http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
접선연소식 석탄화력 보일러에서 최적 암모니아 혼소 방안에 대한 전산해석 연구
구윤하(Yunha Koo),박종민(Jongmin Park),강우석(Woosuk Kang),조현빈(Hyunbin Jo),박상빈(Sangbin Park),백세현(Sehyeon Beak),이종민(Jongmin Lee),류창국(Changkook Ryu) 한국연소학회 2022 KOSCOSYMPOSIUM논문집 Vol.2022 No.11
NH₃ co-firing has recently emerged as an urgent issue for CO₂ emission reduction by displacing the fossil fuel in coal-fired power plants. The ideal method for NH₃ cofiring requires to minimize the NOx emission while achieving similar boiler performance in terms of flame stability, combustion efficiency, and heat distribution. This paper presents the results of preliminary study for NH₃ co-firing with coal in a tangential-firing boiler using computational fluid dynamics. The location of NH₃ injection was varied between different parts across the burner zone while increasing the ratio of air supply to the separated over-fire air (SOFA). It was found that the NOx emission at the boiler exit greatly depends on the location of NH₃ injection, in which the lowermost burner was found ideal to keep the NOx emission at a similar level to that for coal combustion only. However, the distribution of secondary air requires further optimization because the heat absorption on the furnace wall (evaporator) reduced significantly.
전산해석을 통한 접선연소식 석탄화력 보일러의 암모니아 혼소 최적화 방안 연구
구윤하(Yunha Koo),강우석(Woosuk Kang),하선교(Seonkyo Ha),조현빈(Hyunbin Jo),박상빈(Sangbin Park),백세현(Sehyeon Baek),류창국(Changkook Ryu) 한국연소학회 2023 KOSCOSYMPOSIUM논문집 Vol.2023 No.5
In coal-fired power plants, NH₃ cofiring has emerged as a new strategy to reduce CO₂ emissions. For NH₃ cofiring, it is important to minimize NOx emissions while maintaining boiler performance in terms of flame stability, combustion efficiency, and heat distribution. In this study, various NH₃ co-firing methods of four different NH₃ inlet were evaluated using computational fluid dynamics in a commercial 500 MWe tangential-firing boiler. To suppress fuel NO formation, the burner zone stoichiometric ratio was kept low by increasing the air supply to the separated over-fire air, while the overall excess air ratio was fixed at 15%. Injecting NH₃ through the oil ports at the burner zone with burner zone stoichiometric ratio of 0.75-0.80 result in low NO emissions (194.8~204.8 ppm) while achieving similar combustion efficiency and heat distribution to the reference case of coal combustion only. Additionally, further optimization can be achieved in other cases with different injection locations through changes in secondary air distribution and NH₃ injection speed.
500 MWe급 접선연소식 석탄화력 보일러의 암모니아 혼소 최적화를 위한 전산해석 연구
구윤하(Yunha Koo),강우석(Woosuk Kang),하선교(Seonkyo Ha),조현빈(Hyunbin Jo),백세현(Sehyun Baek),박경일(Kyeongil Park),류창국(Changkook Ryu) 한국연소학회 2023 KOSCOSYMPOSIUM논문집 Vol.2023 No.11
In coal fired power generation, cofiring ammonia replacing coal has emerged as a potential solution to mitigate carbon dioxide. For ammonia cofiring, it is important to minimize NOx emissions while maintaining boiler performance in terms of flame stability, combustion efficiency, and heat distribution. In this study, ammonia cofiring methods varying its inlet, speed, and direction were evaluated using CFD in 500 MWe tangential-firing pulverized coal boiler. To suppress fuel NO formation, secondary air supply around the ammonia inlet was moved to SOFA, resulting in burner zone stoichiometric ratio of 0.8, while the overall excess air ratio was fixed at 15%. When ammonia is injected from the lower part of the boiler where fireball begins to form, endothermic ammonia decomposition delays ignition/combustion of coal, leading to significant decrease in boiler performance. When ammonia is injected from the upper part of the burner zone, ammonia flow moves along the outside of the fireball where is oxygen-rich resulting in increase of ammonia oxidation. By increasing speed of ammonia, it can penetrate fuel-rich fireball leading to decrease in NO emissions. Furthermore, Injecting ammonia with opposite direction promotes the 연료 농후 and reactions of O₂ with unburned gases, while NO emission remains almost the same.
