AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Dynamic Changes in the Aerosol Composition and Concentration During Different Burning Phases of Wood Combustion
MICHAEL ELSASSER, Christian Busch, Jürgen Orasche, Hans Hartmann, Jürgen Schnelle-Kreis, Ralf Zimmermann, Helmholtz Zentrum München
Abstract Number: 107 Working Group: Combustion
Abstract Different on- and off-line mass spectrometry-based methods were applied to investigate changes in aerosol gas-phase and particle-phase composition during wood combustion in the different phases of the burning process. The experiments were carried out with a logwood boiler and a stove at the Technology and Support Centre (TFZ) for renewable resources in Straubing, Germany. Different fuel types (spruce and beech) and burning conditions (normal, overloaded feed, oxygen deficiency) were investigated. The aerosol particle phase of the non-refractory compounds was analysed by a High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS, Aerodyne Research Inc.). Together with a Photo Ionisation (PI) Time-of-Flight Mass Spectrometer (ToF-MS), which detects selective aromatic organic compounds in the gas phase by Resonance Enhanced Multi Photon Ionisation (REMPI), it provides a useful tool to measure the dynamic of wood combustion.
This dynamic could be described and reflected in four different burning phases, during which the aerosol compounds and concentration changed strongly. For example, the first phase, which is of pyrolysic nature, shows the highest concentrations of organic mass, mass-to-charge ratio (m/z) 60 and guaiacol. The following “harsh combustion phase” provides an increase of the phenolic compounds in the flue gas, indicating the breakdown of the lignin backbone of the wood structure. Additionally, the contribution of organic mass to total non-refractory mass during these phases decreases from 99% to 91%. The wood combustion marker signal at m/z 60 also decreases. The subsequent “stable flaming phase” has the highest relative amount of sulphate and chloride, so the impact of inorganic compounds increases like in the second phase. The start of the char burnout is indicated by an increase of the carbon monoxide concentration in the gas phase. This contribution provides an overview of the impact of the dynamic phases of wood combustion. Additionally, it shows that burning conditions can significantly change the emission.