• Journal of the Korean Society of Combustion
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• v.6 no.1
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• pp.20-28
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• 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.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.176-183
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• 2007

An experimental study was performed to investigate the effects of mixing quality, inlet pressure, nozzle diameter on CO emission and radiation characteristics in porous ceramic fiber radiant burners. Observations of combustion characteristics occurring inside the burner system which was insulated fiber mat, were investigated by measuring temperature, CO emission and radiation characteristics. Combustion was achieved at the firing rate of $88{\sim}99$ kcal/hr, inlet pressure of $100{\sim}250$mm$H_2O$. CO emissions were found to be strongly dependent on the operating conditions. There was a tendency that CO concentration increased as the firing rate increases. The reason for rise of CO concentration is that it becomes the relatively rich condition. The fiber burner exhibit significant both spectral intensity peaks in the bands at 2.5${\mu}m$ and 4.0${\mu}m$ relatively, There is a small difference in the variable mixing tube. However spectral intensity increased with the firing rate.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.455-458
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• 2006

This study has numerically modelled the combustion processes of the turbulent swirling premixed lifted flames in the low-swirl burner (LSB). In these turbulent swirling premixed flames, the four tangentially- injected air jets induce the turbulent swirling flow which plays the crucial role to stabilize the turbulent lifted flame. In the present approach, the turbulence-chemistry interaction is represented by the level-set based flame let model. Two-dimensional and three-dimensional computations are made for the various swirl numbers and nozzle length. In terms of the centerline velocity profiles and flame liftoff heights, numerical results are compared with experimental data The three-dimensional approach yields the much better conformity with agreements with measurements without any analytic assumptions on the inlet swirl profiles, compared to the two-dimensional approach. Numerical clearly results indicate that the present level-set based flamelet approach has realistically simulated the structure and stabilization mechanism of the turbulent swirling stoichiometric and lean-premixed lifted flames in the low-swirl burner.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.2
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• pp.270-279
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• 2000

Recently, according to increase in the requirement of electric power, a thermoelectric power plant equipped with pulverized coal combustion system is highly valued, because coal has abundant deposits and a low price compared with others. For efficient use of coal fuel, most of plant makers are studying to improve combustion performance and flame stability, and reduce pollutants emission. One of these studies is how to control the profile of particle injection and velocity dependant on coal nozzle configuration. Basically, nozzle which has mixed flow of gas and particle is required to have the balanced coal concentration at exit, but it is very difficult to obtain that by itself without help of other device. In this study, coal distribution and pressure drop in gas-solid flow are calculated by numerical method in nozzle with various shapes of venturi diffuser as a means to get even coal particle distribution. The tentative correlations of pressure drop and exit coal distribution are deduced as function of the height, length and reducing angle of venturi from the calculated results. When coal hurner nozzle is designed, these equations are very useful to optimize the shape of venturi which minimize uneven particle distribution and pressure drop within coal nozzle.

• 한국연소학회:학술대회논문집
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• 2015.12a
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• pp.291-293
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• 2015

The experimental study on flow characteristic in various laminar coflow diffusion flame has been conducted with a particular focus on the buoyancy force exerted from gaseous hydrocarbon fuels. Methane ($CH_4$), Ethylene ($C_2H_4$) and n-Butane ($C_4H_{10}$) were used as fuels. Coflow burner and Schlieren technique were used to observe the fuel flow field near nozzle exit and flow characteristics in flames. The result showed that the vortices in n-Butane with density heavier than air were appeared near the nozzle exit with the strong negative buoyancy on the fuel stream. As Reynolds number increases by the control of velocity, the vortices were greater and the vortices tips were moved up from the nozzle exit. In addition, it can be found that the heated nozzle can affect to the flow fields of fuel stream near the nozzle exit.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.5
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• pp.1735-1742
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• 1996

An entrained flow gasifier simulating the cold mode was tested to estimate its performance for coal gasification and flow characteristics with a developed high speed impinging jet nozzle. The burner was designed for high temperature and high pressure(HTHP) conditions, especially for IGCC(Integrated Coal Gasification Combined Cycle). In order to get proper size of droplets for high viscous liquid such as coal slurry, atomization was achieved by impacting slurry with high speed (over 150m/sec) secondary gas (oxygen/or air)/ Formed water droplets were ranged between 100.mu.m to 20.mu.m in their sizes. The flow characteristics in the gasifier was well understood in mixing between fuel and oxidizer. Both external and internal recirculation zones were closely investigated through experimentation with visualization and numerical solutions from FLUENT CODE.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2204-2209
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• 2008

Flame pattern in burner used in steel industry that constitutes 30% of country energy consumption is generally characterized as long narrow flame pattern so that localized heating causes product quality worse and many burners are needed for proper heating. This paper deals with flat wide flame pattern which has advantage in terms of uniform heating using less number of burners. For that purpose, impinging jet system of fuel and oxidant was used for making flat wide flame. Results show that nozzle angle $75^{\circ}$ of impinging jet is found to be optimum configuration for making effective wide flame which has uniform radiation heat transfer and flame temperature is also most uniform along the flame width for that nozzle angle.

• Journal of Hydrogen and New Energy
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• v.23 no.5
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• pp.493-502
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• 2012

Syngas laminar burning velocity measurements were carried out at atmospheric pressure and ambient temperature using the Bunsen flame configuration with nozzle burner as a fundamental study on flame stability of syngas fuel. Representative syngas mixture compositions ($H_2$:CO) such as 25:75%, 50:50% and 75:25% and equivalence ratios from 0.5 to 1.4 have been conducted. Average laminar burning velocities have been determined by the stabilized nozzle burner flames using the angle method, radical surface area method and compared with the data obtained from the other literatures. And the results of each experimental methodologies in the various composition ratios and equivalence ratios were coincided with the result of numerical simulation. Especially, it was confirmed that there was necessary to choice a more accurate measurement methodology even the same static flame method for the various composition ratios of syngas fuel including hydrogen. Also, it was reconfirmed that the laminar burning velocities gradually increased with the increasing of hydrogen content in a fuel mixture.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.81-88
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• 2002

It's well known that with the increase of preheated air temperature NOx is increasing ,while the energy consumption is decreasing. In this study the experimental study was carried out to find out a new method breaking the above-mentioned old concept. From the variation of configuration of gas nozzle and hot test on the temperature distribution and NOx, it was found out that the reduction of NOx was due to the effect of internal gas recirculation, which will be caused by air emitting velocity from burner nozzle.

• 한국연소학회:학술대회논문집
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• 2006.04a
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• pp.128-134
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• 2006

A characterization of turbulent reacting flows has proved difficult owing to the complex interaction between turbulence, mixing, and combustion chemistry. There are many types of time scales in turbulent flame which can determine flame structure. This counter jet type premixed burner produces high intensity turbulence. The goal is to gain better insights into the flame structures at high turbulence. 6 propane/air flames gave been studied with high velocity fluctuation in bundle type nozzle and in one hole type nozzle. By measuring velocity fluctuation, turbulent intensity and integral length scale are obtained. And sets of OH LIF images were processed to see flame structure of the mean flame curvatures and flame lengths for comparison with turbulence intensity and turbulent length scales. The results show that the decrease in nozzle size generates smaller flow eddy and mean curvatures of the flame fronts, and a decrease in Damkohler number estimated from flow time scale measurement.