High-speed rotor balancing simulates actual operating conditions, providing the opportunity to optimize a rotor and to make corrections before the rotor is installed. High-speed balancing verifies the mechanical integrity of the rotor design throughout the entire speed range prior to unit installation, and ensures smooth operation of the rotor at rated speed. Elliott can balance rotors up to 275 inches in length, 96 inches in diameter, with journal diameters up to 11 inches and rotational speeds up to 30,000 rpm.
Elliott' state-of-the-art, high-speed rotor balance facility features computer-aided balancing and one of the largest balancing chambers in the world, with an underground bunker and control room. The bunker chamber is operated under vacuum which allows balancing of fully bladed rotors (turbines, compressors, expanders, etc.) under running conditions. Our facility has two sizes of bearing pedestals that can accommodate rotor weights ranging from 150 lbs to 27,700 lbs. Both bearing pedestals can accomodate the use of either tilt-pad or liner type bearings. Elliott maintains a wide range of standard size tilt-pad journal bearings, and also designs and manufactures special bearings for non-standard applications.
High-speed balancing a rotor involves running a rotor to overspeed, which results in the removal of temporary static rotor bow, residual stresses and the effects of shrink fits and blade seating. Rotor components can shift as the rotor is run up to its overspeed limit, causing changes in both the vibration amplitude and phase angle. Without performing a high-speed balance, these changes would occur during the unit mechanical test or on-site. With high-speed balance, these changes occur before balance corrections are made.
Benefits of High-Speed Balance
- High-speed balancing of flexible rotors is more effective than low-speed balancing because low-speed balancing does not reveal where unbalances exist at operating speed.
- Mechanical integrity of the rotor is verified throughout the entire speed range prior to installation.
- Sensitivity and balancing accuracy are increased due to the lower mass and greater flexibility of high-speed balance pedestals compared to the more rigid supports typically used on low-speed balance machines.
- After high-speed balance, the calculated rotor response can be verified. This is useful when a mechanical test of the rotor in a casing is not practical, such as for spare rotors, re-built rotors and re-rated rotors.
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