FIELD STUDIES ON FUME CHEMISTRY AND DEPOSITION IN KRAFT RECOVERY BOILERS

The chemistry and rte of accumulation of fume deposits at various loca tions in two recovery boilers at different mills were investigated usi ng a fume deposition probe. Similar results were obtained at both boil ers. In the lower furnace, fume deposits contained as much as 26 wt% a lkali hydroxides (NaOH+KOH). In the upper furnace, no hydroxide was fo und; the chloride and potassium contents were relatively constant, whe reas the carbonate content increased progressively towards the back en d of the boiler. The study also indicates that the majority of solid f ume starts forming at a location near the entrance of the generating b ank, where the flue-gas temperatures is about 60 degrees C.