Monte Carlo Study of Online Cleaning Cycles of Hydrogenerator Heat Exchangers

Abstract

Related to an innovative cleaning device for cleaning hydrogenerator heat exchangers that does not require the interruption of generation (turning off the turbines), this article discusses two alternative schemes to estimate the minimum number of cleaning cycles required to ensure that all tubes of the heat exchanger will be visited at least once by the cleaning artifacts used by the conceived online cleaning system. The technique makes use of abrasive sponge balls transported by the cold working fluid of the exchanger to remove scale that accumulates inside the exchanger tubes during its operation. The main purpose of this study is to guide the hydrogenerator field operator in setting up the automation system of the exchanger cleaning system. In a first attempt, a negative binomial probability distribution function was investigated to estimate the number of tries needed to obtain a number of success events, with equal probability of success, after running a number of Bernoulli's experiments, where the last is considered the success case. Getting closer to the physical reality of the problem studied, a Monte Carlo method simulation, making use of a high number of repetitions (10 x 10⁶), appeared to be a consistent mathematical formulation to anticipate the smallest number of cleaning cycles meeting the posed assumption.

Acknowledgements

Thanks are due to the electricity utility Light Energia S/A and to the Regulatory body of the Brazilian electrical sector, for the financial support via the R&D Project Light-Aneel 5161-010/2016. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES), Finance Code 001.

Disclosure statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

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Notes on contributors

Jefferson Luiz Rangel Rios

Jefferson Luiz Rangel Rios graduated in Mechanical Engineering from the Pontifical Catholic University of Rio de Janeiro where he recently obtained the title of Master in Metrology for Quality and Innovation (January 2021). CEO of the SEPIEM enterprise (Research and Innovation Services in Engineering and Metrology).

Maurício Nogueira Frota

Maurício Nogueira Frota has a PhD in Mechanical Engineering (Stanford University, 1982). In the past, he held the positions of Director of Scientific and Industrial Metrology of the National Institute of Metrology of Brazil, President of the Inter-American Metrology System of the Americas (SIM) and Vice President of the International Measurement Confederation (IMEKO). Currently, he is Emeritus Professor of the Postgraduate Metrology Program of the Pontifical Catholic University of Rio de Janeiro, Brazil.

José Daniel Hernández-Vásquez

José Daniel Hernández Vásquez holds a Master's degree in Metrology and a Doctoral Degree in Mechanical Engineering from the Pontifical Catholic University of Rio de Janeiro Brazil. He is currently the Research Coordinator at Facultad de Ingeniería Mecánica, Electrónica y Biomédica (FIMEB) of the Mechanical Engineering Program at the Universidad Antonio Nariño, Colombia.

Carlos Roberto Hall Barbosa

Carlos Roberto Hall Barbosa holds a Doctoral Degree in Electrical Engineering from the Pontifical Catholic University of Rio de Janeiro (PUC-Rio), Brazil, where he serves as Coordinator of the Postgraduate Metrology Program. From 2000 to 2004, he was a Researcher with the Applied Computational Intelligence (ICA) Laboratory at PUC-Rio. Since 2004, he has been a Professor with the Postgraduate Program in Metrology at PUC-Rio. His research interests include metrology, high voltage tests, computational intelligence, signal processing, biomagnetism, and nondestructive evaluation.