Numerical Simulation of Fluid Flow and Oil-Water Separation in Hydrocyclones

The fluid flow and oil-water separation were simulated using a Reynolds stress transport equation model of turbulence in water flow and a stochastic model of oil droplet motion. Simulation results give the axial and tangential velocity components, the pressure and turbulence intensity distribution and droplet trajectories for a hydrocyclone of F type and a hydrocyclone proposed by the present authors. The flow field predictions are in qualitative agreement with the LDV measurements. The results show that the proposed hydrocyclone has better performance than the hydrocyclone of F type due to creating stronger centrifugal force and lower axial velocity.

Characterization of Flame Retardancy and Oil-Water Separation Capacity of Superhydrophobic Silylated Melamine Sponges

A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourier-transform infrared)spectroscopy,SEM(Scanning electron microscopy)and in terms of water contact angles.Its oil-water absorption and separation capacities were measured by FT-IR and UV-visible spectrophoto-metry.The experimental results have shown that oligomeric silanol covalently bonds by Si-N onto the surface of melamine sponge skeletons.SMS has shown superhydrophobicity with a water contact angle exceeding 150°±1°,a better separation efficiency with regard to diesel oil(by 99.31%(wt/wt%)in oil-water mixture and even up to 99.99%(wt/wt%)for diesel oil in its saturated aqueous solution.Moreover,SMS inherited the intrinsicflame retardancy of the melamine sponge.In general,SMS has shown superhydrophobicity,high porosity,excellent selectivity,remarkable recyclability,and better absorption capacity for various oils and organic solvents,and a high separation efficiency for oil in saturated aqueous solutions.

Development of separation sharpness model for hydrocyclone

Hydrocyclones are mechanical devices used in classifying and separating many different types of materials.A classification function of the hydrocyclone has been continually developed for solid–liquid separation.In the classification process of solids from liquids,it is desirable to reduce the amount of misplaced material;therefore,the separation sharpness,α(alpha),is a parameter that helps in evaluating misplaced material and has been developed as a model to help the designer predict the performance of the classification.However,the problem with the separation sharpness model is that it cannot be used outside the range of conditions under which it was developed.Therefore,this research aimed to develop the separation sharpness model to predict more accurately and cover a wide range of conditions using the multiple linear regression method.The new regression model of separation sharpness was based on a wide range of both experimental and industrial data-sets of 431 tests collaborating with the additional experiments of 117 tests that were obtained from a total of 548 tests.The new model of separation sharpness can be used in the range of 30–762 mm hydrocyclone body diameters and feed solid concentrations in the range of 0.5 wt%–80 wt%.When compared with the experimental separation sharpness,the accuracy of the separation sharpness model prediction has an error of 4.53%and^of 0.973.

Oil–water pre-separation with a novel axial hydrocyclone

A novel hydrocyclone with guide vanes, named as axial hydrocyclone(AHC), is designed to tackle the problem of oil–water separation faced by most mature oilfields. Optimal design of the AHC is carried out by using numerical methods. The effects of guide vanes, cone angle, tapered angle and overflow pipe on the oil–water separation are discussed in this paper. The results show that a double swirling flow is generated in the tapered section where oil–water separation occurs. Both the cylindrical and the tapered section have important influences on AHC performance. On the basis of single factor results, response surface methodology is employed to optimize the AHC design. The experimental results indicate that the novel AHC has an excellent performance for the oil–water separation.

