Viscosity sulfur

Yields and properties for high-severity desulfurization of Kuwait atmospheric tower bottoms are contained in Table XV. Residuum conversion to lighter products is apparent by the higher distillate yields relative to low-severity yields indicated in Table XIV. The LSFO product properties affected to the greatest extent with increasing severity are sulfur, viscosity, and pour point. 

Fig. 3.2. Molten sulfur viscosity as a function of temperature (Tuller, 1954). The viscosity minimum at 430 K and the enormous viscosity increase just above 430 K are notable.

Most polysulfides with a sulfur rank higher than three, are mixtures where the different sulfur ranks coexist in equilibrium (Table 4). In many cases elemental sulfur is also involved in the above equilibrium. Changes in temperature and pressure sometimes alter this equilibrium and precipitate sulfur. Viscosity of the polysulfides also is a function of temperature, increasing dramatically with decreasing temperature. In most cases heating polysulfides results in their decomposition to the alkyl mercaptans. Some of the aromatic polysulfides are tacky solids. Many trisulfides can be isolated as pure compounds, and exhibit unique chemical properties. They are the only polysulfides that are not corrosive to copper. 

Liquid sulfur temperature. As previously mentioned, the best temperature for sulfur spraying is approximately 310 °F. Tests have shown that as the temperature decreases, the effectiveness of the coating is reduced. Temperatures up to 317°F are acceptable but above 318°F, the sulfur viscosity is so great that good sulfur atomization is virtually impossible. 

Molten sulfur was developed into a lightweight wallboard material because it can be foamed. Just above its melting point of 115°C sulfur viscosity decreases to a minimum at approximately 160°C. Above 160°C the viscosity increases rapidly (4). To foam the sulfur at the lower part of this temperature range, additives are required which prevent the foamed structure from collapsing. Additives such as phosphorus penta-sulfide and styrene monomer have been developed by Southwest Research... 

Density — Sulfur — Mercaptans — Octane — FIONA — Chromatography — Density — Sulfur — Viscosity — Cetane — Cold properties — Aniline — Aromatics — Nitrogen — Density — Sulfur — Viscosity — Refractive Index — Cold properties — Aniline — Nitrogen — Metals — Asphaltenes — Carbon residue — Density — Sulfur — Viscosity — Carbon residue — Cold properties — Metals — Asphaltenes — Asphalt properties ... 

Molten sulfur viscosity is described in Fig. 3.2. Its key features are (i) a viscosity minimum at 160 °C and (ii) a 10,000-fold viscosity increase just above 160 °C. 

Flash point, OJ. Pour point, OJ Distillation, F Sulfur % Viscosity at 100 F max... 

With respect to fuels utilized as heating fuels for industrial furnaces, or as motor fuels for large diesel engines such as those in ships or power generation sets, the characteristics of primary importance are viscosity, sulfur content and the content of extremely heavy materials (asphaltenes) whose combustion can cause high emissions of particulates which are incompatible with antipollution legislation. 

In France there are four categories of heavy fuels whose specifications are given in Table 5.19 the different product qualities are distinguished essentially by the viscosity, equal to or less than 110 mm /s at SOT for No. 1 fuel oil, equal to or greater than 110 mm /s for No. 2 fuel oil, and by the sulfur content varying from 4 wt. % (No. 2 fuel oil) to 1 wt. % (No. 2 TBTS - very low sulfur content fuel oil). 

For the refiner, the main problem is to meet the specifications for kinematic viscosity and sulfur content. Dilution by light streams such as home-heating oil and LCO, and selection of feedstocks coming from low-sulfur crude oils give him a measure of flexibility that will nevertheless lead gradually to future restrictions, most notably the new more severe antipollution rules imposing lower limits on sulfur and nitrogen contents. 

The different cuts obtained are collected their initial and final distillation temperatures are recorded along with their weights and specific gravities. Other physical characteristics are measured for the light fractions octane number, vapor pressure, molecular weight, PONA, weight per cent sulfur, etc., and, for the heavy fractions, the aniline point, specific gravity, viscosity, sulfur content, and asphaltene content, etc. 

It is possible to calculate the properties of wider cuts given the characteristics of the smaller fractions when these properties are additive in volume, weight or moles. Only the specific gravity, vapor pressure, sulfur content, and aromatics content give this advantage. All others, such as viscosity, flash point, pour point, need to be measured. In this case it is preferable to proceed with a TBP distillation of the wider cuts that correspond with those in an actual refinery whose properties have been measured. 

Lubricating Oil Extraction. Aromatics are removed from lubricating oils to improve viscosity and chemical stabihty (see Lubrication and lubricants). The solvents used are furfural, phenol, and Hquid sulfur dioxide. The latter two solvents are undesirable owing to concerns over toxicity and the environment and most newer plants are adopting furfural processes (see Furan derivatives). A useful comparison of the various processes is available (219). 

Neste patented an industrial route to a cellulose carbamate pulp (90) which was stable enough to be shipped into rayon plants for dissolution as if it were xanthate. The carbamate solution could be spun into sulfuric acid or sodium carbonate solutions, to give fibers which when completely regenerated had similar properties to viscose rayon. When incompletely regenerated they were sufficientiy self-bonding for use in papermaking. The process was said to be cheaper than the viscose route and to have a lower environmental impact (91). It has not been commercialized, so no confirmation of its potential is yet available. 

Despite the anhydride stmcture, it is remarkably stable, surviving addition to the highly alkaline viscose, the acidic coagulating bath, and also resisting multiple laundering of the rayon fabric. The unusual stability may be attributed to the sulfur atoms, which enhance hydrophobicity, and to the stericaHy hindering neopentyl groups that retard hydrolysis. 

The products manufactured are predominantiy paraffinic, free from sulfur, nitrogen, and other impurities, and have excellent combustion properties. The very high cetane number and smoke point indicate clean-burning hydrocarbon Hquids having reduced harmful exhaust emissions. SMDS has also been proposed to produce chemical intermediates, paraffinic solvents, and extra high viscosity index (XHVI) lubeoils (see Lubrication and lubricants) (44). 

In a typical commercial dry jet-wet spinning process, PPT polymer of inherent viscosity 6.0 dL/g is added to 99.7% sulfuric acid in a water-jacketed commercial mixer in a ratio of 46 g of polymer to 100 mL of acid. The mixture is sealed in a vacuum of 68.5—76 mL of mercury. Mixing takes place for 2 h... 

The polyamides are soluble in high strength sulfuric acid or in mixtures of hexamethylphosphoramide, /V, /V- dim ethyl acetam i de and LiCl. In the latter, compHcated relationships exist between solvent composition and the temperature at which the Hquid crystal phase forms. The polyamide solutions show an abmpt decrease in viscosity which is characteristic of mesophase formation when a critical volume fraction of polymer ( ) is exceeded. The viscosity may decrease, however, in the Hquid crystal phase if the molecular ordering allows the rod-shaped entities to gHde past one another more easily despite the higher concentration. The Hquid crystal phase is optically anisotropic and the texture is nematic. The nematic texture can be transformed to a chiral nematic texture by adding chiral species as a dopant or incorporating a chiral unit in the main chain as a copolymer (30). 

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. 

Heavy fuel oil usually contains residuum that is mixed (cut back) to a specified viscosity with gas oils and fractionator bottoms. For some industrial purposes in which flames or flue gases contact the product (eg, ceramics, glass, heat treating, and open hearth furnaces), fuel oils must be blended to low sulfur specifications low sulfur residues are preferable for these fuels. 

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