ELLIOTT'S HIGH SPEED BALANCE FACILITY
Your Low Cost Investment in Reliability
At speed balance facility
The Elliott-Jeannette facility has been in the high speed balancing business since 1980. Several thousand rotors have been balanced including Elliott designed compressor & turbine rotors as well as non-Elliott apparatuses. In 1999, Elliott installed a new state-of-the-art, high-speed balance facility, which consisted of a new control room and underground bunker. The bunker chamber is operated under vacuum, which allows balancing of fully bladed rotors (turbines, compressors, expanders, etc.). Our very experienced staff not only consists of (2) full time balance technicians and (2) full time test engineers, but also includes on-site corporate engineering staff.
Advantages of High Speed Balancing
High Speed balancing provides the opportunity to optimize the rotor and simulate actual running conditions. Any required corrections can be made at several balancing planes. This guarantees smooth operation of the rotor at rated speed.
Mechanical integrity of the rotor design is verified throughout the entire speed range prior to unit installation. Not performing a high-speed balance could significantly delay project schedule and increase costs.
Sensitivity and balancing accuracy are actually increased due to high-speed balance machine pedestal flexibility and lower mass as compared to more rigid machinery supports such as those typically used on low speed balance machines.
The high speed balance facility can be used to verify calculated rotor response when a unit mechanical test in a casing is not practical for rotors such as the unit spare, service or re-builds.
Why not just low speed balance?
High-speed balance closely simulates actual mechanical operation conditions where rotor-bending deflection modifies the resulting forces from residual unbalance. Low speed balance only measures the sum of unbalance at two journal locations with the rotor in a rigid state. Unbalance can still exist at operating speed; especially in flexible rotors where bending of the rotor can exaggerate a specific unbalance distribution.
Facility Accommodations
Our facility uses two sizes of bearing pedestals that support rotor weights ranging from 130 lbs. to 30,000 lbs.* Both bearing pedestals will accommodate the use of either tilt-pad or liner type bearings. Elliott maintains a wide range of standard size tilt-pad journal bearings. If our standard bearing does not fit your specific application, a special bearing will be designed and manufactured in a reasonable time frame to meet your planned schedule. Below are the specifications that apply to each size of pedestal.
DH4 Pedestal (Manufacturer: Schenck Trebel Corp.)
- Maximum rotor weight: (approx) 2,750 lbs.
- Maximum speed: 27,000 RPM
- Maximum rotor component diameter: 96 inches
- Maximum rotor length: (approx) 303 inches
- Journal Bearing Diameters: 2.0 to 5.0 in.
DH7 Pedestal (Manufacturer: Schenck Trebel Corp.)
- Maximum rotor weight: (approx) 30,000 lbs.*
- Maximum speed: 12,000 RPM
- Maximum rotor component diameter: 96 inches
- Maximum rotor length: (approx) 303 inches
- Journal Bearing Diameters: 5.0 to 11.0 in.
*Rotors weighing slightly higher than 30,000 lbs. may also be a candidate for our facility depending on specific conditions. These conditions will be reviewed by our engineering staff upon request.
In summary
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.