Multi-objective optimisation for safe multi-floor process plant layout using the Dow’s Fire & Explosion Index

In this work, we propose a multi-objective mixed-integer linear programming (MILP) model for evaluation of safe multi-floor process plant layout using the Dow’s Fire & Explosion Index (F&EI). Two objectives are considered, namely the total monetary cost and the financial risk, and solved via the ε-constraint method. The total monetary cost consisted of the piping costs, horizontal and vertical pumping costs, land purchase cost, fixed and area-dependent floor construction cost, and the cost of protection devices. The financial risk was evaluated as the maximum probable property damage cost obtained using the F&EI evaluation procedure. The proposed model was applied to an ethylene oxide plant consisting of 7 equipment items with Pareto-optimal solutions showing that the financial risk can be greatly reduced by layout reconfiguration without the need for protection devices and their associated monetary costs. Further increase in the safety levels of the plant can then be achieved through protection device installation at a cost. These, and more information obtained, which are non-existent in previous single objective considerations, are helpful for a more informed decision making process in the planning stages of the design of chemical process plants. •A bi-objective MILP model for the multi-floor plant layout problem with safety is developed using the Dow’s F&EI.•Safety distances used for risk quantification are estimated as the Tchebychev distance between item boundaries.•Objectives considered include the total monetary cost and the financial risk.•Results obtained showed layouts with lower financial risk when compared to single objective considerations.