TY - JOUR
T1 - Release to the Gas Phase of Inorganic Elements during Wood Combustion. Part 2: Influence of Fuel Composition
AU - van Lith, Simone Cornelia
AU - Jensen, Peter Arendt
AU - Frandsen, Flemming
AU - Glarborg, Peter
PY - 2008
Y1 - 2008
N2 - Combustion of wood for heat and power production may cause problems such as ash deposition, corrosion,
and harmful emissions of gases and particulate matter. These problems are all directly related to the release
of inorganic elements (in particular Cl, S, K, Na, Zn, and Pb) from the fuel to the gas phase. The aims of this
study are to obtain quantitative data on the release of inorganic elements during wood combustion and to
investigate the influence of fuel composition. Quantitative release data were obtained by pyrolyzing and
subsequently combusting small samples of wood (~30 g) at various temperatures in the range of 500–1150
°C in a laboratory-scale tube reactor and by performing mass balance calculations based on the weight
measurements and chemical analyses of the wood fuels and the residual ash samples. Four wood fuels with
different ash contents and inorganic compositions were investigated, including wood chips from spruce and
beech, bark, and fiber board. The results showed a high release of Cl (~85–100%) and S (~50–70%) already
at 500 °C, so that only small variations in the release trends of Cl and S were seen between the different fuels
in the range of 500–1150 °C. The release of the alkali metals K and Na was, however, strongly dependent on
both the temperature and the fuel composition under the investigated conditions. The release of the heavy
metals Zn and Pb started around 500 °C and increased sharply to more than 85% at 850 °C in the case of
spruce, beech, and bark, and was therefore mainly dependent on the temperature. By comparing the data to
literature data, and by using tools such as scanning electron microscopy, chemical fractionation analysis, and
equilibrium calculations, a better understanding of the release mechanisms was obtained. Mechanisms for the
release of Cl, S, K, Na, Zn, and Pb during wood combustion are proposed.
AB - Combustion of wood for heat and power production may cause problems such as ash deposition, corrosion,
and harmful emissions of gases and particulate matter. These problems are all directly related to the release
of inorganic elements (in particular Cl, S, K, Na, Zn, and Pb) from the fuel to the gas phase. The aims of this
study are to obtain quantitative data on the release of inorganic elements during wood combustion and to
investigate the influence of fuel composition. Quantitative release data were obtained by pyrolyzing and
subsequently combusting small samples of wood (~30 g) at various temperatures in the range of 500–1150
°C in a laboratory-scale tube reactor and by performing mass balance calculations based on the weight
measurements and chemical analyses of the wood fuels and the residual ash samples. Four wood fuels with
different ash contents and inorganic compositions were investigated, including wood chips from spruce and
beech, bark, and fiber board. The results showed a high release of Cl (~85–100%) and S (~50–70%) already
at 500 °C, so that only small variations in the release trends of Cl and S were seen between the different fuels
in the range of 500–1150 °C. The release of the alkali metals K and Na was, however, strongly dependent on
both the temperature and the fuel composition under the investigated conditions. The release of the heavy
metals Zn and Pb started around 500 °C and increased sharply to more than 85% at 850 °C in the case of
spruce, beech, and bark, and was therefore mainly dependent on the temperature. By comparing the data to
literature data, and by using tools such as scanning electron microscopy, chemical fractionation analysis, and
equilibrium calculations, a better understanding of the release mechanisms was obtained. Mechanisms for the
release of Cl, S, K, Na, Zn, and Pb during wood combustion are proposed.
U2 - 10.1021/ef060613i
DO - 10.1021/ef060613i
M3 - Journal article
VL - 22
SP - 1598
EP - 1609
JO - Energy & Fuels
JF - Energy & Fuels
SN - 0887-0624
ER -