Robust,fluorine-free and superhydrophobic composite melamine sponge modified with dual silanized SiO_(2) microspheres for oil-water separation

Massive oily wastewater discharged from industrial production and human daily life have been an urgent environmental and ecological challenge.Superhydrophobic materials have attracted tremendous attention due to their unique properties and potential applications in the treatment of wastewater.In this study,a novel superhydrophobic/superoleophilic composite melamine sponge modified with dual silanized SiO_(2) microspheres was fabricated simply by a two-step sol-gel method using vinyltriethoxysilane and hexadecyltrimethoxysilane as functional agent,which exhibited a water contact angle of 153.2°and a water sliding contact angle of 4.8°.Furthermore,the composite sponge showed the excellent oil adsorption performance and the compressive elasticity reaching up to 130 g·g^(-1) of dichloromethane and 33.1 kPa of compressive stress.It was worth noting that the composite sponge presented the excellent separation efficiency(up to 99.5%)in the processes of continuous oil/water separation.The robust superhydrophobic composite melamine sponge provided the possibility with the practical application for oil-water separation.

Pressure characteristics of a hydrocyclone for fine particle separation

Solid-liquid hydrocyclones are mainly used to separate large particles, such as the particles of drilling fluid in petroleum industry, and large mineral particles. Till now the hydrocyclonic separation for fine particles is still a big problem. Basic separation principle of hydrocyclones and experimental research facility are simply introduced. The difficulty of separating fine particle is analyzed. Based on a solid-liquid hydrocyclone used for separating fine particles, relationships of dimensionless pressure characteristic parameters, i.e. Euler number and pressure drop ratio, with several main dimensionless parameters, such as split ratio, swirl number and gas-liquid ratio, were experimentally studied in detail. The research was carried out by using the hydrocyclonic separation experimental rig at the University of Bradford. It is shown that the less the size of particle, the less the value of radius of the balance orbit occupied by the particle, and then the more difficult for the particle to be separated. Experiments indicate that Euler number of the tested hydrocyclone increases with the rise of Reynolds number, split ratio, swirl number and gas-liquid ratio respectively, and the pressure drop ratio falls with the increase of Reynolds number, split ratio and swirl number respectively. It is concluded that the most effective way to decrease the unit energy dissipation of hydrocyclone is to reduce swirl number or gas-liquid ratio of the mixed media.

Simultaneously spray-assisted assembling reversible superwetting coatings for oil-water separation

Here,superhydrophobic cuprous oxide(Cu2O)with hierarchical micro/nanosized structures was synthesized via sprayassisted layer by layer assembling.The asprepared superhydrophobic meshes with high contact angle(159.6°)and low sliding angle(1°)are covered with Cu_(2)O "coral reef"like micro/nanosized structures.Interestingly,the superhydrophobic mesh surfaces became superhydrophilic again due to the oxidization of Cu_(2)O to CuO by annealing at a higher temperature(300℃).And the superhydrophobic properties would be recovered by heating at 120℃.Furthermore,the superwetting meshes were applied to design a miniature device to separate light or heavy oil from the wateroil mixtures with excellent separation efficiency.These superwetting surfaces by simultaneously sprayassisted layer by layer assembling technique show the potential application in universal oilwater separation.

Effect of Stirring on Oil-Water Separation in Rare Earth Mixer-Settler

Oil-water separation is critical to solvent extraction process of rare earth, which can directly affect the yield and quality of the product. The experiments measure the two-phase separation time in a beaker, mixing uniformity of two phases in the mixer and the oil phase entrainment at oil exit by the Karl Fischer method and numerical simulation for the mixersettler to study the combined effect of gravity and stirring. Experimental results show that relative to the static situation, the separation efficiency resulted from low-speed stirring is increased by 25%. The water content in the oil is a minimum at an offset distance L of 10 cm and the clearance off the tank bottom z of 10 cm is as low as 0.49%. Distribution images of oilwater separation at 2 s indicates that stirring is very conducive to the separation of the oil-water phase.

