Study On Tracking And Locating Technology Of Spherical Inner Detector

Long oil and gas pipelines play an important role in economy development but pipeline accidents occur frequently in the recent years,and then the safety of pipelines has received more and more attention.The tiny leakage accidents of the pipeline caused by cracks,aging,and corrosion have become one of the major concerns for the pipeline security detection.To solve the puzzle of detecting and locating the tiny leakage of pipelines,our team has developed a spherical inner detector(hereinafter referred to as smartball)to cope with the tiny leak detection and positioning innovatively.Tracking and location technology refers to the internal staff can monitor the detector position in the pipeline by using equipment to ensure the success of leak detection,and then calculate the accurate position of the tiny leakage with the accelerometer in smartball.There are some great differences between the traditional pipeline inner detectors and smartball in the shape,structure and motion feature,and what's more,there are more limitations in the design of smartball.In this paper,some key techniques of the tracking and locating system for smartball have been studied.Firstly,some traditional tracking methods for inner detector have been summarized,and a novel tracking approach based on extremely low frequency electromagnetic is presented according to the limitations and of feature of smartball its own.Metal pipeline makes the most important influence to limit the transmission of the signal,so it is suggested only extremely low frequency electromagnetic signal that can penetrate the metal pipe in theory.A model of magnetic dipole is proposed to replace the transmitting antenna of electromagnetic signal,according to the engineering application,and as a consequence,the theoretical derivation of electromagnetic is simplified.The signal in tracking and locating system can't transfer great information because of its extremely low frequency,therefore,the location of the smartball can only be determined through the change of electromagnetic signal strength.A smartball tracking model has been established through researching the motion feature of the smartball in the pipeline in this paper,and then the distribution of electromagnetic fields of the signal transmitter inner the smartball has been derived.On above,a practical application tracking method for smartball and a approach for precise positioning of the leak point have been proposed.And then the tracking and locating system has been established including transmitting system and receiving system of the extremely low frequency electromagnetic signal.Finally,the test experiments in experimental pipe under the condition of the laboratory,in the 130 m water circulating pipe of Xuzhou and in buried 77 km product oil pipeline of Guangzhou have been taken successfully.And also,the results prove that,in the practical application,the scheme of tracking and locating the smartball is feasible,the smartball tracking module theory,presented in this paper,is correct and the tracking method is effective.