Reactive Adjunct – New Technology in Desalting Chemistry
Dorf Ketal has invented a new class of desalter chemistry called “reactive adjunct chemistry” that offers step change improvements in desalting efficiency and amine removal. For refiners that are desalting limited in selection of economically advantaged crudes or who are considering capital investment to expand desalting capacity, this new technology offers a low cost way of expanding desalting capacity and reducing risk of overhead corrosion problems caused by the presence of tramp amines.
The emulsion breaker (EB) is the heart of the desalter chemistry program. Adjunct chemistry refers to the use of a secondary chemistry to supplement the primary EB. Traditionally the classes of adjunct chemistries are 1) solids wetting, 2) reverse emulsion breaker, and 3) acid.
Reactive adjunct chemistry is a new fourth category of adjunct desalter chemistry, based on aldehyde chemistry. Aldehydes are known to react with amines, ammonia, metals, and H2S in the crude, forming products of reaction that are easier to remove from the crude. More efficient removal of crude contaminants leads to shorter time for resolving emulsions and better crude dehydration. Faster water removal adds desalting capacity that can be used to increase crude flexibility, reduce salt in the crude, water in the oil, chemical costs, and a combination of the above. The value of this new chemistry to improve desalting can be measured by reduced overhead corrosion, crude costs, caustic usage, oil under-carry, or an avoidance of capital expansion. Reactive adjunct chemistry is not an acid, it is a formulation of water soluble hydrocarbons that are safe to feed and easily handled in the waste water system.
The Desalter Efficiency Strategy uses low dosages of the chemistry to improve desalter efficiency. It is designed to deliver improved desalter performance beyond that which can be obtained by the primary emulsion breaker alone, but does not use a high enough chemical dosage for amine removal. The additional cost of the chemistry is in the range of tenths of a cent per barrel treated. In this approach, the reactive adjunct chemistry improves the rate of emulsion resolution, improving the dehydration of the oil and the salt and solids removal efficiencies. With a tighter oil/water interface, the brine quality is dramatically improved, resulting in a reduction in slop oil generation and its associated reprocessing costs.
The Amine Removal Strategy uses higher dosages of the reactive adjunct chemistry and is designed to reduce the levels of tramp amines coming in with the crude and desalter wash water. By removing these amines in the desalter, there is an associated reduction in the potential for amine chloride salt deposition in the crude tower overhead, as indicated by the lower amine salt point temperatures. The incremental cost of the tramp amine strategy is in the range of 1 to 3 cents per barrel.
The Crude-Flex Strategy of using the reactive adjunct is a no cost option for increasing the ability of the refiner to make faster decisions on purchasing opportunity crudes or to respond more effectively to the occasional upset in desalter operation. In this strategy, the reactive adjunct is used to reduce EB dosage, and reduced consumption of the emulsion breaker pays for the cost of the reactive adjunct. It utilizes the powerful synergy of the two chemistries to be better prepared for crude flexibility needs and/or upsets.
This strategy is for the refiner with sporadic needs for improved desalting performance and/or tramp amine removal and for those situations where there is a concern that running opportunity crudes will cause desalting problems. Improved desalting may be needed in response to unexpected issues encountered when processing a new opportunity crude, routine challenges with slop reprocessing or other operational issues that result in excessive oil under-carry. And tramp amine removal can be necessitated by the processing of amine-contaminated crudes and slops, as well as, from amine and ammonia excursions in the desalter wash water sources.