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Show Paper No. 23 INFLUENCE OF OPERATING CONDITIONS AND COAL CHARACTERISTICS ON ASH DEPOSITION IN A PILOT-SCALE COMBUSTOR ABSTRACT M. C. Ma i Consolidation Coal Company Research and Development 4000 Brownsville Road Library, PA 15129 Ani nit i a 1 stu d y has bee n com p 1 e ted des c rib i n gas h de p 0 sit ion r e 1 ate d phenomena in a pilot-scale (1.5 MM Btu/hr) combustor. Statistical analyses were performed on slagging and fouling data from over 130 combustion tests using 33 different fuels. Slagging-induced heat flux reductions to a simulated water-wall were found to be highly dependent on operating conditions and firing mode (wall, opposed-wall, tangential) and less significantly related to coal characteristics. Fouling problems (in the form of tenacious deposits and/or convection section pressure drop difficulties) were found to be related to exit gas temperature, as-fired ASTM fusion temperature, ash loading, and fly ash mass-median particle size. Bulk deposit elemental ash oxide composition was found to be related to location, operating conditions and coal characteristics. The results, although somewhat intuitive, suggest that substantial improvements in the predictive accuracy of slagging and fouling correlations may be possible. In empirical terms this will require the inclusion of additional coal chemical/physical characteristic parameters and a continued evaluation of the importance of operating condition effects (temperatures, flow patterns, particle size distributions, etc.) on ash deposition related phenomena. INTRODUCTION Deposition of ash on heat transfer surfaces of coal-fired boilers can drastically affect the economics of power generation as manifested in evaluations of plant performance and rel iabil ity. A strong impetus currently exists for improving the ability to predict new fuel performance in light of the economic consequences of switching, blending and /0 r c 1 e ani n g co a 1 s . T his pap era t t em p t s to add res son e asp e c t 0 f this realization - the link between operating conditions and coal physical/chemical characteristics and several ash deposition related phenomena. The problems with traditional slagging and fouling correlations are really two-fold. First, the inherent complexity of the deposition process must be recognized along with the realization that methods used to predict this phenomenon might, by nature be similarly complicated. This is why existing one, two, or even three parameter correlations only yield 50-70% success rates.{l) Second, existing slagging data are either proprietary and unavailable, to a large extent incomplete or |