• Plant Journal
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• v.18 no.1
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• pp.55-61
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• 2022

In this study, I analyzed the effect of slagging caused by blending bituminous coal and subbituminous coal while maintaining the generator output, combustion conditions, and ventilation conditions for 870MW thermal power plant designed with bituminous coal. Accordingly I proposed an acceptable method of blending coal method. the blending ratio of sub-bituminous coal was adjusted to 10%, 20%, 40%, 60%, 80%, etc. to confirm ultimate analysis, proximate analysis, ash fusion temperature change, slagging indices, etc. Proper blending coal conditions are blending with sub-bituminous coal at 40% or less, ratio of base component to acid component(B/A) is 0.4 or less or 1 or more, total alkali(TA) is 3.5 or less, fusion slagging index(Rfs) is 1,345℃ or more, and ash content is 13% or less in ultimate analysis, the ash content in proximate analysis is 15% or less, and the initial deformation temperature(IDT) should be at least 1,200℃ or more

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.39-41
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• 2012

The influence of coal blending methods such as out-furnace (external or pre-mixed) blending and in-furnace (initially non-mixed) blending with different excess oxygen (highest, medium, and lowest stoichiometric conditions) on unburned carbon and NOx emissions of blend combustion in an entrained flow reactor (EFR) has been analyzed, using experimental and numerical approaches for binary coals used by Korean power plants. The results confirm that under the medium condition, contrasting processes such as reactive and un-reactive effects occur with SBRs in the out-furnace blending method. The in-furnace blending method results in an improvement in the efficiency of unburned carbon fractions and a further reduction in the NOx emission. Under the highest condition, the unburned carbon fraction in both the out-furnace and the in-furnace blending methods corresponds with the tendency under the medium condition with contrasting processes of lower magnitude, whereas the NOx emission in the highest condition increases slightly. Under the lowest conditions, the unburned carbon fraction in the out-furnace blending method gradually decreases as SBR decreases, without a competition effect. The reduction of NOx emission under the lowest conditions is more effective than those under other conditions for the two blending methods because of a homogeneous and heterogeneous NOx reduction mechanism.

• Carbon letters
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• v.25
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• pp.78-83
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• 2018

Pyrolyzed fuel oil (PFO) and coal tar was blended in the feedstock to produce pitch via thermal reaction. The blended feedstock and produced pitch were characterized to investigate the effect of the blending ratio. In the feedstock analysis, coal tar exhibited a distinct distribution in its boiling point related to the number of aromatic rings and showed higher Conradson carbon residue and aromaticity values of 26.6% and 0.67%, respectively, compared with PFO. The pitch yield changed with the blending ratio, while the softening point of the produced pitch was determined by the PFO ratio in the blends. On the other hand, the carbon yield increased with increasing coal tar ratio in the blends. This phenomenon indicated that the formation of aliphatic bridges in PFO may occur during the thermal reaction, resulting in an increased softening point. In addition, it was confirmed that the molecular weight distribution of the produced pitch was associated with the predominant feedstock in the blend.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.3
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• pp.274-284
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• 2012

Recently, gasification technology for coal blended with biomass has been an issue. Especially, An advantages of coal blended with biomass are 1) obtaining high cold gas efficiency, 2) obtaining syn-gas of high-high heating value (HHV), and 3) controlling occurrence of $CO_2$. In this study, the efficiency and characteristic of 300 MW Shell type gasifier were predicted using CFD simulation. The CFD simulation was performed for biomass coal blending ratios of 0~0.2, 0.5, 1 and $O_2$/fuel ratios of 0.5~0.84. Kinetic parameters (A, $E_a$) obtained by $CO_2$ gasification experiment were used as inputs for the simulation. In results of CFD simulation, residence times of particle in 300MW Shell type gasifer presented as 7.39 sec ~ 13.65 sec. Temperature of exit increased with $O_2$/fuel ratio as 1400 K ~ 2800 K, while there is not an effects of biomass coal blending ratios. Considering both aspects of temperature for causing wall slagging and high cold gas efficiency, the optimal $O_2$/fuel ratio and blending ratio were found to be 0.585 and 0.05, respectively.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.42-48
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• 2014

