(32cx) Enhancing the Reliability of Interlock in HF CCSS Acqc through Safety Integrity Level Study

SIL studies were conducted during the design phase of the new line P4 Phase 2 to ensure the safety of the process by evaluating various safety devices of the process using acute toxic substances. In particular, SIL evaluations were conducted on the Safety Instrumented Functions (SIF) loop of the Central Chemical Supply System (CCSS) that stores acute toxic substances, HF, in a large capacity tank.

The study used Layer of Protection Analysis (LOPA) and Computational Fluid Dynamics (CFD) to evaluate the need for control safety functions for all identified accident scenarios and determine the SIL rating value. This involved calculating the final frequency by considering independent protective layers (IPL) such as safety valves, rupture discs, and CCTV monitoring, and deriving the required Probability of Failure on Demand (PFD). In addition, a 3D CFD simulation was performed to predict pressure changes inside the tank and to suggest ways to improve the safety of the system based on this.

In conclusion, this paper evaluates the SIL study to improve the safety of the interlock system of the HF CCSS ACQC process. Through SIL studies, it is possible to improve the reliability of interlock systems that can improve the safety of the process based on international standards such as IEC61508, IEC61511, and the company's operating status. It is important to evaluate SIL ratings and design and implement interlock systems based on them, and to continuously monitor the status of the interlock system through a real-time monitoring system and take prompt action in case of problems.