The Study And Manufacture Of Biomass Briquetting Machine Based On ANSYS

The Biomass Miss-energy has received wide attention in the situation of the shortage of traditional energy. Our country has the rich crop stalks resources, and the annual output is 600,000,000 tons, but the combustion mode and utilization approach are very single and out-dated, the utilization is very ignoble. Most of them are burned out which brings serious resource waste and environment pollution. So the research on the biomass miss-energy conversion technology causes widely attention. Among them , the composite curing processing technology can make the loose crop stalks into compact fuel which can instead of the coal. This has the important significance in improving the rural life quality, protecting the agricultural ecological environment, increasing the farmers'income and promoting the agricultural sustainable development.The paper researches on the influencing factors of the biomass forming process, according to the analysis of the biomass forming technology to know the influences of temperature and rheological law for the forming quality. With the help of the finite element analysis theory and the extrusion process analysis using ANSYS, combining the simulation conditions to research the influencing factors for production quality and process parameters, and on these basis, after comparing the advantages and disadvantages of the forming machine, at last designs and manufactures a new type biomass forming equipment. The paper also does the experimental study on the new type equipment.The major research contents are as follows:1. Determine the research method. The paper introduces the basic ideas and steps of FEM and its function of ANSYS. Uses the structural analysis module of ANSYS to analyze the contact and thermodynamics theory basis, then builds and simulates the finite element model.Building the finite element mechanical model is the key to the structural analysis of the subject. According to the main features of the biomass composite curing processing and the relative forming theory of powder technology, uses the Drucker-Prager Criterion to derive the elastic-plastic constitutive equation. During the build process of the mechanical model, uses the 2 d axisymmetric model. The mould material Elastic Modulus is 210GPa, the Poisson's Ratio. The corn stalk's density is 400kg/m3, its cohesion is 20.32kPa and internal friction angle is 10.14 . The friction coefficient is 0.4. The mapped mesh generation method is used in the process of the model building. The generated grid units'shapes are uniform, and the calculation is easy to convergence. The contact elements use plane-plane contact units, for the plane-plane contact form supports the large deformation with large sliding and friction, and has higher calculation accuracy. This paper uses the contact wizard to build the contact pair. During the solving setting process, the paper mainly considers some properties of nonlinear analysis, opens linear search function, and uses the Full N-R unsymm equation solver when calculation.The simulation result reveals the rheology character during the biomass extrusion process, the extrusion deformation shows as Fig.1. From the mesh morphing conditions, we can see the mesh changes strenuously at the outlet and presents as Diamond-Shape, which shows that there has shear stress in the material and the shear stress is produced by the interactions of extrusion force and friction of material. And it is the key reason of cracks which will appear after the material out from the mould.According to the simulation of material's temperature field using the THERMAL module of the ANSYS, the paper uses the enthalpy method to solve the changes of heat transfer performance caused by the temperature, and obtained the change law of the temperature field in the compact forming process. Contrasts the temperature fields of three temperatures, analyses the change of the material. The result shows that the heating temperature changes faster under the temperature of 250℃, and the straw is easier to softening. Comparatively speaking, the heating temperature changes slower under the temperature of 150℃, and it needs long time to soften the straw.2. According to the requirement of the actual production of the straw forming, the paper proposes some design parameters and determines the mechanical part's general layout and the hydraulic system's working principle of the compact forming machine.The structure of the biomass forming machine which researches in this paper mainly composed by the frame, intake mechanism, cut-off device, forming device, heating device, double cylinders system, hydraulic system, electric control system and kinetic transmission system. The technical schemes are as follows: on the basis the current double cylinders system, forming device hydraulic system and electric control system, fixes the feeding device composed by double rollers respectively used to extruding, rolling and structure failure, volume compacting on the frame, and the discharging port connects with the extrusion cylinder's material entrance of the forming device with is fixed on the frame; fixes the double extrusion heads which respectively fixed with cutter blade and density regulation head on the piston-rod end of the double cylinders; fixes sets of far infrared ray heater which are used to heat the biomass straw on the outside of the two taper tubes.The equipment has many advantages: it can make the shaped without been crushed and dried; the equipment which used to be composed by several sets is simplified to be composed only by one set; the process which used to be material crushing-drying- feeding-forming is simplified as feeding-forming; the application of far infrared ray technology broadens the demand of the straw's moisture content. The equipment can solve the problem of restricting the development of biomass forming technology.3. According to the experimental test on the self-made biomass forming equipment, analyses the affection of the pressure, temperature and moisture content changes to the compact density and relaxed density of the compact block. Seeing from the single factor test data, the relation of the straw's moisture content and the relaxed density presents as the parabola-shape, the compact density is biggest and relaxed density is smallest when the moisture content is about 18%, and has the excellent molding effect. With the increasing of the compact pressure, the compact block's compact density increases and the relax ratio decreases. The compact density is biggest while the relax ratio is smallest. When the temperature changes within 150℃-250℃, the compact block has the better forming quality, and the relax ratio changes little. Too high or too low temperature all will affect the compact density and relax ratio. It is different to form when the heating temperature is 100℃, the compact block is dust color and presents black color when 300℃.The coming out of the straw forming machine is the deep development and usage of the agricultural resources. According the transmission of the straw forming machine, we can efficiency use the biomass energy, produce the clean fuel, which can instead the coal, petroleum, natural gas, etc. It also can extend the agricultural industry chain. Besides, biomass forming is a new industry which can change the waste such as agricultural byproducts, remainder and wastes into valuables.