Optimizing detailed schedules of a multiproduct pipeline by a monolithic MILP formulation

A multiproduct pipeline is an economical way for transporting several products from a single source to multiple delivery stations over a long distance. This paper addresses how to optimize detailed schedules of a multiproduct pipeline. A discrete-time mixed integer linear programming model is developed, which adopts a novel objective function to seek the minimum summation of pumping rate variations in every pipeline segment along a pipeline during a scheduling horizon. The feasibility of the new objective function is demonstrated in theory. A conclusion is drawn that the more stable pumping rate of a pipeline segment is, the lower frictional loss for pumping products is. Besides operational constraints, two sets of special constraints are introduced into the model for improving the operability and practicability of detailed schedules. One is the stopping and running duration limitations of injection operations and another one is the flow rate stability requirements of injection and delivery operations. The proposed MILP model is successfully tested on two real world multiproduct pipelines using CPLEX as solver.