GAS-PARTICLE FLOW IN A COMPARISON OF MEAS UREMENTS AND SIMULATIONS

High mass flow rates of bulk solids can be separated from gases and cl assified with high sharpness in a Zig-Zag classifier. This paper descr ibes investigations of the gas-solid flow in such a classifier by meas urements, experimental observation and numerical simulation. The singl e phase gas flow field was visualized by injecting tracer particles (s moke) into a model classifier in order to identify characteristic area s in the flow field. Representative velocity profiles were measured by Laser-Doppler-Velocimetry (LDV). in addition, the single phase gas fl ow field was numerically simulated with different turbulence models in two and three dimensions. The bulk solid used for separation in the c lassifier consisted of spherical glas particles with diameters from 0. 1 to 1 mm. The trajectories of single particles and particle clusters were visualized and evaluated. The separation characteristic which dep ends on the gas flow rate and the dispersed phase loading was describe d quantitatively by the separation cut point and separation efficiency . Additionally, at low loadings particle trajectories were simulated b y means of a particle tracking technique based on the Lagrangian appro ach for calculation of the separation function. The results from numer ical simulation and measurement will be compared and deviations will b e discussed. On behalf of the results of measurement and numerical sim ulation, the state of the art in modelling dispersed gas-solid flows i s judged and necessary improvements are shown.