Retorting oil shales

Temperature and Product Yields. Most oil shale retorting processes are carried out at ca 480°C to maximize liquid product yield. The effect of increasing retort temperature on product type from 480 to 870°C has been studied using an entrained bed retort (17). The oil yield decreased and the retort gas increased with increased retorting temperature the oil became more aromatic as temperature increased, and maximum yields of olefinic gases occurred at about 760°C. Effects of retorting temperatures on a distillate fraction (to 300°C) are given in Table 6. 

Boade, R.R., M.E. Kipp, and D.E. Grady (1981), A Blasting Concept for Preparing Vertical Modified in Situ Oil Shale Retorts, Sandia National Laboratories Report SAND81-1255. 

FIGURE 6.7 Steps in oil shale retorting are shown. Oil shale is erushed and then heated in a retort to drive off the oil that is trapped in the roek. Any oil left behind, as well as partieulates returned to the process as the reeovered oil is processed, is burned to provide heat for the retorting. The oil that is recovered from the shale is chemically treated to produce synthetic crude for further processing in conventional refineries. Courtesy, Amoco Oil Company. 

Hargis KM, Tillery MI, Ettinger HJ, et al. 1986. Industrial hygiene study of a true in-situ oil shale retorting facility. Am Ind Hyg Assoc J 47 455-464. 

Sklarew DS, Hayes DJ. 1984. Trace nitrogen-containing species in the offgas from 2 oil shale retorting processes. Environ Sci Technol 18 600-603. 

Dobson KR, Stephenson M, Greenfield PF, etal. 1985. Identification andtreatability of organics in oil shale retort water. Water Res J 19 849- 856. 

No information was available on the costs of using the HRS retorting process to treat hazardous or mixed wastes. Cost estimates for the full-scale application of the HRS process for oil shale retorting may be found in D120672. 

Fruchter, J. S., Wilkerson, C. L., Evans, J. C., Sanders, R. W. 1980. Elemental partitioning in an aboveground oil shale retort pilot plant. Environmental Science and Technology, 14, 1374-1381. 

Golubev, N. 2003. Solid oil shale heat carrier technology for oil shale retorting. Oil Shale, 20, 324-332. 

We will consider three processes in more detail to show how the sulfur in the original feedstock material (coal or oil shale) is recovered as elemental by-product sulfur. In this way yields of sulfur per barrel of product can be computed. The three processes will illustrate examples of coal gasification for production of SNG, methanol or indirect liquids, direct liquefaction for production of naphtha and synthetic crude oil and finally, oil shale retorting for production of hydrotreated shale oil. 

FIGURE 8 The three heating methods tor oil shale retorting, (a) Directly heated retort (b) indirectly heated retort, gas-to-solid heat exchange (c) indirectly heated retort, solid-to-solid heat exchange. [Reprinted with permission from Probstein, R. F., and Hicks, R. E. (1990). Synthetic Fuels, pH Press, Cambridge, MA.]... 

Two indirectly heated oil shale retorting technologies employing solid-to-solid heat transfer have been described in connection with coal pyrolysis. They are the TOSCOAL process, called the TOSCO process when used with oil shale, and the Lurgi-Ruhrgas process. The former process was fully developed before operations were terminated, and the latter has been commercialized in connection with coal devolatilization and hydrocarbon pyrolysis. 

The nitrophenols have been identified in effluents from several industries. 2-Nitrophenol has been detected in effluents from photographic and electronics industries (Bursey and Pellizzari 1982). Nitrophenols (isomer unidentified) at a concentration of 5 mg/L was detected in oil shale retort water (Dobson et al. 1985). Nitrophenols have been identified in effluents from other chemical plants, as well. 4-Nitrophenol has been identified in effluent from a pesticide plant (EPA 1985). Both 2-nitrophenol and 4-nitrophenol were detected in the final effluent from the waste water of a petroleum refining industry (Snider and Manning 1982). Nitrophenols have also been identified in primary and secondary effluents of municipal waste water treatment plants. For example, both nitrophenols were identified in the secondary effluent from a waste water treatment plant in Sauget, Illinois, (Ellis et al. 1982), and 4-nitrophenol was detected in both primary and secondary effluent... 

Gogolak CV. 1985. The radiological impact of atmospheric emissions from oil shale retorts. Environ Int 11 57-64. 

Braun, R. L. Chin, R. C. Y. Computer Model for In Situ Oil Shale Retort-... 

B7. Berti, L., Operational criterion of a spouted bed oil shale retort. D.Sc. Thesis, Colorado School of Mines, Golden, 1968. 

These properties of oil shale lead to basic assumptions concerning the fate of trace elements during oil shale retorting. From an economic viewpoint, no trace elements occur in extractable quantities in typical oil shale. Any by-product recovery of inorganic materials probably will... 

Mass Balance Considerations. The values of ER for the Fischer assay spent shale are contained in Table V. If it is assumed that the relative standard deviation in the analyses is 10%, then the relative probable error in ER would be 14% if the analytical errors were indeterminant and 20% if the errors were determinant (38). The mass ratio of OS-l/FS is 1.24 as derived from the assay data in Table I. It is not possible to conclude that any trace elements are mobilized from the solid material during the assay retorting. The ER results obtained for arsenic, selenium, and molybdenum indicate the importance of analytical precision in detecting any trace element mobilization during oil shale retorting. The values of RI contained in Table V show a similar dependence on analytical precision. The probable errors in these values are also between 14 and 20% if the relative standard deviation in the analytical results is assumed to be 10%. These results indicate that, within experimental error, none of the trace elements have been lost during Fischer assay. More definitive conclusions on whether elements are mobilized or lost can only be reached with more precise analytical... 

Lithophile elements such as magnesium, potassium, calcium, rubidium, strontium, the rare earth elements, and uranium (9) are not expected to be mobilized during oil shale retorting. Many of these elements can be determined quite precisely at trace element levels. Thus, investigation of the values of ER and RI for these elements should help to establish the reliability of the ER and RI values. 

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