The advantages of using distributed optical fiber temperature measurement in the online monitoring system of oil pipelines

Fiber optic temperature sensor, Intelligent monitoring system, Distributed fiber optic manufacturer in China

The importance of pipeline monitoring systems

In China, underground pipelines are indispensable material transportation facilities for important systems such as natural gas, oil, urban heating, and gas. It is of great significance for the development of the national economy and the transportation of energy and materials. At the same time, pipeline facilities have a huge investment and are mostly located in trenches or buried below the ground. They have a certain degree of concealment in space. If they are damaged due to human or natural reasons, it is difficult to detect them in a timely manner. The leakage of flammable and explosive substances will bring great safety hazards. If this causes a fire or explosion accident, it will bring huge economic losses, and even cause significant casualties and social disorder.

Measurement of steam temperature in power plants

Temperature measurement in power plants generally uses thermocouple devices, which are installed on the measured pipeline through temperature sleeves. The temperature sleeves are welded to the pipeline in the form of fillet welds, forming a closed communication space between the sleeve and the pipeline. The thermocouple passes through the sleeve and is exposed in the steam flow field inside the pipeline to achieve the purpose of measuring steam temperature. During the operation of the unit, high-temperature and high-pressure steam flows in the pipeline, and the flow rate of superheated steam is generally 40-50m/s. Due to the presence of the casing, the high-speed steam will continue to flow into the closed steam flow channel of the casing. As one end of the flow channel is closed, steam will form vortices at the closed end, which will cause blow and erosion on the inner wall of the casing, resulting in a thinning of the inner wall thickness of the pipe seat. Especially near the weld seam at the top of the closed steam flow channel of the casing, the deformation of the flow channel caused by the weld seam forms turbulent flow. Therefore, steam blow and erosion around the weld seam is particularly severe. In the actual operation of the unit, accidents of steam leakage caused by steam blow and erosion thinning of the casing often occur.

Distributed fiber optic temperature measurement system

The distributed fiber optic temperature measurement system based on Raman reflection is a new type of fiber optic temperature measurement technology developed in recent years. It has the advantages of ranging, reusability, high resolution, non-destructive alarm, output optical signal, anti electromagnetic interference, moisture-proof and anti-corrosion, and small error. Therefore, it can be used for temperature measurement in harsh conditions such as strong electromagnetic fields, high voltage, high current, flammable and explosive, and complex geometric environments. Due to the complexity and high economic cost of detecting defects caused by corrosion in oil pipelines in oil fields.

Distributed fiber optic sensing measurement technology

Distributed fiber optic sensing measurement is a technology that utilizes the principle of fiber optics to measure continuous lines. Fiber optic can serve as a sensing element and also a component for transmitting temperature. Fiber optic temperature measurement systems can continuously measure environmental parameters distributed along the entire length of the fiber, while obtaining the measured spatial distribution status and information that changes over time. If the optical fiber is laid along the pipeline as a sensing element, any point along the entire length of the optical fiber is a sensitive point, belonging to long-distance measurement. Theoretically, the sensing distance can be any length, the spatial resolution can be any size, the detection range is wide, and the characteristics of the optical fiber are not affected by electromagnetic interference, high sensitivity, high reliability, corrosion resistance, small volume, and many other advantages. It can meet the real-time online warning monitoring of various situations along dozens of kilometers of pipelines.

FJINNO has independently developed an online monitoring system for oil pipelines based on a distributed fiber optic temperature measurement system. It can accurately judge various types of defects on the inner wall of oil pipelines without damaging the pipeline, and accurately locate the spatial location of defects. The monitoring system can measure and obtain parameters such as temperature, pressure, and fluid velocity. By inputting these parameters into the experimental data fitting formula, the wall thickness at the defect on the inner wall of the pipeline can be accurately calculated. The development of this monitoring system is of great significance for the safe operation of oil pipelines.

Fiber optic monitoring device for pipeline vibration

Fiber optic vibration sensors can monitor and analyze municipal pipelines such as natural gas in real-time, enabling the detection and early warning of natural gas pipeline infringement incidents and the detection and analysis of damage and leakage points.
Pipeline vibration fiber optic monitoring system, including fiber optic sensors, fiber optic temperature measurement host, monitoring system, and alarm warning display screen, etc; Fiber optic sensors are fixed to the pipeline, including fiber optic cables laid along the pipeline and clamps used for installing fiber optic cables and forming a fixed connection with the pipeline; The sensing device includes a vibration collector for monitoring the vibration of fiber optic cables and a fiber optic thermometer for monitoring the temperature changes of fiber optic cables; The vibration collector and fiber optic thermometer are both connected to the monitoring controller signal, which is connected to the warning device signal and transmits warning information and sends warning commands to the warning device.