Research On Flocculation Sedimentation Of Coal Slurry Based On Self-preserving Coagulation Dynamics

So this paper designed a new reactor based on self-preserving coagulation theory,which had small ground occupation area and had a good effect on flocculation.The effects of different flow rate and reactor structure on flocculation were investigated,at the same time the optimal equipment structure and the optimal hydraulic conditions were explored.Firstly this paper deduced computational method of structural parameters of reactor according to self-preserving coagulation dynamics theory.Then structural parameters of reactor were calculated to simulate and design when G0 was 300s-1,slurry concentration was 40g/L and particle size was 0.02 mm.At the same time the influence of the reactor structure on flocculation effect was explored by enlarging the outer diameter of the screw and changing the length of the channel.Numerical simulation results showed that along the direction of Z axis,the velocity of fluid decreased gradually.The turbulent kinetic energy and effective energy consumption on the center surface indicated that a number of coils and large inlet velocity were more favorable for flocculation.The velocity gradient obtained by theoretical calculation is the same as that obtained by simulation which decresed gradually,but the value of theoretical calculation was larger than simulation.The rationality of the design of reactor is also verified.The flocculation test results proved that for the same flocculation reactor,with the increase of feeding rate,overflow turbidity decreased,then increased;and the underflow concentration increased first and then decreased So there existed optimal initial velocity which too low or too high feeding rate was harmful to the flocculation process.The effect of large diameter and multi helix reactor was better,and the optimal initial velocity is 0.151m/s by comparing the results of different flocculation reactors.Combined with experimental results and simulation results,we knew that volume weighted turbulent kinetic energy between 0.0068m2s-2~0.0027m2s-2,and volume weighted effective energy consumption between 0.166m2s-3~0.042m2s-3 can help to ensure a better flocculation effect.The particle size analysis results showed that when initial velocity was 0.151m/s,for the same model,the average particle size and fractal dimension of flocs gradually increased with the flow of particles in the spiral flow channel,with no obvious shear breakage.In this paper,when the reactor structure parameters are: the height of the outer cylinder 1500 mm,outer diameter 100 mm,inner diameter of 80 mm,the fractal dimension of final floc was largest,reaching to 2.1103,which was the best density and settlement.So the flocculation reactor which was designed on basis of the self-preserving coagulation dynamic can meet the requirement of the hydraulic condition of the coal particle settling process.