Screen bowl centrifuge: a high-efficiency particle size separator

2008 ◽  
Vol 25 (2) ◽  
pp. 61-67
Author(s):  
M. K. Mohanty ◽  
B. Zhang ◽  
N. Khanna ◽  
A. Palit ◽  
B. Dube
Keyword(s):  
Particle Size ◽  
High Efficiency ◽  
Bowl Centrifuge

scholarly journals Awareness of aerosol-related transmission of COVID-19 among the dentists of Nepal

BDJ Open ◽  
2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Nashib Pandey ◽  
Buddha Bahadur Basnet ◽  
Sushmit Koju ◽  
Anju Khapung ◽  
Alka Gupta
Keyword(s):  
Social Sciences ◽  
Particle Size ◽  
High Efficiency ◽  
Emergency Services ◽  
Uv Light ◽  
Ventilation System ◽  
Age Groups ◽  
Air Filtration ◽  
Online Questionnaire ◽  
Dental Practitioners

Abstract Objective To access the awareness of dental practitioners of Nepal towards COVID-19 transmission through aerosols. Materials and methods The study involved 384 dentists from all over Nepal and was conducted for a period of 3 months. A self-reported online questionnaire was developed using Google forms and the link was shared. It emphasized the awareness related to the aerosol and ventilation system in their daily practices was prepared. The data were analyzed in Statistical Package for Social Sciences version 20.0 software. Results The majority of participants were female 52.9% (n = 203) and within the age groups of <30 years 57% (n = 219). Participants from Bagmati Province were 60.4% (n = 232), with least from Sudurpaschim Province 0.5% (n = 2). 60% of participants provided only emergency services during the COVID-19 pandemic and few (7%) provided consultations via telephone. The current ventilation system used was a well-ventilated room with open windows 65.4% (n = 251). However, 52.8% (n = 203) preferred specialized operatory incorporating high-efficiency particulate air (HEPA) filters and ultraviolet (UV) light. More than 60% of respondents were unaware of the particle size of the aerosol. Conclusions The obtained results signify the need for the proper ventilation system with appropriate air filtration systems in dental clinical setups.

Aluminate Green Phosphor with Small Particle Size Used for PDP via Co-Precipitation Method

2011 ◽  
Vol 295-297 ◽  
pp. 890-895
Author(s):  
Yan Dong ◽  
Yang Zhou ◽  
Xue Lin Han ◽  
Wei Jie Gu
Keyword(s):  
Particle Size ◽  
Phase Transformation ◽  
Small Particle ◽  
High Efficiency ◽  
Particle Growth ◽  
Solid State Reaction Method ◽  
Precipitation Method ◽  
Small Particle Size ◽  
Green Phosphor ◽  
Co Precipitation

Mg doped BaAl12O19:Mn2+ phosphor is one of the most efficient green phosphors for PDP. It is difficult to prepare the phosphor both have small particle size (< 3μm) and high luminescence. In the present work, a BaAl12O19:Mn2+ phosphor with small particle size was synthesized by the chemical co-precipitation method. Phase transformation and particle growth process during calcining process were investigated. The nucleation process was also discussed. The results show that, the phase transformation is complicated, the transition phases include BaCO3, γ-Al2O3, BaF2, BaAl2O4 and two phases contain Mn; The BaAl12O19 phase is formed from the reaction between BaAl2O4 phase and γ-Al2O3 phase, no a-Al2O3 phase appears during the entire process; The formation temperature of pure BaAl12O19 phase is 1200°C, which is lower than that in the high-temperature solid state reaction method. High efficiency BaAl12O19:Mn2+ phosphor with small particle size (< 2μm) and hexagonal flaky shape can be prepared by this method.

scholarly journals Influence of a Coaxial Electrospraying System on the n-Hexadecane/Polycaprolactone Phase Change Microcapsules Properties

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2205 ◽  
Author(s):  
Shengchang Zhang ◽  
Yuan Chen ◽  
Christine Campagne ◽  
Fabien Salaün
Keyword(s):  
Particle Size ◽  
Thermal Properties ◽  
Phase Change ◽  
Size Distribution ◽  
Encapsulation Efficiency ◽  
High Efficiency ◽  
Thermal Regulation ◽  
Coaxial Nozzle ◽  
Mean Diameter ◽  
Working Parameters

