• Title/Summary/Keyword: Slurry method

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Numerical and Experimental Study on the Coal Reaction in an Entrained Flow Gasifier (습식분류층 석탄가스화기 수치해석 및 실험적 연구)

  • Kim, Hey-Suk;Choi, Seung-Hee;Hwang, Min-Jung;Song, Woo-Young;Shin, Mi-Soo;Jang, Dong-Soon;Yun, Sang-June;Choi, Young-Chan;Lee, Gae-Goo
    • Journal of Korean Society of Environmental Engineers
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    • v.32 no.2
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    • pp.165-174
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    • 2010
  • The numerical modeling of a coal gasification reaction occurring in an entrained flow coal gasifier is presented in this study. The purposes of this study are to develop a reliable evaluation method of coal gasifier not only for the basic design but also further system operation optimization using a CFD(Computational Fluid Dynamics) method. The coal gasification reaction consists of a series of reaction processes such as water evaporation, coal devolatilization, heterogeneous char reactions, and coal-off gaseous reaction in two-phase, turbulent and radiation participating media. Both numerical and experimental studies are made for the 1.0 ton/day entrained flow coal gasifier installed in the Korea Institute of Energy Research (KIER). The comprehensive computer program in this study is made basically using commercial CFD program by implementing several subroutines necessary for gasification process, which include Eddy-Breakup model together with the harmonic mean approach for turbulent reaction. Further Lagrangian approach in particle trajectory is adopted with the consideration of turbulent effect caused by the non-linearity of drag force, etc. The program developed is successfully evaluated against experimental data such as profiles of temperature and gaseous species concentration together with the cold gas efficiency. Further intensive investigation has been made in terms of the size distribution of pulverized coal particle, the slurry concentration, and the design parameters of gasifier. These parameters considered in this study are compared and evaluated each other through the calculated syngas production rate and cold gas efficiency, appearing to directly affect gasification performance. Considering the complexity of entrained coal gasification, even if the results of this study looks physically reasonable and consistent in parametric study, more efforts of elaborating modeling together with the systematic evaluation against experimental data are necessary for the development of an reliable design tool using CFD method.

Effects of chromium chloride addition on coloration and mechanical properties of 3Y-TZP (크롬염화물 첨가에 따른 지르코니아 색상 및 물리적 성질 변화에 관한 연구)

  • Oh, Gye-Jeong;Seo, Yoon-Jeong;Yun, Kwi-Dug;Lim, Hyun-Pil;Park, Sang-Won;Lee, Kyung-Ku;Lim, Tae-Kwan;Lee, Doh-Jae
    • The Journal of Korean Academy of Prosthodontics
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    • v.49 no.2
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    • pp.120-127
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    • 2011
  • Purpose: The purpose of this study was to examine the effects of chromium chloride addition on coloration, mechanical property and microstructure of 3Y-TZP. Materials and methods: Chromium chloride was weighed as 0.06, 0.12, and 0.25 wt% and each measured amount was dissolved in alcohol. $ZrO_2$ powder was mixed with each of the individual slurry to prepare chromium doped zirconia specimen. The color, physical properties and microstructure were observed after the zirconia specimen were sintered at $1450^{\circ}C$. In order to evaluate the color, spectrophotometer was used to analyze the value of $L^*$, $C^*$, $a^*$ and $b^*$, after placing the specimen on a white plate, and measured according to the International Commission on Illumination (CIE) standard, Illuminant D65 and SCE system. The density was measured in the Archimedes method, while microstructures were evaluated by using the scanning electron microscopy (SEM) and XRD. Fracture toughness was calculated Vickers indentation method and indentation size was measured by using the optical microscope. The data were analyzed with 1-way ANOVA test (${\alpha}$ = 0.05). The Tukey multiple comparison test was used for post hocanalysis. Results: 1. Chromium chloride rendered zirconia a brownish color. While chromium chloride content was increased, the color of zirconia was changed from brownish to brownish-red. 2. Chromium chloride content was increased; density of the specimen was decreased. 3. More chromium chloride in the ratio showed increase size of grains. 4. But the addition of chromium chloride did not affect the crystal phase of zirconia, and all specimens showed tetragonal phase. 5. The chromium chloride in zirconia did not showed statistically significant difference in fracture toughness, but addition of 0.25 wt% showed a statistically significant difference (P<.05). Conclusion: Based on the above results, this study suggests that chromium chlorides can make colored zirconia while adding in a liquid form. The new colored zirconia showed a slight difference in color to that of the natural tooth, nevertheless this material can be used as an all ceramic core material.

