RETROFIT OF A STEAM TURBINE WITH DRY GAS SEALS

摘要

The solution to a chronic utility problem, with a critical natural gas compression unit, at the Ammonia plant at Du Pont's Beaumont, Texas facility, is described. The most critical problem, chronic steam leakage from the turbine and subsequent oil system contamination, was corrected by the installation of noncontacting spiral groove seals. In addition, vibration problems caused by coupling lockup and subsequent premature coupling failure were solved by replacing the grease lubricated gear type coupling with a nonlubricated flexible coupling. A feature of the coupling is a keyed hub, designed for hydraulic removal. The turbine was sensitive to minor upsets and a rotordynamics study was done. The coupling and seal changes were both done at the same time. The unique features of these designs and measures taken to ensure proper application are addressed along with shop fabrication, field installation, and subsequent operation requirements. A description of project justification of reduced maintenance costs and avoided investments is also included.