Properties Of Solid Particles Research Articles

Catalytic oxidation of crotonaldehyde to crotonic acid in a gas-liquid-solid mini-fluidized bed

Oxidation of crotonaldehyde to crotonic acid is an important chemical reaction process because crotonic acid, its derivative and copolymer are ubiquitous in the productions of chemical, cosmetic, and medicines. However, the reactor safety and process efficiency are still not satisfactory. In order to solve such problems, a novel reactor of gas-liquid-solid mini-fluidized bed with bed inner diameter of 3 mm was developed to carry out the selective catalytic oxidation reaction. The effects of operation conditions and solid particle properties on the conversion rate of reactant crotonaldehyde and the selectivity of product crotonic acid were investigated. The causes of these effects are explained from the standpoint of residence time and gas-liquid mass transfer flux. Moreover, the comparison of reactor performance between the three-phase mini-fluidized bed and the batch stirred tank reactor as a traditional one was made to evaluate the performance of such a reactor. Experimental results show that the average reaction or conversion rate of the mini-fluidized bed is about 30 times much higher than that of batch stirred tank reactor to evaluate the improved performance. But the selectivity is less affected by the operation conditions and solid particle bed properties. The size reduction of three-phase mini-fluidized bed decreases the mass transfer distance of molecular diffusion, and the solid particles and mini-bubbles not only provide the higher specific interface area but also cause hydrodynamics changes that is to intensify the interface disturbance, which effectively accelerate the mass transfer.

General approach to describing the properties of solid particles defined by the surface energy

General approach to describing the properties of solid particles defined by the surface energy

Axial meso-scale modeling of gas-liquid-solid fluidized beds

The meso-scale theory, based on the energy minimization multi-scale principle, has recently inspired the accurate modeling of the multi-phase flow. In this study, an axial meso-scale flow model for the gas-liquid-solid fluidized bed is established and verified by the literature models and data. Compared with the reported axial models, this model predicts the axial distribution of all three-phase hydrodynamic parameters with fewer empirical corrections. Predictions of the present model show that the operation conditions and physical properties of solid particles obviously affect the flow behaviors of phases, such as the slip velocity, entrainment of solid particles, wake shedding parameters. Solid particles entrained by bubble wake determine the formation of axial distribution in the gas-liquid-solid fluidized bed. Region with the axial structure is the transition section, length of which depends on the entrainment of solid particles. Furthermore, behaviors of the gas bubbles and the solid particles are mutually influential.

Slurry Water Regeneration after Hydraulic Mining

Treatment and clarification of coal-day suspensions involve of whole range of technological processes, the efficiency of which depends significantly on the concentration of finely dispersed coal in the water-coal suspension. The behavior of flocculation of coal and clay suspensions with high molecular weight substances making possible to forecast the efficiency of polymer action while controlling the electrokinetic properties and aggregate stability of disperse systems has been studied. Aggregation of fine dispersal particles leads to the acceleration of their sedimentation and intensifies technological processes. The flocculant’s efficiency depends on the molecular weight of a polymer and its structure, the charge value of its functional groups, and also the properties of solid particles’ surfaces, methods of solution preparations etc. These factors must provide strong adsorption during the creation of aggregates and provide a significant influence on the flocculant consumption

Gas Sparger Orifice Sizes and Solid Particle Characteristics in a Bubble Column – Relative Effect on Hydrodynamics and Mass Transfer

AbstractThe relative effects of the size of gas sparger orifices and properties of solid particles on gas‐liquid mass transfer are not yet fully understood. Here, the impact of sparger orifice sizes, solid particle shapes, and their loading amounts in a bubble column reactor on the absorption of oxygen in tap water was investigated. Their influence on the mass transfer coefficient and bubble hydrodynamic parameters was evaluated. The results show that the addition of solid particles can have both positive and negative effects on hydrodynamics and mass transfer, depending on the orifice size of the gas sparger. The introduction of ring‐shaped solid particles can improve the mass transfer rate by up to 28 % without requiring any significant additional power.

Combinatorial Particle Patterning

AbstractThe unique properties of solid particles make them a promising element of micro‐ and nanostructure technologies. Solid particles can be used as building blocks for micro and nanostructures, carriers of monomers, or catalysts. The possibility of patterning different kinds of particles on the same substrate opens the pathway for novel combinatorial designs and novel technologies. One of the examples of such technologies is the synthesis of peptide arrays with amino acid particles. This review examines the known methods of combinatorial particle patterning via static electrical and magnetic fields, laser radiation, patterning by synthesis, and particle patterning via chemically modified or microstructured surfaces.

