US3762887A

US3762887A - Fuel composition

Info

Publication number: US3762887A
Application number: US00098037A
Authority: US
Inventors: J Clancey; J Phinney; T Regan; E Wasp
Original assignee: Consolidation Coal Co
Current assignee: Consolidation Coal Co
Priority date: 1970-12-14
Filing date: 1970-12-14
Publication date: 1973-10-02
Anticipated expiration: 1990-10-02

Abstract

A liquid fuel composition that has as its sole consituents, particulate coal and water. The particulate coal and water are mixed to form a homogeneous slurry that can be handled, stored, pumped and burned in substantially the same manner as conventional liquid fuels. The coal and water in the slurry have the relative proportions of between 54 and 69 per cent by volume coal and 46 to 31 per cent by volume water. The coal particles have a size distribution so that substantially all of the particles pass through a 4 mesh Tyler Standard Screen and between 18 and 33 per cent by weight pass through a 325 mesh Tyler Standard Screen. Less than 60 weight per cent of the coal particles have a size that remains on a 28 mesh Tyler Standard Screen and the remaining coal particles have a size that passes through a 28 mesh Tyler Standard Screen and remains on a 325 mesh Tyler Standard Screen.

Description

United States Patent 1 1 1111 3,762,887

Clancey et al. I 1 Oct. 2, 1973 FUEL COMPOSITION 3,341,256 9/1967 Adams ..44 51 3,359,040 12/1967 E r 44/51 [751 lm'emmsl James Chm"; mm 1 3,124,086 3 1964 Sa g e et al. 44 51 both of Pittsburgh, Pa.; Thomas J. Regan Mamnvme V Edward Primary Examiner-Daniel E. Wyman wasp San Rafael Assistant Examiner-Mrs. Y. H. Smith Assignee: Consolidation Coal Company, Attrney-D. FOWlCl', Jr. and Stanley Price, Jr.

Pittsburgh, Pa.

[22] Filed: Dec. 14, 1970 {\FSTRACT A I1qu1d fuel compositlon that has as its sole cons1tu- PP N 98,037 1 ents, particulate coal and water. The particulate coal Related Us Application Data and water are mixed to form a homogeneous slurry that can be handled, stored, pumped and burned in substan- I63] Commuauon of 1966 tially the same manner as conventional liquid fuels. The

abandoned, which is a continuation-in-part of Ser, No.

229,423 Oct 9, 1962 abandoned. coal and water in the slurry have the relative proportions of between 54 and 69 per cent by volume coal and 52 us. (:1. 44/51 46 Per by vlume The Coal P [51] 1 Clm 1/32 have a size distribution so that substantially all of the [58] Field 6: Search 44/51; 252/31; Particles Pass 4 mesh Tyler Standard Screen 100/7 75 and between 18 and. 33 per cent by weight pass through a 325 mesh Tyler Standard Screen. Less than 60 wieght [56] References Cited per cent of the coal particles have a size that remains on a 28 mesh Tyler Standard Screen and the remaining UNITED STATES PATENTS coal partilces have a size that passes through a 28 mesh 2,233,323 lgliller Tyler Standard Screen and remains on a 325 mesh rowne 728,855 5 1903 Browne 44 51 Tyler Standard Screen 3,168,350 2/1965 Phinney et al. 44/51 4 Claims, 1 Drawing Figure VISCOSITY. v's FINES LEVEL VISCOSITY BROOKFIELD 6 I I 1 I 1 I I 1 5 I0 I5 3O WEIGHT- THROUGH 325 MESH PAIENIEDII" 3.762.887

VISCOSITY V'S FINES LEVEL VISCOSITY BROOKFIELD 5 I 1 I' I J 5 IO I5 20 25 3O 35 WEIGHT 73 THROUGH 3 25 MESH INVENTORS J.A. PHINNEY E.J. WASP T.J. REGAN J. T. CLANCEY NEW FUEL COMPOSITION This application is a continuation of our copending application Ser. 'No. 518,425, filed Jan. 3. 1966, entitled A New Fuel Composition," now abandoned which in turn is a continuation-in-part of application Ser. No. 229,423, filed Oct. 9, 1962, entitled -A New Fuel Composition," which is now abandoned.

This invention relates to anew composition of matter which is suitable for use as a liquid fuel, and, more particularly, to a coal-water slurry which has the characteristics essential to use as a liquid fuel for cyclone burners, and the like. i

The primary object of this invention is to provide a coal-water slurry that can be handled, stored, pumped, and burned as a liquid fuel.

Other objects of this invention will become apparent as the invention is more fully hereinafter described.

In accordance with our invention, we have provided a coal-water slurry, that is,"a mixture of water and finely divided coal, which simulates a fuel oil in the following respects:

l. lts composition is homogeneous and remains substantially so after being stored for days and even months. To the extent there is any settling of the coal particles, and it is at most slight, the settled phase is homogeneous; that is, little or no size segregation of the particles occurs duringthe slight settling.

