Volatiles Mass Transport within Particles of Softened Coal. Technical Progress Report, April 1-October 20, 1986

摘要

A mathematical model is developed to describe the intraparticle effects of unsteady volatiles transport, chemical kinetics of metaplast formation and depletion, and transient plastic behavior in softening coal pyrolysis. In the pyrolysis process, coal is converted into metaplast and gases via chemical-bond breaking and physical melting. The viscous, fluid-like metaplast further decomposes to form gases, tar, and coke. The transports of gaseous species to the particle surface and to the bubbles which are originated from the sealed pores in the metaplast phase are related to the plastic behavior of coal. The bubbles may grow due to the influx of gaseous volatiles adn the decomposition of tar evaporated from the metaplast. Through the break-up of bubbles on the particle surface, the tar and the light gases in bubbles are released into the ambient. The main objectives of this model are to quantitatively simulate the coupled effects of transport and kinetics and to predict the independent effects of reaction temperature, pressure, particle size, and heating rate on the volatiles yields and the extent of swelling during pyrolysis. (ERA citation 12:000012)