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결정슬래그의 T<sub>cv</sub> 측정 시 실험변수에 따른 영향
김유나(Kim, Yu-Na),오명숙(Oh, Myong-Sook S.) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.10
For crystalline slags, of which the viscosity rapidly increases at T_{cv} due to the formation of crystalline phases, the Tcv is affected by measurement conditions. In this study, we investigated the effect of cooling rate, and alumina dissolution on the determination of T_{cv}. Using synthetic slag samples based on the composition of Alaska Usibelli slag, T_{cv} were determined under a constant cooling rate of 2?C/min, and under rapid cooling with holding time to allow the slag to reach thermal and rheological equilibrium. The effect of alumina dissolution was investigated using platinum lined crucibles. The constant cooling resulted in lower T_{cv} by 33?C as compared to the equilibrium measurements. Under 2?C/min cooling, the blocking alumina dissolution resulted in lower T_{cv} by 23?C. When the T_{cv} was measured under 2?C/min cooling using an alumina crucible, therefore, the effects of a constant cooling is somewhat offset by the alumina dissolution effect, and bring the measured value closer to the true value.
석유코크스와 혼합된 국내무연탄과 수입유연탄 슬래그의 특성 규명
김민경(Kim, Min-Kyung),오명숙(Oh, Myong-Sook S.) 한국신재생에너지학회 2008 한국신재생에너지학회 학술대회논문집 Vol.2008 No.10
The vanadium rich ash of petroleum coke can give a slagging problem during because of the high melting point of V₂O₃. 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 V₂O₃ 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.