混合式光纖干涉儀作為船舶管線偵漏系統

A Hybrid Fiber Optic Interferometer as a Pipelines Leak Detector for Ships

Pipelines are used very often for transportation of liquid materials in the cabin of a ship. If a leakage takes place on a pipeline without being noticed in time, it will cause a lot of loss of material. Sometimes, a disaster may happen. Hence, for safety reason, once a leakage happened, it is very important to detect the location of the leakage and fix it as soon as possible. However, it is a tough job looking for the location of leakages among so many pipelines within a crowded space. Compare to those traditional electromechanical sensors with coaxial cable as the communication medium, the fiber optic sensor system offer lower transmission loss with immunity of electromagnetic interference (EMI) relative to its counterpart. Also, if the sensitivity is concerned, we have to consider the implement of a fiber optic interferometer. In this paper, a hybrid configuration of Mach-Zehnder and Sagnac fiber optic interferometer was proposed. In this hybrid interferometer, because the propagation of the two light beams pass through the leaky position at different time, a phase different is induced. We demodulate the interference signal by a phase generated carrier (PGC) scheme and the leaky position can be calculated. The accuracy of this method can reach 99.9% for the localization of the leaky location. 每艘船上都佈滿各式各樣的管線，作為能源、物質或動力輸送的管道，這些管道一旦產生洩漏，常引起相當大的損失，甚至於產生巨大的災變，然而由於洩漏位置的不確定性以及船艙的狹窄空間，使得要在密佈林立的管線間，進行洩漏位置的偵測，成為一件相當棘手的工作。本文利用光纖線細、質輕、不畏電磁平擾及低傳輸損失的特性，同時藉光纖干涉儀的靈敏特性，結合成一有效的管線偵漏系統，經由初步測試，其位置之精確度可達99%。