Research On Fouling Removing In Pipelines Based On Ultrasonic Guided Waves

The technique of pipeline descaling is of great significance for the safety operation of pipelines,such as petroleum,chemical,water supply and food industry.The fouling process is relatively slow,and the cause of fouling are complex and various.If fouling cannot be treated timely,it will cause decrease of flow velocity and even blockage or explosion risk,which is a great danger to industrial safety.Compared with traditional methods such as mechanical and chemical method,ultrasonic guided waves can achieve descaling of a relatively large area in pipelines.Moreover,it can remove fouling on-line without interfering the normal production,and has advantages of low running cost,little environmental pollution and high working efficiency.In this paper,the fouling removing technique based on ultrasonic guided waves has been studied theoretically and experimentally.A finite element simulation software is used to obtain the acoustic pressure distribution characteristics of the liquid surface of the pipeline under the ultrasonic guided wave,then the region of pipeline inner wall which can stimulate the cavitation effetely is obtained.In addition,a transverse shear stress model of fouling pipeline was built by finite element simulation software,and the shear stress between inner wall and scaling layer was analyzed.Based on the simulation results,the pipeline scale removal system is designed and verified.The ultrasonic guided wave transducer for descaling is designed and calibrated in the paper.The descaling experiment was carried out by using the transducer,then carry on the SEM and EDS analysis.The experimental results show that the cavitation effect and shear stress produced by the ultrasonic guided wave can effectively remove calcium carbonate fouling on the pipeline wall,and there is no obvious damage on the surface of the pipe after the descaling.So,it is feasible to remove the fouling inside the pipe by ultrasonic guided wave.With the ultrasonic guided wave technique,the pipeline descaling engineering can be improved in the following two aspects:in the first,ultrasonic guided wave can propagate far away with small attenuation,and it is not sensitive to the coating inside and outside of the pipeline wall.So,the single point operation of traditional scale removal is avoided.In the other,ultrasonic guided waves has little influence with the pipeline filled with liquid or gas.This characteristic can be used for fouling removing operations without downtime or modification,and the cost is greatly reduced.