Magnetic Wood-based Superhydrophobic Aerogel for Efficient Oil-Water Separation

The fabrication of directionally driven oil-water separation materials has great significance for the removal of oil spills and organic pollutants.In this study,an oil-water separation aerogel capable of directionally adsorbing oil was designed using an anisotropic wood aerogel with a layered structure and a top-down fabrication strategy.Specifically,a magnetic wood-based superhydrophobic aerogel(methyltrimethoxysilane(MTMS)/Fe_(3)O_(4) wood aerogel)was developed through the in situ coprecipitation of Fe_(3)O_(4) nanoparticles and chemical vapor deposition.Owing to its highly porous structure,lipophilicity,hydrophobicity(water contact angle of 160°),and high compressibility,the MTMS/Fe_(3)O_(4) wood aerogel exhibits excellent oil-water separation performance and compression cycle stability.Additionally,the Fe_(3)O_(4) endows the material with excellent magnetic and photothermal conversion capabilities.These excellent properties make MTMS/Fe_(3)O_(4) wood aerogel a promising recyclable and sustainable oil-water separation material.

Preparation of Silica Nanosphere with Vertical Pore and Its Application in Oil-water Separation

Uniform monodispersed mesoporous silica nanospheres with vertical pores were successfully synthesized using chiral amphiphilic small molecule L-16Ala5PyClO4and solvents as dual templates via solgel transcription.The morphologies and pore sizes of silicas are adjustable by changing the type and amount of solvents in the reaction systems.With the increase of the organic solvent content,the morphologies of the obtained silica changed from nanospheres with vertical pore structures to nanosheets structures.When 1 mL of benzene,cyclohexane or toluene were used as solvents,only silica nanospheres were obtained,the BET surface areas of silica nanospheres reached 600.7,669.5,and 560.8 m^(2)/g,respectively.The pore sizes were 3.51,3.54,and 3.46 nm,respectively.Significantly,these ordered silica nanospheres/poly(vinyl alcohol-co-ethylene)(PVAco-PE)nanofiber membranes have high separation efficiencies(>99%)for n-hexane/water mixtures.

Electrospinning Nanofiber Membrane Reinforced PVA Composite Hydrogel with Preferable Mechanical Performance for Oil-Water Separation

Nowadays hydrogels have been attracting the massive interest in oil-water separation due to their robust hydrophilicity and fantastic underwater oiliness features.However,the weak toughness and tensile strength shortcomings of hydrogels have thus inhibited their actual applicability.For this reason,we successfully fabricated the electrospun nanofiber membrane-reinforced PVA composite hydrogels.The PVA-PAN composite hydrogel has exhibited the excellent tensile strength and friction performance,separately enhancing 174.2%of the tensile strength,and reducing 20.7%of the friction coefficient and 58.7%of wear volume relative to the neat PVA hydrogel.Furthermore,the pull-out experiments indicated that the PAN nanofiber membrane exerted a stronger interface bonding effect with PVA hydrogel.The oil-water separation evaluation test showed that the separation efficiency reached up to 97.6%for treating the SA-100 lubricating oil/water system.

Preparation of Hydrophobic Fly Ash by Surface Modification and Oil-water Separation Devices

A simple and effective superhydrophobic mesh was designed and made to separate oil-water mixture. Alkali-activated fly ash reacted with 1-bromooctadecane to prepare superhydrophobic modified fly ash (MFA) with low surface energy through Williamson ether synthesis. The MFA powder was then coated uniformly on a stainless steel mesh (SSM) along with the epoxy resin E44 and curing agent T31 to give the superhydrophobic MFA-modified stainless steel mesh (MFA-SSM). The MFA-SSM has a high static water contact angle (CA) of 150.1°and can separate various oil or organic solvent from water with>95%separation efficiency. The oil-water separation efficiency remained high after 30 runs of petroleum ether/water separation.The developed superhydrophobic stainless steel mesh is expected to have wider use in oil-water separation.

