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120 Gas Turbine Handbook: Principles and Practices
installing a high efficiency barrier filter downstream have not been
widely accepted due to the initial cost of that configuration.
Since site conditions may change during the life of the gas turbine
plant, it is advisable to periodically test the environment and
the effectiveness of the inlet filter system. This is particularly appropriate
if major changes in surroundings are evident. Contaminants
such as salts can be present in sufficient quantities and in the range
where filter effectiveness is inadequate. This situation will, in time,
result in significant sulfidation corrosion of turbine hot gas path parts
(primarily, the turbine blades and turbine nozzles). A properly functioning
filter system will protect the gas turbine from erosion, corrosion,
and fouling; and help achieve performance, efficiency, and life
expectations. However, a filter system that is not functioning properly
exposes the gas turbine to these undesirable elements resulting in
shorter time-between-overhauls (TBO), reduced power output, and
increased fuel consumption.
Operators may first become aware of problems when their units
require more frequent compressor cleaning to maintain power output.
Or they may find evidence of erosion, corrosion, or contaminant
Figure 8-3. Courtesy of Farr Filter Company. The cartridge or cannister
filter proved to be an extremely effective filter for desert and
arctic environments. Part of its success is attributed to the self-clean
feature designed into the module.