TITEL-FOLIE! INHALT! Overview on Technologies for! Biomass Combustion and! Emission Levels on Particulate Matter (PM)!

Transcription

1 TITEL-FOLIE! Expert Group on Techno-Economic Issues, EGTEI, Meeting Zurich ! Overview on Technologies for! Biomass Combustion and! Emission Levels on Particulate Matter (PM)! Thomas Nussbaumer " Verenum, Zurich! Lucerne University of Applied Sciences, Horw! SWITZERLAND" INHALT! 1.# Introduction of biomass cycle! 2.# Combustion fundamentals! 3.# Traditional one-stage combustion in stoves! 4.# Two-stage combustion for improved burnout" Wood boilers Pellets Automatic Boilers! 5.# Particle types and relevance! 6.# Particle conversion from stack to ambient! 7.# Emission factors and Emission Limit Values! 8.# Particle removal! 9.# Conclusions!

2 Sun & Biomass! EC (BC), COC! CO, VOC! Primary org. Aerosols POA! Secondary org. Aerosols SOA! h!! CC (salt) NO x! PIA! SIA! PM 10! CO 2! C fix! C! Ca, K, Cl, N! Ash! CaO, KCl! Environmental Impact: Life Cycle Assessment! high! Valuation of! green house effect! Eco indicator 95 rf [ ] base! low! PM! NO X! ESP! FF! Öl Gas Stückholz Holzschnitzel Holzpellets Oil Gas Log w. W. chips W. pellets*! F o s s i l W o o d f u e l s! [Kessler et al., 2000] *[Nussbaumer 2001]!

3 Environmental Impact: Life Cycle Assessment! [%]! NO X! 38.6%! PM 10! 36.5%! CO 2! 2.0%! SO X, NH 3, CH 4, NMVOC, primary energy, residues, and others! 22.9%! Total! 100%! [Kessler et al., 2000] (BUWAL Nr. 315)! INHALT! 1.# Introduction of biomass cycle! 2.# Combustion fundamentals! 3.# Traditional one-stage combustion in stoves! 4.# Two-stage combustion for improved burnout" Wood boilers Pellets Automatic Boilers! 5.# Particle types and relevance! 6.# Particle conversion from stack to ambient! 7.# Emission factors! 8.# Particle removal! 9.# Conclusions!

4 Diffusion " Flame! Flame Principles! Premixed" Flame! Kerze mit und ohne Russ" Gasfeuerzeug" Kerze in Glas: Wandtafel mit Molekülen: Neue Stoffe entstehen, Beweis: Kerze mit schwarzem Russ! Soot formation in the flame from HC!

5 PM 10! +h#$ > SOA$ COC = Condensable Organic Compounds! VOC = Volatile Organic Compounds! Solid Particles & Condens.! Gas phase emissions! Salts! Soot! COC! VOC! CO! CO 2! H 2 O! Particle Formation! sec. " <! " >! KCl! CO 3! Tar! CO! nucleation! K + Cl evaporation! CaCO 3 " -release! H 2 [2]! PAH! T >850 C [1]! T = C [1]! O 2 =0; (local) lack of O 2! prim. Tar! T <700 C [1]! C m H n! +O 2! +O 2! +O 2! C! +O 2! +O 2! -H 2 O! C x H y O z + w(h 2 O)! Wood! [1] : Evans and Milne, 1987! [2]: Jess, 1996! Wood Combustion with Air! % = Excess air ratio = Air/Air stoch = O 2 / O 2 min! CH 1.4 O % (O N 2 )! > Intermediate Products (CO, H 2, C m H n,...)!!!!!!!!co H 2 O + (% 1) O 2 + % 3.76 N 2!!!! MJ/kg!!

6 Correlation between CO and Hydrocarbon (HC)! HC [mg/m3] HC und CO in [mg/m3] bei 11 Vol% O2 Open a Chimney! b Log Wood Boiler! c Automatic Wood Chip Boiler (under stoker)! CO [mg/m3] [Nussbaumer 1989]! Requirements for Complete Burnout: T T T! Temperature Time Turbulence"!!!!!! (Mixing)! > 850 C! > 0.5 s! Re > 2300! (dry wood)" % < 2! -comb. chamber! -heat extraction! 2-stage Comb. with primary & secondary Air" Ventilator! Mixing zone!

7 T (%)! Influence of excess air on Temperature! dry wood! Excess air ratio! Reactions in Biomass Combustion! Gas and Tar: H2O, N2, + O2 (!1) Biomass T > 300 C (CHxOyNz) + (H2O) Devolatilization CO, H2, CH4, C2+ HCN, NHi,... O2! 0 NO X! CO, KW! K, Ca, Na, Cl, S..! T > 800 C Gasification of C C + CO2 < > 2 CO C + H2O < > CO + H2 C + 0,5 O2 < > CO KCl, K 2 SO 4, CaCO 3...! Char C heterogeneous reactions

8 INHALT! 1.# Introduction of biomass cycle! 2.# Combustion fundamentals! 3.# Traditional one-stage combustion in stoves! 4.# Two-stage combustion for improved burnout" Wood boilers Pellets Automatic Boilers! 5.# Particle types and relevance! 6.# Particle conversion from stack to ambient! 7.# Emission factors! 8.# Particle removal! 9.# Conclusions! 1-stage combustion! CO 2, H 2 O, O 2, N 2! CO, C x H y! + Air O 2 + N 2 $ at % > 1! Air! C H O!

