Modelování procesů partikulárních hmot v aplikaci na vibrační dopravu

Abstract

This dissertation thesis deals with the use of bulk material modeling using the Discrete Element Method (DEM) for applications in the field of vibration technology. The area is narrowed to vibration processes using a helical vibration motion or emptying storage devices under the action of external energy in the form of screw vibrations. The aim of the work is to extend the use of helical vibration motion modeling to the construction industry, agriculture or waste materials processing. Within these selected areas of application, representative samples were selected, which are sand, maize and pellets made from wooden sawdust. Mechanical and physical properties and interaction parameters were measured for selected materials, which belong to the group of basic input parameters in the EDEM simulation environment. The next part is devoted to calibration of selected materials with subsequent validation of simulation experiments using the EDEM program. To validate the vibration motion in the shape of a spiral, a prototype of a vertical vibratory conveyor was designed, which is used for the transport of bulk and piece materials. The main advantages of this type of conveyor include, for example, high headroom, high transport distance, small space dimensions, easy regulation of transport performance, etc. The vertical vibrating conveyor was subjected to operational tests. Using the Olympus I-SPEED 2 high-speed camera, true waveforms and oscillation parameters have been detected for different operating settings. The obtained information was subsequently used as input parameters of the spiral vibration motion into the EDEM simulation environment. The final part of this work is focused on application experiments using modeling of processes using the DEM method. The first application concerns the transport of maize on a vertical vibratory conveyor at different operating settings. The maize transport process was validated using DEM simulations. The second application is focused on the cooling of wood sawdust pellets during transport on a vertical vibrating conveyor. Another application relates to optimizing the discharge of sand from the dosing tank. On the basis of the information obtained about sand, which was categorized as cohesive, a dosing tank was designed. Using the DEM simulation it was found that the sand could not arbitrarily loosen from the storage space of the container. External energy in the form of screw vibrations was applied to the dosing tank structure. This solution was applied with a positive effect in real operation. The last application experiment is the optimization of the sieve separator using the DEM method. DEM modeling of transport and storage processes has proven to be a very effective tool for designing new or optimizing existing vibration technology devices. DEM simulations can be used to verify the behavior of bulk materials on a newly designed transport or storage facility. Parameters of optimal vibration motion can be obtained from verified simulations, which are the shape and extent of oscillation, frequency of oscillation or magnitude of oscillation amplitude.