Research Of Biomass Shaping With Open Mold In Natural Temperature

The technology of biomass shaping with open mold in natural temperature is one kind of biomass shaping technologies. Compared with heat shaping and shaping with closed mold at room temperature, the craft of shaping with open mold is more simple and production processes are more energy-efficient. So experimental study on shaping way was carried out to find some suitable process parameters.The thesis is based on forestry nonprofit industry-specific "woody shrub resources to promote the industrialization of sandy wasteland restoration technology " and on the basis of the results of "948 " introduction project, "High density biomass. briquette shaping technology introduction ". The experiments on a variety of biomass materials for compression shaping and stress relaxation were carried out in self-developed test-bench, and the test data were analyzed by Exce12007 and SPSS18;The shape crack of the block and microstructure image of end-face have been studied respectively with an ordinary digital camera and the German-based Leica S8 APO stereo microscope. The calorific value of the molding blocks were tested with ZDWH-8 automatic high precision computer calorimeter. Test results are as follows:1.The results indicate that density and shaping pressure of block is first from small to big, and then to small, accompanying with the increase of moisture content in the same taper; Under a certain moisture content, the density decreases with taper increasing; When moisture content get to a certain value, the lawngrass cannot be formed,First come that when moisture content is at 8% to 17% with the mold taper is at 15°to 25°,the density of turfgrass is larger than 0.9 g/cm~3.when moisture content is at 11% and mold taper is at 25°,the density of block reaches max-1.10 g/cm~3; When raw material moisture content is at 20% or above, the density of lawn grass is smaller than 0.9 g/cm~3 and shaping effect is bad or the lawngrass cannot be formed.2.If the ratio of the amount of particles of different sizes is suitable,small particles will fill the spaces between the larger particles, and shaping density reaches its maximum, so shaping effect is the best; it draws the conclusion: the particle size of forest biomass is 5mm-20mm, when mold taper is at 40°and outlet diameter is 50mm,the density reach the maximum.3.With the same mold, shaping pressure and shaping density of corn stalks are the largest, shaping pressure and shaping density of turfgrass is the least,and shaping pressure and shaping density of forest-based raw materials is between the lest and the largest.4.In the process of biomass shaping with open mold at room temperature, the model of stress relaxation is one【M】model paralleling one【H】model, the constitutive equation of stress relaxation isσ(t)=Ae-t/T+σe.5.Biomass feedstock is closer to the parietal, and the frictional resistance is larger, biomass feedstock is closer to the axis, and the frictional resistance is smaller,the material near the axis move faster than the outer materials; from the central axis to the surface, the density of biomass feedstock increases, two end faces of biomass block are concave face and convex face respectively. In microscopic image, the gap of the core particles is large than the edge particles.The microstructure of briquette end-face shows that the mechanism of room-temperature opening-mold shaping is making biomass particles extrusion deformation and fiber entanglement with each other, nested within each other is not loose.6.Calorific value of forest biomass is the largest, reaching 4,000 to 4,500 cal/g; the calorific value of crop stalks (corn stalks) is the second, to 3866 cal/g; and the calorific value of Grass material (lawn grass) was the lowest-3802 cal/g.