Pipeline Impact and Leak Location Method Based on Distributed Fiber Bragg Grating Sensing Network

Abstract

The invention relates to a pipeline impact and leakage locating method based on a distributed FBG (Fiber Bragg Grating) sensing network, and belongs to the technical field of sensing application of an optical fiber sensor. The method comprises the steps of establishing a sensing probe based on a cantilever structure by combing two FBGs with the same performance parameters; removing the environment temperature interference according to the same temperature and different strains of an environment where the FBGs at two sides of the sensing probe are located so as to simultaneously increase the sensitivity of the sensing probe; establishing a leakage detection sensing layer by adopting polymer to be combined with an elastic plastic thin film; conducting tiny deformation by using a smooth and easy-to-bend metal wire to solve the limitation of an installation position of a traditional FBG pipeline detection sensor and simultaneously increase the sensitivity of a sensing system; taking a difference value of wavelength shift distances of the FBGs at two sides of the sensing probe as a sensing signal, and seeking two probes with the largest sensing signal variable quantities and combining the distance between the two probes to realize dangerous point location.

Description

technical field [0001] The invention belongs to the technical field of sensing applications of optical fiber sensors, and relates to a pipeline impact and leakage positioning method based on a distributed optical fiber grating sensing network. Background technique [0002] Fiber Bragg grating (FBG) sensor has the advantages of small size, high sensitivity, wide dynamic range, anti-electromagnetic interference, corrosion resistance, high reliability, easy serial multiplexing, and does not affect the structural characteristics of the host material, etc., and is widely used In aerospace, shipbuilding industry, civil engineering, petrochemical industry, nuclear industry and medical engineering and other fields. [0003] With the development of my country's economy, a large number of oil pipelines have been established for the transportation of energy such as oil and gas. Due to pipeline aging, natural disasters and illegal intrusion, leakage incidents have occurred frequently, ...

AI Technical Summary

Problems solved by technology

The direct detection method mainly uses a polymer that smears on the outside of the FBG sensor and reacts with the material transported in the pipeline. When a leak occurs, the leaked material reacts with the polymer on the FBG surface to cause strain. By detecting the shift of the center wavelength of the FBG reflection spectrum Realize the detection and location of the leakage point. This method has high requirements for the placement of the FBG. Generally, it must be placed at the bottom of the pipeline to ensure that the leaked substance can contact the polymer on the FBG surface. At the same time, in order to achieve real-time monitoring, It is necessary to lay dense sensors along the pipeline, and the cost of the sensing system is high; the indirect detection method mainly combines the microbending effect of the optical fiber to attach a polymer sensitive to the material transported in the pipe on the optical fiber between the gratings. When a leak occurs, the polymer contacts The expansion reaction of the leaked substance causes the optical fiber to bend, resulting in a significant decrease in the reflected light intensity of the FBG behind the leak point, so as to detect the danger of leakage and locate the leak point. This method effectively reduces the number of sensors used and the cost of the detection system. But its positioning accuracy has been seriously affected

At the same time, because FBG is very sensitive to temperature and strain, most of the existing FBG detection methods do not consider the influence of environmental temperature changes on the detection results, resulting in low measurement accuracy of the sensing system, and it is difficult to detect pipeline damage caused by external shocks and other factors. Early warning and positioning of hidden danger points for structural damage

Images