• Transactions of the Korean hydrogen and new energy society
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• v.26 no.4
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• pp.357-362
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• 2015

There is potential method to utilize the liquid carbon dioxide ($LCO_2$) in coal gasification plants. The $LCO_2$ could be used to effectively transport coal particles instead of conventional carrier such as liquid water ($H_2O$) particularly in wet-fed gasifier. However, there is a lack of fundamental study on the atomization behavior of $LCO_2$ coal slurry under high pressure condition. In this study, the flashing spray characteristics of a coal mixture with $LCO_2$ was examined during a throttling process by using a flow visualization system. The spray of coal water slurry which is in the Rayleigh-type break up mode was significantly different. This difference indicates that the coal water slurry did not effectively transport the coal, as compared to $LCO_2$ coal slurry.

• Journal of the Korea Concrete Institute
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• v.21 no.1
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• pp.3-11
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• 2009

The increased demand and consumption of coal has intensified problems associated with disposal of solid waste generated in utilization of coal. Major utilization of coal by-products has been in construction-related applications. Since fly ash accounts for the part of the production of utility waste, the majority of scientific investigations have focused on its utilization in a multitude of use, while little attention has been directed to the use of bottom ash. As a consequence of this neglect, a large amount of bottom ash has been stockpiled. However, the need to obtain safe and economical solution for its proper utilization has been more urgent. The study presented herein is designed to ascertain the performance characteristics of bottom ash, as autoclaved lightweight foamed concrete product. The laboratory test results indicated that tobermorite was generated when bottom ash was used as materials for hydro-thermal reaction. According to the analysis of variance, at the fresh state, water ratio affects on flow and slurry density of autoclaved lightweight foamed concrete, but foam ratio influences on slurry density, while, at the hardened state, foam ratio affects on the density of dry and the compressive strength but doesn't affect on flexural and tensile strength. In the results of response surface analysis, to obtain target performance, the most suitable mix condition for lightweight foamed concrete using bottom ash was water ratio of 70$\sim$80% and foaming ratio of 90$\sim$100%.

• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.129-139
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• 2010

Coal gasification process, which had developed originally to convert coal from hydrogen and carbon monoxide, has used and developed in many countries because of environmental advantages such as carbon dioxide storage, decrease of pollutants and so on. Generally entrained-flow gasification process using pulverized coal under $75{\mu}m$ is used in Integrated Gas Combined Cycle(IGCC) because of easy scale up and high efficiency of energy conversion. Especially entrained-flow gasifers with coal water slurry have been used in many applications due to its fully developed technologies. In this paper, several technologies for coal-water slurry gasification that involves slurry preparation, burner, gasifier, slag melting and numerical simulation for plant design and operation were investigated. Entrained-flow gasification with coal water slurry can be used for synfuel production, SNG, chemicals as well as IGCC. To develop hybrid gasification process and use different types of coal, it is necessary to develop new technologies that will increase efficiency of the process.

• Resources Recycling
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• v.4 no.1
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• pp.20-24
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• 1995

When the slurry of water and coal which is produced from hydraulic coal mining was dehydrated by COM(Coal Oil Mixtue), the effects of flocculant were measured by light transmittance of supernatant liquid, The experimental results obtamed m this study are summarized as follows; The efficient flocculant is anionic flocculant(AllO), and in this case, the required concentration is about l00g/t. When diesel oil is used with flocculant, COM is formed in lower impeller speed than when only diesel oil is used. The amout of diesel oil required to form COM is 10% of that of coal.

• Journal of Energy Engineering
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• v.6 no.1
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• pp.96-103
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• 1997

Coal gasification experiments were performed to characterize the bench scaled unit of 0.5∼1.0 T/D entrained coal gasifier developed by KIER. Datong coal from China was selected for this study. The system was operated at the temperature range of 1300∼1550$^{\circ}C$, with 62.5% of coal water mixture on the basis of dry coal. Oxygen and slurry mixture were preheated prior to feeding into burner and the ratio of oxygen/coal was in the range of 0.8∼1.2. In the preparation of coal water mixture, 0.3 wt% of CWM1002 and 0.05 wt% of NaOH wire added to reduce viscosity as well as to enhance theological properties of slurry. The resultant gaseous products consist primarily of hydrogen, carbon monoxide, carbon dioxide, and minor amounts of methane. Formation of H$_2$and CO was increased, while CO$_2$was decreased as the reacting temperature being increased due to the char-CO$_2$reaction. Maximum production of H$_2$and CO occurred in the O$_2$/coal ratio of 0.9 at 1530$^{\circ}C$. Heating values of product gases were in the range of 1700∼2400 kcal/N㎥.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.76.2-76.2
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• 2011

