• 한국연소학회지
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• 제11권2호
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• pp.1-6
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• 2006

This report presents a study of the development of an advanced coal nozzle used in burners to reduce unburned carbon (UBC) in a tangential coal-fired boiler. To understand the mechanism of UBC reduction, experiments using conventional burners were carried out to evaluate the effects of air injection velocity, coal fineness and over fired air (OFA) on combustion efficiency. It was confirmed that ignition of pulverized coal particles close to the burner is helpful toward the complete burn of residual carbon in fly ash. These efforts indicated the additional results that UBC was strongly dependent on the primary air velocity and coal fineness; especially that UBC dramatically decreased when the weight fraction of pulverized coal under $75{\mu}m$ was over 85 %. New coal nozzles, modified from conventional nozzles, were prepared and tested to improve the combustion efficiency. Some of these nozzles offered relatively lower unburned carbon than those of conventional burners and are referred to as HPFS (High Performance Flame Stability) coal nozzles.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.967-972
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• 2001

The emission of $NO_{x}$ during coal combustion is a major reason of environment impact. $NO_{x}$ is an acid rain precursor and participates in the generation of smog through ozone production. $NO_{x}$ can be divided into thermal $NO_{x}$, fuel $NO_{x}$ and prompt $NO_{x}$. Thermal $NO_{x}$ is formed in a highly temperature condition dependent. Fuel $NO_{x}$ is dependent on the local combustion characteristics and initial concentration of nitrogen bound compound, while prompt $NO_{x}$ is formed in a significant quantity in some combustion environments, such as low temperature and short residence times. This paper presents numerical simulation of the flow and combustion characteristics in the furnace of a tangential firing boiler of 500MW with burners installed at the every comer of the furnace. The purpose of this paper is to investigate the reduction of $NO_{x}$ emission in a 500MW pulverized coal tangential firing boiler with different OFA's and burner angles. Calculations with different air flow rates of over fired air(OFA) and burner angles are performed.