Analyzing Imbalance in a 24 MW Steam Turbine

Abstract

Imbalance in critical rotary equipment is one of the most important factors, which should be controlled to prevent great damages. In this case study we are discussing about a 24 MW steam turbine, which drives a propane compressor. The radial vibration on the DE side of the turbine was growing gradually to a high level close to the alarm's value. Using FFTs, time signals, orbit diagrams, and phase measurement led us to believe that the rotor became imbalanced. After tripping and disassembling the turbine, we found out, some blades of the impulse stage of HP section got broken. Changing the rotor with the spare one, and repair the damaged rotor, worked out. It was concluded that using the vibration analysis technique is an effective method to find critical rotating equipment’s faults at the earliest levels. And performing the essential correcting tasks to prevent secondary damages and specially decrease of production.