Flat-flame burner studies of pulverized-coal combustion

摘要

The propagation of laminar, premixed pulverized-coal flames has been studied experimentally. A flat-flame coal-dust burner was used to obtain multiphase temperature and composition profiles for validating a one-dimensional coal combustion model. The burner and associated diagnostics were modified in this work to enhance the accuracy and spatial resolution of the data. The infrared pyrometer was improved by addition of two more detection wavelengths and traversing optics that enable both radial and axial temperature measurements. Six different coals from the United States, South Africa, Colombia, and Australia were burned. Measurements included gas- and particle-phase line-of-sight temperatures, major gas species concentrations, and solids sample composition at different axial locations within the flame. Temperature measurements of methane flames, as well as carbon-, coal-, and SiC-seeded methane flames were obtained. Radial line-of-sight measurements of each flame were taken and used along with tomographic methods to reconstruct local temperature profiles. An accurate technique called absorption/emission tomography shows local temperatures to be close to the line-of-sight temperatures for the optically-thin flames. Scatter in carbon/coal flame data is attributed to uncertainties in the absorption coefficients and interference from soot emission. The flame speed results indicate a weak dependency on heating value, but transport processes are likely a key influence on flame propagation. The results can be used as a basis for interpreting thermochemical processes occurring in pulverized-coal combustion. (EG) 28 refs.