Process plant layout optimization with uncertainty and considering risk

•Introducing an integrated approach for process plant layout problem with concurrent consideration of economic and safety aspects.•Developing a new mathematical model for Facilities Layout with considering domino hazard score for different fire and explosion scenarios and probability of death for toxic release.•Calculating damage probability function for overpressure caused by facility explosion, using probit functions.•Considering various risk indexes which extracted from the safety engineering and chemistry fields.•The applicability of the results that have been validated in the case study (Iran's South Pars gas field).

Facility layout is an important factor in designing of process plants such as petrochemical units and refineries. An appropriate design of layout ensures proper performance of corresponding departments as well as providing an equilibrium between large number and sometimes inconsistent structural design constraints. In this research, a mixed integer non-linear programming (MINLP) formulation is proposed for process plant layout problem, considering the toxic release risk and possible scenarios of fire, explosion and the domino effects of them. Then the Bat metaheuristic algorithm was employed to solve it. Finally, the model was implemented on 6th refinery, unit 101 of Iran's South Pars gas field, and the results showed the effectiveness of the model, in costs reduction and safety improvement.