Design And Optimization Of Grain Pneumatic Conveyer Feeder

In recent years, as the rapid development of grain industry in China, we are faced with numerous problems of grain transportation and storage. How to design and optimize the grain pneumatic conveying system is on the top agenda. The bottom of the feeder is an essential component of pneumatic conveying system. It plays a vital role in conveying food material into the pneumatic conveying pipeline and mixing it with the air flow. The performance of the feeder directly affects the working efficiency of the entire pneumatic conveying system. There is a certain grain pneumatic conveying system. The lacking of a rational feeder structure leads to low mass flow, small capacity, low material velocity and inadequate conveying distance. Based on the gas-solid two-phase flow theory and Fluent software discrete model, we studied the impact of various feeder structure on conveying process through pneumatic conveying mechanism analysis. By analyzing the related parameters which affect the performance of the feeder, we devised optimized feeder structure through simulation calculation. And in view of the general low-velocity conveying and low capacity bottom feeder in the existing market, an onoff feeder with controllable blanking material flow are proposed and the main research results are as follows:(1)By using the Fluent software DPM model to simulate the real working condition of the feeder and analyze the conveyi ng state of materials, we can build the bottom feeder mathematical simulation model of grain suction machine and effectively find the optimal structure parameters of the feeder, thus considerably reducing the research and development cycle of pneumatic gra in elevator, cost, and whatnot.(2) The simulation experiment of bottom feeder of the pneumatic grain elevator, emulated by the Fluent software DPM model, shows that the centor distance is the key factor that determines material velocity, while area ratio is the key factor that affects the concentration of material particles. The wider the distance between venting outlet and material inlet is, the worse the performance of the bottom feeder is, the weaker the ability of high-speed gas to carry matrial particles is. In this case, grain cannot be conveyed into material inlet. On the other hand, the more narrow the distance is, the high-speed gas which carries material particles becomes too powerful that proves to be counterproductive. When the center distance is 140 mm, the area ratio is 1:3, the diameter of the blanking mouth is 120 mm, the venting outlet particle velocity will reach 62.8 m/s, mass flow rate is 21.3 kg/s, and maximum capacity will reach 40 t/h. In this case, the feeder is in good performance.(3) In view of the disadvantages of traditional feeder, an onoff feeder was put forward. When the blanking mouth is closed, materials will be compacted in the buffer room. Then the compacted matrials becomes a closed mixing chamber with a stable air-filled cavity. When we open the blanking mouth, the internal flow field of onoff feeder is stable, with no back-flow phenomenon. Feeding trajectory is smooth and material conveying is continuous, with no irregular movement. When the blanking mouth is wide open, the venting outlet particle velocity will reach 76.3 m/s, mass flow rate is 28.2 kg/s, and maximum capacity will reach 60 t/h. To adapt to different capacity requirements, we can use the regulating handle of onoff feeder to manipulate the material mass flow.