Solvents, coal liquefaction

W. R. Eppedy and J. W. Taunton, "Exxon Donor Solvent Coal Liquefaction Process Development," paper presented at Coal Dilemma II ACS Meeting, Colorado Spriags, Colo., Feb. 12, 1979. 

W. P. Epperly and T. W. Taunton, "Exxon Donor Solvent, Coal Liquefaction Process Development", Proceedings of the 13th Intersociety Energy Conversion Engineering Conference, Vol. 

Exxon Donor Solvent, Coal Liquefaction Process Development... 

Epperly, W.R. Taunton, J.W., Status and Outlook of the Exxon Donor Solvent Coal Liquefaction Process Development, paper presented at the Fifth Energy Technology Conference, February 27 - March 1, 1978, Washington, D.C. 

The authors are indebted to the sponsors of Exxon Donor Solvent Coal Liquefaction Process for supporting this work. The sponsors include the U. S. Department of Energy, Exxon Co.,... 

Removal of asphaltenes and preasphaltenes was easier than heteroatoms. At an increase of a hydrogen-to-carbon atomic ratio by 0.16, they were 80% removed. A comparison can be made with Synthoil process product of hydrogen-to-carbon atomic ratio equal to 1.04 which was hydrotreated to hydrogen-to-carbon atomic ratio equal to 1.24. The asphaltenes and preasphaltenes were 77% and 99% removed, respectively (7). Squires (8) concluded that the preasphaltenes can be converted to asphaltenes and oils with very little consumption of hydrogen. Asphaltenes are the major consumers of hydrogen. Although Squires conclusions were based on donor-solvent coal liquefaction, similar results were reported... 

Squires, A. M. Reaction Paths in Donor Solvent Coal Liquefaction, pre-... 

Maa, P S., Trachte, K. L., and Williams, R. D Solvent Effects in Exxon Donor Solvent Coal Liquefaction, presented at the ACS National Meeting, New York, Aug. 23 28. 

Wan, K.T. and B.L. Crynes. Catalyst Tailoring for Coal-Derived Liquids. cited in Shah, Y.T. and D.C. Cronauer. Oxygen, Nitrogen and Sulfur Removal Reactions in Donor Solvent Coal Liquefaction. Catalysis Reviews Science and Eng. 20(2) (1979) 209. 

Similar to the SRC version is the JExxow-Donor-Solvent-Coal-Liquefaction process (EDS) developed by Exxon. Rehydrogenation of the hydrogen-donating solvent is achieved in a special process stage through a fixed-bed catalyst (Figure 3.23). 

Data for the kinetics of coal liquefaction have been published in the literature (1-11). A review of the reported studies has recently been given by Oblad (12). The reported data were mostly obtained in bench-scale reactors. Guin et al. (7) studied the mechanism of coal particle dissolution, whereas Neavel (7), Kang et al. (8), and Gleim (10) examined the role of solvent on coal liquefaction. Tarrer et al. (9) examined the effects of coal minerals on reaction rates during coal liquefaction, whereas Whitehurst and Mitchell (11) studied the short contact time coal liquefaction process. It is believed that hydrogen donor solvent plays an important role in the coal liquefaction process. The reaction paths in a donor solvent coal liquefaction process have been reviewed by Squires (6). The reported studies examined both thermal and catalytic liquefaction processes. So far, however, very little effort has been made to present a detailed kinetic model for the intrinsic kinetics of coal liquefaction. 

Squires, A. M., "Reactor Paths in Donor Solvent Coal Liquefaction," a paper presented at conference on coal gasification/ liquefaction, Moscow, U.S.S.R. (October 1976), sponsored by U.S.-U.S.S.R. Trade and Economic Council, Inc. 

In addition to scale-up difficulties, there are a number of problems related to the stable operation of a bubble column associated with hydrodynamics. For example, consider the important commercial application of bubble columns in hydroprocessing of petroleum resids, heavy oils and synthetic crudes. Hydrodynamic cold flow and hot flow studies on the Exxon Donor Solvent coal liquefaction process (Tarmy et al., 1984) showed that much of the literature correlations for the hydrodynamic parameters (holdup, interfacial area and dispersion coefficients) obtained with cold flow units, at ambient conditions, are not applicable for commercial units operating at relatively higher pressures. In addition, the flow pattern in commercial units was considerably different. In the hydroprocessing of petroleum residues by the H-Oil and LC-Fining processes, refinery operations have experienced problems with nonuniform distribution of gas and liquid reactants across the distributor, maintaining stable fluidization and preventing temperature excursions (Beaton et al., 1986, Fan, 1989 and Embaby, 1990). Catalyst addition, withdrawal and elutriation have also been identified as problems in these hydrotreaters. 

Symp. Agglomeration and Conversion of Coal. West Virginia University, Morgantown, WV, 1975. Squires, A. M., "Reaction Paths in Donor Solvent Coal Liquefaction", Conf. Coal Gasification/ Liquefaction, Moscow, USSR., Oct. 1976. 

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