Characteristics of Flue Gases and Ash in Oxygen-Blown Pulverized Coal Combustion

概要

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A new coal combustion technology for a large-scale power plant is required to be applicable to various kinds of coal. An oxygen-blown pulverized coal combustion experiment was investigated with a bench scale apparatus to understand such characteristics as the combustion efficiency, NOx concentration, conversion from fuel-N, the unburned fraction and composition of mineral matter in the collected ash. The experiment was conducted in a down-fired, cylindrical and vertical furnace. The primary oxygen is injected into the ejector to carry coal particles to the burner, and the swirled secondary one is fed through an annulus. The CO2 concentration in flue gas was much higher than that of air–coal combustion, and the value was eight out of ten. The results made a feasible condition for CO2 separation and sequestration. The NOx emission was ranged in concentrations from 1650 to 1800 ppm in the complete combustion region. The NOx concentration was much higher, however the NOx conversion ratio was about the same level as the case of air combustion. The decrease of low-boiling component such as Na, Mg, K and Ca was identified because the flame temperature of the oxygen-blown coal combustion was achieved about 3000 K. We suggested the vaporized calcium components in the fly ash have a potential of the furnace desulfurization and the effect of SOx attack to the heat exchanger was inhibited.
2007-07-01