Study On The Compression Characteristics Of Biomass In Bi-taper Mode

With the development of science and technology, biomass as a renewable energy wasfound by human. Biomass is more, renewable, easy to burn and low pollution than fossil. Butbiomass volume is too big to transport, we should decrease their volume though biomassbriquetting. Biomass hydraulic briquetting machine is a kind of machine of normal temperatureopening mold in common. The mold structure is one of the important factors to biomassbriquetting. But the research on the mold is only in straight or single taper mold at home andabroad. Although the processing of straight mold is easy but the effect of briquetting is notgood and the time of keeping shape is short. Under the same outlet diameter and same material,the angle of taper is smaller, the mold is longer, and the friction was generated in compressionis bigger. It is easy to make the biomass blocked in the mold and the taper broken.1. To solve this problem, we design a kind of bi-taper mold. It is a mold with two tapersform big and small. The material passed through two taper and was extruded form mold undertwice pre-pressure. we did stress analysis to process of mold working based on the Elasticityand Plasticity theory. And research the impact of the structural dimensions of the mold fordensity, and get that there is a close relationship between the forming effect and the structure ofdouble taper die. Besides, during the extrusion process, the stress on longitudinal section istwice than it on the transverse section.2. Second, we had processed three kinds of bi-taper mold in different structuredimensions, and compression tested on various biomass materials in the laboratory of BeijingForestry University. We used pressure collector measure peak pressure of materials in threedifferent bi-taper molds. Study the law of the peak pressure during materials extrusionprocessing. 3. Last we use ANSYS to simulate the process of the biomass briquetting, and get thestress-strain law of the biomass moving in the bi-taper mold. Third, we get the max pressurelaw and the relationship between the max pressure and density in different material andstructure mold by test. ANSYS simulation result was compared with the experiment, we foundthat the ANSYS is good at simulating the internal changes in the process of compression, it iseffective for studying the law of biomass briquetting.In a word, in the field of biomass normal mode densification technology, it is feasible tomake bi-taper mold instead of single taper or straight mold. Besides, these methods andconclusions can provide reference for optimization design to normal open molding equipment.And provide theoretical basis for the development of biomass briquetting technology.