How Does a Biomass Pellet Plant Work?

There are a series of devices in a biomass pelletizing line, or biomass pellet plant, which are closely linked and work together to complete the pelletizing task. Then what is the working principle of the core part, the pellet mill? Let's check it out.
A ring die pellet mill is typically adopted in large-scale biomass pellet plant, while the flat die one is more commonly used in small-volume production lines. Both of them finish the pelletizing work with the interaction between the roller and the die. The principle distinction lies in the specific shapes of the die, which is also the basis for classification. We'll take ring die pellet mills as examples.

The basic structure of the pelletizing chamber of a ring die pellet mill is shown in the figure:
It is mainly composed of these parts: the die, the rollers, and the cutters. The material that has been crushed and adjusted to proper moisture in pretreatment part of the biomass pellet plant will be put into the pelletizing chamber of the ring die pellet mill first. When the machine is started, the electric motor will drive the ring die to rotate. And the rollers will also revolve on its own axis due to the friction between itself and the die. By means of gravity and the centrifugal force generated by rotating of the ring die, material will be firmly attached to inner surface of the ring die. The feeding blade will ensure the material to be continuously and evenly pushed forward along the die to be prepared for pelletizing. Then the material is squeezed by the roller and the die, and with the gradually increasing pressure, the density of the material also becomes higher. Thus the material temperature will rise, which softens the lignin in it and makes it easier to be shaped. At this time, the material is compressed into the die holes and shaped into small cylindrical strips with diameters of 6 - 10 mm (depending on the size of the holes). Finally, the cylinder will be cut into several-centimeter-long pellets, and thus is OK for subsequent steps.
That is the working principle of a ring die pellet mill in the biomass pellet plant. Have you learned the essence of it? For more questions, please visit our website and give us a phone call when convenient.