Burnout quality T T T: Time, Temp., Turbulence NO+NH 2 • Mixing limits burnout → N 2 +H 2 O • Excess air low (1.5) and accurately controlled [Bruch & Nussbaumer, 1998] Verenum
Combustion Modeling [Bruch & Nussbaumer, 1998] Verenum Verenum
Fluid Dynamics: Model Laser Camera [Brzovic, Nussbaumer & Baillifard, 2007] Verenum
Biomass Combustion in Europe 1. Introduction 2. Fundamentals 3. One-stage combustion 4. Two-stage combustion for high burnout a) Log wood, b) Pellets c) Automatic Boilers 5. Particle emissions 6. NO X emissions 7. Other pollutants 8. Conclusions Verenum
Particle Measurement Verenum
Ver leich der Toxizität verschiedener Partikel Wood stove with bad operation Wood soot and tar ( condens.) Toxicity = 10 Diesel soot Diesel car without particle filter Toxicity = 1 Automatic wood furnace Ash particles = salts 6 7 5 8 Toxicity < 0,2 4 1 2 3 8 Verenum
Results of Cytotoxicity Tests Cell Survival 100 Inorganic particles (AWC) 90 Similar for empty filter ! 80 70 Survival [%] Diesel soot 60 50 40 30 20 10 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Particle concentration in cell medium [ � g/ml] Verenum
Results of Cytotoxicity Tests Cell Survival 100 90 80 Diesel soot 70 Survival [%] 60 50 particles from 40 bad combustion conditions in a 30 small wood 20 stove 10 0 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Particle concentration in cell medium [ � g/ml] Verenum
Origin and detection of PM from biomass combustion Filter at Impinger Origin Form 180°C after filter (VDI) (EPA) Salts Ash + (+) solid Soot Incom- plete com- bustion – + Tar liquid Verenum
Typical Emissions (mg/m 3 @ 13 Vol.-% O 2 ) Automatic Ideally Typically Badly mg/MJ = wood operated operated operated 0.68 x mg/m 3 combustion wood stove wood stove wood stove @ 13 Vol.-% O 2 Salts 100 < 20 Soot < 5 < 20 100 5 000 Tar < 5 < 5 400 10 000 Total PM < 100 < 50 500 15 000 Verenum
Particle precipitation Pre dedusting > 5 µm Fine particle removal < 10 ... < 0,01 µm Cyclone Electrostatic Precipitator (ESP) Fabric filter (FF) – + + Raw gas Clean gas Condensation! C-content < 2% Verenum
Particle precipitation Pre dedusting > 5 µm Fine particle removal < 10 ... < 0,01 µm Cyclone Electrostatic Precipitator (ESP) Fabric filter (FF) – + + Aerob-Beth Scheuch Scheuch Raw gas Clean gas Condensation! C-content < 2% Verenum
Biomass Combustion in Europe 1. Introduction 2. Fundamentals 3. One-stage combustion 4. Two-stage combustion for high burnout a) Log wood, b) Pellets c) Automatic Boilers 5. Particle emissions 6. NO X emissions 7. Other pollutants 8. Conclusions Verenum
Conversion of Fuel-Nitrogen O 2 NO Temp N HCN in Fuel NH 3 -NH 2 N 2 O 2 Verenum
λ = 0.7 NO+NH 2 → N 2 +H 2 O [Keller & Nussbaumer, 1994] [Salzmann & Nussbaumer , 2001] Verenum
Air staging Air staging and Fuel staging Reduction zone Müller [Salzmann & Nussbaumer, 2001] [Fastenaekels & Nussbaumer, 2002] Verenum Vyncke
Biomass Combustion in Europe 1. Introduction 2. Fundamentals 3. One-stage combustion 4. Two-stage combustion for high burnout a) Log wood, b) Pellets c) Automatic Boilers 5. Particle emissions 6. NO X emissions 7. Other pollutants 8. Conclusions Verenum
PCDD/F as a function of carbon burnout [Oehme et al. 1987] Verenum
Biomass Combustion in Euro e 1. Introduction 2. Fundamentals 3. One-stage combustion 4. Two-stage combustion for high burnout a) Log wood, b) Pellets c) Automatic Boilers 5. Particle emissions 6. NO X emissions 7. Other pollutants 8. Conclusions Verenum
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