2. It is readily pumped and fedunder control of automatic valves or other liquid control means to a coal conversion unit.

3. It is readily burnedwithout prior removal of the water, for example, in a cyclone burner.

The new liquid fuel of our invention has the following composition. It consists essentially of finely divided coal and water in the relative proportions of 54 to 69] For a better understanding of our invention, reference should be had to the following description and to the accompanying drawing in which is shown a graph f the correlation between viscosity and per cent by weight of the coal particles in the coal having a size less than 325 mesh Tyler Standard screen.

The preferred method of making the new fuel of our invention is described in U.S. Pat. No. 3,168,350 entitled Transportion of Coal by Pipeline issued Feb. 2,

I0 1965, and assigned to the assignee of the present invention; Specifically this method comprises blending a finely divided coal having a nominal top size between 4 and 28 mesh Tyler Standard screen, obtained by conventional grindingor crushing means such as rod mills,

5 hammer mills, etc., with a fraction of coal particles passing through a 325 mesh Tyler Standard screen in :such relative proportions as to yield a composition having the size specifications set forth above. The mixture is then stirred to effect homogeneity. The requisite water to yield the desired coal concentration is preferag bly added to the fractions of coal before blending to fa-j cilitate such blending. Any additional 4 X 28 mesh parti cles that may be required to meet the recited specifications are also added. The coal concentrations and thei size distributions of the coal of examples of coal-water 'range of'our invention and is included for purposes of comparison only.'The coal employed in these examples was a Pittsburgh Seam coal having a specific gravity of 1.35. With such specific gravity, the range of concentrations of the coal expressed as per cent by weight rather than per cent by volume is 62 to 74 (correspondto 54 to 69 per cent by volume set forth above).

TABLE 1 Percent by weight Example A. B C D E F G H I J K L M N O P Q R 0 0 0 0 0 0 0 Tr. 0 0 0.4 0 0 0 0 Tr. 0 0

Through 325 mesh 27. 7 30.0 22 27. 5 26. 7 22. 7 24. 4 23.8 23.7 28. 6 25.8 26.1 27. 5 30. 2 24. 5 30. 6 28.8 11.4

per cent by volume of coal and 46 to 31 per cent by volume of water. The size distribution of the finely divided? coal is such that all the particles will pass through a 4. mesh Tyler Standard screen. Between 18 and 33 per? cent by weight of the particles pass through a 325 mesh Tyler Standard screen. The balance of the coal particles have a range of sizes between 325. mesh and mesh, with less than ,60'per cent by weight of the total! coal in the range between 28 and 4 mesh.

We prefer, however, that the compositions have a;

coal concentration in the slurry between 57 and 65 per 60 In general the compositions of this invention have the appearance of a black heavy fuel oil such as that commonly referred to as Bunker C fuel oil. Their specific gravity is about 1.19. Their net BTU content (that is,, "the BTU content of the coal less the BTUs consumed: in vaporizing the water present is about 9,000 BTU/1b.. of slurry for a Pittsburgh Seam bituminous coal which has been subjected to conventional cleaning procedures.

One of the most important properties of our new fuel is its stability upon storage for protrated periods of time. Even on extended periods of storage there occurs little or no segregation of sizes, and changes in concentration are'slight. The following Table 11 illustrates the behavior of a typical composition (Example A of Table 1) upon standing during three days in a 25-foot high TABLE ll Thru Cone. On 8 Mgs h8 x 14 Mesh. 325 Mes h Top 1st Day 67.7 7 21.1 25.3 Bottom 1st Day 71.1 5.9 22.7 23.4 Top 3rd Day 70.0 6.6 21.3 25.5 Bottom 3rd Day 71.0 6.1 22.9 24.0

In general the viscosity of our new fuel is in the range of that of hot Bunker C fuel oil. It can be readily pumped in centrifugal or positive displacement pumps. The drawing shows graphically a correlation of viscosity with weight per cent of through 325 mesh particles in the coal. This correlation is typical of the compositions of our invention, although the minimum may shift somewhat depending upon the precise size distribution. The one shown in the drawing was obtained by blending in water a relatively coarse coal fraction A with a relatively fine coal fraction 8 to yield a final coal concentration of 63 per cent by weight with varying amounts of through 325 mesh coal to provide samples for the viscosity determinations with the exception of the point on the curve designated G. This point represents the viscosity of themixture obtained by making up a 63 per cent concentration of the coal listed as Example R in Table I, i.e., a natural grind. The viscosities shown in the drawing are those obtained in a Brookfield Synchro-Lectric Viscosimeter (made by the Brookfield Engineering Laboratories, Stoughton, Mass.). Our new fuel is a non-Newtonian pseudoplastic fluid, and as such has no ordinary viscosity. The size distributions of .the two fractions A and B are listed in Table III below.