9 CO (%)! Influence of Excess Air Lambda on CO! 1-stage combustion! Eta (%)! Limitations of 1-stage Combustion! Problem 6:" Flame Quenching! Problem 5:" Heat Extraction! in Combustion Zone! Problem 4:" Gas Leakage! Problem 3:" Air Leakage! Problem 2:" Mixing Air + Gas! Problem 1:" Air Distribution!

10 1-stage Combustion Wood Stove! Eta < 60%! 1-stage Combustion with Combustion Chamber! Air!

11 INHALT! 1.# Introduction of biomass cycle! 2.# Combustion fundamentals! 3.# Traditional one-stage combustion in stoves! 4.# Two-stage combustion for improved burnout" Wood boilers Pellets Automatic Boilers! 5.# Particle types and relevance! 6.# Particle conversion from stack to ambient! 7.# Emission factors! 8.# Particle removal! 9.# Conclusions! 2-stage Combustion with forced Downdraft! Wood: C Hoval! H O! Hoval! + Air % < 1! O 2 + N 2 $ CO, H 2, C x H y " CO 2, N 2! + Air % > 1! O 2 + N 2 $ CO 2, H 2 O, N 2! Eta > 90% But: Heat Storage Tank needed!!

12 2-stage Combustion with forced Downdraft! Fröling S4 Turbo 28 kw, Foto: R. Mettler 2008! Premixed flame! 2-stage Combustion with Downdraft and Grate! Schmid!

13 Central heating with wood boiler and heat storage tank! Tiba/Energie Control! (ÖKOcentro)! Wood stove with primary air! Manual furnace w. 2-stage combustion! Autom. furnace1990! Autom. furnace 2000, Pellet furnace! Control! CO (%): Influence of Excess Air Lambda on CO!

14 CO (%)! 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! Pellet Boiler with Grate for periodic Ash Removal! Liebi LNC AG (Switzerland)!

15 Pellet Boiler with Automatic Ignition! Hargassner (Austria)! Eta > 90%! Under Stoker Boiler Grate Boiler! w $ 10% 50%, a < 5%! w $ 10% 55%, a < 50%! 200 kw... 2 MW 400 kw... >10 MW!

16 Under Stoker Boiler Grate Boiler! w $ 10% 55%, a < 50%! 200 kw... 2 MW 400 kw... >10 MW! Schmid (Switzerland)! CFD: 1. Strömungsvisualiserung: Qualitative Bewertung!

17 Feuerungen Müller und Schmid! Müller! Schmid! 100 kw 2 MW!! > MW " mit Zyklon! mit Feinstaubabscheider" CH > 500 kw m. FA! Water cooled grate & dust burner MW! Vyncke!

18 NO+NH 2! "N 2 +H 2 O! [Keller & Nussbaumer, 1994]! [Salzmann & Nussbaumer, 2001]! Air staging and fuel staging! Vyncke!

19 Fluidized Bed Combustion! Stationary (SFB)! MW! Circulating (CFB)! MW! Bed material! Cooling! Lurgi! Ahlstom! INHALT! 1.# Introduction of biomass cycle! 2.# Combustion fundamentals! 3.# Traditional one-stage combustion in stoves! 4.# Two-stage combustion for improved burnout" Wood boilers Pellets Automatic Boilers! 5.# Particle types and relevance! 6.# Particle conversion from stack to ambient! 7.# Emission factors! 8.# Particle removal! 9.# Conclusions!

20 Air Pollution and Mortality in Six U.S. Cities! Relative Mortality [ ]! Portage = 1! PM 2.5 [µg/m 3 ]! P = Portage, T = Topeka, W = Watertown, L = St. Louis, H = Harriman, S = Steubenville.! Dockery et al. New England J. Med. Vol 329 (1993): Particle Properties! Flaming Combustion! lack of O 2 in the flame! Mix! T and O 2 good! Pyrolysis! T low at start or high O 2! O 2 lack gas. or fl. ext.! View! PM! Soot! Salts + Soot! Salts! COC! Composition! EC / BC! chemical / optical " C/H > 6...8! CC + Minerals! carbonate C + inorg. M! OC! = TC EC CC" C/H < 2! Colour! black! grey! white! brown none! Health effect!! Climate effect! absorbs light and" heats atmosphere *! scatters light and" cools surface! weakly absorbs! and scatters! * [T. Bond, Testimony, US House of Repr ]: BC = 2000 x CO 2 for 20 y! [ICCT, June 2009]: BC responsible of 0.34 Wm 2 of total 1.6 Wm 2!