Morphological characterization of fouling on air cooled fin fan heat exchangers

In today's fast growing world where availability of energy has become a major concern, the cost of performance demands optimum heat exchange performance over extended periods of operational times. Fouling is one major factor that drastically affects heat exchanger performance. Most of the oil & gas processing plants in the Middle East are located in deserts. Due to scarcity of water most of the installed heat exchangers are air-cooled. These heat exchangers are at high risk of low performance due to dusty/sticky particulate fouling. In order to identify possible active/passive methods to control or ideally eliminate particulate fouling, as a first step, it is desirable to know exact morphology of such particulate fouling. This study presents morphological characterization of selected fouling samples from eight different installed fin fan heat exchangers. The scanning electron microscope (SEM) tests are carried out to determine standard characteristics and size of sample foulant powder. Variability in sizes and shapes is found between samples perhaps due to different working temperature ranges of the selected heat exchangers. The semi quantitative sample composition measured by energy dispersion x-ray micro analysis was as following: 26.50% Si, 26.12% Ca, 10.07% C and 9% Al with traces of Fe, Na, Mg, Cl, and some other salts. X-ray diffraction analysis revealed presence of quartz, calcite and alumina with traces of halite and hematite. The diversity of these fouling samples reflects complexity with respect to their potential removal and effects on heat transfer.