The gas turbine inlet air quality is highly critical for overall system performance. The turbine filters that are designed in this regard, are believed to deliver efficient performance characterized by low pressure drop, long service life and low maintenance costs.
When an air quality entering the gas turbine is not controlled well, various consequences are resulted. Some of the most general degradation processes are discussed here, which further highlight the significance of turbine filters for preventing poor inlet filtration.
Erosion happens when liquid or solid particles of size around 10 nano-meter and bigger, affect rotating and static surfaces present in the gas turbine. The particles affect the surface and eliminate small particles of metal that finally cause changes in the surface’s geometry. These changes cause diversions in the air flow, making the smooth surfaces rough, altering clearances and reducing cross-sectional areas of the metal elements possibly in high stressed regions. Erosion is the process that is non-reversible; hence, the gas turbine elements should be replaced so as to restore the original condition. The particle of 10 nan-meter and bigger, however, can easily be removed through commercial turbine filters.
Fouling that affects compressor blades is a sensitive process that results in poor performance of gas turbines with the passage of time. Fouling usually happens when particles are stick to annulus surfaces and airfoils. Particles causing fouling are usually smaller than 2 to 10 nan-meter. Oil mists, smoke, carbon and sea salts are general examples.
Fouling is usually controlled by a proper air filtration system or turbine filters and often reversed to certain level by detergent washing of the parts. The adherence is affected by water or oil mists. This leads to accumulation of material that causes more surface roughness and some changes in the shape of airfoil. Fouling, thus, decreases the gas turbine performance.
These consequences can be avoided by using high-quality turbine filters backed by advance air filtration mechanisms for commercial environments.