Gas Turbine Intake Filters
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Energy offshore is mainly generated by gas turbines. Degradation of gas turbines is a source of considerable expenses for the oil and gas producing companies, and contributes to increased emissions to the atmosphere. Filtrating the gas turbine intake air has shown to be effective in terms of reducing the rate of gas turbine degradation. However, filtration systems also suffer from degradation. This thesis covers relevant aspects in understanding filter deterioration.Particles accumulated by offshore air filters, have proved not to be distributed evenly over the total face area of the filter assembly. The highest variation within a specific assembly was 463 to 1315 g, which constitutes a factor above 2.8. Varying operating conditions is the attributed cause, realizing that the filters are heavily affected by site specific installations and activities on and around the offshore facility. The pressure drop over a filter has shown to increase with high values of accumulated weight. However, the particle type and its distribution over the face area are the determining causes. Tests have demonstrated that moisture brings accumulated particles through the filter. A thin and light filter with high filtration efficiency proved to be extremely vulnerable to moisture, while a more rigid structured filter with lower filtration efficiency, was much more resistant. Given the type of filter, the penetration effect is determined by the total amount of water entering.Tests on a filter with a claimed salt-removal efficiency of 99.96%, when in combination with a vane separator, proved the initial effciency of the filter to be 63%, which fell to a minimum of about 30% as more salt was injected.When comparing the performance of an offshore degraded filter to one degraded in the test rig by salt-injection, the results were remarkably alike for filters with similar amounts of accumulated particles. This makes it possible to predict the offshore performance of a specific filter. This document includes new methods for testing that have produced interesting and important results. The findings shed new light on the current state of affairs for offshore air filtration. The thesis constitutes a good foundation for continuing work on this subject, and for developing new standards for filter testing.