Exxon Donor Solvent coal liquefaction process

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. 

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. 

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. 

The Fluor Corporation recently reactivated and rebuilt the DOE test plant at Cresap, West Virginia, It conducted a coal liquefaction test project for DOE using Exxon s Donor Solvent Process, Oil and Gas Journal 1980, 78, p 71,... 

Exxon Donor Solvent, Coal Liquefaction Process Development... 

This paper describes the status of the development of the Exxon Donor Solvent (or EDS) coal liquefaction process. It includes an overview of the jointly funded project and a brief description of the EDS process. It also includes a discussion of the project status, including a description of coal feed flexibility, hydrogen and fuel gas production alternatives and the progress in the construction of the 250 T/D pilot plant. Other communications have covered the R D program, the outlook for commercialization, and the organization of the EDS Project (1,2, 3,, 5, 6, J) ... 

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 direct liquefaction technologies, which include Solvent Refined Coal, Exxon Donor Solvent and H-Coal processes have never been operated at a commercial scale. As discussed yesterday, these processes are not at advanced stages of development. The products from direct liquefaction processes are basically boiler fuels or synthetic crudes that could potentially be upgraded to... 

Figure 1. Exxon donor solvent (EDS) direct coal liquefaction process.

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.,... 

Exxon Donor Solvent Also known as EDS. A coal liquefaction process in which coal in solution in tetrahydronaphthalene is hydrogenated, using a cobalt-molybdenum-alumina catalyst. So called because the hydrogen is donated by the tetrahydronaphthalene to the coal. Developed from the Pott-Broche process. Piloted by Exxon Research Engineering Company in the 1970s and operated at 250 tons per day in the Exxon refinery in Baytown, TX, from 1980 to 1982. 

Pott-Broche A coal liquefaction process in which coal is dissolved in a mixture of tetrahydronaph-thalene and cresols, and then hydrogenated. Invented by A. Pott and H. Broche at IG Farbenindustrie, Germany in 1927 used by the Ruhrol Company in Germany between 1938 and 1944. See also Exxon Donor Solvent. 

In the 1960s, two direct coal liquefaction processes were under development in the U.S. the Exxon Donor Solvent (EDS) process and the H-Coal process. The distinguishing feature of the EDS process was a separate solvent hydrogenation step to carefully control the hydrogen donor characteristics of the solvent. The most important feature of the H-Coal process was the emulated bed reactor in the process. 

The Exxon donor solvent, direct liquefaction process also used hot oil drying. In this process, LRC is dried by a high-pressure hydrogenation reactor contact with hot recycle hydrogen donor solvent prior to entering. Unfortunately, no data were developed for solvent recovery after drying becanse the dried coal and vehicle solvent were reacted immediately with hydrogen in the Uqnefaction reactor. 

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. 

Research on the Exxon Donor Solvent (EDS) process began at Exxon in 1966 and by 1975 had progressed from investigations using 100 cm batch units to a continuous j-ton/day pilot plant. With the help of external funding, a 250-ton/day pilot plant was designed and constructed. The Exxon Coal Liquefaction Plant (ECLP) at Baytown, Texas began operations in April 1980, and was shut down and dismantled in late 1982. ... 

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). 

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