Flow Synthesis of Biocompatible Fe3O4 Nanoparticles: Insight into the Effects of Residence Time, Fluid Velocity, and Tube Reactor Dimension on Particle Size Distribution

Pure pyrazinamide has been produced in a coupled flow synthesis and crystallisation in high yield, pure polymorphic form (γ) and narrow particle size distribution.

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Impacts of combustion phasing, load, and speed on soot formation in spark-ignition engines

International Journal of Engine Research ◽

10.1177/1468087419836584 ◽

2019 ◽

Vol 21 (3) ◽

pp. 514-539

Author(s):

Mitchell D Hageman ◽

David A Rothamer

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Residence Time ◽

Engine Speed ◽

Soot Formation ◽

Direct Injection ◽

Spark Ignition ◽

Spark Ignition Engine ◽

The Impact

The premixed prevaporized engine operation method was used to study the effects of main combustion thermodynamic properties and residence time on soot formation in a spark-ignition engine. Select cases were repeated under early-injection, nearly homogeneous, spark-ignition direct-injection operation to determine if the impact of the investigated parameters was the same or if the impact of in-cylinder liquid fuel injection and the resulting heterogeneous fuel-air mixture alters the trends. The original premixed prevaporized study hypothesized that soot is more likely to form after main combustion than during the main combustion event under completely homogeneous conditions. This hypothesis was tested in this study by performing premixed prevaporized combustion phasing sweeps at equivalence ratios (Φs) of 1.35 and 1.40. Both sweeps showed low sensitivity of the particle size distribution to significant changes in peak temperature and pressure during combustion, providing supporting evidence for the original hypothesis. This information was then used to design experiments to isolate the impacts of pressure (engine load) and residence time (engine speed). A premixed prevaporized load sweep showed that particulate emissions increase as a function of load/pressure. A spark-ignition direct-injection load variation showed similar pressure dependence for cases with in-homogeneous in-cylinder fuel-air distributions. A premixed prevaporized residence time variation (performed by changing engine speed) demonstrated an increase in soot formation with increased residence time. The results for identical spark-ignition direct-injection residence-time variations suggest a trade-off in soot formation between the effects of increased mixing time and increased residence time for spark-ignition direct-injection operation. The premixed prevaporized load and speed points were each investigated using Φ sweeps to determine the critical enrichment threshold for soot formation (ΦC) and the dependence of soot formation for Φ > ΦC. The spark-ignition direct-injection investigations were performed at Φ = 0.98, such that any soot formation above the non-fuel-related baseline particle size distribution could be attributed either to mixture heterogeneity or in-cylinder fuel films.

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Study on the Process and Characteristics of Clogging for Ceramic Permeable Brick

Advances in Civil Engineering ◽

10.1155/2021/8481571 ◽

2021 ◽

Vol 2021 ◽

pp. 1-10

Author(s):

Zizeng Lin ◽

Hai Yang ◽

Huiming Chen

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Pore Structure ◽

Size Distribution ◽

Permeability Coefficient ◽

Simulated Rainfall ◽

Experimental Conditions ◽

Internal Pore Structure ◽

Internal Pore ◽

Insight Into

A ceramic permeable brick was selected for study in a device that was designed to fully investigate the process and characteristics of clogging in permeable bricks. In order to evaluate the permeability influenced by clogging, a simulated rainfall was filtered through the permeable brick placed in an innovative device. The macroscopic and microscopic changes in the brick and the filtrate were all measured to fully investigate the causes and process of clogging. Then, the mechanism of clogging in the permeable brick pores was further discussed. The results showed that the clogging risk of permeable brick was extremely high, and it can result in a complete clogging in only 5–10 years under the experimental conditions. The permeability coefficient and porosity both decreased exponentially with the increase in filtrate, which was attributed to the clogging of the internal pore structure due to particle interception. The chord size distribution results stressed that the blockage mainly occurred in the upper layer pores in the range of 0.5–1.5 mm, which is relatively sensitive to clogging due to the particle size distribution in rain water. The particle size distribution of the influent and effluent indicated that the clogging process could completely remove particles larger than 88 µm but showed variable removal efficiency for particles with sizes of 20–88 µm. This research offers new insight into the clogging of permeable bricks and provides theoretical guidance for restoring the brick permeability.

