Proper Particle Size Distribution Research Articles

Controlling particle size of levan in powder form with different technologies

Levan is a fructose polysaccharide with multiple applications in different fields, but its obtaining in powdered form with a narrow particle size distribution is a complicated task. Two techniques, electrospraying and supercritical antisolvent (SAS) precipitation, were used to process levan that was first obtained enzymatically. The SAS process was able to micronize the polymer (at experimental conditions far above the mixture critical point of the solvent-antisolvent system) to obtain spherical particles between 0.30 and 0.50 μm with a proper particle size distribution. In this case, the Peng-Robinson equation of state was used to theoretically determine the mixture critical point. Bigger and elongated particles were obtained with electrospraying (0.60 μm). According to solution properties, mainly rheology, solubility and conductivity, the best solvent for levan electrospraying, in order to avoid problems of solvent evaporation and jet formation, was a mixture of water and ethanol with a polymer concentration of 50 mg·cm−3. Indeed, that solution has a viscous behavior (according to the oscillatory analysis), a low degree of pseudo-plasticity (based on the shear flow analysis), and the highest value of conductivity. Therefore, the particle size distribution of levan in powdered form can be tuned depending on the technique used.

Numerical investigation on dynamic performance of vertical hydraulic transport in deepsea mining

Owing to great demands of natural resource and huge reserves of seabed minerals, deepsea mining technology has been proposed in the past decades. The most promising way to convey the deepsea ores to the sea surface is vertical hydraulic transport (VHT). Numerical investigations on dynamic performances of VHT were conducted by Computational Fluid Dynamics and Discrete Element Method (CFD-DEM). The convergence study on the pipe length, simulation duration, spacial and temporal resolutions were carried out, followed by the method validation through the experiments. The characteristics of particle and fluid were analyzed from different aspects. In most conditions, the local volume concentration of particles in the pipe is larger than the feeding concentration owing to the velocity lag of particles in the upward flow, indicating that instantaneous particle characteristics should be considered in engineering applications. Sensitivity analyses of transporting parameters and particle properties were conducted. Flow velocity and feeding concentration are two key factors dominating the dynamics of the mixture. A special range of particle diameter was recognized in which the particle accumulation was severe, whereas a proper particle size distribution would benefit VHT. Based on the numerical simulations, empirical formulas were proposed to have a rough estimation of particle velocity, slip velocity and local concentration for the initial design of VHT.

Optimizing selection method of continuous particle size distribution for lost circulation by dynamic fracture width evaluation device

The increase in the pressure bearing capacity is critical for mitigation of lost circulation, and to do so the strength of the plugging zone should be increased via picking an effective evaluation method and choosing the proper particle size distribution (PSD). Therefore, in order to successfully investigate this process, the traditional evaluation device of lost circulation should be improved for dynamic variation of fracture width to find the optimized plugging materials. This means, a new testing apparatus device capable of testing dynamic fracture width should be developed. Additionally, commonly used selection criteria of PSD are incapable of providing us with a continuous PSD curve since they only fulfill discrete PSDs. To overcome these two obstacles, a variety of continuous PSD models based on a new testing device and method are examined. Likewise, the impact of governing parameters and an optimized PSD selection criterion were studied with a specific lost circulation material (calcium carbonate) and concentration in a water-based drilling fluid. The experimental results demonstrate that the normal distribution model provides the best selection result while the sensitive analysis indicate that the factors influencing pressure bearing capacity in a sequential order are: minimum particle size, standard deviation, maximum particle size and average value. Besides, the optimized experiments illustrated that the maximum particle size should be 1.3 times of the maximum fracture width and the minimum particle size should be 0.8 times of the average fracture width. Moreover, the average value should be equal to the optimal particle average size and the standard deviation should be 0.3 times of the particle average size. It was found that the optimized selection method results in the highest plugging efficiency compared to conventional selection criteria. Collectively, the new device and optimal assessing approach would improve the prediction accuracy of pressure bearing capacity to select an appropriate PSD with varying of fracture width in field operations.

