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12 October 2007 Development of an FBG-based low temperature measurement system for cargo containment of LNG tankers
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Proceedings Volume 6770, Fiber Optic Sensors and Applications V; 67700D (2007)
Event: Optics East, 2007, Boston, MA, United States
Given the growing demand for oil and natural gas to meet the world's energy needs, there is nowadays renewed interest in the use of liquefied natural gas (LNG) systems. For LNG to remain in its liquid phase, the gas has to be kept at cryogenic temperatures (< 160°C). And, as part of the LNG supply process, it becomes necessary to transport it using massive carrier tankers with cargo hulls operating at low temperatures and using special insulating double-wall construction. The safe and reliable storage and transportation of LNG products calls for low temperature monitoring of said containers to detect the onset of any potential leaks and possible thermal insulation degradation. Because of the hazardous nature of this cargo, only intrinsically-safe, explosion proof devices can be used. Optical fiber sensors-- such as fiber Bragg gratings-- are ideal for this application given their dielectric nature and multi-point sensing telemetry capability. In this paper, we describe the development of an on-line, multi-point FBG-based low temperature monitoring system based on a network of specially packaged FBG temperature and strain sensors mounted at critical locations within the inner hull, cofferdam and secondary barriers of a LNG carrier tanker. Given the stringent cryogenic operating temperature conditions, pertinent FBG designs, coatings and packaging approaches were formulated along with adequate installation techniques and integration of the interrogating FBG electronics into the tanker's overall SCADA monitoring system. FBG temperature sensors were demonstrated to be stable and sensitive over the 80-480K range. Stability is ± 0.25K or better with repeated calibrations, and long term stability at 480K is ~0.2mK/hour.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
D. G. Kim, W. Yoo, P. Swinehart, B. Jiang, T. Haber, and A. Mendez "Development of an FBG-based low temperature measurement system for cargo containment of LNG tankers", Proc. SPIE 6770, Fiber Optic Sensors and Applications V, 67700D (12 October 2007);

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