Detailed Scheduling of Operations in Single-Source Refined Products Pipelines

Abstract

The short-term scheduling of refined products pipelines is a very complex problem with many operational constraints to be considered. Available nondiscrete planning approaches just provide the input schedule and the set of aggregate product deliveries to be performed from in-transit lots to depots at every batch injection. To determine the sequence of individual cuts on each batch to be accomplished by the pipeline operator, it is still necessary to refine such an aggregate plan. To do so, new computational tools for efficiently generating the detailed schedule of single-source pipelines with multiple distribution terminals are presented. Two types of methodologies are proposed. On one hand, it is developed a continuous-time mixed-integer linear programming (MILP) formulation that seeks to minimize both the total flow restart volume and the number of single-delivery pumping runs over the planning horizon. In this way, substantial savings in energy consumption and pump maintenance costs are achieved. Effective solution strategies for the MILP model are also designed to deal with large pipeline scheduling problems. On the other hand, three different heuristic rules for selecting the receiving terminal are introduced. By applying those rules in combination with a discrete-event simulation model, not only alternative detailed schedules can be generated in a very short CPU time but also some of them are near-optimal solutions. Three instances of a case study aimed at finding the detailed schedule of a real-world single-source pipeline system are solved through the proposed optimization and discrete-event simulation methods. Results are analyzed to assess the quality of the generated solutions and the required computational costs.

Solution to a Pipeline Scheduling Problem by Using a Mixed Integer Linear Programming Model

“…In a published study by Cafaro et al, the researchers employed optimization and step function simulation methods in order to achieve detailed scheduling of a single source pipeline system (Cafaro et al, 2011).…”

Optimization model for the detailed scheduling of multi-source pipelines

“…Simulation models can validate the pipeline transportation plan by generating a detailed schedule based on different empirical rules (Cafaro et al, 2011;Gleizes et al, 2012). The simulation model regards the pipeline as a multi-server queuing system, with a single server at the end extreme of every pipeline segment.…”

“…An interesting feature of the simulation approach is that the detailed schedule is found at low computational cost, but its optimality cannot be guaranteed. Cafaro et al (2011) also solve the detailed scheduling problem for single-source pipelines through an MILP optimization model. At any time, a single depot can at most be receiving some amount of product from the line.…”

Optimal economic operation of liquid petroleum products pipeline systems

“…[28][29][30] Contemporary studies typically seek to minimize the energy used for pumping and incorporate engineering models of varying fidelity. 31,32 A variety of studies have examined time-dependent scheduling of single commodity transport, [33][34][35][36] various network topologies (i.e., single-and multi-source), 35,37 and optimization under uncertainty. 38 A recent formulation for optimizing flow schedules for crude oil pipelines has been proposed to minimize energy used for pumping and accounting for pipeline flow physics and pump engineering limitations.…”