(202f) Numerical Analysis of Densification under Cold Compression Molding Condition for Biomass Pellet Based on Workbench

In this paper, we studied the process characteristics of densification under the cold compression molding for biomass pellet, and the inherent influence of die stress on the quality of briquette fuel. According to the characteristics of different stages in the molding process, combined with the theory of elastic-plasticity, friction law and contact mechanics, the SOLIDWORKS software was used to build the three-dimensional model of piston die, the ANSYS Workbench software was used to simulate the compression molding process. The stress and strain rules of the molding process were revealed by using the large deformation and nonlinear finite element method, and the design of the die structure was optimized. The results showed that the workbench can be used to simulate the creep process of biomass pellet in different stages of loosening, transition, compaction and moving well. The equivalent stress distribution in the molding process can be obviously changed by adjusting the cone angle, the ratio of length to diameter, material and other factors, thus affecting the quality of briquette fuel. The briquetting pressure was concentrated in the conical surface, when the cone angle of die was 60°, the compressive stress made the briquette pellet density higher, but the larger shear stress also lead to the internal rupture. The cone angle decreased to 45°, which can effectively suppressed the internal rupture and improved the quality of briquette fuel. When the aspect ratio of the die was 7.5, the flow friction effect of the biomass pellet was obvious, the maximum compression density decreased. Then the aspect ratio decreased to 6.43, the larger compressive stress was applied to the biomass pellet, which can better take into account the relationship between density and specific energy consumption, and the comprehensive molding effect was better.