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500MWe 접선연소식 석탄 보일러의 NOx 저감을 위한 SOFA 최적화 연구
조현빈(Hyunbin Jo),강기섭(Kiseop Kang),박종근(JongKuen Park),류창국(Changkook Ryu),안현수(Hyunsoo Ahn),고영건(Younggun Go) 한국연소학회 2019 KOSCOSYMPOSIUM논문집 Vol.2019 No.5
This study investigated the optimization of separated overfire air (SOFA) on combustion and NOx emission in a retrofitted tangential-firing boiler at a 500 MWe capacity. Computational fluid dynamic (CFD) simulations incorporating advanced coal combustion models were performed for two operating parameters of the boiler. First, the flow rate of SOFA was varied between 15% and 35% of the total air while the flow rate of CCOFA (Close-coupled overfire air) was fixed at 5%. Second, the proportion of SOFA was varied from 0% to 25% while holding the flow rate of total OFA was fixed at 25%. When compared with the operation data, the CFD results showed reasonable agreement in terms of the heat distribution of the boiler and NOx emission for the reference case. The NOx emission at the furnace exit was reduced by up to 33% but unburned carbon in fly ash was increased by 3 times when the flow rate of SOFA increased to 35%. When the total OFA was fixed at 25%, increasing the SOFA reduced both the NOx emission and unburned carbon up to a ceratin proportion, and then increased them. This suggests that the combustion air distribution can be optimized between SOFA and CCOFA for reduction of both NOx and unburned carbon.
콘크리트의 소수성 표면처리를 통한 철강 보강재의 내식성 향상
조현빈(Hyunbin Jo),신동민(Dongmin Shin),서은혜(Eunhye Seo),이욱진(Wookjin Lee),이정훈(Junghoon Lee) 한국표면공학회 2020 한국표면공학회지 Vol.53 No.6
Corrosion of reinforcement steel rebar is a serious problem in a wide range of concrete application for buildings and infrastructures. Hydrophobizing surface treatments, such as self-assembled monolayer coating, edible oil-impregnation and silicone oil-impregnation were applied to solidified concrete. The hydrophobizing of concrete significantly reduces an absorption and transportation of water toward a steel rebar in concrete, so that the corrosion resistance of the steel rebar. In particular, the silicone oil-impregnation not only forms the hydrophobic monolayer on the concrete but also fills the inter-connected pores of concrete, thus the corrosion of steel rebar is significantly inhibited compared to the self-assembled monolayer coating and edible oil-impregnation. Therefore, the silicone oil-impregnation can be a promising candidate for preventing corrosion of steel rebar in concrete for durable performance and safety.
화력발전 보일러 출구 NOx 농도 선행 예측을 위한 딥 러 닝 모델
조현빈(Hyunbin Jo),강동협(Donghyup Kang),박성민(Seongmin Park),이종욱(Jongwuk Lee),류창국(Changkook Ryu) 한국환경에너지공학회 2022 한국열환경공학회 학술대회지 Vol.2022 No.2
석탄화력에 서의 NOx 발생 최소화는 미세먼지 저감을 위한 주요 이슈 중 하나인데, 최근 신재생 에너지 공급 중가론 석탄 화력의 잦은 출력 변동으로 인해 질소산화물 저감 설비인 SCR(Selective Catalytic Reaction) 의 운전이 더욱 고도화될 필요가 있다. SCR의 암모니아 투입량은 보일러 연소 배가스의 유량과 NOx 농도에 의해 결정되는데, 효율적인 유량 제어를 위해 빠르고 정확하게 보일러 연소 배가스의 NOx 농도를 취득하는 것이 중요하다. 본 연구에서는 석탄화력의 운전 데이터를 이용하여 보일러 출구의 NOx 농도를 실시간으로 선행 예 측하는 딥러닝 모델 및 방법론을 개발했다. 연구 대상 설비는 한국형 표준화력으로 500MWe 급 접선연소식 보일러 이며, 모델 학습 및 평가에 사용된 운전 정보는 약 5개월 동안 81개 항목의 1분 간격의 데이터이다. 수집된 데이터는 전처리를 통해 석탄 공급량, 공기량, 버 너 각도 등을 포함한 19개의 입력 변수로 압축하였고, 데이터 특성에 맞는 딥러닝 모델을 조합하여 1분 후의 보일러 출구에서의 NOx를 포함한 산소 농도와 배가스 온도를 예 측하는 모델을 구성하였다. 모델 예측 성능을 분석한 결과, 본 연구에서 개발한 학습 기법을 이용하여 보일러 출구값을 예측하는 경우 기촌 모델들과 비교하여 평균적으로 약 40%의 예측 성능 향상을 보였다. 따라서, 이룰 기반으로 SCR 설비 운전의 최적화가 가능하며, 소각로 등 유사한 고체연료 연소로의 탈질설비 성능 최적화에 도 적용할 수 있을 것으로 예상된다
딥러닝 기반 화력발전 보일러 출구 NOx 농도 선행 예측 모델
조현빈(Hyunbin Jo),강동협(Donghyup Kang),박성민(Seongmin Park),이종욱(Jongwuk Lee),류창국(Kang Y. Huh) 한국연소학회 2022 KOSCOSYMPOSIUM논문집 Vol.2022 No.11
In this study, we developed a deep learning model to forecast the NOx and oxygen concentration, and gas temperature at the boiler exit of a coal-fired power plant. The target boiler is a 500 MWe tangential firing boiler, which is one of 20 units often referred to as standard coal power plant. From the database of the power plant, 73 raw items of operation data with one-minute frequency were collected for a period of approximately 5 months. Through the feature selection procedure, the raw data items were condensed into 19 features which include coal feeder throughput to burners, air flow rate, and burner tilt. The features were then used to establish two types of data segments: segment #1 for current operation status and segment #2 for recent histories measured at the boiler exit. Considering the large fluctuations, the histories of the recent values at the boiler exit values were averaged over 5 min. After evaluating different prediction models with respect to the nature of the data segments, suitable models were applied in the form of ensemble model to forecast the boiler exit values 1 min in advance. When compared to measured data, the prediction quality was sufficiently high with a mean square error of 0.0123 for NOx emission.
