• Journal of Energy Engineering
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• v.26 no.4
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• pp.118-126
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• 2017

This study was performed to investigate the characteristics of combustion and emissions in pulverized coal fired boiler for using high moisture coal and dry coal through computational fluid dynamics(CFD). We validated this boiler model with performance data of the boiler. The results of flow characteristics showed that climbing speed of gases was increased as blending ratio of high moisture coal was increased. It can decrease a residence time of fuel in the furnace. And it influence coal combustion. The coal burnout and NOx generation in burner level were decreased as increasing blending ratio of high moisture coal. The gas temperature and NOx formation were increased after OFA level due to coal burnout delay.

• Resources Recycling
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• v.23 no.2
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• pp.81-89
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• 2014

Approximately 8.5 million tons of fly ash and 740,000 tons of briquette ash were produced in 2010. Inefficient recycling of coal ash has been a heavy economic and environmental burden and economical coal ash utilization technologies are required to turn coal ash into valuable resources. In this study the patents and literature were analyzed to understand the present situation of coal ash recycling technologies and to promote utilization of coal ash for producing a non-sintering green cement, geopolymer. The survey was based on the open patents of USA, European Union, Japan and Korea, and the papers in SCI - indexed journals published between 1979 and 2013. Technical key words were used for data collection and noise filtering. Trends of recycling technologies in utilization of coal ash for producing geopolymers were discussed in terms of time periods, countries, companies and various forms of technologies.

• Journal of Energy Engineering
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• v.7 no.1
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• pp.146-156
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• 1998

Fly ash produced in coal combustion is a fine-grained material consisting mostly of spherical, glassy, and porous particles. A physical, morphological, and chemical characteristic of fly ash has been analyzed. This study may contribute to the data base of domestic fly ash, the improvement of combustion efficiency, ash recycling and ash collection in the electrostatic precipitator. The physical property of fly ash is determined using a particle counter for the measurement of ash size distribution and gravimeter. Morphological characteristic of fly ash is performed using a scanning electron micrograph and an optical microscope. The chemical components of fly ash are determined using an inductively coupled plasma emission spectrometry (ICP). The distribution of fly ash size was ranged from 15 to 25 $\mu$m in mass median diameter. Exposure conditions of flue gas temperature and duration within the combustion zone of the boiler played an important role on the morphological properties of the fly ash such as shape, relative opacity, coloration, cenosphere and plerosphere. The spherical fly ash might be generated at the condition of complete combustion. The size of fly ash was found to be increased the with particle-particle interaction of agglomeration and coagulation. Fly ash consisted of $SiO_2\;Al_2O_3\;and\;Fe_2O_3$ with 85% and carbon with 3~10% of total mass.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.49-56
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• 1998

최근 국내의 에너지 수요는 특히 전기에너지 분야에서 급격한 증가추세를 보여왔으며 그 결과 전력생산을 위한 화석연료 중 특히 석탄의 사용량은 해가 갈수록 증가하였으며 이에 따라 다량의 대기오염물질과 온실가스 등이 발생하고 있어서 미래의 석탄 연소시스템들은 높은 열효율과 최소의 대기오염물질 배출을 필요로 하고 있다. (중략)

• Journal of Energy Engineering
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• v.4 no.1
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• pp.5-12
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• 1995

본 연구에서는 자력 및 정전기 선별법에 의한 발전용 석탄의 연소전 탈황탈회 가능성 조사를 미국 PETC와 공동으로 수행하였다. 정전기 선별법에 의한 석탄의 탈황실험은 국내무연탄 및 미국 유연탄 시료를 대상으로 수행하였으며, 본 선별법은 석탄으로부터 유황을 함유하는 광물은 물론 회분을 제거하는데 매우 효율적임을 확인하였다. 또한 본 연구에서는 고강도 자력선별기를 이용하여 국내무연탄에 대한 건식자력선별 가능성을 검토하였다. 삼척 및 동원탄광 시료에 대한 입도별 2단계 선별실험을 수행하였으며, 본 실험 결과 동원탄광 시료가 삼척탄광 시료보다 회분제거가 용이하였으며 유황분의 경우는 두 시료 모두 40∼50% 제거가 가능하였다. 기초실험을 통하여 향후 발전용 석탄의 연소전 탈황탈회처리시스템 개발에 필요한 기초자료를 제시하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.508-516
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• 1989

