Coal Pyrolysis in Flat, Laminar, Opposed Jet Combustion Configurations

摘要

A laminar, counterflow, premixed flame configuration was utilized to investigate coal pyrolysis under both reducing and oxidizing environments, and at superficial heating rates between 20,000 and 70,000 K/s. Whether the unique attributes of this system can be exploited to yield quantitatively interpretable data, depends first on the adequacy of mathematical models of the entire heterogeneous flow system, and second, on the experimental realization of a sufficiently close approximation to the theoretical model. The purpose of this research was to determine if both these criteria could be met and to demonstrate the utility of the laminar opposed flow configuration as a tool for quantitative coal pyrolysis studies. Theory demonstrated that this configuration is one dimensional in temperature and species concentrations, and that particle trajectories and particle time temperature histories can be determined precisely, even though particles do not follow gas streamlines. Particle trajectories may be over damped or oscillatory, but time temperature histories of particles sampled are dependent only on axial, not radial, sampling position. Experimental data for coal pyrolysis in flue gases from rich CH sub 4 /O sub 2 /N sub 2 flames validated the one dimensional aspects of the theory and yielded information on particle morphology during pyrolysis. Additional data from an H sub 2 /O sub 2 /N sub 2 flame yielded CO, CO sub 2 , and light hydrocarbon species profiles and species devolatilization rates for two different coals, each under slightly reducing and slightly oxidizing conditions. Differences between coals exceeded those between oxidative and reducing conditions for the same coal. 7 refs., 7 figs., 1 tab. (ERA citation 12:028259)