為了降低化工廠意外事故所造成的損失，通常都會在程序單元中安裝保護系統。由於感測器與停俥閥件的故障是隨機事件，故保護系統的可用度是與元件配置和維修策略息息相關的。本研究的目的為改善過去發展出的設計及維修步驟(Liang and Chang, 2008)，具體言之，即將警報系統中感測器之修正型維修策略擴展為同型備件可互相支援之模式，並針對多重管道的保護系統，發展出數學規劃模式，以期能將總期望支出成本最小化，並且得到最佳的感測器與關斷元件配置、相應的修正型及預防型維修策略、與警報及關斷邏輯。最後，我們針對三個化工程序做深入案例研究，以展示此模式之可行性與有效性。

In order to mitigate the undesirable effects caused by accidents in chemical plants, it is a common practice to install protective systems on processing units operated under hazardous conditions. Since the failures of sensors and valves are basically random events, the reliability (or availability) of the protective system is highly dependent upon the structural characteristics and also the maintenance policies of alarm and shutdown systems. The aim of this study is to improve the current practice in designing and maintaining protective systems (Liang and Chang, 2008). In particular, the corrective maintenance policy for the sensors is extended to allow common spares and, also, the design options of multi-channel alarms are incorporated in an integrated mathematical model to minimize the total expected expenditure. By solving this model, the optimal configurations of sensors and shutdown units, the best corrective and preventive maintenance policies and alarm/shutdown logics could be identified. Three examples are provided in this thesis to demonstrate the feasibility and effectiveness of the proposed approach.

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