Design Of Acoustic Monitoring System For Valve Internal Leakage Based On Wireless Sensor Network

In the field of petrochemical industry,oil pipelines are laid in large numbers,and valves as fluid control devices are also widely used in them.Due to improper operation,wear and corrosion,natural aging and other factors,valve seal failure occurs from time to time.When the valve internal leakage fault occurs,it is usually difficult to detect,resulting in serious consequences,so it is necessary to monitor the sealing state of pressure valve in real time.In this paper,aiming at the valve internal leakage fault,a valve leakage acoustic monitoring system based on wireless sensor network is designed.Among them,the monitoring instrument is installed on the pipeline near the downstream of the detected valve in a non-destructive adsorption way,and the valve internal leakage is sensed by an acoustic sensor attached to the pipe wall.The output signal of the sensor is sampled after conditioning circuit conditioning.In the monitoring process,the data collection and processing are carried out by the embedded microprocessor inside the instrument.After the local real-time diagnosis,the diagnosis results are sent directly to the monitoring server by wireless communication.When the server receives the internal leak alarm information sent by a sensing node,it will get the serial number(position)of the valve where the internal leak fault occurs and the characteristic vector corresponding to the current abnormal signal.Compared with the previous monitoring mode of real-time upload sampling data and use the server to diagnose fault,this monitoring mode of direct upload diagnosis results can not only greatly reduce the amount of data transmission between the monitoring instrument and the server,but also save the calculation resources of the server,so that the server can link more monitoring instruments,which is convenient for the server to receive and display the monitoring results of multiple valves.The instrument adopts wireless sensor network for communication,which will make its installation in the industrial site more convenient.In view of the shortcomings of the existing valve leakage acoustic monitoring methods,which only focus on the transient characteristics of abnormal signals and have a high false alarm rate(about 3%),In this paper,in order to reduce false positives as the goal,to improve the existing based on abnormal signal transient feature of the feature extraction method,as well as on the continuous feature of abnormal signal are studied,and put forward a method about using the internal leakage signal continuous feature to decrease false alarm.The false alarm rate is decreased,and the alarm accuracy is increased under the premise of not causing the underreporting(certain conditions).In addition,the paper also introduces the instrument design scheme based on the integration of monitoring functions,including the instrument hardware design and embedded program writing.The developed monitoring server program can fit the various functions involved in the monitoring instrument.The consequences in the lab of the test show that the monitoring system designed in this paper can link multiple monitoring instruments in the way of networking and has a high fault detection accuracy.