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Synthesis of Titania Powder by Titanium Tetrachloride Oxidation in an Aerosol Flow Reactor

MRS Proceedings ◽

10.1557/proc-249-139 ◽

1991 ◽

Vol 249 ◽

Cited By ~ 1

Author(s):

M. Kamal Akhtar ◽

Yun Xiong ◽

Sotiris E. Pratsinis

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Residence Time ◽

Titanium Tetrachloride ◽

Flow Reactor ◽

Geometric Standard Deviation ◽

Process Conditions ◽

Average Particle ◽

Powder Size

ABSTRACTVapor phase synthesis of titania particles by oxidation of titanium tetrachloride (TiCI4) was studied in an aerosol reactor between 1200 K and 1723 K. The effect of process variables (reactor residence time, temperature, reactant concentration) on powder size and phase characteristics was investigated using the differential mobility particle sizer, scanning electron microscopy and X-ray diffraction. The morphology of the particles remained unchanged under the process conditions investigated; titania particles were primarily anatase though the rutile weight fraction increased with increase in reactor temperature. The geometric number average diameter of the particles was between 0.13 µm and 0.35 [m and the geometric standard deviation of the particle size distribution was about 1.4. The average particle size increased with increasing temperature, TiCI4 concentration and residence time. The observed changes in the particle size distribution were compared with those predicted by solving the aerosol dynamic equation by a sectional method and accounting for coagulation and first order chemical reaction.

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A procedure for the design of protective filters

Canadian Geotechnical Journal ◽

10.1139/t07-005 ◽

2007 ◽

Vol 44 (4) ◽

pp. 490-495 ◽

Cited By ~ 7

Author(s):

G L. Sivakumar Babu ◽

Amit Srivastava

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Relative Density ◽

Size Distribution ◽

Analytical Procedure ◽

Filter Material ◽

Seepage Velocity ◽

Base Soil ◽

Insight Into

Current procedures for the design of filters to protect the soil from erosion and piping are solely based on particle-size distribution (PSD) curves of the filter medium and base soil. In the present work, an analytical solution is presented in a single derivation for the design of the filter, which takes into account factors like pore size, permeability, and factor of safety against soil boiling conditions. The solution obtained from the proposed analytical procedure provides insight into the role of seepage velocity, relative density of the filter material, and the ratio of filter density to base soil density on the performance of the filter.Key words: filter, erosion, particle-size distribution, permeability, seepage velocity, relative density.

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Particle Lagrangian CFD Simulation and Experimental Characterization of the Rounding of Polymer Particles in a Downer Reactor with Direct Heating

Processes ◽

10.3390/pr9060916 ◽

2021 ◽

Vol 9 (6) ◽

pp. 916

Author(s):

Juan S. Gómez Bonilla ◽

Laura Unger ◽

Jochen Schmidt ◽

Wolfgang Peukert ◽

Andreas Bück

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Residence Time ◽

Cfd Simulation ◽

Numerical Approach ◽

Particle Dispersion ◽

Direct Heating ◽

Residence Time Distributions ◽

Downer Reactor

Polypropylene (PP) powders are rounded at different conditions in a downer reactor with direct heating. The particles are fed through a single central tube, while the preheated sheath gas is fed coaxially surrounding the central aerosol jet. The influence of the process parameters on the quality of the powder product in terms of particle shape and size is analyzed by correlating the experimental results with the flow pattern, residence time distribution of the particles and temperature distribution predicted by computational fluid dynamics (CFD) simulations. An Eulerian–Lagrangian numerical approach is used to capture the effect of the particle size distribution on the particle dynamics and the degree of rounding. The simulation results reveal that inlet effects lead to inhomogeneous particle radial distributions along the total length of the downer. The configuration of particle/gas injection also leads to fast dispersion of the particles in direction of the wall and to particle segregation by size. Broad particle residence time distributions are obtained due to broad particle size distribution of the powders and the particles dispersion towards the wall. Lower mass flow ratios of aerosol to sheath gas are useful to reduce the particle dispersion and produce more homogenous residence time distributions. The particles’ residence time at temperatures above the polymer’s melting onset is determined from the simulations. This time accounts for the effective treatment (rounding) time of the particles. Clear correlations are observed between the numerically determined effective rounding time distributions and the progress of shape modification on the particles determined experimentally.

