1 A Discretization-Based Approach for the Optimization of the Multiperiod Blend Scheduling Problem Scott P. Kolodziej, a Ignacio E. Grossmann, a* Kevin C. Furman, b and Nicolas W. Sawaya c a Department of Chemical Engineering, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh PA, 15213, USA b ExxonMobil Upstream Research Company, 3120 Buffalo Speedway, Houston, TX 77098, USA c ExxonMobil Gas & Power Marketing Company, 800 Bell Street, Houston, TX, 77002, USA Abstract In this paper, we introduce a generalized multiperiod scheduling version of the pooling problem to represent time varying blending systems. A general nonconvex MINLP formulation of the problem is presented. The primary difficulties in solving this optimization problem are the presence of bilinear terms, as well as binary decision variables required to impose operationalconstraints . An illustrative example is presented to provide some insight into the difficulties faced by applying conventional MINLP approaches to this problem, specifically as it pertains to finding feasible solutions. A radix-based discretization scheme is developed with which the problem can be reformulated approximately as an MILP, which is incorporated in a heuristic procedure and in two rigorous global optimization methods. and requires much less computational time than existing global optimization solvers. Detailed computational results of each approach are presented on a set of examples, including a comparison with other global optimization solvers. 1. Introduction The efficient blending of liquid fuels to meet both technical and environmental specifications has been a growing research area in recent years as stricter regulations and smaller profit margins * Corresponding author. Tel.:+1 412 268 3642; fax:+1 412 268 7139. E-mail address: grossmann@cmu.edu (I.E. Grossmann).