Black Liquor Falling Film Evaporation: Computational Model and Pilot Experiments

Paper in proceeding, 2014

The focus of this work is to improve our understanding of the black liquor evaporator fouling process. The investigation method is two pronged, consisting of the development of a computational model paired with experiments conducted in a pilot evaporator. Experiments for black liquor at solids up to 45% dry solids were conducted and used to validate the computational model. It was found that for fixed Reynolds number, lowering pump frequency induces waves closer to the inlet. And, for fixed pumping frequency, increasing the Reynolds number has the effect of inducing waves closer to the inlet. The numerical model reproduces the complex waves structures present in black liquor flow. The model and pilot plant are to be used to investigate the effect of relevant parameters for the hydrodynamics, heat transfer, and soluble scale fouling of black liquor, which is of specific concern to the pulping industry.