ABSTRACT
Sodium and potassium behaviour in a power plant scale atmospheric circulating fluidised bed combustion (CFBC) of bituminous coal was studied in an 80 MW(th) boiler. In the experimental part of the work we determined the particle size distributions in the size range 0.01-70 pm for mass and several elements by collecting aerosols with a low-pressure impactor-cyclone sampling train, and analysing the samples gravimetrically and with INAA, PIXE and IC. The number size distributions of the aerosols were determined with a differential electrical mobility method in the size range 0.01-0.8 pm. A numerical aerosol simulation model was used to study the alkali behaviour after the CFBC process cyclone. Less than one percent of total alkalis in coal were found as water soluble after combustion. The modelling results support the experimental result that no more than one percent of alkalis have been condensed from the gas phase. The major part of the alkalis was found in aluminosilicates.
