旋流器对电脱盐装置含油污水的处理

介绍了旋流器在炼油厂电脱盐装置污水处理系统中的工艺流程。经旋流器处理，电脱盐装置排出污水的含油量可稳定降低到150mg/L以下，实现了装置排出污水分级达标管理的目标。     

水力旋流器内固体颗粒的沉降

水力旋流器内固体颗粒的离心沉降是一种复杂的两相流行为。从分析固液体系的相互作用，分别讨论了颗粒的自由沉降、干涉沉降问题，提出了高浓度下水力旋流器内颗粒之间的几种碰撞模式，阐述了旋流器内颗粒沉降的特殊性及其与使流器工作和旋流器结构间的可能联系，并指出了离心沉降本身有待深入研究的若干问题。     

Improvement of hydrocyclone separation performance by incorporating a conical filtering wall

In this work, the performances of conventional hydrocyclones have been compared with a new configuration, known as filtering hydrocyclone. This non-conventional solid–liquid separator consists of a hydrocyclone whose conical section is replaced by a conical filtering wall. Thus, during the operation of these devices, besides the underflow and overflow streams, there is another stream of liquid, resulting from the filtrate produced in the porous cone. The experimental and CFD results, obtained in 25 different configurations of both conventional and filtering hydrocyclones, show that the performance of hydrocyclones is significantly influenced by the replacement of the conical section of the conventional device by a conical filtering wall. The separation performance and the capacity can be enhanced with the filtering hydrocyclones, as compared with similar conventional.     

Effect of feed body geometry on separation performance of hydrocyclone

ABSTRACT

The misplacement of coarse particles in overflow and fine particles in underflow are problems in hydrocyclone separation. This paper proposes improved feed body design of a hydrocyclone and the effect of feed body geometry on the flow field and separation performance is investigated experimentally and theoretically using PIV and CFD, respectively. The air core formation and the velocity field are in good agreement using both approaches. Further simulated results indicate that the tapered feed body causes a reduction in fines entrainment by underflow, suitable for fine particles classification. In contrast, the conical feed body is advantageous for eliminating short circuiting.     

旋流器排口比对固粒轴向流场的影响

通过对ＰＤＡ测得的不同条件下的轴向场的分析，提出了水力旋流器内固相颗料向速度场的新的分析概念。并对测得的数据进行计算机拟合，得出了各区域内颗粒轴向速度的计算公式，为固相颗粒运动轨迹的计算提供了依据。     

A Comparative Study on the Separation of Different‐Shape Particles Using a Mini‐Hydrocyclone

The separation efficiency from water of different‐shape particles was studied experimentally using a mini‐hydrocyclone. Spherical and flaky (plate‐like) aluminum particles with the same particle size distributions were employed. Also, the effects of the feed flow rate and the temperature on the separation performance were studied. The results were investigated in terms of slurry recovery, total efficiency, and partition curves. The separation efficiency of the spherical particles increased with increasing particle size, temperature, and feed flow rate, as expected. The fishhook effect, as a noticeable phenomenon, was observed for the spherical particles. In case of the flaky particles, the separation showed an unusual behavior: The separation efficiency decreased with increasing particle size in the largest particle fraction, which has so far not been reported and addressed in this way.     

Performance characteristics for particles of sand FCC and fly ash in a novel hydrocyclone

With growing industrialization in power sector and petrochemical industries water has been contaminated with particulates like sand, fly ash and FCC. In the present investigation, a new type of hydrocyclone was designed and fabricated. The system is designed in such a manner that it can operate in a wide range of variables for sand, sand-ash and sand-FCC systems. A detailed study on performance analysis of hydrocyclone, pressure drop, cut size particle diameter and particle characterization has been carried out for the design of the hydrocyclone. A mathematical model for predicting particle separation efficiency and cut size particle diameter has been developed. A correlation has been developed for percentage removal of particles and retention of particles in the hydrocyclone. An experimental finding shows 96% removal efficiency for particle with cut size diameter of , which can meet the required separation in industrial application.     

