Viessmann Vitoflex 300-RF Technical Data Manual page 9

Vitoflex 300-RF Technical Data
Wood Fuel Requirements
Content limits for non-combustible substances
- No wood fuels may contain any foreign bodies, such
as pieces of metal, stones, masonry remnants or plastics.
The following limits (per lb/kg of dry fuel) of contained
non-combustible substances apply [ash analyzed at a
temperature of 1500°F (815°C)]:
Substance
Chlorine (Cl)
Sulphur (S)
Total Cl, S
Ash content, total
Alkali oxides in the ash (K2O and Na2O)
Sintering point of the ash
If fuel does not comply with these limits, there is a risk
of corrosion within the heat exchanger and early sintering
and melting of the ash which leads to:
- Shortened life of the heat exchanger
- Increased maintenance costs (firing, boiler door)
The maintenance instructions need to be complied with
in order to avoid a process, which will increasingly cause
damage to the boiler.
If maintenance instructions are not complied with the
following process may occur:
- Cinders change the airflow
- Temperature peaks
- More slag is produced
- More cinder builds up and changes the airflow more
This process leads to damage by overheating and may
affect refractory materials.
Additives in remnant and used wood have to be free of
heavy metals and halogen compounds.
(continued)
Limit
max. 300 ppm (300 mg/kg)
max. 1000 ppm (1000 mg/kg)
max. 1000 ppm (1000 mg/kg)
max. 0.25 oz/lb (15.0 g/kg)
max. 0.016 oz/lb (1.0 g/kg)
min. 1800°F (1000°C)
Other information
- Ash and cleaning:
Untreated wood without bark produces less than 0.5%
ash of the fuel mass supplied. All the specifications
regarding cleaning are based on untreated wood with
bark attached with an ash amount of 0.8% of the fuel
mass.
If the ash content is higher and/or the ash melting
point is lower, increased maintenance and/or cleaning
are required.
- Changing fuels:
A substantial change in fuel quality, such as bulk
density, water content, dust proportion or ash content
might require a manual correction of the firing
parameters (see Operating section).
General Information
Comparative value untreated forest wood
10 ppm (10 mg/kg)
120 ppm (120 mg/kg)
130 ppm (130 mg/kg)
0.08 oz/lb (5.0 g/kg)
0.006 oz/lb (0.35 g/kg)
approx. 2200°F (1200°C)
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