US2136591A - Method for manufacture of compound agglomerate containing fuel - Google Patents

Description

R. G. M'dOPHERSON 2,136,591

Filed March 9, 1956 2 Sheets-Sheet 1 Nov. 15, 1938.

METHOD FOR MANUFACTURE OF COMPOUND AGGLOMERATE CONTAINING FUEL Inveaafor: a. Maol'oaehsom Noir. 15, 1938. R. G. MWPHERSON METHOD FOR MANUFACTURE OF COMPOUNDAGGLOMERATE CONTAINI [NG FUEL Filed March 9, 1956 2 Sheets-Sheet 2 .13708325173: Boy $.Maolizezagon; y r

PatentedNov. 15, 1938 UNITED STATES METHOD For: mmacruns or conromp AGGLOMERATE coxrammo Roy G. Macl'her'son, Framinghan Mus. Application March 9, 1936, Serial No. 67,774 4' Claims. (01. 44-10) This invention relates generally to the art of fuel production, and more specifically to a novel and improved process and apparatus for making at low coking temperature an anthracitic com- 5 pounded fuel, primarily for domestic use, or the making of gas. The process is useful also for making agglomerates for use in metallurgical and other fields.

The domestic users of coal require preferably a free but steady burning fuel, that is free from dust and gives off but little 'smoke. Without question, properly prepared anthracite coal is the nearest approach now available to an ideal fuel for that purpose, but the commercial supply of sizes larger than silt or fines is relatively limited, and expensive.

Soft coal,of which there is an unlimited supply of varying qualities, at reasonable prices, is well adapted for steam making and kindred purposes on a large scale, but not for household use, be-

cause it lacks the qualities already recited as desirable for that purpose. of fine sizes of both kindsof coal there is an immense'quantity that cannot be used satisfactorily for domestic purposes.

Many attempts have been made to make an agglomerate or compound coal, so-called, of anthracite and bituminous fines, or slack, both separately and together, and with and without other materials, compressed with a bonding material of some kind, and in the form of briquettes, or J ovoids. Such coals or fuel have some merits, but the art has never been commercially very successful. Coke made from soft coal of various kinds has long been used, but such coke usually has been the by-product of processes for distilling gases of various kinds, at high temperature, and the coke has therefore been porous, quite low in volatilecontent, and not entirely satisfactory for '40 domestic use, as might be expected. Coke for domestic use should be dense in structure, and free burning.

. While most bituminous coals will make a dense coke, if heated slowly, it has been found prac- 45 tically impossible to convert any natural bituminous coal alone into a dense, low temperature coke-like fuel immediately and rapidly. But I have discovered that a properly prepared mixture of bituminous coal and other materials or ele- 50 ments can be quickly and satisfactorily treated by my novel method, and thereby produce a novel fuel. So far as I have been able to ascertain, all commercialsoft coals are too rich in volatile content to be handled directly. They need to be '55 diluted with less volatile solid material,

The diluting agent may be a burnable material, as anthracite fines, or coke breeze,'or semi-coke made for the purpose. or it may even be incombustible material, such as lime,.ores, or even common sand. 6

While much time and effort have been expended in the attempt to make a satisfactory product for domestic use, from soft coal, I am convinced that one or more elements besides the soft coal are needed for satisfactory production. 10

The best material to be used in any given case will be determine by the particular use for which the product is to made, and the availability of the supply of these materials.

A mixture of soft coal and anthracite fines, or 5 crushed lump anthracite, with a suitable binder,

treated primarily for fuel'andnot for distillation of other products, makes a very satisfactory, free a and long burning material for domestic use.

Many materials may be used as binders, and 20 their'character may affect materially the resulting product. Bunker oil, starch solutions, even water, have been used. A thin tar, obtained as by low temperature coking, is a. satisfactory binder. I

A heavy coal tar usually 'facilitates the blending power of a compound, and decreases the amount of bituminous coal to be used.

Molding of the mixture in some form is desir-' able in the making of domestic fuel, as it increases 30 the compactness of the original mixture, and renders it more convenient for subsequent treatment. Accordingly, the present invention is directed to the production of an improved, novel compound fuel, by a novel process and apparatus. 35

In the drawings of one embodiment of my novel apparatus for carrying out my improved process described and illustrated herein:

Fig. 1 is a longitudinal section, with parts in elevation, of one embodiment thereof 40 Fig. 2, a vertical cross section on line 2-2 of 1, looking toward the right; and Figs. 3 and 4, modified forms, respectively, of

the apparatus shown in Fig. 1.

