• Journal of Information Processing Systems
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• 제15권1호
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• pp.189-202
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• 2019

During thermal power coal-fired boiler operation, it is very important to detect the pulverized coal concentration in the air pipeline for the boiler combustion stability and economic security. Because the current measurement methods used by power plants are often involved with large measurement errors and unable to monitor the pulverized coal concentration in real-time, a new method is needed. In this paper, a new method based on microwave circular waveguide is presented. High Frequency Electromagnetic Simulation (HFSS) software was used to construct a simulation model for measuring pulverized coal concentration in power plant pipeline. Theoretical analysis and simulation experiments were done to find the effective microwave emission frequency, installation angle, the type of antenna probe, antenna installation distance and other important parameters. Finally, field experiment in Jilin Thermal Power Plant proved that with selected parameters, the measuring device accurately reflected the changes in the concentration of pulverized coal.

• 한국연소학회지
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• 제11권4호
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• pp.22-26
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• 2006

To meet the environmental requirements, Doosan Heavy Industries & Construction Co., Ltd. (Doosan) had developed low NOx pulverized coal burner and it was applied to boiler retrofit project, 130 ton/hr coal fired cogeneration boiler, in 2003. NOx emissionand unburned carbon (UBC) in fly ash were measured during the commissioning tests. In this paper, the operation results of low NOx pulverized coal burner installed in 130 ton/hr coal fired boiler are presented. Burners emitted 160 ppm (@6 % $O_2$ basis) NOx and 3 % UBC with Chinacoal containing 0.86 % fuel nitrogen. And also it was shown that NOx emission rate of low NOx pulverized coal burner is linearly increased with fuel-nitrogen fraction of coal.

• 플랜트 저널
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• 제8권1호
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• pp.73-80
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• 2012

The structure and combustion characteristics, and the economic feasibility of the circulating fluidized bed combustion(CFBC) boiler using low grade coal were introduced. The economic feasibility is evaluated by comparing a 500 MW CFBC boiler power plant using low grade coal and a pulverized combustion boiler power plant with high grade coal. As the result of the evaluation, the pulverized coal combustion boiler power plant has an internal rate of return of 12.95%, 1,395.9 billion Korean won of net present value, and 6.26 years of payback period. On the other hand, CFBC boiler power plant has an internal rate of return of 13.54%, 1,704.3 billion Korean won of net present value, and 6.02 years payback period. Therefore, the CFBC boiler power plant has better feasibility in all aspects, as 0.59% higher of internal rate of return, 308.4 billion Korean won of higher net present value and 0.24 year of shorter payback period.

• 에너지공학
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• 제26권4호
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• pp.118-126
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• 2017

본 연구에서는 석탄화력보일러에서 고수분탄 및 건조석탄 사용이 연소와 배기배출 특성에 미치는 영향에 대한 전산해석 연구를 수행하였다. 대상 보일러 설계 조건의 성능데이터를 기준으로 보일러 해석 모델 결과를 검증하였으며, 역청탄과 고수분탄 및 건조석탄을 혼소하는 조건에 대한 계산을 수행하였다. 고수분탄 혼소 비율이 높아질수록 가스 수직속도는 증가하였으며, 이는 연료의 노내 체류시간을 줄여 보일러 연소성에 영향을 미칠 것으로 판단된다. 건조석탄을 혼소할 경우 역청탄과 유사한 연소 및 배기배출 특성을 보였다. 고수분탄 혼소 비율이 높아질수록 수분영향에 의해 버너영역에서 연소반응 및 NOx 생성은 감소하였으며, OFA(Over-fire air) 이후에 가스온도와 NOx 생성이 높아지는 결과를 확인하였다.

• 대한기계학회논문집B
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• 제33권10호
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• pp.737-747
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• 2009

This study is to investigate the effect of the moisture, volatile matter and particle size in the coal on the pulverized coal combustion characteristics using CFD. The results show that as the moisture content in coal increases, flame temperature decreases because of heat loss driven from latent heat of vaporization and reduction of heating value. As the volatile matter content in the coal increases, the temperature in the region near the burner increases, while the temperature in rear region of boiler decreases. The solution to keep the temperature in the rear region of boiler is suggested that particle size is needed to be larger. As the particle size increases, the temperature in the rear region of boiler show tendency to increase, for combustion burning time of coal could be extended.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.87-90
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• 2013

In pulverized coal fired boilers, slagging and fouling may cause significant effect on the operational life of boiler. As increasing a consumption of low rank coal, slagging and fouling are main issues in pulverized coal combustion. This study predicts ash deposition propensity in a 0.7 MW pilot-scale furnace. Slagging model is employed as a User-Defined Function (UDF) of FLUENT and validated against measurement and prediction. The results show good agreement compared with experiment. There is need to development of a pulverized coal combustion and slagging analysis at low coal.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.59-62
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• 2014

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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1751-1755
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• 2004

Increasing environmental pressures to reduce NOx emission are being placed on coal-fired boilers. To meet the environmental requirements, Doosan Heavy Industries & Construction Co., Ltd.(Doosan) has developed low NOx pulverized coal burner. Low NOx pulverized coal burner has already delivered, and it's combustion performance was evaluated to the NOx and Unburned Carbon(UBC) during the commissioning tests. The test results are shown that the strong relationship is existed between NOx and OFA flow rate, and also fuel-N fraction of coal has effected on NOx emission.

• 한국연소학회지
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• 제20권3호
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• pp.35-42
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• 2015

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.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2013년도 제46회 KOSCO SYMPOSIUM 초록집
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• pp.91-94
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• 2013

Commercial computational fluid dynamics (CFD) codes traditionally rely on the computational efficiency of the simplified single-film apparent char kinetic model to predict char particle temperatures and char conversion rates in pulverized coal boilers. The aim of this study is to evaluate the reliability of the single-film apparent kinetic model and to suggest the importance of proper use of this model. For this, a parametric study was conducted with a consideration of main parameters such as Stefan flow, product species, particle evolution, and kinetic parameters.