Design Modifications And Active Balancing On An Integrally Forged Steam Turbine Rotor To Solve Serious Reliability Problems.
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Date
1998
Journal Title
Journal ISSN
Volume Title
Publisher
Texas A&M University. Turbomachinery Laboratories
Abstract
This paper describes the design modifications and active
balancing on a 19,000 hp integrally forged steam turbine rotor to
improve its dynamic characteristics and reliability. The turbine was
purchased as a replacement for an identical turbine used in a syn
gas train. Ever since original installation, the turbine had been
plagued with high vibration problems on the coupling end,
excessive bearing temperatures, and reduced coupling life. A
rotordynamic analysis proved that there was sufficient separation
margin between the turbine's operating speed and any critical
speed. However, at operating speed, the rotor had a high vibration
response at the coupling, even with a very small unbalance. A
design modification was thus incorporated on the rotor to make it
less sensitive to unbalance. At operating speed, this modification
lowered the predicted coupling end shaft deflection to
approximately a third of its original value. An active balancer was
then assembled on the rotor to provide the flexibility of online trim
balancing. The replacement turbine has been installed and is
operating with the lowest vibration and bearing temperatures in the
compressor train's history. Presented in this paper is an overview
of the rotordynamic analysis, the shaft welding technique used to
accomplish the rotor design changes, and the balancing with the
active balancer. The techniques presented in this paper can be used
to improve the mechanical reliability of other machines with
similar problems.
Description
Lecture
Pg. 67-76
Pg. 67-76