Processing, lubricating oil

V.I. of raw. lube stocks (see Table 4-1). By solvent extraction processes, lubricating oils of Viscosity Index higher than 100 can be produced. Figures 4-1 and 4-2 indicate the relationship between Viscosity Index and Saybolt Universtd viscosity at 100 and 210 F. The Viscosity Index tabulations of the ASTM (D567) must be employed (rather than Fig. 4-2) for accuracy. 

Urea has the remarkable property of forming crystalline complexes or adducts with straight-chain organic compounds. These crystalline complexes consist of a hoUow channel, formed by the crystallized urea molecules, in which the hydrocarbon is completely occluded. Such compounds are known as clathrates. The type of hydrocarbon occluded, on the basis of its chain length, is determined by the temperature at which the clathrate is formed. This property of urea clathrates is widely used in the petroleum-refining industry for the production of jet aviation fuels (see Aviation and other gas-TURBINE fuels) and for dewaxing of lubricant oils (see also Petroleum, refinery processes). The clathrates are broken down by simply dissolving urea in water or in alcohol. 

Lubricants, Fuels, and Petroleum. The adipate and azelate diesters of through alcohols, as weU as those of tridecyl alcohol, are used as synthetic lubricants, hydrauHc fluids, and brake fluids. Phosphate esters are utilized as industrial and aviation functional fluids and to a smaH extent as additives in other lubricants. A number of alcohols, particularly the Cg materials, are employed to produce zinc dialkyldithiophosphates as lubricant antiwear additives. A smaH amount is used to make viscosity index improvers for lubricating oils. 2-Ethylhexyl nitrate [24247-96-7] serves as a cetane improver for diesel fuels and hexanol is used as an additive to fuel oil or other fuels (57). Various enhanced oil recovery processes utilize formulations containing hexanol or heptanol to displace oil from underground reservoirs (58) the alcohols and derivatives are also used as defoamers in oil production. 

Petroleum and Petrochemical Processes. The first large-scale appHcation of extraction was the removal of aromatics from kerosene [8008-20-6J to improve its burning properties. Jet fuel kerosene and lubricating oil, which requite alow aromatics content (see Aviation and OTHER gas... 

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). 

The low molecular weight materials produced by this process are used as lubricants, whereas the high molecular weight materials, the polyisobutylenes, are used as VI improvers and thickeners. Polybutenes that are used as lubricating oils have viscosity indexes of 70—110, fair lubricating properties, and can be manufactured to have excellent dielectric properties. Above their decomposition temperature (ca 288°C) the products decompose completely to gaseous materials. 

With the beginning of the industrial revolution around 1800, oil became increasingly important for lubrication and better illumination. Expensive vegetable oils were replaced by sperm whale oil [8002-24-2], which soon became scarce and its price skyrocketed. In 1850 lubrication oil was extracted from coal and oil shale (qv) in England, and ultimately about 130 plants in Great Britain and 64 plants in Pennsylvania, West Virginia, and Kentucky employed this process. 

Lubricants. Petroleum lubricants continue to be the mainstay for automotive, industrial, and process lubricants. Synthetic oils are used extensively in industry and for jet engines they, of course, are made from hydrocarbons. Since the viscosity index (a measure of the viscosity behavior of a lubricant with change in temperature) of lube oil fractions from different cmdes may vary from +140 to as low as —300, additional refining steps are needed. To improve the viscosity index (VI), lube oil fractions are subjected to solvent extraction, solvent dewaxing, solvent deasphalting, and hydrogenation. Furthermore, automotive lube oils typically contain about 12—14% additives. These additives maybe oxidation inhibitors to prevent formation of gum and varnish, corrosion inhibitors, or detergent dispersants, and viscosity index improvers. The United States consumption of lubricants is shown in Table 7. 

Lubricating oils are also used in industrial and process appHcations such as hydrauhc and turbine oils, machine oil and grease, marine and railroad diesel, and metalworking oils. Process oils are used in the manufacture of mbber, textiles, leather, and electrical goods. The distribution of lube oils used in these apphcations in 1992 is as follows automotive, 45711 industrial, 2229 t and process, 1070 t (- SIS, 000 gal) (11). 

