Exxon Donor Solvent Process

The solvent is first hydrogenated and then mixed with the fresh coal after which the slurry is passed through a preheater and into the reactor. The slurry product is separated by distillation into gas, naphtha, middle distillates, and a vacuum bottoms slurry this latter product is coked to produce additional liquid products. The process has the capability of producing high yields of low-sulfur liquids from bituminous (or subbituminous) coals and lignites (Table 19.4). 

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W. N. Mitchell, K. L. Trachte, md S. Zaczepinski, "Performance of Low-Rank Coals in the Exxon Donor Solvent Process," paper presented at / 0th Biennial Eignite Symposium, Grmd Porks, N.D., May 1979. 

The development of three-phase reactor technologies in the 1970 s saw renewed interest in the synthetic fuel area due to the energy crisis of 1973. Several processes were developed for direct coal liquefaction using both slurry bubble column reactors (Exxon Donor Solvent process and Solvent Refined Coal process) and three-phase fluidized bed reactors (H-Coal process). These processes were again shelved in the early 1980 s due to the low price of petroleum crudes. 

Other processes have been developed in recent years, especially during the decades of the 1960s and 1970s, to produce liquid fuels from coal. Examples include the H-Coal, Mobil M, Solvent Refined Coal, and Exxon Donor Solvent processes. 

In 1979, because of a lack of large samples, boiler fuel test programs will be limited to small scale equipment. However, in 1980, large samples of liquids in the 5,000-10,000 barrel range should become availabel from the H-Coal pilot plant at Catlettsburg, Kentucky and the Exxon Donor Solvent process at Baytown, Texas. It would be preferable to run a number of tests utilizing different utility sites and types of electric generation... 

Exxon Donor Solvent, and SRC-II, reactors are run at high severities to maximize distillate yield. Then, in the case of the H-Coal and SRC-II processes all the vacuum tower residue is sent to a partial oxidation gasifier to produce hydrogen. The amount of residue is set by the amount of hydrogen to be generated. The Exxon Donor Solvent process differs in that all or part of the vacuum tower residue is processed in a Flexicoking unit to recover additional liquids and to produce low Btu fuel gas. Partial oxidation can be used to process the remainder of the bottom to produce hydrogen. 

The Exxon Donor Solvent Process, Chemical Engineering Progress, p. 69, August 1976. 

Quinlan, C.W. Siegmund, C.W., Combustion Properties of Coal Liquids from the Exxon Donor Solvent Process, paper presented at the ACS National Meeting, Anaheim, CA., March 14,1978... 

Quinlan, C. W. and Siegmund, C. W., "Combustion Properties of Coal Liquids From the Exxon Donor Solvent Process", ACS Meeting Anaheim, California, March, 1978. 

Fig. 19.20. Schematic of Exxon Donor Solvent process. (CourtesyThe Pace Company, Denver, CO.)...

Char Oil Energy Development Process U.S. Department of Energy Exxon Donor Solvent Process fluidized bed combustion hydrogenated anthracene oil hydrogenated phenanthrene oil Hydrocarbon Research, Inc. 

A related reactor is that for coal liquefaction, which can be carried out in a three-phase slurry bubble column (see Fig. 5). Hydrogen can be supplied at the bottom of a column of downcoming product—oil. The solid coal reactant is blended with the product or carrier oil and fed at the top. The generic process depicted in Fig. 5 is a generalization of the liquefaction reactor in the Exxon Donor Solvent Process. As the gas flow rate increases, the bubbles change from uniformly small to chaotic. In the H-coal process, both the gas and a coal-oil slurry are fed from the bottom in an ebullating-bed reactor. Catalyst solids are fed from the top. This reactor operates as an expanded... 

The Exxon donor solvent process (Mitchell et al., 1979 Nowacki, 1979) (Figure 19.10) involves the noncataly tic liquefaction of crushed coal in the presence of hydrogen and a hydrogen donor solvent at 425°C-470°C (800°F-880°F) and 1500-2000 psi. The donor solvent may be a mid-distillate boiling range liquid (205°C-455°C [400°F-850°F]) that is also process-derived. 

Yields for Liquefaction of Illinois No. 6 Bituminous Coal from the Exxon Donor Solvent Process... 

Furlong, L. E., Effron, E., Vernon, L. W., Wilson, E. L., Coal Liquefaction—the Exxon Donor Solvent Process, presented at the AIChE National Meeting, Los Angeles, CA, Nov. 18, 1975. 

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