Salt content

The salt content of crude oil is highly variable and results principally from production practices used in the field and, to a lesser extent, from its handling aboard the tankers bringing it to terminals. The bulk of the salt present will be dissolved in coexisting water and can be removed in desalters, but small amounts of salt may be dissolved in the crude oil itself. Salt may be derived from reservoir or formation waters or from other waters used in secondary recovery operations. Aboard tankers, ballast water of varying salinity may also be a source of salt contamination. 

Salt in crude oil may be deleterious in several ways. Even in small concentrations, salts will accumulate in stills, heaters, and exchangers, leading to fouling that requires expensive cleanup. More importantly, during flash vaporization of crude oil certain metallic salts can be hydrolyzed to hydrochloric acid according to the following reactions  

The hydrochloric acid evolved is extremely corrosive, necessitating the injection of a basic compound, such as ammonia, into the overhead lines to minimize corrosion damage. Salts and evolved acids can also contaminate both overhead and residual products, and certain metallic salts can deactivate catalysts. 

Thus knowledge of the content of salt in crude oil is important in deciding whether and to what extent the crude oil needs desalting. 

The salt content is determined by potentiometric titration in a non-aqueous solution in which the conductivity of a solution of crude oil in a polar solvent is compared with that of a series of standard salt solutions in 

The salt content is measured by ASTM D 3230 to determine the corrosiveness of a Crude oil. It is this conductivity method that measures a sample of crude oil dissolved in water and compares that to reference solutions of salt. 

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Water, Sediment, and Salt Contents in Crude Oils... 

Sodium chloride has long been used as a shale stabilizer because of low cost, wide availabiUty, and its presence in many subsurface formations. The inhibitive nature of salt muds increases as the salt content increases from seawater to saturated sodium chloride. In addition to the sodium chloride consumed aimuaHy for drilling fluid, considerable quantities are incorporated while drilling salt zones. This material has been used more for minimizing washouts in salt zones than for stabilizing shales. High salt levels have found appHcation in deep water drilling (7). 

Crude oil is recovered from the reservoir mixed with a variety of substances gases, water, and dirt (minerals) (4). Thus, refining actually commences with the production of fluids from the weU or reservoir and is followed by pretreatment operations that are appHed to the cmde oil either at the refinery or prior to transportation. Pipeline operators, for iastance, are iasistent upon the quahty of the fluids put iato the pipelines therefore, any cmde oil to be shipped by pipeline or, for that matter, by any other form of transportation must meet rigid specifications ia regard to water and salt content. In some iastances, sulfur content, nitrogen content, and viscosity may also be specified. 

Pet Foods and Commercial Animal Feeds. Eor many years, it has been known that stable, long-shelf-life, intermediate-moisture pet foods can be prepared through the use of 0.1—0.3 wt % sorbates. In these products, the antimicrobial effectiveness of sorbates is enhanced by a combination of moderate heat treatment, pH adjustment, and reduced water activity via humectants such as propylene glycol, or by adjusting sugar and salt content. These techniques have been reviewed extensively (138,139). 

Some inland municipalities now distribute water with salt content exceeding 1000 ppm, water so brackish as to be unpleasant to the taste, even though it is distributed as potable water. Each home may produce or purchase the very small requirement of freshwater for drinking and cooking. Small... 

The theory has certain practical limitations. It is useful for o/w (od-in-water) emulsions but for w/o (water-in-oil) systems DLVO theory must be appHed with extreme caution (16). The essential use of the DLVO theory for emulsion technology Hes in its abdity to relate the stabdity of an o/w emulsion to the salt content of the continuous phase. In brief, the theory says that electric double-layer repulsion will stabdize an emulsion, when the electrolyte concentration in the continuous phase is less than a certain value. 

Fig. 6-7 Rest potentials of various galvanic anodes as a function of the salt content of the medium at 20°C.

The waters through which ships travel are categorized by their salt content. The following are approximate values seawater, 3.0 to 4.0% salt coastal brackish water, 1.0 to 3.0% river brackish water, 0.5 to 1.8% salty river water, 0.05 to 0.5% river water, <0.05%. Seawater mainly contains NaCl. The salt content is approximately 1.8 times the chloride ion content. The salt content of the world s oceans is almost the same. Different salt contents can occur in more enclosed seas [e.g., the Adriatic (3.9%), Red Sea (4.1%) and the Baltic (1.0%)]. Table 17-1 gives as an example average analyses for seawater and the Rhine River. 

The salt content determines the specific electrical conductivity of the water (see Section 2.2.2). In coastal areas this varies according to tide and time of year. The following average values in ohms per centimeter serve as a guide Narvik roadstead, 33 [7] Helgoland, 27 [7] North Sea, 30 Elbe/Cuxhaven, 100 [7] Elbe/ Brunsbuttelkoog, 580 Elbe/Altona, 1200 Liibeck wharf, 75 Antwerp (Quay 271), 120 Rotterdam Botlek, 240 Tokyo Gulf, 25 [8]. 