Non-Isothermal Separation Process of Two-Phase Mixture Water/Ultra-Viscous Heavy Oil by Hydrocyclone

Environmental agencies do not allow effluents, from the petroleum productions, which contain oil concentrations that exceed the amounts permitted by the regulations. In recent time heavy oil operating petroleum industries are generating oil/water mixture by products, which are difficult to separate. Industrially, hydrocyclone is generally used to separate oil from an oil/water mixture. This is due to its high performance of separation, low cost of installation and maintenance. In the present work, therefore, the thermal fluid dynamics of water/ultra-viscous heavy oil separation process in a hydrocyclone has been studied. A steady state mathematical model which simulates the performance of a non-isothermal separation process is presented. The Eulerian-Eulerian approach for the interface of the phases involved (water/ultra-viscous heavy-oil) is used and the two-phase flow is considered as incompressible, viscous and turbulent. For carrying out numerical solutions of the governing equations the CFX11? commercial code was used. Results of the behavior of the two-fluid flow inside the hydrocyclone and separation efficiency are presented and analyzed. The role of the average temperature of the fluid, oil droplet diameter and the fluid mixture inlet velocity on the separation efficiency of the hydrocyclone are verified.

NIR-responsive Collagen-based Sponge Coated with Polydimethylsiloxane/Candle Soot for Oil-Water Separation

To fabricate an oil-water separation material that is rich in source,eco-friendly,and responsive,in this study,we successfully developed a collagen-based sponge for application to oil-water separation based on a green and facile strategy.In this design,widely-available collagen(COL)was used as the substrate:it was immersed in polydimethylsiloxane(PDMS)suspension with candle soot(CS)nanoparticles,followed by hot curing.The resultant sponge(CS/PDMS-COL)possessed good hydrophobicity with a water contact angle of 148.3°under a low PDMS concentration of 2%.The results from field emission scanning electron microscope,Fourier transform infrared spectrometer,X-ray photoelectron spectrometer,and X-ray diffractometry demonstrated the successful coating of CS and PDMS on the surface of COL substrate.The CS/PDMS-COL can adsorb eight oils,with the adsorption capacity for trichloromethane reaching 95 g/g.With benzene as the target adsorbent,the separation efficiency was maintained at no less than 95%even after recycling 20 times.CS/PDMS-COL was also used to separate oil-in-water emulsion.Moreover,the sponge killed bacteria effectively due to its excellent near-infrared photothermal responsiveness.This study provides new insight into the preparation of facile oil-water separation materials based on naturally occurring biomaterials effortlessly.

Testing of separating catalyst from resid fluid catalytic cracking slurry by 10 mm hydrocyclones

The paper focuses on removing catalyst solids from oil slurry using 10 mm hydrocyclones, and aims to test the feasibility of the solution. An industrial sidetrack tester of residual oil separation by hydrocyclones was set up in 1.8 Mt/a resid fluid catalytic cracking （RFCC） unit, the effect of pressure drop, separation efficiency and inlet flowrate were studied. It was observed that an increase in feed flowrate will decrease the pressure drop ratio, and with an increase in feed flowrate, separation efficiency increases gradually. Under the condition that feed fiowrate was ranging from 250L/h to 270L/h, the separation efficiency was 45.77%-82.80%, the recovery rate of catalyst solid panicles was increased from 10 20% of electrostatic catalyst separator to 50 80%. Thus, it is feasible to separate the slurry by using the miniature hydrocyclones in RFCC unit.

CFD numerical simulation of flow velocity characteristics of hydrocyclone

A CFD based numerical simulation of flow velocity of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The results show there exist several unsymmetrical envelopes of equal vertical velocities in both upward inner flows and downward outer flows in the hydrocyclone, and the cone angle and apex diameter have remarkable influence on the vertical location of the cone bottom of the envelope of zero vertical velocity. It is also found that the tangential velocity isolines exist in the horizontal planes located in the effective separation region of hydrocyclone. The increase of feed pressure has almost no effect on the distribution characteristics of both vertical velocity and tangential velocity in hydrocyclone, but the magnitude and gradient of tangential velocity are increased obviously to make the motion velocity of high density particles to the wall increased and to make the cyclonic separation effect improved.

