pellet mill: Process of wood pellet production line

Wood pellet production line is also known as wood pellet plant or pellet plant which serves for making the agro-forestry wastes into solid fuel or wood pellets. It includes crushing, drying, pelletizing, cooling, and packaging machinery. The wood pellets production process is slightly different according to different raw materials.

1. Raw material pulverizing. For tree branches and the like, the first step is raw material chipping and pulverizing (or crushing), since the suitable raw material size for pellet production is about 3-5 mm. For raw material that smaller than 5 mm like sawdust, the chipping or pulverizing is not needed.

2. Raw material drying and cleaning. Some of the raw materials contain too much moisture, which will affect the pelleting. Therefore, the extra moisture needs to be dried out. Also, the raw material may have some impurities like metal scraps or stone. These impurities must be screened.

3. Pelletizing. This is the most important part in wood pellets production process. Feed the raw material into the pellet machine hopper, then the raw material is pressed by rotating roller to go through the pellet machine die (or for one kind of flat die pellet machine, the roller is fixed, and the die rotates). Since the die is with many holes, after going through the die, cylindrical pellets are shaped. After that, the pellets are cut by a slicer near the discharge hole to keep the same length.

4. Pellets cooling. The pellets just get out from the pellet machine are very hot, their temperature can even reach 90-100 degrees Celsius, which are not able to be packed directly atall. Therefore, we need a cooler to lower their temperature. But anyway, for small productivity, cooler is not necessary, since only air cooling is enough.

5. Packing. When the pellets are cooled to room temperature, they can be packed for sale or for use directly.