Rates and equilibria of devolatilization and trace element evolution in coal pyrolysis. Final report Sep 79-Jun 81

The report gives results of using a laminar-flow furnace to study the kinetics of devolatilization and evolution of S, As, Pb, and Hg in the pyrolysis of pulverized coal in nitrogen. Variables included pyrolysis time, reactor temperature, and coal type. Devolatilization rates and weight losses of the two subbituminous coals tested were lower than those of a bituminous coal. The four elements were released in significant quantities during rapid pyrolysis, with the elemental loss from the bituminous coal proceeding more rapidly and to a greater extent than that from the subbituminous coals. Emissions of As and Pb in subbituminous coal and Pb in bituminous coal were found to be proportional to the total volatile matter released. Emissions of Hg and As in bituminous coal were proportionately greater than the total volatile matter released. The S released was proportional to the amount of dry-ash-free volatile matter released for both coals. Five kinetic models for devolatilization were tested.