Simple Wood Pellets Quality Test

Consumers should examine the following wood pellet characteristics:

• Size: Most wood pellets produced as fuel are either 6 or 8 mm in diameter and about 3-4 times the diameter in length.
• Moisture content: The best moisture content range should be between 8-10%.
• Ash content: Good quality wood pellets have a very low ash content, below 0.7%.
• Mechanical durability: This measures how well the pellets can stand handling. Every time pellets are handled, some of them break, and all of them show some wear, which will increase the number of fines. A durability of 97.5 should be required.
• Binding agents: If the proper feedstock, such as conifer sawdust, is used, it should not be necessary to use a binding agent to make wood pellets. However, a binding agent is often used where broadleaved species are the material. The kind and amount should be declared if an agent has been used.
• Bulk density: this measures the weight of a certain volume of loose wood pellets and should be 650 kg/m3 loose volume. If the weight is too low, the pellets have not been compressed enough, which might result in increased fines.
• By using smell and visual appearance, and the simple tests outlined here, wood pellet quality can be quickly determined.
• Amount of fines: Fines hinders pellets from tumbling down to the in-feed auger, thus disturbing fuel feed to the boiler. Boilers are adjusted to burn wood pellets, but if fines arrive in the burning chamber, the flame may get too hot as fine particles burn faster than pellets. In the worst case, the ash might sinter, meaning the burner must be cleaned after it has cooled down. The number of fines should preferably be declared for each bulk delivery and is measured at the final point in the factory production chain. Fines should preferably be less than 1% by weight. Pellets are usually screened before leaving the production facility. Pellets in bags tend to have fewer fines than those delivered in bulk. Pellets stored in silos can have an increased amount of fines on delivery.

Reference Source:

http://www.coford.ie/media/coford/content/publications/projectreports/cofordconnects/ccncheckpelletquality.pdf