Research On Solid Straw Inoculant Spray Machine

Straw decomposing inoculants are widely used to accelerate straw decay in straw returning to soil. While applied, solid inoculant is mixed with urea by a certain proportion, and stored in the container of the spray machine attached to a tractor. It is needed to control spray rate to match the tractor’s moving speed to ensure that the inoculant is evenly spread on a field. The mixture of the two solid grains with different sizes is to be layered by continuous shaking along with the tractor’s movement, which have negative effect on the spray uniformity. In this paper, a solid inoculant spray machine is designed and made. It is studied by discrete element method simulation and on-site test to verify its effectiveness. The major work is as follows:First, the mechanical and physical properties of solid straw inoculant, urea grain, and their mixture are measured and tested to obtain needed parameters, such as bulk density, angle of repose, sliding friction angle, the sliding friction coefficient, etc.. Based on these parameters, the prototype of the spray machine is designed, and its structure and working process is described. Specifically, the stirring and feeding sub-system, the key part of the machine, effectively overcomes the mixture layering problem by use of mixture circulating loop.Second, the stirring and feeding sub-system is modeled and simulated by use of the discrete element method(DEM) analysis software EDEM. The spray rate is calculated and curved separately in relation to spiral angle of the screw blade, speed of the screw blade, discharging caliber and material surface friction coefficient.Third, The linear regression equation between discharging amount and every technical parameter is obtained, by analyzed and calculated every factors in DEM. The field experiments is carried on spray machine developed and proves that its computed result and the measured data basically tallies. Simulation results are verified the reliability after machine work performance test, and the equation can be used to adjust the process parameters. Maximum spray rate and working speed are known, according to the test of spray width and amount. This machine can meet the application requirement.A solid inoculant spray machine is designed and manufactured, based on the mechanical and physical properties tested to mixtures. Spray process is modeled and simulated by the EDEM software. The relationships,between discharging amount and every technical parameter, are set up through the method combined simulation calculation and test. The field experiments indicated that this solid straw inoculant spray machine works steady and sprays materials evenly. It can satisfy the application requirement. According to the successful development on spray machine, a new kind of high efficient operation equipment is provided to apply solid straw inoculant and it will be popularization and application more effective.