Operators of LNG liquefaction and gasification terminals have a responsibility (and are required by local regulators) to prevent major accidents and to limit the consequences of any accident to people and the environment. Regulatory requirements typically cover the loading/unloading equipment at the jetty, the site itself and the pipeline link to the national gas transmission system. Typical Emergency Shut-Down (ESD) systems are required to shut down within I minute of the occurrence of a leak in any plant area, unloading equipment at jetty or pipeline. Traditional leak detection technologies have historically not been well-suited to this requirement. Measuring the temperature distribution around the plant is a powerful tool for leak detection, monitoring tank base heating and the cool-down process. This paper will describe the application of distributed temperature sensing (DTS) employing a fiber optic cable, generally deployed alongside or within LNG tanks, tank bases or pipelines to provide continuous temperature monitoring along its length. A single system can hence provide leak detection functionality for pipes and tanks, monitor the initial cooldown process, and also monitor tank base heating on an ongoing basis. Benefits of this approach include enhanced plant safety, minimized downtime and improved plant performance. The system also helps operators to conduct detailed intelligent monitoring operations that reduce the likelihood of undetected leaks and plant damage while optimizing efficiency. The paper will also describe SIL2 (Safety Integrity Level 2) configurations and will include recent case studies of installations of this type including the recently installed SLNG.
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