6 COMPACT, HIGH-VELOCITY FILTRATION Given the severe restrictions on space on board marine vessels, as already noted a key characteristic is the requirement for a compact, aerodynamically highly optimized, combustion air intake system. This necessitates high air stream velocities through the system while still meeting the very stringent airflow distortion limits at the GT face as specified by the GT OEM - an uneven velocity airflow creates more turbulence, is inefficient and leads to increased pressure drop across the system, all of which adversely affects GT performance. While applications such as FPSOs or FLNG vessels offshore already require compact high-velocity filtration systems, for naval propulsion this requirement is only enhanced. An inertial marine vane separator is the first stage. In this component, an assembly of vanes force the air stream to change direction multiple times, which removes large diameter liquid droplets and bulk water. Downstream of this is a second coalescing filter stage, where any fine droplets that pass through the first vane separator are Given the intake filters are required to run at extremely high speeds this design obligation can potentially increase the opportunity for materials such as salt water to be carried through into the turbine internals. This danger becomes even more likely in rough seas or when travelling at high speed during pursuit or in combat. In naval applications operating at extremely high airflow velocities, the air intake filtration system to prevent salt water and particulate ingress is most commonly provided by 3 stages. forced to coalesce/agglomerate, meaning they become larger and are then removed entirely from the airstream by the third and final stage marine vane separator. All of this needs to be completed with the lowest possible differential pressure drop. Stage 1 Stage 2 Stage 3 Bulk water removal Coalescing and particulate removal Final salt removal Airflow
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