problem with thrust bearing on turbine
problem with thrust bearing on turbine
(OP)
This bearing is a thrust bearing on a horizontal hydro unit, francis turbine the firm is Voith hydro, this bearing is composed by an axial bearing that support the force of the turbine on their way of aspiration, an other axial bearing that suport the rejection of load effect and a radial bearing that support the radial forces of the turbine and a flywheel that is mounted between generator and bearing. This bearing fail last year with all the antifriction of the axial bearing that support the force of the shaft in the aspiration way, the bearing is totally destroyed, after that we take the spare ones and change with no checkings cause a lot of money was losing, but in august on last year, 4 months after this we dismount the bearing and find a fault on the spare one... i´ll attach the pics from the reports, cause i have no pics other than on the reports. sorry it´s on spanish the text





RE: problem with thrust bearing on turbine
I have some questions like, what kind of antifriction mixture it´s usual to use on similar applications? what´s is the usual temperature of welding the babbit and the support metal? is this
RE: problem with thrust bearing on turbine
RE: problem with thrust bearing on turbine
Are you sure this bearing is getting adequate lubrication. Do you have lube oil temperatures in and out of the bearing?
rmw
RE: problem with thrust bearing on turbine
Can you take that report and retype it in a program that has a language translator? Afterwards you'll have to clean up the English because of all the technical terms, but I think you will get more help on this forum if that document can be translated since this is bassically an english speaking forum.
rmw
RE: problem with thrust bearing on turbine
in anyway, thanks a lot for your attention.
RE: problem with thrust bearing on turbine
RE: problem with thrust bearing on turbine
it seems to me there is a combination of two factors in causing the bearing failure:
- unadequate oil circulation inside the bearing, and specifically in the axial thrust part. In fact, this bearing is normally not designed to carry load on the antifriction material directly, at least not in "regime" conditions (only in the very first phases of startup and in the very last phases of coastdown); the oilfilm between antifriction and steel ring thrust surface should carry the load. If there is unproper circulation, the oilfilm can tear and break, causing the metal parts to contact. Other cause can be strong axial vibrations which will cause oilfilm instability and tearing, but sincerely I find it difficult if the turbine is operated properly
- turbine not operated properly, i.e. outside of the guaranteed range, causing out-of-design axial thrust, and/or abnormal vibrations due to flow instability / cavitation. Also included in this "cause", is the possibility that the air injection device (if there is one), used to stabilize flow at partial loads, is out of order. Even more likely, the "upper" cover labyrinth seals may be unacceptably wornout, causing a strong increase of the axial thrust which will cause an out-of-design operation of the bearing; or, the balance piping system may have some element out-of-order, causing the pressure on the back of the runner's crown to increase (and thus the axial thrust to increase).
I'd check, first of all, the records of the bearings temperatures (as it seems you already have some ideas about the vibrational behaviour of the bearing), then check the status of the runner's labyrinths and of the balance piping system. This may not be possible without the co-operation of a turbine specialist, though.
Regards
RE: problem with thrust bearing on turbine