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SULFUR PLANT, AND CRUDE BLENDING, TREATING, AND DESALTING
Publication date:1Q 2015
Sulfur Plant, and Crude Blending, Treating, and Desalting
The need for on-purpose sulfur production has become non-existent, as byproduct sulfur production from refineries and upstream oil and gas production sites more than meets the current demand for sulfur in the market. Further, major new supplies of byproduct sulfur are expected to be introduced in to market over the coming years due to tightening product specifications for transportation fuels, developing sour gas fields in the Middle East, and increasing oilsands production in Canada.
Typically, refinery sulfur plants consist of an acid gas removal unit, a Claus sulfur recovery unit, a tailgas treatment unit (to achieve sulfur recovery levels >99.99%), and, in some instances, sulfur degasification and finishing processes The amount of sulfur produced by each refinery will differ based on a number of factors including sulfur content in the feed coupled with the final product slate and final product specifications. This section of the Review will focus on the recovery of sulfur in a refinery setting; specifically omitted from the discussion is sulfur recovery technologies that are focused on upstream applications, such as oil and gas production.
Continued sulfur plant technology developments have focused on improving the energy efficiency of the acid gas removal unit, Claus unit, and tailgas treatment unit in order to lower operating costs as sulfur removal is done at a cost to the refiner and offers little back in terms of value, so minimizing costs is necessary to improve margins. Additionally, the utilization of Claus plants that can recover sulfur while mitigating the effects of high levels of ammonia and BTX was also discussed as deeper levels of HDS needed to meet more stringent gasoline sulfur requirements tend to increase ammonia production. Also, the use of trilobe and quadralobe tailgas treating catalysts for reducing the pressure drop across the tailgas treater in order to lower coke make on the catalyst has been commercialized by a number of catalyst companies. Finally, processes that can produce sulfuric acid from recovered sulfur may become more popular due to the expected sulfur glut that will occur over the coming years. The sulfur plant section also features the latest trends and technology offerings, including:
Crude Blending, Treating, and Desalting
With the consistent changes to the crude supply being processed across the globe, refiners are facing new challenges to ensure the safe and reliable operation of their entire facility. Crudes that are considered opportunistic due to their low cost are highly desired for refiners, but without proper treatment these crudes can severely damage downstream units and equipment. Furthermore, with the large variety of crude available, refiners are seeking the ideal blends of various crudes to economically optimize their refineries while resisting solid and salt accumulation, corrosion and fouling to essential equipment (due mainly to acidic compounds and asphaltene deposition). Whether it is heavy, high TAN crudes or blends of various crude sources, these feedstocks require treatment prior to reaching the CDU to keep operations smooth throughout processing. This is where pretreatment methods such as desalting and the use of chemical additives play a major role.
Preparing crude for the CDU mainly involves electrostatic desalting, which removes water and water-soluble salts. This process is also supported by additional techniques including the upstream removal of hydrogen sulfide by the addition of so-called "H2S scavengers," metal-removal additives, asphaltene dispersants, base addition to reduce naphthenic acid content of high-acid crudes (HACs), solids filtration, and chemical demulsifiers. Improved crude blending operations upstream of the desalter may help alleviate some of the difficulties associated with these preparation steps, and at the very least, a more thorough understanding of the crude feedstock slate will be beneficial for optimizing crude treating and desalting activities.
The ability to predict crude blend properties has proven to be the most efficient means of preventing damage to refining equipment, as refiners can determine which ratios offer the ideal properties for their refinery, or they can optimize the crude pretreatment process to combat the expected issues. This involves the use of both software-related solutions and testing/analysis of crude samples. Both approaches have seen new developments in recent years, and can be used together to optimize a blend for a particular refinery. There are a growing number of chemical products available to assist refiners with overcoming desalting problems. Chemical companies market a range of emulsion breakers tailored for desalter operations as well as extensive chemical treatment packages to aid in metals removal; inhibit corrosion, fouling, and scaling; prevent foaming; and remove sulfur. A number of chemical companies also provide reverse emulsion breakers to treat oily brine effluent upstream of the wastewater treatment plant. Corrosion control technologies that include monitoring and predictive technique are also available to be used when processing high-acid crudes. The crude blending, treating, and desalting also features the latest trends and technology offerings, including:
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SRU, acid gas removal, AGR, Claus unit, tailgas treating, TGT, SOX, desulfurization, CO2, COS, clean fuels specification, H2S, ultra-low sulfur, ULSD, ULSG, clean fuels, elemental sulfur, direct oxidation, amine scrubbing, amine solvent, advanced process control, acid gas corrosion, foaming, amine loss, fuel gas sweetening, ammonia destruction, BTX destruction, sour crude, sub dew-point Claus, oxygen-enriched Claus, sulfur degasification, sulfur finishing, sulfur granulation, analyzers, instrumentation
crude, crude distillation, opportunity crudes, tight oil, oilsands, dumbbell crudes, heavy crude, extra-heavy crude, high-acid crude, crude blending, crude treating, desalter, desalting, electrostatic desalting, incompatibility, TAN, API gravity, asphaltenes, asphaltenes precipitation, CDU, ADU, H2S scavengers, static mixers, sonic energy, additives, mercaptans, naphthenic acid, wastewater, emulsion breakers, demulsifier, stability, brine effluent treating, corrosion, water wash, metals removal, neutralizer, viscosity