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Investigation of primary and secondary aerosols from wood combustion with a high resolution time of flight aerosol mass spectrometer

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Investigation of primary and secondary aerosols from wood combustion with a high resolution time of flight aerosol mass spectrometer Maarten Heringa – PowerPoint PPT presentation

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Title: Investigation of primary and secondary aerosols from wood combustion with a high resolution time of flight aerosol mass spectrometer


1
Investigation of primary and secondary aerosols
from wood combustion with a high resolution time
of flight aerosol mass spectrometer
Maarten Heringa Laboratory of Atmospheric
Chemistry Paul Scherrer Institut,
Switzerland Gothenburg 23-06-2008
2
Why are we interested in wood burning?
  • Biomass has the potential to become the worlds
    largest and most sustainable renewable energy
    source. (2004 Survey of Energy Resources World
    Energy Council)
  • Three billion people use small-scale wood fueled
    appliances that are both inefficient and highly
    polluting. (2007 Survey of Energy Resources World
    Energy Council)

3
Examples of wood burning
4
Wood burning in Roveredo Switzerland
Wood is used as fuel for 75 of the domestic
heating installations in Roveredo Switzerland1
1(Alfarra et al., 2007 Environ. Sci. Technol)
5
Wood combustion
Cellulose, hemicellulose and lignin are the main
constituents of wood
Incomplete combustion C,H,O O2 ? CO2 H2O
CO CxHyOz N2 impurities NOx salts
minerals BC
Complete combustion C,H,O O2 ? CO2 H2O N2
impurities NOx salts minerals
6
Wood combustion markers
Levoglucosan has been reported as major
constituent of fine particulate emissions2 and
its prominent fragment at m/z 60 has been used as
marker ion3
Fragment m/z 60 is not unique for levoglucosan!
2(Reid et al., 2005 Atmos. Chem. Phys)
3(Alfarra et al., 2007 Environ. Sci. Technol)
7
Objectives
  • Characterization of primary emissions
  • Log wood burners
  • Automatic pellet burners
  • Wood burning markers m/z 60, 73 and 137
  • Investigation of the stability of wood burning
    markers m/z 60, 73 and 137
  • Investigation of the SOA formation potential of
    wood burning emissions in the PSI smog chamber

8
HR-ToF-AMS
Q-AMS
TOF Spectrometer
Quadrupole Mass Spectrometer
Flow 2.2 cm3/sec
Flow 1.3 cm3/sec
Critical orifice (100 µm)
Critical orifice (130 µm)
Chopper (150 Hz)
Thermal Vaporization (600C) and Electron
Ionization (70 eV)

e
TOF Region
Aerodynamic Lens (2 Torr)
Particle Inlet (1 atm)
Turbo Pump (1E-3 Torr)
Turbo Pump (1E-5 Torr)
Turbo Pump (1E-8 Torr)
DETECTION CHAMBER
AERODYNAMIC SIZING CHAMBER
(Jayne et al., 2000 De Carlo et al., 2006)
9
Primary emissions
Pellet burner 80 (7.2 kW), 1.46 kg/h
Log wood burner 0.5kg softwood 2 x 2.7kg beech
10
Scheme of the setup
CVS
Clean air generator
Excess air
Excess air
Dilution ratio 150x
Heated Diluter (150C)
Diluter
11
Dilution ratio calculations
12
Pellet burner
13
Start automatic burner
Start peak
Wood burning markers m/z 60, 73, 137
14
Stable burning automatic burner
Stable burning
Wood burning markers m/z 60, 73, 137
15
Reproducibility of a log wood burner
2.7kg of beech cut to a standard size and weight
(Weimer et al., 2008 Geophysical Research)
16
Log wood burner
17
First load of beech
18
End of the fire
19
Smog chamber setup
CO,CO2,NOx,O3
Excess air
Clean air generator
Heated line (150C)
18
CO2
Heated Diluter
4 L/min
20
Smog chamber experiment
  • Humidification of the chamber
  • Background measurements
  • Start the burner
  • Filling the chamber
  • Measurement
  • primary emissions
  • Lights on

21
Organics and black carbon
22
Wood burning markers
23
Oxidation
24
Conclusions
  • Automatic pellet burners produce high
    concentrations of organics during the ignition
  • During stable burning the spectrum of the
    organics is dominated by m/z 44 which is the
    dominant signal of OOA
  • Log wood burners show large variations in
    concentration between runs and during a burning
    cycle
  • The wood burning marker at m/z 60
  • is mainly formed during the start
  • consist of one molecular formula
  • is stable for gt 5 hours
  • Oxidation of the gas phase emissions of the
    tested log wood burner increased the organic
    aerosol mass with a factor of 2-3

25
Take home
  • Burning automatic pellet burners emit less
    organics during stable burning than log wood
    burners. Nevertheless, high concentrations of
    organics are emitted during the ignition.
  • Log wood burners show large variations in
    emissions between runs and during a single
    burning cycle. The spectral changes during the
    burning cycle makes it more difficult to identify
    a representative source profile.
  • A particle filter can reduce the primary aerosol
    emissions. However, due to SOA formation, only a
    reduction of 25-40 can be established (for a
    particle filter with 80 efficiency)

26
Thanks to
Roberto Chirico, Peter DeCarlo, Agnes Richard,
Torsten Tritscher, Marco Steiger, Rami
Alfarra, Andre Prévôt Urs Baltensperger
Nickolas Meyer Heinz Burtcher
Michael Sattler Christian Gaegauf
Thank you for your attention
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