와류 발생기를 장착한 가스터빈 연소기에서 연료/공기 혼합 및 NOx 배출 특성에 관한 수치적 연구

김구(Gu Kim),이영덕(Young Duk Lee),손채훈(Chae Hoon Sohn) 한국연소학회 2013 한국연소학회지 Vol.18 No.3

가스터빈용 희박 예혼합 연소기 내부에 와류 발생기(vortex generator)를 장착하여 그에 따른 연료/공기혼합 및 NOx 배출 특성 변화를 조사하였다. 이를 위해 수치해석적 방법을 채택하여 연소기내 유동특성, 연료/공기 혼합도, 배기가스(NOx), 화염형상을 분석하였다. 와류 발생기를 장착한 경우, 연소기 내부에서 와류 발생기에 의한 나사산 형상으로 인해 와류가 형성되며 이는 연소기 전면부까지 유지되었다. 또한 연소기 내부 면적 차로 인해 압력섭동이 발생하였다. 이와 더불어 연소기 전면부 기준 상류지역의 연료와 공기의 혼합도가 증가됨으로서 연료 과농지역이 감소하게 되며 이로 인해 전반적인 NOx 발생량의 감소 효과를 볼 수 있었다. 화염 형상의 변화로부터 와류 발생기의 영향으로 선회수는 다소 감소할 것으로 예상되며, 이는 와류 발생기로 인한 유속의 반복적 증감에 의한 결과라고 판단된다.

배가스 재순환 적용을 위한 제철 소결 베드 프로세스 모델링

안형준(Hyungjun Ahn),최상민(Sangmin Choi),조병국(Byungkook Cho) 한국연소학회 2011 한국연소학회지 Vol.16 No.4

In the iron and steel manufacturing, sintering process precedes blast furnace to prepare feed materials by agglomerating powdered iron ore to form larger particles. There are several techniques which have devised to improve sintering production and productivity including flue gas recirculation(FGR) and additive gas enriched operation. The application of those techniques incurs variations of process configurations as well as inlet and outlet gas conditions such as temperature, composition, and flow rate which exert direct influence on reactions in the bed or the operation of the entire plant. In this study, an approach of sintering bed modeling using flowsheet process simulator was devised in consideration of FGR and the change of incoming and outgoing gas conditions. Results of modeling for both normal and FGR sintering process were compared in terms of outgoing gas temperature, concentration, and moisture distribution pattern as well as incoming gas conditions. It is expected to expand the model for various process configurations with FGR, which may provide the usefulness for design and operation of sintering plant with FGR.

슬러지 유동층 소각로의 프리보드 내 가스 혼합 및 반응 특성에 대한 실험 및 해석적 연구

김영민(Youngmin Kim),신동훈(Donghoon Shin),황승식(Seung-Sik Hwang) 한국연소학회 2011 한국연소학회지 Vol.16 No.4

The present study investigates the combustion phenomena in a sludge incinerator using experimental and numerical method. The temperature and gas concentration were measured at 33 points during operation of the incinerator in order to assess the mixing and combustion characteristics. Numerical simulation was also carried out using a commercial CFD code. Simplified inlet conditions were introduced in oder to predict the bulk solid combustion and the diffusion of the volatile matter released by pyrolysis of sludge. The experimental results showed that the combustion process is extremely inhomogeneous. Large variations were observed in the temperature and gas concentrations in the freeboard of the incinerator due to poor mixing performance between the air and the combustibles, which is caused by massive and bulk generation of volatile matter by fast pyrolysis of sludge particles. The boundary condition of the CFD simulation was found effective in predicting the poor mixing and combustion performance of the reactor.

규모별 순환유동상 보일러의 열설계 변수 비교 평가

김태현(Taehyun Kim),최상민(Sangmin Choi) 한국연소학회 2011 한국연소학회지 Vol.16 No.4

The present paper discusses thermal design parameters of different sizes of circulating fluidized bed (CFB) boilers with capacities ranging from 2 MWe pilot scale boiler to a 600 MWe utility boiler. Physical boiler size and shape of furnace were identified and dimensional data have been summarized. By performing thermal design for each of the boilers, heat transfer surface area, furnace shape and size, and allocation of heat transfer surface for water-steam side heat absorption have been recalculated, and presented. Although boilers may have significantly different capacity, the facilities have common design parameters, when they are evaluated as basic thermal design processes. The significance of thermal design procedure is explicitly discussed.

바이오디젤 혼합연료를 적용한 커먼레일 디젤엔진에서 파일럿 분사에 따른 연소 및 배기 특성

정규수(Kyusoo Jeong),이동곤(Donggon Lee),노현구(Hyun Gu Roh),이창식(Chang Sik Lee) 한국연소학회 2011 한국연소학회지 Vol.16 No.4

The purpose of this study was to analyze the effect of pilot injection strategy on the combustion and emissions characteristics in a four cylinder common-rail direct injection diesel engine fueled with biodiesel(soybean oil) blend. The tested fuel was mixed of 20% biodiesel and 80% ULSD(Ultra low sulfur diesel) by volume ratio. The experiments were performed under two load conditions, and results were compared with those of single injection. The experimental results showed that the ignition delay of BD20 was shorter than compared to that of ULSD in the case of low load condition. Also, the fuel consumption of BD20 was more higher than that of ULSD. Fuel consumption by applied pilot injection strategy were generally decreased compared with that of single injection. In the case of pilot injection, the exhaust emissions such as CO and HC emissions were decreased compared to the single injection.

