Study Of Biomass Briquetting Characters And Briquetting Machine Dynamic Analysis

Briquetting technology can densify unconsolidated biomass, increase the energy density, improve the combustion properties, replace coals as clean energy used in every field of production and living, and solve storage and transportation problems. It is an important technical method of integrated and large-scale use of biomass. But there are still some development bottlenecks, such as poor briquette quality, low productive capacity, high power consumption, short lifetime of key equipment components, vibration and so on. So Biomass briquetting technology study has a profound significance to establish new field of energy.In this paper, ring module briquetting technology is the research object. On the basis of analyzing biomass particles deformation law in the compression process, the main biomass bonding mechanisms agree to ring module briquetting features were gained. Based on this, the stress of compression roller, screw feeder and main shaft was analyzed theoretically, and the effect of stress variation of key components on operational stability was gained. Combining with rolling forming mechanism, the optimization scheme was proposed.In order to gain the biomass ring module briquetting mechanism, a series of experiments were conducted to study the effect of biomass types, biomass water content, briquette machine structure and operation parameters on briquette relax density, power consumption, productive capacity and forming rate. The results showed that increase with water content, the relax density, power consumption and forming rate of corn stalks, cotton stalks and rice straw were all decrease, but the productive capacity showed the opposite trend. Considering these indictors comprehensively, the optimal water content is between20-25%. Residence time that determines the briquette density, forming rate and productive capacity was influenced by compression roller speed and the clearance between roller and module. Through range analysis of experimental data, the optimal roller speed and clearance is200r/min and2.5mm respectively. All these provide data for improvement of briquetting technology and rolling forming mechanism.Dynamics behavior of spindle system not only affects the life of some components, but also the briquette quality. Dynamic equation and analysis mass matrix of spindle system were established firstly, based on FEM theory, vibration response of spindle was simulated and natural frequency and the mode of spindle system was analyzed deeply. Through optimizing the structure of spindle system, the roller displacement was decrease and rigidity and vibration resistance of spindle system were improved. The variation of maximum response stress and displacement with frequency was gained, the maximum displacement and response stress of the installation site of roller was0.696mm and140MPa respectively, which was far less than the spindle allowable stress of600MPa. Through optimization, the maximum spindle stress and displacement under operation frequency were all decrease.Based on S-N curve of spindle and fatigue damage accumulation principle, the fatigue life model of spindle was established with the nominal stress method, and fatigue life of spindle was analyzed. The results showed that the minimum life was8.4×105and the safety factor was0.99, which didn’t satisfied with spindle fatigue strength requirements. Through optimization, the minimum safety factor was increased to2.3, and the fatigue sensitivity decreased.