• 청정기술
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• 제21권2호
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• pp.117-123
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• 2015

본 연구는 LNT (lean NOx trap)용 DeNOx 촉매를 개발하기 위해 시도하였다. 이를 위해서 예비실험을 통해 Pt등 귀금속류등의 PGM (platinum group metal)을 사용하지 않는 4개의 촉매, Al/Co/Mn, Al/Co/Ni/Mn, Al/Co/Mn/Ca, Al/Co/Ni 혼합 금속 산화물을 선정하였다. 또한, 이들의 물리화학적인 성질을 평가하기 위해 XRD, EDS, SEM, BET 및 TPD test를 실시하였다. 이러한 평가를 실시한 결과, 4종의 촉매들은 스피넬(spinel)구조를 가지는 결정으로 이루어졌으며 NOx 기체들의 산화-환원 반응이 이루어지기에는 충분한 기공부피와 기공크기를 갖고 있음을 알 수 있었다. 또한, TPD test를 통해서는 산화-환원이 일어날 수 있는 산점을 4종의 촉매가 모두 가지고 있음을 확인하였다. 더욱이 ramp test를 통해서는 상용(commercial) 촉매와 비슷한 NO 산화 능력을 가지고 있는 것도 확인할 수 있었다. 이상의 결과들을 바탕으로, 본 연구에서 선정된 촉매들을 기본으로 하여 조성성분의 변화 및 활성 성분 첨가 등을 한다면, 보다 개선된 LNT용 DeNOx 촉매를 얻을 수 있을 것이라 기대할 수 있었다.

• 청정기술
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• 제14권2호
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• pp.117-122
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• 2008

중발열량 석탄 합성가스의 연소 및 NOx 발생 특성에 대한 이론적 해석을 수행하였다. 석탄 합성가스는 CO, $H_2,\;CO_2,\;N_2$가 주성분이고, 미량의 $CH_4$ 및 $NH_3$를 함유하는 것으로 가정하였다. 열화학적 해석을 통해 합성가스 연소 시의 화염 온도, 배기가스의 주요 및 부차적 화학종들의 조성, 열 및 연료 NOx 발생량을 계산하였다. 또한 합성가스 중의 $CH_4$ 및 $NH_3$ 성분이 연소 및 NOx 발생에 미치는 영향을 검토하였다. 본 석탄 합성가스들의 계산결과들을 토대로 가스터빈 연소기의 NOx 저감 설계에 필요한 기본 방향과 기준을 제시하였다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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• pp.227-234
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• 2004

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion(CLC) may yield great advantages of savings of energy to $CO_2$ separation and suppressing the effect on environment. In chemical-looping combustor, fuel is oxidized by metal oxide medium (oxygen carrier particle) in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. The purpose of this study is to demonstrate inherent $CO_2$ separation and no NOx emission and to confirm high $CO_2$ selectivity, no side reaction (i.e., carbon deposition, hydrogen generation) by continuous reduction and oxidation experiment in a 50kWtb chemical-looping combustor. NiO/bentonite particle was used as a bed material and $CH_4$ and air were used as reacting gases for reduction and oxidation respectively.

• 한국자동차공학회논문집
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• 제9권4호
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• pp.77-84
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• 2001

Measurements of local CO, $CO_2$, $O_2$, $N_2$, $C_3$H$_{8}$, NOx concentrations and flame temperature are made for partially premixed flame with and without acoustic excitation. The CO, $CO_2$, $O_2$, $N_2$, and $C$_3$H_8$ concentrations are determined by thermal conductivity detection (Gas-chromatograph) and NOx concentrations are determined by chemiluminescent detection (NOx analyser). To measure local sample concentration, sampling probe was made by quartz with inlet diameter of 0.25mm. In the case of excitation, the visual shape of the flame is changed from laminar flame to turbulent-like flame. The flame length is also reduced, and the flame width becomes broad. In the observation of emission concentration without acoustic excitation, meanwhile, the $CO_2$ and NOx concentrations peak at flame front where the mixture meets with surrounding air, and the CO concentration is increasing at maximum position of CO2 concentration and peaks at the centerline of the burner. In the case of acoustic excitation, the $CO_2$ concentration is widely occurred at nozzle of the burner and is higher relative to unexcitation. The CO concentration is much reduced, but NOx concentration is more increasing. And flame temperature is higher relative to unexcitation. These are caused by enhancing of mixing with surrounding air due to excitation. However, in the case of acoustic excitation, the total NOx concentration is reduced because of the shortened flame length which affects residence time.e.

