Numerical simulation and experimental study on ultrafine powder spiral transportation degassing

Aiming at the problems of ultrafine powders of high air content and environmental pollution, low measurement accuracy and low efficiency in packaging and filling process, the research on degassing spiral powder transportation was carried out. Discrete element method and physical experiment method were used to simulate and test the mass flow rate, material density and dust concentration of packaging environment of equidistant spiral and degassing (variable pitch) spiral powder transportation, and the transportation effects of equidistant spiral and degassing spiral were analyzed.Simulation and test results show that the average mass flow rate of the degassing screw is 0.639 kg s-1 with the same screw outer diameter, inner shaft diameter, length and rotational speed, and the flow rate fluctuates with the percentage of fluctuation in the range of 7.19% - 10.02%. The degassing spiral increases the mass flow rate of the feeding device and reduces the flow fluctuation,and the maximum densification of the material was increased by about 7.25%. With the increase of rotational speed, the environmental dust lifting degree of both spiral filling processes increased, but under the same rotational speed, the dust lifting degree of the outlet of the degassing spiral was significantly reduced compared to the isometric spiral, and the rotational speed was increased from 80 to 120 r min-1, the maximum dust lifting degree of the isometric spiral was 37.88%, and the average dust lifting degree of the maximum was 25.59%, and the maximum dust lifting degree of the degassing spiral was 21.59%. The maximum dust lifting degree of the degassing spiral is 21.18%, and the maximum increase of the average dust lifting degree is 14.49%. Degassing spiral device effectively realises efficient and clean packaging of ultra-fine powder.