US1496778A - Art of fuels - Google Patents

Description

?atented June 10, 1924.

WILLIAM E'UNTLEY HAMPTON, OF NEW YORK, N. Y.

ART OF FUELS.

R Drawing.

. l0 able others skilled in the art to which it appertains to make and use the same.

This invention relates to the art' of fuels; and it relates especially to the utilization for fuel of solids containing a considerable per- 5 centage of combustible matter but having an excessively high content of ash. In particular, the invention relates to the utilization of bituminiferous solids, such as oil shale and other minerals of the general character which may contain up to as high as 35 or 40 per cent combustible matter, the balance being principally ash.

While the invention is not to be under stood as limited to the treatment and utilization of oil-bearing shales as fuel, this constitutes at present the most important practical application of the invention and will therefore be more particularly referred to hereinafter for the sake of a concrete example in explaining the principles upon which the invention is based.

It is well known that bituminous shale,

particularly shale that is relatively high in bitumen content, can be burned to a certain extent in furnaces provided with grates specially designed to receive and handle fuel extremely high in ash. The practical utilization of shale in this manner is very limited in practice, however, and it cannot be said to have proved successful except under certain exceptional conditions. The

highest grade of oil-bearing or bituminous shale seldom runs higher than 4.0 per cent combustible matter, and ordinarily a shale at running 30 to 35 per cent combustible is considered 00d. Oil-bearing shale invariably runs higher than per cent ash, commonly averaging around 65 to 70 per cent ash. Of the combustible content, from 60 so to 7 0 per cent is volatile combustible matter,

while 40 to 30 per cent is fixed carbon. It is evident that the utilization of such material as this for fuel is beset with serious difliculties; and it is on account of these difficulties and also because of the. fact that under ordinary circumstances other and Application filed July 9,

1920. Serial No. 395,017.

more readily utilizable fuels are available at comparatively. low cost, that the practical utilization of shale for fuel has not progressed far heretofore. Under certain circumstances, however, it would be of the highest practical value and importance to be able to make use of oil-bearing shale as a fuel. This is particularly true in certain sections in the western part of the United States where there are extensive deposits of oil bearing shale which could be profitably worked were it not for high cost of fuelrequired in the treatment of such shale for recovery and refining of the contained bitumens. In order to work these shale deposits profitably, it is essential to conduct at least the extraction and recovery of the contained bitumens from the shale at or close to the pit or mine, the cost of transporting the untreated shale from the field to refineries located at any considerable distance fromthe pit or mine being prohibitive because of the fact that 60 to 70 per cent of the shale as mined is simply waste material. According to the practice generally followed heretofore, the retorts or stills employed for recovery of the bitumens from shale have been commonly fired either by means of crude shale oil or by means of coal transported 35 from the nearest available supply and used either directly or indirectly through. the intermediary of gas producers. Whichever method be adopted, the resultant fuel cost represents a seriously large proportion of so the value of the marketable output derived from a shale treating plant; and it is a principal object of the present invention to substantially reduce this fuel cost by making possible the burning of oil-bearing shale 9B in a form and in a manner that ensures production of the necessary heat efiiciently and economically. The invention has several aspects, including the preparation of a novel fuel by 'a novel method, and a process of burning the saidffuel.

In accordance with the present invention, a radical departure is made from the earlier methods in which shale was burned on a furnace grate; and instead, the shale is we burned in pulverized or ground condition, in a manner analogous to the burning of pulverized coal. However, the problem is not merely one of blowing pulverized shale into a combustion chamber in the same way that He powdered coal can be employed. 'In the first place, the high ash contentof shale renders it impossible, without observing special conditions to be hereinafter pointed out, to obtain a self-sustaining flame simply by blasting or blowing powdered shale into a combustion chamber in the same way that is done in the case of powdered coal. Moreover, the pulverization of oil bearing shale is in itself a troublesome problem, and even assuming pulverized shale of the requisite degree of fineness to be attainable by ordinary methods, such material has certain" peculiar characteristics that, render it difficult to handle in the same manner that pulverized coal is handled.

