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플라이애시와 슬래그 혼합 알칼리 활성 시멘트의 미세구조 특성
장정국,Jang, Jeong Gook 인천대학교 도시과학연구원 2018 도시과학 Vol.7 No.1
This study investigates microstructural characteristics of alkali-activated cements incorporating slag and fly ash. Samples were prepared with four fly ash:slag ratios, i.e., 100:0, 90:10, 70:30 and 50:50, and they were synthesized by using an alkali activator. Microstructural characteristics of the alkali-activated cements were determined by XRD, TGA, SEM, N2 gas adsorption/desorption methods, and compressive strength test. The results showed that properties of alkali-activated fly ash/slag were significantly affected by slag contents. Alkali-activated fly ash/slag with slag content of 30-50% showed higher compressive strength than ordinary Portland cement paste. An increase in slag content resulted in a denser microstructure, which composed of amorphous gel, therefore contributed to strength development of the material.
장정국,박동근,김미란 東西大學校 2001 동서논문집 Vol.7 No.-
This study was performed to provides the characteristics of flue gas producted from wood drying process. Generally, the flue gas producted from wood drying process was elutriated with a large amount of moisture and odorous compounds such as BTX and ethanol. Therefore, it is very difficult to select and design of flue gas control devices. In order to optimum design and selection of control devices, have to investigate the various parameters such as temperature, moisture contents and flow rate of flue gas. When the wood is almost dry(<10% moisture), the moisture contents of flue gas were very high (about 18.2 V/V%). It is equivalent to 320 ton/day moisture as 1100 ton wood/day induce to the drying process. The temperature of flue gas ranges from 140℃ to 150℃ in each dryer stack with exception of the input site of wood(about 110℃). Thevelocity of flue gas In each stack ranges from 1.7 to 9.7 m/sec. About 40 VOCs in the flue gas were analyzed, and the concentrations of major VOCs(ppm) were as follows respectively; benzen: 0.054∼0.052, toluene: 1.011∼2.547, ethylbenzen: 0.472∼2.023, m,p-xylene: 0.504∼3.245, styrene: 0.015∼0.148, o-xylene : 0.271∼1.097, ethanol: 11.2∼32.5, α-pinene: 0.908∼10.578, β-pinene: 0.982∼14.278.
순환유동층 석탄재의 활용 기술과 광산 채움재 관련 규격 동향
장정국,지상우,안지환 한국자원리싸이클링학회 2017 資源 리싸이클링 Vol.26 No.2
Circulating fluidized bed combustion (CFBC) ash is one of useful mineralogical resources having abundant content of free lime and anhydrite, and has a self-cementitious property. Recently, considerable interest has been gained regarding the utilization of CFBC ash, along with its use in mine backfill and reclamation. Prior to adopt the use of CFBC ash in the mine backfill technology, discussion on the technology and related specification is prerequisite in the future. This paper presents a review on studies in the emerging technology of CFBC ash utilization, and provides useful information with regard to the specifications for mine backfills utilizing CFBC ash. 순환유동층(CFBC) 보일러 방식의 석탄화력발전소에서 발생하는 석탄재는 유리 석회와 무수석고의 함량이 풍부하고 자경성을 가지는 것을 특징으로 하는 물질로서 유용하게 활용해야 할 자원 중 하나이다. 최근 CFBC 석탄재를 포함하여 석탄화력발전소 부산물을 활용한 광산 채움 기술 및 광해 관리에 대한 관심이 점차 증가하고 있는 가운데, CFBC 석탄재를 광산 채움 분야에 적용하기위해서는 기술에 대한 검토와 함께 관련 규격에 대해 향후 충분히 논의를 거쳐야 할 여지가 있다. 이를 위해, 본 논문에서는 CFBC 석탄재의 유효 활용 기술에 대한 연구동향을 소개하고, 광산 채움 분야의 활용을 위해 국외의 규격 동향을 고찰한 후 연구방향 및시사점에 대해 정리하였다.
유동층 연소로에서 유·무연탄 혼합연소시 유연탄 혼합비에 따른 연소효율 증진에 관한 연구
장정국 東西大學校 2001 동서논문집 Vol.7 No.-
Combustion characteristics of blended coal of anthracite and bituminous are investigated in a laboratory scale fluidized bed combustor (10.8㎝ ID and 170㎝ height). The dry basis higher heating values of anthracite and bituminous coal used in this study are 2810 cal/g and 6572 cal/g, respectively. The Bituminous coal which has low ash content and shrinkage characteristics in combustion process is not remained in the fluidized bed. However, the anthacite coal is able to use a bed material and accumulate in the bed. Then the bed pressure increases with operating time. In order to operate continuously, therefore, the bottom ashes have to discharge by under drain pipe. The elutriation rate of fine particle collected tends to increase with the superficial gas velocity, however, the under drain rate of bottom ash increases in fluidized bed combustion of Bituminous- Anthracite coal blend. The relative fraction of anthracite coal in the find coal blend and the fraction of combustion of fine particle in the freeboard increase with the mixing ratio of bituminous coal to blended coal, therefore, the elutriation rate of fine particle collected tends to decrease. Due to the behavior characteristics of particle in the fluidized bed, the promotion effect of combustion efficiency with mixing ratio of bituminous coal is higher than the calculated combustion efficiencies of antharacite and bituminous coal fluidized bed combustion under the same operating conditions, i.e. about 3.5 - 12.4%. The optimum mixing ratio(MR) of butuminous coal determined is around of 0.75 in this study.