Numerical analysis of hydroabrasion in a hydrocyclone

The velocity profiles and separation efficiency curves of a hydrocyclone were predicted by an Euler-Euler approach using a computational fluid dynamics tool ANSYS-CFX 14.5. The Euler-Euler approach is capable of considering the particle-particle interactions and is appropriate for highly laden liquid-solid mixtures. Pre- dicted results were compared and validated with experi- mental results and showed a considerably good agreement. An increase in the particle cut size with increasing solid concentration of the inlet mixture flow was observed and discussed. In addition to this, the erosion on hydrocyclone walls constructed from stainless steel 410, eroded by sand particles （mainly SiOz）, was predicted with the Euler-La- grange approach. In this approach, the abrasive solid particles were traced in a Lagrangian reference frame as discrete particles. The increases in the input flow velocity, solid concentration, and the particle size have increased the erosion at the upper part of the cylindrical body of the hydrocyclone, where the tangential inlet flow enters the hydrocyclone. The erosion density in the area between the cylindrical to conical body area, in comparison to other parts of the hydrocyclone, also increased considerably. Moreover, it was observed that an increase in the particle shape factor from 0.1 to 1.0 leads to a decrease of almost 70 % in the average erosion density of the hydrocyclone wall surfaces.

Effect of inlet configuration on hydrocyclone performance

Inlet configuration is important parameter of hydrocyclones,which has great impact on the classification performance.The effects of inlet configuration on the precise classification were studied by computational fluid dynamics under variouscombinations of inlet diameter and inlet velocity.The results showed that a high sharpness of classification was achieved withspecific inlet diameter and inlet velocity.The separation efficiency of the coarse particles by underflow significantly decreased wheninlet had an oversize diameter owing to a stronger short-circuit flow.It is resulted from the chaotic flow and the stronger pressuregradient around the vortex finder.Meanwhile,a low separation efficiency of the fine particles by overflow was achieved when inletvelocity was high,which indicated a low sharpness caused by the overlarge centrifugal force.

Study of Structural Parameters of the Inlet of Downhole Hydrocyclones

Three different inlets of hydrocyclone are studied in combination with the construction of a dowrahole system and hydrocyclone. By comparing the relationship between the inlet structure ＆ dimensional parameter of hydrocyclone and separation efficiency ＆ pressure loss, the highest efficiency is obtained from the inlet of an involute curve with increasing depth-width ratio from the three types, in which the separation efficiency and pressure loss all drops slowly, for the length of the channel decreases, while it drops rapidly in the other two. The flow guiding ability of the inlet affects the separation efficiency greatly, so the corresponding involute type of inlet of hydrocyclone fits for downhole oil-water separation is optimized, which serves as a basis for the structural design of downhole hydrocyclone.

Influences of top clearance and liquid throughput on the performances of an external loop airlift slurry reactor integrated mixing and separation

A new developed external loop airlift slurry reactor, which was integrated with gas–liquid–solid three-phase mixing, mass transfer, and liquid–solid separation simultaneously, was deemed to be a promising slurry reactor due to its prominent advantages such as achieving continuous separation of clear liquid from slurry and cyclic utilization of solid particles without any extra energy, energy-saving, and intrinsic safety design. The principal operating parameters, including gas separator volume, handling capacity, and superficial gas velocity, are systematically investigated here to promote the capabilities of mixing, mass transfer, and yield in the pilot external loop airlift slurry reactor. The influences of top clearance and throughput of the clear liquid on flow regime and gas holdup in the riser, liquid circulating velocity, and volumetric mass transfer coefficient with a typical high solid holdup and free of particles are examined experimentally. It was found that increasing the gas separator volume could promote the liquid circulating velocity by about 14.0% at most. Increasing the handling capacity of the clear liquid from 0.9 m3·h-1 to 3.0 m3·h-1 not only could increase the output without any adverse consequences, but also could enhance the liquid circulating velocity as much as 97.3%. Typical operating conditions investigated here can provide some necessary data and guidelines for this new external loop airlift slurry reactor to upgrade its performances.