Abstract: A double-layer belt conveyor, which conveys coal on the upper belt and ash powder on the lower belt, is placed higher than the conventional singe-layer belt conveyor. To determine the most appropriate height of the rain shield to prevent ash powder from blowing out under strong crosswinds (velocity is 17 m/s), the Fluent software is used to numerically simulate the distribution of the flow fields and the dust concentration fields within the rain shield with or without crosswind based on the theory of gas-solid two-phase flow. The calculation results show that crosswinds strengthen the vortex formed between the double-layer belts and the ash powder may thus be blown out. When the crosswind velocity is 17 m/s, the vortex formed is not too strong and the ash powder will not be blown out of the rain shield. Under crosswind conditions, there is wind blowing with very high velocity(up to 55 m/s) on the top of the rain shield; as such, the stress exerted by the strong winds should be considered in the process of designing the strength of the rain shield. In the presence of crosswinds, the dust concentration in the rain shield is the highest at the junction of the coal conveying belt and coal pile, and is the second highest at the junction of the ash powder conveying belt and ash powder pile. When the crosswind velocity is 17 m/s, the dust concentration outside the rain shield is less than 4×10^-6 kg/m³, which meets the requirements of the Coalmine Safety Regulations. 

Key words: double-layer belt conveyor, rain shield, flow field, dust concentration field, numerical simulation