KOB PYROT - Minimum Wood Fuel Requirements; Content; Non-Wood Biomass Fuels; Wood Fuel Regulations and Standards

1.3 Minimum wood fuel requirements
Content
When procuring wood for combustion, it is important to ensure that
foreign matter (e.g. stones, metal parts, brick fragments, plastics, etc.)
is avoided. This changes the composition of the fuel and therefore the
critical parameters of the combustion process.
The values must not exceed or fall below the following limits (per kg of
dry fuel) for the non-combustible content (ash at an analysis temper-
ature of 815 °C):
Limit Comparison with natural wood from forests
Chlorine Cl mg/kg max. 300 10
Sulphur S mg/kg max. 1000 120
Total Cl, S mg/kg max. 1000 130
Ash content total g/kg max. 15.0 5.0
Alkali oxides in the ash (K
2
O and Na
2
O) g/kg max. 1.0 0.35
SB start of ash sintering °C min. 1000 approx. 1200
A consequence of exceeding the above limits is a shortened service
life of the combustion chamber and wood boiler. This also means that
maintenance work is increased and service intervals are reduced.
The proportion of dust-like and fine-grain materials should also be
minimised (in accordance with ÖNORM M 7133).
Non-wood biomass fuels
Non-wood biomass fuels, such as needles, leaves, grain, straw, husks,
fruit kernels, etc., are generally unsuitable as a fuel for trouble-free
operation and are therefore not permissible.
In some cases, the fuel properties (essential composition, ash sinter-
ing point, etc.) differ considerably from those of wood. Combustion in
a Pyrot may lead to impairment of the combustion characteristics and
to greater stress on the fireclay lining and the heat exchanger surfaces.
Warranty claims can therefore only be asserted when using permissi-
ble fuels.
Wood fuel regulations and standards
Germany Revised first version of BImSchV dated 22.03.2010
Austria FAV dated 18.11.1997 "Ordinance for Combustion Systems" § 3.(1) 3. Solid fuels
Switzerland Clean air regulations LRV dated 16.12.1985 (as of 28.03.2000)
ÖNORM M 7133 Woodchips for energy purposes (1998)
EN 303-5 Boilers for solid fuels, table 8 "Test fuels"
CEN/TS 14961 Solid biofuels
Principles of wood combustion
(cont.)
PYROT
7
5822 516 GB
1