The objective of this paper is to evaluate from the output surface the damage of the catalytic tubes of the columns of the reformer furnaces in order to predict its remaining life. Catalytic tubes are the most critical components in reformer furnaces. Reformer furnaces are widely used in the petrochemical industry to produce hydrogen from hydrocarbons. It is in the radiant tubes containing a catalyst that the hydrogen production takes place, as a result of endothermic reactions between hydrocarbons (mostly methane) and water vapor. These reactions proceed at a temperature range between 800 and 900 deg C and the working pressure in a reformer furnace is between 2 and 5 MPa. These are severe working conditions that cause structural damage in the tubes. It is necessary to develop methods for the inspection of tube degradation and for a realistic prediction of its residual life.

Some analytical methods have been developed to estimate reformer columns service life or the time to failure, as the assessment of damage and advance planning of column replacement should be made to ensure that failures or unplanned shutdowns are avoided. However, direct methods to evaluate the probable extent of damage and remaining life in a particular furnace are always much more preferable. Nowadays, direct tests are performed destructively by examining metallographically the microstrutural changes and creep damage on a series of ring samples cut along the length of single tube removed from the reformer furnace. The objective of this project is to project and implement an in-situ measurement system to inspect through a nondestructive testing (NDT) technique, based on eddy currents, reformer tubes damages to infer about its remaining life.

The eddy current method is based on the excitation of the material with a time variable magnetic field. In this way, the electromotive force developed inside the material will give rise to electric eddy currents. These currents are related to the conductivity distribution of the body and exhibit certain patterns that can be predicted by measuring the total magnetic field in the vicinity of the material. In the presence of defects, such as cracks due material fatigue, the eddy currents deviate from its normal geometrical configuration, and this perturbation on the eddy currents can be sensed by magnetic sensors placed close to them. This technique enables not only the detection of cracks due to material fatigue but also the appearance of intermediate stages that are correlated with the micro-structural changes that occur during service.

This project deals with a challenging problem very important for the petrochemical industry. It is to be developed in partnership with colleagues from the Laboratório de Ensaios Não Destrutivos, Corrosão e Soldadura from Universidade Federal do Rio de Janeiro. They shall provide us characterized samples taken from reformer furnace tubes with different damages and degradation. The work included within this proposal will complement their work on the failure analysis and remaining life assessment of the tubes based on the microstructural observations they perform using different techniques like light microscopy, scanning electron microscopy, transmission electron microscopy and diffraction and carried out within a research project supported by Petrobras. It is our belief that the success of this work in partnership would enable our participation in future projects now that the agreement with Instituto de Petróleo e Gás and Petrobrás is underway.

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