• 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.

• Journal of the Korean Society of Combustion
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• v.15 no.2
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• pp.34-40
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• 2010

The effect of co-firing with pulverized coal and wood biomass on ignition and burn-out temperature was investigated at air and oxy-fuel conditions by thermo gravimetric analyzer(TGA). Three kinds of coal(shenhua, adaro, wira) were selected and mixing ratios of coal and wood biomass was set to 1, 0.5, and 0.8. The ignition temperature depended on the amount of volatile matter of blended fuel, while the burn-out temperature was dominated by the oxidant ingredients. The oxy-fuel condition with an oxygen ratio(Ofr,o) of 0.3 showed similar tendency with air condition in the heat flow measurement. Volatile matter reaction, however, became dominant when oxygen ratio exceeded 0.8 for co-firing combustion of wood biomass and pulverized coal.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.12
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• pp.1111-1118
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• 2010

Combustion measurements based on optical techniques have recently become of major interest as tools not only for clarifying the combustion mechanism but also for validating the computational results for the combustion fields. In this study, the particle behavior in turbulent pulverized coal flame are investigated using advanced optical diagnostics. A laboratory-scale pulverized coal combustion burner is specially fabricated as open type in order to apply various optical measurement techniques. The detailed particle behavior is performed by LDV (laser Doppler velocimetry) and SDPA (shadow Doppler particle analyzer). It is observed that the particle mean diameter increase as the distance from burner increases, and this is found to be caused by the decrease of small particles' diameter and increase of large particles' diameter. This is because of result in the char reaction and the particle swelling due to devolatilization, respectively. The size-classified streamwise velocities of pulverized coal particles in the central region of the jet show the same magnitude, whereas those in the outer region are different depending on the particle size. The results show that the velocity and size-classified diameter of the pulverized coal particles in the flame can be measured well by SDPA.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.78.2-78.2
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• 2011

To achieve the required higher efficiency and lower emission performance, Korea's 300 MW IGCC RDD&D (Research Development, Demonstration and Dissemination) project was launched in December 2006 under the leadership of the Korea Electric Power Corporation (KEPCO), with the support of the Korea Ministry of Knowledge Economy. Our research group, KEPCO Research Institute had set-up the a coal gasifier for the pilot test and conducted many experiments for parametric study in this project. Our group focused visualization of pulverized coal injection pattern in the gasifier. Through this study we found that two types of coal burners having different oxygen supply angles can be a source changing gasification condition like temperature.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.155-163
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• 1999

A numerical study for simulating a swirling pulverized coal combustion in axisymmetric geometry is done here by applying the weighted sum of gray gases model (WSGGM) approach with the discrete ordinate method (DOM) to model the radiative heat transfer equation. In the radiative transfer equation, the same polynomial equation and coefficients for weighting factors as those for gas are adopted for the coal/char particles as a function of partial pressure and particle temperature. The Eulerian balance equations for mass, momentum, energy, and species mass fractions are adopted with the standard ${\kappa}-{\varepsilon}$ turbulence model, whereas the Lagrangian approach is used for the particulate phase for soot. The eddydissipation model is employed for the reaction rate for gaseous mixture, and the single-step first-order reaction model for the devolatilization process for coal. By comparing the numerical results with experimental ones, the models used here are confirmed and found to be one of good alternatives for simulating the combustion as well as radiative characteristics.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.11
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• pp.1464-1472
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• 1999

Design and operation of $1MW_{th}$ pulverized coal combustion testing facility are described. Also the influence of air staging on NOx emission and burnout of coal flames was investigated in this facility. The test facility consisted of coal feeding system, firing system and flue gas treatment system. A top-fired externally air staging burner was adopted in order to avoid influence of gravity on the coal particles and for easy maintenance. Distribution of temperature and chemical species concentration of coal flames could be measured in vertical pass of furnace. Main fuel was pulverized (83.4% less than $80{\mu}m$) Australian high bituminous coal. From variety of test conditions, overall excess air ratio was selected at 1.2(20% excess air). Tho study showed that increasing the staged air resulted in lower NOx omission, and it was suggested to be more than 40% of the total combustion air for the substantial NOx reduction. Sufficient burnout was not achievable when NOx emission was less than 500ppm. Also, the amount of core air did not influence tho NOx reduction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.5
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• pp.491-501
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• 2011