The objective of this study is to investigate on the pulsating combustion of a granular coal in a Rijke type pulse combustor. The combustor is made of a 120cm long pipe with a honeycomb as a fire grate in the lower half. A fixed amount of coal is laid on the honeycomb and burned downward after ignition by using propane gas. Then the combustion driven acoustic oscillation occurs and makes the combustion pulsate with a very high amplitude. The effect of the pulsation and the air flow rate on the combustion characteristics is examined in comparison with the normal combustion. The non-pulsating combustion is made possible by placing absorbing material under the honeycomb. The combustion phenomena are observed visually, the burning time is measured in order to evaluate the combustion rate, and the variation of the gas temperatures is recorded. It is found that the fuel particle is greatly agitated like boiling by the flow pulsation and the burning-down velocity is so fast that the fuel is burned almost simultaneously. The combustion rate can be increased as twice as that of non-pulsating combustion with increase of the air flow rate. And the combustion becomes clean with less soot deposit and emission.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.2
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• pp.103-108
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• 2014

Using dried sludge as a secondary fuel of a coal-fired power plant is proposed as an alternative option for sludge disposal. Because elemental contents of sludge are different from those of coal, different levels of acidic gas emissions are expected from the co-combustion of sludge with coal. In this study, sludge samples were obtained from 7 sewage treatment plants in Korea. Each sludge sample was combusted together with coal in a lab-scale combustor, and the concentrations of nitrogen oxides ($NO_x$), sulfur dioxide ($SO_2$), hydrogen chloride (HCl), chlorine ($Cl_2$) in the flue gas were analyzed. Compared to the combustion of coal only, $NO_x$ concentration was slightly higher in the flue gas from the co-combustion of coal and sludge. $SO_2$ emission increased with the combustion of sludge due to the higher content of sulfur in sludge than in coal. For most of the tested samples, the concentrations of HCl and $Cl_2$ were varied depending on the chlorine content in the sludge sample.

• Clean Technology
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• v.28 no.2
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• pp.117-122
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• 2022

This study developed and tested an ultra-low NO_x burner in an 80 kW combustion furnace. The experiment was conducted in an 80 kW single burner combustion furnace with changing the swirl numbers, total equivalence ratios, and primary/secondary oxidizer ratios. In this study, liquefied natural gas (LNG) was used as an auxiliary fuel to significantly reduce NO_x production. In a thermal power plant, the amount of NO_x generated during coal combustion is about 300 ppm. However, using the burner tested in this study, it was possible to reduce the amount of NO_x generated via LNG co-firing to 40 ppm. If the input amount of the primary oxidizer is enough for the gas to be completely combusted and the gas and coal are added simultaneously, the combusted gas forms a high-temperature region at the burner outlet and volatilizes the coal. As a result, the N contained in the devolatilized coal is discharged. Therefore, when the coal is subsequently burned, the amount of NO_x produced decreases because there is almost no N remaining in the coal. If a thermal power plant burner is developed based on the results of this study, it is expected that the NO_x generation will be significantly lower in the early stage of combustion.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.41-45
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• 1999

연소 중에 발생하는 주요 공해물질 중의 하나가 질소산화물(NOx)이며 석탄의 연소에서는 타 연료를 사용하는 연소와 비교하여 많은 양의 질소산화물이 생성된다. 이러한 현상은 석탄에 결합되어있는 연료 중 질소(fuel-N)의 산화에 기인한 것이다. 석탄 연소 시 fuel-N에 의하여 생성되는 질소산화물은 전체 질소산화물의 75%이상, 때에 따라서는 95%까지 점하는 결과를 보여 준다.(중략)

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.296-300
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• 2011

In this work, various wood biomasses were used to determine the combustion characteristics for the fuel of cogeneration plant. Combustion characteristics of four types, i.e., (i) forest products, (ii) recycled wood, (iii) empty fruit bunch, and (iv) palm kernel shell, were examined via thermal gravimetric analyzer (TGA) in air atmosphere and coal was used as a comparison group. From the TGA results, the combustion of the wood biomass was occurred in the range of 280 to $420^{\circ}C$, which was lower than that of coal. Forest product showed the lowest activation energy (0.4 kJ/mol) compared to that of other wood biomasses (about 6 to 14 kJ/mol) and coal (64 kJ/mol). In addition, the reaction rate constant of the wood biomass was lower than that of coal. These results indicate the higher combustion initiation rate of wood biomass due to the high content of volatile matter, which had a low boiling point.