Scheduling of Actual Size Refinery Processes Considering Environmental Impacts with Multiobjective Optimization

Abstract

This paper deals with the scheduling problem of refinery processes considering environmental impacts. To keep abreast of rapidly changing business circumstances, the effective scheduling of the objective of which is to maximize the total profit is absolutely needed for large-scale plants such as refinery processes. In addition, companies cannot avoid making an effort to reduce environmental impacts because now people have a much better understanding of the environment. However, the two objectives mentioned above are conflicting. There is no way to maximize the total profit and minimize environmental impacts simultaneously, but a tradeoff exists. In this case, the best way is to obtain Pareto optimal solutions by multiobjective optimization. Plotting Pareto optimal solutions, decision makers are able to know the correlation between the two objectives. The selection of one of the Pareto optimal solutions depends largely on the decision makers. In this paper, a mixed-integer linear programming model is developed for solving the scheduling problem of actual size refinery processes. Critical Surface-Time 95 (CST95), an impact assessment methodology, is used for considering global environmental impacts. The ε-constraint method is used in order to implement multiobjective optimization. Finally, this paper proposes Pareto optimal solutions and shows the optimal scheduling of an arbitrary point in Pareto optimal solutions compared with the total profit maximization problem.

Sustainable process design by the process to planet framework

“…The majority of more recent SPD studies consider single environmental objectives, with the most common being Eco‐Indicator 99, greenhouse gas emissions, and GWP . Multiobjective optimization techniques are used to locate designs that offer compromises between the economic and environmental objectives and are occasionally applied to identify trade‐offs between multiple environmental objectives …”

Decision-making for Petrochemical Planning Using Multiobjective and Strategic Tools

“…These solutions, although not being simple, contain in their steps the simple MO methods discussed earlier. However, some authors solved MO with MILP models using simple methods; Chang and Wang (1996) used the weighted Lp norm for a solid waste management system, Song et al (2002) used the 1-constraint for scheduling a refinery, Bagajewicz and Cabrera (2003) used the 1-constraint for design and upgrade of instrumentation network and Bonfill et al (2004) used the weighted method for scheduling batch plants.…”

“…Many economical objectives were used in industry planning. Examples are: minimum cost (Fathi-Afshar and Rudd, 1981;De Santiago et al, 1986;Bagajewicz and Cabrera, 2003); maximum profit (Song et al, 2002;Bonfill et al, 2004); maximum net present value (Rodera et al, 2002). On the other hand, many safety or hazard indices were used for planning.…”

Multiobjective evolutionary optimization of batch process scheduling under environmental and economic concerns

“…The work of Song et al considers the scheduling problem, modeled by a MILP formulation, of a refinery process taking into account the environmental impact. The ε‐constraint method is used to obtain a set of Pareto solutions for the multiobjective optimization that considers global environmental impacts by means of the critical surface‐time 95 assessment methodology.…”