Distillation control using passivity

Publisher Summary This chapter presents the design of an asymptotically stable control system for homogeneous multicomponent distillation. The control system is designed using passivity and thermodynamic based analysis. One design solution is presented to illustrate the use of passivity and thermodynamics to better understand the distillation control problem. The configuration presented is based on the fundamentals of thermodynamics where pressures are used for mass balance control, temperatures for energy balance control, and chemical potential are related to composition control. The chemical potential and its relation to composition are explored to show complications that can occur in azeotropic distillation. The temperature and temperature difference can be updated in the controllers from either concentration measurements, where possible, or from a model of vapor–liquid equilibrium (VLE) data.