Crude residuum fraction

Agha Jari topped crude Gach Saran atmospheric residuum Kuwait and Lagomedio atmospheric residual 3 Jobo crude resin fraction asphaltene fraction Adriatic Sea atmospheric resid Gach Saran vacuum residuum... 

The residuum fraction of a full range crude is that fraction remaining after all of the distillate is taken overhead. As noted in Figure 1, this residuum fraction or resid may be obtained with either atmospheric or vacuum fractionation, yielding either long or short resid. 

The objectives of this chapter are twofold. First is to show the fundamentals of the chemistry and process engineering of asphaltenes during thermal treatment for achieving deep asphaltene cracking to increase and/or improve distillable yields of crude oil. The second is to present the current major processes for utilization of heavy oils and residuum fractions. 

To provide raw material for this comparative study of untreated and heat-treated oils, asphaltenes from Cold Lake crude (crude asphaltenes) and from Cold Lake vacuum residuum (residuum asphaltenes) were prepared by n-heptane precipitation as described in the Experimental section. The Cold Lake residuum fraction was prepared by Imperial Oil Enterprises, Ltd. at Sarnia, Ontario, Canada. The distillation history of this bottoms fraction indicates that the pot material was subjected to temperatures as high as 314-318°C during atmospheric and vacuum distillation. The length of time at 300°C or higher was about two hours. This is well in excess of what would be experienced in a pipestill and should have provided ample time for any decomposition. It should be noted, however, that since it was possible to maintain the system vacuum at 0.35 mm, the maximum temperature experienced by the residuum was not quite as high as it might be during refinery distillation (e.g. ca 350°C). 

Most of the oil that settled with sand on the top of the sand pack was extracted by heating it with water. Also, this oily fraction definitely has a higher density than the rest of the crude oil, indicating the possible presence of heavy metals, such as vanadium, nickel, or sulfur. Also, the oily portion that separated after heating which rose to the water surface could be crude residuum. The heavier oily material indicates a portion that is complexed with heavy metals and sulfur. 

Straight Run Asphalt. In cmde-oil refining, the crude oil at 340—400°C is injected into a fractionating column (5,6,19,20). The lighter fractions are separated as overhead products and the residuum is straight-reduced asphalt. 

The residuum from vacuum distillation became, and still is, the basic component of residual fuel oil. It contains the heaviest fraction of the crude, including all the ash and asphaltenes. It is extremely high in viscosity and must be diluted with light distillate flux (a low viscosity distillate or residual fraction which is blended with a high viscosity residual fraction to yield a fuel in the desired viscosity range) to reach residual fuel viscosity. The lowest value distillates, usually cracked stocks, are used as flux. In some cases the vacuum residuum is visbroken to reduce its viscosity so that it requires less distillate flux. 

Nitrogen, Sulfur and Oxygen Compounds. These are usually abbreviated as NSO compounds and sometimes referred to as asphaltics. Although present in small amounts, the N, S, and O atoms contribute greatly to the nonhydrocarbon fraction of a crude oil by their incorporation into hydrocarbon molecules. The residuum contains a high percentage of NSO compounds. 

Figure 2-77 shows how the weight distributions of the different molecular types vary during the fractional distillation of a naphthenic crude oil. Saturated aliphatic hydrocarbons (i.e., paraffins and naphthenes) are the predominant constituents in the light gasoline fraction. As the boiling point is raised, the paraffin content decreases, and the NSO content increases continuously. About 75 wt% of tbe residuum is composed of aromatics and NSO compounds. 

Fuel oil is any liquid petroleum product that is burned in a furnace for the generation of heat, or used in an engine for the generation of power, except oils having a flash point below 100°F and oil burned in cotton or wool burners. The oil may be a distillated fraction of petroleum, a residuum from refinery operations, a crude petroleum, or a blend of two or more of these. 

Crude oils are classified chemically according to the structures of tire larger molecules in the mixture. Classification methods use combinations of the words paraffinic, naphthenic, aromatic, and asphaltic. For instance, crude oil which contains a predominance of paraffinic molecules will yield very fine lubricating oils from the gas-oil fraction and paraffin wax from the residuum. Oh the other hand, if the larger molecules are aromatic and asphaltic, the heavier fractions of the crude oil are useful for pitch, roofing compounds, paving asphalts, and other such applications. 

The synthetic crude was produced by hydrogenating the IBP-350°F naphtha, the 350°-550°F light oil, and the 550°-850°F heavy oil fractions obtained from in situ crude shale oil by distillation followed by coking of the 850°F-f- residuum. Characterization of the syncrude was accomplished by examining the following fractions CB-175°F light naphtha, 175°-350°F heavy naphtha, 350°-550°F light oil, and 550°-850°F heavy oil. 

The acid, base, and neutral Lewis base fractions consist of polar molecules capable of hydrogen bonding and, therefore, of intermolecular association. These polar fractions, which constitute nearly two-thirds of the 675°C+ residuum, have high concentrations of heteroelements in comparison to the nonpolar aromatic and saturate hydrocarbons, as shown in Table IX for the residuum from a Russian crude oil. Infrared spectroscopy of the acid fraction revealed mostly pyrroles with phenols but only traces of... 

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