• 에너지공학
• /
• 제25권4호
• /
• pp.152-158
• /
• 2016

연소기기에서 연소반응과정이 일어날 때 연소로 내 고온의 온도 분위기에서 공기 중의 산소와 질소가 반응하여 질소산화물이 발생하게 된다. 발생한 질소산화물을 저감하기 위하여 화력발전소나 폐기물 소각로는 촉매를 이용한 탈질설비를 설치하고 있는데 이에 따른 설치와 유지비용이 많이 소요된다. 연소기기에서 질소산화물을 저감하기 위한 여러 가지 방법 중에 배기가스 재순환 방법이 널리 쓰이고 있다. 본 연구에서는 배기가스 재순환 배관에 코안다 노즐을 사용하여 배기가스를 재순환하는 재순환 버너에 대하여 전산유체해석을 통해 연구를 수행하였으며 냉간 유동에서 배기가스 재순환 유동 특성을 살펴보았고 코안다 노즐의 공기 측 간격 변화와 공기 유량 변화에 따른 배기가스 재순환 유량 특성을 살펴보았다. 본 연구의 버너 형상은 배기가스 재순환 흡입구와 출구는 원통 버너의 중심을 향하지 않고 접선 방향으로 설치되어 있어서 버너 내부에서 선회 유동이 형성 되었으며 이에 따라 원통 내부의 중심부분에 역류가 일어나는 특성을 관찰하였다. 또한, 코안다 노즐의 공기 측 간격은 0.5mm일 때는 배기가스 재순환 유량이 공기량 보다 약 2.5배 이었고 1.0mm일 때는 약 1.5배로 나타났으며 같은 공기 측 간격에서 공기량을 증가하면 배기가스 재순환 유량은 약간 증가하는 것을 알 수 있었다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2001년도 제23회 KOSCO SYMPOSIUM 논문집
• /
• pp.17-26
• /
• 2001

Self flue gas recirculation flow is an effective method for low NOx emission in the regenerative low NOx burner. The object of this study is to analyze the self flue gas recirculating flow by varying jet velocity of the combustion air. Fuel and air flow rates are fixed and combustion air jet nozzle diameters are 13, 6.5 and 5mm. The stoichiometric line is obtained from the concentration of the fuel using an acetone PLIF technique. It is found that the self flue gas recirculating flow is entrained into that line using a two color PIV technique. As the jet velocity of combustion air is increased, the flue gas entrainment rate into the stoichiometric line is increased. This result suggests that NOx emission can be reduced due to the effects of flue gas which is lowering the flame temperatures.

• 한국연소학회지
• /
• 제6권1호
• /
• pp.20-28
• /
• 2001

Self flue gas recirculation flow is an effective method for low NOx emission in a regenerative low NOx burner. The object of this study is to analyze self flue gas recirculating flow by varying the jet velocity of the combustion air. Fuel and air flow rates are fixed and combustion air jet nozzle diameters are 13, 6.5 and 5mm. The stoichiometric line is obtained from the concentration of fuel using the acetone PLIF technique. It is found that self flue gas recirculating flow is entrained into that line using the two color PIV technique. As the jet velocity of combustion air is increased, the flue gas entrainment rate into the stoichiometric line is increased. This result suggests that NOx emission can be reduced due to the effects of flue gas lowering the flame temperature.

• 한국가스학회지
• /
• 제22권3호
• /
• pp.7-12
• /
• 2018

화석연료를 연소할 때 연소로 내의 고온의 온도 분위기에서 열적 질소산화물이 발생하게 된다. 연소기기에서 질소산화물을 저감하기 위한 여러 가지 방법 중에 배기가스 재순환 방법이 널리 쓰이고 있다. 본 연구에서는 배기가스 재순환 배관에 코안다 노즐을 사용하고 양쪽 출구가 트인 재순환하는 버너에 대하여 냉간 유동 특성을 전산유체해석을 통해 살펴보았다. 재순환 배관이 원통 버너의 접선방향으로 설치되어 있어서 버너 내부에서 선회유동이 형성되어 원통 버너 중심 부분에 역류가 생기는 현상을 관찰하였으며 이는 한쪽이 막힌 재순환 버너와 유사한 경향임을 확인 하였다. 본 연구로부터 양쪽 출구가 트인 재순환 버너에서 재순환 유입량은 한쪽이 막힌 버너보다 약 5% 증가하는 것을 확인하였고 양쪽 트인 버너에서 배기가스 재순환 배관의 유입구 위치의 출구에서는 전체 영역에서 유입 유동이 형성되고 반대편의 출구에서는 총 유량은 배출되지만 원통의 가운데 부분은 역류가 일어나는 것을 확인하였다. 배출되는 출구에서 배출되는 유량은 유입되는 출구에서의 유입량보다 3~5배 유량이 크게 나타났다.

