How nozzle design and spray delivery impacts offline compressor washing

contributes to better , reliability and lifespan of your equipment. However, two wash systems using the same detergent can produce very different results depending on how the cleaning solution is delivered.

Your choice of gas turbine compressor cleaning nozzle could be more important than you realise…

What happens during an offline gas turbine compressor wash?

Alongside regular , occasional offline gas turbine compressor washes are recommended to remove stubborn . During an offline wash, the turbine is:

1. Shut down and allowed to cool
2. ‘Cranked’ at low speed (allowing for even distribution of cleaning solution)
3. The compressor is injected with demineralised water…followed by detergent wash cycle(s)
4. The compressor is left to soak
5. Finally, rinse cycles with demineralised water will be carried out until optimum conductivity levels are achieved

What do gas turbine compressor cleaning nozzles do?

inject atomised water/cleaning solution directly into the compressor. They are designed to cover the internal surfaces to carry out the clean.

Effective delivery of the cleaning solution and optimum coverage is extremely important to the end result: if part of the compressor is missed, it will not be cleaned properly.

Operational impact of nozzle design

There’s more to wash nozzles than you might imagine. Regardless of cleaning chemical choice, wash nozzle design impacts:

• Spray pattern
• Droplet size – some plant engineers believe that blade erosion is accelerated by the relatively large droplets produced by the OEM-supplied spray nozzles
• Blade coverage
• Flow rates - flow rate has a huge impact on wash/rinse time, water usage and overall turbine outage
• Rinse efficiency
• Water usage
• Overall wash time and turbine outage

Droplet size and spray pattern are fundamental to achieving effective cleaning results while minimising the risk of erosion.

This has been noted in real-world situations, such as a plant manager reporting a switch to Rochem wash nozzles: “…the smaller droplet sizes and larger area of coverage provided more effective wetting of fouled surfaces and reduced water waste stream by more than 1100 gal.”

It’s worth researching your chosen wash nozzle technology to ensure you are getting the best results each time you conduct a clean.

Field observations

Around the globe, gas turbine plant managers have switched to Rochem FYREWASH® wash nozzles and reported their findings:

GE7FA Example

One customer operating two GE7FA gas turbines was able to complete an offline

compressor wash and return both units to service in approximately five hours using a , which included:

• Rochem offline
• /modified OEM skid

They attributed this to:

• Improved blade coverage
• More efficient atomisation
• Reduced rinse requirements
• Fewer repeat rinse cycles

Based on field observations, some GE7F-series plants typically save around 1,500 to 2,500 gallons of rinse water per offline wash, although results vary by site, operating conditions, fouling level and wash frequency.

Before and after comparison

As part of a combined cycles case study involving GE F7 units at Calpine Westbook, the following observations were noted when using traditional OEM cleaning systems vs a retrofit of the :

While these observations are not guaranteed results, they demonstrate what’s possible with careful product choice.

Find out more

Backed by over 40 years of industry experience, are designed to deliver optimal droplet size and maximum blade coverage for unbeatable cleaning. Using patented technology and high-quality materials, we design, manufacture and test every nozzle in-house to exacting standards. The results speak for themselves.

If you’re interested in finding out more, including about our we would be delighted to discuss how we can help you and your site. with our knowledgeable team.

References:

p. 86 “Re-engineering of wash system increases GT output, reduces waste stream” in Combined Cycle Journal. Second Quarter 2005

p. 86 “Re-engineering of wash system increases GT output, reduces waste stream” in Combined Cycle Journal. Second Quarter 2005