• Journal of the Korean Society of Combustion
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• v.19 no.3
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• pp.1-7
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• 2014

Experimental study has been carried out to understand combustion characteristics of a swirl-stabilized premixed gas turbine combustor for power generation. $NO_x$ and CO emissions, extinction limit, pressure loss, and temperature distribution were measured for various operating conditions. Results show that, with increasing inlet air temperature, $NO_x$ is increased due to a higher adiabatic flame temperature while CO is increased or decreased for low or high A/F ratio regime, respectively. depending on the flame location. With decreasing load from the design condition, $NO_x$ is decreased as thermal load is reduced. With further decreasing load, however, $NO_x$ is increased due to a longer residence time. CO is decreased and then increased with decreasing load. Flame extinction limit is extended with increasing inlet air temperature as the recirculation strength is enhanced.

• Journal of the Korean Society of Combustion
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• v.12 no.4
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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.

• Journal of Power System Engineering
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• v.18 no.5
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• pp.35-41
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• 2014

The wood pellet, which is one of the woody biomass energy, has very high economic efficiency and combustion efficiency during their combustion. The existing pellet burner have many problems such as low combustion efficiency, flame stabilization, ash problem and ignition time etc. We developed cyclonic wood pellet burner aim to 20,000kcal/hr boiler and measured temperature profiles and exhaust gases in order to investigate the flame stability and optimum combustion condition at any air flow conditions. As results, we confirmed the reappearance and the isotropy of the experimental results in the burner. At the first air flow inlet condition of excess air ratio ${\alpha}=0.02$, second air flow $490{\ell}/min$ had the best combustion condition when pellet supplied 30g. This result means that we need much air supply only for the swirling of second air flow. So we tested various second air flux at first air excess air ratio ${\alpha}=0.7$ condition. At this condition, we could find out that we don't need much second air and total air flux compared to the former condition. We will continuously test this work of air flow distribution, and swirl effect of first air flow, and ash elimination.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1499-1504
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• 2004

Flue gas recirculation (FGR) is a method used to control oxides of nitrogen ($NO_x$) in combustion system. The recirculated flue gases resulted in slow reaction and low flame temperatures, which in turn resulted in decreased thermal NO production. Recently, it has been demonstrated that introducing the recirculated flue gas in the fuel stream, that is, the fuel induced recirculation (FIR), resulted in a much greater reduction in $NO_x$ per unit mass of recirculated gas, as compared to introducing the flue gases in air. In the present study, the effect on $NO_x$ reduction in turbulent swirl flame in laboratory scale using FGR/FIR methods through the dilution using $N_2$ and $CO_2$. Results. show the $CO_2$ dilution is more effective $NO_x$ reduction methods because of large temperature drop due to the larger specific heat $CO_2$ compared to $N_2$. FIR is more effective to reduce $NO_x$ emission than FGR when the same recirculation ratio of dilution gas.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.2 s.233
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• pp.180-188
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• 2005

It is well known that a lean burn engine caused by stratified mixture formation has many kinds of advantages to combustion characteristics, such as higher thermal efficiency and lower CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can achieve low fuel consumption technology, it produces much unburned hydrocarbon and soot because of heterogeneous equivalence ratio in the combustion chamber. Therefore, the stratified mixture formation technology is very important to obtain the stable lean combustion. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The local effect of mixture formation according to control air-fuel distribution in the chamber was examined experimentally. In addition, the effect of turbulence on stratified charge combustion process was observed by schlieren photography. From this study, we found that the flame propagation speed increase with swirl flow and the swirl promotes the formation of fuel and air mixture.

• Clean Technology
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• v.26 no.3
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• pp.211-220
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• 2020

This experimental study investigates the design parameters to achieve ultra low NOx combustion of coal using a 80 kW capacity single-burner furnace. The influence of key design parameters such as SN, overall and burner-zone equivalence ratios, primary/secondary air ratio, overfire air (OFA) ratio were tested for a total of 81 cases. The results showed that weak swirl intensity of the burner leads to higher NOx emission whereas strong swirl intensity accompanies increased CO concentration desipte lower NOx emission. Therefore, finding an appropirate swirl intensity is essential for the burner design. Larger flow rate of secondary air increased NOx emission, whereas smaller flow rate stretches the flame and increased CO emission. The lowest NOx emission of 82 ppm (6% O₂) was achieved at the optimal condition of the present burner deisgn. It is expected to furrther lower the NOx emission by introducing splitting the burner secondary air into three or four streams.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.698-703
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• 2000

The characteristics of NOx emission in reburning process have been experimentally studied. The design point of burner is creative of three distinct reaction zones; a primary flame zone that NOx producted, reburn zone to reduce the primary zone NOx and burnout zone. Liquefied Petroleum Gas(LPG) was used as main and reburn fuels. Process parameters investigated included main/reburn fuel ratio, primary/secondary air ratio, reborn fuel injector position and different designed quarl. The NOx emission characteristic of aerodynamic designed burner relied on reborn fuel ratio and was slightly affected by a reburn fuel injector position and quarl shape.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.379-384
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• 2003

Coal-burning utilities are facing a major NOx control compliance challenge due to the heavy emission regulation. In response to this challenge, some applicative technologies to effectively reduce NOx are developed and applied in the pulverized coal power plants. One of these is low NOx burner(LNB) equipped with multi-staged air register. In this study, NOx emission rate and flame shapes are investigated with secondary and tertiary air flow conditions in air staged coal burner, and the optimal windows of flow conditions to minimize NOx emission rate are found out. The test conditions treated in this study are the flow rate, swirl direction and intensity and throat injection velocity of secondary and tertiary air.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.764-769
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• 2001

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 pollutant emission. One of these studies is how to control the profile of particle injection and velocity dependant on coal nozzle. Basically, a mixed flow of gas and particle in coal nozzle is required to have appropriate injection and concentration distribution at exit to achieve flame stability and low pollutant, but it is very difficult to obtain that without help of a coal separating device within nozzle. In this study, each distribution of air and coal flow rate is measured for the coal nozzle with coal separator developed by us. The coal concentration at exit is various according to inlet swirl values and positions of coal separator. Also pressure drop is measured for various operating conditions of this nozzle. From these results, we can find the separation characteristic of new developed coal separator, and select proper operation range of coal nozzle. When this coal nozzle is applied to actual plant, these investigations will be very useful to confirm the shape of coal separator to have efficient particle injection.

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.279-282
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• 2002

Recently, gas turbines for power generation adopt multistage DLN(Dry Low NOx) type combustion, where diffusion combustion is applied at low load and, with increase in load, the combustion mode is changed to lean premixed combustion to reduce NOx emissive concentration. However, during the mode changeover from diffusion to premixed flame, unfavorable phenomena, such as flashback, high amplitude combustion oscillations, or thermal damage of combustor parts could frequently occur. In the present study, to apply for the analysis of such unfavorable phenomena, three-dimensional CFD investigations are carried out to compare the detailed flow characteristics and temperature distribution inside the gas turbine combustor before and after combustion mode changeover. The fuel considered here is pure methane gas. A standard $k-{\varepsilon}$ turbulence model with wall function and a P-N type radiation heat transfer model, have been utilized. To analyze the complex geometric effects of combustor parts on combustion characteristics, fuel nozzles, a swirl vane f3r fuel-air mixing, and cooling air holes on the combustor liner wall, are included in this simulation.