• Title/Summary/Keyword: particle size control

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A Study on Desulfurization Efficiency of Limestone Sludge with Particle Size (석회석 슬러지의 입도제어에 따른 배연탈황효율에 관한 연구)

  • Seo, Sung Kwan;Chu, Yong Sik;Shim, Kwang Bo
    • Resources Recycling
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    • v.24 no.6
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    • pp.17-23
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    • 2015
  • Flue gas desulfurization(FGD) is the technique to remove $SO_2$ gas from stack gases of coal-fired plants. Many researcher have studied to replace the desulfurizing agent because FGD systems use a lot of limestone and energy. In this study, we use the limestone sludge which is a by-product of steel industry in order to replace desulfurizing agent of FGD system by control the particle size of limestone sludge. And desulfurization performance test is implemented by investigating $SO_2$ gas removal properties upon the characteristic of the limestone sludge with various particle size.

Effects of Particle Size of Fly Ash on the High Strength of Hardened Cement Mortar (시멘트 모르터 경화체의 고강도화에 미치는 플라이 애쉬 입자크기의 영향)

  • 김영수;김정환
    • Magazine of the Korea Concrete Institute
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    • v.6 no.5
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    • pp.131-139
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    • 1994
  • The min aim of thls study was to evaluate the effect of particle slze of the fly ash as a cement additive. Experimental work was carried out with three different sizes of fly ash. 18.58, 8.95 and 4.02{$mu}m$ in average radius. Namely, the effect of particle size variation of fly ash on the physical properties of cement paste was investigated. The jluidity was decreased with increasing the addition of fly ash to cement paste regardless of the particle size variation. The decrement of the fluidity of the pulverized fly ash was higher than that of the spherical fly ash. On the other hand, the pozzolan reactivity increased with lowering particle size. In the case of specimens with 5% up to 10% addition of fly ash having a particle size of 4.02{$mu}m$. the compressive strength was increased as compared with the plain specimens before curing for 28 days and showed higher value above 800kg /$cm^2$ when cured for 60 days.This increased compressive strength was ascribed to both the closer packlng of fine particles and the pozzolan reactivity of fly ash. These results were comfirmed by measuring both the porosity of the specimens and Ca(OH ), contents remained in specimens. This work showed that could be effectively ut~lized as a blending material without any de crease in the strength of early hydration stage if we can control the particle size of fly ashes by sizing or pulverizing.

Preparation of BaTiO3 Powder in $BaO2-TiO2-Reduction Agent-PSCA (Particle Size Control Agent) System by SHS and Its Dielectric Properties (B3O2-TiO2-환원제-입자제어제계에서 자전연소합성법에 의한 BaTiO3분말의 제조 및 유전특성)

  • Yun, Ki-Seok;Lim, Sung-Jae;Nersisyan, Hayk;Won, Chang-Whan
    • Journal of the Korean Ceramic Society
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    • v.41 no.11
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    • pp.842-850
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    • 2004
  • We have investigated on the preparation of BaTiO$_3$ powder at the system of BaO$_2$-TiO$_2$-Reduction ag.-PSCA by SHS. C and Mg were used as reduction agent, and NaCl was used as PSCA (Particle Size Control Agent). The effects of the various reduction agent and its concentration, particle size control agent, reaction mixture mass on the product in the preparation of BaTiO$_3$ powder at the optimum system by SHS were investigated. The optimum conditions for reaction system and composition were BaO$_2$+TiO$_2$+0.11 Mg +0.2C+0.75NaCl in the As atmosphere. NaCl as PSCA showed the effect of controlling the particle size of product as well as the combustion temperature. The particle size of BaTiO$_3$ synthesized at the optimum condition was about 0.5 ${\mu}{\textrm}{m}$. And as the mixture mass for the reaction was increased, the more stable combustion wave appeared. We have conducted the sintering experiment at the temperature of 130$0^{\circ}C$, the time of 2 h and the atmosphere of air to measure the dielectric properties of BaTiO$_3$ synthesised in this work, and the sample sintered in this condition showed 2,290 of dielectric constant at 10$0^{\circ}C$ and 13,890 at curie point (129$^{\circ}C$).