• 한국건설순환자원학회논문집
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• 제11권3호
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• pp.267-275
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• 2023

시멘트 산업은 다양한 가연성 폐기물을 천연자원인 유연탄을 대체하는 연료로 사용함으로써 폐기물 처리 문제 해결에 기여하고 있다. 시멘트 제조공정에서 더 많은 폐합성수지 등 대체연료를 사용하기 위해서는 대체연료를 안정적으로 연소시키고, 특히 NOx와 같은 유해물질의 대기배출을 저감할 필요가 있다. 본 연구는 폐합성수지 등 대체연료의 사용량을 증대시키면서 NOx와 같은 대기배출 유해물질의 발생량을 저감하는 기술의 하나인 다단연소 공정에 대한 사례연구다. 실제 시멘트 제조설비에의 기술 적용 전후 연료 사용량, NOx 배출 등을 비교하여 효과를 평가한 결과, 유연탄의 사용량은 38 % 감소, 폐합성수지 사용량은 122 % 증가하면서 동시에 NOx 배출량은 17 % 저감된 것으로 평가되어 다단연소에 의한 폐합성수지 사용 증대 및 NOx 배출 저감 효과가 유효함을 확인하였다.

• 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.

• 한국항공우주학회지
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• 제41권8호
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• pp.639-648
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• 2013

본 논문은 부게넘 및 태안 IGCC플랜트의 연료를 대상으로 석탄으로부터 생성된 합성가스의 NOx/CO배출 특성, 온도특성, 화염의 구조에 대해 기술하였다. GE7EA 모사 가스터빈 연소기를 대상으로 상압 고온 연소시험을 수행하여 입열량 및 질소희석에 따른 연소특성을 관찰하였다. 입열량이 감소하고, 희석제량이 증가할 때 단열화염온도의 감소로 NOx가 감소하였고, 저부하에서는 희석량이 증가할수록 불완전 연소로 인해 CO가 증가하였다. 이러한 NOx 감소 및 CO발생은 각각 $1500^{\circ}C$ 와 $1250^{\circ}C$의 특정 화염온도에서 관찰되었다. 또한 질소 희석이 증가할수록 단열화염온도 및 연소기 라이너의 온도가 감소했고, 화염 부상과 같은 화염구조의 변화로 인해 특이점이 관찰되었다. 본 연구결과를 통해 질소희석이 NOx/CO배출 및 온도, 화염구조에 미치는 영향이 검토되었으며, 시험 데이터는 향후 태안 IGCC 플랜트의 운전시 최적 조건 선정을 위한 기초자료로 활용될 예정이다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.59-60
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• 2012

This paper describes gas turbine combustion characteristics of synthetic gas which is mainly composed of hydrogen and carbon monoxide. The combustion characteristics such as combustion instability, NOx and CO emission, temperatures at turbine inlet, liner and dump plane, and flame structure were investigated when changing when changing $H_2:CO$ ratio, dilution ratio, and $CH_4:syngas$ ratio. From the results, quantitative relationships are derived between key aspects of combustion performance, notably NOx emission. It is concluded that NOx emission of syngas is strongly influenced by the diluent heat capacity and combustion instability. Moreover, NOx control method using diluents such as $N_2$, $CO_2$, steam is verified.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2008년도 추계학술대회 논문집
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• pp.153-156
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• 2008

MILD combustion has been successfully applied to gaseous fuels and few commercial systems are now in operation. Extending MILD combustion applicability to solid fuel of sawdust is the focus of the present work. The MILD combustion furnace at the University of Adelaide in Australia was used in this study. A measurement of $O_2$ and CO emissions have been carried out in parallel with consideration of NOx emission and compared in each modes of conventional natural gas combustion, natural gas MILD combustion, NOx emission in natural gas MILD combustion mode can be reduced to 20% in comparison with conventional combustion. Emission in cases of air carrying sawdust combustion and $CO_2$ carrying sawdust combustion were also compared. Air and $CO_2$ were sued as a carry gas for the sawdust. It was found that MILD conditions are possible for sawdust particles of less than $355{\mu}m$ without additional air pre-heating. It was also found that when using $CO_2$ as the carry gas the flame inside the furnace was not visible anymore and that NOx emission dropped to less than two folds.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.949-955
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• 2000

Numerical study with detailed chemistry has been conducted to investigate the NOx formation and structure in $CH_4/Air-CO_2$ counterflow diffusion flames. The importance of radiation effect is identified and the role of $CO_2$ addition is addressed to thermal and chemical reaction effects, which can be precisely specified through the introduction of an imaginary species. Also NO separation technique is utilized to distinguish the contribution of thermal and prompt NO formation mechanisms. The results are as follows : The radiation effect is dominant at low strain rates and it is intensified by $CO_2$ addition. Thermal effect mainly contributes to the changes in flame structure and the amount of NO formation but the chemical reaction effect also cannot be neglected. It is noted that flame structure is changed considerably due to the addition of $CO_2$ in such a manner that the path of methane oxidation prefers to take $CH_4 {\rightarrow}CH_3{\rightarrow}C_2H_6{\rightarrow}C_2H_5$ instead of $CH_4 {\rightarrow}CH_3{\rightarrow}CH_2{\rightarrow}CH$. At low strain rate(a=10) the reduction of thermal NO is dominant with respect to reduction rate, but that of prompt NO is dominant with respect to total amount.