Risk-based Process Safety Management in Industrial Process System

Abstract

Quantitative risk management was introduced to industrial process system at the late 1970s. At first, the number of incidents has decreased drastically until 1995, but after that time it shows an irregular pattern and even grows more than minimum value. Not only the growth of plants number and facilities deterioration affect on the number of accidents, but also operating conditions, which get complex for reducing energy or cost per product, have a strong influence on it. Furthermore, consequence of accidents increases because of population growth. Thus, an effective method for process safety management is necessary. Also, to be efficient, it should be specific for each system. This thesis addresses risk-based process safety management in industrial process system. It is composed of storage, transportation, and process parts, and each process deals with solid, liquid, and gas phase materials respectively. First part is coal silo. Due to the fact that coal stacked in the open air not only causes environmental issues, but also degradation in quality, coal became to be stored in a silo. However, the confined nature of the silo stimulated many coal dust explosions and these explosions has been repeating. Thus, to prevent these accidents, detailed cause of a specific dust explosion in silo is analyzed according to the pentagon of dust explosion in terms of design and operation of the silo. After presenting the general properties of coal dust and explosion cases, coal of a scene of the accident is compared. Through cause analysis, it is reasoned that what should be prepared or how to operate coal silo. Second part is transportation through underground pipeline. Due to the long term usage and irregular maintenance for corrosion checks, catastrophic accidents have been increasing in underground pipelines. In this study, a new safety management methodology of underground pipeline, risk-based pipeline management, is suggested reflecting corrosion effect. First, principle of the risk-based pipeline management is suggested compared with an original method, qualitative measure. It is distinguished from the existing method by reflecting societal risk and corrosion in safety management of underground pipeline. And then, it is applied to an existing underground propylene pipeline in Ulsan Industrial Complex, South Korea. As a result of applying the risk-based pipeline management, risk integral is reduced by 56.8% compared to the qualitative measure. Finally, sensitivity analysis is conducted on variables, which affect the risk of the pipeline. This study would contribute to introduce quantitative measure to pipeline management and increase safety of pipeline. The last part is gas treatment unit (GTU) in gas oil separation plant (GOSP). QRA only considers normal operating conditions so far. However, real plants are operated with variables trip. The objective of this study is to identify the effect of operating condition change on QRA. The methodology of dividing operating condition is introduced and applied to the GTU process. As a result, flow rate change barely affects on FN-curve. However, the changes of pressure and temperature increase the risk to 147% of normal condition with GTU process in GOSP. Thus, it can be concluded that when a process deals flammable material of high pressure or high temperature, QRA should reflect operating condition change. This study could contribute to improve accuracy of QRA.