空气-SRNA-4催化剂磁稳定床的流动特性

床层压降、最小流化速度、固含率及其分布和气相返混系数是气固磁稳定反应器放大与优化所必需的基础数据.采用压降法、光电法及瞬态点源示踪技术试验研究了以SRNA-4催化剂为固相的气固磁稳定床的流动特性.试验结果表明:最小流化速度、最小流化状态下的床层空隙率与磁场强度无关;固含率的径向分布基本均匀;磁场强度的增大抑制了颗粒的运动,使得局部固含率略微增加;空塔气速的增加促进了气固磁稳定床的膨胀,使得固含率减小;粒径较小时,随磁场强度及气速的变化贝克来数(Pe)变化不大;粒径较大情况下,Pe随气速增大而减小,随着磁场强度的增大,先增大后减小.试验获得了最小流化速度、固含率和床层高度的关联式,预测值与试验值吻合良好.

Hydrodynamics of Air-Catalysts of SRNA-4 in Magnetically Stabilized Bed

Pressure drop,minimum fluidized velocity,solid holdup,local solid holdup distribution and gas phase backmixing are fundamental to the scale-up design and optimization of gas-solid(G-S) magnetically stabilized reactors.In this article,the hydrodynamics were studied using the pressure drop method,the photoelectric method and the transient point source tracer pulse input technique for the G-S magnetically stabilized bed taking the ferromagnetic amorphous alloy catalysts of SRNA-4 as the solid phase.The minimum fluidized velocity and the related bed voidage were observed to be independent of the magnetic field.The radical distribution of the solid holdup was uniform,and the local solid holdup increased owing to the inhibition of the particle movement by the magnetic field.However,increasing the superfacial gas velocity can promote the expansion of the GS bed,and decrease the solid holdup.For small particles,Pe number did not change greatly as the magnetic field and gas velocity changed,while for large particles Pe number decreased as the magnetic field increased,and the increase of magnetic field made the Pe number increased at the beginning then followed by decreasing.Based on the experimental data,the correlated equation was obtained to estimate accurately the minimum fluidized velocity,solid holdup and bed height.