Novel solution approach for optimizing crude oil operations

Abstract Scheduling of crude oil operations is a complex nonlinear problem, especially when tanks hold crude mixes. We present a new mixed‐integer nonlinear programming (MINLP) formulation and a novel, mixed‐integer linear programming (MILP)–based solution approach for optimizing crude oil unloading, storage, and processing operations in a multi‐CDU (crude distillation unit) refinery receiving crude from multiparcel VLCCs (very large crude carriers) through a high‐volume, single‐buoy mooring (SBM) pipeline and/or single‐parcel tankers through multiple jetties. Mimicking a continuous‐time formulation, our primarily discrete‐time model allows multiple sequential crude transfers to occur within a time slot. It incorporates several real‐life operational features including brine settling and tank‐to‐tank transfers, and is superior to other reported models. Notably our algorithm avoids concentration discrepancy and MINLP solutions by identifying a part of the horizon, for which its linear relaxation is exact, and then solving this MILP repeatedly with progressively shorter horizons. By using 8 h time slots and a hybrid time representation, an attractive approach to this difficult problem is presented.© 2004 American Institute of Chemical Engineers AIChE J, 50:1177–1197, 2004