A multi grid discrete time based framework for maritime distribution logistics & inventory planning for refinery products

Abstract

In this paper, a mixed integer linear programming(MILP) framework is presented to rigorously represent a maritime inventory routing problem(MIRP). The MIRP discussed here involves multiple refinery liquid products that need to be transported from multiple supply ports to associated consumer ports using ships with undedicated compartments. The model is based on VMI(vendor managed inventory) system where the vendor decides the product delivery quantity and time of delivery by tracking the consumer inventory and consumption patterns. The proposed mathematical framework involves a multi grid discrete time formulation which rigorously represents several intricacies related to products loading/unloading, jetty activities, port inventory limitations and ship voyages. Several scenarios representative of the actual process are designed and the results demonstrates the efficacy of the proposed framework in finding an optimum ship and jetty schedule that minimizes the total transportation cost in a computationally efficient manner.