Design And Test Of The Key Components Of Ratooning Rice Topdressing Machine With Wind Conveying And Concentrated Discharge

To meet the demands of topdressing for ratooning rice,a ratooning rice pneumatic multi-row topdressing machine which adopted the pneumatic conveying method for fixed-point fertilization was designed a ratooning rice pneumatic multi-row topdressing machine which adopted the pneumatic conveying method for fixed-point fertilization.In the research process,the multi-row fertilization method was employed to increase the fertilization width,hence promoting the fertilization efficiency and fertilizer utilization rate.According to the various material characteristics of the selected urea required for top dressing of ratooning rice and the theoretical research on pneumatic conveying,the various working parts of the fertilizer applicator were designed,and the operation performance of the fertilization equipment was tested and optimized by computer simulation analysis and actual experiments to determine the relevant parameters of the key working parts of the topdressing machine and test its various fertilization performance indicators.Here are the major research contents and conclusions.(1)The material properties of solid fertilizer particles were measured.The subsequent fertilizer supply system and the design of the air-feeding collection and discharge fertilization device need to be based on the material characteristics of the fertilizer,so the urea produced by Candace Chemical(Hubei)Co.Ltd.With a total nutrient content of 46.4%or more was used as the research object,and the urea fertilizer related to the later design requirements determination of physical properties.The measured bulk density of urea was 0.896 kg/m L,and the particle density 1.403 kg/m L;the triaxial size of urea fertilizer particles was mainly distributed within 1mm～2 mm,the sphericity was 0.93,and the equivalent diameter 1.5 mm;the water content of the selected urea was 0.87%,the natural angle of repose was 34.7°,and the sliding angle of the urea fertilizer on the steel plate and the sliding angle on the smooth PVC plastic plate were23.9°and 20.9°,respectively.(2)The structure design of the key components of the regenerating rice gas conveying collecting,discharging and top dressing machine.In response to the problems of low efficiency of fertilizing machine fertilization and low fertilizer utilization efficiency in the current topdressing operation of ratooning rice,an overall structure scheme of the air-carrying collecting,discharging and top dressing machine for ratooning rice was proposed,and the structure of the pneumatic collecting,discharging and dressing fertilizer system,fertilizer supply system and chassis were designed and selected.The fertilizer separation device adopted an inverted vertical fertilizer separation method,with 8 outlet pipes,a circular truncated shell structure,and a conical disperser and a guide vane to divide the gas and fertilizer mixed flow.The cone angle was 90°;the gas and fertilizer mixing the device adopted a bilateral symmetrical fertilizer feeding method,which mixed gas and fertilizer in the vertical direction.The longitudinal pipe structure was designed according to the principle of venturi.Straight pipe,the designed air supply device mainly included the air inlet pipe and the air plenum;the Y-type air flow splitting device outlet angle adopted a 60°symmetrical structure.The selection of the fan for the device was decided by theoretical calculations,including the calculation of air volume and pressure loss.The calculations indicated that the required air volume of the fan was 220 m~3/h,and the air pressure of the fan should be greater than21626.7 N/m~2.The two-sided cross-type straight through type outer sheave fertilizing appliance was selected.The diameter of the sheave is 60 mm with 10 grooves,and the working length was fixed at 30 mm;the outer size of the fertilizer tank was1200mm×240mm×200 mm,and the fertilizer tank was an asymmetric structure.The internal slope angle was 35°,and there were a total of 4 fertilizer outlets;choose to adjust the speed of the fertilizer shaft through the motor speed controller and the DC permanent magnet motor to realize the adjustable fertilizer volume of the fertilizer supply system.The chassis was modified,loaded with the load-bearing,installation parts and fertilization control workbench of the fertilization device,and the chassis was widened to enhance the stability of the chassis.(3)CFD numerical simulation test was carried out on the air flow field inside the pneumatic multi-row topdressing device.In order to check and selected the appearance shape and parameters of related parts that affect the consistency of fertilizer collection and discharge of the pneumatic fertilizer collection and discharge system,the FLUENT software was used to conduct a step-by-step simulation test on the air flow field inside the pneumatic fertilizer collection and discharge device.The conclusion was reached based on the single factor test results:The layout of the side fertilizer inlets had a certain effect on the airflow velocity distribution in the vertical pipe.In terms of improving the uniformity of the airflow field velocity distribution,the bilateral symmetrical layout of the side fertilizer inlets had better performance than the unilateral arrangement.The results of the two-factor test showed:The combined action of the air supply device with the air pressure chamber and Bellows could improve the consistency of air flow splitting velocity distribution in the pneumatic fertilizer collecting and discharging device.(4)The performance of the working parts of the designed ratooning rice pneumatic collection and topdressing machine was tested to determine the working indicators of the fertilizer discharging device.The performance of the external tank wheel fertilizer discharging device in the fertilizer supply system was tested.The results showed that the fertilizer supply system satisfies the fertilizer application range of 87kg/hm2-365 kg/hm2,including the range of ratooning rice fertilization requirements,the stability of the fertiliser and the discharge of fertilizer.The uniform performance also met the top dressing requirements of ratooning rice.Based on the preliminary structure design and CFD numerical simulation test results,the bench fertilization test was carried out to verify the rationality of the overall structure design and theoretical analysis of the pneumatic fertilization device,and the optimal air supply device with an air plenum and vertical bellows were determined combination.Carry out a bench test study on the influencing factors of the uniformity of fertilizer,taking the angle of fertilizer,the height of fertilizer,the length of the bellows,and the speed of the fertilizer shaft as factors,a single-group pneumatic fertilizer collecting and discharging device was used to carry out a quadratic regression orthogonal rotation combination Experiment,study the factors affecting the uniformity of fertilizer distribution and their influence rules,establish a regression equation to optimize the parameters of each influencing factor,and obtain the best combination of parameters:fertilizer inlet angle 54°,fertilizer inlet height 216 mm,and bellows length 200 mm,The speed of the fertilizer shaft was 47 r/min.Fertilization performance test of the whole machine,the test showed that the fertilization indexes of the regenerating rice air-feeding collecting and discharging topdressing machine meet the national fertilization standards.