Coal compositions

Details Coal compositions Coal compositions

1982-06-10

1985-05-07

Dixon, Jr., William R.

Fuel and related compositions

Liquid fuels

Aluminum or heavy metal, other than lead, containing

44 72, 252352, 252357, C10L 132

Patent

active

045156026

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION

The present invention relates to coal compositions and, more particularly, to novel, improved coal-water mixtures which can be used as fuels and as feedstocks for coal gasification and liquefaction processes.
Dwindling supplies of petroleum and natural gas and concerns about the regular availability of those products from foreign sources have led to increased interest by utilities and other consumers in the use of coal as an alternative fuel. One approach to this use of coal that is currently being investigated is the firing of coal-water mixtures or slurries. While such slurries do have drawbacks not found in conventional pulverized coals, these are not serious and are more than offset by the comparative ease with which a coal-water slurry can be handled.


BACKGROUND ART

The coal-water slurries reported in the patent and open literature for the most part have particle size distributions of 60-80 percent .+-.200 mesh (74 .mu.m).times.0 and ash contents of 3+ to over 10 wt percent. Such mixtures are described in U.S. Pat. Nos. 3,517,628 issued June 30, 1970, to H. Harnisch et al; 3,682,114 issued Aug. 8, 1972, to F. Scheubel et al; 3,762,887 issued Oct. 2, 1973, to Clancey et al; 3,764,547 issued Oct. 9, 1973, to Schlinger et al; 4,282,006 issued Aug. 4, 1981, to J. Funk; and 4,304,572 issued Dec. 8, 1981, to H. Wiese et al and in the following papers, all presented at the 4th International Symposium on Coal Slurry Composition, Orlando, Fla., May 10-12, 1982: K. Aoki et al, Pretreatment of Coal for Coal Water Slurries, Sumitomo Heavy Industries, Ltd.; R. Borio et al, Coal-Oil Mixture and Coal-Water Mixture Fuels for Steam Generators, Combustion Engineering, Inc.; G. Germane et al, Coal-Water Mixture Combustion Studies in a Laboratory Cylindrical Combustor, Combustion Laboratory, Brigham Young University; M. Ghassemzadeh et al, Rheology and Combustion Characteristics of Coal-Water Mixtures, Babcock and Wilcox Company; and R. Scheffee et al, Further Development of and Evaluation of Coal-Water Mixture Technology, Atlantic Research Corporation.
The Borio et al paper does refer to one slurried coal--identified as super clean beneficiated--that reportedly has an ash content of 1.1 wt. %. However, that is not on a moisture-free basis, meaning that the ash content of the coal on that basis is over two wt. %.
Furthermore, the seam from which the raw coal was mined is not identified. Consequently, the reported ash content of the product coal may or may not be particularly notable.
Also of importance is that the particle size distribution of the coal in the slurry described by Borio is only 85% 44 .mu.m.times.0. As a consequence, the substitution of that slurry for the existing fuel in an electrical generating unit, for example, would be apt to require extensive--and correspondingly expensive--retrofit of the steam generator; and a significant derating of the generator might result.


DISCLOSURE OF THE INVENTION

The novel coal-water slurries disclosed herein differ from those described above in that they have a particle size distribution of .gtoreq.95 percent .ltoreq.30 m . 0 and an ash content that can range down to 1.5-<0.3 wt. percent. As a result, they have superior combustion characteristics; and deratings can be minimized in oil-to-coal and other conversion schemes. Also ash handling, erosion and corrosion, and emission control are significantly less of a problem.
Typical properties of a slurry in accord with the principles of the present invention are tabulated below:


TABLE L ______________________________________ Particle Size Distribution 11 .mu.m .times. 0 Total Sulfur Content Wt. % 0.4 Ash Content Wt. % 0.3 Solids Content Wt % 70 BTU/Lb of Slurry 10,500 ______________________________________
Coal-water slurries of the character just described can (but do not necessarily have to be) prepared by milling or otherwise comminuting raw coal until it has been reduced in particle size to .gtoreq.95 percent ca. 250 .mu.m.times.(.mu.m equals microme

REFERENCES:
patent: 2422515 (1947-06-01), Anderson
patent: 3517628 (1970-06-01), Harnsch et al.
patent: 3682114 (1972-08-01), Scheubel
patent: 3762887 (1973-10-01), Clancey et al.
patent: 3764547 (1973-10-01), Schlinger et al.
patent: 4282006 (1981-08-01), Funk
patent: 4302212 (1981-11-01), Yamamura
patent: 4304572 (1981-12-01), Wiese et al.
Aoki et al., Pretreatment of Coal for Coal Water Slurries, 1982.
Borio et al., Coal-Oil Mixture and Coal-Water Mixture Fuels for Steam Generators, 1982.
Germane et al., Coal-Water Mixture Combustion Studies in a Laboratory Cylindrical Combustor, 1982.
Ghassemzadeh et al., Rheology and Combustion.
Scheffee et al., Further Development and Evaluation of Cool-Water Mixture Technology, 1982.
McCutcheon's Detergents and Emulsifiers, 1967 annual, Witco Chemical, New York, New York, pp. 34 and 94.

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