Structure Optimization Of Vertical Iron Roller Rice Mill Based On Discrete Element EDEM

As one of the staple foods of Chinese people,rice has always been in a tight balance between supply and demand.The loss of raw materials during processing is one of the reasons for the tense relationship between rice supply and demand.Rice grain breakage is the main cause of raw material loss in the whitening stage,and reducing the breakage loss of rice grains during the whitening process is an urgent problem to be solved in the rice milling industry.In order to reduce the breakage rate of rice grains in the whitening process,this paper takes the vertical iron roller rice mill as the research object,combined with the discrete element software EDEM,conducts simulation research on the whitening process of the vertical iron roller rice mill,and combines the research The results are structurally optimized.The specific work and results of this paper are as follows:(1)Using the discrete element method to analyze the collision and fragmentation process of rice particles with different moisture contents at different falling velocities.By establishing a single grain and two grain collision contact model in EDEM,observe the corresponding grain collision results.The results indicate that within the set moisture content range,the rice particle breakage rate increases with the increase of moisture content and collision velocity.The critical crushing velocities of intact rice grains in the collision model of single and two rice grains are similar,with values of 23.5m/s and 22m/s,respectively.The speed and moisture content have a significant impact on the crushing morphology of rice grains,and when the moisture content is 10.6%,the maximum speed that the rice grains can withstand without crushing is 22m/s.At this time,the crushing rate of rice grains is small and meets the whitening requirements(2)Propose an equivalent spherical particle model to replace the rice grain model as a rice grain modeling method.Using discrete element software EDEM to design equivalent rice particle model experiments,the optimal collision speed of rice particles is obtained based on the rice particle collision contact model,and a rice particle equivalent ball particle bonding bond test scheme is designed to obtain the particle bonding bond parameters between equivalent ball particles.(3)Modeling and simulation of a MLP21 vertical iron roller rice mill was carried out,and the rotational speed of the roller,the gap between the whitening chamber and the inclination of the milling bar were used as variables,and the rice grain breakage rate under different parameters of the whitening chamber was obtained.Use the equivalent rice grain model constructed in(2)to perform the simulation.Use the "Particle Replacement API" in EDEM to replace some particles with equivalent spherical particles,and the remaining particles are filled with a simplified rice grain model without bonding bonds.The feeding mode is set to continuous feeding during simulation,and the final result is determined by the bonding bond.The number of fractures judges the rice milling and broken rice rate under different structural parameters,and compares the actual milling and broken rice rate of the MLP21 type to verify the rationality and correctness of the structure simplification of the milling room in this paper.(4)The effect of different milling room structural parameters on the milling and broken rice rate was analyzed by response surface method.Using the Design-expert response surface analysis software,the fitting quadratic polynomial equation between the broken rate of rice grains and the structural parameters of each milling chamber that affects the broken rate was obtained,and the influence of each parameter on the broken rate of rice grains was analyzed,and the optimal milling rate was obtained.Compared with the lowest broken rice rate of the test combination,the optimal result of the combination of white room structure parameters was reduced by 3.8%.The results show that when the gap between the whitening chamber is 11.5mm,the roller speed is 1050 rpm,and the milling angle is 28°,the rice grain breakage rate is the lowest at 15.0%.The research results of this thesis can provide theoretical reference for the rice grain crushing mechanism in the whitening room and the structure optimization of the vertical iron roller rice mill.