The Importance of Filtration

Today’s operators demand high availability and low maintenance downtime. But in both urban and rural environments, the operation of a gas turbine is a continual battle against the elements. In particular, because of the very large quantities of air that turbines require for operation, airborne contaminants can pose a significant challenge to the ongoing health of rotating equipment.

The main purpose of any filtration system is to protect the turbine from harmful airborne contaminants. Typically, harm is caused in the following ways:

Erosion
Relatively large (greater than 10 microns) particles – and occasionally droplets – impact compressor blades at high velocities. Over time the damage can be significant enough to change the aerodynamic characteristics of the compressor. In extreme situations, where very poor intake systems are in use, catastrophic damage can occur.

Corrosion
Even relatively small quantities of a corrosive substance entering a turbine can cause substantial damage in a short period of time. For example, one of the most common contaminants associated with turbine corrosion is salt (NaCl).

Fouling
Some contaminants are predisposed to collect on compressor blades. This can be because they are sticky in nature, have a low melting point or perhaps because another contaminant, such as an oil mist has precoated the blades. Whatever the reason, the build-up over time of this 'fouling’ will impair the performance of the compressor.

Plugging
A similar process to fouling can lead to the blockage of blade cooling passages. These ‘plugged’ cooling paths will eventually lead to the blade operating at a higher than desired temperature, and can lead to blade failure.

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