Using loose biomass to produce pellet fuel at room temperature is a simple and direct way to utilize biomass energy. Let’s discuss the mechanical forming technology of crop straw pellets with you.

After the biomass material with loose structure and low density is subjected to external force, the raw material will undergo the stages of rearrangement, mechanical deformation, elastic deformation and plastic deformation. The inelastic or viscoelastic cellulose molecules are intertwined and twisted, The volume of the material is reduced and the density is increased.

The compression ratio of the ring die of biomass pellet machinery equipment determines the size of the molding pressure. The cellulose content of raw materials such as corn stalks and reeds is small, and it is easy to deform when extruded by external forces, so the compression ratio of the ring die required for molding is small. , that is, the molding pressure is small. The cellulose content of sawdust is high, and the compression ratio of the ring die required for molding is large, that is, the molding pressure is large. Therefore, different biomass raw materials are used to produce molded pellet fuel, and different ring die compression should be used. For biomass materials with similar cellulose content in the raw materials, ring die with the same compression ratio can be used. For the above-mentioned raw materials, as the compression ratio of the ring die increases, the particle density increases, the energy consumption increases, and the output increases. When When a certain compression ratio is reached, the density of the formed particles increases slightly, the energy consumption increases accordingly, but the output decreases. A ring die with a compression ratio of 4.5 is used. With sawdust as the raw material and a ring die with a compression ratio of 5.0, the density of the pellet fuel can meet the quality requirements, and the energy consumption of the equipment system is low.

The same raw material is formed in ring die with different compression ratios, the density of pellet fuel increases gradually with the increase of compression ratio, and within a certain range of compression ratio, the density remains relatively stable, when the compression ratio increases to a certain extent, The raw material will not be able to be formed due to the excessive pressure. The grain size of the rice husk is large and the ash content is large, so it is difficult for the rice husk to form particles. For the same material, in order to obtain a larger particle density, it should be designed using Larger ring mode compression ratio.
Influence of raw material particle size on molding conditions

The particle size of biomass raw materials has a great influence on the molding conditions. With the increase of the particle size of corn stalk and reed raw materials, the density of the molding particles gradually decreases. If the particle size of the raw material is too small, it will also affect the particle density. Therefore, when using biomass such as corn stalks and reeds as raw materials for particle fuel production, it is more appropriate to keep the particle size at 1-5 nun.

Influence of moisture in feedstock on density of pellet fuel

There are an appropriate amount of bound water and free water in the biological body, which have the function of lubricant, which reduces the internal friction between the particles and enhances the fluidity, thereby promoting the sliding and fitting of the particles under the action of pressure. When the water content of biomass raw materials When the moisture content is too low, the particles cannot be fully extended, and the surrounding particles are not tightly combined, so they cannot be formed. When the moisture content is too high, although the particles can be fully extended in the direction perpendicular to the maximum principal stress, and the particles can mesh with each other, but Since more water in the raw material is extruded and distributed between the particle layers, the particle layers cannot be closely attached, so it cannot be formed.

Therefore, when biomass pellet machinery and equipment use biomass such as corn stalks and reeds as raw materials for the production of pellet fuel, the moisture content of the raw materials should be kept at 12%-18%.

Under normal temperature conditions, during the compression molding process of biomass raw materials, the particles are deformed and combined in the form of mutual meshing, and the particle layers are combined in the form of mutual bonding. The content of cellulose in the raw material determines the difficulty of molding The higher the cellulose content, the easier the molding. The particle size and moisture content of the raw materials have a significant impact on the molding conditions.