A Study on Optimal Layout of On/Offshore Chemical Process Considering Domino Effects Based on Hierarchy Procedure and MILP

Abstract

This thesis presents optimal layout generation and its application considering the method of criteria application to prevent accident propagation and the structural stability in the offshore plant. In the chemical plant, fire and explosion accidents occur because of the harsh operation condition and hazardous materials. Sometimes these accidents can be expanded to disaster by damage to human or properties. Thus, the risks of the chemical plant have to be considered from the design step. The developing location of the buried energy is also moving farther away from inland, and the offshore platform is spotlighted and studied more for exploitation and the corresponding safety improvement. The objective of this thesis is to propose a new method to determine the optimal layout preventing the chain reaction of accidents called domino effects and considering the stability of offshore platform. In this thesis, the methodology is suggested to improve the safety by proposing the mathematical programming-based procedure using MILP model. Also, the hierarchy procedures including main factors to be considered, which can be applied to the on/offshore plants, are suggested. The proposed methodology is verified by applications to practical case studies, which are being used or will be adopted in the onshore and offshore industries, such as the ethylene oxide production process as an onshore process in the chemical industry, the top-side of CO2 carrier as a single-floor offshore plant to be used in the Korea, and the mixed refrigerant cycle of the LNG liquefaction system on the top-side of LNG-FPSO as multi-floor offshore process for gathering the energy. Before the determination of the optimal layout, the distance related to the risks in the process is calculated from quantitative risk assessment to estimate the effects of possible accidents. In case of offshore platform, considering the structural constraints, overall weight balance is added to satisfy the proposed criteria for stability of the whole plant and it would be beneficial to select the proper distribution of equipment. The results of the case studies showed satisfying the proposed risk criteria for preventing the domino effects between the equipment under the given constraints. The suggested method in this thesis contributes to helping the systematic determination of sustainable layout of chemical processes by reducing the damage to equipment and increasing structural stability of the offshore platform.