Simultaneous Design, Scheduling and Operation Through Process Integration

Abstract

Processing facilities are normally designed with sufficient flexibility to handle nominal variations. When the process features planned changes in feedstock and products, scheduling is often used to optimize process operation. The objective of this dissertation is to develop a new approach to design and scheduling with economic, environmental, heat integration and inherently safer design objectives. Specifically, this work introduces a systematic framework and the associated mathematical formulation for simultaneous process design and scheduling while simultaneously addressing economic, environmental, heat integration and inherently safer design objectives. Therefore, more than one type of proper tradeoffs are established between these objectives. The environmental issues pertaining to the parameterized process retrofitting, scheduling, and operation strategies are simultaneously considered along with the environmental impact of these changes. Similarly, the design synthesis of heat-exchange networks (HENs) is addressed in the context of optimizing energy consumption under scheduling scenarios. Finally, the goal of inherently safer design is simultaneously considered with the expected schedules of the process. Several optimization formulations are developed for the projected schedules while allowing design modifications and retrofitting changes. The modifications and changes include new environmental management units, synthesis of flexible and optimal HENs, and design of an inherently safer process. Process models with the appropriate level of relevant details are included in the formulations. A discretization approach has been adopted to allow for a multiperiod optimization formulation over a given time horizon. The resulting framework identifies opportunities for synergism between the economic, environmental, heat integration and inherently safer design objectives. It also determines points of diminishing return beyond which tradeoffs between the above mentioned objectives are established. The devised procedure is illustrated with case studies.