Increase heat exchanger run-length by reducing fouling factor
INDUSTRY TERMS | 3 min read
Fouling mitigation is the practice of leveraging technologies or operational methods to reduce the overall fouling factor in a refinery operating unit.
A fouling mitigation method can have one or several objectives:
- Increase turbulent flow to mitigate tube-wall adhesion;
- Reduce frictional resistance to flow (average) for the run duration;
- Remove insoluble particles from the process through electrolysis separation or filtration screens; or
- To inhibit adherence of insoluble particles or the inception of crystalline formation through continuous microscopic agitation or cavitation.
Two approaches to fouling mitigation
Fouling mitigation can be operational or technological in nature.
An example of operational fouling mitigation is online spalling, which is the systematic use of high-velocity steam for the purpose of removing fouling deposits.
Technology-based fouling mitigation take the form of of chemical additives, modular filtration systems, tube insertions, or online ultrasonic cleaning.
Increase heat train run-length with Online Ultrasonic Cleaning
Process Control Room, credit: Winsted
Operational fouling mitigation
Operational fouling mitigation methods are deployed in every processing facility worldwide – it is one of the tenants of operational excellence.
Simply employing highly-trained operators can increase run-length in critical process assemblies without incurring the project costs associated with implementing new technologies.
If our target is to maximize yield while avoiding early shutdown, various operational methods are effective at meeting these short and medium-term processing targets.
However, often operational fouling mitigation methods are not enough. They act as a bandage – inevitably, your equipment must come down for cleaning.
Additionally, improving run-length with operational changes can often be a battle of trade-offs. For instance, if a heat exchanger tube begins to leak, a skilled process operations team asks “which side should we force the leak to enter to minimize the damage until the leak can be repaired?” They can trial and error temperature changes until the pressure difference between the feed and intermediate sides allows for the leak to be restrained to whichever side of the exchanger is less disruptive.
Ultrasonic fouling mitigation technology, credit: Orange Ultrasonics
Fouling mitigation technologies
Fouling mitigation technologies can allow equipment to be sent for cleaning with less overall fouling containment, thereby making them easier and/or faster to clean, or can reduce the frequency of cleaning outages altogether.
Ultrasonic Fouling Mitigation
Ultrasonic online cleaning technology allows for heat exchangers, hoppers and sieves to continue in full operation as cleaning takes place. This allows for greater heat transfer, energy recovery, product throughput, and run-length.
This advantage is an example of Clean-in-Process, and allows producers to take advantage of the competition’s outages by reducing the frequency of their own.