TUTCRIS - Tampereen teknillinen yliopisto


Modeling fine particles and alkali metal compound behavior in a kraft recovery boiler



JulkaisuTAPPI Journal
TilaJulkaistu - 2012
OKM-julkaisutyyppiA1 Alkuperäisartikkeli


Under certain conditions, ash in black liquor may form a locally corrosive environment in a kraft recovery boiler. The ash may also cause efficiency losses and even boiler shutdown due to plugging of the flue gas passages. The most difficult compounds in a fuel such as black liquor are potassium (K) and chlorine (Cl), because they change the melting behavior of the ash. Fouling and corrosion of the kraft recovery boiler are widely researched, but there have not been many computational models on the subject. This article presents a computational fluid dynamics (CFD) based modeling method for the reactions between alkali metal compounds and for the formation of fine fume particles in a kraft recovery boiler furnace.

The modeling method discussed here is based on the ANSYS/FLUENT software and its Fine Particle Model (FPM) extension. The modeling method enables the examination of gaseous alkali metal compound and fine fume particle distributions in a kraft recovery boiler furnace. For example, the effect of temperature and the boiler design on these variables can be predicted with the model. In addition to the model itself, some preliminary results obtained with it are presented at the end of this article. When the model is developed further, it can be extended to the superheater area of the kraft recovery boiler. This will give new insight into the variables that increase or decrease fouling and corrosion there.


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