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Studies on Mean Residence Time of Fine Particles in a Powder-Particle Fluidized Bed. Effect of Particle Size Distribution, Static Electricity, and Humidity.

KAGAKU KOGAKU RONBUNSHU ◽

10.1252/kakoronbunshu.24.628 ◽

1998 ◽

Vol 24 (4) ◽

pp. 628-632 ◽

Cited By ~ 1

Author(s):

DAISUKE TANEDA ◽

TAICHIRO MASAGAKI ◽

KUNIO KATO

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Fluidized Bed ◽

Residence Time ◽

Powder Particle ◽

Mean Residence Time ◽

Fine Particles ◽

Static Electricity ◽

Effect Of Particle Size

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PENINGKATAN RECOVERY EMAS DI CARBON IN LEACH PLANT PT. ANTAM TBK UNIT BISNIS PERTAMBANGAN EMAS PONGKOR, JAWA BARAT (STUDI KASUS KADAR BIJIH 3,5 – 4,5 GPT DI PLANT 1)

Prosiding Temu Profesi Tahunan PERHAPI ◽

10.36986/ptptp.v1i1.49 ◽

2020 ◽

Vol 1 (1) ◽

pp. 49-58

Author(s):

Nurhakim Zafar ◽

Sudesno. Yudhistira ◽

Adiputra. Hoppy

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Residence Time ◽

Fine Fraction ◽

Gold Recovery ◽

Business Unit ◽

Mining Operations ◽

Recovery Plant ◽

Cyanide Consumption

ABSTRAK Sejarah pengolahan mineral emas di Unit Bisnis Pertambangan Emas (UBPE) Pongkor PT Antam Tbk menunjukkan adanya tren menurunnya kadar bijih. Meskipun demikian, metallugist di UBPE Pongkor PT Antam Tbk secara berkelanjutan mencari berbagai penyebab dan cara untuk meningkatkan nilai recovery Plant walaupun kadar bijih yang cenderung menurun. Berdasarkan hasil pengolahan data terhadap Plant 1 dan Plant 2 di UBPE Pongkor, menunjukkan adanya potensi perbaikan di area Plant 1 UBPE Pongkor PT Antam Tbk. Makalah ini akan berfokus pada pengurangan kadar emas dalam sand tailing saat kadar bijih antara 3,5 sampai 4,5 gram per ton (gpt) di Plant 1 dalam rentang 2 bulan. Berdasarkan hasil analisa data yang diperoleh dengan menggunakan metode Anova, diperoleh hasil bahwa fraksi halus, kadar sianida, dan waktu tinggal slurry adalah hal – hal yang paling berpengaruh dalam proses pengolahan emas di UBPE Pongkor. Serangkaian perbaikan dan inovasi dilakukan untuk menyelesaikan masalah ini, yaitu dengan cara memodifikasi distribusi ukuran grinding ball, mengatur waktu mixing dan injeksi sianida dalam tangki, serta mengatur waktu dan memonitoring waktu tinggal slurry di dalam tangki leaching dan CIL.Berdasarkan hasil perbaikan dan inovasi yang dilakukan, terlihat bahwa nilai recovery plant meningkat dari sebelumnya 89,4% menjadi 92,7%. Hal ini diperoleh dari nilai perbandingan distribusi ukuran bola 1 : 2 untuk grinding ball 40-60 mm dan 60-80 mm. Sementara itu, penyesuaian terbaik kadar CN adalah 600 - 650 ppm ditambah dengan optimalisasi injeksi sianida menggunakan pompa dosing sehingga dapat mengurangi waktu mixing sianida yang 3x sehari menjadi 1x sehari dan menurunkan kadar CN dari 1,23 menjadi 1,13 kg NaCN/ton bijih. Berdasarkan hasil pengaturan mill feeder dan pompa slurry, waktu tinggal di tangki leaching dari 51 jam menjadi 60 jam. Kata Kunci : Emas, recovery, fraksi halus, sianida, waktu tinggal slurry ABSTRACT History of mineral processing at Gold Business unit at PT Antam Tbk shows a consistent trend of decreasing grade due to intensive mining operations. Therefore, The Metallurgist PT Antam Tbk Gold Business Unit is looking for roots caused and solutions to raise up plant recovery although the grade of gold declined. After deep data analyzing process at plant 1 & 2, it’s shown that plant 1 at Gold Business Unit PT Antam Tbk have a room for recovery improvement. This research focus on reducing sand tailing to improved gold recovery at feed grade between 3.5 and 4.5 ppm at plant 1. Deep analysis was applied to processing big data from the plant using ANOVA Methode, it’s shown that fine fraction, Cyanide and slurry residence time were the major factor of gold recovery. Series improvement were applied to solved this problem, such as modifying grinding ball particle size distribution, adjusting cyanide feeding on leaching thank based on feed grade, and monitoring slurry residence time. It was observed that the plant plant 1 recovery was increasing from 89,4% to 92.7%. The best grinding ball particle size distribution was 1 : 2 for 50 & 80 mm grinding ball. While the best applied cyanide concentration was between 600 - 650 ppm with some modification to improve process control of cyanide feeding. It’s shown that cyanide mixing process was decreased from 3 times a day to only one a day and also the cyanide consumption was reduced from 1.23 to 1.13 kg/ton ore. Some modification also carried out to increase slurry residence time. It’s proved that by applying the improvement it’s shown that the slurry residence time rose from 50 h to 61 h. Keywords : gold, recovery, fine fraction, cyanide, residence time.

