Wood pellet quality experiment analyze on crack forming
The result of wood pellet cracks forming experiment shows that water content has a major influence, that would lead to the moisture controlling of raw material, also there’re other factors that should not be neglected.
Raw material type: the molding effect of pure sawdust is the best, then the cotton stalk and corn straw. Different from the sawdust from wood processing factory, it is for the lignin and fiber micro-structures of these 2 materials, after the press process, the residual stresses of the pellets are so different that the molding effects are not the same level.
Particle crushing: raw materials should be crushed into even particles, larger particles are not good for pellet making, the perfect particle size of the pure sawdust is 3mm, cotton stalk-5mm, corn straw-10mm.
Molding pressure: with the same molding pressure adopted-10MPa, pellet made of pure sawdust has the best molding effect, corn straw and cotton stalk are secondary. If you’re using other raw materials, make some test before the production.
Temperature factor: when the temperature maintains at a high level for a long time, deep carbonization would happen and the pellets would become fragile. Some study shows that proper temperature could help soften the lignin matter and speed up the release of residual stress within the pellet.