Solvent refining processes deasphalting

The major solvent refining processes include solvent deasphalting, solvent dewaxing, lube oil solvent refining, aromatic extraction, and butadiene extraction. These processes are briefly described below. 

The teed to the cat cracker in a typical refinery is a blend of gas oils from such operating units as the crude, vacuum, solvent deasphalting, and coker. Some refiners purchase outside FCC feedstocks to keep the FCC feed rate maximized. Other refiners process atmospheric or vacuum residue in their cat crackers. In recent years, the trend has been toward heavier gas oils and residue. Residue is most commonly defined as the fraction of feed that boils above 1,050°F (565 C). Each FCC feed stream has different distillation characteristics. 

Processes that have been combined with propane deasphalting include acid treating, cold fractionation of heavy lubricating oils, and selective solvent refining. 

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. 

Solvent extraction may also be used to reduce asphaltenes and metals from heavy fractions and residues before using them in catalytic cracking. The organic solvent separates the resids into demetallized oil with lower metal and asphaltene content than the feed, and asphalt with high metal content. Figure 3-2 shows the IFP deasphalting process and Table 3-2 shows the analysis of feed before and after solvent treatment. Solvent extraction is used extensively in the petroleum refining industry. Each process uses its selective solvent, but, the basic principle is the same as above. 

Chlorex Process (9, 13, 37o, 70, 133). Chlorex ( 3,jS -dichloroethyl ether) is especially suited for refining Pennsylvania oils since oil solubility in the solvent is fairly high, although it is used successfully on Mid-Continent residua provided that these have been deasphalted prior to solvent treatment. Relatively low temperatures (< 100°F.) are customarily used which may then require that dewaxing be carried out prior to refining, although in at least one instance refining is done in the presence of wax in... 

The US petroleum refining industry generates sales of over 730 billion with only about 143 plants. It employs 62,000 people. About 90% of the produets used in US are fuels of whieh 43% is gasoline. Figure 13.20.1 illustrates how the produets breakdown. The proeess is described in detail in Chapter 3. Emissions of hydrocarbons to the atmosphere occur at almost every stage of the production process. Solvents are produced in various processes and they are also used to extract aromatics Irom lube oil feedstock, deasphalting of lubricating base stocks, sulfur recovery from gas stream, production of solvent additives for motor fuels such as methyl tert-butyl ether and tert-amyl methyl ether, and various... 

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