Analysis Of Straw Crushing Characteristics And Optimization Of Crushing Equipment Structure

The crop stalk is the largest renewable resource in agricultural production,with extensive applications.The crop stalk return to the field is an important application approach.This method can increase soil organic matters,improve soil structure,and enhance the ability to conserve water and preserve soil moisture.Meanwhile,it is also an important measure to protect environment,develop ecological agriculture and achieve agricultural sustainable development.Tobacco stalk as an important category in crop stalk,they carry the pathogen,so they are not suitable for directly being crushed and returned to the field.Thus,the biomass value of tobacco stalks should be overall utilized after tobacco stalks are crushed and processed.At present,tobacco planting quantity is enormous in China,a large number of tobacco stalks need to be recovered and crushed for comprehensive treatment.However,the current theory about the crushing of straw and tobacco stalks is not mature,and all kinds of pulverizers have different levels.Hence,tobacco stalks are chosen as the object of crushing in this study.Based on the research of tissue structure and mechanical properties,optimization design was carried out for the structure of existing crushing equipment to make it applicable to hard stalk crushing.Then,working parameters of the optimized stalk crusher were optimized through the experiment to increase the pass rate of crushed particle size and reduce crushing power consumption.The related technology and equipment of tobacco stalk can also promote the formation of corn,sorghum and other straw crushing technology and equipment.Firstly,the external size of tobacco stalks was measured,and tissue structure of fresh tobacco stalks was analyzed.The microcomputer-controlled electronic universal testing machine was applied to study the mechanical properties of tobacco stalks,including tobacco stalk compression,bending and shear,etc.Mechanical property parameters of tobacco stalks were gained by the experiment to provide the reference for crusher feeding mechanism and cutter optimization.In addition,the parameters required for tobacco stalk modeling in EDEM were obtained.Secondly,for the problems of stalk crusher such as stalk blockage,sliding,large vibration amplitude and high cutting power consumption,theoretical analysis and optimization design were performed for the critical components of the crusher bycombining characteristics of tobacco stalks,including optimization design of feeding mechanism,optimization design of stalk cutting device,distribution design of hammers and stress analysis.Thirdly,FLUENT was adopted for simulation analysis of flow field in the crushing chamber to get the distribution nephogram of pressure field and velocity field in the crushing chamber at different revolving speeds.The influencing rule of rotor speed on negative pressure characteristics and airflow velocity in the crushing chamber was acquired through contrastive analysis of flow field characteristics.In accordance with tissue structure characteristics and mechanical properties of tobacco stalks,Bounded Particle Model(BPM)of tobacco stalks was established.EDEM discrete element software was used for simulation of the crushing process,and the crushing effect and blowdown effect of the crusher at different revolving speeds were investigated.The structure of crushing chamber was optimized according to the results of simulation analysis,including crushing chamber structure optimization,trapezoid toothed plate layout,and outlet screen design.After the optimized simulation result was compared with the pre-optimization result,it was found that,the material-airflow circulation phenomenon in the crushing chamber weakened obviously after the optimization so that blowdown became smoother and the crushing effect improved.Finally,single factor experiment,the combined test of quadratic regression and orthogonal rotation and response surface analysis were applied to analyze the comprehensive effects of feeding speed,rotor speed and screen diameter on the pass rate of crushed particle size.In the meantime,multi-objective optimization was carried out for working parameters of the crusher.The optimal working parameters were gained.The experiment verified that the optimization results were correct and feasible.