Vol. 19, No. 04, pp. 467 - 474, October - December 2002
ISSN 0104-6632 Printed in Brazil
AN MILP FORMULATION FOR THE SCHEDULING OF MULTIPRODUCT PIPELINE SYSTEMS
R.Rejowski Jr. and J.M.Pinto*
Department of Chemical Engineering, University of São Paulo, USP, Av. Prof. Luciano Gualberto, Travessa 3, 380, 05508-900, São Paulo - SP, Brazil. E-mail:firstname.lastname@example.org E-mail: email@example.com (Received: March 5, 2002 ; Accepted: May 27, 2002)
Abstract - Pipelines provide an economic mode of fluid transportation for petroleum systems, specially when large amounts of these products have to be pumped for large distances. The system discussed in this paper is composed of a petroleum refinery, a multiproduct pipeline connected to severaldepots and the corresponding consumer markets that receive large amounts of gasoline, diesel, LPG and aviation fuel. An MILP optimization model that is based on a convex-hull formulation is proposed for the scheduling system. The model must satisfy all the operational constraints, such as mass balances, distribution constraints and product demands. Results generated include the inventory levels atall locations, the distribution of products between the depots and the best ordering of products in the pipeline. Keywords: pipeline, scheduling, logistics, distribution planning, optimization.
INTRODUCTION Planning and scheduling activities related to product distribution have been receiving growing attention since the past decade. Every company should focus on attending all its clientrequirements at the lowest possible cost. As a matter of fact, transportation costs had already surpassed 400 billions dollars in the early eighties (Bodin et al., 1983). Petroleum products can be transported by road, railroad, vessels and pipeline. The latter has usually been utilized for crude oil transportation from terminals to refineries (Mas and Pinto, 2002). Pipeline transportation is the mostreliable and economical mode for large amounts of liquid and gaseous product. It differs from the remaining modes, since it can operate continuously (Sasikumar et al., 1997). For the past forty years, pipelines have mainly been utilized by the petroleum industry for transportation of petroleum and its derivatives.
*To whom correspondence should be addressed
Shobrys and White (2000) and Katzer etal. (2000) mention the importance of MINLP models for the programming of operations in oil refineries because of the inherent nonlinearities of chemical processes and the possibility of representing discontinuous functions and operational decisions. Pinto et al. (2000) present optimization models for planning and scheduling in petroleum refineries. Shah (1996) presents an MILP for crude oilscheduling in a system consisting of a port connected to a refinery by a pipeline. Moro and Pinto (1998) studied the efficiency of an MILP for the allocation of crude oil to tanks. Sasikumar et al. (1997) describe a scheduling problem that concerns a pipeline that receives products from a refinery and supplies several depots connected to it. The pipeline is the only system that can transport severalpetroleum derivatives, and therefore the refinery must efficiently store the minimize product various products and contamination. Techo and Holbrook (1974) also illustrate simplified models for transportation of
Rubens Rejowski Jr. and José M. Pinto
crude oil and petroleum products in complexes with multiple pipelines. The system considered in this work is composed of a petroleumrefinery, a multiproduct pipeline and several depots that are connected to local consumer markets. Large amounts of oil derivatives that are generated in the refinery must be pumped for long distances until they reach their destinations. The major obstacles faced in these operations are concerned with the satisfaction of product demands by the various consumer markets and the large variation of the...