Production of natural graphite particles with high electrical conductivity by grinding in alcoholic vapors

Natural graphite particles with a high crystallinity, which were sieved to obtain particles less than 63 μm, were ground with a ball mill under a dry atmosphere and various alcoholic vapors such as i-C₃H₈OH, n-C₃H₈OH, C₂H₅OH, and CH₃OH. The size and flakiness of the ground products and the electrical conductivity of the films made from the ground products were experimentally examined. Grinding the particles under alcoholic vapors slowly reduced the particle size and was similar to grinding in dry air, but grinding in alcoholic vapors produced flakier products. The graphite films, which were composed of flakier particles and were ground in alcoholic vapor, displayed higher electrical conductivities than the feed graphite particles. The products ground in C₂H₅OH, i-C₃H₇O and n-C₃H₇OH vapors had 50% or less of the specific resistance of the feed particles.     

Mechanism of Particle Separation in Small Hydrocyclone

The mechanism of particle separation in a small hydrocyclone is analyzed in this study. The separation efficiency of particles is affected by two major effects, the centrifugal and underflow effects. The fundamentals of these effects on the selectivity curve are derived from the theories of hydrodynamics. Three JIS particulate samples are separated in a 10-mm hydrocyclone. The proposed mechanism can be demonstrated by the available data. An increase in split ratio leads to an increase in the separation efficiency only for fine particles; consequently, a decrease in the separation sharpness results in a remarkable fishhook phenomenon. When the feed rate is increased by increasing the pressure drop through the hydrocyclone, the entire partial separation efficiency will be improved, but the separation sharpness and fishhook depth have no substantial varieties. The proposed mechanism can be used for explaining these phenomena, for the selection of optimum operating conditions, and for the hydrocyclone design.     

Practical Application of the Probabilistic‐Statistical Model of the Suspension Separation in Hydrocyclones

An effective practical approach that allows not only a significant reduction in the scope of practical experiments in the course of studying suspension separation processes in hydrocyclones, but also makes it possible to assess the intensity of random components of the processes and define the interrelation between such components and hydrodynamics of flows in a hydrocyclone is presented. Within the frames of the developed probabilistic‐statistical model of suspension separation in hydrocyclones on the basis of statistical self‐similarity properties, a relationship was found between determined and random components of the processes. This allowed transitioning from three‐parameter probability density functions for suspension particles in hydrocyclones to two‐parameter functions; thus significantly improving the efficiency of practical application of the developed model.     

Surface structuring of diamond-like carbon films by colloidal lithography with silica sub-micron particles

By combining colloidal lithography and pulsed-DC plasma deposition of diamond-like amorphous carbon films, we have fabricated sub-microstructures that modulate the surface properties of this material. A self-assembled monolayer of silica sub-micron spheres was deposited on monocrystalline silicon, which was patterned either by thermal annealing of the particles or by hole-mask lithography via ion beam etching with argon. The samples showed hemispherical close-packed topographies and micro-pillar networks. The coefficient of friction, measured with a nanotribometer, and the wettability were controlled through this special surface patterning. These structures are suitable for applications requiring protective coatings with large area showing hydrophobic properties.     

Oxidation of cyanide in a hydrocyclone reactor by chlorine dioxide

The greatest amounts of cyanide-containing wastes are produced by precious metals milling operations, the electroplating industry and coal processing or coking effluents processes. Because of high toxicity and to comply with federal and state regulations, the treatment of wastewater is required before safe discharge of cyanide wastes. In this regard, the gas-sparged hydrocyclone (GSH) has been tested as a reactor for the treatment of cyanide solutions for cyanide destruction by oxidation with the use of chlorine dioxide gas (ClO₂). The results show oxidation efficiencies of free cyanide approached 99% at all pH values in 5 min. The use of NaCl was also considered for the generation of chlorine dioxide. Excellent performance appears to offer operational and cost advantages over conventional processes.     

The plasma production of ultrafine silica particles

A process for producing ultrafine silica particles incorporating a plasma transferred-arc reactor of novel design (Plas-macan) was developed. The process consisted of vapourizing small particles of sand (99.5% SiO₂) which subsequently dissociated into SiO gas and oxygen in the presence of an argon plasma. Quenching of this gaseous mixture reconstituted SiO₂ in the form of an aerosol. Various reacting media (H₂, steam or NH₃) were tested to assist the dissociation and to enhance the properties of the particles produced. The quenching of the particles was effected with oxygen or steam. A feedrate of 1.3 kg/h SiO₂ and a power of 30 kW for plasma generation were used throughout the work. Amorphous silica particles, average 0.07 μm in diameter, were produced.     

