Sensor-based sorting is a machine vision application that has found industrial application in various fields. An accept-or-reject task is executed by separating a material stream into two fractions. Current systems use line-scanning sensors, which is convenient as the material is perceived during transportation. However, line-scanning sensors yield a single observation of each object and no information about their movement. Due to a delay between localization and separation, assumptions regarding the location and point in time for separation need to be made based on the prior localization. Hence, it is necessary to ensure that all objects are transported at uniform velocities. This is often a complex and costly solution. In this paper, we propose a new method for reliably separating particles at non-uniform velocities. The problem is transferred from a mechanical to an algorithmic level. Our novel advanced image processing approach includes equipping the sorter with an area-scan camera in combination with a real-time multiobject tracking system, which enables predictions of the location of individual objects for separation. For the experimental validation of our approach, we present a modular sorting system, which allows comparing sorting results using a line-scan and area-scan camera. Results show that our approach performs reliable separation and hence increases sorting efficiency.

The discrete element method can be used for modeling moving granular media in which heat and mass transport takes place. In this paper the concept of discrete element modeling with special emphasis on applicable force laws is introduced and the necessary equations for heat transport within particle assemblies are derived. Possible flow regimes in moving granular media are discussed. The developed discrete element model is applied to a new staged reforming process for biomass and waste utilization which employs a solid heat carrier. Results are presented for the flow regime and heat transport in substantial vessels of the process.

Based on LEAT’s discrete element codes, granular flow and mixing on conveying equipment are studied in two and three dimensions. Discrete element simulations, which are briefly introduced, provide detailed information on particle positions and velocities over time. This information is used to derive quantities characterizing the dynamic process of mixing. The main focus of the study presented is the mixing process of inhomogeneous particle ensembles on different grate types. For this purpose, the introduced mixing parameters are used to compare the mixing in a 3D situation with the corresponding 2D approximation on identical grates and to compare different grate designs in two dimensions.

Visual properties are powerful features to reliably classify bulk materials, thereby allowing to detect defect or low quality particles. Optical belt sorters are an established technology to sort based on these properties, but they suffer from delays between the simultaneous classification and localization step and the subsequent separation step. Therefore, accurate models to predict the particles' motions are a necessity to bridge this gap. In this paper, we explicate our concept to use sophisticated simulations to derive accurate models and optimize the flow of bulk solids via adjustments of the sorter design. This allows us to improve overall sorting accuracy and cost efficiency. Lastly, initial results are presented.

The multiple hearth furnace is a common industrial reactor for the thermal treatment of particulate material. The present contribution concentrates on a numerical analysis of contact heat transfer on a batch-operated single floor of a multiple hearth furnace employing the Discrete Element Method (DEM). The particles are agitated on an electrically heated circular floor by a single rotating rabble arm equipped with three flat blades. Blade angles have been varied from 0° to 90°. The DEM simulations (particle mechanics and contact heat transfer) were validated against experimental data. The transient heating of 20 mm diameter polyoxymethylene (POM) spheres was analysed. As the simulations did not consider natural convection inherently leading to time-varying heat losses, an averaged heat loss parameter was determined to represent heat dissipation from the particles to the surrounding gas and incorporated into the DEM simulations. With this approach, a good agreement with measurements was obtained. The DEM simulations and experiments do not show a large influence of the blade angle on the temporal evolution of the mean particle temperatures. However, the frequency distribution of particle temperature is dependent on the blade angle, revealing an increase in the standard deviation of the frequency distribution with an increasing blade angle.