Research On Fouling Detection And Removing In Pipelines Based On Ultrasonic Guided Waves

For industries such as petrochemical,pharmaceutical,food and water supply and drainage industries that need pipelines to deliver fluid,the fouling detection and cleaning inside pipelines are of great significance.The fouling may lower the production efficiency and cannot guarantee the product quality and some safety accidents may happen because of pipeline blockage caused by fouling.The operating principle of using the ultrasonic guided waves technique to detect and remove fouling inside pipelines is that ultrasonic guided waves can be transmitted for a long distance inside the pipe walls with relatively low attenuation.Compared to traditional methods of detecting and removing fouling inside pipelines,this method has the following advantages:Firstly,compared to other transmission routes,ultrasonic guided waves can be transmitted inside the pipe walls with less attenuation for decades of meters.When detecting the fouling layer,it can detect the fouling within decades of meters or even over one hundred meters.Therefore,using this method,people don't need to measure the width of pipes to detect the fouling layer one by one,which greatly reduces the labor cost and improve the work efficiency.Secondly,ultrasonic guided waves can be transmitted inside pipes with fluid and coating layer,which makes it possible to detect and remove fouling without interrupting the production,modifying a pipeline and its related equipments and reduces the expenses of removing fouling.In this thesis,fouling detection and removing in pipelines using ultrasonic guided waves is primarily studied.Combined with the principle of detection and cleaning of fouling in pipelines using ultrasonic guided wave,a series of analysis of the reflection signal has been done as below,some conclusions are obtained:1,the ultrasonic guided wave in fouling layer front end after fouling layer,and the pipe end can produce reflection signals.2,The reflection signal from the front end of the fouling layer can be used to locate the fouling in the pipeline.3,the reflection signal from the front end and the back end of the fouling layer can be used to estimate the length of the fouling area.4,There is a certain relationship between the reflection signal intensity in the front and back end of the fouling and the thickness of the fouling layer.By using the ABAQUS finite element software,a simulation model of fouling detection in pipeline based on ultrasonic guided wave has been established.By using GUIGUW,a frequency dispersion curve drawing software,the group velocity dispersion curve of the pipeline model have been plotted and the optimal frequency and mode of the ultrasonic guided wave signal have been obtained.Based on the above analysis results,the finite element simulation of ultrasonic guided wave analyzed,which shows the fouling detection and removing technology inside pipelines is effective,which is based on ultrasonic guided waves,.Finally,based on the simulation detection of the pipeline model with fouling layer is achieved and the simulation results are model,the below work have been done,which contains an experimental system,the experimental pipeline,ultrasonic transducer,guided wave signal excitation,receiving isolation circuit and virtual signal generator.The experimental results show the feasibility of fouling detection in the pipeline using ultrasonic guided waves.