Structure Optimal For Hydrocyclone On Removing The Fine Particles

According to the guide and adjust fluid theory, we designed aα-Pa hydrocyclone with long curve cone and screw board in order to solve the solids'separation questions that diameter was lager than 5μm in the seawater suspension. The works are as following:Firstly, the Reynolds stress model (RSM) with CFD simulation software Fluent6.2 was used to analyse the distribution law of velocity vector, tangential velocity, axial velocity and other parameters of theα-Pa hydrocyclone. The influence of overflow tube, long curve cone and screw board on separation efficiency was studied. The moving behavior of solid particles in theα-Pa hydrocyclone was studied with the stochastic model of interaction with continuous phase elementarily, and the moving behaviors of different diameter particles were predicted. The interaction between particles moving behavior and field was found through analyzing particles moving behavior. The simulation results shown that: the extential form overflow tube can vent fluid from the hydrocyclone at low pressure, and reduce the energy consumption; the inside components of theα-Pa hydrocyclone can avoid the sand ring effect, because they can guide and adjust fluid action; the long curve cone can extend the flow time of the liquid,which is benefit for the separation of fine particles.Secondly, according to the simulation results, the general hydrocyclone and theα-Pa hydrocyclone which had the same size were produced. Using the mixture of fine sand and water as feed material, the separation performance of two hydrocyclones was compared. The experiment results shown that: compared with the general hydrocyclone, not only the flow field of theα-Pa hydrocyclone was more steady, but the energy cost and the pressure drop were lower. Under the same operation condition, the separation efficiency of theα-Pa hydrocyclone was higher than general hydrocyclone. The separation efficiency of theα-Pa hydrocyclone about 5μm was up to 90% ,and the cut off diameter was 1.3μm when the split ratio was 0.87. Using the seawater as feed material, the separation performance of theα-Pa hydrocyclone was tested. The locale experiment results shown that: when the seawater turbidity value was low, the change extent of seawater was invisible after disposed by theα-Pa hydrocyclone, because the main substance in seawater is colloid whose density is similar to seawater. When the seawater turbidity value was high, the change extent of seawater was visible after disposed by theα-Pa hydrocyclone, because the main substances in seawater include colloid and solid suspension. The separation efficiency of theα-Pa hydrocyclone about fine particles was high, which reached the demand of separation granularity and efficiency before membrane disposal.Finally, based on the equilibrium orbit theory, the mathematical formula of cut-off diameter d50 about theα-Pa hydrocyclone was founded. The computation results shown that: the experiment value about cut-off diameter d50 basically tallied with the computation value.