• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.230-233
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• 2008

The vanadium rich ash of petroleum coke can give a slagging problem during because of the high melting point of $V_2O_3$. For continuous removal of the slag, petroleum coke is often mixed with coal, and the viscosity of the mixed slag is an important property, determining the gasification temperature. The viscosities of the mixed slag from various mixing ratios of petroleum coke and a bituminous coal were investigated. When mixed with a crystalline coal slag, $T_{cv}$ was increased at a higher the coke content in the mixed feed. When the $V_2O_3$ concentration was greater than 4.5%, it was difficult to get accurate measurements of $T_{cv}$. The SEM/EDX analyses of the cooled slag revealed that the major crystalline phase was anorthite, and $T_{cv}$ should be related to the formation temperature of anorthite. The SEM/EDX analyses also showed that, at low concentrations of vanadium, part vanadium formed a crystalline phase with Al-Si-Ca-Fe, and the rest remained in the glassy phase, suggesting that vanadium existed as a slag component at the low viscosity region. At a high concentration, vanadium forms a phase with Ca, and the Ca-V phase was separated from the slag phase, and formed a layer above the slag. FeO in petroleum coke also played an important role determining viscosity: at high temperatures, increased FeO lowered the viscosity, but as it formed a spinel phase, the depletion of FeO in the slag resulted in a higher viscosity.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.4
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• pp.117-124
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• 2009

The purpose of the study was to improve quality of high volume fly ash concrete. The study evaluated on the possibility of early quality improvement of high volume fly ash concrete with early strength gain admixture ('GA' below) developed by the preceding research. The study regarded applying naphthalene admixture ('NA' below) to mix proportion substituting FA 15 % to be plain. In the event of substituting FA 20, 25 and 30 %, the study compared engineering properties of concrete with plain by applying GA. Because of features of fresh concrete, fluidity falls down when GA is applied. Therefore, its use amount shall be increased. Only, in W/B 60 %, it was beneficial since slump loss was reduced about 35~70 mm than plain. The study could see that AE use should be increased proportionally since air content was reduced by coming from AE absorption operation of unburned coal content included in FA according to an increase in the amount of FA use. Reduction effect of bleeding could be anticipated since the amount of bleeding appeared at least in FA 20 %. Because of hardened concrete, time of setting appeared in the same level as plain when GA was applied. Therefore, it is judged that delay of setting can be reduced. In compressive strength, the study could check the same strength development as plain when GA was applied, having nothing to do with W/B and curing temperature. However, it is thought that we shall pay attention to GA use in the event of FA 30 % substitution. Freezing and melting resistance had less early value than plain. However, it is judged that there will be no problem of frost resistance since there is no a large difference between freezing and melting resistance and plain in overall. In accelerated neutralization, it was analyzed that a problem of weakening in neutralization appointed as a demerit when FA was applied in mass in proportion with GA use could be settled to some extent.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.73.1-73.1
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• 2011

석탄가스화 복합발전(IGCC) 시스템은 고온 고압으로 운전되는 가스화기에서 미분탄을 산소와 함께 가스화하여 주로 CO 및 $H_2$를 생성하고 이때 발생되는 먼지 및 황성분은 각각 집진기 및 탈황장치에서 제거되며, 석탄 회분은 고온에서 용융되어 슬래그의 형태로 배출되는 방식을 사용하고 있다. 본 연구에서는 석탄가스화 복합발전시스템 설계에 필요한 기본자료를 파악하기 위해서, 고온 고압의 운전조건에서 1일 3톤의 석탄을 처리할 수 있는 Bench Scale급 석탄가스화기를 이용하여 가스화에 사용된 원탄 및 가스화기 설비의 각 지점에서 샘플링한 고체 시료를 중심으로 열화학적 특성을 살펴보았다. 가스화 실험은 아역청탄 계열의 ABK 석탄을 대상으로 가스화기 내부의 온도와 압력을 $1400{\sim}1450^{\circ}C$, $7.5{\sim}7.6Kg/cm^2$로 유지시키면서 실시하였다. 실험에 사용된 석탄 시료의 기본적인 물성치를 조사하기 위하여 표준방법에 따라 석탄의 공업분석, 원소분석, 발열량분석 등을 실시하였다. 석탄가스화기에서 배출된 슬래그와 대상 석탄 회분의 특성을 파악하기 위해서 XRF를 이용한 회분의 성분분석, Heating Microscope를 이용한 회분의 용융점 분석, XRD를 이용한 회분과 슬래그내의 화합물의 형태 및 결정구조 파악, SEM을 이용한 슬래그의 형상 등을 분석하였다. 또한 석탄가스화기 시스템을 구성하는 각 설비의 특성을 파악하기 위해서 관련 설비의 특정 지점에서 채취한 시료의 입도분석, 원소분석, 촤 회분 무게비, 슬래그중의 잔존탄소함량, 슬래그와 슬래그로부터 제조된 용출수내의 중금속 함량분석 등을 실시하였다.

