Desalting and Dewatering

Petroleum is recovered from the reservoir mixed with a variety of substances gases, water, and dirt (minerals) (Burris and McKinney, 1992). Thus, refining actually commences with the production of fluids from the well or reservoir and is followed by pretreatment operations that are applied to the crude oil either at the refinery or prior to transportation. Pipeline operators, for instance, are insistent upon the quality of the fluids put into the pipelines therefore, any crude oil to be shipped by pipeline or, for that matter, by any other form of transportation must meet rigid specifications in regard to water and salt content. In some instances, sulfur content, nitrogen content, and viscosity may also be specified. 

Desalting is a water-washing operation performed at the production field and at the refinery site for additional crude oil cleanup (Fig. 13.2). If the petroleum from the separators contains water and dirt, water washing can remove much of the water-soluble minerals and entrained solids. If these crude oil contaminants are not removed, they can cause operating problems during refinery processing, such as equipment plugging and corrosion as well as catalyst deactivation. 

The usual practice is to blend crude oils of similar characteristics, although fluctuations in the properties of the individual crude oils may cause significant variations in the properties of the blend over a period of time. Blending several crude oils prior to refining can eliminate the frequent need to change the processing conditions that may be required to process each of the crude oils individually. 

However, simplification of the refining procedure is not always the end result. Incompatibility of different crude oils, which can occur if, for example, a paraffinic crude oil is blended with a heavy asphaltic oil, can cause sediment formation in the unrefined feedstock or in the products, thereby complicating the refinery process (Mushrush and Speight, 1995). 

After petroleum recovery and prior to the commencement of refining, there needs to be an estimate of the potential behavior of petroleum during refining operations. Briefly, three frequently specified properties that are used to evaluate petroleum are density (specific gravity, API gravity), characterization factor, and sulfur content (Matar, 1992 Speight, 1999 2000 2001). 

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Descriptions are provided for (1) desalting and dewatering (2) separation processes, of which distillation is the prime example (3) conversion processes, of which coking and catalytic cracking are prime examples and (4) finishing processes, of which hydrotreating to remove sulfur is a prime example. Descriptions of the various petroleum products (from fuel gas to asphalt and coke) sire also given. 

The desalting process is mostly driven by thermodynamic and hydrodynamic constraints. For the purpose of modeling the crude distillation unit, we consider the desalting operation as a simple component splitter that removes any water present in the feed crude. Desalting and dewatering processes are very effective and do not consume significant resources compared to other units, so this simple model representation is justified. 

The crude oils should be desalted and dewatered before refining because salts produce enormous corrosion problems, they are poison for the catalysts in refining and reduce the efficiency of energy exchanging, and increase the oilflow resistance and even obstruct the pip>es. 

The most extensive work on intelligent polymers has been carried out on stimuli-responsive hydrogels, particularly those based on pH-sensitive and thermally-sensitive monomers. Their most important applications are related to desalting and/or dewatering of protein solutions, delivery of drugs, on-off immobilised enzyme reaetors, microrobotics and artificial muscle. 

These requirements and other reasons make the preparation of petroleum before processing very necessary. Petroleum preparation includes drying (removal of water or dewatering) and desalting of petroleum, and complete or partial removal of dissolved gas. 

Loginov V. 1., Dewatering and desalting of oil. Chemistry, Moscow, 1979 (in Russian). 

Over the years a number of techniques and approaches have proved to be useful tools to successfully isolate low-level impiu ities and degradants. TLC is most useful when an impurity or degradant is identifiable by LC-MS and above the 1% level. In cases, where NMR analysis is essential for identification, semipreparative SFC, semipreparative HPLC, and flash chromatography are more suitable techniques. Please refer to the Handbook of Pharmaceutical Analysis, 1st ed. for a more in-depth explanation of TLC and flash chromatography s use for impurity isolation. As mentioned earlier, SPE and liquid-liquid extractions are at times incorporated into the process. These tools can quickly convert bulk supply materials into a more suitable form for SFC or HPLC injection. SPE is also a useful tool in dewatering and desalting final RP-HPLC isolated materials obtained from solvents containing mobile-phase additives. 

Uses Demulsifier used as component of dewatering and desalting formulations in oil and related industries Features Destabilizes w/o emulsions... 

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