用于细颗粒分离的水力旋流器的压力特性研究

对用于细颗粒分离的水力旋流器的压力特性 (压力降及压降比 )与流量、分流比、旋数、溢流口和底流口直径及气液比等主要参数之间的关系进行了深入的研究与分析。研究发现 ,水力旋流器内部压力降分别随流量、分流比、旋数及气液比的提高而加大 ,压降比则分别随流量、分流比、旋数的提高而降低。随着溢流口直径的加大 ,水力旋流器的溢流压力降减小 ,而压降比也随之降低 ;随着底流口直径的加大 ,底流压力降减小 ,压降比随之升高。分析可知 ,减少旋流器能耗的有效方法是降低旋数 ,或者减少混合介质中的气液比     

Solid dispersion particles of tolbutamide prepared with fine silica particles by the spray-drying method

Solid dispersion particles of tolbutamide (TBM) were prepared by formulating nonporous (Aerosil 200 (hydrophilic), Aerosil R972 (hydrophobic)) or porous (Sylysia 350 (hydrophilic), Sylophobic 200 (hydrophobic)) silica as a carrier and applying the spray-drying (SD) or evaporation (Eva) method. In the solid dispersion particles prepared by the SD method, TBM existed in a meta-stable form (Form II) irrespective of the type of silica. On the other hand, when the Eva method was used, various crystalline forms of TBM were observed in the solid dispersion particles according to the type of silica. Polymorphs of Forms III and IV were prepared with Aerosil 200 and Aerosil R972, respectively, while crystalline Form II was obtained when either of the forms of porous silica, Sylysia 350 or Sylophobic 200, was formulated. The dissolution property of TBM in the solid dispersion particles prepared with hydrophilic silica was remarkably improved compared with those of the original TBM crystals (Form I) or spray-dried TBM without silica (Form II). In the case of hydrophobic silica, the release rate of TBM from the solid dispersion particles was much slower than that of original TBM. The meta-stable form of TBM in the solid dispersion particles was stable for at least 4 weeks when stored at 60 °C and 0% RH, while the spray-dried TBM without silica (Form II) was gradually converted to the stable form (Form I) under the same storage conditions. Under the humid storage conditions (60 °C, 75% RH), the spray-dried TBM without silica (Form II) immediately converted into the stable form (Form I) within 1 day, while TBM (Form II) in the solid dispersions in a matrix of silica was stable for at least 1 week.     

Production of finely ground natural graphite particles with high electrical conductivity by controlling the grinding atmosphere

Natural graphite particles with high crystallinity sieved to obtain a particle size range of under 63 μm were ground with a ball mill, under various well-controlled grinding atmospheres such as N₂, O₂, He, H₂, and vacuum. The ratio, X_dif50/X_st50, i.e. between the 50 wt.% Stokes diameter and the 50 wt.% laser diffraction diameter, of the ground particles, was used as an index of the flakiness of the particles. The specific resistance of films composed of the ground graphite particles was systematically measured. The rate of reduction in the size of the particles by grinding was slow under an O₂-rich atmosphere such as 100% O₂ and dry air. On the other hand, it was relatively fast in vacuum, or under an N₂ or He atmosphere, and a gas mixture of 99% N₂ and 1% O₂. The rate of size reduction by grinding under a H₂ atmosphere was intermediate. In our experimental conditions, the flakiness of the ground particles increased with the decrease in the particles’ sizes. The electrical conductivity of the ground particles, however, tended to decrease with the decrease in their sizes. Under the condition that the Stokes diameter of the ground particles remains constant, the electrical conductivity of films made from the ground particles increases with the increase in the flakiness of the particles. It was finally determined from our systematic grinding experiments that small flaky particles, which had a size, X_st of ∼1 μm, with a high electrical conductivity can be produced by grinding in a gas mixture of 99% N₂ and 1% O₂. In this case, the flaky shape of the ground particles was visually confirmed by scanning electron microscopy.     

