Diagnosis of intermittent failures is relevant for productive processes which sustain a high level of maintenance caused by failures. Systems including electrical contacts suffer a considerable amount of intermittent failures which are usually not diagnosed. A characterization of the failure dynamics may save unnecessary repairs, and enable a better planning component substitution. This paper presents a new concept in failure diagnosis, the modeling of intermittent failure dynamics. It develops two methodologies for modeling intermittent failure dynamics, and generating information for maintenance scheduling.

Naphtha is an important distillation product of crude oil, and is used as a raw material for first-generation products such as ethylene, propylene, gasoline, xylene (BTX), and others. However, due to the different sources of crude oil, differences in naphtha composition impact the quality of conversion processes. Parameters such as pressure, charge flow, and temperature need to be adjusted for conversion efficiency. This work aims to compare naphtha samples from different origins, through the analysis of distillation curve (ASTM D86), density (ASTM D4052), total sulfur (ASTM D4294), and n-paraffins, iso-paraffins, olefins, naphthene, and aromatics (PIONA, ASTM D5134). Among these parameters evaluated in naphtha, the ones that showed the greatest correlation with the type of oil and its origin was the amount of total sulfur, number of aromatics, and paraffins. The three imported evaluated naphtha presented values greater than 200 mg/kg of total sulfur, aromatics above 9%w, and paraffins (P + I) below 76%w, while the national naphtha presented sulfur contents of at most 141 mg/kg, aromatics below 7%w, and paraffins (P + I) above 78%w. Finally, the study of this type of hydrocarbon enables the understanding of the needs of Latin American refineries and the world in relation to its treatment. National petrochemical companies have more difficulty in processing this product, causing an increase in naphtha importation by 108.51% from 2020/2021 in Brazil. Given this scenario, the Brazilian government should invest more in its petrochemical plants to reduce these imports, which, in the long term, would have a positive impact on the quality and value of naphtha byproducts.