Vacuum residuum

The vacuum residua or vacuum bottoms is the most complex fraction. Vacuum residua are used as asphalt and coker feed. In the bottoms, few molecules are free of heteroatoms molecular weights range from 400 to >2000, so high that characteri2ation of individual species is virtually impossible. Separations by group type become blurred by the sheer mass of substitution around a core stmcture and by the presence of multiple functionahties in a single molecules. Simultaneously, the traditional gc and ms techniques require the very volatiUty that this fraction lacks. 

Fluid coking (Fig. 4) is a continuous process that uses the fluidized soflds technique to convert atmospheric and vacuum residua to more valuable products (12,13). The residuum is converted to coke and overhead products by being sprayed into a fluidized bed of hot, fine coke particles, which permits the coking reactions to be conducted at higher temperatures and shorter contact times than they can be in delayed coking. Moreover, these conditions result in decreased yields of coke greater quantities of more valuable Hquid product are recovered in the fluid coking process. 

VRDS Isomax [Vacuum residua desulphurization] A hydrodesulfurization process adapted for processing the residues from the vacuum distillation of the least volatile fraction of petroleum. An extension of the RDS Isomax process, developed and piloted by Chevron Research Company in the early 1970s. In 1988, one unit was under construction and one was being engineered. 

Asphalt chemicals, ethyleneamines application, 8 500t, 506 Asphalt emulsifier amine oxides, 2 473 fatty acid amides, 2 458 Asphalt emulsions, 10 131 Asphaltenes, in petroleum vacuum residua, 18 589-590 Asphyxiants, 21 836 Aspirating aerators, 26 165-169 compressed, 26 168-169 propeller driven, 26 168 submersible, 26 169, 170t subsurface, 26 168 Aspiratory, 11 236-237 Aspirin, 4 103-104, 104t, 701 22 17-21. See also Acetylsalicylic acid as trade name, 22 19 for cancer prevention, 2 826 Aspirin resistance, 4 104 ASP oil recovery process, 23 532-533 Assay format, competitive, 14 142 Assay limits, in Investigational New Drug Applications, 18 692 Assays, for silver, 22 650. See also... 

Petroleum vacuum residua, 48 589-591. See also Petroleum residua (resid) nitrogen and oxygen in, 48 590 Petroleum waxes, 48 670-671 26 214-218 applications for, 26 218 production of, 26 216... 

For many years, petroleum and heavy oil were very generally defined in terms of physical properties. For example, heavy oil was considered to be a crude oil that had gravity between 10 and 20° API. For example. Cold Lake heavy crude oil (Alberta, Canada) has an API gravity equal to 12°, but extra-heavy oil (such as tar sand bitumen), which requires recovery by nonconventional and nonenhanced methods, has an API gravity in the range 5 to 10°. Residua would vary depending on the temperature at which distillation was terminated, but vacuum residua were usually in the range 2 to 8° API. 

Residua are black, viscous materials obtained by distillation of a crude oil under atmospheric pressure (atmospheric residuum) or under reduced pressure (vacuum residuum). They may be liquid at room temperature (generally, atmospheric residua) or almost solid (generally, vacuum residua) depending on the cut point of the distillation or depending on the nature of the crude oil (Speight, 1999 Speight and Ozum, 2002). 

Another method (ASTM D-4808) covers the determination of the hydrogen content of petroleum products, including vacuum residua, using a continuous-wave, low-resolution nuclear magnetic resonance spectrometer. Again, sample solubility is a criterion that will not apply to coal but will apply to coal extracts. More recent work has shown that proton magnetic resonance can be applied to solid samples and has opened a new era in coal analysis by this technique (de la Rosa et al., 1993 Jurkiewicz et al 1993). 

The feeds to these types of units are usually atmospheric and vacuum residua. The products include feeds for the production of transportation fuels, fuel oils, olefins, etc. However, the operating conditions of the reactor, whether it is a fluid catalytic cracking unit or a fixed-bed unit, is dependent upon the desired product slate and the properties of the feed. 

