Dynamic simulation of multi-effect evaporators

Multi-effect evaporators are widely used for concentrating solutions in a variety of important industrial applications ranging from desalinization to biorefining. The use of multi-effects achieves very significant process intensification since energy consumption is reduced in direct ratio to the number of effects. Steady-state design has been discussed in many papers and books. Far fewer studies of their dynamic simulation and control have appeared in the open literature. This paper reviews some of the design issues and demonstrates how a dynamic simulation can be developed using standard Aspen simulation models. The dynamic model must be set up such that the vapor from each evaporator is completely condensed in the downstream lower-temperature evaporator while satisfying heat-transfer constraints.