Mineralogical and Physical Properties of Lime Plaster used in Wall Repair in Temple of Bagan, Myanmar (미얀마 바간지역 사원 벽체 보수에 사용되는 석회 플라스터의 광물학적 및 물리적 특성)

  • Ahn, Sunah;Kim, Eunkyung;Nam, Byeongjik;Hlaing, Chaw Su Su;Kang, Soyeong
    • Journal of the Mineralogical Society of Korea
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    • v.31 no.4
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    • pp.267-275
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    • 2018
  • The purposes of this study were to analyze the mineralogical characteristics of slaked lime used for wall repair of traditional buildings in Bagan, Myanmar and to evaluate the physical properties of lime plaster produced by the same method as Bagan region. In the X-ray diffraction and thermal analysis of the Myanmar slaked lime, portlandite ($Ca(OH)_2$) and brucite ($Mg(OH)_2$) were detected as main constituent minerals, and a carbonate rock mainly composed of dolomite ($CaMg(CO_3)_2$) minerals may be used as a raw material to make slaked lime. The field-emission scanning electron microscope analysis showed that the Myanmar slaked lime was composed of irregularly shaped crystals of $0.5{\mu}m$ or larger and a small amount of $0.1{\mu}m$ of plate - like crystals. The size and uniformity of crystals in Myanmar lime is different from that of Korea slaked lime. This may be attributed to the effect of the mineral composition and the lime hydration method of Myanmar, which produces slurry by immersing the burnt lime in excess water for a long period of time. The compressive strength of the lime plaster in Myanmar resulted in a mean value of $1.13N/mm^2$ for the specimens cured for 28 days. The strength of the specimens with Bale juice was $1.03N/mm^2$, respectively. The lime is an air setting material that exhibits strength through long carbonation process. Therefore, it is necessary to evaluate physical properties according to curing period through long-term curing over 28 days in the future.

Optimization for Ammonia Decomposition over Ruthenium Alumina Catalyst Coated on Metallic Monolith Using Response Surface Methodology (반응표면분석법을 이용한 루테늄 알루미나 메탈모노리스 코팅촉매의 암모니아 분해 최적화)

  • Choi, Jae Hyung;Lee, Sung-Chan;Lee, Junhyeok;Kim, Gyeong-Min;Lim, Dong-Ha
    • Clean Technology
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    • v.28 no.3
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    • pp.218-226
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    • 2022
  • As a result of the recent social transformation towards a hydrogen economy and carbon-neutrality, the demands for hydrogen energy have been increasing rapidly worldwide. As such, eco-friendly hydrogen production technologies that do not produce carbon dioxide (CO2) emissions are being focused on. Among them, ammonia (NH3) is an economical hydrogen carrier that can easily produce hydrogen (H2). In this study, Ru/Al2O3 catalyst coated onmetallic monolith for hydrogen production from ammonia was prepared by a dip-coating method using a catalyst slurry mixture composed of Ru/Al2O3 catalyst, inorganic binder (alumina sol) and organic binder (methyl cellulose). At the optimized 1:1:0.1 weight ratio of catalyst/inorganic binder/organic binder, the amount of catalyst coated on the metallic monolith after one cycle coating was about 61.6 g L-1. The uniform thickness (about 42 ㎛) and crystal structure of the catalyst coated on the metallic monolith surface were confirmed through scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. Also, a numerical optimization regression equation for NH3 conversion according to the independent variables of reaction temperature (400-600 ℃) and gas hourly space velocity (1,000-5,000 h-1) was calculated by response surface methodology (RSM). This model indicated a determination coefficient (R2) of 0.991 and had statistically significant predictors. This regression model could contribute to the commercial process design of hydrogen production by ammonia decomposition.