합성가스의 충돌제트 연소장에서 고신장율 부상 예혼합화염 연소 특성 연구

강기중(Ki-Joong Kang),박태준(Tae-Joon Park),황철홍(Cheol-Hong Hwang),이기만(Kee-Man Lee) 한국연소학회 2011 한국연소학회지 Vol.16 No.4

This paper presents both experimental and numerical investigation of the combustion characteristics of stretched premixed lift-off flames using synthetic gas(H₂/CO) in an impinging burner. We used “Spin code” for numerical analysis. An ICCD camera was employed to measure flame location and flame thickness. The impinging surface temperature was affected by local strain rate K, equivalence ratio, and composition ratio of fuel. In spite of the difference of boundary conditions in experimental and numerical results, the tendencies of surface temperatures were agreed. From result of this work, we also found that flame location and flame thickness directly related to surface temperature are greatly affected by local strain rate K.

고온 고압에서 혼합연료의 층류화염속도 예측 모델에 대한 연구

변정주(Jung Joo Byun) 한국연소학회 2012 한국연소학회지 Vol.17 No.2

Iso-octane, n-heptane and their blends were tested in a constant volume combustion chamber to measure laminar flame speeds. The experimental apparatus was automatically controlled to enhance the accuracy and data acquisition speed. A large database of laminar flame speeds at elevated temperatures and pressures was established. From this database, laminar flame speeds of iso-octane, n-heptane and their blends were investigated and analysed to derive new correlation to predict laminar flame speeds at any blending ratio. The new flame speed model was successfully applied to these fuels with limited range of errors.

부분 예혼합 압축착화 조건에서 디젤분무의 화염특성

방중철(Joong Cheol Bang),박철환(Chul Hwan Park) 한국연소학회 2012 한국연소학회지 Vol.17 No.2

Diesel engines exhaust much more NOx(Nitrogen Oxides) and PM(Particulate Matter) than gasoline engines, and it is not easy to reduce both NOx and PM simultaneously because of the trade-off relation between two components. This study investigated flame characteristics of the partial premixed compression ignition known as new combustion method which can reduce NOx and PM simultaneously. The investigation was performed through the analysis of the flame images taken by a high speed camera from the visible engine which is the modified single cylinder diesel engine. The results obtained through this investigation are summarized as follows; (1) The area of the luminous yellow flame was reduced due to the decrease of flame temperature and even distribution of temperature. (2) The darkish yellow flame zone caused by the shortage of the remaining oxygen after the middle stage of combustion was considerably reduced. (3) Since the ignition delay was shortened, the violent combustion did not occur and the combustion duration became shortened.

IGCC 가스터빈 운전조건에서의 석탄가스 층류화염속도에 대한 기초연구

이정원(Jeongwon Lee),오경택(Kyungtaek Oh),김용모(Yongmo Kim) 한국연소학회 2011 한국연소학회지 Vol.16 No.4

Coal-derived syngas has been utilized by main fuel at IGCC power plant. Research efforts for investigating the characteristics of premixed and nonpremixed flames at gas-turbine condition have been conducted. The present study has been mainly motivated to evaluate the capability of the detailed chemical kinetics to predict the syngas laminar flame speed. Special emphasis is given to the effects of pressure, temperature, syngas composition, and dilution level on the characteristics of premixed and nonpremixed flames. The predicative capability of a number of detailed mechanism for laminar flame speed is compared to experimental data. From these results, detailed kinetics of Davis et al. and Li et al. have the best conformity with the experiments in the all the case of parametric studies.

전산유동해석을 이용한 100MWe급 석탄 순산소 연소 실증 보일러의 설계 및 운전조건 평가

채태영,박상현,홍재현,양원,이상훈,류창국 한국연소학회 2011 한국연소학회지 Vol.16 No.2

As one of the main technologies for carbon capture and storage in power generation, oxy-coal combustion is being developed for field demonstration in Korea. This study presents the results of numerical simulation for combustion in a single-wall-fired 100MWe-scale boiler proposed for the initial design of the demonstration plant. Using a commercial CFD code, the detailed combustion, flow and heat transfer characteristics were assessed both for air-mode and oxy-mode combustion. The results show that stable combustion can be achieved in the dual mode operation with the current boiler configuration. However, the differences in the flow pattern and heat transfer between the two combustion modes need to be considered in the design and operation which is mainly due to the larger density and specific heat of CO₂ compared to N₂. Further development of the boiler design is required using improved numerical modeling for radiative heat transfer and combustion.