PYROLYSIS OF COAL MACERAL CONCENTRATES UNDER PF-COMBUSTION CONDITIONS(II) - CHANGES IN HETEROATOM PARTITIONING AS A FUNCTION OF RANK

Differences between maceral types with respect to heteroatom partition ing during pyrolysis under conditions representative of pf-combustion have been investigated. Pyrolysis experiments have been carried out in a wire-mesh reactor; maceral concentrates and whole coals have been h eated at 5000 degrees C s(-1) to 1500 degrees C, in atmospheric pressu re He. The proportion of N-retention in chars was found to increase fr om about 10 to 60% in the 75-95% elemental-Ci range, irrespective of m aceral composition. However, char-N retention by inertinites was sligh tly less than that for vitrinites; retention by liptinites was clearly less than that for vitrinites. The general trend for sulfur retention was similar: for vitrinite and inertinite concentrates, sulfur retent ion increased from about 30 to 60% over the 72-95% elemental-C content interval. Once again, retention in liptinites was considerably lower- between 5 and l5%-for the three samples used in the study. Ash content s of the present set of samples suggest that it would not be realistic to discuss the present set of sulfur retention data in terms of organ ic sulfur alone. The work outlined above lead to several tentative con clusions, pinpointing areas where new structural work is required. (C) 1998 Elsevier Science Ltd. All rights reserved.