1 Principles of burning wood for heat generation
4
1.2 Principles of burning wood pellets for heat generation
What are pellets?
Wood pellets are made from 100 percent
natural wood residues. This raw material
is waste matter created by the timber
processing industry in large volumes
through planing or sawing.
Without binders, these fine−grained wood
residues are compressed and pelletised
under high pressure, i.e. they are pressed
into small cylindrical shapes.
The raw material is stored and
transported in absolutely dry conditions.
Absolutely dry conditions are equally
necessary for the storage by the system
user. Only these precautions can ensure
perfect and efficient combustion.
Fuel requirements
The wood pellets used for combustion in
Vitolig 300 must correspond to the
requirements of DIN 51731 or
ÖNORM 7135.
Requirements
Limits set by DIN 51731
Raw density (analogue to DIN 52182)
kg/dm
3
1.0 to 1.4
Water proportion
%
12
Ash (acc. to DIN 51718)
%
1.5
Calorific value (waf = free of water)
kJ/kg
17,500 to 19,500
Sulphur
%
0.08
Chlorine
%
0.03
Nitrogen
%
0.3
Arsenic
mg/kg
0.8
Cadmium
mg/kg
0.5
Chromium
mg/kg
8
Copper
mg/kg
5
Mercury
mg/kg
0.05
Lead
mg/kg
10
Zinc
mg/kg
100
Extractable organically bound halogen
(EOX)
mg/kg
3
For the combustion in Vitolig 300, use
pellets with a diameter of 6 mm, a length
from 5 to 30 mm (20 % up to 45 mm) with
a residual moisture content of 7 to 12 %.
Delivered forms
Currently, wood pellets are offered in
15 and 30 kg sacks, in bulk up to 1000 kg
on pallets and loose.
In their loose form, pellets are
transported by tanker and pumped into
the storage room via a hose system.
Careful handling of pellets ensures a low
dust proportion, a perfect fuel supply to
the boiler and a constant boiler output.
5822241 GB
