Abstract
The effectiveness and precision of transporting wood chips on the transport trailer or hopper depends on an inclination angle, a conveyor belt speed, and length. In order to devise a methodology aiding designing and the selection of technical and performance parameters (aiding the settings of conveyor belt sub-assemblies), the authors carried out the simulation tests concerning wood chips transport on the belt conveyor and their outlet. For the purposes of these tests, a simulation model was performed in the Rocky DEM (discrete element method) software in the numerical analysis environment and compared to analytical tests. The tested wood chips were taken from cherry plum branches chipping processes (Prunus cerasifera Ehrh. Beitr. Naturk. 4:17. 1789 (Gartenkalender 4:189-204. 1784)), out of which seven basic fractions were separated, which differed mainly in terms of their diameter from 5 mm to 50 mm and the length of 150 mm. The article presents the results of wood chips ejection distance in the form of the 3D functions of wood chips ejection distance depending on the conveyor belt inclination angle and belt speed. The results are presented for five conveyor belt lengths (1 m, 2 m, 3 m, 4 m, 5 m). The tests also involved the conveyor belt inclination angle in the range from 10° to 50° and the belt velocity in the range from 1 m/s2 to 5 m/s2. The numerical test results demonstrate higher average values of wood chips ejection distance than designated in the analytical model. The average arithmetical difference in the results between the numerical and analytical model is at the level of 13%.
Highlights
The analytical model does not provide for the aerodynamic resistance of wood chips; with such an assumption, each type of wood chips was ejected at the same distance
CAD (Computer Aided Design) 3D model of the stand, the conveyor belt end height was determined from the hopper bottom for all five lengths and the inclination angle of the conveyor belt (Table 3)
The simulation of correct wood chip transport and outlet from the conveyor belt is presented in Figure 8a, whereas, with higher velocity of the conveyor belt, wood chips are susceptible to the higher probability of wood chips rotation and not reaching the set velocity at the belt conveyor outlet
Summary
Chippers for the industrial production of biomass, with high capacity (indicated in scientific publications on the power range from 130 kW to 900 kW [6]), have the wood chips outlet system based on the forced motion of the cutting mechanism [2,3,7,8,9,10,11]. Chippers used on urban areas for tree care in parks, gardens, and by-road surfaces are low power machines (Figure 1). The main task of their drives is supplying the cutting mechanism with power; whereas wood chips transport is aided by the conveyor belt system (Figure 2). The popular designs of low power chippers
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