Development Of Abradable And Rub Tolerant Seal Materials For Application In Centrifugal Compressor And Steam Turbines.

Abstract

The use of abradable and rub tolerant polymer seals to reduce leakage between rotating and stationary members in centrifugal compressors and steam turbines has increased over the years. Abradable materials such as mica-filled tetrafluoroethylene (TFE), nickel graphite, and aluminum alloy containing silicon/polyester are the most commonly used and have gained acceptance in the marketplace. This paper highlights the development of anew abradable silicon rubber adhesively bonded to a metal substrate. The abradability of the material was found to be excellent with no damage to the rotating member. For rub tolerant polymer seals little data are available on the effects of an aggressive rub with relation to deflection and wear at various temperatures. A series of test was done on labyrinth seals manufactured from various forms of carbon fill polyetheretherketone (PEEK) and polyamideimide (PAI). these test evaluated their mechanical performance at low temperatures, room temperatures, and high temperatures. The results of the tests indicated that at room temperature and low temperatures, the seals exhibited acceptable deflection properties without damage to the rotating shaft and minimal material loss from the labyrinth teeth. However, at high temperatures of 150°F, the PAI material had greater deflection values than the two types of PEEK, which resulted in the PAI exhibiting greater tooth height loss compared to the PEEK materials. For steam turbines, nickel chrome and nickel graphite were tested in a steam turbine and results are highlighted. This paper also shows the efficiency improvement for applying abradable seals to centrifugal compressors and steam turbines.