Plant design based on economic and static controllability criteria

A methodology is developed that screens process designs and control system configurations, defined in terms of selected controlled and manipulated variables, that exhibit poor steady-state behavior under the presence of multiple simultaneous disturbances. The steady-state disturbance rejection characteristics of the nonlinear process models are considered in conjunction with economic criteria for the plant design. The steady-state control objectives for the system are incorporated within an optimization framework. Sensitivity information of the optimal solution is utilized to modify the design parameters for improved static controllability performance. The design approach allows the study of plants with unequal number of manipulated and controlled variables and the investigation of cases with saturation of manipulated variables and hard bounds on the controlled variables.