• 한국재료학회지
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• 제23권5호
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• pp.276-280
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• 2013

Coal tar is the primary feedstock of premium graphitizable carbon precursor. Coal tars are residues formed as byproducts of thermal treatments of coal. Coal tar pitches were prepared through two different heat treatment schedules and their properties were characterized. One was prepared with argon and oxidation treatment with oxygen; the other was prepared with oxygen treatment at low temperature and then argon treatment at high temperature; both used coal tar to prepare coal tar pitches. To modulate the properties, different heat treatment temperatures ($300{\sim}400^{\circ}C$) were used for the coal tar pitches. The prepared coal tar pitches were investigated to determine several properties, such as softening point, C/H ratio, coke yield, and aromaticity index. The coal tar pitches were subject to considerable changes in chemical composition that arose due to polymerization after heat treatment. Coal tar pitch showed considerable increases in softening point, C/H ratio, coke yields, and aromaticity index compared to those characteristics for coal tar. The contents of gamma resin, which consists of low molecular weight compounds in the pitches and is insoluble in toluene, showed that the degree of polymerization in the pitches was proportional to C/H ratio. Using an oxidizing atmosphere like air to prepare the pitches from coal tar was an effective way to increase the aromaticity index at relatively low temperature.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2006년도 제33회 KOSCO SYMPOSIUM 논문집
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• pp.282-292
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• 2006

Various kinds of coals are supplied for coal fired power plants as the coal market situations are fluctuated with the high prices of oil and coals over the world. The quality of coal is decreasing as coal consumption increased and some specifications of coals are out of boiler design criteria. It could make combustion troubles such as coal clogging, spontaneous combustion, coal firing in the coal handling equipments, ash slag and clinker issues, etc. This paper covers combustion troubles, issues and countermeasures in the biggest coal fired power plant in Korea.

• 대한기계학회논문집B
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• 제21권12호
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• pp.1690-1700
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• 1997

Entrained coal gasification tests with Datong coal were performed to assess the influence of oxygen/coal ration and pressure. When gasification condition in oxygen/coal ratio has changed from 0.5 to 1.0, optimal gasification condition from low pressure runs was oxygen/coal ratio of approximately 0.9 where CO was produced about 40% and H, about 20%. Under the pressure condition of 12-14 atmospheres, optimal oxygen/coal ratio value was in the region of 0.6 where CO was produced about 55% and H2about 25%. From these results, it was found that the oxygen/ coal ratio for the maximum production of CO and H, was decreasing with the increase in gasifier pressure and also, with increasing oxygen content, carbon conversion was increased. For the Chinese Datong coal, cold gas efficiency was in the range of 40-80%.

• 대한기계학회논문집B
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• 제24권2호
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• pp.270-279
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• 2000

Recently, according to increase in the requirement of electric power, a thermoelectric power plant equipped with pulverized coal combustion system is highly valued, because coal has abundant deposits and a low price compared with others. For efficient use of coal fuel, most of plant makers are studying to improve combustion performance and flame stability, and reduce pollutants emission. One of these studies is how to control the profile of particle injection and velocity dependant on coal nozzle configuration. Basically, nozzle which has mixed flow of gas and particle is required to have the balanced coal concentration at exit, but it is very difficult to obtain that by itself without help of other device. In this study, coal distribution and pressure drop in gas-solid flow are calculated by numerical method in nozzle with various shapes of venturi diffuser as a means to get even coal particle distribution. The tentative correlations of pressure drop and exit coal distribution are deduced as function of the height, length and reducing angle of venturi from the calculated results. When coal hurner nozzle is designed, these equations are very useful to optimize the shape of venturi which minimize uneven particle distribution and pressure drop within coal nozzle.

• Journal of Preventive Medicine and Public Health
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• 제30권1호
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• pp.145-155
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• 1997

Interview survey and dermatological examination have been performed to investigate the health problems of workers continuously exposed to coal-tar pitch. The phototoxicity of coal-tar pitch was confirmed by the photopatch tests for six healthy adults. The main results are followings; 1. There was no special history of allergic diseases in both the exposed and non-exposed group. 2. The frequency of the phototoxic dermatosis and the coal-tar acne in the exposed group was significantly greate.(p<0.05) than that of the control group. In the exposed group, the phototoxic dermatosis and the coal-tar acne were observed in nine workers(90%) and seven workers(70%), respectively. However, those, disease were not observed in the control group. 3. Five results(83%) were positive to the photopatch test for coal-ta. pitch 48 hours after UVA irradiation. But the lesion was subsiding 72 hours after UVA irradiation. 4. Malignant cancers were not reported among workers ever exposed to coal-tar pitch. In conclusion, it appears that workers exposed to coal-tar pitch have high risks of phototoxic dermatosis and coal-tar acne. A health policy should be provided to prevent phototoxic dermatosis among coal-tar pitch workers. More studies are required to determine malignancy.

