Ignition and devolatilization of pulverized bituminous coal particles during oxygen/carbon dioxide coal combustion

摘要

Oxygen/carbon dioxide recycle coal combustion is actively being investigated because of its potential to facilitate CO_2 sequestration and to achieve emission reductions. In the work reported here, the effect of enhanced oxygen levels and CO_2 bath gas is independently analyzed for their influence on single-particle pulverized coal ignition of a U.S. eastern bituminous coal. The experiments show that the presence of CO_2 and a lower O_2 concentration increase the ignition delay time but have no measurable effect on the time required to complete volatile combustion, once initiated. For the ignition process observed in the experiments, the CO_2 results are explained by its higher molar specific heat and the O_2 results are explained by the effect of O_2 concentration on the local mixture reactivity. Particle ignition and devolatilization properties in a mixture of 30% O_2 in CO_2 are very similar to those in air.