In short, distillation is, at best, looked upon as a means by which the lower-boiling fractions can be separated from a feedstock prior to being subjected to a suitable conversion (or refining) method. It is, in fact, the means by which the undesirable higher molecular weight materials are removed from the feedstock as atmospheric or vacuum residua. It would, indeed, be a very rare occasion if the distillation process actually served as an efficient means of desulfurization rather than a concentration process. 

Table 7-4 Increased Sulfur Content of Vacuum Residua over Atmospheric Residua... 

In order to satisfy the changing pattern of product demand, significant investments in refining conversion processes will be necessary to profitably utilize the heavy oils and residua. The most efficient and economical solution to this problem will depend to a large extent on individual refinery situations. However, the most promising technologies will likely focus on the conversion of vacuum residua and extra-heavy crude oils into useful low-boiling and middle distillate products. 

The ET-II process is a thermal cracking process for the production of distillates and cracked residuum for use as a metallurgical coke and is designed to accommodate feedstocks such as heavy oils, atmospheric residua, and vacuum residua (Kuwahara, 1987). The distillate (referred to in the process as cracked oil) is suitable as a feedstock to hydrocracker and fluid catalytic cracking. The basic technology of the ET-II process is derived from that of the original Eureka process. 

The HOT process is a catalytic cracking process for upgrading heavy feedstocks such as topped crude oils, vacuum residua and solvent deasphalted bottoms using a fluidized bed of iron ore particles (Ozaki, 1982). 

The low energy solvent deasphalting process selectively extracts the more paraffinic components from vacuum residua while rejecting the condensed ring aromatics. As expected, deasphalted oil yields vary as a function of solvent type and quantity, and feedstock properties (Chapter 7). 

The Solvahl process is a solvent deasphalting process for application to vacuum residua (Peries et al., 1995 Hydrocarbon Processing, 1996 Hydrocarbon Processing, 1998). 

The ABC process can be used for hydrodemetallization, asphaltene cracking and moderate hydrodesulfurization as well as sufficient resistance to coke fouling and metal deposition using such feedstocks as, vacuum residua, thermally cracked... 

The CANMET hydrocracking process is used for heavy oils, atmospheric residua, and vacuum residua (Table 9-5) (Pruden, 1978 Waugh, 1983 Pruden et al., 1993). The process does not use a catalyst but employs a low-cost additive to inhibit coke formation and allow high conversion of heavy feedstocks (such as... 

The Hyvahl F process is used to hydrotreat atmospheric and vacuum residua to convert the feedstock to naphtha and middle distillates (Hydrocarbon Processing, 1998). 

Operating with the expanded bed allows the processing of heavy feedstocks, such as atmospheric residua, vacuum residua, and oil sand bitumen. The catalyst in the reactor behaves like fluid that enables the catalyst to be added to and withdrawn from the reactor during operation. The reactor conditions are near isothermal because the heat of reaction is absorbed by the cold fresh feed immediately owing to thorough mixing in the reactors. 

The MRH process is a hydrocracking process designed to upgrade heavy feedstocks containing large amount of metals and asphaltene, such as vacuum residua and bitumen, and to produce mainly middle distillates (Sue, 1989). The reactor is designed to maintain a mixed three-phase slurry of feedstock, fine powder catalyst and hydrogen, and to promote effective contact. 

The RCD Unibon (BOC) process is a process to upgrade vacuum residua (Table 9-16) (Thompson, 1997 Hydrocarbon Processing, 1998). 

RCD Unibon (BOC) process is a process to upgrade vacuum residua using hydrogen. 

VRDS [Vacuum Residua DeSulfurization] A general name for hydrotreating processes for removing sulfur from the residues from the vacuum distillation of petroleum residues. See also VRDS Isomax. 

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