석탄으로부터 합성석유를 생산하는 상용기술을 도입하여 건설하고 이와 더불어 원천기술 개발을 위한 국산화 기술 개발을 병행하여 향후 고유가 시대를 대비한 국가 에너지 안보 확립과 국내 기술 개발의 가속화를 추구해야 할 필요성이 대두되고 있다. 본 타당성 조사는 3종류의 석탄(호주 Wyong탄, 인도네시아 NTC탄, 인도네시아 KBB탄)으로부터 가스화에 의하여 합성석유스를 생산하는 공정에 대한 타당성 조사(Feasibility Study, FS)를 Class 5(하한 -50~-20%, 상한 30~100%)의 정확도로 수행하는 것을 내용으로 하고 있다. 플랜트의 규모는 합성석유 기준으로 20,000배럴/일이다. 플랜트의 건설을 위해서 광양제철소 슬래그처리장 내 12만평 부지에 조성 중인 포스코 SNG 생산공장 부지의 일부를 사용하는 것을 기준으로 하였다. 일반적으로 석탄의 종류에 따라서 가스화기의 종류 및 성능이 결정된다. 본 타당성 조사 연구에서 선정된 3종류의 석탄의 조성, 발열량, 회분 함량 등의 특성을 고려하여 각각의 석탄에 적합한 현존하는 상용급 가스화기를 선정하였다. 해당 석탄이 가스화기 종류에 따라 적절한 전처리 과정(건조, 분쇄, 슬러리화)을 거친 후 가스화기에 공급되는 것을 가정하여 석탄의 원소분석 조성, 발열량, 회분함량, 회분조성, 회 용융점 등의 변수에 따라서 각각 해당 가스화기에서 가스화되었을 때의 생성되는 합성가스의 조건을 시뮬레이션을 통하여 얻었다. 가스화기 시뮬레이션 결과를 토대로 합성석유 및 합성천연가스 생산을 위한 공정의 물질수지식 및 에너지수지식이 계산되었으며 이로부터 각 공정에서 발생되는 부생성물과 폐기물에 대한 양이 결정되고 이를 처리하는 방안 등도 제시되었다. 실증시설은 20,000배럴/일 규모의 CTL 및 전기 병산 시설이 적합하다. 더 큰 규모 공장은 투자비가 너무 커서 유가 또는 석탄가 변동에 따라 사업의 수익성이 크게 변하여 위험도가 큰 단점이 있기 때문이다. CTL 공장에 전기 병산이 추천되는 이유는 산소생산공장(APU), 압축 등 석탄전환공장에는 자체적인 전기수요가 막대하여 따로 스팀터빈용 발전소를 운영하므로 이를 효율적으로 대체하고자 하기 때문이다. 즉, 석탄가스화에 의해 기름을 최대한 만들고 미반응가스는 가스터빈 및 스팀터빈의 복합발전에 의해 고효율로 전기를 생산하면 최소의 비용으로 최대한 전기를 생산하여 자체소비 전력을 충당하고 남는 전기는 판매하여 수익률을 높일 수 있다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.453-456
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• 2007

감압 증류 후 생성되는 중질유의 고도화를 위하여 코킹 공정을 거친 후 정유 부산물로 생성되는 열적으로 매우 안정하고, 높은 발열량을 갖는 반면 황, 바나듐 함량이 높은 석유코크스의 효과적인 이용을 위하여 본 연구에서는 가스화 공정을 적용하였다. 1T/D 용량의 분류층 가스화기를 이용하여 유연탄(drayton coal), 석유코크스, 또는 혼합한 경우의 가스화 성능을 알아보았으며, 각각의 경우에 대하여 비교하여 보았다. 높은 열 안정성을 갖는 석유코크스의 효과적인 가스화를 위하여 반응기 내 체류시간 및 버너 노즐 변경에 따른 가스화 성능 개선을 시도하였으며, 이때의 온도, 산소/원료 공급량 조건에 따른 생성가스 성분 및 탄소전환율, 냉가스효율 변화 특성을 알아보았다. 버너 노즐 구경 변경으로 인한 슬러리의 미립화를 통하여 향상된 탄소전환율 및 냉가스효율을 얻을 수 있었다.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.5
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• pp.451-460
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• 2013

In a direct coal fuel cell (DCFC) system, it is essential to identify volume fraction of coal suspended in electrolyte melt in order to control its dispersion and fluidity. This requirement is compelling especially at anode channel where hot slurry is likely to flow at low velocity. In this study, light scattering techniques were employed to measure the volume fraction for a pulverized coal suspension with relatively high absorption coefficient. The particle size, scattering angle, and volume fraction were varied to evaluate their effects on the scattering behavior as well as scattering regime. The larger coal size and smaller forward scattering angle could provide a shift to more favorable scattering regime, i.e., independent scattering, where interferences of light scattering from one particle with others are suppressed.

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.561-566
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• 2008

Gasification plant using petroleum coke for refinery and power generation process is increased from considering petroleum coke as a valuable fuel. In this study, gasification of petroleum coke was performed to utilize petroleum coke and to develop essential technology using 1T/D coal gasification system. In case of petroleum coke gasification, because of lower reactivity, consumption of oxygen is higher than coal gasification. The calorific value of syngas from petroleum coke mixed with coal at a mass ratio of 1:1 shows about $6.7{\sim}7.2MJ/Nm^3$. Although carbon conversion could reach more than 92% according to oxygen amount, cold gas efficiency shows lower value than the case of coal. Therefore, it was shown that complemental study in burner design to atomize slurry droplet is required to elevate gasification performance of petroleum coke which has lower reactivity than coal.

• Journal of the Korean Geotechnical Society
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• v.29 no.1
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• pp.39-47
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• 2013

With the increase in the application of CLSM using coal ash, we performed a basic research on CLSM material, laying focus on the correlation between compressive strength and unit weight of lightweight foamed CLSM. The unconfined compression strength is a criterion for the judgment of the possibility of re-excavation and an important factor determining the economy, efficiency, and excavation character. However, to know the quantitative compression strength value takes a certain amount of time, because the applicability of unconfined compression strength of CLSM is judged by the standard of 28days. Therefore, in this study the relation between compressive strength and unit weight (foam slurry unit weight, apparent unit weight) is analyzed focusing on lightweight foamed CLSM. We also suggested a formula which can easily predict the 28-day compressive strength only using unit weight value without the need to cure the slurry for 28 days.