Electrospraying is considered to be a green, high-efficiency method for synthesizing phase change microcapsules (mPCMs) for possible applications in the fields of energy storage and thermal regulation. In this study, a coaxial nozzle was used to prepare n-hexadecane/polycaprolactone (PCL) microparticles. The objectives of this study were to investigate the influence of working parameters and solutions on morphology, particle size, thermal properties and encapsulation efficiency. Thus, three theoretical loading contents in n-hexadecane (30%, 50% and 70% w/w) and two concentrations of PCL (5 and 10% w/v) were used. The structures, morphologies and thermal properties of mPCMs were characterized by optical microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). Spherical microcapsules with a mean diameter of 10–20 µm were prepared. The increased concentration of n-hexadecane and PCL resulted in a change in the particle size distribution from a poly-disperse to monodisperse size distribution and in a change in the surface state from porous to non-porous. In addition, higher encapsulation efficiency (96%) and loading content (67%) were achieved by the coaxial nozzle using the high core-shell ratio (70/30) and 10% w/v of PCL. The latent heat of the mPCMs reached about 134 J.g−1. In addition, it was also observed that the thermal stability was improved by using a coaxial system rather than a single nozzle.

Particle Size Distribution of Micropowder in Jet Milling/Electrostatic Dispersion

2013 ◽  
Vol 815 ◽  
pp. 707-711
Author(s):  
Yin Bing Li ◽  
Rong Zhang ◽  
Peng Fei Yin ◽  
Jian Chang Hu ◽  
Li Min Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Particle Size Distribution ◽  
High Efficiency ◽  
Combined Process ◽  
Fine Powders ◽  
Innovative Method ◽  
Dispersion State ◽  
Jet Milling ◽  
Electrostatic Dispersion

Jet milling is an innovative method to prepare micropowder with high efficiency and pureness, while the particles obtained through this way exhibit a prominent agglomeration due to the electrostatic attraction caused by friction of particles during jet milling progress. Recently, we have developed a new method to prepare micropowder by combination of jet milling and electrostatic dispersion. In this paper, both fine powders of calcium carbonate and talc were produced by J/E method, the particle size and its distribution were evaluated by SEM and LPSA as well. The results of our research reveal that the dispersion state of the micropowder thus prepared is influenced by its properties and the combined process is effectiveness in powder pulverization and dispersion.

PENGARUH LAJU PREKURSOR SERBUK ALUMINIUM TERHADAP BENTUK MORFOLOGI NANOPARTIKEL ALUMINA DENGAN METODE THERMAL PLASMA

ROTOR ◽  
2017 ◽  
Vol 10 (1) ◽  
pp. 17
Author(s):  
Havid Arifian Rochman ◽  
Arief Ginanjar Dirgantara ◽  
Salahudin Junus ◽  
Imam Sholahuddin ◽  
Aris Zainul Muttaqin
Keyword(s):  
Particle Size ◽  
Aluminum Powder ◽  
Thermal Plasma ◽  
High Efficiency ◽  
Average Particle Size ◽  
Alumina Nanoparticles ◽  
Rate Variation ◽  
Average Particle ◽  
Dc Plasma ◽  
Simple Method

The synthesis of nanoparticles using thermal DC plasma method is a simple method for ease of installation and high efficiency is due to the rate of precursor that can be controlled. Micro-sized aluminum powder is synthesized using thermal DC plasma undergoing a process of evaporation as it passes through high temperature plasma flame, where kemuadian oxidized aluminum particles which evaporates the particles are split and binds with oxygen to form aluminum oxide or also known as alumina (Al2O3). In this experiment, the flow rate of oxygen plasma parameters at 35 SCFH (Standard Cubic Feet per Hour) and 20 amperes flows with precursors rate variation of 1.16 g / min, 3.19 g / min, and 3.5 g / min. Precursors used is 88 micro sized aluminum powder. To determine the morphology of nanoparticles of alumina testing scanning electron microscopy (SEM), the morphology form of nanosphere. Results of the analysis showed that the rate of precursor low causing agglomeration level slightly while the higher rate of precursor agglomeration rate also increased. At the rate of precursor 1.16 g / min, nanoparikel undergo agglomeration with an average particle size of 36.55 nm, and then at a rate of 3.19 gr precursor / mnt an average particle size of 46.49 nm, and at a rate of 3.5 gr / mnt an average particle size of 46.49 nm. The powder nanoparticles were then characterized using X-ray defraksi (XRD) where all alumina nanoparticles were synthesized showed alumina phase that is formed is a phase δ-Al2O3. Keywords: Alumina nanoparticles, DC Thermal Plasma, morphology, precursor rate, nanoparticles size, SEM, XRD.