• 한국수소및신에너지학회논문집
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• 제21권5호
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• pp.470-477
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• 2010

The IGCC (Integrated gasification combined cycle) is known for one of the highest efficiency and the lowest emitting coal fueled power generating technologies. As the core technology of this system is the gasifier to make the efficiency and the continuous operation time increase, the research about different coal's gasification has been conducted. Our research group had set-up the coal gasifier for the pilot test to study the effect of different coals-Shenhua and Adaro coal- on gasification characteristics. Gasification conditions like temperature and pressure were controlled at a fixed condition and coal feed rate was also controlled 30 kg/h to retain the constant experimental condition. Through this study we found effects of coal composition and $O_2$/coal ratio on the cold gas efficiency, carbon conversion rate. The compounds of coal like carbon and ash make the performance of gasifier change. And carbon conversion rate was decreased with reduced $O_2$/coal ratio. The optical $O_2$/coal ratio is 0.8 for the highest cold gas efficiency approximately. At those operating conditions, the higher coal has the C/H ratio, the lower syn-gas has the $H_2$/CO ratio.

• Advances in concrete construction
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• 제4권4호
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• pp.231-242
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• 2016

The major problem of a coal combustion-based power plant is that it creates large quantity of solid wastes. So, to achieve the gainful use of waste materials and to avoid other environmental problems, this study was undertaken. The quantity of coal ash by-products, particularly coal fly ash and coal bottom ash has been increasing from the coal power plants around the world. The other objective of this study was to explore the possibility of utilization of coal ash in the production of ash bricks. In 15 different mixes, Mix Designation M-1 to M-15, the varying percentages of lime and gypsum were used and sand was replaced with coal bottom ash. Further, it has been noticed that the water absorption and compressive strength of mix M-15 is 13.36% and 7.85 MPa which is better than the conventional bricks. The test results of this investigation show that the prism strength of coal ash masonry prisms was more than that of the conventional bricks.

• Geomechanics and Engineering
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• 제22권3호
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• pp.255-264
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• 2020

With the ongoing development of deep mining of coal resources, some coal mine dynamic disasters have exhibited characteristics of both coal-gas outbursts and rockbursts. Therefore, research is required on the mechanism of rockburst-outburst coupling disaster. In this study, the failure characteristics of coal-rock combination structures were investigated using lab-scale physical simulation experiments. The energy criterion of the rockburst-outburst coupling disaster was obtained, and the mechanism of the disaster induced by the gas-solid coupling instability of the coal-rock combination structure was determined. The experimental results indicate that the damage of the coal-rock structure is significantly different from that of a coal body. The influence of the coal-rock structure should be considered in the study of rockburst-outburst coupling disaster. The deformation degree of the roof is controlled by the more significant main role of the gas pressure and the difference in the strength between the rock body and the coal body. The outburst holes and spall characteristics of the coal body after the failure of the coal-rock structure are strongly affected by the difference in strength between the roof and the coal body. The research results provide an in-depth understanding of the mechanism of rockburst-outburst coupling disasters in deep mining.

• 공업화학
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• 제31권3호
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• pp.328-333
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• 2020

본 연구에서는 PFO와 Coal-tar의 구조와 열 중합 거동 분석을 통해 PFO와 Coal-tar으로 구성된 혼합 원료의 피치 합성 간 제조 특성을 확인하였다. 원소분석과 FT-IR 분석을 통해, PFO와 Coal-tar 각각 0.355, 0.818로 방향족화도 수치를 확인하였다. 또한, PFO와 Coal-tar의 열중량 분석을 통해 질량 감소곡선의 차이를 확인하였으며, 이러한 현상은 방향족 화도와 관능기 함량에 따른 구조적 안정성에 기인한 것으로 판단된다. 피치 제조 특성은 PFO를 원료로 사용한 피치가 혼합원료로부터 제조된 피치보다 평균적으로 낮은 수율과 높은 연화점을 보임을 확인하였다. 특히 유사한 연화점을 가지는 P360 (138.5 ℃)과 B420 (141.4 ℃)을 비교하였을 때, 두 피치의 탄화수율은 각각 29.89, 49.03 wt%로 Coal-tar가 혼합된 경우 약 20 wt% 향상됨을 확인하였다. 이러한 결과는 다량의 알킬기를 포함하여 높은 피치 중합 반응성을 가지는 PFO와 높은 열적 안정성을 가지는 Coal-tar의 혼합에 기인한 것으로 판단된다.

• 에너지공학
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• 제26권4호
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• pp.118-126
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• 2017

본 연구에서는 석탄화력보일러에서 고수분탄 및 건조석탄 사용이 연소와 배기배출 특성에 미치는 영향에 대한 전산해석 연구를 수행하였다. 대상 보일러 설계 조건의 성능데이터를 기준으로 보일러 해석 모델 결과를 검증하였으며, 역청탄과 고수분탄 및 건조석탄을 혼소하는 조건에 대한 계산을 수행하였다. 고수분탄 혼소 비율이 높아질수록 가스 수직속도는 증가하였으며, 이는 연료의 노내 체류시간을 줄여 보일러 연소성에 영향을 미칠 것으로 판단된다. 건조석탄을 혼소할 경우 역청탄과 유사한 연소 및 배기배출 특성을 보였다. 고수분탄 혼소 비율이 높아질수록 수분영향에 의해 버너영역에서 연소반응 및 NOx 생성은 감소하였으며, OFA(Over-fire air) 이후에 가스온도와 NOx 생성이 높아지는 결과를 확인하였다.