The composition and manufacture of wood pellets

Otherwise known as pellets, wood pellets are fuels used to heat a home. They are manufactured using a specific technique in order to have solid blocks ready for use. Several steps are therefore required to create wood pellets.

The pellet manufacturing process

The production of granulate follows a standard and automated scheme. After the wood is collected, it is crushed in a sawdust silo. Then, it is necessary to dry crushed logs using a biomass boiler or a wood pellet machine. For this purpose, it is also possible to combine it with a cogeneration plant in order to produce energy. The next steps are cyclonic separator, fine screening, granulate production, cooling, screening, storage and final dust removal. Once the manufacturing steps have been completed, the bulk loading of the pellets into trucks should be carried out. Non-compliant fine particles may be added to the mixture as raw materials.

Standards to be respected

In order to guarantee optimal combustion, wood pellets must comply with certain standards. These standards concern the manufacturing process of granules. This is the European standard for wood heating EN 14961-2. These standardizations concern both the quantity and quality of the granules. For example, care must be taken to ensure that the ash content is not too high to avoid fuel waste. A large mass of ash can also damage the heater. In addition to the ash content, the fines content, fuel hardness and moisture content must also be checked.

The certifications

In addition to these standards, there are the certifications, namely DIN and ENplus A1. These certifications also focus on the conformity of the manufacturing process and the characteristics of the granules produced. The quality of the pellets must be below the European standard. Each manufacturing plant is free to choose the standards for which it wishes to obtain certification. All certifications require the same requirement on the characteristics of the granules. The difference lies mainly in the control entity and the way the certification is communicated. The NF standard, for example, classifies pellets into three categories, namely high-performance wood, standard wood and industrial-grade wood. The latter is only dedicated to a particular use.

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