Distillation Column Control
Steady-state simulation and design methods for separation processes, with emphasis on distillation, have been presented in detail in many references, a few of which are listed in the references for this chapter. This chapter will present a discussion of the basic control schemes for distillation columns. Let us start by stating the obvious: the amount of literature on separation processes, particularly distillation is colossal. Particularly readable books and references are those by Buckley [1,2], King , Tyreus , Seborg et al. , Shinskey , Smith and Corripio , Svrcek and Morris  and Wilson and Svrcek .
8.1 Basic Terms
When determining the control system design for a multivariable process, the terms control strategy, control structure and controller structure are used interchangeably. In this context, the meaning is the selection and pairing of manipulated and controlled variables to form a complete, functional control system. However, the three terms can also have individual meanings. Control strategy can describe how the control loops in a process are configured to meet a given overall objective such as the purity of a given stream. Control structure, on the other hand, is the selection of controlled and manipulated variables from a set of many choices. Finally, controller structure means the specific pairing of controlled and manipulated variables by way of feedback controllers.
This chapter will describe a methodology for designing ...