Real time optimization with multivariable control is required to maximize profits

Optimization of an operating process unit performed in real time with an on-line process control computer has a number of significant advantages over an optimization executed by an off-line computer. These advantages are derived from the process control computer's abilities to know precisely the current state of the operation, to control the process at the set of interacting constraints representing the predicted future state of the operation, and to provide direct feedback on how valid the predictions actually are. Multivariable interactive computer control techniques which recognize constraints are required to hold the process at its most profitable operating conditions.