Comparison of the Effectiveness of Oral Doxycycline, Homologous Blood and Talc as Pleural Sclerosing Agents in Rats (쥐에시 경구 독시사이클린, 동종 혈액, 탈크의 흉막 유착에 대한 비교)

  • Kang, Shin-Kwang;Won, Tae-Hee;Kim, Si-Wook;Na, Myung-Hoon;Yu, Jae-Hyun;Lim, Seung-Pyung;Lee, Young;Kang, Dae-Young
    • Journal of Chest Surgery
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    • v.36 no.10
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    • pp.721-727
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    • 2003
  • Background: Parenteral tetracycline is no longer available for pleural sclerosing agent for pleurodesis in Korea due to the discontinuation of the production. The purposes of this study were to determine whether oral doxycycline (ODC) could be used as an effective sclerosing agent for pleurodesis, and to compare the effectiveness of ODC to other agents, such as homologous blood and talc. Material and Method: Twenty male rats were divided into four groups (A to D). Following agents were given to each group intrapleurally; 10 $m\ell$/kg of 0.9% saline to group A, 10 mg/kg of ODC to group B, 2 $m\ell$/kg of homologous blood to group e, and 70 mg/kg of talc slurry to group D. All animals were sacrificed 28 days after instillation. The pleural spaces were assessed grossly and microscopically and were graded from 0 to 3, and the thicknesses of the pleura were measured. Result: The gross score of group A was 0.0, group B was 1.4$\pm$0.9, group e was 1.0$\pm$0.7, and group D was 2.2$\pm$0.8. Significant adhesion were examined in group B and D grossly (p < 0.05). The pleural thickness of group A was 0.7$\pm$0.2 /10$^2$ mm, group B was 1.2$\pm$0.4 /10$^2$ mm, group C was 1.4$\pm$0.4 /10$^2$ mm, and group D was 3.5$\pm$0.9 /10$^2$ mm. Group D showed pleural thickening significantly (p < 0.05). The microscopic score of group A was 1.0, group B was 1.7$\pm$0.5, group e was $1.5\pm$0.4, and group D was 2.8$\pm$0.4. Group B and D showed significant inflammations and depositions of collagen (p < 0.05). Conclusion: ODC showed significant pleurodesis grossly and microscopically, and homologous blood did not show adhesion. Talc was a significant sclerosing agent for pleurodesis causing extensive inflammation and collagen depisotion.

Video-assisted Talc Poudrage for the Treatment of Malignant Pleural Effusion: Analysis of Effects and Benefits (악성 늑막 삼출증에서의 비디오 흉강경하 탈크 분무의 효과 및 장점 분석)

  • Song, In-Hag;Chang, Won-Ho;Choi, Chang-Woo;Son, Jin-Sung;Kim, Dong-Hyun;Baek, Kang-Seok;Youm, Wook;Kim, Hyun-Jo
    • Journal of Chest Surgery
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    • v.40 no.7 s.276
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    • pp.492-498
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    • 2007
  • Background: Malignant pleural effusion is a common condition in neoplastic patients and palliative therapy is the usual treatment. Talc has been generally accepted to be the most effective sclerosant for chemical pleurodesis, but the optimal route of administration remains controversy. We compared the results of video-assisted thoracoscopic talc poudrage (VTP) with administering a bedside talc slurry through a chest tube (BTS) for the treatment of malignant pleural effusion. Material and Method: From December 2004 to May 2006, 20 patients with malignant pleural effusion underwent chemical pleurodesis via VTP (group A, n=10), and BTS (group B, n=10). Result: The durations of chest tube placement after the procedure were $7.0{\pm}4.0$ days (group A) and $6.7{\pm}3.6$ days (group B). The hospital stays were $24.3{\pm}9.4$ days (group A) and $30.7{\pm}21.5$ days (group B), respectively. The symptoms of dyspnea were much more improved in group A (p-value=0.014) after discharge (mean f/u group $A=8.5{\pm}2.2$ months, group B $8.0{\pm}7.4$ months). The collapsed portions of lung were better expanded in group A than in group B (p-value=0.011). Conclusion: We recommend VTP for the selected patients with malignant pleural effusion because of the advantages of dissecting the fibrous peel to relieve the atelectasis and dyspnea, and excising the pleura for diagnosis with direct viewing of the lesion.

