A Multiobjective-driven Approach to Reduce Risk in Process Layouts

Abstract

A multi-objective programming (MOP) approach is applied in this work to produce optimal facility layouts when some of the facilities may release toxic gas. A conflict appears when solving the optimization problem because reducing the occupied area increases the individual risk. In this approach, a utopia point is introduced as a reference, which is defined as the layout where no toxic releases are considered, i.e. the objective function consists on minimizing the total cost of interconnections and the occupied area. Then the Pareto set is built-up by incorporating individual risk to visualize the effect of the two contradictory objective functions. The closest point in the Pareto curve to the utopic reference is adopted here as the neutral risk point. A case-study is used to visualize risk-neutral, risk-averse and risk-seeking layouts where the overall stochastic individual risk is set up to a certain value. The optimization facility layout problem is formulated as a mixed-integer non-linear program (MINLP), which is highly non-convex.