Ignition, explosion, and flame propagation characteristics of a low-rank coal

A low rank coal was carefully collected and prepared and its explosion and oxidation characteristics examined. The study Decker subbituminous coal was shown in explosion bomb tests to be much more easily ignited than a reference Pittsburgh bituminous coal dust, and with an explosive potential at least equal to that of the reference coal. Particle size and moisture content were shown to strongly influence the minimum ignition energies and minimum autoignition temperatures of the study coal. A limit to the effect of particle size on explosive pressure rise rate was suggested.;A flat-flame, steady flow reactor was designed, built, calibrated, and operated. Reactor performance was calibrated with natural gas and some observations of natural gas flames were made. Steady coal dust flame tests demonstrated a large dependence of measured flame speed on the separation distance from the flame holder, uniformity of coal dust distribution across the flame holder, and coal dust concentration. Reactor preheating, flame length, coal type, particle size, and moisture had lesser impacts on measured flame speeds, within the uncertainty of the data. However, observable burning characteristics such as soot formation, gas temperature, and flame length did vary widely when these factors were changed.