Study On Online Fertilizer Mixer Of Variable Rate Fertilizer Applicator

An accurate variable-rate mixed-fertilizer applicator applies fertilizers in three fertilizer tanks according to the fertilizer requirements of a particular piece of field. Fertilizer is blended in a mixer before it is applied, which ensures accurate application. An accurate variable-rate mixed-fertilizer applicator mainly comprises an electronic controlling system, a measure of volume of applied fertilizer, and a continuous mixer.A continuous mixer, representing a device that continuously blends fertilizer on real time basis, is an essential part of a variable-rate fertilizer applicator. Up to date, a number of research institutes and universities have been developing variable-rate fertilizer applicators. While most of the researches are focused on the design and development of variable-rate fertilizer controllers, fewer efforts are devoted to the study of continuous mixers. Most of the mixers currently in use are manufactured as stand-alone products, not suitable to be installed into variable-rate fertilizer applicators due to, among other things, their large size and time-consuming quality. In light of the aforesaid shortcomings, an improved smaller continuous mixer compatible with variable-rate fertilizer applicators was designed and examined in this thesis with following approaches:1. Based on the analysis of the advantages and disadvantages of various existing types of mixing machineries, a new type of vertical mixer combining spray plates and collectors was designed. The core components of the mixer are spray plates and collectors arranged alternately. The spray plates are put around a rotating rod driven by sleeve motor. The upper end of the rotation rod stretches out of the outer case of the mixer and connects to an electric motor whose rotating speed is continuously variable subject to a limit of 900r/min. A collector is in the shape of an inverted pyramid, with its upper end fixed to the outer case of the mixer.2. Based on the simulation analysis, the structure parameters of the mixer were optimized. The complete design of the mixer was built with PRO/E, and a simplified model was then tested through simulation with EDEM, where groups of mechanical parameters of the key components were tested and an optimal design was determined. After the EDEM simulation test and subsequently an analysis of the operation process of the mixer, a force and motion analysis of the fertilizer was carried out, which helped clarify trajectory and velocity of the fertilizer particles within the mixer. Then the mixing mechanism was investigated.3. The performance of designed mixer was examed through experiments. A prototype continuous mixer designed in the above step was put through performance tests. It was found in a univariate test that (i) if the processing volume and the mixing ratio keeps constant, the evenness of the mixture rises as the rotational speed of the spray plate increases; (ii) if the rotational speed and the mixing ratio keep constant, the evenness of the mixture will rises firstly and then drops as the aggregate volume of applied fertilizer increases; and (iii) if the rotational speed and the aggregate volume of applied fertilizer keep constant, the evenness of the mixture will dropps as the difference between the volume of each fertilizer increases. On the other hand, it was found in an orthogonal experiment that the rotational speed is the paramount factor affecting the evenness of the mixed fertilizer. In other words, a higher rotational speed appeared to be a most remarkable way to offset the effects resulted from a lower aggregate volume of applied fertilizer and mixing ratio. Where the pouring speed of the aggregate volume of applied fertilizer are set to be lOg/s,20g/s,40g/s,60g/s and 90g/s, and the resulting rotational speed reaches 700r/min,700r/min,600r/min,800r/min and 900r/min, respectively, the coefficient of concordance in relation to the aggregate volume of applied fertilizer among all outlets of the blender is less than 13%, suggesting the evenness of the mixture conformed to applicable requirements. As for the mixed fertilizer and the three separate fertilizers, the difference, as a percentage, among their respective aggregate volume of applied fertilizer is less than 7.8%, suggesting stable continuity of the fertilizer and that the mixer met the requirements of continuous mixing.