Effect of Dynamic Operation Behavior on Quantitative Risk Assessment for Gas Treatment Unit of Gas Oil Separation Plant

After introduction of quantitative risk assessment (QRA) to chemical process in late 1970s, the number of accident had reduced for about two decades. However, it increases more than minimum value and shows non-uniform trend, because of population growth and facilities’ deterioration. Especially, complexity for high performance processing system have a great effect on occurrence of accidents. Thus, it is necessary to analyze risk considering complex operation condition. However, the problem of present QRA is that consequence is calculated only based on static operation conditions. Also, during past decade, dynamic risk assessment has solely focused on updating failure frequency according to failure data. Theses researches cannot reflect operation condition changes such as pressure, temperature, and flow rate.

In this study, influence of the operating condition change is focused and reflected to both frequency and consequence assessments. First of all, methodology for applying change of normal conditions (flow rate, pressure, and temperature) is presented. The minimum and maximum conditions are determined according to design basis. It is assumed that distribution of conditions follows beta distribution. This methodology is applied to existing gas treatment unit (GTU) in gas oil separation plant (GOSP). And then, QRA is conducted for each three changes. In this GTU process, distributions of pressure and temperature affect risk, and risk integral increases by 47.7% respectively. This paper contributes to recognize importance of considering dynamic operation behavior in QRA.