Quality pellets – from Vapo

Producing high quality fuel pellets means getting all the variables - factors relating to raw materials, production and transportation - just right. Good pellets withstand handling and are sufficiently dry. They are clean and contain only a small amount of fines. The quality of pellets cannot be determined on the basis of their colour, however, as pellets that are very different in colour may have exactly the same properties.

Vapo’s pellet production is based on the company’s own internal quality control manual, which was prepared in conjunction with VTT Processes. It defines in detail what kind of pellets are produced at plants operated by Vapo and its sub-contractors, and how the quality is monitored.

Analysis work is continuously undertaken to ensure that the quality remains consistent. The same analyses are performed at all the plants. Certain measurements are performed every day on each shift at every plant. These monitor the moisture content of the raw material and finished pellets, the bulk density, compression strength and dimensions of the pellets, as well as the amount of fines.

Each month Vapo's laboratory in Jyväskylä analyses the moisture content, net calorific value, ash content, mechanical durability and bulk density of the pellets. Properties that are analysed every six months include ash melting behaviour, and the sulphur, nitrogen, chlorine and cadmium content of the pellets.

All stages important

The pellet production plant is an important link in the chain of processes which stretches all the way to the satisfied user. Even so, it is not sufficient to focus on production alone: raw materials and transportation are equally important factors. And the customer's pellet storage and combustion systems also play a key role.

In pellet production it is essential that the raw material is sufficiently dry and does not contain any impurities. Factors such as the type of trees, their structural and other characteristics, and even the place where they grow, can affect the properties of the wood. These variations have to be taken into account.

For customers the most important thing is of course the state of the pellets when they are delivered. This requires the right storage and transportation. For this reason Vapo has paid special attention to transportation, and to ensuring that proper training is available for drivers. A system has been developed to provide records showing when and where a given batch of pellets was produced. This makes it possible to identify the cause of any problems that might arise.

Further information