Modified screw conveyor-mixers - Discrete element modeling approach

Abstract

Screw conveyors are widely used in the food industry, building construction and mining companies, chemical, agricultural and processing industries, mostly for elevating and/or transporting bulk materials over short to medium distances. Despite their apparent simplicity, the improvement of the transport parameters is a very demanding task and designers usually have to rely on data obtained from empirical investigations. In this paper, fifteen horizontal single-pitch screw conveyors with modified geometry and the different lengths were investigated for premixing action, during the transport of materials. All investigations were performed experimentally and numerically, by using Discrete Element Method (DEM). The influences of screw length, observed geometry variations and different types of screw design, on the performances of the screw conveyor-mixer during material transport were explored. The auxiliary mixing action (used to improve the mixing process) was achieved during the transport of the material. The geometry of the screw conveyor is changed by adding three complementary helices oriented in the same or the opposite direction from screw blades. The particles of the material being transported tumble down from the top of the helix to the next free surface, and that segment of helix was used for additional mixing action. According to experiments and DEM analysis, the particle path length is increased, with the observed modification of screw conveyor, and the improved geometry could be determined for increasing the quality of mixing. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.