Data
sheet
Wood Fuels
Minimum Requirements / Information
Köb Holzheizsysteme GmbH, Flotzbachstr. 33, A-6922 Wolfurt, Tel. +43/5574/6770-0, Fax 65707, E-Mail: [email protected]
Subject to technical changes
1010-1
2009-03-01_GB
A prerequisite for approval is the express permission for such by the public authority responsible. For claims to
the warranty according to Section 11 of our General Terms and Conditions of Delivery, wood fuels have to meet
the following conditions. If those conditions are not met, then approval is possible with restrictions (warranty,
maintenance, operational safety) with a written statement by the manufacturer in reference to the facility.
1) Non-combustible substances contained
No wood fuels may contain any foreign bodies, such as pieces of metal, stones, masonry remnants or plastics. Nor
must the following limits (per kg of dry fuel) for non-combustible substances contained (ash analysed at a
temperature of 815°C) be exceeded or fallen short of:
Limit
Comparison
with
untreated
forest
wood
1.1) Chlorine Cl:
max. 300 mg/kg
10 mg/kg
1.2) Sulphur S:
max. 1000 mg/kg
120
mg/kg
1.3) Total Cl, S:
max. 1000 mg/kg
130 mg/kg
1.4) Ash content, total:
max. 15.0 g/kg
5.0 g/kg
1.5) Alkali oxides in the ash (K
2
O and Na
2
O): max. 1.0 g/kg
0.35 g/kg
1.6) Sintering point of the ash: min.
1000°C
approx.
1200°C
Consequence of substantial overstepping of limits (1.1, 1.2, 1.3, 1.5, 1.6):
a) Hot-gas corrosion in the heat exchanger
→
Special maintenance instructions for heat exchanger
→
Shortened service life of heat exchanger
b) Early sintering and melting of the ash
→
Special maintenance instructions for firing,
→
Increased maintenance costs (firing, boiler door)
If the maintenance instructions are not followed, a process will be created that builds up in a negative fashion with:
→
Cinders change the airflow
→
Temperature peaks
→
more slag
→
etc, until there is fast destruction of the
refractory materials
1.7) Additives in remnant and used wood:
Free of heavy metals and halogen compounds
2) Superfines & dust (wood particles smaller than 1.0 mm as per ÖNORM M 7133)
2.1) Without pre-dryer, max. 10.0% of the total mass; consequence of substantial overstepping of limit:
Temperature peaks
→
Slag formation
→
Even higher temperature
→
etc, to the point of destruction;
→
Special maintenance instructions for firing;
Elevated values are especially critical for remnant wood in combination with elevated values as per 1.1, 1.2
2.2) For forest wood chips with pre-dryer, max 4.0% of the total mass; consequence of substantial overstepping of
limit:
→
Moving the exhaust air lines
→
Special maintenance instructions for cleaning exhaust air line
3) Origin and treatment
3.1) Forest wood and plantation wood (complete trees and trunk wood untreated)
Mature wood from trunks and branches, untreated, chopped as billet wood or chips
3.2) Compressed wood, pellets (conforming to standards, such as: ÖNORM M 7135)
Untreated wood with limited bark content, compressed by machine and calibrated
3.2) Increased proportion of bark, tree cuttings from roadside trees (untreated)
Remnants from the forestry and sawmill industries or from conservation of the countryside (elevated ash
content).
3.3) Remnants from derived timber products
Usually a mixture of untreated and treated wood in the form of shavings from processing machinery and chips
from choppers that run slowly. In cases of elevated proportions of dust and/or limited storage volumes, these
shavings are compressed into briquettes.
3.4) Used wood
This is essentially untreated wood that has been used prior to its energetic utilisation (e.g. pallets). It is reduced
in size by shredders for thermal utilisation. The metal parts have to be removed afterwards (by magnetic
separators).
4) Particle size: adjustment of the conveyor augers
4.1) G30/G50 chips from untreated wood as per ÖNORM M 7133:
made by fast-running and cutting tools;
max. coarse fraction
with cross-section
and length
G 30
of 20%
max. 3 cm
2
max. 8.5 cm;
G 50
of 20%
max. 5 cm
2
max. 12 cm;
Required cross-sections of the loading: depends on the boiler output
:
up to 150 kW
up to 500 kW
from 500 kW
Conveyor auger
D
min. 12 cm;
min. 15 cm;
min. 20 cm
Drop cross-section
A
min. 175 cm
2
min. 300 cm
2
min. 600 cm
2
4.2) Chips not from the forest; origin as per 3.2, 3.3, 3.4; briquettes, origin as per 3.3
Size essentially as per ÖNORM M 7133 G50, additionally, however:
- Fraction of one-offs max. 5% with cross-section of max. 5 cm² up to a length of max. 16 cm
- Frayed surface by chopping tools (shredders) or slow-running choppers
- Briquettes, diameter max. D 60 mm (hydraulic compressors, pressure geared to loading system)
