Balancing of High Speed Turbine Rotors.

[uruz]

Balancing of high speed turbine rotors details.
Speed: 4596 RPM
Type of balancing (grade): dynamic as per API-617
Biggest impeller diameter: 1346 mm
Rotor weight: 7286.6 Kg.
i want to know which type of drive system to be used for balancing of such type of rotors.
Unversal Joint drive or Belt drive system.
unversal joint drive means:-drive by coupled drive & belt drive means rotor driven by belt whilw balancing.

 

[Tmoose]

I recall API-617 may include a spec for balancing at operating speed. End drive is about the only way to drive a rotor that needs serious horsepower.

An end drive balance procedure should include indexing the u-joint/drive shaft to test for the driveshaft's influence. There will be some.

 

[metengr]

For our high speed turbine rotors, the turbine repair shops we contract with have a universal joint drive system.

 

[rmw]

I have seen plenty of turbine and generator rotor balance operations and I can't ever recall seeing a belt driven set up. Does your description of belt drive mean that the belt is slung over the turbine rotor itself or is it via a pulley on the end of the rotor. The wording makes me think the former and that would mean that the belt tension would have to be accounted for.

rmw

 

[unclesyd]

We have one balancer that can handle up to an approximately 3000 lb shaft that is belt driven. The shaft sits in 2 roller bearings and the belt is wrapped in a convenient space. The belt is driven by a ten HP DC motor. If I recall the belt is set with idler pulleys and drives the rotor straight down. The whole system is on a floating bearing assembly.

Not ours but similar. Look at the biggest one it can also be belt driven.

http://www.universal-balancing.com/horizontal-balancing-machine.cfm

 

[Tmoose]

Hard and soft bearing balance machines can use belt drive. the trick is to orient the belt tension perpendicular to the measurement direction. Otherwise eccentricity etc can create a 1X signal that the eager-to-please balance machine interprets as unbalance.

Comparing Calcs for HP that can be transmitted with available drive diameters/rpm Vs windage HP may eliminate belt drive real quick. Paper and tape or clamshell housings may reduce windage some, but there's a limit.

 

[corrosionman]

Assuming the turbine could be belt driven it would need to drive onto a dia of at least 2 feet to get a reasonable torque to accelerate the unit - this gives a belt speed of 500 ft per min - - possibly a bit high !! and how about slowing it down ?? However,the rotor would also need axial restraint which would be quite substantial. Go for end drive.
Regards CM