• 한국연소학회지
• /
• 제8권1호
• /
• pp.17-24
• /
• 2003

The conventional regenerative system has a high thermal efficiency as well as energy saving using the high preheated combustion air. in spite of these advantages, it can not avoid high nitric oxide emissions. Recently, flameless combustion has received much attention to solve these problems. In this research, numerical analysis is performed for flow-combustion phenomena in the self regenerative burner. In this analysis we used Fluent 6.0 code. the that is developed for commercial use, Methane gas is used as a fuel and two-step reaction model for methane and Zeldovich mechanism for NO generation are used. the velocity of the preheated combustion air is used as a parameter and we analyze the characteristics of flow-field, temperature distributions and NO emissions. Due to the increased recirculation rate, the maximum temperature of flame is significantly increased and NOx emissions is reduced.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2002년도 제25회 KOSCI SYMPOSIUM 논문집
• /
• pp.97-104
• /
• 2002

The conventional regenerative system has a high thermal efficiency as well as energy saving using the high preheated combustion air. in spite of these advantages, it can not avoid high nitric oxide emissions. Recently, flameless combustion has received much attention to solve these problems. In this research, numerical analysis is performed for flow-combustion phenomena in the self regenerative burner. In this analysis we used Fluent 6.0 code. the that is developed for commercial use, Methane gas is used as a fuel and two-step reaction model for methane and Zeldovich mechanism for NO generation are used. the velocity of the preheated combustion air is used as a parameter and we analyze the characteristics of flow-field, temperature distributions and NO emissions. Due to the increased recirculation rate, the maximum temperature of flame is significantly increased and NOx emissions is reduced

• 한국연소학회지
• /
• 제12권4호
• /
• pp.22-30
• /
• 2007

The NOx emission characteristics were studied in an oscillating combustion burner equipped with a specially designed proportioning valve. The effects of various parameters on the NOx emission which are important in oscillating combustion were investigated. Also, the effects of coincident application of flue gas recirculation(FGR) were evaluated. The results show that oscillating combustion is an efficient tool for reducing NOx in the burner. Up to 53% of NOx reduction could be acquired in low frequency and small duty ratio conditions. The coincident application of FGR further reduced the NOx emission up to 74%. Thus, this study assured that oscillating combustion technology with FGR could be a fascinating method for NOx reduction in industrial burners.

• 대한기계학회논문집B
• /
• 제32권10호
• /
• pp.729-753
• /
• 2008

Oxy-fuel combustion is a reliable way for the reduction of pollutants, the higher combustion efficiency and the separation of carbon dioxide. The review of recent research trends and the prospects of oxy-fuel combustion were presented. The difference in characteristics among oxy-fuel combustion, conventional air combustion, oxy-fuel combustion with flue gas recirculation (FGR) technique was investigated. Recent experiments of oxy-fuel combustion with/without FGR were surveyed in various ways which are optimized burner design, flame characteristics, the soot emission, the radiation effect, the NOx reduction and the corrosion of combustor. Numerical simulation is more important in oxy-fuel combustion because flame temperature is so high that conventional measurement devices have a restricted application. Equilibrium and non-equilibrium chemical reaction mechanisms for oxy-fuel combustion were investigated. Combustion models suitable for the numerical simulation of non-premixed oxy-fuel flame were surveyed.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2009년 춘계학술대회논문집
• /
• pp.329-334
• /
• 2009

An oxy-fuel boiler has been developed to capture $CO_2$ from the exhaust gas. FGR (flue gas recirculation) is adopted to be compliant with the retrofit scenario. Numerical simulations have been performed to study the detailed physics inside the combustion chamber of the boiler. The temperature field obtained from the simulation agrees with the flame image from the experiment. The FGR combustion yields similar heat transfer characteristics with the conventional air combustion while the flame is formed further downstream in case of the FGR combustion.

• 한국연소학회지
• /
• 제16권3호
• /
• pp.12-20
• /
• 2011

Oxy-coal combustion for $CO_2$ capture in coal power plants entails a mode switching from air-firing to oxyfiring. In this study, procedure of the mode switching was investigated and discussed through experiments in pilot scale facilities: (1) a 0.3 $MW_{th}$ furnace with a vertical single burner and a FGR(Flue Gas Recirculation) system (2) a 1 $MW_{th}$ furnace with horizontal 4 burners and a FGR system. Principle of the mode switching was established and performed with control of FD fan, FGR fan, ID fan and oxygen flow rates. We have found that equivalence ratio in the oxy-firing mode should be increased more than that in the air-firing to achieve stable mode switching. Control of FD, ID and FGR fans should be performed carefully in the mode switching, in the sense of complete combustion and flame attachment. Moisture contents in the ash and the flue gas recycled to the primary oxidizer stream should be removed to prevent condensation, corrosion and duct clogging.