Design And Experimental Study Of Biochar-Based Fertilizer Mixing Device

China’s agriculture is facing a double challenge of rising fertilizer costs and declining efficiency,which not only threatens food security,but also aggravates environmental pollution.Carbon-based fertilizer is a new type of soil amendment and fertilizer,which has the advantages of improving soil properties,increasing soil microbial activity,increasing crop yield and quality,reducing greenhouse gas emissions,etc.The mixed application of carbon-based fertilizer and traditional fertilizer can reduce nutrient loss,prolong fertilizer efficiency time,reduce fertilizer dosage,effectively improve fertilizer utilization rate and effect.This paper designs and develops a set of carbon-based fertilizer mixed fertilization device and its control system,which can realize the functions of mixed fertilization,variable fertilization,data upload,remote monitoring,etc.This paper uses theoretical analysis,discrete element simulation analysis,experimental research and other methods to study the physical properties of carbon-based fertilizer,mixed fertilization control system,key components of mixed fertilization device,and obtains a series of conclusions and data,which verify the rationality and superiority of the design and performance of the mixed fertilization device.This paper provides a new technical scheme for the mixed application of carbon-based fertilizer and traditional fertilizer,which has certain innovation and practical value.(1)This paper compares and analyzes the physical properties of two kinds of carbonbased fertilizer granules and one kind of compound fertilizer granule.The results show that the equivalent diameters of both carbon-based fertilizers are slightly larger than that of compound fertilizer;the sphericity is slightly smaller than that of compound fertilizer;the moisture content is larger than that of compound fertilizer;the single particle density is smaller than that of compound fertilizer;the bulk density of compound fertilizer is between that of two kinds of carbon-based fertilizers.In addition,there are significant differences in static friction coefficient and restitution coefficient between fertilizers and different materials.The collision restitution coefficient between fertilizer granules and plastic is the largest,followed by that between fertilizer granules and steel grade 45,while that between fertilizer granules is the smallest.It provides reasonable data for the analysis of fertilizer discharge performance by discrete element method.(2)Explore the influence of working parameters of outer groove wheel on the fertilizing performance of three kinds of granular fertilizers.The results show that the variation coefficient of fertilizing stability decreases with the increase of rotation speed,all below 7%,indicating that the outer groove wheel fertilizer applicator can effectively adapt to the fertilizing requirements of compound fertilizer and carbon-based granular fertilizer.Combining Box-Behnken response surface experiment to explore the influence of rotation speed,effective working length and fertilizing tongue opening on fertilizing rate,the results show that with the increase of these three factors,fertilizing rate increases.The contribution order is effective working length > fertilizing tongue opening > fertilizing shaft rotation speed.And a second-order regression equation between three significant parameters and fertilizing rate is established.And the motion of fertilizer granules in the applicator is analyzed.(3)Design a spiral applicator for biochar powder,determine the optimal parameter combination by formula calculation and simulation,and achieve a minimum variation coefficient value of 17%.In order to solve the problem of difficult calculation of biochar powder particles in simulation,discrete element simulation parameters are calibrated based on particle scaling theory and repose angle.The performance test of spiral applicator was carried out by bench test,and a linear relationship between rotation speed and application rate was obtained.(4)Design a control system for a fertilizer mixer.Use OneNET cloud platform to receive and store data,and develop a micro-application for data monitoring of the mixer.Realize the functions of travel speed collection and upload,variable mixing and application,and cell phone remote monitoring.(5)The design,parameter optimization and performance testing of the fertilizer mixing and application system.The effect of fertilizer mixer angle on fertilizer granule drop speed and discharge uniformity was analyzed using EDEM.The function and stability of the control system were tested,< 7% in speed collection,with a maximum error of 6.8% in fertilizer discharge volume,and < 21% in total fertilizer discharge stability.The feasibility and stability of the fertilizer blending system were verified,and technical support was provided for variable fertilizer blending.