Study On Mechanism Of Ultrasonic Anti-scaling And Application In Heat Exchanger

Fouling of heat exchangers is a tricky problem for the production of enterprises. As a new kind of anti-scaling technology, Ultrasonic technology has many advantages that other traditional antifouling methods don’t have. This dissertation simulates two main principles for ultrasonic angle with finite element simulation and is helpful to promote this technology as well as the guidance of equipment installation and selection.Ultrasonic cavitation is one of the important principles of ultrasonic anti-scale technology. By using user defined function (UDF) in FLUENT, pressure fluctuation of vibration boundary is realized. The vapor volume fraction and pressure changing with time under different conditions in the flow field are simulated.The structural response under the action of high frequency vibration transducers which on the shell and tube box is simulated based on ANSYS/LS-DYNA display dynamic analysis. The distribution of shear stress between the scale and the inner wall of the heat exchanger is analyzed. The circumferential shear stress and axial shear stress play a major role in the process of cleaning scale.Under the action of continuous high frequency vibration, for the fatigue failure that may happen at the location where the transducers connected with the outer wall of the heat exchanger, linearization of stress is used drawing on the idea of stress assessment of pressure vessel. Fatigue life analysis is performed according to the stress change amplitude, Sa, and the material S-N curve in these locations.A new evaluation method of fouling monitoring and anti-scaling effect is introduced. According to parameters of one heat exchanger measured during the process of running, the feasibility of this method is verified...