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We have a problem in our Desalter. When we turn on the electric transformers, the electricity feeder trips off immediately several times. One of the transformers is damaged. The desalter contains only Crude Oil (Not mixed with water) What are the causes?

Mar-2023

Answers

sam lordo, Becht, salordo@comcast.net

Some of this has already been covered in other answers, but the one that make the most sense is that you are getting slugs of water with the incoming crude (test the raw crude using the BS&W test and look for free water. Try starting the desalter up with a lower level (if this a low velocity type).

May-2023
Dave Hart, Electrostatic Services Company, Inc., dehart@esscoinc.us

Please characterize how "...one of the transformers is damaged...". Simply by extension of main breaker tripping when closed? Or by some other independent means? The issue is most likely due to a weak, maladjusted or improperly spec'd main breaker. Or possibly a failed reactor coil that's designed to limit full load current to a value less than breaker rating.

Apr-2023
Melanie Yackel, NEET Process, Melanie@neetprocess.com

If the transformer(s) are traditional AC transformers (not dual frequency or EDD) they should be 100% reactant or 100% self-limiting design. This means that under Imax all transformers shorted at the same time should not trip the breaker per design. This fact disqualifies the solutions presented in the other two answers you’ve received online.

Please verify that the installed transformer(s) are 100% reactant on the nameplate or tag.

As the feeder is tripping it may be 1) a bad breaker or 2) short in the low voltage feed going to transformer(s) or 3) failed reactor or coil. I would be happy to help you troubleshoot this further via email or zoom.

Mar-2023
Melanie Yackel, NEET Process, Melanie@neetprocess.com

If the transformer(s) are traditional AC transformers (not dual frequency or EDD) they should be 100% reactant or 100% self-limiting design. This means that under Imax all transformers shorted at the same time should not trip the breaker per design. This fact disqualifies the solutions presented in the other two answers you’ve received online.

Please verify that the installed transformer(s) are 100% reactant on the nameplate or tag.

Mar-2023
Jonathan Boul, Neet, jonathan@neet-desalters.com

If the feeder is tripping, it sounds like 1) a bad breaker or, 2) short in a feed voltage conductor going to the transformer or, 3) damage to the transformer itself such that it is no longer self-limiting.

This assesment assumes your transformer is designed for 100% impedance or reactance (e.g. self-limiting) as can be verified on its tag or nameplate.

Mar-2023
Francisco DURAN, OILCALS REP, francis.duran@rep.fr

You would need to run a intro-inspection of the vessel to check the integrity of electric grids and isolation support for any evidence of dammage cracks, corrosion, etc.

Mar-2023
N Sekar Murthy, Ashphil Consultancy, nssvdvr@gmail.com

Couple of points - may be of help to trouble shoot.
1. In the desalter where the crude gets introduced? Is it between grids or below grids.. If crude has tighter emulsion already then, the introduction of crude between grids can pose such issue.
2. Some crudes have higher conductivity. Checking the quality specially the type of metal porphyrins could add to such concern.
3. Worth derating the secondary voltage to say 16 KV or lower. Some refiners install KAR (Kick Amp responder) ahead of step-up transformer. Use of KAR will help to modulate secondary voltage and prevent spurious trips.
4. Check any mechanical detachment in grid placement.

Mar-2023
Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

Firstly, you need to check that the BSW of the Crude Oil is according to the design parameter of the desalting system as well as the interface level is adequate to avoid the risk of grounding the desalter leading to the trip of the power electric systems.

It's important to analyze if the desalting system suffered some instability event which caused internal damages to desalters like the electrodes breaking, for this it's necessary open the desalters and access the internals of the equipment. I suggest to start by the desalter that have a failed transformer. Furthermore, it's important to check the isolation of the electrode responsible for the electric alimentation of the desalter internals from the transformers, a failure in the electric insulation can cause the trip of the electric system.

Mar-2023
Marcio Wagner da Silva, Petrobras, marciows@petrobras.com.br

This can be caused by internal damages to desalting systems which can led to contact between shell of the desalter and the electrodes.

It's important to analyze if the desalting system suffered some instability event which caused internal damages to desalters like the electrodes breaking, for this it's necessary open the desalters and access the internals of the equipment. I suggest to start by the desalter that have a failed transformer.

Another important point is to check the isolators integrity of the transformers which are responsible to conduct the electricity to the desalters internals.

Mar-2023