Optimization and test of roller radius of ring die straw forming machine

Abstract: Biomass briquette technology is one of the ways of biomass energy conversion. A straw briquetting machine is a main machine of straw biomass briquette. At present, the ring die straw briquetting machine efficiency is low, In order to solve the problems of low efficiency of the ring die straw forming machine when briquetting biomass, the paper makes an analysis for the rolled compaction process of the pressure roller. Research for increasing the working efficiency of a ring die straw forming machine shows that the ratio of forage again pressed into the distance and pressure roller drive torque ratio size is related to the working efficiency of a ring die straw forming machine. In the mechanical analysis of rolled compacting biomass by the pressure roller, the paper establishes its mechanical model and mathematical model., The paper first establishes a mathematic mold of working efficiency of ring die straw forming machine and the ratio of the pressure roller, setting the ratio of circular mold at 275 mm, arranges different values of the pressure roller evenly(10mm~250mm,step value: 5mm) and different friction coefficients between biomass and the pressure roller, and then calculates and maps curves of the efficiency of a ring die straw forming machine and the ratio of the pressure roller and circular's mold radius. The experiment takes corn stalk as the object of study. Effects of moisture content of biomass at home and abroad as well as the biomass particle size on machine efficiency and biomass quality have been studied a lot. Considering the grass block (dry and wet) each index power density, the maximum extrusion force, press consumption, productivity, to determine the water content is about 29%, the maximum extrusion force is small, low power consumption, suitable density, high productivity. The maximum extrusion force of die hole is f=11590N-1.and the best moisture is 29%. due to the different coefficient of the sliding friction of different particle size of corn straw and roller. With the increase of straw particle size, the sliding friction coefficient decreases gradually, ability of corn straw automatic continuous bite worse, size from 10mm to 30mm, the sliding friction coefficient varied from 0.60 to 0.46, in the grinding process of corn straw size more production efficiency is high, the selection of the particle size is 30mm.The experiment mainly chooses four coefficients of sliding friction 0.45, 0.5, 0.55, and 0.6 to analyse. die hole diameter is 32mm. With the increase of pressure roller radius, 4 different friction coefficient curves showed the same change trend, In the drawing of the image can be seen in the curve first increased with pressure roller radius, roller radius in 185mm with the increase of pressure roller radius decreasing. According to the curves, when the radius of the pressure roller is 105mm, compression distance to biomass on one stoke of the pressure roller reaches its greatest, and ring die straw forming machine has the best t working efficiency, at the same time, and obtains the optimal ratio of the pressure roller and circular's mold radius, which is 0.40, greatly improving the annular straw briquetting machine work efficiency As a ring die straw forming machine reaches its greatest efficiency, the ratio of the pressure roller and circular's mold radius is never affected by the friction coefficients between forage and the pressure roller. But the quality of formation of biomass will gradually decrease when the friction coefficient gets smaller. The optimal ratio can meet automatical biting condition: .With the grain size of 30 mm, moisture content of corn straw particles 29% as test material, different size of the roller radius for test, the biomass productivity reached the highest value ratio of 2.28 t/h roller radius and die radius was 0.40. Eventually, the paper obtained the optimal ratio of the pressure roller and circular's mold radius, which is 0.40, thus providing the basis for the selection of the pressure roller's radius.