KOB PYROT - Principles of Wood Combustion; Principles of Pellet Combustion for Generating Heat; What Are Wood Pellets; Fuel Requirements

1.1 Principles of pellet combustion for generating heat
What are wood pellets?
Wood pellets are made from 100% natural wood remnants. This raw material is waste matter created by the wood industry in large volumes
through planing or sawing. Wood remnants are compressed under high pressure and formed into pellets, i.e. pressed into a cylindrical shape.
The raw material is stored and transported in completely dry conditions. The system user should also ensure completely dry storage conditions.
Optimum and effective combustion can only be ensured under these conditions.
Fuel requirements
For combustion in the PYROT, use pellets with a diameter of 6 mm, a
length from 5 to 30 mm (20 % up to 45 mm) with a maximum residual
moisture content of 10 %.
The wood pellets used for combustion in the PYROT must correspond
to the requirements of DINplus or ÖNORM M 7135.
Requirements DINplus ÖNORM
M 7135
Abrasion resistance %
≤ 2.3 ≤ 2.3
Raw density
kg/dm
3
≥ 1.12 ≥ 1.12
Water content %
≤ 10 ≤ 10
Ash content %
≤ 0.5 ≤ 0.5
Net calorific value MJ/kg
≥ 18 ≥ 18
kWh/kg
≥ 5 ≥ 5
Sulphur content %
≤ 0.04 ≤ 0.04
Chlorine content %
≤ 0.02 ≤ 0.02
Nitrogen content %
≤ 0.3 ≤ 0.3
Compression additive %
≤ 2 ≤ 2
Ext. production control yes –
Quality characteristics
High quality pellets:
■ Smooth shiny surface
■ Uniform length
■ Low proportion of dust
■ Sink in water
Low quality pellets:
■ Cracked rough surface
■ Severely varying length
■ High proportion of dust
■ Float in water
Forms of delivery
In their loose form, pellets are transported by silo tanker and pumped
into the storage room via a hose system.
Careful handling of pellets enables a low proportion of dust, trouble-
free boiler charging and a constant wood boiler output.
1.2 Principles of woodchip combustion for generating heat
What are woodchips?
Woodchips are made from 100 % natural wood from forests and plantations. This raw material comes in the form of trunks or branches. The
wood is then processed with high speed cutting tools in accordance with ÖNORM M 7133.
The raw material is stored and transported in completely dry conditions. The system user should also ensure completely dry storage conditions.
Optimum and effective combustion can only be ensured under these conditions.
Fuel requirements
For combustion in the PYROT, use woodchips with a maximum coarse
percentage of 20 %, a maximum cross-section of 5 cm² and a maxi-
mum length of 12 cm (5 % with max. 16 cm).
Bulk density S (kg/m³, water content W (%), size G (mm) as per ÖNORM M 7133
S 200 W20 G30/50 Soft natural woodchips from forests
S 250 W20 to W35 G30/50 Soft natural woodchips from forests
S 300 W20 to W35 G30/50 Soft/hard natural woodchips from forests
S 300 W35 to W50 G30/50 Soft natural woodchips from forests
S 350 W20 to W35 G30/50 Hard natural woodchips from forests
Quality characteristics
High quality woodchips:
■ As per ÖNORM M 7133
■ Size G30 or G50
■ Max. 5 % outliers
■ Smooth surfaces
Low quality woodchips:
■ Frayed surface
■ More than 5 % outliers
■ Coarse percentage higher than 20 %
■ Greater than G30 or G50
Principles of wood combustion
6
PYROT
1
5822 516 GB