How Particles with Sizes Close to Cut Size Affect the Multiphase Flows and Performance of Hydrocyclones

Abstract

Hydrocyclones classify particles by size but face inefficiency in handling particles with sizes close to the cut size (referred to as cut-size-near particles). This paper presents a numerical study on the cut-size-near particle behavior and its impacts on cyclone performance using a validated two-fluid model. The particle size distribution of interest follows a Johnson’s SB distribution, with a median size of d 0.5 and a spread of σj. The case of d 0.5 close to a reference cut size is focused, where values of σj accord with various fractions of cut-size-near particles. The numerical results show that a larger σj decreases the water split and separation precision while increasing the cut size and pressure drop. Generally, the effect of σj exerting on a larger hydrocyclone is more apparent, even causing a plateau in partition curves. These phenomena are elucidated by the detailed analysis of multiphase flows and forces acting on particles.

Study on the Separation Performance of a Two Cylindrical Section Hydrocyclone under Various Height Ratios

“…Hydrocyclones, which are widely used in various areas, including mineral processing, petrochemicals, environmental protection systems, and biological systems, are used for the separation of nonhomogeneous mixtures via centrifugal sedimentation. − These devices have the advantages of simple structures, nonmovable parts, and low investment costs, among others. In mineral processing, hydrocyclones are mainly used for classification, sorting, designing, and thickening, in addition to other functions. , Within hydrocyclones is the separation behavior of particles under the influence of centrifugal force, gravity, buoyancy, drag, etc., which is a highly developed turbulent movement, the internal hydrodynamic properties and particle movement behaviors are extremely complicated. − Because of their structural limitations, the separation process inevitably involves particle misplacement of overflow and underflow, which is usually characterized by reductions in the recovery yield and quality of the target products. Therefore, alleviating particle misplacement has become a critical issue that is limiting improvements in hydrocyclone separation performance. , …”

“… 5 , 6 Within hydrocyclones is the separation behavior of particles under the influence of centrifugal force, gravity, buoyancy, drag, etc., which is a highly developed turbulent movement, the internal hydrodynamic properties and particle movement behaviors are extremely complicated. 7 − 9 Because of their structural limitations, the separation process inevitably involves particle misplacement of overflow and underflow, which is usually characterized by reductions in the recovery yield and quality of the target products. Therefore, alleviating particle misplacement has become a critical issue that is limiting improvements in hydrocyclone separation performance.…”

Designing the Spigot Structure of Hydrocyclones to Reduce Fine Particle Misplacement in Underflow

“…Hydrocyclones are used as centrifugal separation equipment in petrochemical, mineral separation, sewage treatment, biological, and other applications due to their easy operation, lack of moving parts, and small footprint [1][2][3][4]. Within a hydrocyclone is a nonhomogeneous mixture of centrifugal force, gravity, drag, and other multiple coupled forces under the effect of turbulence; additionally, the internal hydrodynamic properties and particle behavior are highly complex, and it is always difficult to obtain a satisfactory separation effect [5][6][7]. For the sewage treatment process, hydrocyclones can effectively remove the entrained sand in sewage and alleviate the clogging and erosion of the drainage network, but there are problems such as low underflow concentrations with plenty of fine particles in practical application, which affect the subsequent efficiency of sand dewatering and recycling.…”