Effect of Process-Control Agents on Characteristics of Amorphous Al-Y-Ni-Co Alloy Powder Produced by Mechanical Alloying

  • Nguyen, H.V.;Kim, J.C.;Kim, J.S.;Kwon, Y.J.;Kwon, Y.S.
    • Journal of Powder Materials
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    • v.17 no.1
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    • pp.7-12
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    • 2010
  • In this work, effect of various process-control agents (PCAs) on the mechanical alloying of amorphous alloy of $Al_{85}Y_8Ni_5Co_2$ has been investigated. The dependence of the particle shape, size and crystallization behavior of the amorphous alloy powders on the type of PCAs and their concentrations was investigated by using X-ray diffraction, field-emission scanning electron microscopy and differential scanning calorimetry. It was found that the additive of toluene could affect positively the amorphization and thermally induced crystallization processes, as well as the size refinement, morphology and particle-size distribution of as-milled powders in comparison with alloy obtained without PCA.

Preparation and Evaluation of Bupivacaine Microspheres by a Solvent Evaporation Method (II) (용매증발법에 의한 부피바카인 마이크로스피어의 제조 및 평가 (II))

  • 곽손혁;이시범;이종수;이병철;황성주
    • YAKHAK HOEJI
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    • v.45 no.6
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    • pp.623-633
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    • 2001
  • Various bupivacaine-loaded microspheres were prepared using poly(d,1-lactide) (PLA) and poly(d,1-lactic-co-glycolide) (PLGA) by a solvent evaporation method for the sustained release of drug. The effects of process conditions such as drug loading, polymer type and solvent type on the characteristics of microspheres were investigated. The prepared microspheres were characterized for their drug loading, size distribution, surface morphology and release kinetics. Drug loading efficiency and yield of PLGA micro- spheres were higher than those of PLA microspheres. The prepared microspheres had an average particle size below 5${\mu}{\textrm}{m}$. The particle size range of microspheres was 1.65~2.24${\mu}{\textrm}{m}$. As a result of SEM, the particle size of PLA microspheres was smaller than that of PLGA microspheres. In morphology studies, microspheres showed a spherical shape and smooth surface in all process conditions. In thermal analysis, bupivacaine-loaded microspheres showed no peaks originating from bupivacaine. This suggested that bupivacaine base was molecular-dispersed in the polymer matrix of microspheres. The release pattern of the drug from microspheres was evaluated for 96 hours. The initial burst release of bupivacaine base decreased with increasing the molecular weight of PLGA, and the drug from microspheres released slowly. In conclusion, bupivacaine-loaded microspheres were successfully prepared from poly(d,1-lactide) and poly (d,1- lactic-co-glycolide) polymers with different molecular weights allowing control of the release rate.

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An Experiment on Particle Collection and Gas Removal in a 2-Stage Electrostatic Wet Scrubber (2단 정전식 세정집진기의 집진 및 가스제거 특성)

  • Yeo, Kuk-Hyun;Yoo, Kyung-Hoon;Son, Seung-Woo;Kim, Yoon-Shin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.18 no.9
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    • pp.745-752
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    • 2006
  • DOS and NaCl aerosol particles were used to determine collection efficiencies of a 2-stage electrostatic wet scrubber with respect to particle size. The DOS and NaCl aerosols have geometric mean diameters of 0.1-3.0 urn, geometric standard deviations of $1.1{\sim}1.8$ and total number concentrations of $450{\sim}2,400\;particles/cm^3$. The tested operating variables for the electrostatic wet scrubber included air velocity and water injection rate. It was shown from the experimental results that particle collection efficiencies increased in the submicron particle size range when different polarities were applied on the water nozzle and corona wire, respectively. This increase in the collection efficiency is attributed to strong electrostatic attraction between the negative water droplets and positive submicron particles. The collection efficiencies also increased when water injection rate was increased or air velocity was decreased. Meanwhile, the pressure drop across the wet scrubber decreased by 90% compared with the existing mechanical wet scrubber. Finally, ammonia gas was used to determine gas removal efficiencies. It was observed that the gas removal efficiencies increased when the air velocity was decreased or the water injection rate was increased.