We performed numerical simulation using a DPM (discrete phase model) to identify the optimal operation ranges in two representative PM burners widely used in domestic 500-MW pulverized coal-fired power plants. Recently there has been an increased utilization of low-cost coals such as sub-bituminous coal. We investigate the effects of coal blends on the distribution ratio of coal to air by varying the mass flow rates of pulverized coal and primary air and the particle size. We present and discuss optimal conditions for the distribution ratio of coal to air in PM burners.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.1-4
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• 2014

The present work focuses on the analysis of the pulverized coal combustion aerodynamics of the dual swirl burner by the control of the swirl-modes such as the outer swirl intensity (OSI). The detailed structure of pulverized coal swirling flames with swirl-mode was studied experimentally by particle image velocimetry and local flame colors based on $OH^*$, $CH^*$, and ${C_2}^*$ radicals. For all co-swirling conditions, the internal recirculation zone (IRZ) was observed near the inner shear layer with respect to the processing vortex core structure. Furthermore, a co-rotating vortex in the outer shear layer and the exhaust tube vortex (ETV) along the central axis were observed. The intensity of $CH^*$ signal was higher with small coal particle size, conversely, the size of the distribution of the $CH^*$ signal becomes larger. Therefore, the control of the aerodynamics with changing swirl intensities may play an important role in improving both environmental and combustion performances.

• Journal of the Korean Society of Combustion
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• v.4 no.1
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• pp.1-15
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• 1999

In order to analyze the sensitivity on the pulverized coal flames of the several variables, a numerical study was conducted at the gasification process. Eulerian approach is used for the gas phase, whereas lagrangian approach is used for the solid phase. Turbulence is modeled using the standard $k-{\varepsilon}$ model. The turbulent combustion incorporates eddy dissipation model. The radiation was solved using a Monte-Carlo method. One-step two-reaction model was employed for the devolatilization of Kideco coal. In pulverized flame of long liftoff height, the initial turbulent intensity seriously affects the position of flame front. The radiation heat transfer and wall heat loss ratio distort the temperature distributions along the reactor wall, but do not influence the reactor performance such as coal conversion, residence time and flame front position. The primary/secondary momentum ratio affects the position of flame front, but the coal burnout is only slightly influenced. The momentum ratio is a variable only associated with the flame stabilization such as flame front position. The addition of steam in the reactor has a detrimental effect on all the aspects, particularly reactor temperature and coal burnout.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.5
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• pp.1211-1221
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• 1990

The purpose of this study is to get experimental data on the distribution of CWM (Coal- Water Mixture) droplets size and the presence of pulverized coal particles inside CWM droplets. Atomization of CWM is done by Twin-Fluid Atomizer. The operational parameters are atomizing air pressure, coal particle loading, mean size of pulverized coal particles and sampling positions across spray. Th data analysis is initiated by Impression Sampling Method(Magnesium Oxide Technique) and Photo-technique and counting works are followed. Experimental work induces following research results. The variation of particle loadings in slurry makes no appreciable effects on the mean size of CWM droplets. It is evident that atomizing air pressure has very strong effect on the atomization of slurry. The mean size of atomized fuel droplets is dramatically reduced with the increasing air pressure. The population ratio of droplets without coal particles to total number of droplets is decreased as atomizing air pressure or loading rises and the same trend is obtained as the mean size of coal particles becomes smaller but a certain tendency of coal particle presence inside droplets could not be found from the change of sampling positions.