Discrete Element Method Simulation And Experimental Investigation On Particle Flow Behaviors In A Gas-solid Fludizied Bed

Fluidized beds are widely applied in the industrial processing,and attract more interests from researches for guiding industrial reactor design.However,most researches focusd on the dry particle system.In fact,the presence of liquid is inevitable,which results in the differernce s between dry and wet particle flow behaviors.Thus,in this work,the wet particle flow behaviros are simulated based on Discrete Element Method(DEM)in single spouted bed,double-spout fluidized bed and riser.Besides,the wet particle flow behaviors are investigated by experimental measurement in a single spouted bed.In the work,a modified DEM model has been built to investigate the wet particle flow behaviors.Based on discrete element soft-sphere model,a liquid bridge model has been added to describe the wet particle flow behaviors.Besides,a dynamic Large Eddy Model(LES)is used to investigate the influence of gas turbulent motion on particle flow behaviors in a riser.What's more,the parameter is well chosen to reflect the particle flow characteristics near the walls.Based on the Particle Image Velocimetry(PIV)system,the mearment on dry and wet particle flow behaviors are conducted in a spouted bed,and the DEM numerical simulation is carried out corresponding to the experimental setting.The experimental results show that the particle flow behviors are influenced by cohesive liquid obviously.With an increasing of liquid content,particles are more difficult to be fluidized and form particle agglormerates.Besides,the gas channel is formed near the gas inlet in the wet particle system,a nd the particle agglomerates attach to the walls under the effect of cohesive liquid.The DEM model built for the wet particle system is applied to investigate the particle flow behaviros in single and double spout fluidized bed s.The dry particle flow behaviors are investigated in a double spout fluidized bed first.The effect of liquid content on particle is conducted.Besides,the comparison of particle flow behaviors is investigated under the effect of gas inlet numbers.By contrast,the mixing index and particle colliding percentage increase with more gas inlets,which is meaningful for designing the industrial reactor.The numerical model is built to investigate the dry and wet particle flow behaviors in a riser.For the riser,particle flow behaviors are influenced by cohesive liquid obviously.The results show that particles are distributed in the bottom of riser and near walls.With an increasing of liquid content,particle granular temperature increased with more violent particle fluctuation.