»
Fouling
Understanding fouling in heat exchangers – Part 2
Heat exchanger shell and tube at offshore oil and gas central facility .
In part one of this article ( published in Heat Exchanger World October issue ), we discussed the types , causes , effects , cost , and mitigation strategies for fouling in heat exchangers . Now we will explore the detection methods to assist in fouling intervention .
By Omari Hussein Sabuni , Mechanical Engineer - Kinyerezi Power Plant
Detecting fouling in its early stages is crucial for timely intervention and effective mitigation . There are various methods for detecting fouling in heat exchangers , enabling proactive maintenance and optimal performance .
Thermal analysis Thermal analysis techniques provide valuable insights into the presence and severity of fouling in heat exchangers . The following methods are commonly employed : Temperature difference monitoring : By measuring the temperature difference between the hot and cold fluid sides of the heat exchanger , any deviations from the expected values can indicate the presence of fouling . An increasing temperature difference suggests reduced heat transfer efficiency , signaling the need for further investigation . Heat transfer coefficient calculations : Calculating the heat transfer coefficient using heat exchanger performance data can help identify changes in heat transfer efficiency caused by fouling . A decline in the heat transfer coefficient over time indicates the presence of fouling and the need for remedial action .
Infrared thermography : Infrared thermography involves using thermal imaging cameras to detect temperature variations across heat exchanger surfaces . Hotspots or uneven temperature distribution can indicate areas of fouling or blockage , enabling targeted maintenance interventions .
Pressure drop monitoring Monitoring the pressure drop across the heat exchanger can serve as an effective indicator of fouling . Fouling deposits restrict fluid flow , resulting in increased pressure drop . The following methods aid in pressure drop analysis : Differential pressure measurement : By measuring the pressure difference between the inlet and outlet of the heat exchanger , any substantial increase in pressure drop indicates the presence of fouling . Regular monitoring of pressure differentials allows for timely fouling detection and appropriate maintenance actions . Flow metre analysis : Analyzing flow rates using flow meters installed in the heat exchanger system can help identify changes in fluid flow caused by fouling . Reduced flow rates or fluctuations may suggest fouling issues , prompting further investigation .
Visual inspection Visual inspection remains a fundamental method for detecting fouling in heat exchangers . Direct observation of heat exchanger surfaces can reveal visible signs of fouling , such as deposits , scaling , or corrosion . Key visual inspection approaches include : Borescopic examination : Borescopes , equipped with cameras or fiber optics , allow for visual inspection of
22 Heat Exchanger World February 2024 www . heat-exchanger-world . com