Self-Cleaning Solar Mirrors Using Electrodynamic Dust Shield: Prospects and Progress

2014 ◽  
Author(s):  
Malay K. Mazumder ◽  
Mark N. Horenstein ◽  
Jeremy W. Stark ◽  
John N. Hudelson ◽  
Arash Sayyah ◽  
...  
Keyword(s):  
Power Generation ◽  
Particle Size ◽  
High Efficiency ◽  
Solar Collectors ◽  
Parabolic Trough ◽  
Atmospheric Dust ◽  
Efficient Operation ◽  
Dust Layer ◽  
Wide Range ◽  
Self Cleaning

Parabolic trough and power tower technologies provide inherent advantage of thermal energy storage and high efficiency of the Concentrating Solar Power (CSP) systems for utility scale solar plants. High efficiency CSP power generation with minimal water use is one of the SunShot goals of the US Department of Energy. The specular reflectance efficiency of the solar mirrors plays a critical role in the efficiency of power generation. The optical surface of the mirrors and the receiver must be kept clean for efficient operation of the plant. Some environmental challenges in operating the large-scale CSP plants at high reflectance efficiency arise from high concentration of atmospheric dust, wind speed and variation of relative humidity (RH) over a wide range. Deposited dust and other contaminant particles, such as soot, salt, and organic particulate matters attenuate solar radiation by scattering and absorption. Adhesion of these particles on the mirror surface depends strongly by their composition and the moisture content in the atmosphere. Presence of soluble inorganic and organic salts cause corrosion of the mirror unless the contaminants are cleaned frequently. In this paper, we briefly review (1) source of atmospheric dust and mechanisms involved in degradation of mirrors caused by salt particles, (2) loss of specular reflection efficiency as a function of particle size distribution and composition, and (3) an emerging technology for removing dust layer by using thin transparent electrodynamic screen (EDS). Feasibility of integration of EDS on the front surface of the solar collectors has been established to provide active self-cleaning properties for parabolic trough and heliostat reflectors. Prototype EDS-integrated solar collectors including second-surface glass mirrors, metallized acrylic film mirrors, and dielectric mirrors, were produced and tested in an environmental test chambers simulating desert atmospheres. The test results show that frequent removal of dust layer can maintain the specular reflectivity of the mirrors above 90% under dust deposition at a rate ranging from 0 to 10 g/m2, with particle size varying from 1 to 50 μm in diameter. The energy required for removing the dust layer from the solar was less than 10 Wh/m2 per cleaning cycle. EDS based cleaning could therefore be automated and performed as frequently as needed to maintain reflection efficiency above 90% and thus reducing water usage for cleaning mirrors in the solar field. A comparative cost analysis was performed between EDS and deluge water based cleaning that shows the EDS method is commercially viable and would meet water conservation needs.

scholarly journals Awareness of Aerosol related transmission of COVID-19 among the Dentists of Nepal

2021 ◽  
Author(s):  
Nashib Pandey ◽  
Buddha Basnet ◽  
Sushmit Koju ◽  
Anju Khapung ◽  
Alka Gupta
Keyword(s):  
Social Sciences ◽  
Particle Size ◽  
High Efficiency ◽  
Emergency Services ◽  
Uv Light ◽  
Ventilation System ◽  
Age Groups ◽  
Air Filtration ◽  
Online Questionnaire ◽  
Dental Practitioners

Abstract Objective: To access the awareness of dental practitioners of Nepal towards COVID-19 transmission through aerosols.Materials and Methods: The study involved 384 dentists from all over Nepal and was conducted for a period of three months. A self-reported online questionnaire was developed using Google forms and the link was shared. It emphasized the awareness related to the aerosol and ventilation system in their daily practices was prepared. The data were analysed in Statistical Package for Social Sciences version 20.0 software. Results: Majority of participants were female 52.9% (n = 203) and within the age groups of <30 years 57% (n = 219). Participants from Bagmati Province were 60.4% (n = 232), with least from Sudurpaschim Province 0.5% (n = 2). 60% of participants provided only emergency services during the COVID-19 pandemic and few (7%) provided consultations via telephone. The current ventilation system used was a well-ventilated room with open windows 65.4% (n = 251). However, 52.8% (n = 203) preferred specialized operatory incorporating high efficiency particulate air (HEPA) filters and ultraviolet (UV) light. More than 60% of respondents were unaware of the particle size of the aerosol.Conclusions: The obtained results signify the need for the proper ventilation system with appropriate air filtration systems in dental clinical setups.

