A Profit Index for Assessing the Benefits of Process Control

In industrial processes, the potential benefit that arises from improved control is assessed before the installation of a new control strategy. Estimating the economic benefit motivates the investment in a new control system and minimizes the risk of the new technology not living up to its promises. In this paper, a method for a priori estimation of the benefit from improved process control is presented. The method builds on conventional estimation techniques and evaluates the performance function associated with the controlled variable by assuming a reduction in variance. Three frequently used performance functions, namely, a quadratic performance function, a linear performance function with constraints, and the so-called clifftent performance function, are investigated. The profit index as a function of the variance is computed, and the implications of a reduction in variance for each performance function are assessed. A further contribution of this article is the analytical derivation of the optimal op...