In cases where limestone is added to reduce SO2
concentration in the flue gas, as in most of the experiments
of this study, the molar ratio of S in flue gas-to-Cl in fuel
molar ratio (Sfg/Cl) is better Cl deposition indicator than S/Cl
molar ratio in the fuel. Table 5 shows the two molar ratios for
the combusted blends in 100 kW CFB reactor. Theoretically, a
Sfg/Cl molar ratio of at least 0.5 would be required to sulfate
all the alkali chlorides released to the gas phase during
combustion. This is interesting to note that chlorine deposition
during combustion of 60SAC40RDF was negligible even
though Cl concentration in the fuel was significant (0.25%)
and Sfg/Cl molar ratio was 0.4, i.e., below the theoretical limit of 0.5. We suggest that it is due to the capture of alkali
chlorides by the available aluminosilicates (namely kaolinite)
contained in coal-ash (Table 6).