Soot - How can something so tiny be causing so much problems for Gt´s and for Filtration

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Soot is one of the most problematic air borne particulate matter causing severe compressor efficiency loss and shortening the lifetime of filters – so it´s the nightmare of every Power plant operator in Industrial areas, close to heavy traffic or in Refinery environment.

What is soot?

Soot is Organic carbon particle produced in incomplete combustion of carbon containing fuels. Typical origins are Diesel/oil combustion engines in traffic and electricity production as well as Refinery processes – even GT´s produce small amounts of soot even while firing on clean natural gas.  Soot particles are very small in size – typically well below 0,4um – and it´s the small particle size making Soot so dangerous by enabling soot particles penetrating e.g human lungs and even bloodstream, not to mention penetrating through standard GT inlet air filtration.

Why is soot so harmful for Gas Turbine?

In Gas turbines soot is causing heavy degradation by forming deposits to Compressor blading causing loss of efficiency.

Soot is sticky and has anti-hydrophobic properties lowering the surface tension of water, which makes soot resistant against washing.

Typically soot can be removed from the compressor only by mechanical cleaning during major outages.

Why is soot so harmful for Filters?

Soot particles are sticking to every surface – even filter fibers or ePTFE membranes

In Depth loading filtration media the Soot covered fibers will lose their hydrophobic properties and causing also a reduction in filtration efficiency.

Depth loading media can withstand soot better than surface loading media as there is simply more fibers to catch the soot.

In F-class filters loss of efficiency due to soot exposure can be up to 10%-units, which will further increase the soot loading of compressor blading causing even more Degradation.

For electrostatically charged filters the loss of efficiency is even greater causing even higher soot loading on compressor blading.

On surface loading media, like ePTFE or nanomembrane the surface is more vulnerable to soot – blocking of membrane “holes” will cause rapid increase in dp ending the lifetime of surface loading filters.

How to protect the GT against soot ?

Soot particles are very small in size, which means that high percentage is penetrating through the Pre- as well as the Fine filters. Due to the sticking properties of soot there is little benefit of pulsing the filters – and since pulse filters are relying on surface loading media they will not work well in high soot environment.

No filtration media can recover from soot so the only way of surviving in high soot environment is to have as much filtration fibre surface as possible – this also means a preference of depth loading materials over surface loading materials.

Eagle Filters´ 3-stage depth loading filtration solutions ensures you the best possible operation in High Soot Environment

To cope with high Soot environments the Eagle Filters filtration system is designed to: 

  1. All filter stages are designed with depth loading materials cascading the soot loading into Pre- and Fine filter stages as much as possible ensuring a long service life for EPA filtration stage.
  2. All filter stages can be designed with maximum filtration media to survive longer in high soot environment – our MAGNUM E11 can be equipped with 54m2 of filtration media to have maximum lifetime
  3. Cascading the filtration to G4/F8/E11 the overall filtration efficiency is above 99,2% keeping your Compressor degradation minimum without excessive dp

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