Synthesize of magnetite Mg-Fe mixed metal oxide nanocatalyst by urea-nitrate combustion method with optimal fuel ratio for reduction of emissions in diesel engines

Abstract In the present study, Mg0.25Fe2.75O4 nanocatalyst for reduction of emissions in diesel engine was fabricated via urea-nitrate combustion method. The effect of urea concentrations as fuel on its structural characteristics and Oxygen Storage Capacity (OSC) was thoroughly investigated. The results of various characterization analyses showed that fuel ratio significantly affects crystallinity, textural, size and morphology of particles, and thermal stability of nanocatalyst. These are mainly due to increase in combustion temperature and duration. The Mg0.25Fe2.75O4 fabricated at fuel ratio of 2.5 times of stoichiometric ratio exhibited the lowest weight loss/high crystallinity (less than 1 wt %) and lowest lattice parameter (8.346 A) which are related to well diffusion of Mg cations into ferric oxide as host. The Raman and FTIR analyses showed the existence of strong peaks correspond to formation of tetrahedral and octahedral sublattices and also the formation of spinel structure of MgFe2O4. The reduction in crystalline size, obtained with higher amount of fuel, resulted in a higher surface area (23.6 m2/g), higher pore volume (0.0950 cc/g) and proper particle size distribution (25–35 nm). These cause a better catalytic activity. Moreover, the enhanced OSC (8661 μmol H2/g) along with shifting the reduction peaks to lower temperatures, as major attributes in relation to catalytic technologies, confirmed the strong effect of fuel ratio of 2.5 on fabrication process of Mg0.25Fe2.75O4. Finally, the highest reduction in HC (33%), CO (14-17%), PM1.0 (16%), and CO2 (12%) achieved, using the optimum sample-mixed diesel fuel at 90 ppm.

Preparation and Properties of Spherical Mo Powders by Plasma Rotating Electrode Process for Additive Manufacturing

Since molybdenum has very high melting point of 2620 °C, there are many difficulties in its forming and post-processing, especially for deep processing. Furthermore as molybdenum is expensive, the utilization rate is important for the molybdenum processing. Additive manufacturing can directly manufacture the parts without mold and increase the utilization rate, and brings an opportunities for the new direction of deep processing for molybdenum. Due to the high quality requirements of molybdenum powder in additive manufacturing technology, the high-quality spherical molybdenum powder was prepared by plasma rotating electrode process method in the present study. The morphology, particle size and particle size distribution, chemical and physical properties were investigated. The molybdenum powder prepared by plasma rotating electrode process method showed to have high purity, high sphericity, good fluidity and high bulk density, proper particle size distribution and low gap element within the powder. The microstructure of the powder was a mixed structure of dendrites and cell crystals formed by rapid solidification, and as the particle size of the powder gradually decreased, the microstructure of the powder surface was remarkably refined. Within a certain range, the molybdenum powder with a wide particle size distribution had better fluidity and higher bulk density. The high-quality spherical molybdenum powder was prepared by plasma rotating electrode process method, which can meet the requirements of additive manufacturing technology for powder material performance.

Synthesis and characterization of carbon-based MgO catalysts for biodiesel production from castor oil

The main purpose of this work was to develop a highly efficient and stable solid base catalyst for the preparation of biodiesel to meet the needs for green and clean production. To this end, a series of carbon-based magnesium oxide (MgO) solid base catalysts with high specific surface area were prepared by a sol-gel method and calcination for biodiesel production from castor oil. The effects of different organic additives and calcination temperatures on the physicochemical properties of catalysts were analyzed and evaluated by XRD, SEM, EDX, BET, FTIR and TGA. SEM and BET results indicated that the carbon-based MgO catalysts have a proper particle size distribution and a higher specific surface area. Meanwhile, EDX and TG analysis evidenced the presence of residual carbon in the MgO samples, which was confirmed to have a positive effect on the performance of the catalysts. The transesterification reaction was carried out in a batch reactor with condensed reflux to assess the performance of the catalysts. The MgO-UREA-800 catalyst exhibited impressive catalytic performance and an optimum biodiesel yield of 96.5% was obtained at the molar ratio of ethanol to oil of 12:1, catalyst loading of 6 wt%, reaction temperature of 75 °C and reaction time of 60 min. The catalyst durability tests showed that the catalysts could be reused in five cycles of operation without significant losses in activity.

Eco-friendly castor oil-based UV-curable urethane acrylate zinc oxide nanocomposites: Synthesis and viscoelastic behavior

Attention to environmental problems and the importance of maintaining it have caused the researchers to pay more attention in this regard. The production of polymers and resins has increased in recent years and has affected by environmental pollution due to their long-term degradation. An appropriate solution to this problem is the synthesis of degradable and environmentally friendly polymers and resins. Using natural materials in the synthesis of polymers and resins can help them to be environmentally friendly. The purpose of this research is to synthesize urethane acrylate resins using natural resources. For this purpose, the urethane acrylate pre-polymer was synthesized with castor oil. Then, using modified zinc oxide nanoparticles with 1, 3 and 5 wt% urethane acrylate zinc oxide nanocomposites were produced. The use of castor oil as a degradable part and lack of organic solvent in radiation systems led to the creation of an environmentally friendly resin. Subsequently, the viscoelastic behavior of the prepared nanocomposite was evaluated. Spectrometry results confirm the synthesized resin structure. The morphology of nanocomposites confirmed the proper particle size distribution in a 3 wt.% sample. The results of the dynamic mechanical thermal analysis test showed that increasing the amount of modified nano ZnO could increase the glass transition temperature, and the maximum value was observed in 5 wt.% modified nano ZnO (69.7℃).

Retrieval of Snow Properties for Ku- and Ka-band Dual-Frequency Radar.

The focus of this study is on the estimation of snow microphysical properties and the associated bulk parameters such as snow water content and water equivalent snowfall rate for Ku- and Ka-band dual-frequency radar. This is done by exploring a suitable scattering model and the proper particle size distribution (PSD) assumption that accurately represent, in the electromagnetic domain, the micro/macro-physical properties of snow. The scattering databases computed from simulated aggregates for small to moderate particle sizes are combined with a simple scattering model for large particle sizes to characterize snow scattering properties over the full range of particle sizes. With use of the single scattering results, the snow retrieval look-up tables can be formed in a way that directly links the Ku- and Ka-band radar reflectivities to snow water content and equivalent snowfall rate without use of the derived PSD parameters. A sensitivity study of the retrieval results to the PSD and scattering models is performed to better understand the dual-wavelength retrieval uncertainties. To aid in the development of the Ku- and Ka-band dual-wavelength radar technique and to further evaluate its performance, self-consistency tests are conducted using measurements of the snow PSD and fall velocity acquired from the Snow Video Imager/Particle Image Probe (SVI/PIP) during the winter of 2014 in the NASA Wallops flight facility site in Wallops Island, Virginia.

Improvement of Resistance to Slag Penetration in Magnesia-Based Refractory with Colloidal Alumina Addition II by Means of a Proper Particle Size Distribution of MgO

By addition of colloidal alumina, three different particle sizes of dead burnt MgO were employed as raw materials to prepare MgO-based spinel substrates at 1773 K (1500 °C). It was found that the particle size of MgO, as well as its size distribution, had substantial impact on the resistance of the refractory to the slag penetration at 1873 K (1600 °C). Using relatively small particles of MgO (<0.5 mm) can efficiently limit the slag penetration, due to the formation of solid phases (CaO·Al2O3 and CaO-MgO-Al2O3) at the grain boundaries. A particularly significant improvement against the slag penetration was found on MgO substrates with a proper particle size distribution in a size range of 0-1 mm. The improvement could be mainly related to the higher density and distribution of spinel phase in the MgO matrix, which is mostly located at the borders of large MgO particles.