Particle Size Control by the Addition of PVA and HNO3 in γ-Al2O3 Synthesis Using by Sol-Gel Method (졸-겔법을 이용한 γ-Al2O3 합성 시 PVA와 HNO3 첨가에 따른 입자크기 제어)

  • Um, Myeong-Heon;Kim, Na-Eun;Ha, Beom-Yong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.11
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    • pp.537-543
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    • 2019
  • Alumina(Al2O3) is a ceramic material used in industry with a range of particle sizes and characteristics. In this study, a boehmite sol was prepared by a hydrolysis and peptizing process using the Sol-Gel method from aluminum isopropoxide (AIP). γ-Al2O3 was prepared by drying and calcining. To prevent particle agglomeration during the manufacturing process, four kinds of polyvinyl alcohol (PVA) with molecular weights of 9,000~10,000, 31,000~50,000, 89,000~98,000, and 130,000 were added and three concentrations of HNO3 (0.1, 0.3, 0.5 molar ratio) were added to determine their effects on the particles. The crystal structure, composition, particle size and shape of the prepared γ-Al2O3 were confirmed through x-ray diffraction (XRD), x-ray fluorescence analyzer (XRF), particle size analyzer (PSA), and field emission scanning electron microscopy (FE-SEM). As a result, γ-Al2O3 with a purity of approximately 98.2% was synthesized, and the particle size decreased and the uniformity increased with increasing ratio of HNO3 addition and PVA molecular weight. From these results, the particle size can be controlled during the manufacturing process of γ-Al2O3 by controlling the addition ratio of PVA and HNO3.

A Study on the Development of Two-phase Nozzle Suitable for Multi-purpose Spraying in Orchards (과수원 내 다목적 살포에 적합한 이류체 노즐 개발에 관한 연구)

  • Han, Kwang Ho;Kang, Tae Gyoung;Lee, Dong In;Lee, Chul-Hee
    • Journal of Drive and Control
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    • v.17 no.4
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    • pp.1-7
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    • 2020
  • In orchard or crop-growing environments, pesticides are sprayed using various nozzles to prevent pests and improve productivity. Nozzles currently in use are restricted for use in multi-purpose environments, thus, it is necessary to develop new nozzles. In this study, new two-phase nozzles are proposed to improve the performance of the nozzle (flow rate, spray angle, spray particle size). The performance of the two-phase nozzles are predicted through the CFD analysis and the performance of the nozzles is compared with the experiment. The experimental results showed that the proposed two-phase nozzles are available at relatively low operating pressure condition and are capable of extensive spray particle size control. Thus, the proposed nozzles are expected to be available in various orchard environments.

Development of Particle Deposition System for Cleaning Process Evaluation in Semiconductor Fabrication (반도체 세정 공정 평가를 위한 나노입자 안착 시스템 개발)

  • Nam, Kyung-Tag;Kim, Young-Gil;Kim, Ho-Joong;Kim, Tae-Sung
    • Journal of the Semiconductor & Display Technology
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    • v.6 no.4
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    • pp.49-52
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    • 2007
  • As the minimum feature size decrease, control of contamination by nanoparticles is getting more attention in semiconductor process. Cleaning technology which removes nanoparticles is essential to increase yield. A reference wafer on which particles with known size and number are deposited is needed to evaluate the cleaning process. We simulated particle trajectories in the chamber by using FLUENT. Charged monodisperse particles are generated using SMPS (Scanning Mobility Particle Sizer) and deposited on the wafer by electrostatic force. The Experimental results agreed with the simulation results well. We calculate the particles loss in pipe flow theoretically and compare with the experimental results.

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