Hydrodynamics Model And Behavior Of Liqui-Solid Fluidized Bed Electrochemical Reactor

Liquid-solid fluidized bed electrochemical reactor represents the charming application tendency in effluent treatment because it is quality of giant reactor surface and mass transfer rate, more easily and more friendly in operation and scaling up of the reactor. The potential distribution of liquid, the potential and its fluctuate of particles in bed are the key to the study on the reactor properties. The regularity of particle potential fluctuates and hydrodynamic properties of electrochemical fluidized bed were obtained in opinion of different scales.A set of apparatus for researching fluidized bed was established. The reactor is the structure of two dimension liquid-solid fluidized bed, and were made of perspex plate, the solution velocity in bed is 0.0015 m/s~0.01m/s. The method of the two-channel optical fiber reflecting for particle velocity measurement was adopted to get the time sequence signal of moving particle velocity in the fluidized bed. By means of cross-correlation analysis, the average velocities of particles at theselected point were obtained from the time sequence signal of two-channel fiber, and the average voidage of the bed at the measuring point from the signal of single channel fiber. The result of the experiment show that the fluidized particle velocity is the parabola distribution in radial direction, and the gradient of the particle velocity in radial direction increase with the increasing of liquid velocity, the voidage of bed is uniform in both axial and radial direction, and the average of voidage increases linearly with the increase of apparent liquid velocity.The assumption of the model of the fluidized bed for the imitation liquid of the solid particle and the liquid in bed are that: regarding particle flow and the liquid flow as continuous mediums, and the voidage were uniform distribution at all points of the bed. In the term of the theory of hydrodynamics, the two-phase flow model of the liquid velocity and solid particle cycle flow was established.The model reveals that, the contribution of liquid velocity is parabola in radial, the particle velocity distribution in radial is parabola too; at X=0.577, Vy =0; X<0.577, Vy>0; X>0.577, Vy<0;with increasing of liquid velocity, the average voidage of bed increases, however the liquid effective viscosity decreases and the effect between particle flow and flow of sap be weaken. It is acceptedly agreedment that the result of model predicts meet with that of experiment.A fluidized bed electrochemical reactor and a measurement system of potential signal were designed and built. The V-I curve of K3[Fe(CN)6] reduction reaction in different expansive ratio and the I-t curve in different K3[Fe(CN)6] concentration were achieved. The result of the experiment shows that: there are two effects on the reaction current, which are in reverse, one is the mass transfer, the other is the collision frequence of fluidized particles. The increases of liquid velocity enhance the mass transfer between the solid and the liquid, however, on the other hand, decrease the collision frequencies.