Desenvolvimento de técnicas de detecção de incrustação utilizando métodos não invasivos.

Abstract

This project presents techniques for fouling detection in ducts using no-invasive methods. Fouling is a problem which occurs in the chemical, petroleum, food and pharmaceutical industries. This process consists of the accumulation of heavy organic materials and other dissolved solids or in suspension in the fluid transport system. The first technique is based on parameter estimation (with the model of Gaussian pulses) of a system that uses guided waves for fouling detection in pipes. With the used model, the modifications of the parameters are analyzed, when the fouling is present in the monitored pipes. The second technique is based on Wavelet transform, which is a technique of signal analysis via linear combination of elementary functions. While Fourier transform uses a series of complex exponential with different frequencies, the Wavelet transform uses functions that are assigned and moving versions of a function model known as Wavelet mother. With Wavelets the signal energy distribution can be analyzed with the change of the time in different frequency band. Thus, the Wavelet transform is used to analyze ultrasonic signal for fouling detection in pipelines. The energies of the Wavelet coefficients of the ultrasonic signal are determined and the modifications in these energies were observed, when the fouling is present in the pipes. The third technique is based on analysis of vibrations, with the use of a hammer impact. The vibrations are detected by an accelerometer or microphone, allowing the normalization of the measured vibration response for to find the signal response function. Tests with hammer impact have been used in many areas of the engineering for analysis of frequency response function (FRF) due the convenience and simplicity of the experiments, as well as the validity of the analysis procedures. Tests with the hammer impact were used to detect fouling in pipes. With the development of the techniques of fouling detection, it is desired to: reduce the problems caused by fouling; avoid the loss of the operational capacity of the fluid transport systems; increase the safety, optimize the work hand for installation and speed in the obtaining of the information on the fouling process, aiding in the maintenance of the pipes.