미분탄-암모니아 흔소를 위한 전산해석모델 개발 및 최적 흔소 방안 연구
하선교(Seonkyo Ha),강우석(Woosuk Kang),구윤하(Yunha Koo),박종민(Jongmin Park),조현빈(Hyunbin Jo),류창국(Changkook Ryu),박상빈(Sangbin Park),백세현(Sehyun Baek),이종민(Jongmin Lee) 한국환경에너지공학회 2022 한국열환경공학회 학술대회지 Vol.2022 No.2
미분탄-암모니아 혼소는 최근에 부각된 석탄화력의 탄소 저감 기술로 NOx 발생과 보일러 성능에 큰 영향이 없는 혼소 방식의 개발이 필요하다. 전산유동해석은 다양한 혼소 방안별 성능 예측을 통해 혼소 방식을 최적화하기 위한 핵심 기법으로서 석탄 및 암모니아의 연소, 열전달, NOx 거동 둥에 대한 합리적인 예측이 필요하다. 본 연구에서는 먼저 암모니아 연소 반응의 Global mechanism을 수립하고 기존의 석탄 연소, ThermaJ 및 Puel NOx 반용과의 통합적인 해석 기법을 개발하였다. 그리고, 이를 이용하여 단일스월버너와 접선연소식 보일러 내 암모니아 최적 혼소 방안에 대한 평가를 진행하였다. 암모니아 반용모델은 주요화학종(NH₃, O₂, H₂, N₂, NO, N₂O)으로 구성된 5개 반응을 수립하고, 넓은 온도 및 당량비 조건 범위에서 Okafor detaiJed mechanism의 반응시간과 NO 농도를 기준으로 반용상수롤 최적화하였다. 스월버너는 암모니아를 버너 중앙에서 단순 투입시 혼소율 20% 이상의 조건에서 화염의 안정성 저하와 NOx 배출 중가 동의 문제를 보였다. 따라서, 다양한 암모니아 투입 방식에 대한 추가 연구가 필요하다. 접선연소식 보일러의 경우 암모니아의 투입 위치에 따라 열전달 및 NOx 발생 특성에 큰 차이를 보였다. 특히 최하단 버너에 투입시 NOx 발생은 저하되었으나 보일러 하부 온도 감소에 의해 벽면 열전달이 큰 폭으로 감소하고 보일러 상단 관군부에서의 열전달이 중가하였다. 따라서, 2차공기 배분을 최적화하여 보일러 스팀 측 운전 영향을 최소화하는 방안의 도출이 필요하다.
청정 수소 생산을 위한 용융촉매 기반 천연가스 열분해 기포 반응기의 전산해석
박성민(Seongmin Park),김무경(Mukyeong Kim),구윤하(Yunha Koo),강도형(Dohyung Kang),류창국(Changkook Ryu) 한국연소학회 2022 KOSCOSYMPOSIUM논문집 Vol.2022 No.5
Methane pyrolysis in a bubble column reactor (BCR) of molten catalysts has recently been proposed to produce H₂ without emitting CO₂, while overcoming the limitations of existing technologies for methane-to-hydrogen conversion. In this study, a numerical model for methane pyrolysis in the BCR of molten catalysts was developed. Based on a 1-D simplification of the BCR, continuous liquid and discrete bubble phases were considered. Applying ii to two sets of experiments, the model accurately reproduced the methane conversion at different conditions, and detailed information on the key phenomena was acquired. By comparing the performances of Ni<SUB>(27)</SUB>Bi<SUB>(73)</SUB> and KCl<SUB>(50)</SUB>MnCl<SUB>2(50)</SUB> under the same reaction conditions, a favorable influence of the catalyst density on methane conversion was revealed. The proposed model is an essential tool for developing methane pyrolysis technology to scale-up with high H₂ productivity.
1000 MW<SUB>e</SUB> 대향류 석탄화력 보일러의 최적 암모니아 혼소 방안에 대한 전산해서 연구
하선교(Seonkyo Ha),강우석(Woosuk Kang),구윤하(Yunha Koo),조현빈(Hyunbin Jo),류창국(Changkook Ryu),백세현(Sehyun Baek),김동규(Donggyu Kim),박경일(Kyeongil Park) 한국연소학회 2023 KOSCOSYMPOSIUM논문집 Vol.2023 No.11
This study evaluates various ammonia co-firing methods in a 1000 MWe wall-firing coal boiler using computational fluid dynamics. When ammonia is uniformly injected in all burners at a co-firing ratio of 20%, the flow and temperature characteristics similar to coal-only firing are maintained. While there is a slight increase in NOx emissions, it would be resolved by modifying the burner design. However, extended evaluation for assessing feasibility of this approach is necessary due to the need for replacements for all burners. On the other hand, when ammonia is injected only in a dedicated burner layer without coal, there are notable changes in temperature and heat transfer rate around these burners but the overall heat transfer distribution in the boiler remains similar to coal-only firing, indicating minimal impact on boiler operation. In terms of NOx emission, it is significantly affected by the NH₃ injection location and method; however, modifying burners to ensure rapid ammonia penetration into the center of the boiler is likely to achieve similar NOx emissions levels with the coal-only firing. Moreover, this approach would minimize the need for burner replacement and is advantageous for achieving higher co-firing rate in the future.