In-stack particle size and composition transformations during circulating fluidized bed combustion of willow and forest residue

The in-stack transformations of the particle size and composition of the fl y ash were studied experimentally during combustion of forest residue and w illow in a 35 MW circulating fluidized bed co-generation plant. Samples of the in-stack fly ash were taken with 11-stage Berner low pressure impactors (BLPIs) at two locations in the flue gas stream, i.e., downstream of the c irculating cyclone at a temperature of 810-850 degrees C and downstream of the convective back pass at a temperature of 150-160 degrees C. The mass si ze distribution of the fly ash was derived from weighing the BLPI substrate films. For obtaining the multielemental composition of the fly ash as a fu nction of particle size, the BLPI films were analyzed by both particle-indu ced X-ray emission (PIXE) and instrumental neutron activation analysis (INA A). (C) 1999 Elsevier Science B.V. All rights reserved.