SIMULATION OF ASH DEPOSIT GROWTH IN A PULVERIZED COAL-FIRED PILOT-SCALE REACTOR

A model has been developed to relate the deposition behavior of ash un der slagging conditions to boiler operating conditions and coal compos ition data. This model has been incorporated into a comprehensive comb ustion code and used to investigate the effects of ash deposition rate , thermal conditions, and ash chemistry on slag growth in a pilot-scal e combustor. Results for simulated deposits from a coal blend fired at 3.7 MBtu/h showed a relatively high liquid fraction corresponding to denser and presumably stronger deposits. The same coal blend fired at a lower rate produced deposits which were less dense because of the lo wer temperatures and heat flux levels in the combustor, as well as the lower ash deposition rates. Deposition from a cleaned version of the same blend was also simulated at 3.7 MBtu/h and showed less potential for liquid-phase formation than the uncleaned blend. These results are in qualitative agreement with experimental results and illustrate the importance of operating conditions on deposit formation.