Transformer Oil Reconditioning and Reclamation 1

[isnata]

Hello,

Has anyone here had experience with deciding whether to recondition (reclaim) used transformer oil or to junk it (sell it as used oil)? We performed oil quality test on the oil and they all fell under class 2 per IEEE C57.106-2006. The recommendation given for class 2 oil is to recondition using filter pressing or vacuum dehydration.

I researched the economics of buying a vacuum dehydrator to recondition the oil, and then retesting them to check whether they meet the oil quality we wanted. So far, selling the oil as used oil might be a better option.

I would like to know the practices used by other utilities.

What do you usually do with used transformer oil?

 

[DTR2011]

You have not mentioned how much oil you are dealing with. I would say that for less than ~100 US gallons, it may be cheaper to replace the oil. Don't expect much for selling the used oil, other than not having to deal with it.

You may consider hiring a service company to process the oil. As an example, my company owns a large (semi truck mounted) oil processing
rig that we use to both process new transformer oil, or recondition existing oil - this is cost effective on large transformers (1000's of US gallons). These types of oil processing rigs also have the ability to pull and hold a vacuum on the transformer, as well as vacuum fill. Most modern oil processing rigs also have sophisticated process monitoring equipment on board to check for moisture content and dew point during their operation.

For smaller jobs we have filter presses (LTC's or pad mount transformers). In both cases, we are generally able to return oil to minimum or above specifications.

If you haven't done it already, anyone who will touch your oil with their equipment will require a PCB sample.

 

[isnata]

Hi DTR2011,

It's good to hear your team has a full set up performing this type of reconditioning. The oil I'm talking about have been tested for PCB level, and they all passed the level required in Canada.

What is the equipment you use to process the oil? Our oil is in the 1000's of US gallons.

 

[stevenal]

Wet oil means you have wet paper. Replace the oil, and the new oil will gradually pull moisture from the paper until it too is wet. Consider doing an on-line reconditioning that circulates the oil so that moisture is pulled from the paper during the process.

 

[isnata]

What do you mean Stevenal

 

[davidbeach]

If you dry the oil outside the transformer you still leave the moisture in the paper. If you use a process that circulates the oil through the transformer as the oil is being tried it pulls the moisture out of the paper as the oil moisture content goes down.

 

[bacon4life]

Is this oil you have sitting around as spare? Or is inside a piece of energized equipment?

We have a semi-truck size mobile oil processor that can do both vacuum and fullers earth processing. We reuse oil from transformers, as well as very dirty oil from LTCs and oil circuit breakers.

The catalytic crack methods used to refine oil has changed, resulting slightly less stable oil than decades ago. Old properly reclaimed oil may be preferable to brand new oil.

 

[prc]

Reconditioning and reclaiming are not same. If the oil breakdown voltage and water content are high,( but other parameters like IFT, power factor are within limits) you can recondition oil by filtering out particles and removing moisture in a vacuum filter machine. But if acidity, IFT and power factor are outside permissible limits, reconditioning will not improve the condition.Then you have to go for reclamation where hot oil is sent through a bed of Fuller's earth.Then all polar compounds from ageing of oil are removed by the bed.Synthetic oxidation inhibitors are added to oil after the above processing. Portable reconditioning and reclaiming units are available.

 

[isnata]

Davidbeach, the oil were previously used in substation power transformers and are now in barrels.

Bacon4life can you please share a link of the setup you have to perform the reconditioning and reclaiming?

Prc can you please give examples of the portable equipment that you mentioned?

Thanks.

 

[prc]

It is not clear to me why you drained the oil. Since it is in class condition 2 only, simple reconditioning by filtering plus vacuum hydration is sufficient. Better to contact contractors who will do this work using portable filter machines.

 

[stevenal]

How was I not clear? Wet oil does not exist in isolation, the moisture moves back and forth from oil to the paper part of your transformer's insulation system, based on temperature and saturation levels. Put nice dry oil in a wet transformer and you will have a slightly less wet transformer. The alternative is to perform an on-line processing. Oil is circulated through equipment that dries it, and the dry oil is circulated back through the transformer where it can draw more moisture from the paper. TDS

 

[bacon4life]

Our processor is a couple of decades old, so I don't have details of the setup handy.

Google has lots of examples of mobile processors such as

http://www.aliexpress.com/item/Mobi...75403024.html?spm=2114.40010508.4.110.uJI0pH.

Our processor seems to require a far amount of maintenance, so be sure to look for a vendor with local support.