(302c) Smart Plant Approach to Increased Plant Profitability

In the context of process control it is proposed that Smart Plant Operation refers to the automated retuning of plant controllers based on updated information about disturbance characteristics with the overall objective of maintaining the highest plant profitability.

In this paper we will discuss two main concepts. The first is that an increased concern over plant economics has created an incentive for operation closer to the physical and safety limitations of the plant. As such, modern controller design methods must be aware of these limitations as well as the economic impact of not being able to satisfy all inequality constraints. In the case of an inability to meet all constraints, the design method must re-select the process operating condition such that all plant limitations can be observed. However, since there are numerous operating conditions that can achieve this goal, such a procedure should be guided by the economics of the plant so as to select the least costly alternative. In the proposed methodology we advocate operating point back-off as a measure of economic impact and constrained minimum variance control as a design method to reflect to automatically retune the controller.

The second main concept is the impact of disturbance characteristics on control system performance. Specifically, a change in disturbance characteristics (due to changes in the process or upstream units) will impact the controller's ability to satisfy the desired process limitations. Thus, a controller to be used within a Smart Plant (a Smart Controller) must be able to identify a change in disturbance characteristic and then retune itself such that physical and safety limitations continue to be observed and plant profit continues to be maximized. The above notions will be illustrated through a number of simple examples and simulation based case studies.