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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

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