The problem to be solved therefore includes the provision of a pulverulent fuel comprising bituminous shale but of. such modified composition as to enable it to be burned in a manner analogous to that employed in burning powdered coal; and toaccomplish the preparation of such a pulverulent fuel in an economical and ready shale a pulverulent fuel analyzing not over- 50 per cent .ash and containing at least 3 per cent of volatile matter, the shale,

crushed to say one-half inch mesh size, is mixed with a sufiicient quantity of a solid carbonaceous fuel having an ash content of less than 50 per cent, to bring the analysis of the mixture within the limits above specified. This carbonaceous fuel employed to enrich the shale or, in efi'ect, to lower the ash content thereof, may be any one of various kinds; "but it should be one which itself is readily pulverizable, and which, when added in the necessary proportions to give a composite fuel of the required analysis, will wholly or largely eliminate the described dificulties encountered in attempting to grind oil-bearing shale alone. So far as I am aware, this method of grindin an oilbearing solid is broadly novel. rdinary coal, either high grade or low grade, and especially coal of the type commonly employed in firin cement kilns, iron furnaces, etc. with pow ered coal burners, is suitable for this purpose. It is also entirely feasible to use coke breeze, culm, slack, or other materials of this character; and it is even possible to use lignite which has been dried to reduce its initial high moisture content sufficlently. In a typical instance, a shale having the above analysis is mixed with about an equal quantity of a low grade coal con= Leeavva matter, and 30 per cent fixed carbon. This mixture is readily reduced to a fine powder 7 in an ordinary coal grinder without exhibiting any tendency to gum up, or to clog the screens of the grinding apparatus; whereas when it is attempted to grind oil shale alone inthe same apparatus, the shale shows a strong tendency to gum up and flake when the grinder becomes warm, and such small proportion'of fine powder as is produced from the shale is of an oily character which causes it to cling tenaciously to the screens andfito clog'the same. V

The aforesaid mixture of shale and low grade coal can bereadily ground to very fine mesh without any difliculty whatever. In a typical instance, 86 per cent of the resultant pulverized mixture passed a 300- mesh sieve; and in practice it is generally desirable that at least 7 5 per cent shall pass a 200-mesh sieve. The mixture can be burn- .ed in any ordinary powdered fuel burner, of which many types are available, and the flame is self-sustaining under the conditions usually obtaining where such fuel burners are employed. The heat obtainable is ample for the purpose of firing oil retorts,

stills, boiler furnaces, etc, the resultant conditions in the combustion chamber into which the fuel is blown being such as to ensure continuity and smooth regulable firing fully comparable with the combustion of ordinary powdered coal While a typical example has been described in which the enriching or ash-lowering constituent is employed in actual mixture with the shale prior to combustion, the invention is to be understood as broad in scope, and in certain aspects thereof to contemplate any means of introducing into a combustion chamber the proper proportion of an enriching or ash-lowering fuel, and effecting cooperative combustion thereof in conjunction with the powdered shale blown in, whether there be actual mixture of the two fuel constituents prior to combustion or not.

What I claim is:

1. The method of preparing a fuel from bituminous shale which comprises pulverizing a mixture of such shale with solid carbonaceous matter which itself is pulverizable substantially without gumming.

2. The method of preparing a fuel from bituminous shale which comprises pulverizing a mixture of such shale with solidcarbonaceous fuel which itself is pulverizable substantially without gumming, and which has a lower ash content than the shale.

3. The method of preparing a fuel from bituminous shale which comprises grinding a mixture of such shale with a coal having an ash content below 50 per cent in such ltlll lllll proportions that the ash content of the resultant ground mixture does not substantially exceed 50 per cent.

4. In the art of fuels, the process of reducing an oil-bearing solid fuel to pulverulent condition which comprises pulverizing such solid in mixture with a solid fuel diluent which itself is combustible and readily pulverizable.

5. In the art of fuels, the process of reducing an oil-bearing solid fuel to pulverulent condition which comprises pulverizing such solid in mixture with a solid fuel diluent which itself is combustible and readily ulverizable, said diluent being employe in such proportion that the resultant pulverized mixture passes readily through fine screens.

6. As a new fuel, a pulverulent combustible comprising bituminous shale and additional combustible material of lower ash content.

7. As a new fuel, a pulverulent combustible comprising bitumlnous shale and additional combustible material of lower ash content, the combination containing not more than about 50 per cent ash.

8. As a new fuel, a pulverulent combustible comprising bituminous shale and addi tional combustible material of lower ash content, the combination containing not more volatile matter, and at least 75 per cent of said mixture being fine enough to pass a 200 mesh sieve.

10. As a new fuel, a finely powdered combustible mixture comprising bituminous solid matter analyzing 25 to 40 per cent combustible matter and above per cent ash, enriched with enough of another solid combustible of less than 50 per cent ash, to bring the ash content of the mixture below 50 per cent.

11. As a new fuel, a pulverulent combustible comprising an intimate mixture of bituminous shale and-a carbonaceous enriching material in finely divided condition.

In testimony whereof I hereunto afl'lx my signature.

WILLIAM HUNTLEY HAMPTON. I