Research On Bag Filter Leak Detection And Location Based On Phase-sensitivity Optical Time Domain Reflectometry

Bag-type dust remover has always been an indispensable dedusting equipment in the field of flue gas purification.It is of great significance to dust filtration.However,once the bag-type dust remover malfunction,it will seriously pollute the air environment if dust smoke is discharged into the atmosphere without reaching the discharge standard.The highest incidence of dust collector failure is the damage of the filter bag.This paper is mainly intended to solve the problem of detection and positioning of broken bags in bag-type dust remover in the cement industry.Based on the analysis of the existing leak detection and position technology of bag-type dust remover,this paper innovatively proposes a leak detection and location method based on distributed optical fiber vibration sensing.Due to its high sensitivity,the fiber-optic vibration sensing system can detect the micro-vibration signal generated by the dust airflow after the bag is damaged.The specific broken bag can be found by calculating the distance of the disturbance signal point from the starting point of the fiber.So the broken bag can be replaced timely,in order to ensure the normal operation of the bag-type dust remover.The content and major innovations of this paper are as follows:(1)Based on the analysis of Rayleigh scattering principle in optical fiber,the basic structure of(p-OTDR system is elaborated in detail.Based on theoretical derivation and software simulation,the model and parameters of each component in the system are determine.Combined with the requirements of bag detection and positioning technology,a φ-OTDR prototype was built.(2)An imitation precipitator simulation platform was set up in the laboratory to determine the relevant performance parameters of the φ-OTDR system.The test results can be obtained:the maximum SNR of the system is 10dB,the actual spatial resolution is 23.7m and position accuracy is 5.37m.Combined with the Fourier transform algorithm,it is verified that the system can respond to dust airflow disturbance signal at low-frequency.The result proved that it is feasible to distinguish the signal of broken bags based on the φ-OTDR system.(3)Apply the system of this paper to field trial.In combination with the actual structure of the baghouse dust collector,a suspended optical fiber laying method was selected.Support Vector Machine(SVM)algorithm is applied to distinguish the abnormal bag from the normal one.The average correct recognition rate is tested to be 97.8%.The combination method of φ-OTDRtogether with SVM is capable of detecting and locating bag filters leak effectively.