Development and application of pneumatic-electric hybrid magnetic flux leakage detector for gas transmission pipelines

Abstract

[Objective] This paper focuses on developing a pneumatic-electric hybrid magnetic flux leakage(MFL) detector, examining and verifying its technical advantages to overcome challenges in using traditional air compressor-driven MFL detectors in both newly constructed long-distance natural gas pipelines and established pipelines with low fow rates or no transmission. [Methods] After analyzing the operational states of traditional air compressor-driven MFL detectors during inner pipeline detection, a dynamic model was constructed to simulate the motion of a pneumatic-electric hybrid inner detector within a pipeline, adhering to fundamental principles of detector mobility in gas pipelines. The MFL detector was enhanced with an active motor drive function to operate using both the blower and motor drive mechanisms. The motor was activated upon encountering abrupt changes in resistance, effectively addressing challenges such as detector blockages, pressure buildup, and acceleration caused by gas explosions, while ensuring smooth detector passage through the pipeline.[Results] The pneumatic-electric hybrid MFL detector developed in this study was used for the pre-commissioning inner detection of the Daqing-Harbin branch line of the China-Russia East-route Natural Gas Pipeline. It successfully detected various features at 6,930 positions along the 52 km pipeline. The subsequent excavation was performed at a position where metal loss was reported, confirming that all detection data, including defect location in mileage, type, ground positioning, length, width, depth, and clockwise direction, aligned with the excavation results. [Conclusion] The pneumatic-electric hybrid MFL detector has obvious advantages by using blower and its own power as the driving force, making it effective in practical engineering applications concerning safety, power performance, and data reliability. By integrating a low-pressure and low-fow blower, it effectively eliminates potential safety hazards commonly associated with high-pressure gas, prevalent in air compressor operations. The controllable speed feature ensures uniform detector movement, thereby improving data quality and detection accuracy. With the combined pneumatic and electric power, the detector navigates potential jamming points like crossings/spannings and bends swiftly, reducing the risk of blockages. This innovative detector shows promising application prospects,necessitating improvements in cost-effectiveness, system simplicity, and battery life.

Keywords

• long-distance natural gas pipeline
• magnetic fux leakage(mfl) detection of pipeline
• pneumatic-electric hybrid power drive