• Title, Summary, Keyword: attrition

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Physical Properties and Sulfidation Kinetics of Mn-Based Sorbent for Hydrogen Sulfide Removal (황화수소 제거를 위한 망간계 탈황제의 물리적 특성과 황화반응 속도)

  • Oh, Kwang-Joong;Shon, Byung-Hyun;Choi, Eun-Hwa;Yi, Gang Woo
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.11
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    • pp.2067-2076
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    • 2000
  • The experiments have been made to develop manganese-based sorbent(MT, MFT) for the removal of hydrogen sulfide from simulated hot coal gases. Manganese-based sorbents were tested in an ambient-pressure fixed-bed reactor to calculate H2S removal efficiency. and a three hole jet attrition tester to characterize the sorbent physical properties. According to the experimental results of attrition test. the attrition resistance of 5% bentonite containing sorbent was higher than that of 2% bentonite. The attrition resistances of both sorbents increased with induration temperature. Effects of sulfidation temperature. space velocity. and $H_2S$ concentrations on the $H_2S$ removal efficiency were investigated. Experimental results showed that $H_2S$ could be removed from 5,100ppmv to 20ppmv at $450^{\circ}C$, and to 30~65ppmv at $550{\sim}650^{\circ}C$ for both MT/MFT sorbents. As for the change of space velocity, the breakthrough time was decreased with space velocity.

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The Attrition and Calcination Characteristics of Domestic Limestones for In-Situ Desulfurization in Circulating Fluidized Bed Boilers (순환유동층 로내 탈황을 위한 국내 석회석의 마모 및 소성 특성)

  • Kim, Ye Bin;Kang, Seo Yeong;Seo, Su Been;Keel, Sang In;Yun, Jin Han;Lee, See Hoon
    • Korean Chemical Engineering Research
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    • v.57 no.5
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    • pp.687-694
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    • 2019
  • In order to investigate the behavior of limestones which have been usually used for in-situ desulfurization reaction in circulating fluidized bed combustors, the attrition characteristics and calcination reactions of domestic limestones were analyzed in this study by using a thermogravimetric analyzer and an ASTM D5757-95 attrition tester. The average size distribution of limestones in circulating fluidized bed boilers have to be changed due to the attrition of particle-particle and particle-reactor wall and the calcination reaction. Domestic limestones might be used in commercial circulating fluidized bed boilers, but the attrition behaviors and particle size changes of limestones were varied. In calcination experiments at $850^{\circ}C$, the calcination reaction were varied with limestone samples. The calcination reaction time increased with an increase of particle size. Also, fine particles generated the attrition test of calcined limestone was 20% higher than those generated the attrition test of original limestone.

The Study on Attrition Resistance of ZnO/natural-zeolite/Fe$_2$O$_3$ Desulfurization Sorbents with CaO for Hot Gas Clean-up (산화칼슘이 첨가된 ZnO/Natural-zeolite/Balho Kim/Fe$_2$O$_3$ 탈황제의 내마모성특성 연구)

  • 정용길;박노국;이종대;전진혁;류시옥;이태진
    • Journal of Energy Engineering
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    • v.13 no.1
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    • pp.75-81
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    • 2004
  • ZZFCa sorbents for hot gas desulfurization in IGCC were prepared by adding calcium oxide to ZZF sorbent in order to improve its attrition resistance in this study. ASTM attrition test for the sorbent was performed at several different weight percentages of CaO to investigate the attrition characteristics of ZBFCa sorbents as a function of CaO content. Attrition index of ZZF without CaO was 28.3% and its collected attrition index was 10.8%. ZZFCa-3 containing 3 wt% CaO showed the lowest attrition index (AI=17.3%, CAI=8.8%) in the test. From the results of SEM morphologies and particle size distribution measurements, ZZFCa-3 maintained a fine shape and a desirable average particle size even after attrition test. In the experiments of sulfidation/regeneration for ZZFCa-3 sorbent concentration of hydrogen sulfide in coal gas was lowered from 10000 ppm to below 1 ppm. Sulfur removing capacity was about 28.8 g S/100 g sorbent. Neither formation of CaSO$_4$ was observed in XRD measurement nor SO$_2$ slippage was observed during sulfidation process.