Coupled Effects between Solid Particles and Gas Velocities on Erosion of Elbows in Natural Gas Pipelines

The damage of materials caused by erosion of solid particles occurs on a large scale in different fields, including machinery, aviation, and pipeline transportation, resulting in considerable economic losses in the world. Therefore, the erosion of elbows has been extensively researched, with emphasis on single factors such as properties of solid particles, gas velocities, incidence angles, and temperatures. Erosion is generally affected by two or more coupled factors, however very few studies have been conducted on this subject. Thus, this study investigates the coupled effect between solid particles and gas velocities on the erosion of elbows in natural gas pipelines. A simulation was performed by combining the theoretical model of erosion and the Lagrange discrete phase model. The simulation result was then compared with the results of the working conditions and test platform based on a similar principle. Moreover, the properties of solid particles and the speed of natural gas in pipelines were coupled to analyze the change of erosion rate at different velocities and properties of solid particles (i.e., sizes, shapes, quantities, and incidence angles). Results showed that the erosion rate increases with the increase in size and quantity of solid particles. The small shape coefficient of solid particles causes severe erosion, and their incidence angle influences the rate and position of erosion of the elbows. A complicated coupling effect between solid particles and gas velocities on the erosion of elbows in natural gas pipelines occurs.

Velocity characterization of dense phase pneumatically conveyed solid particles in horizontal pipeline through an integrated electrostatic sensor

Dense phase pneumatic conveying of pulverized fuel particles under high pressure is one of the key techniques in large scale gasification of coal and petroleum coke. The real time and continuous measurement of dense phase gas–solid flow parameters such as particle velocity, concentration and mass flow rate has great significance for the in-depth understanding of particle flow dynamic behaviors and the optimized design of the conveying system. In this paper, an integrated electrostatic sensor is designed and used to explore the flow characteristics of anthracite and petroleum coke particles on a dense phase pneumatic conveyor. The ring electrodes in the integrated sensor are capable of measuring the “mean” velocity of solid particles over the whole cross-section of the pipeline, while the arc electrodes are employed to determine the local velocity of particles near them. The experimental results on a dense phase pneumatic conveyor under high pressure demonstrate that the flow characteristics depend on the physical properties of solid particles and carrying gas. Petroleum coke particles are much easier to be suspended in the gas flow than the anthracite particles, but its flow stability is worse. The local velocities from the arc electrode pairs mounted on the top of the pipeline are usually higher than those from the arc electrodes on the bottom for a stratified flow. The velocity from the ring electrode pair, indicating the mean velocity of particles over the whole cross-section, is usually higher than the local velocities from the arc electrode pairs for a suspension flow. In addition, the relationship between the mass flow rate and charge level of dense phase pneumatically conveyed solid particles is very complicated due to the complexity of the particle flow and the charge level cannot be used to measure particle concentration or mass flow rate.

Characterization of Glass Beads Surface Modified with Ionic Surfactants

Knowledge of the wetting characteristic of mineral surfaces is very important in enhancing the efficiency of separation of valuable minerals from gangue using froth flotation or oil agglomeration. In this paper a capillary rise technique was used to characterize the glass beads surface modified with cationic surfactant. The glass microspheres were used as model particles with a spherical shape and smooth surface to eliminate the roughness effect. The value of the contact angle for water was found to be 21.5 for unmodified beads, and 61.8, 89.7, 68.4 for 0.1, 1.0, 10 mg/gsolid of CTAB, and 39.8, 68.6, 87.9 for 0.1, 1.0, 10 mg/gsolid of DDAHCl, respectively. Data revealed that the adsorption of surfactant onto glass beads decreased the value of the electron donor component, γ-, which defines the hydrophobicity of the surface. Also, the property of the surface was investigated by flotation and oil agglomeration experiments. It was observed that particles with low value of contact angle for water and high for 1-bromonaphthalene and low value of γ- were floated with a recovery equal to 91.1 and 83.1% for CTAB and DDAHCl, respectively, and effectively agglomerated. This indicates that the capillary rise method can be successfully used to predict the wetting properties of solid particles in mineral processing.

Co-sorption of ofloxacin and Cu(II) in soils before and after organic matter removal

Various mechanisms play roles simultaneously for antibiotic sorption on solid particles. Previous studies simply emphasized mechanisms that match the increased or decreased antibiotic sorption by metal ions, without a general concept including these diverse mechanisms in their co-sorption. We observed both increased and decreased OFL and Cu(II) sorption in their co-sorption system. The comparison of the sorption coefficients of primary adsorbate (Kdpri) and co-adsorbate (Kdco) suggested that enhanced sorption occurred at high Kdpri region (low primary adsorbate concentration). Competitive sorption was observed when Kdpri was decreased to a certain value depending on solid particle properties. We thus summarized that if the adsorbates were introduced with low concentrations, OFL (such as hydrophobic region in solid particles) and Cu(II) (such as inner-sphere complexation sites) occupied their unique high-energy sorption sites. Cu(II) complexed with the adsorbed OFL, and OFL bridged by the adsorbed Cu(II) promoted the sorption for both chemicals. With the increased concentrations, the adsorbates spread to some common sorption sites with low sorption energy, such as cation exchange and electrostatic attraction region. The overlapping of Cu(II) and OFL on these sorption sites resulted in competitive sorption at high concentrations. The previously reported apparently increased or decreased sorption in antibiotic–metal ion co-sorption system may be only a part of the whole picture. Extended study on the turning point of decreased and increased sorption relating to water chemistry conditions and solid particle properties will provide more useful information to predict antibiotic–metal ion co-sorption.

