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Best Practises for Gas Turbine Compressor Cleaning

23/09/2019

Why do compressors need cleaning?

Through normal use, your gas turbine compressor accumulates foulants which has a negative impact on efficiency.
 
Contaminants including salts, hydrocarbons, sand, oil and grease enter through the air supply and lube system, and gradually coat the compressor blades. This actually changes the shape of the blades meaning air doesn’t flow through the compressor as it should. 
 
The inefficient system not only requires more fuel to run, but there is an increased risk of damage to your turbine if the problem is ignored.  
 
Through a properly implemented cleaning schedule, you can remove foulants before they become a problem. This maintains an efficient system and avoids the costly downtime associated with repairs. 

How do I know if my compressor needs cleaning?

The best practise when it comes to compressor cleaning is to implement a regular schedule which includes both on line and off line cleans. If you keep on top of compressor cleaning, you shouldn’t notice a build-up of foulants. 
 
However, there are some tell-tale indicators that may signal your compressor needs cleaning:
  • Reduced
    • Head
    • Capacity
    • Efficiency
    • Pressure ratio
  • Increased
    • Speed
    • Temperature
    • Power consumption
    • Intercooler pressure drop
    • Vibration, thrust bearing load
    • Balancing line differential pressure
 
As a rule of thumb, you should clean the compressor before you notice any of the following:
- A  2% reduction in power
- A 2% increase in exhaust temperature 
- A 2% decrease in compressor discharge pressure
Any of the above is the equivalent to a costly 4 - 5% reduction in power output. 
 
Choosing the right products and equipment
 
Once you’ve decided to clean your compressor, it’s important to use the right products and equipment for a safe, thorough clean. The chemicals you use should meet the OEM specification and for water soluble deposits and synthetic oils, select a cleaner with a detergent base. Mineral oils however are best cleaned with a solvent based product. 
 
FYREWASH is a range of specialist chemicals perfectly suited to compressor cleaning with a product designed for the full spectrum of foulant types.  
 
Rochem also design and install the hardware required for on line and off line washes. Contact us to discuss your specific requirements and we can advise and provide the perfect match for your turbine cleaning schedule.  
 

How to clean a compressor – off line 

A standard off line wash includes the following:
6 MW gas turbine: 20L chemical + 80L water injection 
15 min. soaking
100L water rinsing 
Repeat if necessary
 
Technique
  1. Shut down the gas turbine and allow it to cool. 
  2. To prepare the engine for cleaning, open the drains and IGV.
  3. Once fully drained, close the bleed valves.
  4. Begin cranking the engine on starter.
  5. Inject cleaner fluid + water, commonly heated to 38⁰C - 68⁰C, into the compressor.
  6. The engine should then be soaked at standstill to allow the chemicals to fully break down the foulants.  
  7. Rinse off the foulants and cleaner fluid with clean water.
  8. Restart the engine to dry it out. 

Results

By following this best practise for off line compressor cleaning you can fully restore 100% recoverable lost performance. 
 

How to clean a compressor – on line

A standard on line wash includes the following:
  • 6 MW gas turbine: 20L chemical + 80L water injection 
  • 100L rinsing: 
    • Every day with water 
    • Twice a week with chemical + water

Technique

  1. Leave the turbine running as normal: full speed, full load.
  2. Cleaning solution + water is injected through a fixed on line leaning manifold.
  3. The engine is soaked and the chemicals break down foulants. 
  4. Chemicals and foulants are rinsed off with clean water.

Results

For best results, on line cleaning should complement thorough off line cleans. These ‘little and often’ washes prevent foulants from building up too quickly, maintaining a healthy, efficient compressor.
 
In summary
 
It’s important to maintain an efficient compressor through a regular cleaning schedule combining off line and on line cleans. The choice of equipment and detergents plays a big part in achieving the desired results, but once your schedule is implemented, you should enjoy a reliable, productive turbine.    

Find out more

If you’ve got any questions or would like help deciding on the best detergents and equipment for cleaning your gas turbine compressor, get in touch. Our friendly, knowledgeable team will be happy to discuss your specific requirements. 

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