Hydrogasification of coal

Hydrogasification. Hydrogasification of coal involves reaction of hydrogen with coal carried out at elevated temperatures under high partial pressure of hydrogen. The objective is to add sufficient hydrogen to coal to produce methane as the major product. It has been found that many types of coal can be hydrogasi-fied if the coal is heated rapidly to reaction temperatures. Even under favorable conditions, however, conversion to methane is not complete and aromatics such as benzene are made as by-products. 

Hydrogasification of coal is also a very exothermic reaction. One means of absorbing the heat of reaction is to use a fluidized bed reactor and inject hydrogen and coal reactants at sufficiently low temperature so that the sensible heat required to heat coal and hydrogen to reaction temperature is equivalent to the heat of reaction. 

Figure 7. Flash hydrogasification of coal maximum percentage of carbon conversion to CHk vs. pressure (at 900°C). Solid residence time (ts) gas residence time (tg) North Dakota lignite (O) New Mexico subbituminous (O).

In contrast to hydrogenation and oxidation reactions, much less is known about the ability of materials to effect the catalysis of hydrogasification reactions. Alkali carbonates, 1-10 wt % catalyze the hydrogasification of coals and cokes at 800°-900°C (6). The suggested mechanism is that adsorption of the alkalies by carbon prevents graphitization of the surface. Zinc and tin halides are effective hydrogasification catalysts. There is, however, little kinetic information on any of the catalyzed hydrogasification reactions. 

Coal can be processed to H2 by heat from a high temperature, gas-cooled reactor at a process efficiency of 60—70%. Process steps are coal hquefaction, hydrogasification of the Hquid, and steam reforming of gaseous products (179). 

Chemistiy of Coal Utilization, 2d suppl. voL, Lowry [ed.], Wiley, New York, 1963) that there are three fundamental reactions the Boudouard reaction (27-17), the heterogeneous water-gas reaction (27-18), and the hydrogasification reaction (27-15). The eqmlibrium constants for these reactions are sufficient to calculate all the reactions listed. 

Methanation Section Test Conditions. To date, the HYGAS pilot plant has been operated with Montana lignite coal feed. This lignite is a low sulfur (usually less than 1 wt % ) coal which has good reactivity for hydrogasification. The coal is nonagglomerating (thus eliminating the need for pretreatment), and it represents the lowest rank of U. S. coals that are available for conversion to substitute natural gas. 

Hydrogasification -ofbiomass [FUELS FROM BIOMASS] (Vol 12) -of coal [FUELS, SYNTHETIC - GASEOUS FUELS] (Vol 12) -of oil shale [OIL SHALE] (Vol 17)... 

Anthony, D.B. "Rapid Devolatilization and Hydrogasification of Pulverized Coal" Sc. D. Thesis Dept of Chemical Engineering Mass Institute of Tech., Cambridge, 1974. 

Two gasification processes under development, namely High Temperature Winkler Gasification (HTW) and hydrogasification of lignite (HKV), encouraged to study the gasification behaviour of various brown coal lithotypes (15). 

Figure 16. Conversion as a function of time with hydrogasification of brown coal cokes. (Reproduced with permission from Ref. 19. Copyright 1983 Schriftleitung Braunkohle.)...

Yasnda et al. stndied the hydro-gasification of HOPE. Advanced rapid coal hydrogasification (ARCH) in Japan is developed as a route in the conversion of coal into synthetic natural gas. 

De volatilisation and Hydrogasification of Bituminous Coal. Fuel, 55, 12M28. 

Much work has been reported on the destruction of caking properties of coal. Low temperature carbonization, if carried far enough, drives off enough volatile matter so that the remaining char does not agglomerate. Examples of this are Consolidation Coal Co/s Montour char used in much of the early hydrogasification work, and the more recent char... 

To develop a correlation between the petrographic properties of coals and their suitability for hydrogasification. 

Particles from a run in which untreated coal was fed were also examined. This coal was from Pittsburgh No. 8 seam but from a different mine—Consolidation Coal Co/s Montour 4 mine. The hydrogasification reaction was conducted entirely in 18 feet of free fall. The run could not be completed because of gradual caking of coal in the feed tube and in the reactor. However, the structure of the residue that was obtained is of interest (Figure 4). It is much more uniform in appearance and reflectance than residues from runs with pretreated coal. Almost all of the particles have a degenerate foam structure—i.e., they are filled with... 

Pressurized Hydrogasification of Raw Coal In a Dilute-Phase Reactor... 

Results of our most recent FDP reactor operations are summarized in Table I and the analyses of the feed coals used are listed in Table II. The main objectives of these experiments were (1) to establish the feasibility of directly producing a high Btu gas by hydrogasifying raw coal in a continuous reactor at economical pressures, (2) to measure the yields and distribution of coal hydrogasification reaction products, and (3) to provide data for scaling up the FDP reactor. 

Table I. Operating Data for FDP Hydrogasification of Raw Coal (Feed Coal is 50 X 100 Mesh Except Where Noted)...

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