I first mix my materials in any suitable manner, the proportions of the various ingredients depending upon the character of thevarious individual materials used and. the type of product desired. Anthracite fines is inexpensive and readily obtainable, and yard screenings are very satisfactory for use with bituminous coal. I prefer that the dry ingredients shall be ground or classified to pass a l0 mesh screen.

When anthracite silt is used with the soft coal, the liner the anthracite silt the greater the pers5 centage of soft coal that must be used within practical limits. For example, I have found that 30 parts of soft coal and '70 parts of yard screenings, as usually-obtained locally, with 8 parts of light tar, all by volume, made a satisfactory combination. These proportions, however, will vary accord ng to the degree of fineness of the materials and the kind of tar used. 1

After mixing the material A, Fig. 1, it is preferably fed to an endless-conveyor l, travelling on a driving roll 2 and pressure roll I, and driven from any suitable means, not shown. I have discovered that there is a distinct advantage in treating my product in the form of a ribbo or elongated sheet. The cost of manufacture is relatively low, and the process may be substantially continuous. l

Immediately above and cooperating with the roll I is a second pressure roll l, mounted adjustably to vary the amount of pressure as desired, and controlling the thickness of the ribbon of material passing through the rolls.

. The conveyor delivers the mixture upon a table 5, suitably secured, as by securing its flanged ends 6 to the end walls of a retort, or closed chamber I, with a non-oxidizing atmosphere around the material, and of kettle iron, chrome iron, or other suitable material, and of proper length,s'ay20to30feet.

The retort is properly housed in a prick or other setting l, with a front wall 0, fire arch II, baiiies II, as needed. and rear wall i2, forming a combustion chamber with a flue-|2a leading to' a chimney, not shown. The retort housing is provided with ports ii for supplying fuel gas, also a nozzle II for gas,.if desired, and again may have an oil burner II of convenient type and size, or the combustion chamber may be heated in any of the ways of engineering practice. 7

This retort has, at its rear end, a downwardly inclined chute II, or discharge passage, leading to a combined storage and curing hopper ll, or

other receptacle, suitably supported, with one or more outlets I! for drawing of! any gaseous products or vapor, and "at the hopper's lower end, it

- has a discharge outlet 2!, provided with any suitable valve for substantially excluding the air from the hopper l8. This valve may be a cone-shaped element 2|, operated by a rod extended through the hopper top, and pivoted on a post 24, and provided with a weight or other means for causing the valve to remain normally closed.

The hopper I. may discharge into a second similar hopper 25, also closed by a suitable valve 26, conveniently controlled, as by a lever 21, the purpose being ordinarily not to have more than one of these valves 2| or 28 open at the same time.

It has been proposed, among other methods, to extrude a coal compound or mixture under pressure through a tube subjected to substantially a coking temperature, so that the extruded compound would be coked when discharged. This plan, however, has many disadvantages and diillculties. It has been found by experience diflicult to cause the molded compound to flow and ex-' trude continuously without frequent interruption, thus causing shut-downs'of the machine.

Briquettes have been made and carbonized, but this process is expensive and diflicult; it requires means to produce tremendous pressure, and it is diflicult to maintain an airtight seal to the retort while feeding the briquettes to it, and it is exceedingly hard to apply a proper temperature to the briquettes, as they disintegrate with applicaon of high heat, and again because, atcoking temperatures they will fuse together, unless well separated. Unless they can be so treated, they make an inferior fuel, as compared to my novel product, as theywill'dislntegrate on the fire before they are consumed, and burn with a smoky flame. I have discovered that by compressing the material into a wide ribbon, or into an essentially continuous sheet of desired width, bonded to hold its shape until the exterior surface sears over fsufllciently to ensure its final form, and then treating it at so-called low temperature of approximately 1400 to 1600 F.. it is cheaper, and far more satisfactory as a compound fuel than any that I know of.

The material, Fig. 1, atter passing between the compressing rolls onto the plate 5, is deposited upon a suitable endless conveyor 28, as a woven wire belt on rollers t l, suitably driven as by an exterior drive belt II, from and by driving elements not shown. The belt 2! may travel overidlers 32, if desirable for support.

As the material is fed to the plate 5, after being compressed to a suitable thickness, say one to two inches, a hinged, or spring, cover 33 presses lightly thereon, to help keep it from buckling, if so inclined, and to practically prevent the ingress of air to the retort, and the material then passes through the retort I, which is properly heated,

sayto about 1400 I. As the sheet of material approaches the forward end of the retort, a star wheel 34, driven by any means, not shown, or any other convenient device, may mark and crease the sheet regularly to an extent suillcient to help cause the sheet to break into pieces of fairly 1miform size, as they drop into thehopper It, or in subsequent handling. h

By closing the valve 28, and discharging the fuel into the hopper 25 through valve 2|, only a minimum amount of air will be admitted to the hopper l8 and retort By closing the valve.2|

and opening the valve. 26,'the iuel may be discharged from the hopper 25 into a car or other receptacle, without admitting morethan a small quantity of air through the valve 2|.

