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Best Practices for Maintaining Gas Turbine Compressor Efficiency

    July 25, 2017

Maintenance personnel know how important cleaning is to maintaining efficient turbines. Airborne particles inevitably ingress into the gas turbine compressor, fouling the air path surface. This leads to reduced efficiency and increased fuel consumption.

The question is whether the cleaning should be done online or offline. Both methods are complementary, and both are important. In this post, I’ll explain the advantages and disadvantages of both methods to help you decide when to use each one.

Causes of compressor fouling

First, let’s examine what causes compression fouling.

The most common issue is blade fouling caused by airborne particles. This is the case about 70 percent of the time. To prevent this, you can install an air filter at the inlet.

Another common problem is oil leakage from the compressor rotor inlet bearing. This causes compressor vane fouling and cannot be reduced by even the best quality filters as oil leakages happen after air filters in the flow path of air.

The resulting drop in air flow and pressure ratio results in “re-matching” of the compressor and turbine and causes a drop in efficiency. Front compressor stages are fouled the most. Therefore, periodic cleaning needs to be done to restore efficiency.

Online cleaning

Online cleaning is performed when the gas turbine is operating and under load. It maintains compressor cleanliness after offline washing and minimizes power losses while ensuring efficiency. Online cleaning also extends the operating period between shutdowns.

The online cleaning procedure involves:

  1. Injecting a mixture of water and chemical detergent via atomizing spray nozzles placed around the compressor air inlet plenum
  2. A flushing period using pure (demineralized) water
  3. Discharging effluent (this usually needs to be treated before disposal)

Online cleaning is generally recommended every three days to weekly. The duration of the wash varies according to the degree of fouling, the turbine size, air quality at the plant location and plant experience.

online vs offline cleaning

Offline cleaning

Offline cleaning is performed when a compressor is dirty in order to restore power and efficiency. This returns the compressor to virtually “new and clean” values.

The offline cleaning procedure involves:

  1. Rotating the turbine at crank speed while a cleaning fluid is injected
  2. Injecting a cleaning fluid made from a mixture of a chemical detergent and water via permanently mounted (or in very few cases hand held) nozzles installed at the air inlet
  3. Draining effluent water from the compressor
  4. Disposing effluent water according to local regulations

Offline cleaning is generally recommended three to four times per year, but this can vary depending upon your plant’s specific operating conditions.

An important consideration

The type and degree of gas turbine compressor fouling is site-specific. Your cleaning program should be adjusted as needed based on your unique situation. Both online and offline cleaning recovers average output power, and both methods complement each other.

Considerations for chemical cleaners

Turbine and compressor cleaners can generally be water-based or solvent-based (detergents).

Detergents enhance the removal performance on deposits, especially from the blades. They’re more beneficial during offline cleaning than online cleaning.

Water-based cleaners are more popular due to environmental and safety considerations. A neutral pH-value is preferred.

Henkel’s turbine compressor cleaning solutions

Henkel offers a line of BONDERITE cleaners that provide proven technology for efficient turbine cleaning.

These cleaners have gone through and performed well in Naval Air Systems Command (NAVAIR) compressor cleaner testing. The tests involved engines fouled to 25 percent power loss that were cleaned three times.

50 cleaners were tested and BONDERITE T-6783 was found to be the best online wash with a 22 percent improvement, and the second best offline wash. The testing also found that detergent cleaners were better than water only.

At Henkel, we have more than 80 years of experience in cleaners and conduct extensive R&D testing to offer new innovations to customers. BONDERITE cleaners are approved by OEMs including GE, Alstom, and P&W and are a cost-effective solution to keep turbines running efficiently

Need something custom?

Our chemists can fine tune chemistries or even develop new cleaning chemicals fast so you can meet your plant specific maintenance needs to improve plant efficiency and also save cost.

Over to you

What questions or problems have you experienced in gas turbine compressor cleaning? Leave a question in the comments section and we’ll be glad to respond.

About the Author, Pradeep Klair

Pradeep is a global market development manager for Henkel providing support for the power segment. He has over 15 years of experience in MRO and has worked in multiple global regions in various roles ranging from sales management, business development, and global market development. Pradeep holds a bachelor of technology degree in mechanical engineering and has received a “mini MBA" from Rutgers University.

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2 responses to “Best Practices for Maintaining Gas Turbine Compressor Efficiency”

  1. LEEMANS says:

    Good morning Pradeep,
    I am an authorized vendor of Henkel for Benelux and my account manager is Bert Bellon from Henkel Belgium.
    Sometimes I sell BONDERITE C-MC 5884 at FLUXYS and also for General Electric Hungary via a central buying in Belgium. Could you me explain witch is the difference between the 3 BONDERITE C-MC 6783 (3-10-50).
    The 3 is too concentrate to meet the specification ML-C-85740 B TYPE 2
    The 10 is ready To use, and the 50 is concentrated and used at 20% by volume. But concretely at the level of analysis of the customer’s need how do I suggest one rather than the other solution ? may be have you some pictures of a videofilm of this application ?
    Can I had your article on my internet site

    • Brandon Gearing says:

      Hi, thank you for your question. I will forward this to our team in Belgium to help and they will contact you at the email address you provided. – Brandon

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