• Journal of the Korean Society of Combustion
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• v.13 no.1
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• pp.31-43
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• 2008

Oxy-fuel flame has a significantly different structure from that of air-fuel flame because of its high temperature. This study is aimed to find out the difference of the oxy-fuel flame structure in order to understand reaction mechanism closely, which is crucial to design real-scale oxy-fuel combustion system. By examining pictures of counterflow flame and LIF images, we found that oxy-fuel flame had two-zone structure: fuel decomposition region and distributed CO oxidation region. In the oxy-fuel flame, OH radical was distributed intensely through the whole flame due to its higher flame temperature than crossover temperature. For showing those features of the oxy-fuel flame, 1 MW scale IFRF oxy-natural gas burner was simulated by conditional moment closure(CMC) model. Calculation results were compared with experimental data, and showed agreements in trend. In the simulated distributions of fuel decomposition/CO oxidation rates, CO oxidation region was also separated from fuel decomposition zone considerably, which showed the two-zone structure in the oxy-fuel flame.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.69-74
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• 2006

An Experimental study was conducted on $CO_2$ recycle combustion heating system using pure oxygen instead of conventional air as an oxidant, which is thereby producing a flue gas of mostly $CO_2$ and water vapor($H_2O$) and resulting in higher $CO_2$ concentration. The advantages of the system are not only the ability to control high temperatures characteristic of oxygen combustion with recycling $CO_2$. but also the possibility to reduce NOx emission in the flue gas. A small scale industrial reheating furnace simulator and specially designed variable flame burner were used to characterize the $CO_2$ recycle oxy-fuel combustion, such as the variations of furnace pressure, temperature and composition in the flue gas during recycle. It was found that $CO_2$ concentration in the flue gas was about 80% without $CO_2$ recycle, but increased to $90{\sim}95%$ with $CO_2$ recycle. The furnace temperature and pressure was decreased due to recycle and the NOx emission was also reduced to maintain under 100ppm.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.57-64
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• 2002

This paper describes the results of a series of experiments executed by using two pilot-scale oxv-fuel burners are designed for maximum capacity of 50,000 kacl/hr, 300,000 kcal/hr and installed in the test furnace. The effects of turn-down ratio, excess oxygen ratio, nozzle exit velocity, injection angle, swirl vane angle and inlet oxygen temperature on the combustion characteristic are investigated. Temperature distributions are measured using R-type and Molybdenum sheathed C-type thermocouple. The results showed that maximum temperature and mean temperature increase with the increase of turn-down ratio and inlet oxygen temperature. The maximum flame temperature was increased about 35% compared to the case of equivalent air operated condition. In addition, Optimum excess oxygen ratio and nozzle characteristics are obtained for this oxy-fuel glass melting furnace.

• 한국연소학회:학술대회논문집
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• 2013.06a
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• pp.121-122
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• 2013

In recent years, the usage of fossil fuels has caused problems of climate change and global warming. Because the combustion of fossil fuels is related to the production of greenhouse gases ($CO_2$, $CH_4$, etc.), new technology in the field of combustion is needed in order to handle the crisis of climate change and the global warming. As one of the efforts to reduce the emission of greenhouse gases, the concept of regenerative oxy-fuel combustion for energy efficiency and carbon capture was suggested, In the current study, the development of an industrial regenerative oxy-fuel combustion furnace was introduced, which has been being performed at Korea Institute of Energy Research (KIER).

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.329-334
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• 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.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1019-1024
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• 2008

A 3 MW class oxy-fuel boiler has been developed to capture $CO_2$ from the exhaust gas. The system is a scale-up of the previous 0.5 MW class system in general. A heat exchanger and a mixer are additionally installed to stabilize the flame for the FGR mode. The system yields the exhaust gas with $CO_2$ concentration over 90% and reduced NO emission to 1/10 of conventional air combustion system.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.123-123
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• 2014

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.121-121
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• 2015

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.409-416
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• 2010

The use of oxy-fuel combustion and flue gas recirculation (FGR) for $CO_2$ reduction has been studied by many researchers. This study focused on the characteristics of oxy-fuel combustion and the effects of $CO_2$ addition from the point of view of oxygen feeding ratio (OFR) and the position of $CO_2$ addition in order to reproduce an FGR system with a triple concentric multi-jet burner. Oxy-fuel combustion was stable at all OFRs at a fuel flow-rate of 15 lpm, which corresponds to an equivalence ratio of 0.93; however, the structure and length of the flame varied at different OFRs. When $CO_2$ was added in oxy-fuel combustion, various stability modes such as stable, transient, quasistable, unstable, and blow-out were observed. The temperature in the combustion chamber decreased upon $CO_2$ addition in all conditions, and the maximum reduction in temperature was below 1800 K. $CO_2$ concentration with respect to height varied with the volume percent of $CO_2$ at the nozzle tip.

• Journal of the Korean Society of Combustion
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• v.21 no.4
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• pp.39-47
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• 2016

The aims of this research were to investigate combustion characteristics of lab-scale pressurized oxy-fuel combustion(POFC) system. In this study, the reactor, 800 mm long, was equipped with co-axial burner. Low calorific value syngas that is composed of mainly CO and $H_2$ was used as fuel whereas pure oxygen was used as an oxidant. Thermal heat input to the reactor varied from 2.6 kW to 6.1 kW. The reactor pressure also increases from atmospheric up to 15 bar. The results show that as the pressure increase, the temperature of reactor decreases on the whole in all cases. A significant temperature drop was observed especially at the bottom section of the reactor that exist flame. In addition, the flame instability increases as the pressure increases. Furthermore $NO_x$ emissions increases from atmospheric up to 2 bar. However beyond 2 bar, $NO_x$ emission reduces as pressure increases. Lastly $NO_2$ ratio in $NO_x$ also increases as pressure increases.