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Table 2 - Results of case study 2
High velocity system 2 stage medium velocity system
4100 m3/h, filter
Air flow 7200 m3/h, filter Cam-Flo XMGT, F7
Pre-filter stage bag filter G4 CamGT 4V-300; E12
Final filter stage bag filter M6 478 Pa
-52%
Intial pressure drop over system 996 Pa
Reduction in air resistance
cartridge solution that has three times the amount of losses due to high pressure loss through the inlet
media, compared to the original setup, for a significantly system. Also, filtration efficiency for small particles are
higher dust holding capacity. The new deep filters did significantly lower than those of a low- to medium
not only replace the existing cartridge filter, but also the velocity system. In this case the operator was facing
F7 bag filter used in the pre-filter stage. To avoid filter replacement every six months and the filtration
turbine fouling and engine degradation effects, the efficiency did not reach over 70% on 4µm particles
filtration grade has been raised from F7 to F9 which would equal M6 filter class according to
(EN779:2012) in the pre-filter stage, and from E10 to EN779:2012.
E12 (EN1822:2009) in the final filter stage.
The CamGT E12 offers >99.5% MPPS efficiency – High velocity systems have the
meaning that it collects at least 99.5% of the particles advantage of reduced size, weight and
most difficult to filter (approx. 0.1 - 0.2 µm in size).
Particles of all sizes, both bigger and smaller, are lower initial cost. A disadvantage is
filtered more efficiently. that there are performance losses due
to high pressure loss through the inlet
Results of case study 1
system. Also, filtration efficiency for
Not only is the turbine significantly better protected small particles are significantly lower
with the CamGT 3V-600 E12, the initial dP has also than those of a low- to medium velocity
been reduced to 200 Pa at 4400 m³/h, compared to
the 250 Pa with the original filter setup. After six system.
months of operation, pressure drop has remained low
and stable even during humid conditions and the A new air intake system was installed on one of two
engine performance has been improved significantly neighboring compressor packages (16 MW aero
(table 1). derivative gas turbines). Past experience from
filtration offshore pointed towards a multiple stage
Case Study 2 filtration system but the weight and space
restrictions limited the options to a 2 stage system.
High velocity system replaced by The harsh environment offshore called for a solution
medium velocity deep filter solution with high resistance to humidity and salt. If salt is
ingested in the turbine the operator face the risk of
One of the world’s leading oil & gas companies had irreversible damage to the turbine and extremely
severe problems with the operation of their gas costly downtime for engine overhaul. The filtration
turbines offshore, with frequent filter replacement efficiency must, according to experience be above
intervals and engine degradation. Many of the turbines 99%, so the filtration grade was set to E12
also suffered from corrosion damages due to poor (EN779:2012).
filtration efficiency. The new air intake system had a first pre filtration
The fleet of gas turbines for mechanical drive, 16 - 30 stage, a bag filter for applications in high humidity
MW, were all equipped with high velocity systems. A filtration class F7. The final stage was equipped with a
high velocity system is normally a one stage filtration CamGT 3V-600 deep filter with more than 50 m²
system with a droplet separator before and after the effective filtration media.
filtration stage. High velocity systems have the This situation with two air intakes in identical
advantage of reduced size, weight and lower initial environments provided an excellent opportunity to
cost. A disadvantage is that there are performance demonstrate the benefits of employing a high efficiency
deep filter solution (table 2).
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