Drying of raw material
If the moisture content of the raw material is > 10 %, the raw material must be dried. Drying is important for the production and the quality of the biofuel product, because a moisture content of 14-15 % makes pressing difficult.
Cleaning and refining the raw material
The feedstock supplied for biofuel production may contain contaminants (iron, stone, metal, etc.), so magnetic and other separators are used to remove impurities.
After cleaning, the feedstock is refined in one or two stages, depending on its input size. The fine grind is temporarily stored in a cyclone or dust separator. The aim of the grinding/grinding is to obtain the required particle size of around 0,5-1,5 mm from the heterogeneous composition and size of the raw material supplied.
Compaction
Prior to pressing, 1 to 2 % by weight of water is added to the mixture in the form of a water spray at a temperature of approximately 70 °C. Heating ensures the release of the lignin content of the wood, contributing to a more stable bonding of the particles in the product. The pulverised raw material is fed into the machine’s powder chamber. During the pressing process, the raw material is fed to the rollers, where the rollers press the material through the so-called matrix. During the process, the raw material is pressed through the holes in the matrix, where a knife cuts or breaks it to the appropriate length.
Cooling
The prepared and still warm (~90 °C, slightly plastic) biofuel is passed through an air cooling system, slowly reaching ambient temperature. The cooling phase increases the strength of the biofuel and reduces the possibility of dust formation during further handling and handling. Countercurrent cooling results in a gradual, slow cooling of the biofuel, reducing the risk of deterioration in response to sudden temperature changes. After the cooling phase, the biofuel is spread out on a shaking table, where fine dust and rejects accumulated during the process are removed.
Packaging
The finished biofuel product is sold in 15 kg or 1 m3 bags (big-bags) or bulk (tanks) according to customer requirements.