955 CHEMICAL ENGINEERING TRANSACTIONS Volume 21, 2010 Editor J. J. Klemeš, H. L. Lam, P. S. Varbanov Copyright © 2010, AIDIC Servizi S.r.l., ISBN 978-88-95608-05-1 ISSN 1974-9791 DOI: 10.3303/CET1021160 Please cite this article as: Al-Mutairi E. M., (2010), Optimal design of heat exchanger network in oil refineries, Chemical Engineering Transactions, 21, 955-960 DOI: 10.3303/CET1021160 Optimal Design of Heat Exchanger Network in Oil Refineries Eid M. Al-Mutairi Chemical Engineering Department, King Fahd University of Petroleum & Minerals Dhahran 31261, Saudi Arabia mutairi@kfupm.edu.sa The performance of the heat exchanger network (HEN) in a plant is an important aspect of energy conservation. Pinch technology and mathematical programming techniques offer an effective and practical method for designing the HEN for new and retrofit projects. The fluid catalytic cracking (FCC) is a dominant process in oil refineries and there has been a sustained effort to improve the efficiency and yield of the unit over the years. HEN optimal design in FCC process is an essential element in reducing the cost and improving the process as a whole. The objective of this work is to introduce a systematic procedure for designing optimal and flexible FCC-HEN that incorporates variations in feed flowrates and specs, and on same time considers different schedules imposed on the process. First, a hierarchical approach consisting of a general optimization formulation that is accounting for the anticipated schedules and heat integration during the FCC-HEN design phase will be used in this project. Then, a new targeting approach will be introduced because of the complexity of the formulation for heat integration with varying flows and temperatures. Finally In order to synthesize a flexible configuration of the FCC-HEN, a multiperiod formulation will be developed and applied on FCC process to account for the variations associated with the anticipated operational schedules. 1. Introduction Fluid catalytic cracking (FCC) is an important process in oil refineries. It converts atmospheric gas oil, vacuum gas oils, certain atmospheric residues and heavy stock recovered from other refinery operations into high-octane gasoline, light fuel oils and olefin rich light gases. Heat exchanger network (HEN) in FCC process can be optimized using pinch technology, mathematical programming, combination of both or stochastic methods. There are two ways for considering HEN design which are based on either sequential or simultaneous approaches. The sequential approaches are taking in consideration fixed supply and target temperatures while the simultaneous approaches are considering other design aspects simultaneously with the optimal design of HEN. Over the past 30 years, significant research contributions have been made in developing design techniques for the synthesis of heat exchange networks (HENs) in general. Much of this work has focused on heat integration as the overarching goals with objectives