Effects of solid particle properties on the thermal performance of a packed-bed molten-salt thermocline thermal storage system

In this study we present a transient two-dimensional dispersion–concentric (D–C) model for heat transfer and fluid dynamics in a packed-bed molten salt thermocline thermal storage system. Based on the developed model, the effects of solid particle properties including particle diameter and particle material on the heat transfer between molten salt and solid particles are investigated with emphasis on detailed temperature distributions within solid particles. The results show that heat transfer between solid particles and molten salt can be significantly influenced by particle diameter. Increasing the particle diameter reduces heat transfer rate between solid particles and molten salt, and finally results in a decrease in the effective discharging time and discharging efficiency. It is also found that the effect of solid material on the thermal performance is influenced by the particle diameter. When particle size is small enough, the efficiency of the thermocline system is nearly independent of the solid material. For large particle diameters, heat discharge rate from solid particles to molten salt may be reduced if the thermal conductivity of solid particle is too low.

Determining the unique refractive index properties of solid polystyrene aerosol using broadband Mie scattering from optically trapped beads

A method is described to measure the refractive index dispersion with wavelength of optically trapped solid particles in air. Knowledge of the refraction properties of solid particles is critical for the study of aerosol; both in the laboratory and in the atmosphere for climate studies. Single micron-sized polystyrene beads were optically trapped in air using a vertically aligned counter-propagating configuration of focussed laser beams. Each bead was illuminated using white light from a broadband light emitting diode (LED) and elastic scattering within the bead was collected onto a spectrograph. The resulting Mie spectra were analysed to accurately determine polystyrene bead radii to ±0.4 nm and values of the refractive index to ±0.0005 over a wavelength range of 480-700 nm. We demonstrate that optical trapping combined with elastic scattering can be used to both accurately size polystyrene beads suspended in air and determine their wavelength dependent refractive index. The refractive index dispersions are in close agreement with reported values for polystyrene beads in aqueous dispersion. Our results also demonstrate a variation in the refractive index of polystyrene, from bead to bead, in a commercial sample. The measured variation highlights that care must be taken when using polystyrene beads as a calibration aerosol.

Nano-Engineering of Concrete

This paper summarizes recent developments in the field of nanoindentation analysis of highly heterogeneous composites. The fundamental idea of the proposed approach is that it is possible to assess nanostructure from the implementation of micromechanics-based scaling relations for a large array of nanoindentation tests on heterogeneous materials. We illustrate this approach through the application to calcium-silicate-hydrate (C-S-H), the binding phase of all cement-based materials. For this important class of materials, we show that C-S-H exists in at least three structurally distinct but compositionally similar forms: low density, high density and ultra-high density. These three forms differ merely in the packing density of 5-nm sized particles. The proposed approach also gives access to the solid particle properties of C-S-H, which can now be compared with results from atomistic simulations. By way of conclusion, we show how this approach provides a new way of analyzing complex hydrated nanocomposites, in addition to classical microscopy techniques and chemical analysis. This approach will turn out invaluable in our quest of adding the necessary “green” value to a commodity, concrete, by nano-engineering higher strength and toughness from first principles.

Mixing Study in an Unbaffled Stirred Precipitator Using LES Modelling

This paper describes the CFD modelling of a reactor operating in the nuclear industry using LES approach. The reactor consists of an unbaffled stirred tank reactor in which plutonium precipitation reactions are carried out. The flow generated in such a precipitator is complex and there is very little information available in the literature about unbaffled reactors stirred with magnetic rod. That is why a hydrodynamic modelling has been developed using computational fluid dynamics (CFD) in order to get accurate description of mixing phenomena inside the precipitator and therefore to be able to predict the solid particle properties. Due to the strong turbulence anisotropy, the turbulence transport simulation is achieved by a large eddy simulation (LES) approach which gives unsteady solutions. The numerical simulations are performed in 3D using the Trio_U code developed at the Commissariat à l'Énergie Atomique. The predictive performances of the modelling are analysed through a mixing phenomena study. Both experimental and numerical studies are performed. This work shows how hydrodynamics inside the reactor can have a noticeable effect on the precipitate properties and how LES modelling is a very effective tool for the process control.

