High Temperature In Thrust Bearing Of Steam Turbine

I'd verify that the sensors are giving you accurate readings before you go any further.

Hypothetically, for moving parts/ machine elements in motion, temperature is directly propotional to contact surface and carried load.

More moving surface in contact, the more heat it will generate. Please check installation of pads washers, consult manuals. Check bearing condition.

If all bearings are coupled on the same shaft, probably the new replaced pad bearings took the whole thrust load of the shaft until such time all the rest will be equally able to carry the thrust load.

Do you have balance drum on this turbine? What is the condition of balance drum sealing fins. Thrust bearing temperature increases with incraese in thrust of the turbine. Maximum portion of thrust is balanced by balance drum and the some thrust is left to be borned by thrust bearing so that turbine runs stably in contact with active side thrust bearing.

Please check the leak off line of balance drum which goes to LP stages. That will indicate leakage through balance drum.

The amount of heat which is gwtting generated in bearings should be removed by the circulating oil. Try to bring back the lube oil temperature to the required limit by cooling it properly at oil cooler or by putting extra water over the oil cooler.

hi,

thanks for your comment...yes we have balance drum and we think too we have problem in balance durum area...

another things...our total axial movement with thrusr bearing 0.39mm. in document vendor said axial movement can be 0.39 to 0.53mm. you see our movement is near danger area. we want to decrease the thickness of pads of thrust bearing. we want to 0.06mm increase thinkness from surface of babit. what's your idea about this soloution way?

I do not think this will help you in any way. 0.39mm is a good amount of total axial movement with bearings.

Another thing you can try by changing lube oil pressure on either side of normal pressure. Slight increase or decrease in lube oil pressure can change some lube oil flow dynamics inside the bearing due to which you can achieve some change in bearing temperatures may be on positive side to your favour. But you have to atatend balance drum sealing fins in the nearest opportunity.

GA. Also checking for scaling or chocking in cooling water tubes and cleaning it may help to reduce oil temp. But once the heat added to oil is reduced it will also reduce.

hi,,

we cleaned the cooler and replaced gaskets with new ones...but didnot change tempreture and another things...

our exchangers (coolers) type are plate exchanger.

you right..butbefore we changed pads of bearing..we increased flow and pressure of oil. i mean we have adjustable needle valve on the oli pipe before housing bearing and we opened it to increase and when we opend that the tempreture was decreased about 6 selesious but for short time...about 1 day after that the temprature was increase like previouse time...

When was the the last time that you had the temperature Readout calibrated? How do you clean your oil? Do you run a centrifuge on a continuous by-pass?Check your oil filter magnets for steel particles and your filters for blockage? If you have sight glasses on the oil connections are you getter proper flow through?

Has there been any noticeable increase in vibration while running?

Have you cleaned the water side of the lube oil coolers with a caustic or other proper cleaner? If shell and tube, have you checked the tube side for obstructions?

Back to the basics should be your first approach.