Characterization of spherical silica–titania mixed oxide particles synthesized by using a dry process

Silica–titania mixed oxides have excellent properties, such as a low thermal expansion coefficient and a refractive index that can be adjusted by changing the Ti content. However, when the Ti content increases, silica and titania phases in silica–titania mixed oxides can separate. This phase separation leads to the precipitation of the titania component as rutile or anatase crystals. When silica–titania mixed oxides undergo phase separation, their properties become unstable; for example, the refractive index of the particles becomes non-uniform. Therefore, it is preferable to synthesize silica–titania mixed oxides in an amorphous state without causing phase separation. Based on our previous studies on particle size control in silica synthesis, we employed a dry process using organosilicon compounds to synthesize silica–titania mixed oxides. In this study, spherical amorphous silica–titania mixed oxide particles were obtained via flame synthesis using organosilicon and organotitanium compounds. The purpose of this study was to characterize the obtained powder and explore the possibility of controlling particle size during synthesis. By studying the dry process synthesis of spherical silica–titania mixed oxide particles, we confirmed the relationships: between the Si/Ti molar ratio and the obtained crystal structure and between the adiabatic flame temperature and the particle size.     

Design and performance evaluation of hydrocyclones for removing micron particles suspended in water

A hydrocyclone for collecting micron-sized hydrosols efficiently has been studied through experimentation. Hydrocyclones separate particles of the dispersed phase from the liquid on the basis of the density difference between the phases. The purpose of this study was to design and evaluate the performance of a high-capacity hydrocyclone for the removal of submicron-sized particles suspended in liquid. Furthermore, the performance of three types of hydrocyclone was evaluated with regard to solid particle density using fly ash and coagulation sludge. The particle cut-size decreases with reducing inlet area and increasing inlet velocity in the hydrocyclone. The hydrocyclones have good performance, which is demonstrated by the optimal cut-size of 20 μm in mass median diameter at the inlet diameter per body diameter ratio of 0.21 and the pressure drop of 72.5 kPa with a particle density of 2,500 kg/m³.     

Studies on the performance of a hydrocyclone and modeling for flow characterization in presence and absence of air core

Hydrocyclones are getting more and more interest from various industries. They are widely used to separate particulates from liquid at high throughput because of their advantages like simple structure, low cost, large capacity and small volume, require little way of maintenance and support structure. Modeling of complex and multiphase flow behavior inside the hydrocyclone is done usually with the help of computational fluid dynamic study. Current study involves experimental investigation of separation performance characteristics of the hydrocyclone using new design parameters. For experimental purpose, a new hydrocyclone was designed with insertion of solid rod, at central portion of conical section of hydrocyclone, inside the hydrocyclone . By which air core could be eliminated effectively and hydrocyclone performance is improved. This effect may be observed due to reduction of radial and axial components of velocity and turbulence in the area near the entrance of the vortex finder. Therefore, the flow field characteristics inside the hydrocyclone with no air core become more suitable for separation. Also the effect of flow rate, vortex finder depths, air core and particle interaction were studied experimentally. A new arrangement was suggested to eliminate the air core formed inside the hydrocyclone. In this case, effect of diameter and height of solid rod inserted inside the hydrocyclone with changing total inlet flow rate was studied experimentally. Three-dimensional geometry and meshing of hydrocyclone is created in Gambit, preprocessor of commercial software—Fluent, for hydrodynamic study.     

Adhesion interaction in water/n-alcohol mixtures between silanized silica and polymer particles

The adhesion of polyethylene and nylon particles to silanized silica plates was investigated in water/n-alcohol (methanol, ethanol, 1-propanol, and 1-butanol) mixtures. Silica plates were treated with γ-aminopropyltriethoxysilane, methyltriethoxysilane, and perfluoroethyltrimethoxysilane. The number of particles adhering to the plate at 60 min as an apparent equilibrium adhesion value increased as a result of the silanization of silica and decreased with increasing volume ratio of n-alcohol in the water/n-alcohol mixtures. The acid-base components of the surface free energies of the substrates and liquids were decreased by the silanization of silica and by the addition of cthanol to water. The apparent equilibrium particle adhesion is discussed in terms of the total potential energies of interaction which were calculated as the sum of the electrical double layer, Lifshitz-van der Waals, and acid-base interactions, using the electrokinetic potentials and the surface free energy components. In addition, the relationship between the extent of particle adhesion and the work of adhesion was investigated. The particle adhesion in the present systems was found to be dominated by the acid-base interaction between the particle and the substrate.