• 대한기계학회논문집B
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• 제28권2호
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• pp.207-214
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• 2004

The burning velocities of conventional and oxygen-enriched methane flame in various equivalence ratio were determined by experiments. The validity of existing reaction mechanisms was examined in oxygen-enriched flame on the basis of the experiment results. Modified reaction mechanism is suggested, which was able to predict burning velocity of oxygen enriched flame as well as methane-air flame. Complementary study on reaction mechanisms shows the following results : Present experiment data were found to be more reliable in comparison with existing ones in a oxygen-enrichment condition. It was found that some modification in existing reaction mechanisms is necessary, since discrepancy between measurements and predictions is increasing with oxygen enrichment ratio. The sensitivity analysis was performed to discriminate the dominantly affecting reactions on the burning velocity in various oxygen enrichment and equivalence ratio. A modified GRI 3.0 reaction mechanism based on our experiment results was suggested, in which reaction rate coefficients of (R38) H+O$_2$<=>O+OH in GRI 3.0 reaction mechanisms were corrected based on sensitivity analysis results. This mechanism showed a good agreement in predicting the burning velocity and number density of NO in oxygen-enriched flame and would provide proper reaction information of oxygen-enriched flame at this stage.

• 한국연소학회지
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• 제12권4호
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• pp.14-21
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• 2007

In order to enhance combustion efficiency, oxygen-enriched combustion is used by increasing the oxygen ratio in the oxidizer. However, since the flame temperature increases, NOx formation in the furnace seriously increases for low oxygen enrichment ratio. In this case, reburning is a useful technology for reducing nitric oxide. In this research, experimental studies have been conducted to evaluate the hybrid effects of reburning/selective non-catalytic reaction (SNCR) and reburning/air staging on NOx formation and also to examine heat transfer characteristics in various oxygen-enriched LPG flames. Experiments were performed in flames stabilized by a co-flow swirl burner, which were mounted at the bottom of the furnace. Tests were conducted using LPG gas as main fuel and also as reburn fuel. The paper reported data on flue gas emissions, temperature distribution in furnace and various heat fluxes at the wall for a wide range of experimental conditions. Overall temperature in the furnace, heat fluxes to the wall and NOx generation were observed to increase by low level oxygen-enriched combustion, but due to its hybrid effects of reburning, SNCR and Air staging, NOx concentration in the exhaust have decreased considerably.

• 대한기계학회논문집B
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• 제28권1호
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• pp.9-15
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• 2004

$CO_2$ is a well-known green house gas as well as the major source of global warming. Many researchers have studied to reduce $CO_2$ emission in combustion processes. Among the method for reducing $CO_2$ emission, oxygen-enriched combustion has been proposed. Because its adiabatic flame temperature is relatively too high, existing facilities must be changed or the flame temperature in the combustion zone should be reduced. The combustion characteristics, composition in the flame zone, temperature profile and emission gases were investigated experimentally for the various oxygen-enriched ratios(OER) by the addition of $CO_2$, under constant $O_2$ flow rate. Results showed that the reaction zone was quenched and broadened as the addition of $CO_2$ was increased. The emission of NOx in flue gas was decreased as decreasing temperature in reaction zone. It was also shown that the reaction was delayed by the cooling effect. As the addition of $CO_2$ was increased, the composition of CO in the flame zone was increased due to the increase of reaction rate by increasing mixing effect of oxidant/fuel at OER=0％, but the composition of CO was decreased by quenching effect at OER=50％ and 100％.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1389-1394
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• 2003

$CO_2$ is a well-known green house gas, which is the major source of global warming. Many researchers have studied to reduce $CO_2$ emission in combustion processes. Among the method for reducing $CO_2$ emission, oxygen-enriched combustion has been proposed. But the adiabatic flame temperature is too high. So existing facilities must be changed, or the adiabatic flame temperature in the combustion zone should be reduced. The combustion characteristics, composition in the flame zone, temperature profile and emission gases were studied experimentally for the various oxygen-enriched mtios(OER) by addition of $CO_2$ under coustant $O_2$ flowrate. Results showed that the reaction zone was quenched, broadened, as addition of $CO_2$ was increased. Temperature has a large effect on the NOx emission. The emission of NOx in flue gas decreased due to the decreased temperature of reaction zone. It was also shown that the reaction was delayed by the cooling effect. As the addition of $CO_2$ was increased, the composition of CO in the flame zone increased due to the increase of reaction rate by increasing mixing effect of oxidant/fuel at OER=0, but the composition of CO decreased by quenching effect at OER=50 and 100%.

• 한국연소학회:학술대회논문집
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• 한국연소학회 제26회 KOSCO SYMPOSIUM 논문집
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• pp.261-266
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• 2003

An experimental study has been conducted to evaluate the effects of $CO_{2}$ on heat transfer from hydrogen oxygen-enriched flame. Experiments were performed on flames stabilized by a co-flow swirl burner, which mounted on top of the furnace. Five composition conditions of oxidizer were chosen with replacing $N_{2}$ with $CO_{2}$. In a steady state, total and radiative heat flux rates from the flame to the wall of furnace has been measured using heat flux meters. Temperature distribution in furnace also has been checked. Increasing $CO_{2}$ ratio in the oxidizer, the dominant heat transfer mode was changed into convection from radiation. Temperature in the furnace decreased but total heat flux increased.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.238-244
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• 2005

