Study On Uitrasonic Anticorrosion And Scale-retardation Technology Of Spiral Tube Heat Exchange

Because of the high heat transfer efficiency and compact structure,the spiral wound tube heat exchanger is widely used now.The corrosion resistance of this heat exchanger is poor and the operation cycle is longer,the heat transfer tube in the shell is generally selected spiral wound light pipe in engineering applications,so the fluid impurities and other dirt easy to deposit and block affecting the efficiency of equipment.The the anti-corrosion and scale-retardation technology for spiral wound tube heat exchanger were studied based on ultrasonic technology in this paper.Ni-P alloy was deposited on the surface of the heat exchanger or the heat transfer tubes(The heat transfer tube material is generally made of 316 L stainless steel)by ultrasonic electroless plating which greatly improve the corrosion resistance.At the same time,the unique spiral die design and ultrasonic cleaning device can make the heat exchanger online self-cleaning.The main contents included:Ni-P alloy was deposited on the surface of 316 L stainless steel by ultrasonic electroless plating and the optimum formula was selected by orthogonal experiment,methods include SEM and EDS were used to represent the surface morphology and composition of the 316 L stainless steel substrate,Ni-P coating by electroless plating and Ni-P coating by ultrasonic electroless plating.Meanwhile,the electrochemical behavior of the coatings was also tested in the HCl to analyze the corrosion resistance of the coatings.The results indicated that the coating obtained by ultrasonic electroless plating gained a higher hardness,better surface quality and corrosion resistance than that of ordinary electroless plating.The sound field directivity range and sound intensity of different frequency and different transducer radius are simulated by MATLAB.Simulation shows: it can achieve the best scale effect at a frequency of 28 kHz,the transducer radius of 45 mm,which also take into account the sound field directivity and sound intensity.The simulation results provide a theoretical basis for the transducer selection.Ultrasonic scale spiral heat exchanger was designed including the heat exchanger and the ultrasonic scale device.The installation forms of ultrasonic scale device is very important,including external and built-in two forms.The external structure is simple,but there is ultrasonic attenuation;the built-in make full use of the core space of heat exchanger and solve the problem of ultrasonic attenuation,and the cleaning effect is better.In addition,the sound field verification experiment of the ultrasonic scale inhibitor was done,which use the ultrasonic staining method.The results show that the ultrasound existed in the shell side of the heat exchanger,which can make the heat exchanger to achieve self-cleaning.