الفهرس 
Elements of belt conveyor systems
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Abstract
Belt conveyors are one of the most common systems in the field of bulk materials handling. Such systems are typically used to convey bulk materials such as coal, cement, ores and grains throughout processing facilities or to storage or shipping facilities. Belt conveyor systems may extend for tens of kilometers of length with an approximate maximum standard belt width of 275 centimeters (108 inches). Driving such systems consumes energy at high rates and accordingly results in emitting huge amounts of pollutants in the environment.
The study aims at analyzing the most significant factors affecting power consumptions in such systems and attempting to find solutions that can lower power consumption in the design phase. As a first step, the most influential factors on power demand of belt conveyors were studied and summarized based on literature review. These factors can be classified to system design parameters (as idler roll material, trough angle, idler spacing, idler roll diameter and idler roll bearing type), operational conditions (as belt speed) and environmental conditions (as ambient temperature). Calculations of the power demand of a belt conveyor system are prepared under different working conditions, based on common inputs applied in the mining industry. The calculated values were closely examined in a factorial design to investigate the significance of these factors and their interaction effects on power demand.
Based on this factorial design study, the influential factors could be narrowed down to idler spacing, idler roll material and diameter, idler spacing, belt speed and ambient temperature. Accordingly, Finite Element Method (FEM) was used to study the effect of some of these factors on the Indentation Rolling Resistance (IRR), one of the major resistances contributing to increased power demand in horizontal belt conveyor systems. In order to construct the FE model, material data were defined through a set of experimental characterization methods, involving mechanical testing of tensile properties, density measurements and Dynamic Mechanical Analysis (DMA).
A pilot study FE model was prepared to assure that results are accurate in comparison to experimental results for a similar application. The pilot study FE model was used to compare indentation rolling resistance of a flat belt conveyor system against experimental results reported in literature. The applied model proved good agreement of 93% on average with the experimental data. Accordingly, the FE approach was evaluated to be of a satisfying accuracy to be further adopted for the FE analysis of troughed belt conveyor systems under pre-defined conditions.
FE results for troughed belt system show high coherency with the theory, where using larger idler rolls and smaller idler spacings result in lower IRR. On the other hand, assigning lower belt speeds at constant belt capacity results in higher IRR due to higher loads imposed on the belt under these conditions. This does not match with the generic rule that power demand increases with increasing belt speed.
Based on the results of the current study, power demand savings can be achieved in long belt conveyor systems through increased idler roll size, using relatively narrow idler spacing and operating such systems at relatively high belt speeds. Conveyor belts should be designed in a way that optimizes the various operational parameters of interest while considering the economic value as well.
Future studies should be conducted to study the effect of belt speed at a constant bulk material loading and include the economic aspects of idler spacing to have a clearer image that can contribute efficiently in lowering power consumption for belt conveyor systems and reducing costs at the same time. Future studies should also be directed towards the effect of a wider range of idler spacing and idler roll material on power demand. In order to simulate the effect of bulk material flexure on power requirements, Discrete Element Modeling (DEM) can be coupled with FEM.