Study of Desalting Process of Crude Oil in Refineries

The process of desalting takes into account a water-washing operation which is performed at the beginning of the production phase in the field and after which is done at the refinery site for some additional crude oil cleanup. The crude oil that is mostly found in the refineries is composed of fine saline water droplets, crystals of salt, suspended solids and also some metal traces. When there is a significant amount of dissolved salts in the crude oil, it can negatively impact the crude refining process. In such scenarios, even the best desalter bushings may not effective.

For example, the foul heat exchangers can obstruct pipe lines and thus affects the performance of other refinery tools and machineries. To deal with salts-related issues, it is imperative to remove the salt from the crude oil. This will certainly eliminate corrosion, plugging, and fouling of the tools used in the refinery process. You can often find electrical desalting plants set up within the crude oil production systems.

Dealing with crude oil is not an easy task, since it consists of complicated mixtures obtained from various parts of the planet, and also most of the crude consist of dilute (dispersion or emulsion) of superfine water droplets. These contain a range of salts, solids and metal particles. There are chances that these emulsions are stable thanks to the presence of naturally produced surfactants in oil. Some of these surfactants include: asphaltenes, naphthenic acids, resins and fine solid particles. Unfavorable effects of these impurities may cause the unit run lengths to become short and reduce the reliability of the equipment. To deal with corrosion and fouling of machineries/tools, electrical desalting plants are mostly setup in crude oil production units. This takes away the water-soluble salts from the oil stream. People who work at the refiners generally wash the crude oil with fresh water, and then chemicals (demulsified) are added to it.

Because emulsions can form in the process, there comes a risk of water carryover to solve the problem when a chemical demulsifier is mixed to encourage the breaking down of the emulsion. When this technique is implemented at a refinery site, an electric field is applied across the settling vessel. This is done so as to coalesce the polar salty droplets of water, and, thereby, reducing the water and salt content. A proper understanding of the numerous variables that impact the desalting process is necessary, particularly the impact of chemical demulsifiers being utilized. This can also optimize operational costs.

Author: The author is a blogger and the article is about desalter process for crude oil.

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desalters Joined: December 23rd, 2018