EFFECTS OF SULPHIDE ON MELTING TEMPERATURES OF SMELT AND CARRYOVER IN KRAFT RECOVERY BOILERS

摘要

The effects of sulphide on the melting temperatures of alkali salt mixtures containing sodium (Na), potassium (K), carbonate (CO_3), sulphate (SO_4), sulphide (S), and chloride (Cl) are systemically studied using a Differential Scanning Calorimeter and an advanced multi-component thermodynamic program, FactSage. The results show that sulphide has a relatively small effect on the first melting temperature (FMT), the complete melting (CMT) of carryover deposits and smelt compared to chloride and potassium, but has a significant effect on the sticky temperature of carryover, particularly when the Cl content is low. While the freezing temperature of smelt depends greatly on sulphidity, at a given sulphidity, it is not appreciably affected by reduction efficiency. The results provide a better understanding of the effects of sulphide on smelt fluidity in the lower furnace and on fouling and corrosion caused by carryover in the superheater region of recovery boilers.