Structure and thermochemical kinetic studies of coal pyrolysis. Final technical report

摘要

The structure and kinetics of low rank coals, namely, Montana Rosebud subbituminous and Beulah lignite coals have been studied. C0(sub 2) laser heating of separated arrays of particles at high flux levels has made possible the investigation of the pyrolysis and char oxidation processes of lignite and subbituminous coal particles as a function of exposure time at laser fluxes of 200--300 w/cm(sup 2). The Beulah lignite and Rosebud subbituminous coals studied were supplied by the Penn State Coal Sample Bank. They had been collected, ground, and packaged in an inert atmosphere. The coal samples were subsequently stored, sieved, carefully dried, and maintained in a glove box under dry nitrogen. The moisture loss of the as-received samples was within experimental error of the supplied ASTM analysis. The mass loss vs time reported here are for particles that were dried at 120(degree)C under nitrogen. The morphological changes in the particles with laser exposure was monitored by scanning electron microscopy. Correlation of weight loss data with microscopic observation has been made for the devolatilization in air atmosphere. Care was taken to insure that mass loss did not reflect loss of particles. Pyrolysis rates were determined for particles in air and in a nitrogen flow, and compared with the results of corresponding laser pyrolysis studies of high and low-volatile bituminous coal particle arrays. Elemental analysis of the char particles were also carried out. The studies were extended to a typical run-of-the mill coal samples collected from a power generating company.