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I have question about Desalter operation. I need to know which wash water is recommended for desalter, references and codes such as API, NACE....etc
I know that some refinery companies are using service water or stripped water. I asked above question because I investigate about corrosion failure for topping plant (cooler coils for mechanical seal at residue pump)
02/08/2016 A: Eric Vetters, ProCorr Consulting Services, ewvetters@yahoo.com
You generally want to avoid sources like service water. The oxygen in the water can lead to a variety of problems and hardness can lead to fouling and/or underdeposit corrosion. Stripped sour water is a common source of desalter wash water as are atmospheric and vacuum tower overhead waters. Different additives and contaminants in any of these streams can sometimes lead to problems as well. There is a NACE document Publication 34109 - "Crude Distillation Unit—Distillation Tower Overhead System Corrosion" that has a section on desalting which talks about wash water selection.
28/07/2016 A: Sridhar Balakrishnan, Bharat Oman Refineries Limited , laksrid@yahoo.com
Stripped water can be used as wash water for desalting purposes . Any refinery uses this stream for desalting purposes, general specifications to be maintained for pH, Hydrogen Sulphide, and ammonia. If the wash water contains some acid constituents, it can cause corrosion failure, like organic acids etc.
28/07/2016 A: Morgan Rodwell, Fluor Canada Limited, morgan.rodwell@fluor.com
Wash water for a desalter can be a mixture of crude column overhead water, vacuum column overhead water, stripped sour water or steam condensate/demin water. The issues around the ratios of each of these depend on the salt content of each stream, the presence of other contaminants (phenols, organic acids, cyanides). Often it is desirable to route the overhead waters back to the desalter in an attempt to get phenols to return to the oil phase (so you don't have them in the brine going to waste water treatment). However, if you have significant organic acids in these waters, it can upset the desalter chemistry, and depending on the corrosion inhibitors (amines, etc.) that are injected into the overheads may not be compatible with the desalter water chemistry. While you can sometime overcome all these issues with your treating chemical supplier, problems often arise if you need to change the wash water source on the fly. Stripped water from hydroprocessing units often makes good wash water, that from cokers or gasification units less so due to the additional species that are usually present therein. Steam condensate is clean, but it is expensive to turn purified water into brine.