Experimental Study on Solid Discharge Rate from a Nonmechanical Solid Feeding System

A nonmechanical solid feeding device uses aeration gas in combination with its geometrical shape to cause particulate solids to flow through it. Serious erosion of moving parts, high solid flow rate requirement, and high operating temperature preclude the use of mechanical solid feeders. A nonmechanical solid feeding system was designed and developed in the Chemical Engineering Division of Bhabha Atomic Research Centre for continuous solid addition to the fluidized bed. The controlled continuous solid addition fulfills various purposes – maintain proper particle size distribution inside fluidized bed, provide make up for entrained solids, and supply solid reactant where solids are consumed in reaction. A solid circulation vessel which works on the principle of compartmented fluidized bed was the heart of this solid feeding system. It consists of two compartments (main and riser), and the compartments were connected through an orifice. Solid discharge rate from solid circulation vessel was regulated by adj...

Effect of particlesize of blast furnace slag on properties of portland cement

Fineness is one of the key factors in determining the hydration activity factor of slag. The present research investigates the effect of particle size distribution (PSD) of slag on water requirement, setting time, and compressive strength. For this purpose, a reference and 17 cement samples containing different blast furnace slag are made and the properties are tested. When slags with proper PSD are prepared the cement properties can be better than the reference.

Estimation of particle size distribution from cross-sectional particle diameter on the cutting plane

To control highly functional sintered materials, it is necessary to evaluate particle size segregation within materials. In the present study, a new method for estimating particle size distribution is proposed; this method considers the occurrence probability of the cutting diameter. The proper particle size distribution in a particle bed was estimated by calculating a matrix consisting of the occurrence probability and the distribution of particle diameters measured on a cutting plane. The estimated particle size distribution was smoothed using the Phillips–Twomey method. A cavity-filling simulation was carried out to verify the validity of the proposed method using the Distinct Element Method. The particle size distribution estimated by this method correlated well with the actual particle size distribution. The effect of particle size distributions with various geometrical standard deviations on the accuracy of estimated values was also investigated. The accuracy increased as the geometric standard deviation increased, and there was an optimum particle size bin number for a specific particle distribution. It was found that a large bin number and a large number of measured particles were required to obtain a higher accuracy for narrow size distributions.

2D DEM simulation of particle mixing in rotating drum: A parametric study

Mixing behaviors of equal-sized glass beads in a rotating drum were investigated by both DEM simulations and experiments. The experiments indicated that higher rotation speed can significantly enhance mixing. The particle profiles predicted by 2D DEM simulation were compared with the experimental results from a quasi-2D drum, showing inconsistency due to reduction of contacts in the single-layer 2D simulation which makes the driving friction weaker than that in the quasi-2D test, better results could be reached by specifying a higher frictional coefficient between the particles and the cylinder wall. In order to explore the influences of physical properties (density, size or friction) on mixing behavior, numerical 2D simulations were carried out systematically, in which one examined specific property being examined was exaggerated while the others were kept the same as that in the control group. The DEM simulations reveal that particle density and size are the dominating factors affecting mixing behaviors, while the effect of frictional coefficient is less significant. However, segregation due to any of the factors can be diminished by specifying a proper particle size distribution (multi-size with lower size ratio).

The effect of reducing alfalfa hay cut length on TMR particle size distribution, rumen pH and chewing activity of cows in early lactation using Penn State Particles Separator(PSPS)

The ability of a ration to meet the nutritional needs of a high yielding dairy cow requires understanding of both the chemical and physical characteristics of the ration (NRC, 2001). Having the proper particle size distribution (2 to 8 percent of the particles on the upper sieve, 30 to 50 percent on the middle and lower sieves, and no more than 20 percent on the bottom pan) of feeds is an important part of ration formulation. Chopping the crop at the proper length produces forages that can be combined to achieve the desired particle length in a TMR. The dairy cow’s need for increasingly higher levels of energy have led to diets relatively high in concentrates. However, cows still require adequate fibre in the ration to function properly (Allen, 2000). Adequate forage particle length is necessary for proper rumen function and reduced forage particle size has been shown to decrease the time spent chewing and cause a trend toward decreased rumen pH. When cows spend less time chewing, they produce less saliva, which is needed to buffer the rumen. The objective of this study was to evaluate the effects of reducing alfalfa hay length of cut on TMR particle size distribution, rumen pH and chewing activity using penn state particles separator.

