How To Restore Lost HRSG Performance
By Jessie West | January 15 2021
Restore Lost HRSG Performance
Today’s power market is uncertain with fluctuating fuel costs and demand. This means it’s essential for companies in the industry to maximize production and efficiency. However, small changes in equipment condition can significantly impact productivity, especially with heat recovery steam generators (HRSGs). Fortunately, these issues can be resolved with comprehensive cleaning services from experienced providers.
Why should you clean your HRSG? Read on to learn how cleaning can restore lost HRSG performance and how EAI’s cleaning technologies can help.
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HRSG Fouling
HRSG components can degrade over time because of multiple factors. One of the most common issues, however, is fouling, which is the buildup of deposited materials on the HRSG finned tubes.
Numerous conditions can cause fouling in an HRSG:
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- Rust: Rust is the most prevalent type of fouling as most HRSG components consist of carbon steel, which is vulnerable to oxidation. Oxidation of these components increases with water and water-vapor levels, as well as temperature. Oxidation buildup results in masses forming in the HRSG, but it can also weaken the material, potentially resulting in breakage.
- Insulation: Insulation fouling is another common type of fouling often found on heat-transfer surfaces — especially finned tubes. Insulation fouling is usually found in cases where there are extensive liner failures or gaps, which results in insulation getting sucked out and deposited downstream.
- Ammonia salts: Units with selective catalytic reduction systems (SCRs) may see fouling from ammonia salts, which form when sulfur in the exhaust gas reacts with ammonia used for nitrogen oxide (NOx) control. These chemicals create salt precipitants, which collect on cooler metal surfaces downstream in the HRSG unit. Once deposited, these salts can be difficult to remove as they form a dense and damaging coating.
- Sulfur: Sulfur compound buildup is common in units operating with fuel oil, burning high-sulfur natural gas or using sulfur-based odorants for leak detection. Sulfur deposits are highly corrosive, quickly resulting in tube failure if mishandled. Sulfur deposits are also difficult to clean, often jumping down the tube during cleaning to stick to areas further down the line.
These fouling issues can result in tube surfaces becoming insulated from the gas flow, which has significant issues on performance.
Effects of Lost HRSG Performance
Fouling creates significant performance issues in HRSGs over time. As tube surfaces become more insulated from gas flow, HRSG systems encounter the following problems:
- Decreased steam generation: Decreased steam generation reduces steam turbine output.
- Increased backpressure: Increased backpressure reduces performance. If an excessively fouled HRSG reaches or exceeds a designated backpressure limit, this can trigger a turbine trip, shutting down the system.
- Reduced thermal performance: Reduced heat-transfer efficiency reduces the steam turbine’s output.
- More breakdowns and malfunctions: Corrosion from fouling can result in tube parts breaking, causing system shutdowns.
All of these factors result in decreased output, which diminishes the company’s bottom line. Every half-inch of backpressure for a typical F-class HRSG reduces a business’s bottom line by $100,000 annually.
How to Improve HRSG Performance
The question now becomes how to restore HRSG performance and reduce HRSG fouling. There are several preventative measures to help reduce fouling, such as upgrading HRSG components to corrosion-resistant alternatives. The simplest answer, however, is through cleaning.
Most types of degradation resulting from fouling can be prevented and treated through HRSG cleaning. Cleaning offers various benefits, including the following:
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- Improved performance: Regular HRSG cleaning can help regain back pressure and increase performance. Many plants will see a 1-inch or better improvement from cleaning services.
- Increased revenue: Reducing the backpressure in an HRSG by just 0.5 inches will result in a quick payback of tens of thousands of dollars.
- Maximized longevity: Regular cleaning removes corrosive deposits and prevents further deposits from forming. This can significantly extend the life expectancy of HRSG components, reducing the long-term costs of repair and replacement.
Save Money by Cleaning Your HRSG
Several cleaning options are available for HRSGs. CO2 blasting is the most common due to it’s effectiveness and environmentally friendly application.
With CO2 blasting, EAI’s trained cleaning specialist uses a high-pressure compressor to blast CO2 pellets against fouled surfaces at speeds up to 1,000 feet per second. These dry ice pellets sublimate from a solid to a gaseous state, expanding rapidly as they hit the surface, which helps loosen the debris more effectively. Once the debris is free, the specialist then removes it with a vacuum device. This process is non-destructive, produces no secondary waste and can be used for deep cleaning and spot cleaning.
Cleaning using a CO2 ice blast approach can be done as often as needed and is usually employed annually as preventative maintenance. To help you learn more about what CO2 ice blast cleaning is, how to use it and when to schedule cleanings, EAI can assist. We specialize in CO2 ice blast cleaning for HRSG components and can answer any questions you may have about the process.
Get Help From EAI
HRSG cleaning to improve performance and prevent ongoing damage is one of the best techniques to employ for a power company’s bottom line. With EAI’s CO2 blasting services, you can maximize the efficacy of your cleaning solution and increase HRSG performance in the long term.
If you’re interested in CO2 ice blast cleaning for your HRSG, look no further than EAI.
EAI offers full turnkey cleaning systems paired with qualified personnel who can help clean fouling of all types. Whether you’re encountering sulfur deposits, ammonia salts, corrosion, rust, insulation or other contaminants in your HRSG, EAI has you covered.
We partner with our clients to perform cleanings as part of annual maintenance programs, helping them keep their units operating at peak efficiency, and we’re available for emergency cleaning services. We also stay on top of the latest in HRSG news, maintaining attendance in HRSG users’ groups and working closely with original equipment manufacturers (OEMs) so we know exactly what owners and operators need and how to deliver it.
Learn more about why major OEMs recommend EAI as the company of choice for HRSG cleaning. Contact EAI today and ask about our CO2 blasting cleaning services.