Industrial & Engineering Chemistry Research, Vol.43, No.25, 8117-8132, 2004
Distributed parameter model of black liquor falling-film evaporators. 2. Modeling of a multiple-effect evaporator plant
In the first of two parts of this work, a distributed parameter model, based on first-principles knowledge about the fluid dynamics and heat-transfer processes, was developed for the evaporation side of a single plate (lamella) of a falling-film evaporator. In the second part, the work expands on the single-plate model to develop a fundamental model of a falling-film evaporator that accounts for the condensation side of the plate, the heating/flashing section at the evaporator entrance, the evaporator inventory, mixing, and recirculation flows. On the basis of the single evaporator model, a multiple evaporator plant that consists of one superconcentrator (three falling-film evaporators as one unit) and four falling-film evaporators is modeled. The model, its numerical solution, and its behavior at different operating conditions are presented and discussed.