The Marsden Point Oil Refinery is owned and operated by the New Zealand Refining Company. The plant receives crude oil and refines it. One of the main operations is blending materials from component tanks into a final product tank. A decision tool has been created to determine which pumps should be assigned to which tanks, in order to minimise the blending time for materials at the Marsden Point Oil Refinery. This is subject to constraints on which pumps can be used for which tanks and how fast the pumps can operate.

Presently the pump allocation is performed manually where each operator has their own heuristic, which they apply to achieve the objective of minimising the blend time. Although these methods may work, they are not consistent and may not always achieve the optimal result. The decision tool, which has been designed, gathers information such as what materials are in which tanks, the volumes of the tanks and the viscosity of the tanks from the existing spreadsheet.

This information is put into a formulation for a mixed integer program. Then the formulation is solved using solver in Microsoft Excel. The information about the pump to tank combinations is collected and pasted into the existing spreadsheet for the operator to see the final allocations of the pumps, the final flow rates for the pumps and the final time taken to empty the tanks.