Underground pipeline leakage early warning system and method based on fiber grating sensor

Abstract

The invention discloses an underground pipeline leakage early warning system based on fiber bragg grating sensors and a method thereof. The system comprises an underground pipeline, the fiber bragg grating sensors fixed to the outer wall of the underground pipeline and a transmission optical cable connected with the fiber bragg grating sensors. The transmission optical cable is sleeved with a protection casing pipe. Sensor holes are formed in the outer wall of the bottom of the protection casing pipe. The fiber bragg grating sensors stretch out of the protection casing pipe through the sensor holes and are fixed to the outer wall of the underground pipeline. The positions corresponding to the fiber bragg grating sensors are respectively provided with a manhole so that the fiber bragg grating sensors and the transmission optical cable can be conveniently replaced and maintained. Each fiber bragg grating sensor is formed by connecting a fiber bragg grating strain sensor with a fiber bragg grating temperature sensor in parallel. The strain and the temperature of the outer wall of the underground pipeline are monitored at the same time at each monitoring point, two-dimensional reaction to a leakage event is achieved, and the hidden danger of leakage of an underground pipe network can be monitored more accurately and effectively.

Description

technical field [0001] The invention relates to an underground pipeline leakage early warning system, in particular to an underground pipeline leakage early warning system based on a fiber grating sensor, which is used to realize accurate automatic early warning of underground pipeline leakage and facilitates replacement and maintenance of the entire system. Background technique [0002] With the improvement of social economy and people's living standards, there are more and more various building groups, and the underground pipelines such as pipelines such as water, electricity, heating, and gas, electric wires and cables, and communication optical cables are extended underground. In order to prevent re-construction or burying other facilities when excavating trenches, digging underground pipes, lines and other buried objects, the applicant applied for a utility model patent "underground pipeline identification belt" with the authorization announcement number CN2745074Y on No...

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Problems solved by technology

[0008] In the article "Fiber Bragg Grating Temperature and Strain Sensing System Applied in Oil and Gas Pipeline" published in "Laser Technology" Volume 31 Issue 1 in February 2007, a fiber grating temperature sensor is installed at the entrance and exit respectively. Install a pressure sensor in the station to obtain the variation of crude oil pressure and temperature in the oil and gas pipeline, so that according to different strain and temperature values, corresponding measures such as heating, pressurizing or decompression are taken in the station to ensure that the crude oil is in the oil pipeline. However, this kind of system can only detect the situation when a large amount of oil and gas has leaked, and cannot timely predict the leakage in the early stage; in October 2013, the article "Based on In "Study on On-line Corrosion Detection System of Oil and Gas Pipeline with Fiber Bragg Grating Sensor in Short Grid Area", fiber grating strain sensors are arranged along the outer surface of the oil and gas pipeline along the circumferential direction to monitor the circumferential strain of the oil and gas pipeline, thereby monitoring the corrosion of the oil and gas pipeline and preventing oil leakage

However, this system only monitors a single temperature or a single strain for each measurement point, the monitoring data is too single, and the false alarm rate is high

In the Chinese invention patent "A Fiber Bragg Grating Sensing Test System for Oil and Gas Pipeline Detection" with the authorized notification number ZL03137597. In this system, when the fiber grating sensor or transmission fiber fails, it will not be able to complete the replacement, resulting in the problem that the oil and gas pipeline cannot be reused

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