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석탄가스화기 내 버너 이상거동에 따른 유동 및 반응특성에 대한 전산해석 연구
남준영(Joonyeong Nam),김무경(Mukyeong Kim),손근(Geun Sohn),류창국(Changkook Ryu),김봉근(Bonggeun Kim) 한국연소학회 2019 KOSCOSYMPOSIUM논문집 Vol.2019 No.11
In a Shell coal gasifier, four horizontally biased coal burners located in the middle of a cylindrical reactor creats a swirling flow at the center that governs the flow and particle behaviors. If the coal burners do not have the identical fuel and oxidant throughput by operational issues or during startup and shutdown, this breaks the axisymmetry of the swirling flow. In this study, the influence of abnormal burner operation was investigated using computational fluid dynamics (CFD) for the coal gasifier empolyed at Taean 300 MWe plant. It was found that the changes in the fuel or oxidant throughput in one burner by 30% can significantly shift the how swirling flow to the wall, creating a region of excessive heat flux to the wall (hot spot). Maintaining the axisymmetry by adjusting one burner pair to the same condition can alleviate this issue. If burners are inevitably to be turned off, the three-burner opeation was better than two-burner operation in terms of the peak heat flux in the hot spots.
태안 IGCC 가스화기의 주요 운전인자별 가스화 성능 영향에 대한 수치해석 연구
남준영(Joonyeong Nam),박성민(Seongmin Park),류창국(Changkook Ryu),이상원(Sangwon Lee),박정하(Jungha Park) 한국연소학회 2022 KOSCOSYMPOSIUM논문집 Vol.2022 No.11
The coal gasifier in an integrated gasification combined cycle (IGCC) have a narrow range of operation window to meet the requirement on syngas composition and properties. In this study, the influences of three main variables (heating value of input solid, oxidant/solid ratio, and flux/solid ratio) on the gasifier performance were evaluated using a reduced order model (ROM) optimized for Taean IGC. The ROM is capable of predicting the dynamics of gas temperature and composition, heat transfer, and the slag thickness on the wall along the height. For actual operating conditions selected for three input solids, the ROM provided good agreement in the gas composition and heat duty. The oxidiant/solid and flux/solid ratios had considerable impact on the heat duty and exit gas temperature. Because the flux/solid ratio is adjusted depending on the ash composition and corresponding viscosity, oxidant/solid ratio is the main operating variable in controlling exit gas temperature and heat duty. It was also found that the heat duty and exit gas temperature were highly sensitive to the heating value, implying that accurate characterization of coal with representative samples is crucial to determine the target operating conditions.
IGCC 석탄 가스화기의 산화제/미분탄 비율 변화에 따른 가스온도, 전열량, 슬래그 거동의 동적 특성 분석
박성민(Seongmin Park),남준영(Joonyeong Nam),류창국(Changkook Ryu),박지은(Jieun Park),이상원(Sangwon Lee) 한국연소학회 2023 KOSCOSYMPOSIUM논문집 Vol.2023 No.5
In an integrated gasification combined cycle (IGCC) coal gasifier, the oxidant/solid ratio (OS ratio) is a critical operational variable that must be carefully controlled based on coal properties and load, However, controlling the OS ratio is challenging due to (i) frequent fluctuations in coal and oxygen flow rates, and (ii) limited information on gasifier status, wife heat duty as the only reliable parameter directly measured from the gasifier under extremely high temperatures and pressures. In this study, the dynamic response of the gasifier to changes in the OS ratio was investigated using a reduced-order model (ROM) optimized for the Taean IGCC in Korea, Different scenarios of OS ratio changes were simulated, including step changes, instant peaks, and oscillations, and the dynamic response of the gasifier was analyzed for three key performance parameters: exit gas temperature, heat duty, and slag thickness. It was found that the exit gas temperature responds immediately to changes in the OS ratio due to short gas residence time but may exhibit an overshoot because of the slower response of the slag layer on the wall. The heat duty had a characteristic response time (τ) of approximately 4 minutes to step changes in the OS ratio, reflecting the gradual change in the slag layer. The slag thickness at the slag tap had the slowest response, with τ on the order of 10 minutes, due to the slow downward flow of the slag. Because of these behaviors, the heat duty and slag thickness followed the average trend of the OS ratio rather than frequent oscillations. These results were able to explain the actual behaviors of heat duty observed in the gasifier and were helpful in improving operation control.