On the basis of the minimum Gibbs free energy principle

this paper investigates the influence of sodium in coal on the formation of SO_3 during conventional air combustion by using the reaction kinetics method. The relationship between the formation and transformation of gaseous sodium compounds and the formation and consumption of SO_3 were analyzed. The results indicate that

in the conventional combustion mode

when the flue gas does not contain Na Cl

the amount of SO_3 vapor produced is the most along the flue gas flow. When the flue gas contains Na Cl

the higher the initial volume fraction of Na Cl vapor

the smaller the amount of SO_3 vapor produced along the flue gas flow. When the flue gas temperature is high

the formation and conversion of gaseous sodium phase has no effect on the volume fraction of SO_3. When the flue gas temperature is low

the formation of Na HSO4 in gas phase consumes SO_3

which reduces the volume fraction to zero. The formation of gaseous Na2 SO4 has no effect on the volume fraction of SO_3 and is mainly controlled by the gas phase formation of sulfite precursors. The distribution of H

O

and OH free radicals in the flue gas is not affected by sodium. Therefore

in the conventional combustion mode

sodium has an inhibitory effect on the formation of SO_3.