The solubility of oxygen in water with a salt content up to 1 mol L is only dependent on the temperature. The oxygen concentrations in equilibrium with air amount to (in mg L- ) 0°C, 14 10°C, 11 20°C, 9 and 30°C, 7. The depth of water has no effect in the case of ships. In Hamburg harbor in summer, 7.3 mg L are measured in depths up to 7 m. The value can be much lower in polluted harbors and even fall to zero [8]. In the open sea, constant values are found at depths of up to 20 m. With increasing depth, the Oj content in oceans with low flow rates decreases [12] but hardly changes at all with depth in the North Sea [13]. 

The specific electrical resistance of concrete can be measured by the method described in Section 3.5. Its value depends on the water/cement value, the type of cement (blast furnace, portland cement), the cement content, additives (flue ash), additional materials (polymers), the moisture content, salt content (chloride), the temperature and the age of the concrete. Comparisons are only meaningful for the... 

In 1987 at the Weira River, four Kaplan turbines of 2.65 m diameter in two power stations were cathodically protected. The turbines were of mixed construction with high-alloy CrNi steels and nonalloyed ferrous materials with tar-EP coating. Considerable corrosion damage occurred prior to the introduction of cathodic protection, which was attributed to bimetallic corrosion and the river s high salt content of c(CT) = 0.4 to 20 g L... 

Cathodic protection of water power turbines is characterized by wide variations in protection current requirements. This is due to the operating conditions (flow velocity, water level) and in the case of the Werra River, the salt content. For this reason potential-controlled rectifiers must be used. This is also necessary to avoid overprotection and thereby damage to the coating (see Sections 5.2.1.4 and 5.2.1.5 as well as Refs. 4 and 5). Safety measures must be addressed for the reasons stated in Section 20.1.5. Notices were fixed to the turbine and the external access to the box headers which warned of the danger of explosion from hydrogen and included the regulations for the avoidance of accidents (see Ref. 4). 

Tests to simulate real-world amine plant operations have shown that caustic addition doesn t substantially improve solution corrosivity and in some cases corrosion rates increase. Maintenance of low heat stable salt anion levels is a better way to go. Concentrations as low as 250 ppm are encouraged and 5,000 to 8,000 ppm seem to be tolerable. Caustie doesn t reduce the heat stable salt content of amine solution. 

Applicability/Limitations Most t qjes of solid, liquid, and gaseous organic waste or a mixture of these wastes can be treated with this technology. Explosive wastes and wastes with high inorganic salt content and/or heavy metals require special evaluation. This operation can create high particulate emissions which require post-combustion control. 

While a desalter costs more to install than the flash drum system, it has the advantage of removing up to 95% of the salt from the oil permanently. Because less salt reaches the fractionating tower in a unit equipped with a desalter, a smaller quantity of corrosion products is formed due to high temperature breakdown and hydrolysis, and the salt content of the residual fuel oil is much lower. 

Let us consider the following case of removing an inorganic salt from an aqueous stream. It is desired to reduce the salt content of a 26 m /hr water stream (Qf) whose feed concentration, Cp, of 0.035 kmol/m (approximately 2,000 ppm). The feed osmotic pressure (rrp) is 1.57 atm. A 30 atm (Pp) booster pump is used to pressurize the feed. Sixteen hollow fiber modules are to be employed for separation. The modules are configured in parallel with the feed distributed equally among the units. The following properties are available for the HFRO modules ... 

Water hardness The hardness of a water sample due to the salt content. 

A. Khatory, F. Lequeux, F. Kern, S. J. Candau. Linear and nonlinear viscoelasticity of semidilute solutions of wormlike micelles at high-salt content. Langmuir 9 1456-1464, 1993. 

Controlling for these forces requires variation in the amount of salt, organic solvent, and the pFI of the mobile phase. It is impractical to perform such experiments with 50 mM formic acid an alternative additive must be used that maintains its chaotropic properties independent of salt content or pFI. Fortunately, mobile phases containing 50 mM hexafluoro-2-propanol (HFIP) afford a fractionation range comparable to that of the formic acid (Fig. 8.6), permitting the effects of these variables to be studied systematically. 

Salz-garten, m. salt garden, -gehalt, m. salt content. 

Theoretical concepts for generating electricity from ocean currents such, as the Gulf Stream, and salinity gradients (differences in salt content) are being investigated. More research and development is required before these concepts reach the stage of demonstration power plants. 

A standard procedure for estimating the salt content of oil-base muds consists of the following steps [26] ... 

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