INVESTIGATION OF ASH DEPOSITION AND AIR TOXICS PATHWAYS IN BOILER DOWNSTREAM OPERATIONS

摘要

Aspects of ash deposition and trace specie enrichment encountered in a boiler freeboard and downstream are identified and investigated; next, solution approaches are developed for four example cases based on field data, with directions provided for subsequent refinement of the analysis. In particular, problems relating to condensation/nucleation, phoretic phenomena, and coagulation of both refractory mineral and trace mineral species contained in the entering ash are examined, using a previously developed code AEROSOL. The analysis thus tracks the fate of air toxics in the entrained, deposited, and emitted flyash. Such an analysis should ultimately facilitate the improved design of the combustor freeboard, thermal recovery equipment, and emission control equipment, for the minimization of air toxics release.