| Organosilicon materials are widely used in electronics,building materials,textiles,transportation,and other fields due to their excellent properties.Typically,organosilicon materials are formed by hydrolysis and Polycondensation of organosilicon monomers,and then polycondensation of the resulting oligomers.So far,the most economical and effective method for producing organosilicon monomers is still the direct method.The whole reaction process is carried out in a fluidized bed.Therefore,the process parameters and structural design in the fluidized bed are closely related to the conversion rate of silicone monomer.As an important component of the fluidized bed,the gas distributor plays a key role in the fluidization and the stable operation of the fluidized bed.Its structural characteristics will affect the mixing between gas and solid particles,and then affect the quality of gas-solid fluidization in the bed.In addition,as an important part of the fluidized bed,the gas distributor plays a key role in the fluidization and stable operation of the fluidized bed.Its structural characteristics affect the mixing between gas and solid particles,which in turn affects the quality of gas-solid fluidization in the bed.To improve the quality of gas-solid fluidization in the bed and increase the conversion rate of organosilicon monomer,this paper studies the fluidization characteristics of organosilicon monomer synthesis fluidized bed and the optimization of gas distribution based on two-fluid model（TFM）.The main research contents are as follows:（1）The existing literature on gas-solid fluidization characteristics based on TFM is sorted out,and typical methods for analyzing gas-solid fluidization characteristics are summarized.On this basis,a new idea for analyzing the gas-solid two-phase flow is proposed,that is,the hydrodynamic characteristics of gas-solid two-phase flow are analyzed by using the correlation formula of gas-solid two-phase flow evolution process combined with particle volume fraction cloud diagram,particle volume fraction distribution curve and particle velocity distribution curve.（2）In this study,TFM is used to study the effects of different gas velocities and particle sizes of silicon powder on fluidization characteristics under a certain opening ratio.On this basis,the relationship between the particle size of silicon powder and the opening ratio of the gas distribution is further explored,which provides theoretical guidance for the selection of process parameters and the opening ratio of the gas distribution.The results show that the particle flow pattern is more stable when the inlet gas velocity is 1.1 times the minimum fluidization velocity and the particle size of silicon powder is 4.67×10-5m,which is helpful for gas-solid mixing.The opening ratio of the gas distribution is negatively correlated with the particle size of the silicon powder.The gas distribution with a low opening ratio is used to fluidize the silicon powder with a larger particle size,and the gas distribution with a high opening ratio is used to fluidize the silicon powder with a smaller particle size,which can help the gas-solid mixing and improve the fluidization quality.（3）This study uses TFM and proposes a design formula for the gas distributor to optimize the gas distributor.It is proposed that the pressure drop of the gas distributor,the velocity nonuniformity coefficient,the relative standard deviation of the solid holdup,and the solid particle dispersion coefficient are used to evaluate the performance of the gas distributor.The results show that the performance of the gas distributor is significantly improved when the opening ratioΦ=0.53%is optimized toΦ=0.18%,in which the relative standard deviation of the solid holdup is reduced by22%,and the solid particle dispersion coefficient is reduced by 40%.On this basis,aiming at the optimized gas distribution,the influence of different arrangements of vent holes on gas-solid fluidization characteristics is studied.The results show that the circular arrangement of the vents is helpful to the mixing of gas and solid and improve the fluidization quality. |
