[Science] How is biomass pellet fuel made?

 

The forming technology of biomass pellet fuel refers to the process of dispersing various kinds of biomass raw materials such as straw and wood chips that are originally dispersed without a certain shape under the action of a certain temperature and pressure. After being crushed and dried, it is a new technology that presses into various shaped fuels with a certain shape and high density. 

Biomass pellets are formed into pelletized fuels, with a diameter of 6-12mm that can be processed into different specifications by changing the abrasive tool, and pellets of 4-12mm in length can be produced in different specifications through the adjustment of the cutter. Its quality is equivalent to medium-grade bituminous coal, which can be burned directly and its combustion characteristics are significantly improved. At the same time, it has the advantages of less black smoke, strong firepower, full combustion, no fly ash, clean and hygienic, and less pollutant emissions. It is easy to transport and store. It is an environmentally friendly and clean production process. It is also a comprehensive utilization of waste crop straws and wood scraps. One of the effective ways to achieve this has received extensive attention at home and abroad in recent years. 

Biomass fuel pellet making equipment is to prevent the material from rebounding back to its original shape and maintain a certain shape and strength. The compression process does not need to add any binders. It belongs to the physical molding of fiber materials. From the perspective of the composition of biomass such as straw and wood chips, it is mainly composed of cellulose, hemicellulose, lignin, resin, wax and other components. Among the various components that make up biomass, lignin is generally considered to be the best internal binder inherent in living organisms. At room temperature, the main part of the original lignin is insoluble in any organic solvents, but the lignin is amorphous and has no melting point but a softening point. When the temperature reaches about 70°C to 110°C, it softens and the adhesion starts to increase. At this time, a certain pressure is applied to the outside to make it tightly bond with cellulose, hemicellulose, etc., and at the same time to glue with neighboring biomass particles. Join together. After being cooled down, the strength of the briquettes increases, and a rod, block, and granular biomass solid briquette fuel with combustion properties similar to wood can be obtained. The entire molding process is a physical extrusion bonding molding, which does not cause any pollution to the atmosphere.