• Korean Journal of Food Science and Technology
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• v.16 no.1
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• pp.78-82
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• 1984

Effects of various drying conditions of agar gel on the physico-chemical properties of dried agar were investigated. For drying of the agar gel$(1.0{\times}1.0{\times}34.0cm)$ by means of sun drying, simple solar drying, hot-air drying ($30^{\circ}C$, control, natural convection), hot-air drying ($30^{\circ}C$, pretreatment, natural convection) and freeze drying, it took 96, 75, 67, 50 and 21 hours, respectively. The gel strengths of dried agar gel prepared by sun drying, solar drying, freeze drying and spray drying were320, 370, 270 and $360g/cm^2$, respectively and that of hot air-dried agar gel was influenced by drying temperature, pretreatment an mode of heat transfer. The gel strength, the gelation temperature and other quality index of spray-dried agar were not inferior to those of sun-dried agar, but it was not expected to be economical because of it recovery rate. In case of hot air drying, the gel strength value of agar increased as the drying rate increased. No significant differences among various products were noted in the gelation temperature, the melting temperature, the ash and $SO_3$ content.

• Applied Chemistry for Engineering
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• v.31 no.6
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• pp.688-696
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• 2020

Petroleum coke (petcoke) is widely used, next to coal, as a gasification feedstock. In gasification processes, the viscosity of the ash and the formation of crystalline phases must be understood to ensure the continuous removal of slag. This study investigates the effect of CaO and V2O3 on petcoke slag viscosity. The viscosity of the molten slag was measured in the temperature range of 1100~1600 ℃ while varying the concentration of each component. The crystalline phases formed in a cooled slag were examined. The most slag samples tested in this study exhibited crystalline slag behavior. The increased CaO concentration resulted in a lower viscosity and a lower Tcv. The viscosity behavior changed from the glassy to crystalline slag and also showed a higher Tcv as the concentration of V2O3 increases. Most slag samples showed different crystalline phases from top to bottom. Anorthites and Ca-V phases were observed in the top and middle section, while the bottom section mainly showed V2O3 and anorthite. The vanadium in the ash forms Ca-V and V-Fe phases and also remains in molten slag. A low melting Ca-V phase can contribute to lowering the viscosity.

• Resources Recycling
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• v.25 no.6
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• pp.73-81
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• 2016

Geopolymers produced from aluminosilicate materials such as metakaolin and coal ash react with alkali activators and show higher fire resistance than portland cement, due to amorphous inorganic polymer. The percentage of thermal shrinkage of geopolymers ranges from less than 0.5 % to about 3 % until $600^{\circ}C$, and reaches about 5 ~ 7 % before melting. In this study, geopolymers paste having Si/Al = 1.5 and being mixed with carbon nanofibers, silicon carbide, pyrex glass, and vermiculite, and ISO sand were studied in order to understand the compressive strength and the effects of thermal shrinkage of geopolymers. The compressive strength of geopolymers mixed by carbon nanofibers, silicon carbide, pyrex glass, or vermiculite was similar in the range from 35 to 40 MPa. The average compressive strength of a geopolymers mixed with 30 wt.% of ISO sand was lowest of 28 MPa. Thermal shrinkage of geopolymers mixed with ISO sand decreased to about 25 % of paste. This is because the aggregate particles expanded on firing and to compensate the shrinkage of paste. The densification of the geopolymer matrix and the increase of porosity by sintering at $900^{\circ}C$ were observed regardless of fillers.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.1-9
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• 1977

The purpose of this study is to complish a method of fish glue malting with residual products such as fish head and skin discarded from sea food processing. Using the skins of Alaska pollack and file fish from fillet packers, the optimum conditions of skin glue processing were investigated and physical and chemical properties of the product were also determined. The yields of Alaska pollack, Thelagra calcogramma, skin and file fish, Novodon modestus, skin to the total body weight were $4.6\%\;and\;5.0\%$ respectively. The optimum conditions for a $49.3\%$n yield Alaska pollack skin glue processing were considered the extraction of previously tinted in $0.1\%$ calcium hydroxide solution for 3 hours with the additional water as much as 3 times of sample weight at $70^{\circ}C$ for 3 hours under the controlled pH 5.0. The conditions for file fish skin glue were similar to those of Alaska pollack except the addition of five times of water to the weight of sample skin needed for extraction. The content of crude protein of Alaska pollack and file fish skin glue were $98.0\%\;and\;96.0\%$ respectively. The contents of crude ash and crude lipid were not different from that of chemical grade gelatin. Relative viscosity, melting point, gelation temperature and jelly strength of Alaska pollack skin glue marked 5.84, $21.8^{\circ}C,\;7.1^{\circ}C\;and\;10.0g$ respectively and those of file fish skin glue showed $5.79,\;25.0^{\circ}C,\;7.4^{\circ}C\;and\;11.6g$ respectively.The color and turbidity of Alaska pollack skin glue are slightly superior to those of file fish skin glue. It is supposed that the extract residue of skin glue is valuable for use the animal feeds by the results of amino acid composition. And the ratio of each amino acid content to the total amino acid of Alaska pollack and file fish skin glue is similar to that of chemical grade gelatin.