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In refineries and petrochemical plants, exchanger fouling is a persistent challenge that can severely reduce heat transfer efficiency and increase pressure drop. These effects often lead to rate limitations on the unit, the need for unplanned mechanical cleaning, or in severe cases, full unit shutdowns. When scheduled turnarounds are weeks or months away, online cleaning has become a valuable strategy to mitigate fouling and sustain operation without interrupting production.
What is online cleaning?
Online exchanger cleaning refers to the application of chemical cleaning solutions to process equipment while it remains in operation. This method minimizes production downtime and avoids the safety risks associated with shutdowns by addressing fouling and contamination under live process conditions. Specialized chemistries are formulated to dissolve asphaltenic or paraffinic deposits and restore equipment efficiency without interrupting throughput.
ZymeFlow has developed a suite of proprietary chemical solutions and injection strategies designed specifically for online cleaning. These formulations are engineered to work within the thermal, pressure and metallurgical limits of operating equipment, ensuring system integrity while improving performance. Each solution is tailored to the plant’s process configuration, process streams and specific type of fouling.
Operational advantages of online cleaning
Online cleaning: Keeping equipment running until turnaround
Facilities that implement online cleaning as part of their exchanger maintenance strategy report measurable gains in performance and reliability. Key benefits include:
- Sustained throughput: Fouling is mitigated during operation, helping maintain heat transfer rates and avoid unit rate restrictions.
- Reduced pressure drop: Online cleaning helps relieve excessive back pressure across exchanger bundles, improving flow dynamics.
- Deferred mechanical cleaning: Allows units to defer intrusive maintenance until a scheduled turnaround, reducing labor and cost.
- Improved safety margins: While not a replacement for full decontamination, online cleaning can lower risk by minimizing fouling-related process upsets.
Online cleaning: Keeping equipment running until turnaround
By targeting exchanger fouling in situ, online cleaning preserves system performance without compromising production continuity.
Common applications
Online cleaning has proven especially effective in heat transfer equipment prone to heavy fouling. Typical applications include:
- Vacuum tower bottoms exchangers: Mitigation of asphaltic fouling that restricts flow and thermal performance.
- Coke preheat train exchangers: Mitigation of asphaltic fouling that increased differential pressure and limits rates.
- Crude preheat train exchangers: Removal of paraffinic fouling leading to increased fuel gas usage and reduced rates.
- Overhead condensers and reflux systems: Restoration of heat exchange efficiency and reduced condensing pressure.
- Visbreaker and hydrotreater feed exchangers: Cleaning of polymer-laden fouling that leads to reduced heat transfer and rate limitations.
One example includes an online clean of a fouled Diesel Hydrotreater feed exchanger, where ZymeFlow’s customized chemistry restored flow and reduced pressure drop — avoiding shutdown and enabling continued operation until the next turnaround.
Strategic role in turnaround optimization
While online cleaning is not a replacement for mechanical or turnaround-based cleaning, it plays a vital role in reducing the severity of fouling ahead of shutdowns. This leads to:
- Shorter cleaning windows during turnarounds
- Safer mechanical entry and hydroblasting conditions
- Improved planning confidence through validated decontamination data
When used strategically, online cleaning helps operators bridge the gap between turnarounds while extending asset reliability.
Implementation best practices
Successful exchanger online cleaning programs depend on engineering alignment, operational readiness and chemical expertise. Recommended best practices include:
- Fouling diagnostics: Analyze exchanger thermal performance trends and fouling patterns to define cleaning goals.
- Chemical compatibility reviews: Confirm process material compatibility with cleaning agents.
- Chemical dosage rates: Evaluate carrier solution along with process parameters such as temperature and flow rate to ensure effective and efficient cleaning performance.
- Controlled injection and flow design: Optimize flow paths and injection points to ensure uniform chemical contact.
- Performance monitoring: Track key indicators such as pressure drop, overall heat transfer coefficient (U-value), and effluent composition to evaluate cleaning effectiveness and adjust chemical dosing for future optimization.
Post-clean documentation: Capture data for future reliability programs and turnaround scope planning.
Enabling long-term reliability
As margin pressures grow and reliability standards rise, unplanned exchanger-related outages are increasingly unacceptable. Online cleaning gives plant teams the flexibility to manage exchanger fouling without interrupting operations — supporting higher uptime, reduced emissions and smarter maintenance planning.
To learn how ZymeFlow can design an exchanger-focused online cleaning program tailored to your plant, contact the ZymeFlow team. Their proven approach — rooted in laboratory testing, field validation and more than three decades of industry experience — offers a clear look at how ZymeFlow customizes online cleaning solutions for maximum efficiency and reliability.
For more information, visit zymeflow.com.
