| With Biochar has become a new type of soil conditioner as the problem of land pollution continues to be serious,and biochar can be returned to the field to achieve soil remediation and effective soil improvement.In order to achieve uniform mixing of biochar and soil and improve the utilization rate of biochar,this paper designs a device for uniform mixing of biochar and soil,and optimizes the parameters of the device,the main contents and conclusions are as follows:(1)Calibrating discrete meta-simulation parameters of biochar particles.To obtain the discrete element simulation parameters of straw biochar,a combination of simulation analysis and physical tests was used to calibrate the biochar contact parameters.The Placket-Burman test was used to screen the parameters significantly affecting the biochar dispersion element,the steepest climb test to determine the optimal range of significant parameters,and the Box-Behnken test to determine the three significantly affecting parameters as charcoal-charcoal rolling friction coefficient 0.097,surface energy JKR 0.018 J/m~2,and charcoal-steel rolling friction coefficient 0.256.A stacking angle The comparison between the experimental and Rocky discrete element simulation results shows that the error of the determined parameters is 2.33%,which satisfies the parameter setting requirements for simulation analysis.It can be seen that the contact parameters of the biochar particles obtained from the experimental calibration can be used as a reference for the kinetic simulation study of char particles after biochar return to the field and the study of the physical property changes of the three phases of the soil(2)Design of biochar-soil mixing device.Design the size and shape of the paddle plate column and paddle plate of the mixing paddle to determine the size.In order to achieve the best mixing and stirring effect,the suitable angle between the paddle plate and the paddle plate column is designed as,through the force analysis of the mixing paddle plate,the value range of the angle between the paddle plate and the paddle plate column is determined as 30°≤≤90°;the paddle plate structure and its arrangement are designed in the paddle plate arrangement area.(3)Determination and simulation analysis of key parameters of biochar-soil mixing components.The discrete element method was used to optimize the key parameters of the biochar mixing device,and single-factor and multi-factor tests were conducted respectively.The single-factor simulation test was conducted with the angle between the paddle plate and the paddle plate column,the number of paddle plate columns on the mixing paddle plate,and the rotational speed as the factors and the coefficient of variation of biochar particles in different soil layers as the indicators,and the two-factor five-level rotation combination test was conducted for the rotational speed and pitch angle,and the final determination of the paddle plate arrangement The optimal parameters were set as five paddles in the length L of the area,the angle between the paddles and the paddle column was 55.86°,and the rotational speed was 201.2r/min.Discrete element simulation tests were conducted to analyze the mixing process under the optimal parameters.(4)Experimental analysis of the biochar-soil mixing device.According to the optimal parameters obtained from the simulation test,the mixing paddle was processed and the test bench was built for the test,and the single-factor test was conducted with the mixing paddle rotational speed and forward speed as indicators and the coefficient of variation of biochar particles as indicators;and the rotational combination test was conducted for the mixing paddle rotational speed and forward speed to optimize the working parameters,and the optimized working parameters were obtained,and the rotational speed was taken as 190r/min and the forward speed was taken as the actual situation The coefficient of variation of biochar particles of0-5cm,5-10cm and 10-15cm was 15.53%,15.95%and 16.62%respectively. |
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