Simulation Study On The Separation Of Natural Gas Hydrate Slurry By Dynamic Hydrocyclone

The exploitation and utilization of natural gas hydrate resources have become a frontier of technological innovation in the world.Our country's pilot mining project for weakly cemented and non-diagenetic hydrates in the ocean,non-diagenetic natural gas hydrates produced by solid-state fluidization technology are transferred to a sea surface platform for processing through a controllable process.The traditional static hydrocyclone and other separation equipment have many deficiencies in handling the gas hydrate slurry.The dynamic hydrocyclone is developed on the basis of static hydrocyclone research and has better separation performance.The dynamic hydrocyclone geometric model is used AutoCAD software to establish,the ICEM CFD software is used to divide the grid and simulates the dynamic hydrocyclone flow field in FLUENT.Based on the multiphase flow mixture model,according to the characteristics of strong swirling fluid anisotropy,the Reynolds stress turbulence model(RSM)and the single reference model(SRF)are selected to establish the mathematical model of the dynamic flow field inside the hydrocyclone.The distribution of the flow field in the hydrodynamic cyclone is calculated,including the velocity field,pressure field,density distribution and the distribution of the volume fraction of each phase.At the same time,the law is revealed of the tangential velocity,axial velocity,radial velocity,pressure distribution,density distribution and distribution rule of the volume fraction of each phase,and the influence of the separation efficiency of a dynamic hydrocyclone is obtained.The key structures of the dynamic hydrocyclone,include length-diameter ratio,the length of blades,the number of blades,the diameter of the overflow port.The depth of overflow pipe insertion are studied.The results showed that,with the increase of length-diameter ratio,the separation efficiency will appear obvious trend of increasing first and then decreasing.The increase in the length of the blade and the number of blades,the separation efficiency increases first and then decreases,but the overall change is not significant.With the increase of the overflow diameter,the separation efficiency increases accordingly.The effect of the insertion depth of the overflow tube on the separation efficiency is small.Through the orthogonal test scheme,the primary and secondary relationships of the influence of each structural parameter on the separation efficiency are obtained,overflow port diameter,number of blades,insertion depth of overflow pipe,length of blade and ratio of length to diameter.Based on the above analysis,the structural parameter combination with the highest separation efficiency is optimized.The effects of the five process parameters of the dynamic hydrocyclone on the separation performance of the dynamic hydrocyclone are investigated,including the rotating speed of the rotary hydrocyclone,the diameter of the inlet solid particle,the inlet flow,the volume fraction of the sand and the volume fraction of the natural gas hydrate.The results showed that the higher the rotating speed,the higher the separation efficiency,the diameter of inlet solid particles increases to a certain extent,and the separation efficiency increases accordingly,increased inlet flow,the separation efficiency slightly increases and then decreases,when the volume fraction of the inlet silt increases and reaches a certain value,the separation efficiency drops sharply,the inlet gas hydrate volume fraction increases,and the separation efficiency decreases.