Careers Remove Deep Gas-Side Fouling And Improve Future HRSG Maintainability
At Lodi Energy Center, a 282 MW natural gas-fired combined cycle power plant in California, inspection revealed heavy rust fouling deep within the Nooter HRSG’s finned tube bundles. During a five-day planned outage, IGS used PressureWave+™ cleaning across four HRSG sections, completing 1,584 events and removing debris accumulations up to 25 inches—restoring deep-bundle cleanliness while improving access and efficiency for future outages.
Project Overview
| Plant | Lodi Energy Center |
| Capacity | 282 MW |
| HRSG | Nooter |
| Duration | 5 days |
| Sections Cleaned | 4 |
| PressureWave+ Events | 1,584 |
| Maximum Debris Removed | Up to 25 in. |
Why Deep HRSG Gas-Side Fouling Matters
Gas-side fouling restricts exhaust gas flow through the HRSG, increasing gas turbine backpressure, reducing heat transfer, and limiting available generating capacity. Conventional methods can remove accessible deposits, but fouling located deep within dense finned tube bundles may remain, continuing to impact performance. PressureWave+™ is designed to transmit pressure waves through the tube bundle to dislodge deposits from these difficult-to-reach areas.
HRSG Fouling Removal Without Extending the Planned Outage
Following a detailed inspection, the cleaning strategy was tailored to the fouling conditions identified throughout the HRSG. Inspection confirmed:
- Heavy rust fouling between finned tube bundles
- Significant debris accumulation beneath tube bundles
- Internal baffles requiring modified techniques
- Existing access constraints requiring rigging through roof-mounted Sky Climber ports
To maximize application effectiveness, each section was assessed using an internal cleanliness rating. Areas with the highest fouling scores received additional PressureWave+ cycles, ensuring the cleaning intensity matched the observed deposit severity.
Removing Deposits Throughout Deep Tube Bundles
The PressureWave+ campaign was completed over 5 days across three primary HRSG corridors and the stack.
Corridor E10
Corridor E11 Preheater #2
Corridor E11 Preheater #1
E12 Stack
Cleaning was performed using controlled PressureWave+ charge sequences through multiple elevations, with a double-charge technique selected for heavily fouled tube banks and reduced-energy cleaning used within the stack to protect the expansion joint. Existing Sky Climber access points were used together with temporary rigging systems installed from the HRSG roof.
Execution was adapted throughout the outage as field conditions evolved. Additional roof access points were created where required to improve rigging and maintain cleaning coverage while protecting internal structures.
Maintaining Safe Execution
Safety planning formed part of every shift throughout the project.
Daily activities included:
- Safety task analyses
- Confined space permits
- Hot work permits
- Client work permits
- Daily walkdowns
- Continuous environmental and equipment inspections
Where elevated temperatures, lightning, or access constraints were encountered, work was paused or modified to maintain safe operating conditions.
HRSG Gas-Side Cleaning Results
Inspection confirmed extensive removal of deep-bundle fouling, with debris accumulations reaching up to 25 inches beneath cleaned tube bundles. Across the planned outage, the project completed 1,584 PressureWave+ events spanning four HRSG sections, providing comprehensive cleaning coverage throughout the targeted areas.
Post-project inspections demonstrated:
- Tube fins exposed throughout previously fouled bundle sections
- Heavy rust fouling removed from deep within dense tube bundles
- Significant debris dislodged from inaccessible areas, confirming cleaning beyond surface deposits
- Clean tube surfaces throughout the stack, where only light sand-like deposits were present
- Internal braces and expansion joints remained in good condition following cleaning
“This project showed how detailed planning and the right cleaning strategy can remove fouling from deep within the HRSG while keeping the outage on schedule. The result was a cleaner unit today and simpler maintenance for future outages.”
– Quinten Ward, Project Manager, IGS
Improving Future Outage Efficiency
The project delivered value beyond the immediate outage. Additional roof access locations were established above Preheater #1 and planned for permanent pipe penetrations, simplifying future PressureWave+ deployments and reducing setup requirements for subsequent maintenance campaigns.
Project observations also found that the double-charge methodology improved PressureWave+ propagation through heavily fouled tube bundles, providing an effective approach for similar fouling conditions in future outages.
Restored deep HRSG cleanliness while improving future outage efficiency.
That’s Asset Vitality.
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