TABLE Ill Fraction A Fraction 8 (1: by Weight) by Weight) n 8 mesh 1.2 g On l4 mesh 13.7 On 28 mesh 29.1 0 On 48 mesh 20.7 0.6 On 100 mesh 13.9 1.0 On 200 mesh 6.1 4.9 On 325 mesh 3.9 9.6 Trhough 325 mesh 11.4 83.4

We have found the compositions of this invention to be completely satisfactory as a substitute for fuel oil fed to a cyclone type burner. The burner needs no modification to permit the use of our new fuel. As an example, a coal-water slurry having the specifications of Example A in Table I was prepared from a Pittsburgh Seam coal that had a BTU content of 13,500 on a moisturefree basis. The coal had the following proximate analysis (dry basis):

Volatile Matter 388% Fixed Carbon 53.6% Ash 7.6%

The liquid slurry was kept in a storage tank during the period of the burning test, and was withdrawn continuously under the control of a conventional liquid fuel valve. A small amount of circulation comparable to that used in Bunker C fuel oil tanks was maintained in the tank. The pump used to withdraw the slurry from the tank was a centrifugal pump normally used in cyclone burner installations. During the period of test, i.e., 23 days, the flow of fuel was trouble-free. The performance of the burner was essentially the same as though fuel oil were being employed, allowing for the difference in BTU contents. There was no visual difference between the slurry flame and a fuel oil flame. The steam formed by the conversion of the slurry water was discharged from the burner in the same manner as the steam formed by combustion.

According to the provisions of the patent statutes, we have explained the principle, preferred construction, and mode of operation of our invention and have illustrated and described what we now consider to represent its best embodiment; However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. A homogeneous composition of matter suitable for use as a liquid fuel consisting essentially of particulate coal and water in the relative proportions of 54 to 69 percent by volume of coal and 46m 31 per cent by volume of water, said particulate coal having a size distribution substantially as follows: 0 per cent by weight on 4 mesh Tyler Standard screen, 18 to 33 per cent by weight less than 325 mesh, less than 60 per cent by weight between 4 and 28 mesh, and the balance in the size range of 28 to 325 mesh.

2. A homogeneous composition of matter suitable for use as a liquid fuel consisting essentially of particulate coal and water in the relative proportions of 57 to per cent by volume of coal and 43 to 35 per cent by volume of water, said particulate coal having a size distribution substantially as follows: 0 per cent by weight on 4 mesh Tyler Standard screen, 22 to 28 per cent by weight less than 325 mesh, 20 to 30 per cent by weight between 4 and 28 mesh, and the balance in the size range of 28 to 325 mesh.

3. A homogeneous composition of matter suitable for use as a liquid fuel consisting essentially of particulate coal having a specific gravity of about 1.35 and water in the relative proportions of about 68 per cent by weight of said coal and about 32 per cent by weight of water, said particulate coal having a size distribution substantially as follows: 0 per cent on a 4 mesh Tyler Standard screen, about 28 per cent by weight less than 325 mesh, about 25 per cent by weight between 4 and 28 mesh, and the balance in the size range of 28 to 325 mesh.

4. A composition of matter suitable for use as a liquid fuel consisting essentially of particulate coal having a specific gravity of about 1.35 and water in the relative proportions of about 68 per cent by weight of said coal and about 32 per cent by weight of water, said particulate coal having a size distribution substantially as follows:

Claims

2. A homogeneous composition of matter suitable for use as a liquid fuel consisting essentially of particulate coal and water in the relative proportions of 57 to 65 per cent by volume of coal and 43 to 35 per cent by volume of water, said particulate coal having a size distribution substantially as follows: 0 per cent by weight on 4 mesh Tyler Standard screen, 22 to 28 per cent by weight less than 325 mesh, 20 to 30 per cent by weight between 4 and 28 mesh, and the balance in the size range of 28 to 325 mesh.
3. A homogeneous composition of matter suitable for use as a liquid fuel consisting essentially of particulate coal having a specific gravity of about 1.35 and water in the relative proportions of about 68 per cent by weight of said coal and about 32 per cent by weight of water, said particulate coal having a size distribution substantially as follows: 0 per cent on a 4 mesh Tyler Standard screen, about 28 per cent by weight less than 325 mesh, about 25 per cent by weight between 4 and 28 mesh, and the balance in the size range of 28 to 325 mesh.
4. A composition of matter suitable for use as a liquid fuel consisting essentially of particulate coal having a specific gravity of about 1.35 and water in the relative proportions of about 68 per cent by weight of said coal and about 32 per cent by weight of water, said particulate coal having a size distribution substantially as follows: