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Air Inlet Filters….Can They Really Make a Difference? This brief discussion from our Engineering Department will give you fresh perspective on air inlet filtration.
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Do you view replacing the air filter elements for your gas turbine inlet system as – ho hum -- just necessary maintenance? If so, you’re probably not giving enough technical consideration to selecting a replacement filter.
But consider this: field research has shown that a highly efficient filter can actually improve turbine performance – even dramatically -- by minimizing compressor blade fouling. One study* showed turbine performance varying as much as 8% of turbine output between a system using a low efficiency filter and one using a higher efficiency filter over a 3-month period.
The performance of a filter is defined by 3 main parameters -- pressure drop, efficiency and service life -- which have a direct impact on the performance of a combustion gas turbine.
(1) The pressure drop of a filter is simply its resistance to airflow – that is, the energy loss incurred moving air through the filter – and is typically measured in mm of water or inches of water, the lower the better. The effects of high filter pressure drop are well understood: it reduces turbine output.
(2) Filter efficiency defines the amount of contaminant that is removed from the turbine inlet airstream, and is typically measured in terms of the number of particles removed as well as their size. A highly efficient filter, especially one that removes particles smaller than a micron in size, can improve turbine performance by minimizing compressor blade fouling.
(3) Service life is the period of time the filter is in operation before it must be replaced because contaminant loading is causing pressure drop that exceeds the recommended level for the turbine. A filter with a long service life at low pressure drop results in a low mean operating pressure drop of the system over time, resulting in more turbine output over time.
The best air filters provide all three characteristics: low pressure drop, high efficiency, and long service life. Economic analysis shows that selection of a high performance air filter (one that optimizes its filtration performance for its operating environment) results in greater operating profit of a gas turbine system.
At left, we see the very small air passages in the blades, as well as the dire consequences from FOD.
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