화학공학소재연구정보센터
KAGAKU KOGAKU RONBUNSHU, Vol.34, No.3, 344-350, 2008
Development of Radiative Heat Transfer Model for Pulverized Coal Combustion
A radiative heat transfer model for pulverized coal combustion was developed. The monochromatic extinction of pulverized coal particles dispersed in liquid paraffin wax was measured spectroscopically by using FT-IR. The effects of absorption and scattering could be expressed by the extinction efficiency, which was calculated from electromagnetic theory. The extinction efficiency was applied to the developed radiative heat transfer model. To evaluate the accuracy of the developed radiative transfer model, radiative heat transfer and combustion analyses of a turbulent Pulverized coal-fired furnace (coal feed 6 kg (.) hr(-1)) were carried out. Calculations were performed for three cases: without radiative heat transfer, with the radiative heat transfer model in which the particle emissivity is assumed to be a function of unburned carbon, and with the developed radiative heat transfer model. The influence of radiative heat transfer appeared particularly as differences in the ignition position and the relaxation of the temperature gradient around the flame zone, because the preheating effect of coal particles near the burner nozzle is enhanced by the absorption of radiation energy propagated from the combustion area. The calculated temperatures agreed with measurements when the developed radiative heat transfer model was applied. This proves the accuracy of the developed radiative heat transfer model in which the extinction coefficient is used to express the radiative properties of pulverized coal clouds.