Study On The Influence Of Air Distribution Structure On The Tow-phase Flow Behavior Of The Spout-fluid Bed

Spout-fluid bed is a new furnace improved by spouted bed.It not only has the less dead region features like fluidized bed,but also has the good fluidization characteristics of spouted bed,and it has been widely used in industry by the ability of better adjustability and adaptability than conventional spouted beds.So far,the fluid flow characteristics of spoutfluidized bed have not been studied systematically.In most cases,the structure selection and parameter optimization can only be based on experience.So it is necessary to carry out numerical simulation and structural optimization about spout-fluid bed.The air distribution mode and air distribution plate of spouted fluidized bed play an important role for bed flow characteristics.the solid particles will be uneven distributed and the solid fluidized will be inefficient if the flow characteristics is unstable by the unsuited air distribution mode and air distribution plate,so it will be very significant if you can study the influence of the air dtribution mode and air distribution plate on the flow characteristics.First,this paper used the way of numerical simulation to study a small spout-fluid bed,compared the result of different turbulence models and different drag force models,and find the accurate numerical simulation by the comparison between the simulation results and the experimental data.Then this paper simulated the large spouted fluidized bed in practical,study the effects to the flow pattern by different angle of the air distribution,the effect to the bed flow pattern by changing the spout wind speed,the fluid wind speed and the angle of the fluid wind.Main research results are summarized as follows:(1)The experimental apparatus and conditions were simulated using Euler-Euler twofluid model,then compared the results of different drag force models(Gidaspow model,Syanlal-O'Brien model and Wen-Yu model)and different turbulence models(Standard k-? turbulence model,RNGk-? turbulence model and Realizablek-? turbulence model)with the experimental data and find the best suitable drag force model and turbulence model.(2)The simulation of a large spout-fluid bed under different air distribution plate angles was carried out.It was found that the fluided bed which has the smaller angle distribution plate have the larger gap area,the less die area and the smaller jet diameter,but the efficiency is low and the pressure drop is high.Considering the homogeneity of concentration distribution and the pressure drop of bed,the air distribution plate is preferably between 75 ° and 90 °.(3)The effect of spouting wind speed on the flow characteristics of spout-fluid bed was studied.Find that the jet diameter increases,the jet penetration increases,the fountain height increases,and the gas-solid mixing capacity increases as the spouting wind speed continues to increase.But if you continue to increase the spouting wind speed,the particles will be blown out by the gas.Therefore,the spouting speed should be controlled within a certain range.For the object of this paper,the velocity of spouting should be controlled between 30m/s-35m/s.(4)The effect of fluidization velocity on the flow characteristics of spout-fluid bed were investigated.Find that the particle concentration decreases and the gas in the annulus area increases into the sparge zone,the center jet capacity increases,and the gas-solid cycle effect is enhanced.But if you continue to increase the fluidization of the wind,it will form a larger bubble in the annulus area and the bed becomes very unstable.Therefore,the fluidization wind should be controlled within a certain range.For the object of this paper,the fluidized wind speed should be controlled at about 10m/s.(5)For the spout-fluid bed studied in this paper.It is found that when the angle of fluidized wind is radial and axial,the particle concentration in annulus area is high,and the dead zone is formed easily.The mixing capacity of annular gap and spouted area is poor,which is disadvantageous to the operation of fluidized bed.When the incident direction is normal,the annulus area dead zone situation is greatly improved and the gas-solid mixing capacity is enhanced.Therefore,for the object of this paper,the effect will be best if the angle is along the normal of the cloth palte.