Determinação da espessura da camada de óxido de ferro em tubos de radiant shield de caldeira aquatubular através de processamento de sinais de ultrassom e uso de classificadores

Abstract

Water boilers are equipment of great importance for the industrial park, making the industrial process economically viable. However, they are equipment that present different failure modes, highlighting the failures in the thermal exchange tubes caused by the growth of magnetite present in the internal part of the tubes. Currently, magnetite measurement techniques can be carried out through tests in laboratories (destructive method) or through ultrasound tests with high frequencies (≥20 MHz). In this case, the objective of this work was to develop a method of greater practical applicability for measuring magnetite for thickness 0 µm, 100 µm and 200 µm using a 15 MHz transducer, signal processing and classification techniques, aiming to identify the magnetite thickness classes present in the samples. For this purpose, samples of tubes taken from a water boiler that had a history of failures due to overheating caused by the excessive thickness of the magnetite were used. Subsequently, the ultrasonic signals collected from the samples formed a database, which were treated using mathematical methods and static techniques, then classifying algorithms were used, the classifiers that showed the best performance were selected and finally tests were carried out to validate the method. Test results indicated satisfactory performance in signal classification and testing, showing it to be a promising method for determining magnetite thickness.