석탄화력 내 암모니아 혼소율에 따른 연소 및 NOx 발생 특성에 대한 전산해석 연구
강우석(Woosuk Kang),조현빈(Hyunbin Jo),류창국(Changkook Ryu) 한국연소학회 2021 KOSCOSYMPOSIUM논문집 Vol.2021 No.11
This study analyze the combustion and NOx emission characteristic of NH₃ cofiring in a commercial pulverized coal boiler using computational fluid dynamics (CFD). Four different methods of NH3 supply at a cofiring ratio of 10% on a higher heating value(HHV)-based thermal input were evaluated while fixing total stoichiometric ratio at 1.08 and that for the burner zone at 0.84. In addition to advanced coal conversion models, global reaction mechanism for NH₃ combined with fuel and thermal NOx mechanisms was established for preliminary evaluation of NH₃ cofiring. For the reference case, the CFD results showed reasonable agreement with the operation data in terms of heat distribution and NOx emission. When NH3 was cofired, the total heat absorption significantly decreased by lower flame temperatures. However, the boiler efficiency was similar on a lower heating value (LHV) base. Therefore, the thermal input of NH₃ and corresponding boiler effienciy need to be determined using the LHV. NOx emission increased by NH₃ cofiring but significant differences were observed between the cofiring method. In particular, concentrating NH₃ supply in a particular burner level exhibited lower NOx emission, indicating that NH₃ cofiring method can be optimized to reduce the NOx emission. The NOx emission required further investigations with an improve NH₃ combustion model.
연어(Oncorhynchus keta)의 밀양강 분포 및 소상 한계선 파악
홍동현,성기백,고의정,정은송,조현빈,주기재,Hong, Donghyun,Seong, Ki Baik,Ko, Eui-Jeong,Jung, Eunsong,Jo, Hyunbin,Joo, Gea-Jae 한국하천호수학회 2020 생태와 환경 Vol.53 No.4
본 연구는 낙동강지류인 밀양강에 소상한 연어를 대상으로 소상, 산란 분포를 최초로 파악하고 소상 한계선을 확인하였다. 2020년 10월 25일부터 11월 28일까지 확인된 개체들 중, 사체는 전장을 측정하고 암-수 구별을 하였다. 조사 결과 총 40개체의 연어를 발견하였으며 이 중 사체는 25마리, 살아있는 개체는 15마리였다. 대부분 산란장으로 판단되는 지점 인근 수변부에서 살아있는 개체와 사체가 발견되었다. 연어의 소상 한계선 파악의 경우 연어가 소상할 수 없는 형태의 보가 등장할 때까지 상류방향으로 이동하여 확인하였으며, 밀양강 본류의 경우 예림교 기준 상류 13 km, 지천인 단장천의 경우 밀양강 합류부에서부터 12 km까지 연어의 소상이 가능할 것으로 확인하였다. 따라서 연어가 소상하기 위한 보의 철거 및 어도설치와 같은 하천연결성 확보가 필요한 것으로 판단되며, 연어의 치어생존률을 높이기 위한 산란장 및 미소서식처 자연성 확보 방안이 필요할 것으로 판단된다. In this study, we carried out a distribution and migration boundary lines of chum salmon (Oncorhynchus keta) in the Milyang River. We measured the total length of dead chum salmons. As a results, 40 chum salmons were found during the study period, 25 dead salmons and 15 alive individuals. The ratio of female was 64%. We verified the migration boundary lines of chum salmons based on a sighting survey until detecting a structure that chum salmons are not able to migrate upstream. We discovered that chum salmons were not able to migrate up to 13 km in a mainstream of the Milyang River and up to 12 km in the Danjang stream (a tributary of the Milayang River) from upstream of the Yerim Bridge. Therefore, our results indicate that Milyang River should improve a river connectivity by demolishing weirs that disturb chum salmon's migration or installing appropriate fishways. Also, effective legislations are needed to retain naturality in spawning ground and micro-habitats to increase the survival rate of parrs and smolts.
고정층 연소 시 공기 유량 및 산소 농도에 따른 SRF의 화염 전파 및 연소 특성에 대한 실험적 연구
김희윤(Heeyoon Kim),조현빈(Hyunbin Jo),박성민(Seongmin Park),김민수(Minsu Kim),류창국(Changkook Ryu) 한국연소학회 2023 KOSCOSYMPOSIUM논문집 Vol.2023 No.11
Incineration is the main thermal treatment for various solid wastes. Although the combustion technology on a moving grate is well-established, the furnaces often have an issue of high-temperature pockets by rapid volatiles release and damages to refractory caused by an increase in the heating value of wastes exceeding the design limit. THe introduction of flue gas recirculation (FGR) to primary air can be a solution to alleviate the high-temperature pockets in the early stage of combustion. This study investigates the combustion characteristics of solid refuse fuel (SRF) in a lab-scale fixed bed, focusing on variations in air flow rate (300-800 ㎏/m²h) and oxygen concentration burning rates at a low air flow rate by the flame front quickly propagating through the surface of particles. Nonetheless, the ignition and burning rates decreased exponentially introduced to the primary air can be an effective measure to control the propagation of ignition front and release of volatiles to the furnace