EVALUATION ON THE ABRASION RESISTANCE OF A SURFACE SEALANT (레진전색제의 마모저항성에 대한 평가)

  • Kim, Soo-Mee;Han, Sae-Hee;Cho, Young-Gon
    • Restorative Dentistry and Endodontics
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    • v.32 no.3
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    • pp.180-190
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    • 2007
  • The purpose of this study was to evaluate the abrasion resistance of surface penetrating sealant which was applied on a composite resin restoration and to provide proper time to reapply sealant on composite resin surface. Two hundred rectangular specimens, sized $8\times3\times2mm$, were made of Micronew (Bisco, Inc., Schaumburg, IL, U.S.A) and divided into two groups; F group (n = 10) was finished with coarse and medium grit of Sof-Lex discs and BisCoverwas applied B group (n = 190) after finishing with discs. B group was again subdivided into nineteen subgroups From B-1 group to B-18 group were subjected to toothbrush abrasion test using a distilled water-dentifrice slurry and toothbrush heads B-IM group was not subjected to toothbrush abrasion test. Average surface roughness (Ra) of each group was calculated using a surface roughness tester (Surfcorder MSE-1700: Kosaka Laboratory Ltd., Tokyo, Japan) . A representative specimen of each group was examined by FE-SEM (S-4700: Hitachi High Technologies Co., Tokyo, Japan). The data were analysed using cluster analysis, paired t-test, and repeated measure ANOVA. The results of this study were as follows; 1. Ra off group was $0.898{\pm}0.145{\mu}m$ and B-IM group was $0.289{\pm}0.142{\mu}m$. Ra became higher from B-1 group $(0.299{\pm}0.48{\mu}m$ to B-18 group $(0.642{\pm}0.313{\mu}m$. 2. Final cluster center of Ra was $0.361{\mu}m$ in cluster 1 $(B-IM\simB-7)$, $0.511{\mu}m$ in cluster 2 $(B-8\simB-14)$ and $0.624{\mu}m$ in cluster 3 ($(B-15\simB-18)$. There were significant difference among Ra of three clusters. 3 Ra of B-IM group was decreased 210.72% than Ra of F group. Ra of B-8 group and B-15 group was increased 35.49% and 51.35% respectively than Ra of B-IM group. 4. On FE-SEM, B-IM group showed the smoothest resin surface. B-8 group and B-15 group showed vertically shallow scratches , and wide and irregular vertical scratches on composite resin surface respectively. Within a limitation of this study, finished resin surface will be again smooth and glazy if BisCover would be reapplied within 8 to 14 months after applying to resin surface.

Study of the Sludge Formation Mechanism in Advanced Packaging Process and Prevention Method for the Sludge (어드밴스드 패키징 공정에서 발생할 수 있는 슬러지의 인자 확인 및 형성 방지법의 제안)

  • Jiwon Kim;Suk Jekal;Ha-Yeong Kim;Min Sang Kim;Dong Hyun Kim;Chan-Gyo Kim;Yeon-Ryong Chu;Neunghi Lee;Chang-Min Yoon
    • Journal of the Korea Organic Resources Recycling Association
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    • v.31 no.1
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    • pp.35-45
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    • 2023
  • In this study, the sludge formation in the wastewater drain from the advanced packaging process mechanisms are revealed as well as the key factors, materials, and sludge prevention methods using surfactant. Compared with that of conventional packaging process, advanced packaging process employ similar process to the semiconductor fabrication process, and thus many processes may generate wastewater. In specific, a large amount of wastewater may generate during the carrier wafer bonding, photo, development, and carrier wafer debonding processes. In order to identify the key factors for the formation of sludge during the advanced packaging process, six types of chemicals including bonding glue, HMDS, photoresist (PR), PR developer, debonding cleaner, and water are utilized and mixing evaluation is assessed. As a result, it is confirmed that the black solid sludge is formed, which is originated by the sludge seed formation by hydrolysis/dehydration reaction of HMDS and sludge growth via hydrophobic-hydrophobic binding with sludge seed and PR. For the sludge prevention investigation, three surfactants of CTAB, PEG, and shampoo are mixed with the key materials of sludge, and it is confirmed that the sludge formations are successfully suppressed. The underlying mechanism behind the sludge formation is that the carbon tails of the surfactant bind to PR with hydrophobic-hydrophobic interaction and inhibit the reaction with HMDS-based slurry seeds to prevent the sludge formation. In this regard, it is expected that various problems like clogging in drains and pipes during the advanced packaging process may effectively solve by the injection of surfactants into the drains.