Reaction Enhanced Vaporization of Molten Salt

Vaporization of molten salts results in serious problems in the operation of many combustion systems. Salt vaporization of special importance in the burning of kraft black liquor, where combustion occurs in a molten Na2S/Na2CO3 environment. In this paper, it is shown that the vaporization of alkali carbonate during air oxidation of Na2S/Na2CO3 results from Na oxidation in the gas phase. Oxidation of Na in the gas phase significantly lowers the partial pressure of Na. Since the driving force for vaporization is the difference between the equilibrium vapor pressure of Na at the gas-melt interface and the partial pressure of Na in the gas phase, this reduction in partial pressure of Na significantly increases Na vaporization rates and allows fuming to proceed with only mild reducing conditions in the melt.