Incorporation Of Scheduling Considerations In Retrofitting Design Of Heat Exchange Networks Eid M. Al-Mutairi a and Mahmoud M. El-Halwagi b a Assistant Professor, Department of Chemical Engineering, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia b Professor, Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas 77843, USA The objective of this work is to introduce a systematic procedure for incorporating heat integration and process scheduling into the design phase. A hierarchical approach is developed. First, a formulation is developed to account for the anticipated schedules and heat integration during the design phase. Because of the complexity of the formulation for heat integration with varying flows and temperatures, a new targeting approach has been introduced. A linearization approach is adopted by discretizing the searched space for temperatures. Then, integer cuts are added to select the optimal temperatures. This results in a mixed-integer linear programming formulation for the targeting of minimum heating and cooling utilities for the various schedules. In order to synthesize a flexible configuration of the heat integration network, a multiperiod formulation is developed to account for the variations associated with the anticipated schedules. 1. Introduction With changing market conditions and demands, various industries must develop design and operating strategies that enable the cost-effective operation of the process while addressing several key objectives. Production schedules should be determined so as to increase revenue, enhance efficiency, and conserve natural resources. Proper heat integration in chemical plant is one of the essential strategies for an efficient operation and can lead to considerable cost savings. Over the past 30 years, significant research contributions have been made in developing design techniques for the synthesis of heat exchange networks (HENs). Much of this work has focused on heat integration as the overarching goals with objectives such as minimizing heating and cooling utilities and total annualized cost of the network. On the other hand, much less work has been done in the area of reconciling heat integration with other process objectives. Mathematical programming techniques have been effectively used to address several important categories of HENs. In an attempt to exploit the interactions between the process operating conditions (stream temperatures and flowrates) and the heat recovery network, Papoulias and Grossmann (1983) developed a strategy for simultaneous