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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Pool Boiling of Hydrocarbon Mixture in Kettle-Reboiler with Low-Finned Tubes

Get access (open in a dialog) DOI: 10.1615/IHTC15.hte.009864
pages 4097-4110

Sinopsis

In this paper, pool boiling of n-pentane and a 80/20 mole % mixture of n-pentane/iso-octane on low-finned tubes was investigated to check the suitability of the tubes for industrial applications with hydrocarbon mixtures. The tests were performed at the Linde Engineering Division in a kettle reboiler commonly used in the process industry and integrated in a 300 kW pilot plant station. The reboiler bundle had 82 integral low-finned tubes Gewa-K30 (1181.1 fins/m, 18.94 mm envelope diameter) in carbon steel. Heat transfer experiments were carried out in a flux range related to the envelope area of 4 to 30 kW/m² and at saturation pressures of 1.4 to 3.3 bar, corresponding to boiling temperatures of 40 to 110 °C. The investigation focused on both composition and temperature shift occurring in kettle reboiler due to the separation between the vapour and the liquid phase. The objective was to determine the impact of this enrichment on the thermal heat exchanger performance. The local shell-side temperatures were measured with help of a fiber optic technique and the bulk composition was measured within the bundle with chromatography. The results indicated a rise of boiling temperature along the tube length from 2.5 to 10 °C, corresponding to a decrease of the more volatile composition from 4 to 14 mole %. As a consequence, the mean heat transfer coefficients were 25 to 45 % lower for the mixture than for n-pentane. The comparison of the performance of low-finned tubes in the kettle reboiler with single tube data obtained on the same tube and under the same operating conditions results in bundle factors ranging between 1.0 and 1.6 for pure n-pentane and 1.25 to 1.45 for the n-pentane/iso-octane mixture.