Optimizing High-Temperature Kill Pills: The Åsgard Experience

Summary Historically, the survival rate for conventional, nondamaging polymer/carbonate kill pills under elevated temperatures was limited. Accordingly, a development program was instituted to develop a new high-temperature kill pill that would possess superb bridging characteristics on a high-permeability proppant while remaining thermally stable at temperatures exceeding 165°C (329°F). This paper describes the development of a sodium formate kill pill geared specifically for the demanding Åsgard development in the Norwegian North Sea. The pill was engineered and successfully applied in a high-temperature application to seal a high-permeability (400 to 500 darcys) frac-pack sand in the Smørbukk field. In the field, the newly engineered formate-based pill proved to be thermally stable while providing sufficient leakoff control. Furthermore, the development reinforced the critical role of proper particle-size distribution (PSD) in minimizing fluid invasion. With an emphasis on the PSD, this paper reviews the relative formation-damage potential testing procedure of the new formulation on simulated fracture packs. In the laboratory, the fluids demonstrated excellent thermal stability after long-term exposure to temperatures exceeding 150°C (300°F). The aging process was started simultaneously with two samples of each pill and concluded at the end of 16 and 72 hours, respectively. Leakoff tests were performed on 16/30 proppant at 165°C (329°F), resulting in minimal filtration. This paper also examines the unusually demanding conditions at Åsgard relative to other Norwegian fields and details the application and performance of the new kill pill in this hostile downhole environment.

98/00052 Coal pond fines cleaning with classifying cyclones, spirals, and column flotation

Large reserves of coal pond fines arc found in the Illinois Basin--over 40 million tons in Western Kentucky, over 65 million tons in Southern Illinois, and over 35 million tons in Southern Indiana. If these fines are used to produce coal-water slurry (CWS), fuel costs, NO{sub x} emissions, and pond closure costs can be reduced. Coal fines from this region that are used to produce CWS for co-fire or re-burn may require processing, however, to attain proper particle size distribution and fuel quality. To evaluate the effectiveness of using coal cleaning technologies to control these CWS quality parameters, a simple flowsheet for recovering and processing coal pond fines was designed and tested. Coal fines processing consisted of using classifying cyclones to size at nominal minus 200 mesh, cleaning the classifying cyclone underflow using spirals, and cleaning the overflow using column froth flotation. Ash content of the dean coal from the spiral was reduced to about 10 percent, winch is satisfactory to use for CWS co-firing in a cyclone-fired boiler. The clean coal from column flotation may be used for re-burn in a cydone-fired boiler or as co-fire fuel in a wall-fired or tangentially-fired boiler Heating value recovery during laboratory scale,more » pilot-scale, and commercial-scale coal cleaning testing was about 80 percent.« less

Some Effects of Size Distribution on Particle Bridging in Lost Circulation and Filtration Tests

Introduction A common cure of lost circulation is the introduction of granular bridging agents into the mud system. Many materials, such as ground nut shells, are used for this purpose. If the trouble causing void (fracture, fissure, vug, etc.) is not too large, the granular agent forms a "bridge" across or within the opening. Successively smaller particles in the mud stream then accumulate on and/or within this bridge until normal filtration is finally established. The efficiency of many bridging agents has been studied in the laboratory using various slot testers. Many investigators have remarked that a granular bridging material should have the proper particle size distribution. With the exception of the broad range specified in the patent of Goins and Nash, there is apparently no definition as to what this distribution should be. A bridge may be initiated when several particles of lost circulation material lodge against each other in a fracture or other void. Smaller particles then may bridge the openings between the larger, previously bridged particles. This process continues until the voids become quite small and the problem becomes one of filtration. It would seem logical that an optimum particle size distribution exists, i.e., one containing the proper quantity of properly sized material to fill the successively smaller voids of the bridge. The filtration characteristics of drilling fluids may be subject to a similar analysis. It has been clearly demonstrated by many workers that the filtration behavior of various muds can be altered by particle size control. Slusser, et al, divided filtration into three periods and showed that particle sizes affecting a given period did not necessarily affect other portions of the filtration curve. An analagous problem is the proper sizing of gravel, liner slots and screen sizes in various sand-exclusion problems. Here the situation is reversed in that a proper "void" size, rather than the size of the bridging agent, is sought.