A PARAMETRIC EVALUATION OF PARTICLE-PHASE DYNAMICS IN AN INDUSTRIAL PULVERIZED-COAL-FIRED BOILER

A parametric study on the variation of particle size, velocity and num ber density with boiler operating conditions has been completed in a f ull-scale, tangentially fired, 85 MW(e) pulverized-coal-fired boiler, using a laser-based diagnostic probe. Variables in the lest included b oiler load (60 or 85 MW,), coal type and excess air (2.5 or 4.5%). Two bituminous coals were used: HV and LV, with 7 and 10wt% ash respectiv ely. Measurements were made in the radiant section, at the entrance to both the convective pass and economizer, and downstream of the econom izer. Variations in particle velocity profiles were correlated with ch anges in boiler load. Port-to-port velocity variations were associated with changes in the gas flow field imposed by boiler geometry and wit h gas temperature reductions at downstream locations. Differences in t he particle size distribution for a single coal type were nearly alway s associated with changes in the number density of particles > 10 mu m . Mass loading profiles varied with location in the boiler and coal ty pe. In the radiant section of the boiler, these profiles support a cen trifugal effect exerted on the condensed phase by the rotating flow. T hroughout the boiler, mass loadings for the LV coal tests were consist ently higher than those for the HV coal.