This study performs the pilot-plant experiments to evaluate the effect of the oxygen enrichment on the co-incineration of municipal solid waste and organic sludge from a wastewater treatment facility. The design capacity of the stoker-type incinerator pilot-plant is 150 kg/h. Combustion chamber temperatures were measured as well as the stack gas concentrations, i.e., NOx, CO, and the residual oxygen. The maximum ratio of organic sludge waste to the total waste input is 30%. Also the oxygen-enriched air with 23% of oxygen in supplied air is used for stable combustion. As the co-incineration ratio of the sludge increased up to 30% of the total waste input, the primary and the secondary combustion chamber temperature was decreased $to900^{\circ}C$ (primary combustion chamber), $750^{\circ}C$(secondary combustion chamber), respectively, approximately $200^{\circ}C$ below the incineration temperature of the domestic waste only (primary: $1,100^{\circ}C$, secondary: $950^{\circ}C$). However, if the supplied air was enriched to 22% oxygen content in air, the incinerator temperature was high enough to burn the waste mixture with 30% sludge, which has the heating value of 1,600 kcal/kg.

• 한국대기환경학회지
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• 제23권5호
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• pp.557-562
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• 2007

The purpose of this paper is to investigate the reforming characteristics and maximum operating condition for the hydrogen production by methane reforming using the compression ignition engine induced partial oxidation. An dedicated compression engine used for methane reforming was decided operating range. The partial oxidation reforming was investigated with oxygen enrichment which can improve hydrogen production, compared to general reforming. Parametric screening studies were achieved as $O_2/CH_4$ ratio, total flow rate, and intake temperature. When the variations of $O_2/CH_4$ ratio, total flow rate, and intake temperature were 1.24, 208.4 L/min, and $400^{\circ}C$, respectively, the maximum operating conditions were produced hydrogen and carbon monoxide. Under the condition mentioned above, synthetic gas were $H_2\;22.77{\sim}29.22%,\;CO\;21.11{\sim}23.59%$.

• 한국광학회지
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• 제15권1호
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• pp.1-5
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• 2004

분리막을 이용한 산소-18 분리실험에서 분리된 시료의 동위원소 성분비 분석을 위해 다이오드 레이저 흡수분광장치를 구성하였다. 흡수신호의 신호 대 잡음비를 높이기 위해 lock-in증폭기를 사용한 파장변조 분광법을 채택하였다. 레이저의 주파수 변조폭 최적화와 FFT 저역통과 필터링을 통해 다중반사흡수셀에서 발생하는 간섭무늬 잡음을 줄였다. 산소-18에 대한 흡수분광장치의 최대편차는 $\pm$4$\textperthousand$로 측정되었다.

• 암석학회지
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• 제26권4호
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• pp.311-325
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• 2017

백두산 지역 중기 마이오세 알칼리현무암에 포획된 페리도타이트 포획암은 주로 첨정석 레졸라이트로 조립질의 원생입상 조직을 보인다. 이 포획암들은 감람석을 치환하는 이차기원의 사방휘석과 감람석 결정입자의 경계를 따라 멜트(즉, 유리)를 산출하고 있다. 백두산 페리도타이트 포획암의 감람석, 사방휘석 그리고 단사휘석은 높은 Mg#(90~92), 첨정석의 Cr#는 11~29를 나타낸다. 백두산 페리도타이트 포획암의 주성분원소 성분은 심해 페리도타이트의 특성을 나타낸다. 단사휘석은 불호정성 미량원소에 부화되어 있으며, 두 종류의 미량원소 패턴을 보여준다.: (1) 경희토류원소가 결핍된 형태($(La/Yb)_N=0.1{\sim}0.2$, $(La/Ce)_N=0.4{\sim}0.8$). (2) 경희토류원소가 부화된 형태($(La/Yb)_N=2.2{\sim}3.8$, $(La/Ce)_N=1.2{\sim}1.6$). 계산된 평형 온도와 산소 분압은 각각 $920{\sim}1050^{\circ}C$와 ${\Delta}fO_2(QFM)=-0.8{\sim}0.2$이다. 백두산 페리도타이트 포획암들은 최대 15% 정도의 마그마를 만들고 난 후 맨틀에 남아있는 잔류 암석으로, 그 이후 실리카와 경희토류원소에 부화된 유체(혹은 멜트)에 의해 다양한 정도의 모달/은폐 교대작용을 경험하였음을 반영하고 있다.

• 한국지열·수열에너지학회논문집
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• 제18권4호
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• pp.12-21
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• 2022

Steam assisted gravity drainage(SAGD) is a process that drills well in the underground oil sands layer, injects hightemperature steam, lowers the viscosity of buried bitumen, and recovers it to the ground. Recently, direct contact steam generator(DCSG) is being developed to maximize steam efficiency for SAGD process. The DCSG requires high technology to achieve pressurized combustion and steam generation in accordance with underground pressurized conditions. Therefore, it is necessary to develop a combustion technology that can control the heat load and exhaust gas composition. In this study, process analysis of high-pressurized DCSG was conducted to apply oxygen enrichment technology in which nitrogen of the air was partially removed for increasing steam production and reducing fuel consumption. As the process analysis conditions, methane as the fuel and normal air or oxygen enriched air as the oxidizing agent were applied to high-pressurized DCSG process model. A simple combustion reaction program was used to calculate the property variations for combustion temperature, steam ratio and residual heat in exhaust gas. As a major results, the steam production efficiency of DCSG using the pure oxygen was about 6% higher than that of the normal air due to the reducing nitrogen in the air. The results of this study will be used as operating data to test the demonstration device.