Careers Recover Lost Thermal Efficiency and Stabilize Critical DCU Operations
At a major North American refinery, the Delayed Coking Unit (DCU) converts low-value vacuum residue into high-value products, including LPG, naphtha, and LCGO. As one of the few processes capable of upgrading the heaviest fractions of crude, it directly influences refinery margins, where even small efficiency gains translate into significant financial impact.
Across three Terrace-Wall™ DCU heaters, fouling within the convection sections had reduced heat recovery, shifting thermal demand to the radiant section. A pre-project thermal efficiency audit indicated performance had degraded to nearly 50% of design duty.
The objective was to restore efficiency, reduce fuel consumption, and improve reliability without extending turnaround duration or increasing safety risk.
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Selecting the Most Effective Path to Performance Recovery
Previous cleaning attempts, including dry ice and chemical methods, had delivered inconsistent results and limited performance improvement.
The IGS TubeTech™ solution was selected based on several decisive factors:
- Proven ability to deliver full cleaning coverage in complex convection geometries, regardless of fouling type or severity
- Elimination of confined space entry risks through robotic deployment
- Compatibility with tight turnaround schedules
- Feasibility Study, including prior audit estimates showing strong economic benefit potential
This positioned robotic cleaning as a targeted performance reinstatement strategy.
TubeTech™ ROV Convection Section Cleaning System
This was not routine maintenance; it was a targeted performance reinstatement project to recover lost thermal efficiency and stabilise operation in coking-sensitive heaters.
Addressing Cleaning Limitations in Complex Convection Geometries
Convection sections in DCU heaters present a challenging environment, with tight fin spacing, complex geometries, and heavy, uneven fouling. Conventional methods are often limited by access and consistency, leaving residual fouling that continues to restrict heat transfer.
The TubeTech Remotely Operated Vehicle (ROV) system addresses these constraints by delivering controlled, repeatable cleaning across the full tube surface, enabling full-surface coverage and repeatability not achievable with conventional or manual methods.
Deliver Full Coverage without Compromising Turnaround or Safety
IGS deployed its proprietary ROV system to clean the convection section tubes across all three heaters. Each heater consisted of four tube coils, approximately 70 feet / 6.50 square meters in length.
The robotic system enabled:
- 90–95% cleaning coverage of all accessible convection tubes surfaces
- Consistent removal of fouling deposits
- Elimination of confined space entry risks
- Access to confined, high-density tube arrangements that cannot be effectively cleaned using manual methods
The project was completed within 9 shifts and delivered zero safety incidents.
To support long-term maintenance strategy, two access doors per heater were engineered and installed, introducing access where none previously existed, enabling future interventions and reducing downtime.
Translating Cleaning into Measurable Efficiency and Reliability Improvements
By removing fouling, the project restored the heaters’ intended thermal balance, increasing upstream heat recovery and reducing radiant section demand. A post-project evaluation produced the following results:
Overall Performance Impact Summary
Convection Duty Recovery by Heater
Performance improvements were consistent across all three heaters:
Notably, fuel savings were achieved while operating at even higher coil outlet temperatures, demonstrating that performance gains were driven by restored heat transfer rather than changes in operating conditions.
Engineered access door installed to enable efficient, repeatable convection section cleaning
“This project restored the thermal balance of the heaters in a way the operations team could immediately see and sustain. Measurable efficiency gains, improved reliability, and faster future maintenance deliver immediate and lasting operational impact.”
– James Turner, Business Development Manager, IGS
Enabling Faster Repeat Interventions and Expanding Site-Wide Impact
The installation of access doors reduces future cleaning duration and simplifies maintenance planning. The success of this project has already driven further engagement and expansion opportunities:
- Interest in expanded services, including online cleaning and advanced protection solutions
- Ongoing discussions around upcoming outages and additional heater applications
- Recognition of robotic cleaning as a scalable, repeatable maintenance strategy
This project established a scalable approach for improving heater performance across the site
Restored heat transfer delivered convection duty recovery, ~4.0 MMBtu/hr fuel savings, and a measurable improvement in heater reliability.
That’s Asset Vitality.
WATCH: TubeTech Robotic Convection Section Cleaning System
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