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Modelling of the Movement of a Prolate Particle in the Steady State Flow of a Non-Newtonian Fluid in an Inclined Annulus With Inner String Rotation

Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology ◽

10.1115/omae2019-95049 ◽

2019 ◽

Author(s):

Eric Cayeux

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Cross Section ◽

Slip Velocity ◽

Initial Conditions ◽

Fluid Velocity ◽

Bulk Fluid ◽

Tool Joint

Abstract The determination of the slip velocity, or whether a solid particle will sediment, during its transport is of prime importance for hole cleaning evaluations during drilling operations. Yet, this task is complexified by the asymmetry of the annulus when the central pipe axis does not coincide with the borehole central line and when the inner string rotates, especially since drilling fluids typically follow a yield stress power law rheological behavior. This paper describes the modelling of the movement of a particle in such conditions yet with the following simplifications: the inner tube is eccentric but has a uniform movement, the shape of the particle is assimilated to a prolate, the change of shear rates in the fluid around the slipping particle is neglected and collisions between particles are not considered. Otherwise, gravitational effects are incorporated by accounting for the mass density difference between the particle and the surrounding fluid mixture and by considering the borehole inclination. The particle spin is also estimated as it plays an important role in the determination of the drag and lift forces. The solution to the differential equations that describe the time evolution of the position and orientation of the particle, depend largely upon the initial conditions. Therefore, an ensemble of boundary conditions is generated at a starting cross-section along the annulus and the resulting particle trajectories are estimated. It is then possible to estimate a probabilistic slip velocity for particles of the considered dimensions, far away from the entrance region. This probabilistic approach allows to define a critical transport fluid velocity as the lower limit of the bulk fluid velocity by which no particle risk to settle. Similarly, one can define a critical settling fluid velocity as the upper limit of the bulk fluid velocity where every particle will sediment regardless of the initial conditions. With the described modelling of the particle movement and its associated statistical methods, it is possible to quantitatively estimate the spatial distribution of particles in any cross-section. For those particles that get trapped between the tool-joint and the borehole, it is then possible to estimate their size reduction by grinding, resulting from the rotation of the tool-joint on the borehole wall. The grinding process impacts the particle size distribution passed a tool-joint. By applying this method iteratively up to the annulus outlet, it is possible to estimate the particle size distribution of the drill-cuttings when they arrive at the shale-shakers.

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