As is indicated in Figure 4, saturates contribute less to the vacuum gas oil (VGO) than the aromatics, but more than the polars present at percentage, rather than trace, levels. VGO itself is occasionally used as a heating oil but most commonly it is processed by catalytic cracking to produce naphtha or by extraction to yield lubricant oils. 

The early developments of solvent processing were concerned with the lubricating oil end of the cmde. Solvent extraction processes are appHed to many usefiil separations in the purification of gasoline, kerosene, diesel fuel, and other oils. In addition, solvent extraction can replace fractionation in many separation processes in the refinery. For example, propane deasphalting (Fig. 7) has replaced, to some extent, vacuum distillation as a means of removing asphalt from reduced cmde oils. 

Dialkyl and diaryl dithiophosphoric acids are the bases of many high pressure lubricants, oil additives (see Lubrication and lubricants), and ore flotation chemicals (see Mineral recovery and processing). Organophosphoms insecticides such as Parathion are made by chlorination of the appropriate diaLkyl dithiophosphate and subsequent reaction of the intermediate dialkyl thiophosphoric chloride with sodium -nitrophenolate according to the following (see... 

Orifice. Orifice viscometers, also called efflux or cup viscometers, are commonly used to measure and control flow properties in the manufacture, processing, and appHcation of inks, paints, adhesives, and lubricating oils. Their design answered the need for simple, easy-to-operate viscometers in areas where precision and accuracy are not particularly important. In these situations knowledge of a tme viscosity is uimecessary, and the efflux time of a fixed volume of Hquid is a sufficient indication of the fluidity of the material. Examples of orifice viscometers include the Ford, Zahn, and Shell cups used for paints and inks and the Saybolt Universal and Furol instmments used for oils (Table 5). 

Sedimentation equipment can be divided into batch-operated settling tanks and continuously operated thickeners or clarifiers. The operation of the former is simple. Whereas use has diminished, these are employed when small quantities of Hquids are to be treated, for example in the cleaning and reclamation of lubricating oil (see Recycling, oil). Most sedimentation processes are operated in continuous units. 

The octylphenol condensate is used as an additive to lubricating oils and surface-active agents. Other uses of dimer are amination to octylamine and octyldiphenylamine, used in mbber processing hydroformylation to nonyl alcohol for phthalate production and carboxylation via Koch synthesis to yield acids in formulating paint driers (see Drying). 

Methods of Liquefaction and Solidification. Carbon dioxide may be Hquefted at any temperature between its triple poiat (216.6 K) and its critical poiat (304 K) by compressing it to the corresponding Hquefaction pressure, and removing the heat of condensation. There are two Hquefaction processes. In the first, the carbon dioxide is Hquefted near the critical temperature water is used for cooling. This process requires compression of the carbon dioxide gas to pressures of about 7600 kPa (75 atm). The gas from the final compression stage is cooled to about 305 K and then filtered to remove water and entrained lubricating oil. The filtered carbon dioxide gas is then Hquefted ia a water-cooled condenser. 

In selec ting the machines of choice, the use of specific speed and diameter best describe the flow. Figure 10-67 shows the characteristics of the three types of compressors. Other considerations in chemical plant service such as problems with gases which may be corrosive or have abrasive solids in suspension must be dealt with. Gases at elevated temperatures may create a potential explosion hazard, while air at the same temperatures may be handled qmte normally minute amounts of lubricating oil or water may contaminate the process gas and so may not be permissible, and for continuous-process use, a high degree of equipment rehability is required, since frequent shutdowns for inspec tion or maintenance cannot be tolerated. 

An effective auxiliaiy device frequently used with packing and rotary shafts is the seal cage (or lantern ring), shown in Fig. 10-110. The seal cage provides an annulus around the shaft for the introduction of a lubricant, oil, grease, etc. The seal cage is also used to introduce liquid for cooling, to prevent the entrance of atmospheric air, or to prevent the infiltration of abrasives from the process liqmd. 

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