The Conditions for Boiler Bank Plugging by Submicrometer Sodium Salt (Fume) Particles in Kraft Recovery Boilers

A method for predicting the conditions that lead to plugging of the boiler bank by submicrometer condensation aerosols of alkali-metal salts in kraft recovery boilers has been developed and evaluated against field observations. The method is based on recent data on the phase behavior and sintering characteristics of compacts of dusts from kraft recovery boilers, both of which are dependent on the inorganic composition of the particles. The method also takes into account the thermal load on the boiler and the specific design characteristic of the gas temperature entering the boiler bank versus thermal load on the boiler. The prediction method presented in this paper has been tested against data from 20 different recovery boilers. It correctly predicted whether the boiler did or did not encounter problematic fume deposits for 80% of those boilers.