Research On Antifouling Of Underwater Production System Based On Ultrasonic Cavitation

As the significant form of the exploitation of marine resources,underwater production system has many several unique advantages.However,the production system set beneath the water surface statically for a long time could easily lead to a large number of fouling organisms,which will result in the reduction of the diameter of the sea pipe,the prevention and reduction of the flow of seawater.Furthermore,it will also block the valve,increase the carrying load of the sea pump and reduce the cooling efficiency of the heat exchanger.As the consequence,the production equipment will shut down due to excessive load and also the corrosion perforation of attachment base,resulting in local corrosion,resulting in potential safety hazards and immeasurable economic losses.Therefore,the biological prevention and control of marine fouling in underwater production system is of great significance from the perspective of economy and security.At present,the main antifouling at home and abroad is painting antifouling paint with limited service life.Therefore,the development of new antifouling schemes plays an important role in related areas.Based on the actual demand of anti-fouling of CNOOC oil-water subsea production system,the study explores the anti fouling scheme based on ultrasonic cavitation.The scheme proposed by this research owned the advantages of adjustable power,high economy,high reliability and the inefficiency of normal operation of the production system.The major work are as follows:Firstly,after the literature review and data investigation,the advantages and disadvantages of different anti-fouling schemes were compared.In addition,the applicability of ultrasonic anti-fouling for underwater production system was also clarified,and the research status of ultrasonic cavitation field and sound field was investigated and explored,which provided robust reference for the research of ultrasonic cavitation field and sound field.Secondly,the sound field of ultrasonic transducer was numerically simulated.To be specific,the sound field characteristics of sandwich piezoelectric transducer in water were simulated,together with the simulation of effects of different packaging structures on the sound field of transducer.In addition,the sound field characteristics of different packaging structures were obtained with the the sound pressure level distribution images of simulation results.Thirdly,the hydrophone was employed to measure the ultrasonic sound field.To be specific,different packaging styles were processed and assembled,and the sound field parameters was measured in the real sea.The sound field parameters of each point in the transducer sound field were recorded and plotted,in order to obtain the actual sound field distribution under different packaging structures.Compared with the simulation results,the consistency between the actual results and the simulated one provided the evidence of the the correctness of the simulation and the distribution law of the sound field was also found out.Finally,ultrasonic antifouling test in the real sea was conducted.The test of anti-fouling in open environment and caisson environment were designed respectively with the process of equipment such as open sea area support and underwater caisson and the completion of customization and packaging of ultrasonic generator and transducer.What’s more,the real sea test in the peak season of marine biological growth in summer and autumn was carried out by comparing the growth of marine organisms in the anti-fouling sample under ultrasonic action with that in the blank sample,which turned out the effectiveness and reliability of ultrasonic anti-fouling.