Effect of Attrition Scrubbing on the Recovery of Platinum Group Metals from Spent Automobile Catalytic Converters (자동차(自動車) 폐촉매(廢觸媒)로부터 백금족(白金族) 회수(回收)를 위한 어트리션 스크러빙의 효과(效果))

  • Kim, Wan-Tae;Kim, Hyung-Seok;Cho, Sung-Baek;Lee, Jae-Chun;Kim, Sang-Bae
    • Journal of the Korean Institute of Resources Recycling
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    • v.17 no.5
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    • pp.28-36
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    • 2008
  • The effect of attrition scrubbing on the recovery of platinum group metals (PGMs) from automobile catalytic converters has been investigated. Catalytic converters were first crushed into particles less than 2 mm and attrition scrubbed in the range of 60 min, and then they were sieved with several screens. The catalyst layer, $\gamma$-alumina, was dislodged from the surface of the supporting matrix into fine particles less than $45{\mu}m$ by attrition scrubbing. The fraction of fine particles less than $45{\mu}m$ increased as the residence time for attrition scrubbing increased. The composition of the fine fraction obtained at a residence time of 40 min was $CeO_2$ 19.3%, $ZrO_2$ 1.9% and PGMs 419 ppm. In the fine fraction, the recovery of y-alumina increased proportionally to the residence time. Simultaneously, the recovery rates of $CeO_2$, $ZrO_2$ and PGMs increased to 82.9%, 78.7% and 78.9%, respectively. The production of the fine fraction less than $45{\mu}m$ and the recovery of $\gamma$-alumina increased when the solid concentration and initial feed size increased. Therefore, the attrition scrubbing as the comminution and separation process was concerned to be effective for the recovery of catalyst layer from ceramic supporting matrix by physical impact and shearing action between particles in the scrubbing vessel.

The Fabrication of Low Shrinkage, Reaction-Bonded Alumina/Zirconia Composite (저수축 반응소결 알루미나/지르코니아 복합체의 제조)

  • 박정현;김용남;김성훈;강민수;송규호
    • Journal of the Korean Ceramic Society
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    • v.37 no.3
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    • pp.211-218
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    • 2000
  • The attrition-milled powder mixtures of Al and Al2O3 were oxidized below 140$0^{\circ}C$ for 1 hr and post-sintered at 150$0^{\circ}C$ and 1$600^{\circ}C$ for 2 hr. During attrition milling, ZrO2 was added to the system by grinding effect of ZrO2 balls. The average particle size of the powder mixtures was decreased by the attrition milling as the aluminum content decrease. Above 120$0^{\circ}C$, sintering behaviro was observed on the fine Al2O3 particles resulted from the oxidation of Al. The specimens heat-treated at 140$0^{\circ}C$ for 1 hr showed the bending strength of 166 MPa and hardness of 220 MPa. The specimens post-sintered at 1$600^{\circ}C$ for 2hr had a linear shrinkage of 9~12% and a relative density of about 95%. After the post-sintering, the specimens having 55 vol% Al content revealed the bending strength of 513 MPa and hardness of 718 MPa. The Weibull modulus to the bending strength was about 16.

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Attrition Milling and Reaction-sintering of the Oxide-Metal Mixed Powders: II. Reaction-sintering Behavior as the Milling Characteristics of Powders (산화물과 금속 복합 분말의 Attrition Milling 및 반응소결: II. 분말의 분쇄특성에 따른 반응소결 거동)

  • 황규홍;김의훈
    • Journal of the Korean Ceramic Society
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    • v.31 no.4
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    • pp.448-456
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    • 1994
  • The reaction-sintered alumina and zirconia-alumina ceramics were fabricated from the Al/Al2O3 or Zl/ZrO2(Ca-PSZ) powder mixtures via the attrition milling. And the effects of the milling characteristics of used raw powders on reaction sintering were investigated. After attrition milling and isopressing at 400 MPa the Al/Al2O3 specimen was oxidated at 1200℃ for 8 hours followed by sintering at 1550℃ for 3 hours. Because mixed powders of flake-type Al with coarse alumina was much more effectively comminuted than the globular-type Al with coarse alumina powders, it's sintered body of more than 97% theoretical density was achived, but low contents of Al leads to relatively higher shrinkage of about 8%. And because coarse alumina particles was much more beneficial in cutting and reducing the ductile Al particles, using the coarse alumina powder was much more effective in reaction sintering. Fused Ca-PSZ powder was reaction sintered with Al at 1550℃ for 3 hours and low shrinkage ZrO2-Al2O3 composites were fabricated. But because Al/Ca-PSZ powder mixtures were not effectively milled the reaction sintering and densification was difficult. And the Ca ion in Ca-PSZ grains diffused into alumina grains during sintering so that the unstabilization of Ca-PSZ body was occured which gave the microcracks in the specimens.

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