• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.25-28
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• 2013

This study presents both experimental and numerical investigation of ignition characteristics of n-heptane and n-butanol mixture. The $O_2$ concentration was fixed to 9-10% to make high exhaust gas recirculation(EGR) rate condition. Experiments were performed using a rapid compression machine. In addition, a numerical study of the ignition delay time was performed using CHEMKIN codes to validate experimental results and predict chemical species after combustion process. The results showed that the ignition delay time increased with increasing n-butanol ratio and the reactivity decreased by low $O_2$ concentration.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.83-85
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• 2013

With an increase in the use of low rank coals in power plants, various operational issues were raised in the fuel storage and supply, combustion, boiler and flue gas treatment systems. In the fuel storage and supply system, the main issue is the self-heating propensity of low rank coals leading to spontaneous combustion in yard storage, transport and pulverization. This study evaluated the reactivity of various sub-bituminous and bituminous coals with oxygen at low temperatures by analyzing the temperature increase characteristics of coals under a constant flow rate of oxygen supply. The results were quantified to a self-heating index and the relation with the fuel properties were evaluated.

• 한국수소및신에너지학회논문집
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• 제33권4호
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• pp.400-412
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• 2022

Hydrogen with high chemical reactivity and combustion efficiency, is expected to reduce greenhouse gas and CO emission. However, there is a problem of increase in NOx emission due to hydrogen combustion. MILD combustion technology has been proposed to resolve NOx emission. In this study, the characteristics of MILD combustion and NOx formation by flue gas recirculation (KV) in CH₄-H₂ mixture were analyzed and predicted using 0D premixed combustion model. The ignition delay time became shorter as the hydrogen co-firing rate increased, and longer as the recirculation rate increased. For NOx emission, EINO decreased as the KV increased, but EINO increased as the hydrogen co- firing rate increased. In particular, EINO was predicted to increase significiently above 80% hydrogen. Through the pathway analysis of NO formation, it was found that the influence of N₂O intermediate route and NNH route was enhanced for hydrogen co-firing.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.843-849
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• 2012

매체순환식 가스연소기 산소공여입자로 NiO 계열 산소공여입자를 사용할 경우 고온 조건(> $900^{\circ}C$)에서 온도가 증가함에 따라 환원반응 배출기체 중 CO 농도가 증가하게 되며, 이에 의해 연료전환율과 $CO_2$ 선택도가 감소하게 된다. 이러한 고온 환원반응성 저하를 개선하기 위한 방법으로 매체순환 가스연소기에 적용 가능한 금속산화물들에 대해 온도변화에 따른 평형 CO 농도를 계산 및 비교하여 반응성 개선이 가능한 금속산화물을 선정하였다. 선정된 금속산화물을 NiO 계열 산소공여입자와 물리적으로 혼합하는 방법을 적용하여 고온 환원반응성 개선이 가능한지를 회분식 유동층 실험장치를 이용하여 측정 및 해석하였다. $900{\sim}1000^{\circ}C$ 범위에서 기존 NiO 계열 입자(OCN706-1100) 만을 사용한 경우에 비해 $Co_3O_4$ 계열 입자($Co_3O_4/CoAl_2O_4$)를 10% 혼합한 경우가 연료전환율 및 $CO_2$ 선택도가 높게 나타났으며 환원반응 배출기체 중 CO의 농도가 감소하는 경향을 나타내어 $Co_3O_4$ 계열 산소공여입자를 함께 사용하는 방법으로 고온 환원반응성 개선이 가능함을 확인할 수 있었다.

• 한국분무공학회지
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• 제21권1호
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• pp.29-36
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• 2016

The effect of high ambient temperature and pressure conditions on the combustion performance of n-butanol, n-heptane and its mixing fuel (BH 20) were studied in this work. To reveal this, the closed homogeneous reactor model applied and 1000-1200 K of the initial temperature, 20-30 atm of initial pressure and 1.0 of equivalence ratio were set to numerical analysis. It was found that the results of combustion temperature was increased and the ignition delay was decreased when the ambient conditions were elevated since the combustion reactivity increased at the high ambient conditions. On the contrary, under the low combustion temperature condition, the combustion pressure was more influenced by the ambient temperature in the same ambient conditions. In addition, the total mass and the mass density of tested fuels were influenced by the ambient pressure and temperature. Also, soot generation of mixing fuel was decreased than n-heptane fuel due to the oxygen content of n-butanol fuel.

