Turbine Lube Oil Moisture and Dust Removal

[Yomahuta]

I am a fresh engineer at a thermal power plant and there is an ongoing issue with the turbine lube oil being dusty and moist nowadays here. There are two machines interchangeably being used for turbine lube oil tank. One is paper filtration-based machine using filter papers to remove the contaminants based on paper micron size etc. The other is moisture separation machine using centrifuging of oil to remove moisture, but the problem persists and becomes serious based on the duty hours of these machines. The engineer proposes the operation hours of these machines based on the NAS 1638 based test and the moisture PPM based tests. Where shall I be thinking around to propose a solution?

 

[TugboatEng]

The centrifuge should be able to separate dirt and water. What temperature is the oil at the centrifuge inlet?

 

[Yomahuta]

The temperature at inlet of centrifuge is around 50 degrees. The machine has a built-in heater which trips at 52 deg C.

 

[georgeverghese]

If the turbine oil is getting contaminated with dust and dirt and moisture, then the shaft oil separation barriers at the turbine shaft seals are most probably not working properly.

 

[TugboatEng]

I meant to look up some charts relating oil viscosity to centrifuge throughput. Your centrifuge should be highly effective at removing water and particles even with a single pass. If the viscosity is too high/temperature too low this will reduce your capacity. Detergent oils that are have a higher affinity for water will also reduce throughput.

Of course, all of this is assuming the centrifuge is in good condition with the proper gravity ring.

Your paper filtration should only exist as a backup.

 

[Yomahuta]

Guys.

We're not using the centrifugal machine now. There's two machines used interchangeably. Plate-frame type filter papers based machine (

https://images.app.goo.gl/KvJP8mRCDE2eJ23W7)

and a vacuum oil purifier (

https://www.cqpuretech.com/Vacuum-Turbine-Oil-Filtration-Machine-p.html).

Anyone having idea what does the electric heater do? Like it trips at a set value but isn't approaching that value. Similarly the NAS Class is also increasing.


One thing someone said about gland seal, can anyone explain in detail?

The problem still persists.

 

[FacEngrPE]

Cold hydraulic oil is more viscous than hot oil, so it is harder to push cold viscous oil through filters than hot oil. It is also easier to evaporate water from hot oil than cold. If your oil is too cold, it may limit your filter throughput (flowrate) to a value which prevents your filter from removing material from the oil faster than it accumulates. (Tug makes this same point with fewer words).

You should find the source of the dirt entry and fix that.