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How to maintain gas turbine performance in a corrosive environment

10/11/2021

Whether your site is in the driest desert or miles offshore, you will face the issue of contaminants within your gas turbine compressor. Once there, these foulants can impact productivity, damage components and even cause costly unscheduled shutdowns if you don’t address them in good time. But where do contaminants come from and what can you do about them?

 

Where do contaminants come from?

Fuel

Unfortunately, whatever kind of fuel you use, it is unlikely to be a totally pure product. Natural gas for example consists mostly of methane but also has small amounts of nitrogen, CO2, ethane, propane and hydrogen sulphide. The latter is of most concern when it comes to compressor blade corrosion and, if water contaminates the fuel, you may also note the presence of alkali metals.   
 
The contaminants in liquid fuels depends on the type you choose. You may have residues from the fuel’s crude origin; contaminants introduced by poor handling during processing; or during transport. 
 

Air

No matter how good your air filter, you’re likely to face the issue of airborne contaminants entering your gas turbine compressor. As you’d expect, the type of contaminants vary site-to-site and even day-to-day but you could note:
 
  • Salt
  • Dust
  • Sand
  • Exhaust fumes
  • Chemicals
  • Fertilizers
  • Mineral ores
Sea salt alone introduces chloride, sodium, sulphates, magnesium, calcium and potassium to your compressor. The physical particles of salt can cause erosion but you also have the issue of corrosion if the salt is mixed with water. 
 

Water

Untreated water can introduce a range of contaminants including sodium and potassium which will corrode the delicate inner workings of your turbine compressor.
 

What issues do contaminants cause?

Contaminants cause three main issues in a gas turbine compressor:
 

1. Fouling 

Some contaminants will fuse to compressor blades, interrupting the aerodynamics and thus reducing efficiency. 
 

2. Erosion

Contaminants can physically erode the surfaces with which they collide, especially under the extremely high pressures found inside gas turbine compressors.     
 

3. Corrosion

Some contaminants will chemically react and corrode compressor components. Many of the contaminants mentioned can cause corrosion and the extremely hot temperatures of the compressor accelerates the problem.
 
‘Hot corrosion’ is accelerated oxidation when molten salts react with the compressor components. The higher the levels of contaminants including chlorine, fluorine, potassium, sodium, sulphur, vanadium and lead, the worse the corrosion.  
 
Some contaminants e.g. sulphur can dissolve in water to become acidic, further corroding your compressor. 
 

How to maintain compressor performance?

The goal for every gas turbine is to be as productive and profitable as possible. When contaminants threaten these goals, it is essential to tackle them: regaining lost power and boosting efficiency. This is precisely our area of expertise. 
 
Alongside minimising the introduction of contaminants by using an air filter, purifying any water used and ensuring careful fuel handling, you can remove inevitable contamination from the gas compressor with specialist cleaning
 

Gas turbine compressor cleaning

Our range of gas turbine compressor equipment and chemicals is the chosen technology for sites around the world. Special nozzles inject atomised cleaning solution into the turbine compressor during normal operation, effectively cleansing away contaminants without impacting on turbine performance. Complement these on-line cleans with less regular off-line washing to keep your turbine running at peak performance. 
 
Our range of FYREWASH® chemicals are specially designed to combat a wide range of contaminants found in gas turbine compressors. There is a product for every situation: from environmentally sensitive offshore locations to sites operating in high levels of pollution. 
 

Get in touch

In order to run the most efficient, profitable and reliable gas turbine possible, it’s essential to remove contaminants. If you’d like to find out more about how Rochem can help at your site, get in touch. Our knowledgeable team will be happy to talk about your specific requirements.     
 

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