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Proceedings of an International Conference on Mitigation of Heat Exchanger Fouling and Its Economic and Environmental Implications

1-56700-172-6 (Print)

Statistical Characterization of Time Between Cleaning of Thermosyphon Reboilers in Oil Industry

Anwar K. Sheikh
Department of Mechanical Engineering King Fahd University of Petroleum & Minerals Dhahran 31261, SAUDI ARABIA

Jamil J. Al-Bagawi
Saudi Aramco Dhahran Saudi Arabia


In this paper, the impact of fouling on the operational reliability of a stabilizer column's reboiler (heat exchanger) is studied. These stabilizer columns are not reactors. The objective of such a stabilizer plant is to remove H2S from the sour crude by heating it and passing it over a series of trays, the resulting sweetened crude, is then delivered to the storage tanks, refineries or shipments. The time between cleaning is defined as the time required to reach a critical level of fouling after which the reboiler cannot perform at its intended heat capacity or desired heat duty. The time between cleaning of these heat exchangers (thermosyphon reboilers) is characterized using statistical distributions. Various probability models are fitted to the time between cleaning data. Based on the coefficient of determination, the best statistical model is identified which can be used in developing an optimal maintenance strategy for such heat exchangers. Other operational failure statistics, such as MTTF, standard deviation and median time to failure are also reported. In addition it is pointed out how the parameters of selected model can be used to simulate the underlying average or median fouling growth pattern of these heat exchangers. Such simulated fouling growth curves can provide the clue to adjust the operational parameters such as velocity at a level, which can enhance the average time between these operational failures.