Tag Archives: excess air coefficient

1257-1265 J. Bradna, J. Malaťák and D. Hájek
The properties of wheat straw combustion and use of fly ash as a soil amendment
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The properties of wheat straw combustion and use of fly ash as a soil amendment

J. Bradna, J. Malaťák* and D. Hájek

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Technological Equipment of Buildings, Kamýcká 129, CZ165 21 Prague, Czech Republic
*Correspondence: malatak@tf.czu.cz


Agriculture is one of possible producers of by-products suitable for energy purposes,

such as rapeseed and wheat straw. But on the other hand, not only thanks to the support of energy
from biomass grown specifically for this purpose, arable land is exposed to intense cultivation of
wide-row crops indirectly supporting soil erosion and nutrient elution. The issue of recycling ash
from biomass combustion on agricultural and forest land is very important to resolve. Experience
with this problem is found in countries in Northern Europe such as Finland or Sweden, as well as
in North America. Due to ash characteristics, it is considered a valuable soil component and a
potential replacement for conventional fertilizers.
Elemental analyses of samples from wheat straw pellets were followed by combustion and
emission measurements. The effects of temperature and volume of air in the combustion of wheat
straw was analysed, focusing on emission concentrations and the ash content. Effect of excess air
coefficient on the composition of end products after combustion was assessed in three modes
(small, optimum and high coefficient of excess air). During the measurements, the excess air
coefficient ranged between the values from 3.95 to 14.89. The average net calorific value of the
wheat straw samples was 15.55 MJ kg-1 in the original state. Mineral composition analysis of
solid combustion products, necessary for using these residues as a fertilizer or soil component,
was performed as well.

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