Numerical Simulation and Experimental Studies for High Gas Velocity Electrostatic Precipitator

2012 ◽  
Vol 472-475 ◽  
pp. 2129-2132
Author(s):  
Cheng Wu Yi ◽  
Yun Qing Zhao ◽  
Rong Jie Yi ◽  
Tian Yin
Keyword(s):  
Particle Size ◽  
Dust Particle ◽  
High Efficiency ◽  
Electrostatic Precipitator ◽  
Collection Efficiency ◽  
Experimental Studies ◽  
Simple Algorithm ◽  
Gas Velocity ◽  
Geometry Model ◽  
Relationship Of

The high gas velocity electrostatic precipitator (HGVESP) is simulated by computational fluid dynamics (CFD) technology. The SIMPLE algorithm is used to calculate and the geometry model is divided by pre-processing software ICEM. The relationship of gas velocity, dust particle size and voltage is examined by FLUENT. The results suggest that with the improvement of applied voltage and dust particle size, collection efficiency increases. The results show that HGVESP with transverse plates can not only have a high efficiency, but also increase treatment capacity, which achieve miniaturization. Then the correctness of the model is verified by experiments.

scholarly journals A New Collector for Effectively Increasing Recovery in Copper Oxide Ore-Staged Flotation

Minerals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 595
Author(s):  
Renfeng Zhu ◽  
Guohua Gu ◽  
Zhixiang Chen ◽  
Yanhong Wang ◽  
Siyu Song
Keyword(s):  
Particle Size ◽  
Copper Oxide ◽  
High Efficiency ◽  
Average Particle Size ◽  
Economic Feasibility ◽  
Processing Plant ◽  
Average Particle ◽  
Entrainment Rate ◽  
Flotation Process ◽  
New Type

A new method, staged flotation for effectively increasing the recovery of ultra-fine copper oxide ore with a new type of collector (ZH-1, C3-5 carbon chain xanthate) is proposed for the first time. The flotation process and mechanism were examined by flotation tests, entrainment rate analysis, laser particle size experiments and microscopic imagery as well as economic feasibility analysis. It was demonstrated that the collector isoamyl sodium xanthate (ISX) shows a good collection ability (recovery exceeded 95%) for azurite, but the recovery was relatively much lower for malachite (only near 80%) due to the different particle size distribution. The new type of xanthate ZH-1 has shown a high-efficiency collection performance for fine-grained malachite. The recovery achieved for −10 μm malachite was more than 95% when the ZH-1 dosage was 150 mg/L, while the average particle size of −10 μm malachite sharply increased from 4.641 μm to 9.631 μm. The batch flotation results indicated that the copper oxide flotation recovery increased from 79.67% to 83.38%, and the grade also raised from 18.08% to 18.14% after using the staged flotation technology with ZH-1 as collector during the flotation of −25 μm ore. It was confirmed that this technology was quite effective for the recovery of copper oxide at the Dishui Copper Processing Plant, which successfully increased its gross profit by 1.6 million US$ per year.

Heat Transfer Models of Moving Packed-Bed Particle-to-SCO2 Heat Exchangers

2017 ◽  
Author(s):  
Kevin J. Albrecht ◽  
Clifford K. Ho
Keyword(s):  
Heat Transfer ◽  
Particle Size ◽  
Residence Time ◽  
Heat Exchangers ◽  
High Efficiency ◽  
Operating Temperature ◽  
Constitutive Relations ◽  
Packed Bed ◽  
Working Fluid ◽  
Trade Offs

Particle-based concentrating solar power (CSP) plants have been proposed to increase operating temperature for integration with higher efficiency power cycles using supercritical carbon dioxide (sCO2). The majority of research to date has focused on the development of high-efficiency and high-temperature particle solar thermal receivers. However, system realization will require the design of a particle/sCO2 heat exchanger as well for delivering thermal energy to the power-cycle working fluid. Recent work has identified moving packed-bed heat exchangers as low-cost alternatives to fluidized-bed heat exchangers, which require additional pumps to fluidize the particles and recuperators to capture the lost heat. However, the reduced heat transfer between the particles and the walls of moving packed-bed heat exchangers, compared to fluidized beds, causes concern with adequately sizing components to meet the thermal duty. Models of moving packed-bed heat exchangers are not currently capable of exploring the design trade-offs in particle size, operating temperature, and residence time. The present work provides a predictive numerical model based on literature correlations capable of designing moving packed-bed heat exchangers as well as investigating the effects of particle size, operating temperature, and particle velocity (residence time). Furthermore, the development of a reliable design tool for moving packed-bed heat exchangers must be validated by predicting experimental results in the operating regime of interest. An experimental system is designed to provide the data necessary for model validation and/or to identify where deficiencies or new constitutive relations are needed.

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