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Why compromised filters lead to decreased gas turbine efficiency and what you can do about it

22/10/2021

It’s an exciting time for gas turbine technology. We’ve seen huge advancements in recent years and models such as the H-class are proving investment in this sector is well spent.  
 
Aside from being more reliable, newer turbines are demonstrating greater efficiency. Needless to say, efficiency is the route to profitability, so anything that can boast better efficiency is welcome to the industry. 
 
Unfortunately, there are several technological and environmental factors that impact gas turbine efficiency. Some can be controlled e.g. your gas turbine model and your choice of fuel, and some are out of your hands e.g. the climate and airborne contaminants. 
 
 
At Rochem, we’ve helped countless gas turbine operators recover lost performance. Experience has shown that axial flow compressor deterioration during operation accounts for the major portion of gas turbine related performance loss compared to the new and clean condition. When looking at overall performance loss, approximately 70% can usually be put down to compressor deterioration due to blade fouling.
 
So, how can we improve efficiency, regardless of whether the gas turbine is the latest version or an older model? The answer is to tackle compressor fouling
 

New, improved and highly sensitive

The greater efficiency of newer turbines is down to many factors, including:
  • Printing technology facilitating precise and elaborate components 
  • Improved aerodynamic design 
  • Ability to work at higher firing temperatures 
  • Better air cooling technology 
  • Upgraded thermal barrier coatings
  • Superior air filters 
All of this is fantastic news and allows turbine operators to produce more power, more efficiently. However, the precise components are extremely sensitive while the higher working temperatures can accelerate fouling issues. Even the advanced coatings are susceptible to physical and chemical erosion if steps are not taken to protect them. 
 

How is fouling related to efficiency?

It’s an unavoidable fact that air contains contaminants. The types and quantities of these contaminants will vary depending on where you take your sample, but you could expect sand, pollen, exhaust gases, salt and all manner of other particles to be present in the air at your gas turbine site. Even water droplets from fog can decrease the efficiency of your turbine. 
 
Although we can’t usually see these contaminants with the naked eye, once they are drawn into the gas turbine compressor you will certainly notice their presence. They can physically erode the inner workings of your compressor and, when subjected to high temperatures and pressures, become baked onto compressor blades. This alters the aerodynamics thereby reducing efficiency. 
 
If your gas turbine site is close to the sea, airborne salt can cause even further problems. The chloride may start pitting corrosion of compressor blades while the sodium can form sodium sulphate by combining with sulphur in the fuel. The latter can be particularly devastating as it tends to cause damage to the very expensive hot section components.  
 
It’s essential that you keep the inner working of your gas turbine compressor free of contaminants. While filters help to reduce the foulants present, process compressor cleaning will protect the turbine blades from fouling and erosion, helping to maintain an efficient, reliable turbine. 
 

What can I do to further boost efficiency?

Whether your gas turbine is an old model or brand new, there are almost certainly steps you can take to boost and maintain efficiency
 
Filters certainly help combat the issue of fouling, but even the newest, most expensive filters cannot remove 100% of airborne contaminants and they can also enter the system via other means e.g. lubricating oils. So, you will inevitably experience some fouling of your compressor blades. 
 
Alongside a regular maintenance schedule, compressor washing is a fantastic way to sustain or even boost the efficiency of your gas turbine. On-line washes can be performed during normal turbine operation, simply and effectively removing any troublesome contaminants that make it through or bypass the filters. This keeps your compressor running as it’s designed: with optimum airflow and maximum efficiency. 
 
To complement on-line washes, less regular manual off-line washes are recommended to thoroughly cleanse foulants and restore your compressor to a clean, aerodynamic state. 
 

Find out more

There’s no doubt that filters play an essential part in maintaining efficiency in a gas turbine compressor. However, no matter how sophisticated the filter, it cannot do the job on its own. We need to step in with a regular cleaning schedule to ensure the turbine continues to run at peak, profitable performance. 
 
If you’ve got any questions about our gas turbine compressor cleaning equipment and specialist chemicals, get in touch.
 
Our knowledgeable team will be happy to discuss your specific requirements and help you regain lost power at your site. 
 

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