Upgrading process

Table 11. Properties of Shale Oil during the Unocal Upgrading Process ...

Fig. 1. The H. C. Starck pyrometallurgical upgrading process of Ta—Nb-containing tin slags where the soHd vertical bars represent electrodes. The product of (a) electrothermic reduction of Sn slag goes to (b) oxidation of Fe alloy 20—60 Ta + Nb and then to (c) electrothermic reduction of oxidized Fe ahoy.

Table 4. Enrichment of Tantalum in the Pyrometallurgical Upgrading Process...

The API gravity of tar sand bitumen varies from 5 to ca 10°API, depending on the deposit, and the viscosity is very high. Whereas conventional cmde oils may have a high (>100 MPa-s(=cP)) viscosity at 40°C, tar sand bitumen has a viscosity on the order of 10-100 kPa-s(10 -10 P) at formation temperature (ca 0—10°C), depending on the season. This offers a formidable obstacle to bitumen recovery and, as a result of the high viscosity, bitumen is relatively nonvolatile under conditions of standard distillation (Table 4) (12,13), which influences choice of the upgrading process. 

The processing of natural ores is perhaps not relevant to this discussion because the upgrading processes involve mechanical, electrical, or magnetic separation. These processes and their by-products normally do not contribute to environmental hazards. 

Heteroatoms nitrogen, oxygen, sulfur, and metals) are found in every crude oil, and the concentrations have to be reduced to convert the oil to transportation fuel. This is caused by the fact that if nitrogen and sulfur are present in the final fuel during combustion, nitrogen oxides (NO ) and sulfur oxides (SO ) form, respectively. In addition, metals affect many upgrading processes adversely, poisoning... 

Desulphurisation of hydrocarbon fuels has traditionally been carried out primarily as part of the refining and upgrading process. Accordingly by far the most advanced and best understood chemistry and technology is to be found in this area. Prior to the advent of major concern for environmental impact of fossil fuel combustion products relatively little was done to desulphurise hydrocarbon fuels (principally coal) prior to combustion and past effects of large scale consumption of high sulphur coals can still be seen in major industrialised areas around the world. 

If the gasifier product stream is intended for downstream use as the feedstock for further upgrading such as methanation, methanol or Fischer Tropsch synthesis, very thorough desulphuri-sation is essential since the catalysts in these upgrading processes are highly sensitive to sulphur poisoning. The methanation catalysts normally cannot tolerate more than 0.05 ppm of sulphur in the feedstock. In addition to H2S sulphur values in the gasifier product it may contain COS, CS2, mercaptans and thiophenes. These are normally removed by activated carbon or zinc oxide filters ahead of the sensitive synthesis catalyst beds. 

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The primary objective in the Upgrading process is to convert the heavy oil into a lower boiling product with low sulphur and nitrogen content. Sulphur is a by-product of this process. Figure 3 presents a schematic of Syncrude s Upgrading and will be used to describe the disposition of sulphur and its recovery at various stages in the process. 

Thus, the availability of detailed structural information regarding the feedstock and the produced coke is necessary for the optimization of various thermal upgrading processes. 

The ASCOT process is a residual oil upgrading process which integrates the delayed coking process and the deep solvent deasphalting process (low energy deasphalting, LED A) (Bonilla, 1985 Bonilla and Elliott, 1987 Hydrocarbon Processing, 1996). 

The FTC Process is a heavy oil and residuum upgrading process in which the feedstock is thermally cracked to produce distillate and coke, which is gasified to fuel gas (Miyauchi et al., 1981 Miyauchi and Ikeda, 1988). 

Residua from various processes are the preferred feedstocks for the production of hydrogen-rich gases. Such fractions with high sulfur and/or high heavy metal contents are difficult to handle in upgrading processes such as hydrogenation or coking and, for environmental reasons, are not usually used as fuels without extensive gas clean up. 

ASCOT process a resid (q.v.) upgrading process that integrates delayed coking and deep solvent deasphalting. 

Carbon rejection processes upgrading processes in which coke is produced, e.g., coking (q.v.). 

Separation process an upgrading process in which the constituents of petroleum are separated, usually without thermal decomposition, e.g., distillation and deasphalting. 

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