• 한국항공우주학회지
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• 제41권8호
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• pp.639-648
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• 2013

본 논문은 부게넘 및 태안 IGCC플랜트의 연료를 대상으로 석탄으로부터 생성된 합성가스의 NOx/CO배출 특성, 온도특성, 화염의 구조에 대해 기술하였다. GE7EA 모사 가스터빈 연소기를 대상으로 상압 고온 연소시험을 수행하여 입열량 및 질소희석에 따른 연소특성을 관찰하였다. 입열량이 감소하고, 희석제량이 증가할 때 단열화염온도의 감소로 NOx가 감소하였고, 저부하에서는 희석량이 증가할수록 불완전 연소로 인해 CO가 증가하였다. 이러한 NOx 감소 및 CO발생은 각각 $1500^{\circ}C$ 와 $1250^{\circ}C$의 특정 화염온도에서 관찰되었다. 또한 질소 희석이 증가할수록 단열화염온도 및 연소기 라이너의 온도가 감소했고, 화염 부상과 같은 화염구조의 변화로 인해 특이점이 관찰되었다. 본 연구결과를 통해 질소희석이 NOx/CO배출 및 온도, 화염구조에 미치는 영향이 검토되었으며, 시험 데이터는 향후 태안 IGCC 플랜트의 운전시 최적 조건 선정을 위한 기초자료로 활용될 예정이다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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• pp.185-191
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• 2002

The influence of N2 addition on soot formation, flame temperature and NOx emissions is investigated experimentally with methane fuel co-flow diffusion flames. The motivation of the present investigation is the differences in NOx reduction reported between fuel-side and oxidizer-side introduction of N2. To determine the influence of dilution alone, fuel was diluted with nitrogen while keeping the adiabatic flame temperature fixed by changing the temperature of the reactants. And to see the thermal effect only, air was supplied at different temperature without N2 addition. N2 addition into fuel side suppressed the soot formation than the case of oxidizer-side, while flame temperature enhanced the soot formation almost linearly. These results reveals the relative influences of the thermal, concentration effects of N2 additives on soot formation In accordance with experimental study, numerical simulation using CHEMKIN code was carried out to compare the temperature results with those acquired by CARS measurement, and we could find that there is good agreement between those results. Emission test revealed that NOx emissions were affected by not only flame temperature but also N2 addition.

• 대한기계학회논문집B
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• 제33권7호
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• pp.486-494
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• 2009

One-dimensional modeling of $CH_4$/air premixed flame was conducted to validate the heat loss model and investigate NOx formation characteristics in the postflame region. The predicted temperature and NO concentration were compared to experimental data and previous heat loss model results using a constant gradient of temperature (100 K/cm). The following conclusions were drawn. In the heat loss model using steady-state heat transfer equation, the numerical results using the effective heat loss coefficient ($h_{eff}$) of $1.0\;W/m^2K$ were in very good agreement with the experiments in terms of temperature and NO concentration. On the other hand, the calculated values using the constant gradient of temperature (100 K/cm) were lower than that in the experiments. Although the effects of heat loss suppress NO production near the flame region, a significant difference in NO concentration was not found compared to that under adiabatic conditions. In the postflame region, however, there were considerable differences in NO emission index as well as the contribution of NO formation mechanisms. In particular, in the range of ${\phi}\;{\geq}\;0.8$, the prompt NO mechanism plays an important role in the NO reduction under the adiabatic condition. On the other hand, the mechanism contributes to the NO production under the heat loss conditions.

• 한국수소및신에너지학회논문집
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• 제30권6호
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• pp.593-600
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• 2019

The combustion characteristics of methane/hydrogen pre-mixed flame have been investigated with swirl stabilized flame in a laboratory-scale pre-mixed combustor with constant heat load of 5.81 kW. Hydrogen/methane fuel and air were mixed in a pre-mixer and introduced to the combustor through a burner nozzle with different degrees of swirl angle. The effects of hydrogen addition and swirl intensity on the combustion characteristics of pre-mixed methane flames were examined using particle image velocimetry (PIV), micro-thermocouples, various optical interference filters and gas analyzers to provide information about flow velocity, temperature distributions, and species concentrations of the reaction field. The results show that higher swirl intensity creates more recirculation flow, which reduces the temperature of the reaction zone and, consequently, reduces the thermal NO production. The distributions of flame radicals (OH, CH, C₂) are dependent more on the swirl intensity than the percentage of hydrogen added to methane fuel. The NO concentration at the upper part of the reaction zone is increased with an increase in hydrogen content in the fuel mixture because higher combustibility of hydrogen assists to promote faster chemical reaction, enabling more expansion of the gases at the upper part of the reaction zone, which reduces the recirculation flow. The CO concentration in the reaction zone is reduced with an increase in hydrogen content because the amount of C content is relatively decreased.

• 대한기계학회논문집B
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• 제22권4호
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• pp.468-480
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• 1998

The temporal and spatial distributions of soot volume fractions were measured for single toluene droplet flames as a function of pressure under the normal-gravity condition. In order to characterize the transient nature of the flame and sooting regions, a full-field light extinction and subsequent tomographic inversion technique was used. The reduction in sooting as a function of pressure was assessed by comparison of the maximum soot volume fractions at several vertical positions along the axis above the droplet. The maximum soot volume fraction was reduced by 70% when the pressure was reduced by 60% from 1 atm to 0.4 atm. The reduction in sooting is attributed to variation of the geometric configuration of flame which reduces the system Grashof number as well as only the change in the adiabatic flame temperature as the pressure decreases. The gravimetrically-measured total soot yield was also compared to the optically-measured soot volume fraction to obtain a correlation between the two measurements. As a result, the total soot yield was linearly proportional to the optically-measured maximum soot volume fraction and linearly reduced as the pressure decreased. Accordingly, the non-intrusive full-field light extinction-measurements were able to be calibrated not only to measure soot volume fraction, but to simultaneously evaluate the total soot yield emitted from the toluene droplet flame (which is useful in the practical application).