wood pellet machine working characteristics
Wood pellet machine flat die is now used by many small or middle scale pellet manufacturers since it has relatively small capacity and does not occupy too much funds or area.
During the operating of wood pellet machine for sale, we find that it has some salient characteristics (or we can say advantages) over other types of biomass pellet mills (like ring die or vertical type ones). Here let’s learn together.
- Material feeding characteristic
The first place that biomass raw material enters the flat die wood pellet machine is the feeding chamber. It plays a role of caching and feeding material, and also completes the feeding to the wedge grabbing angle of roller.
The feeding chamber of pellet mill has 2 features: one is that it has broad feeding space, which can offer sufficient area for big diameter pressing roller and loose biomass material. For example, sawdust, crushed tree branch, stalk powder or the like have high content of coarse fiber, so they are light and fluffy, not easy to be fed into the pellet machine. The broad feeding chamber can rightly offer space for raw material. At the same time, the machine can use roller in large diameters, so that the grabbing angle is enlarged, and its ability of grabbing material is improved. It is measured that the unit weight of sawdust is about 200kg/m3, and the porosity is around 75%. When making pellets, its compression ratio is about 6 or above, which puts forward higher requirement for feeding chamber.
The other is that the direct feeding method which uses the gravity is highly efficient and practical. As the feeding process utilizes gravity to let the material drop down, so no forced feeding is needed. Such kind of feeding method is superior to ring die pellet machine whose material guide plate parameter shall be changed when processing biomasses with different properties, which also limits the adaptability of ring die pellet machine to raw material.
- Flat die characteristic
Take roller rotating type (R-type) wood pellet machine for example. When it works, the flat die is fixed on the machine base, and raw biomass material is extruded from the stationary pellet die holes and then cut into pellets with relatively regular length. While in ring die pellet machine, the ring die is rotary, so that the revolving ring die often throw pellets to the machine shell, sometimes cause pellets break, and the forming rate is decreased. As a result, the stationary working method of flat die wood pellet machine is good for the improvement of pellet forming rate.
As the core working part in a pellet mill, the structure parameter of flat die determines pellets quality. For processing different biomass material, the pellet mill shall be equipped with flat die in different parameters. All factors like the area with holes, hole size, hole arrangement, etc. determine pellets performance. The smaller pellet machine compression ratio is, the larger productivity it will be, but the smaller pellet density and quality is. On the contrary, if the compression ratio is too large, there will be blockage.
From years of practice, GEMCO find that for making wood pellets with the same specifications from the same material, the flat die is much thinner than ring die. Compared with ring die, flat die pellet machine has the advantages of brief structure and compact size. It can be used both sides, so the production cost is saved for users, since the flat die is a main wearing part in pellet machine. The symmetry of flat die determines it can be used both sides.
- Roller characteristic
The features of flat die pellet machine roller are that it has low rotating speed and large diameter. Its rotation speed is even less than a half of some models of ring die pellet machine roller, while the large diameter can increase the grabbing angle of roller, which makes sure it has strong grabbing ability to raw materials, and decreases the possibility of slip. However, when in working, not the whole roller is revolving. Seen from its axial direction, both the inner and outer side of roller slide; such slide is determined by the working principle of flat die pellet mill rather than material change.
Although the existence of slide can in some extent accelerate roller abrasion, but from objective perspective, the slide can increase the extruding performance of pellet machine, which makes flat die pellet machine stand out in processing biomass raw materials that contain much coarse fiber like wood.