The cycle of operation of valves- 2| and 26 may -be regulated to suit the manufacturing conditions. v

- With temperature of approximately 1400 F., the mixture should yield its volatile products to the desired extent, and in effect coke satisfactorily in about 13 to 15 minutes in the retort.

By the foregoing process, the bituminous coal .will part with some of its volatile content, and

combine with the anthracite fines to form a dense mass, and I can continuously, and at low cost, produce a dense anthracite agglomerate or compounded fuel of convenient sizedpieces, free and long burning, having a heating value essentially equivalent to that of the bestgrades of anthracite, and burning with no hard clinkers. The ash content may be regulated by the selection of suitable raw materials.

It is further to be understood that the actual arrangement of the elements of the apparatus used may be varied. For example, Fig. 3, the pressure rolls 3, 4, may be located within the retort, and kept cool, i1 desired, through the means of hollow shafts 35, carrying water or steam therethrough.

Another variation which may be used is shown in Fig. 4. wherein the material is compressed and formed into a sheet by means of a suitable press 36, operated by either toggles, cylinder and piston means 21, or otherwise, and resulting in an intermittent, yet substantially continuous feeding motion of the ribbon of material.

Reasonable variation in the length of time required for the material to travel through the retort may be accomplished by adjustment of speed of the conveyor, or by allowing the material upon discharge into the hopper I8 to remain therein and mull inits own heat for the desired time. Small quantities of air may be admitted here, or into the hopper 25, to support a partial combustion, and thus furnish additional heat for treatment, if desired.

My invention is not restricted to the particular form or embodiment of means for practising it herein shown.

I claim:

1. The process of making compounded smokeless fuel comprising mixing about ten to thirty parts of comminuted coking coal with about ninety to seventy parts of comminuted non-coking coal and enough volatile liquid lubricating medium to serve as a temporary binder without substantially changing its character as a dry mixture, compressing the mixture essentially cold to form a self-sustaining continuous strip of approximately the density of an anthracite coal product, freely supporting the compacted strip while passing it through a heating zone containing substantially no oxygen in the surrounding atmosphere at a coking temperature for a period sufficient to volatilize and coke the binder and part of the coal thereby causing the coking and non-coking coal to agglomerate in a hard dense coke-like mass having a specific gravity approximating that ofthe non-coking coal used, said mass containing suflicient volatile matter to be free burning in domestic heaters, and separating said mass into convenient size pieces for transportation and use. I v

2. A continuous process of agglomerating coking and non-coking comminuted solid material comprising mixing a smaller proportion of coking material and a larger proportion of non-cok ing material with suflicient volatile liquid to serve as a temporary binder when compacted, rolling the mixture without preheating to compress it into a self-sustaining continuous strip with a density of the order of the average of non-cokable constituents in the raw state, freely supporting the strip thus formed while conveying it through a non-oxidizing heating zone at a coking temperature for a suflicient time to volatilize the binder and sinter together the coking and noncoking material in a hard dense mass, and separating said mass into fragments of desired size.

3.'A continuous process of agglomerating coking and non-coking comminuted solid material comprising mixing a smallerproportion of coking material and a larger proportion of non-coking material with sufiicient volatile liquid to serve as a temporary binder when compacted, pressing and scoring the mixture without preheating to compress the same into a self-sustaining con tinuous strip with a density of the order of the average of non-cokable constituents in the raw state and containing depressions at regular intervals, freely supporting the strip thus formed while conveying it through a non-oxidizing heating- Zone at a coking temperature for a sufficient time to volatilize the binder and coking and non-coking material in a hard dense mass, and separating said mass into fragments along lines of fracture corresponding to said depressions.

4. A process of making a dense solid agglomerate containing carbon uniformly distributed throughout the mass, comprising mixing coking coal in lesser amount and non-coking sol d material in greater amount with a ,suflicient amount of liquid binder to hold the mixture together without changing its dry character when compacted, continuously feeding and compacting the mixture without preheating, and controlling the degree of compacting to ritain a density of product of the order of the average of the non-cokable constituents in the raw state, exposing the compacted material for a substantial length of time before coking it, conveying said material through an oxygen free atmosphere in a coking zone at a controlled rate of speed and while free from restraint subjecting it to a temperature sufficient to cause the volatilization and coking of" the binder and coking coal to form a dense solid agglomerate containing solid carbonaceous material and a sinter together the v minimum amount of volatile material suitable for charging to 'a furnace.

RO Y G. MAcPI-IERSON.

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