Plantwide dynamics and control of processes with crystallization

Recently Ward et al. [Ward, J. D., Doherty, M. F., & Yu, C. C. (2007). Plantwide operation and control of processes with crystallization. AIChE Journal, 53, 2885–2896] presented new shortcut expressions for the steady-state operation of plantwide processes with crystallization. The method allows the engineer to predict the steady-state gain between the production rate and certain other key process variables for various choices of controlled variables. The result is a simple analytical model that shows how the process operates for various choices of control structure. The previous work of Ward et al. considered only steady-state process operation. In this contribution we apply the method and results from our previous work to develop plantwide control structures, and test the structures using a rigorous non-linear dynamic process model. We demonstrate that the method produces workable plantwide control structures, and that the steady-state behavior of the dynamic process is consistent with the predictions of our previous work.