Investigation of thermal radiation of furnace gases generated from solid-fuel combustion in a steam boiler

Abstract

The article presents a methodology of comprehensive study of thermal radiation emitted by furnace gases during solid fuel combustion. The characteristics of initial fuel and chemical composition of flyash are described. The absorption coefficients of the gaseous phase in relation to the wavelength, temperature, and concentration of the main gas components are measured. The gas composition was determined by calculation of the total combustion products, as well as experimentally (through a gas analyzer). The experimental results on the particle shapes and sizes, the distribution function of flyash particles, the fusibility of mineral part were used to calculate the radiation characteristics of the condensed phase. Calculations of emission characteristics of furnace gases (spectral and integral flux densities and emissivity factors) depending on the influence of each phase at different operating temperatures are presented. The method efficiency is estimated through comparing with calculated and experimental data on the emission characteristics for homogeneous and heterogeneous combustion products. Spectral ranges were chosen to determine the temperature for furnace gases, a plume, and the surface of flyash deposits on the furnace walls. Experimental dependences of the emissivity factors for flyash deposits on temperature are presented. The findings can be used to calculate heat fluxes, for the purposes of furnace gases pyrometry, and to determine the temperature level in the compilation of operational maps for the boiler.