Measurement of the bulk material distribution length on a conveyor belt surface guided on a three-roller idler housing

Belt transport is an effective and one of the most widespread methods of transporting bulk materials in various industrial sectors. Properly designed and operated belt conveyors significantly increase productivity, reduce operating costs and minimise the risk of accidents. To ensure the efficient and reliable transport of bulk materials by belt conveyors, it is essential to know the length of their distribution on the surface of the conveyor belt, especially at inclinations exceeding normal operating conditions. Determining the length of material distribution is key to optimising conveyor design, efficient operation, and preventing operational failures such as material backsliding. The paper verifies an original method of measuring the bulk material length distribution on a conveyor belt’s surface, guided on a three-roller idler housing. The measurements were carried out because the ISO 5048 standard does not provide instructions for determining the volume of transported material for a belt conveyor, the inclination angle d [deg] of which exceeds the dynamic angle of discharge Q [deg]. The measurement was carried out for various conveyor angles of inclination, the conveyor belt width and the height of the partitions for two different types of bulk materials (wheat, river gravel). The experiments were carried out at a conveyor inclination significantly exceeding a permissible angle of inclination, which caused the material to slide back on a conventional conveyor belt. Transverse partitions were installed on the conveyor belt to eliminate this effect and were fixed at regular intervals. The volume of transported material dose spread on the surface of the conveyor belt retained by a transverse partition of a known height can be analytically calculated according to the formulas given in this article. Due to the practical impossibility of carrying out measurements in actual operating conditions, a laboratory device was designed, which represents a section of a belt conveyor with a support system and a conveyor belt with partitions. The device allows simulating 3 different middle roller lengths from 300 to 500 mm. During the measurements, the angle of inclination of the conveyor longitudinal axis can be further changed to 20 to 70 degrees and the height of the transverse partition to 0 to 100 mm. The experimental results confirmed the functionality of the proposed method and were validated by theoretical calculations. The difference between the experiments and the theoretical calculation is for the measured material “food wheat” in the range of 7.2 % to 12.6 % and for the material “river gravel” in the range of 2.8 % to 14.1 %. The designed laboratory device thus provides a reliable platform for experimental measurement and analysis of bulk material length distribution on the conveyor belt’s surface guided on the three-roller idler housing.