A transient numerical algorithm to predict temperature and liquid content of carryover in kraft recovery boilers

grantor: University of TorontoDeposition of carryover, the molten or partially molten smelt particles, in kraft recovery boilers is primarily a function of velocity, temperature, and liquid content of the carryover upon impact on heat transfer surfaces. In this study, an algorithm to track the velocity, temperature, and liquid content of carryover was developed and integrated within a commercially available computational fluid dynamics (CFD) package. The algorithm was used to track Na2SO4-NaCl-K2SO4 containing particles numerically seeded within CFD simulations of the gas flow through an EFR and a simplified model of the upper furnace of a kraft recovery boiler. The predicted particle velocity, temperature, and liquid content results agreed well with the EFR impact and deposition experimental data. The upper furnace particle temperature and liquid content results predict, under the simplified conditions considered, that deposits will form primary on the first and second platens of a clean boiler while in a fouled boiler deposits stop growing on the first platen but continue to grow on the second platen. In both boiler cases, smaller particles deposit uniformly across the height of the tubes in superheater section while larger particles preferentially deposit on the upper part of the tubes and the top wall. These results are in agreement with literature and other numerical studies.M.A.Sc