REDESIGN OF THE LAST TWO STAGES OF A MECHANICAL DRIVE STEAM TURBINE

摘要

A six stage mechanical drive steam turbine rated at 13,300 hp was installed at a petroleum facility in Texas to drive a multistage centrifugal compressor used in recycle gas service on a high pressure hydrogen cracker. Since its installation, there has been a failure of either the fifth or sixth stage blades at intervals of 18 months to two years. The blades failed due to high cycle fatigue initiating in the dovetail root attachment. To alleviate this problem, wider, more robust blades with improved aerodynamics were designed, which include Z-shrouds and a new root dovetail attachment with a lower stress concentration.