• 에너지공학
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• 제14권1호
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• pp.1-10
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• 2005

석탄의 열분해 압력이 촤의 연소 반응성에 미치는 영향을 가압열중량 분석기를 사용하여 고찰하였다. 사용되어진 탄은 알라스카, 아다로, 데니소브스키탄으로서 압력을 상압, 8기압, 15기압으로 변화시키면서 휘발분 방출량을 측정하고 열분해 압렵별로 생성된 촤의 반응성을 상압하 500℃에서 평가하였으며 생성된 촤의 결정구조, 표면적 및 기공특성, 화학적 특성을 분석하였다. 열분해 압력이 증가함에 따라 휘발분 방출량은 감소하였고 고압에서 생성된 촤의 반응성이 작았음을 알 수 있었다. 이는 반응표면적과 기공특성의 차이로 생각되어지며 열분해 압력에 따른 촤의 화학적 특성과 결정구조는 큰 차이를 보이지 않았다. 상압, 5기압 15기압하에서 3개 촤의 연소 반응속도를 측정하였으며 알라스카 촤의 경우, 15기압에서 연소반응성 지수 획득실험을 수행하여 56.8KJ/mole의 활성화에너지, 222.34(1/min)의 빈도계수 값을 얻었다.

• 한국연소학회지
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• 제21권4호
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• pp.23-29
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• 2016

Reactivity of gasification defined by bouardard reaction is critical parameter in efficiency of the gasifier. In this study, char reactivity of the gasification was derived from the experiments using the intrinsic reaction kinetics model. Pressurized wire mesh heating reactor (PWMR) can produce high temperature and high pressure conditions up to 50 atm and 1750 K, respectively and PWMR was designed to evaluate the intrinsic reaction kinetics of $CO_2$ gasification. In this study, Kideco and KCH (sub-bituminous Indonesian coal) were pulverized and converted into char. Experiments used the PWMR were conducted and the conditions of the temperature and pressure were 1373~1673 K, 1~40 atm. To distinguish the pressure effect from high pressurized condition, internal and external effectiveness factors were considered. Finally, the intrinsic kinetics of the Kideco and KCH coal char were derived from $n^{th}$ order reaction rate equations.

• 한국수소및신에너지학회논문집
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• 제27권5호
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• pp.581-588
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• 2016

To compare reduction reactivity of oxygen carrier particles, $CH_4$ combustion characteristics were measured and investigated in a bubbling fluidized bed reactor with increasing $CH_4$ concentration from 10 to 100 %. Among five oxygen carriers (OC-1, OC-2, SDN70, C14, C28), OC-1, OC-2, SDN70 particles were selected as better oxygen carriers from the viewpoints of fuel conversion and $CO_2$ selectivity. However, some oxygen carriers showed lower fuel conversion and $CO_2$ selectivity even though they have high oxygen transfer capacity. Therefore, we could conclude that not only TGA tests to measure the oxygen transfer capacity but also fluidized bed tests to analyze exhaust gas concentration should be performed to select better oxygen carrier without misunderstanding of carriers reactivity.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.47-49
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• 2014

발전소에서 설계 규격을 벗어나는 저등급 석탄을 사용하기 시작하면서, 보일러에서의 연소특성을 예측하기 어려운 다양한 성질의 석탄이 들어오게 되어 각종 연소 문제가 증가하고 있다. 이 중 약 점결 특성을 가지는 저등급 석탄의 사용은 대형 클링커로 인한 보일러 하부의 튜브 손상 사고, 재열증기온도 상승으로 인한 출력감발 등의 문제를 발생시켰다. 또한 현재 개발 중인 무회분석탄 역시 점결 특성을 가지고 있는 것으로 알려져 있어 보일러 내부의 다양한 문제를 일으킬 것으로 예상되고 있다. 발전소에서는 강점결탄 수입 규제를 위해 CSN(Crucible Swelling Number)를 이용하여 제철용으로 사용되는 강점결 석탄의 도입을 규제해왔으나, 발전소 운영에 악 영향을 미치는 약 점결탄에 대한 규제 및 대응으로는 그 효과가 미미한 실정이다. 따라서 본 연구에서는 석탄의 점결 특성 중 팽창 특성을 분석할 수 있는 Microdilatometer와 TGA를 이용한 연소반응성 분석을 통해 석탄의 점결 특성이 연소반응성에 미치는 영향을 분석하였다.

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.95-105
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• 2016

Spray-dried NiO-based oxygen carriers developed for chemical looping combustion required high calcination temperatures above $1300^{\circ}C$ to obtain high mechanical strength applicable to circulating fluidized-bed process. In this study, the effect of CBB ($CaO{\cdot}BaO{\cdot}B_2O_3$) addition, as a binder, on the physical properties and oxygen transfer reactivity of spray-dried NiO-based oxygen carriers was investigated. CBB addition resulted in several positive effects such as reduction of calcination temperature and increase in oxygen transfer capacity and porosity. However, oxygen transfer rate was considerably decreased. This was more apparent when a higher amount of CBB was added and MgO was added together. From the experimental results, it is concluded that CBB added NiO-based oxygen carriers are not suitable for chemical looping combustion and a new method to reduce calcination temperature while maintaining high oxygen transfer rate of NiO-based oxygen carriers should be found out.