The straw and other materials contain certain cellulose and lignin, and the lignin is a structural monomer in the material, and is a phenylpropane type polymer compound. It has the function of enhancing cell wall and binding cellulose. Lignin is amorphous, and its main part is insoluble in any solvent at room temperature, has no melting point, but has a softening point. When the temperature reaches a certain value, the lignin softening adhesion increases, and under certain action, the cellulose molecular group is dislocated, deformed and extended, and the adjacent adjacent biomass particles are mutually engaged, recombined and pressed.
The biomass pelletmill is used to compress and extrude straw, wood chips, rice hulls, etc. in a high temperature and high pressure environment by mechanical force (squeezing force, friction, etc.), during which lignin or fiber is fully utilized. The high temperature bonding of the pigment finally compresses the biomass powder to form a pellet material.
Biomass ring die pelletmill molding technology is an advanced pelleting molding process technology that integrates multidisciplinary knowledge such as mechanical engineering and powder mechanics. In the process of pressing the biomass particles, the material is substantially deformed by the combined action of the pressing force, the friction force and the high temperature and high pressure.
According to the state of the powder in the pelleting molding process, the whole process can be divided into three zones: the feeding zone, the deformation pressing zone and the extrusion forming zone.