HDG Compact 25, Руководство по эксплуатации

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3 Mode of operation – Fuel quality requirements
26
Medium wood chips with a particle size of up to 45 mm (P45S) are
used in larger systems, but may however also still be suitable for
small systems depending on the diameter of the conveyor auger.
Oversized pieces (end pieces) could lead to malfunctions during
system operation. Higher proportions of finer content (dust) can lead
to high emissions and ejection of glowing particles.
Wood chips from category P45S HDG Compact 25 - 80 - as described
above - can be used as fuel in all HDG wood chip boilers. For the HDG
Compact 25/35, the maximum length of oversized particles is limited
to 85 mm and 120 mm for the HDG Compact 45/50/65/80.
W
ATER CONTENT
When selecting fuel, note that the calorific value of the wood is pri-
marily dependent on the water content. The more water contained
in the wood, the smaller the calorific value, since the water vaporises
in the course of the burning process and thereby consumes heat.
This results in lower efficiency and thereby leads to greater wood
consumption. Increasing moisture in the fuel material also causes re-
duced efficiency of the boiler, greater amounts of ash and smoke, as
well as making it increasingly unfit for storage.
The maximum permissible water content of the wood chips is 20 %
(M20) for the HDG Compact 25/35 and 25 % (M25) for the HDG Com-
pact 45/50/65/80 and complies with the property class A1. The water
content of the wood chips may not be under 10 % (M10) as a higher
aerosol formation causes a higher level of dust.
For technical considerations, a representative calorific value is se-
lected depending on water content. For burning that is both eco-
nomical and low on emissions, the calorific value should not be less
than 4 kWh/kg.
A
SH CONTENT
For environmentally-friendly operation of the wood chip boiler, a low
ash content is required. At the same time, this also minimizes the
content of elements critical for combustion. Inorganic substances
which are aerosol forming, such as potassium, chlorine or sodium are
the main factors determining dust emissions in combustion. These
elements are predominantly found in the needles, leaves and bark of
the tree. Well-prepared, pure wood types, such as delimbed energy
wood without needles, leaves and only a minimal proportion of bark,
have the lowest content of elements critical for combustion. They are
therefore recommended for use in residential boiler systems.
The ideal ash content is a maximum of 1.0% by weight (A1.0) and this
complies with property class A1. When using wood chips with a
higher ash content (property class A2 and B1/2) secondary measures
Water content Moisture Calorific value
Relative wood
consumption
10.0 % 11.1 % 4.6 kWh/kg 87 %
20.0 % 25.0 % 4.0 kWh/kg 100 %
26.0 % 35.0 % 3.7 kWh/kg 110 %
30.0 % 42.9 % 3.4 kWh/kg 120 %
Table 3/4 - Calorific value depending on water content