Soot and tar which were derived from combustion or pyrolysis processes in Puverized Coal(PC) furnace or boiler have been significantly dealing in a radiative heat transfer and an additional source of NOx. Furthermore, the increasing for the use of a coal with low caloric value gives rise to a lot of tar-soot yield and LOI in a recycled ash for using cement materials. So, the ash with higher tar-soot yield and LOI can not recycle due to decreased strength of concrete. In this study, tar-soot yields and flame structures were investigated using the LFR for a blending combustion with bituminous coal and sub-bituminous coal. Also, The investigation were conducted as each single coals and blending ratio. The coals are used in a doestic power plant. In the experimental results, sub-bituminous coal with high volatile contents shows longer soot cloud length than bituminous coal, but overall flame length was shorter than bituminous coal. Tar-soot yields of sub-bituminous coal is lower than those of bituminous coal. Combustion characteristics are different between single coal and blended coal. Therefore, finding an optimal coal blending ratio according to coal rank effects on tar-soot yields.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.65-73
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• 2010

In order to provide fundamental information for developing reaction model in the practical blended coal power plants, effects of particle size and blending ratio on combustion characteristics and thermal reaction in co-firing with bituminous and sub-bituminous coals were experimentally investigated using a TGA and a laboratory-scale burner. Characteristic parameters including ignition, burnout temperature and activation energy were determined from TG and DTG combustion profiles. Distributions of flame length and mean particle temperature were investigated from the visualization of flames in slit-burner system. As coal particle size decreased and volatile matter content increased, characteristic temperatures and activation energy decreased. The ignition/burnout characteristics and activation energy are linearly influenced by a variation in particle size and blending ratio. These results indicated that the control of the coal blending ratio can improve the combustion efficiency for sub-bituminous coals and the ignition characteristics for bituminous coals.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.10b
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• pp.113-122
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• 1996

본 연구는 석탄가스화복합발전(IGCC)의 핵심부분이라 할 수 있는 슬래깅 형태의 분류층 가스화기에 원활한 Slagging을 유지하기 위해 Flux addition method와 Coal blending method를 적용하였다. 대상탄으로는 가스화에 적합하다고 알려진 알라스카탄, 대동탄과 비교탄으로 가스화에 부적합하다고 알려진 1종류의 유연탄을 대상으로 기본분석 및 화학적 조성분석, 용융온도를 측정하여 봄으로써 대상탄들의 슬래깅성향을 평가하였다. 대동탄과 알라스카탄에 대해서는 Flux addition method를 적용하고, 비교탄에 대해서는 Coal blending Method를 적용한 후, 140$0^{\circ}C$로 운전되는 가스화기의 효율을 최대화할 수 있는 Flux 첨가비와 blending ratio를 산정하였다.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.784-787
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• 2007

A process flowsheet simulation model based on ASPEN PLUS was developed to investigate the effect of co-gasification of coal and rice husk on the gasifier performance and pollutant emissions in IGCC power plant. The analyses were done for an 02-blown, pulverized gasifier using coal and rice husk as feedstock, parameter employed the blending ratio of rice husk in coal were investigated. From the simulation results, it was found that gaseous pollutant emissions were reduced substantially with the increase of the blending ratio of rice husk. An optimum range between 15% and 25% rice husk-to-coal ratio was found to be the optimum point in terms of gaseous pollutant emission per energy output for sui fur and nitrogen compounds.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.1
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• pp.53-59
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• 2015

Combustion characteristics for co-firing of biomass (Walnut Shell) as blending fuel in coal fired boiler have investigated using thermogravimetric analyser (TGA) and drop tube reactor (DTR). The results show that devolatilization and char combustion for WS occurs at lower temperature than those of existing coals and has lower activation energy value, which is resulting in higher reactivity. When the WS is blended with coal, TGA results show linear profiles depending on blending ratio for each fuel. However, DTR results exist the non-additive phenomena for blending of WS. As blending ratio of WS increase, the UBC decrease at BBR 5%, but the UBC rather increase from BBR 10% due to oxygen deficiency formed from rapid combustion of WS. This paper propose that fuel lean condition by oxygen rich lead to higher blending ratio of biomass by solving the oxygen deficiency condition.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.1
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• pp.31-37
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• 2016

Co-firing of biomass with coal is a promising combustion technology in a coal-fired power plant. However, it still requires verifications to apply co-firing in an actual boiler. In this study, data from the Thermogravimetric analyzer(TGA) and Drop tube furnace(DTF) were used to obtain the combustion characteristics of biomass when co-firing with coal. The combustion characteristics were verified using experimental results including reactivity from the TGA and Unburned carbon(UBC) data from the DTF. The experiment also analyzed with the variation of the biomass blending ratio and biomass particle size. It was determined that increasing the biomass blending ratio resulted in incomplete chemical reactions due to insufficient oxygen levels because of the rapid initial combustion characteristics of the biomass. Thus, the optimum blending condition of the biomass based on the results of this study was found to be 5 while oxygen enrichment reduced the increase of UBC that occurred during combustion of blended biomass and coal.