The fundamentals of pipeline cleaning with acoustic cavitation

Abstract

This thesis undertakes the fundamentals of a new method for in-situ cleaning of industrial pipe fouling, which shows promising results on a hard commonly occurring fouling in process environment: Calcite. The presence of fouling causes a substantial increase in plant operation costs for a number of reasons, including efficiency reduction, and potentially causes contamination of products. The feasibility of cleaning Calcite fouling from industrial pipework using acoustic cavitation without having to dismantle the pipe network has been explained. For this, the existing theories of acoustic cavitation are related with the out-of-the-plane displacements occurring on the wall of sample pipes induced to vibration to analyse the cleaning process with acoustic cavitation. For the cavitation generation a modification of commercial high power transducers (HPT) is undertaken. The displacements of these HPT are analysed and compared with the displacements established in the theory required to produce transient cavitation. The cavitation produced by the modified HPT is measured with acoustic emission to improve the explanation of the phenomena responsible of the cleaning. Finally, sample pipes are cleaned with ultrasonic waves guided by the pipe wall while measuring the displacement of their outside wall using a 3D Scanning Vibrometer. The most effective cleaning occurs in the vicinity of antinodes and complete cleaning is only achieved when transient cavitation is generated.