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미분탄 보일러 연소 해석에서 석탄 반응 모델 및 난류 혼합 속도의 영향 평가
양주향,김정은,류창국 한국연소학회 2015 한국연소학회지 Vol.20 No.3
Investigating coal combustion in a large-scale boiler using computational fluid dynamics (CFD) requires a combination of flow and reaction models. These models include a number of rate constants which are often difficult to determine or validate for particular coals or furnaces. Nonetheless, CFD plays an important role in developing new combustion technologies and improving the operation. In this study, the model selection and rate constants for coal devolatilization, char conversion, and turbulent reaction were evaluated for a commercial wall-firing boiler. The influence of devolatilization and char reaction models was found not significant on the overall temperature distribution and heat transfer rate. However, the difference in the flame shapes near the burners were noticeable. Compared to the coal conversion models, the rate constant used for the eddy dissipation rate of gaseous reactions had a larger influence on the temperature and heat transfer rate. Based on the operation data, a value for the rate constant was recommended.
500 MWe급 접선 연소 보일러 해석시 난류 혼합 속도 및 석탄 연소 모델의 영향 평가
양주향(Joo-Hyang Yang),강기섭(Kie-Seop Kang),류창국(Changkook Ryu) 한국연소학회 2015 KOSCOSYMPOSIUM논문집 Vol.2015 No.12
Computational fluid dynamics (CFD) modeling of large-scale coal-fired boilers requires a complicated set of flow, heat transfer and combustion process models based on different degrees of simplification. This study investigates the influence of coal devolatilization, char conversion and turbulent gas reaction models in CFD for a tangential-firing boiler at 500MWe capacity. Devolatilization model is found out not significant on the overall results, when the kinetic rates and the composition of volatiles were varied. In contrast, the turbulence mixing rate influenced significantly on the gas reaction rates, temperature, and heat transfer rate on the wall. The influence of char conversion by the unreacted core shrinking model (UCSM) and the 1st-order global rate model was not significant, but the unburned carbon concentration was predicted in details by the UCSM. Overall, the effects of the selected models were found similar with previous study for a wall-firing boiler.
상용 미분탄 보일러 연소해석에서 석탄 탈휘발 모델 및 난류반응속도의 영향 평가
양주향(JooHyang Yang),김정은(Jung-en A. Kim),류창국(Changkook Ryu) 한국연소학회 2014 KOSCOSYMPOSIUM논문집 Vol.2014 No.11
Predicting coal combustion by computational fluid dynamics (CFD) requires a combination of complicated flow and reaction models for turbulence, radiation, particle flows, heterogeneous combustion, and gaseous reactions. There are various levels of models available for each of the phenomena, but the use of advanced models are significantly restricted in a large-scale boiler due to the computational costs and the balance of accuracy between adopted models. In this study, the influence of coal devolatilization model and turbulent mixing rate was assessed in CFD for a commercial boiler at 500 MWe capacity. For coal devolatilization, two models were compared: i) a simple model assuming single volatile compound based on proximate analysis and ii) advanced model of FLASHCHAIN with multiple volatile species. It was found out that the influence of the model was observed near the flames but the overall gas temperature and heat transfer rate to the boiler were very similar. The devolatilization rate was found not significant since the difference in near-flame temperature became noticeable when it was multiplied by 10 or 0.1. In contrast, the influence of turbulent mixing rate (constant A in the Magnussen model) was found very large. Considering the heat transfer rate and flame temperature, a value of 1.0 was recommended for the rate constant.
IGCC 합성가스 급속 냉각시스템의 운전 압력에 따른 열유동 및 입자 거동 특성 연구
박상빈,양주향,오준호,예인수,류창국,박성구 한국수소및신에너지학회 2014 한국수소 및 신에너지학회논문집 Vol.25 No.1
In a coal gasifier for IGCC, hot syngas leaving the gasifier at about 1550oC is rapidly quenchedby cold syngas recycled from the gas cleaning process. This study investigated the flow and heat transfercharacteristics in the gas quench system of a commercial IGCC process plant under different operating pressures. As the operating pressure increased from 30 bar to 50 bar, the reduced gas velocity shortened the hot syngascore. The hot fly slag particles were retained within the core more effectively, and the heat transfer became moreintensive around the hot gas core under higher pressures. Despite the high particle concentrations, the wall erosionby particle impaction was estimated not significant. However, large particles became more stagnant in the transferduct due to the reduced gas velocity and drag force under higher pressures.
500 MWe급 석탄화력 보일러 내 바이오매스 혼소 특성에 대한 수치적 연구
오준호(Junho Oh),양주향(Juhyang Yang),강기섭(Kieseop Kang),류창국(Changkook Ryu) 한국연소학회 2014 KOSCOSYMPOSIUM논문집 Vol.2014 No.5
This study investigates the co-combustion characteristics of biomass in a coal fired tangential firing boiler in a 500 MWe capacity power plant. The detailed flow, heat and reaction characteristics for different cofiring methods were evaluated using computational fluid dynamics adopting advanced sub-models for combustion of solid fuels. The cofiring of biomass having a lower calorific value led to overall decrease in the gas temperatures of the burner zone and corresponding decrease in NOx emission. The use of dedicated cases for direct cofiring of coal/biomass blends. The results suggest that biomass cofiring method can be optimized for reduced NOx emission.
미분탄 바이오매스 혼소 시 연료 단계 연소를 통한 NOx 저감 특성 연구
강기섭(Kieseop Kang),오준호(Junho Oh),양주향(Joohyang Yang),양원(Won Yang),류창국(Changkook Ryu) 한국연소학회 2015 KOSCOSYMPOSIUM논문집 Vol.2015 No.5
This study investigates the co-combustion characteristics of biomass in a coal fired tangential firing boiler in a 560 MWe capacity power plant. The detailed flow, heat and reaction characteristics for different cofiring methods were evaluated using computational fluid dynamics adopting sub-models for combustion of solid fuels. The cofiring of biomass having a lower calorific value led to overall decrease in the gas temperatures of the burner zone and corresponding decrease in NOx emission. The use of dedicated burners for biomass had different temperature and NOx concentrations, compared to the cases for direct cofiring of coal/biomass blends. The results suggest that biomass cofiring method can be optimized for reduced NOx emission.