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Morphological study of external fouling on air cooled fin tube heat exchangers in oil & gas processing plant


In the UAE the majority of oil & gas processing plants are located in the dessert where water accessibility is limited thus they tend to use fin-fan type of heat exchangers for cooling and/or heating. With such type heat exchangers in such an environment external fouling becomes an unavoidable problem. And when humidity and high process temperatures are added the matter gets worse where dusty/sticky particulate start to form on the external side of the heat exchangers which drastically reduces the thermal performance and thus increasing the power consumption. Frequent cleaning/maintenance is not quite effective and may require shut down which is costly. In order to identify possible methods to control or eliminate external fouling, it is important to know the exact composition and morphology of such foulant materials. The current study presents morphological characterization of selected fouling samples from eight different heat exchangers of a gas processing plant that were examined using different methods such as: scanning electron microscope (SEM) integrated with energy dispersion x-ray spectroscopy (EDS), X-ray diffraction (XRD) and Laser Flash Analysis (LFA) were conducted to know foulant's surface topography and composition, crystal structure and thermal diffusivity. The tests revealed that most foulant composed of Silica (Si), Calcium (Ca), Carbon (C) and Aluminum (Al) with traces of Magnesium (Mg), Sodium (Na), Iron (Fe), Chlorine (Cl) and Sulfur (S). The samples had averages of the following phases: 58 % CaCO3 (Calcite), 17 % SiO2 (Quartz), 16 % Al2O3 and 9 % others.