Relationship between Foam Stabilization and Physical Properties of Particles on Aluminum Foam Production

Experimental investigation of the foam stabilizing factors that influence aluminum foam fabrication is crucial to improve the foaming process. Solid particles contribute to an increase of the viscosity of the liquid phase and overall foam stability. Foam stability depends on the liquid type, wettability and the shape of solid particles. Even though a poor wettable particle contributes effectively to enhance liquid viscosity, the particle leads to the collapse of the foam cell due to the poor energy balance at the interface between the solid and the liquid. In our study, the effect of particles was investigated using both water solutions and an aluminum melts. We show that not only the relative viscosity, but also the physical properties of solid particles need consideration during aluminum foam production.

Correlation for Prediction of Minimum Fluidization Velocity and Riser Liquid Holdup in Three-Phase External Loop Air Lift Fluidized Bed Reactor

The effect of superficial gas and liquid velocities and properties of solids on the minimum fluidization velocity and riser liquid holdup of a three-phase external loop air lift fluidized bed reactor was characterized using Newtonian and non-Newtonian systems. Water, 65% and 85% of glycerol and n-Butanol were used as Newtonian liquids and different concentrations of carboxymethyl cellulose (i.e. 0.2%, 0.5% and 1% CMC) were used as non-Newtonian liquids. Spherical glass beads, bearl saddles and rasching rings of different sizes were used as solid phases. The phase flow rates and properties of solid particles had significant effects on the hydrodynamic characteristics of the external loop air lift fluidized bed reactor, such as minimum fluidization velocity and riser liquid holdup. Unified correlations have been developed to estimate the minimum fluidization velocity and riser liquid holdup as a function of superficial phase velocities, properties of solid particles and physical properties of both Newtonian and non-Newtonian liquid systems. The predicting ability of the correlations were tested with the experimental data and found to be a good fit with an absolute average relative deviation (AARD) of ± 6.5 % and ± 7.8 % for minimum fluidization velocity and riser liquid holdup, respectively.

Restrictions on MMM Industrial Data to Build PCA Models

Abstract Mining, mineral and metal (MMM) processes present by its nature (multiphase, with solid particle properties distribution, high temperature) difficult scenarios to obtain high quality measurements of key variables. Furthermore, the characteristics of the feed are almost always changing over time, upsetting the process and giving a hard time to the stabilizing controllers. Then steady state operation condition is seldom met. Even more, some key measurements as metal grades and particle size are usually sparsely obtained with complex procedures involving sampling handling and correlations methods. All this characteristics put a lot of pressure on maintenance procedures of installed instrumentation. In summary, there are plenty of opportunities that sets of observations collected from a data base may contain all kind of pitfalls. Multivariate statistics can provide us with very powerful tools to analyze large set of data, and to efficiently extract the relevant information. However, the set of data must contain this information with the less degree of confusion as possible, for example as the result of a designed experiment. In this work, the application of these methods to smelters and flotation plants data are discussed. Special emphasis is put on how the previous work to assure the quality of the data, used in building such models, plays an important role on the success or failure of a powerful methodology.

Sedimentation and Flocculating Properties of Solid Particles in Enzymatic Treated Rice Washing Drainage and its Electrostatic Properties

Sedimentation and Flocculating Properties of Solid Particles in Enzymatic Treated Rice Washing Drainage and its Electrostatic Properties

Effect of fine solid particles on absorption rate of gaseous CO2

The influence of the properties of solid particles in slurry on the absorption of CO2 in the slurry was investigated in a stirred thermostatic reactor. The absorption experiments were carried out in three different slurries consisting of water, cyclohexane and soybean oil, respectively, and three kinds of solid particles (active carbon, active alumina and silica gel) were incorporated into each of the above mentioned slurries separately. The experimental results show that the active carbon particles could enhance the absorption rate of gaseous CO2 in the aqueous slurry, while in the cyclohexane slurry, active carbon particles indicated no the absorption enhancement effect. However, it was observed that the active alumina and silica gel particles could enhance the absorption rate of CO2 in the cyclohexane slurry. These phenomena indicate that the solid particles, which could enhance the gaseous CO2 absorption rate, should possess two properties simultaneously, i.e. they rejected the solvent and had higher adsorption capacity for the solute. The experimental results also show that, as for those solid particles which could enhance the gas absorption rate, the enhancement increased quickly with the increase of solid concentration in slurry at first, and then reached a constant value gradually. It was also found that the enhancement factor was related to the coverage fraction of solid particles on the gas-liquid interface, and due to the reduction of surface fraction with increasing stirred speed, the enhancement factor decreased.

Sedimentation and Flocculating Properties of Solid Particles in Enzymatic Treated Rice Washing Drainage and Its Mechanism

Sedimentation and Flocculating Properties of Solid Particles in Enzymatic Treated Rice Washing Drainage and Its Mechanism