US1950017A - Method of carbonizing coal briquettes - Google Patents

Description

March 6, 1934. E. B. A. zwoYER Er Al. l1,950,017

METHOD OF CARBONIZING COAL BRIQUETTES vFiled Aug. 11, 1931 2 sheets-sheet 1 Q EL? N m S m N T. W

2 Sheets-Sheet 2 R0 TARY CARBBNIZER BRlquErTes l COOLER Filed Aug.

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CUAL HEATER /zze E. B. A. ZWOYER E1' AL METHOD oF CARBONIZING COAL BRIQUETTES BRnQuErTEs wer COAL AND March 6, 1934.

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i M TW R T 0R. WE M B aan method of treatment which Patented Mar. 6, 1934 T OFFICE METHOD F CRBONIZING iC'OAL VBRIQUE'IJTES Ellsworth B. A. ZwcyenPerth Amboy, and Albert L. Stillman, Plainfield, N. J., yassignors to The' General Fuel Briquette Corporation, New York,

N. Y., a. corporation of New York Application August 11, 1931, Serial No. 556,378

7 Claims.

r1`his invention relates to a method for producingsmokeless fuel briquettes possessing sufficient rigidity of structure, not only during the several stages of treatment, but to withstand handling,

transportation and maintain their form after ignition and while being consumed.

The type of briquettes with which the process is more particularly concerned involves the use of finely ground anthracite and a binder of Coal tar pitch or sulphite pitch and molasses. The method of mixing proportioning, handling and briquetting this type of material is well known, but the briquettes as delivered by the briquettng press do not possess the necessary strength and rigidity for ordinary use nor are they smokeless. I-Ieretofore efforts have been made to render-such briquettes smokeless by exposing them to elevated temperatures, but the uidity of the binders during the heat treatment, the movement of the briquettes in their heat softened condition upon each other, and similar conditions interferred with the successful commercial use of such process on any substantial scale. It is one of the objects of the present invention to supply a will be economical throughout and in which the briquettes will be subjected to a series of treatments each appropriate for the then particular condition ofthe briquettes.

The invention is illustrated in thegdrawings in which Fig. 1 illustrates a longitudinal section through the apparatus and Fig.`2 is a plan View of the apparatus shown in Fig. 1.

The temperature gures applied to these lig- Aures of the drawings are representative of conditions prevailing in one method of practicing the invention. Fig. 3 is a diagrammatic elevational view looking at the briquette conveyor from the left side of Figs. `1 and 2. Fig. 4 is a similar View of a coal fines conveyor viewed from vthe right side of Figs. 1 and 2, and Fig. 5 is a similar viewk illustrating the operations of the coal fines conveyor 22 viewed from the right side of Figs. 1 and 2.

In connection with these drawings vit-is' to be presupposed that briquettes composed of about i-94% anthracite particles and 640% binder constituted of coal tar and'bunker C fuelv oil or other suitable binding material such for example as sulphite pitch and molasses and shaped and compressed in a press such as that shown in United States lfratentNo. 1,627,222, are being delivered withmachine like regularity to a drag chain conveyor l. The briquettes are con-- -veyed by this-conveyor from the press to-the'preheater chamber 2 and reach the preheaten'while still retaining a vtenfiperature of approximately 150 remaining from the press temperature. The bottom of the conveyor trough consists of a gate Vextending over the entire'wdth of the chain grate 3 in the preheating chamber 2. The design of the gate is such thatit may be adjusted to any angle necessary to cause'the briquettes to be deposited upon the chain grate 3 as a quiescent single layer in which the individual brquettes are substantially out of pressure Contact with one another.

The chain grate 3 is endless andY acts as a conveyor on which the uncarbonizedbriquettes are distributed in asingle layer so that each may receive like treatment. The use of a standard make of roller chain 4 acting as a roller bearing, interposedbetween the chain grate and the supporting track 5, represents a markedimprovement over other structures heretofore suggested for performing analogous service. The speed-of the chain grate is such that each individual briquette will remain in the chamber 2 fora period ranging from 2 to 5 minutes depending upon the particular Vkindof briquettes andthe variation of temperature conditions. ,Y ,f

For the heat treatment of the briquettea; a Stoker fired furnace 6 furnishes suiiicient heat of suicient uniformity for the entire carbcnizing operation to which the briquettes are subjected in their passage through Vthe entire apparatus, shownin the drawings, from thepoint ofintroduction to the point of their discharge.

The temperature ofthe incoming gases passing from the furnace 6 and passing into Contact with `thesingle layer of briquettes, in the preheater chamber 2, is approximately 2000 F.V This approximate temperature is readily maintainable by the employment of a kthermostatic furnace control (not shown). As the temperature of the briquettes is'about 150 F. it is apparent that, as they enter the preheater 2, they Will-at once` be exposedto the greatest difference intemperature and the highest temperature vof the entire process. The result of this treatment is to quickly surface harden the briquettes uniformly over their entire surface to the end that they maybe successfully passed through the next succeeding operation notwithstanding thattheinner portions of the briquettes are still in a soft condition. This effect is most effectively accom-v plished by individualizing the brique'tte'sjon the chain grate for 'if they werein pressure contact' with one another or rested one upon the other .as theydoon the cross conveyor 1,"the heat would time to absorb the necessary heat from the furnot envelop the briquet-tes uniformly and they would be soft and misshapen at their points of compressive contact.

The temperature of the briquettes leaving the preheater 2 is approximately 950 F. while the temperature of the furnace gases leaving the preheater 2 is about 1200 to 14=00 F. say 1300 F. for example, at the inlet end of the rotary carbonizer 7. The rotary carbonizer '7 may be a tube approximately four feet in diameter arranged to be slowly revolved by mechanism (not shown) at a rate of about 1/4 R. P. M. In this rotary drum 'l the briduettes are rolled on`each other that is, subjected in a mass to a slow tumbling action, being in this way uniformly exposed to the high temperature furnace gases, until at the discharge end of the rotary drum 7 the carbonizing gases are approximately 800 F. while the temperature of the briquettes is about l700. The rotary drum l is inclined so that the rotation of the drum causes the briquettes to travellengthwise thereof while being gently agi tated together in a rotary motion and the inclination is such that the briquettes are maintained in the drum for about 15 minutes, or sufcient nace gases.' The degree of inclination of the drum 7 can be varied to lengthenor shorten the time for the brquettes to pass through the carbonizer drum 7 according to the particular nature and constitution of the briquettes. In any event care is taken at the elevated end of the drum "I that a tight t is provided, with the end of the preheater 2, to prevent leakage of the furnace gases and the entry of oxidizing air and temperature loss at this point. An inclined wall 8 provides a smooth, connecting guideway for the briquettes between the time they leave the chain grate 3 and their entry into `the drum 7.

If desired the preheater may be wider than shown in the drawing and a plurality of drums may be used.

The operative rotating speed of the drum 'lis made extremely low in order to eliminate the abrasive action on the briquettes, otherwise occurring in this part ofthe apparatus. If in connection with the particular type of briquettes, too much abrasion should manifest itself, the speed of rotation is reduced and the inclination increased.

After the briquettes have passed through the drum '7 they have been almost completely carbonized and therefore rendered smokeless and by reason of the antecedent series of steps their Vshape has been vpreserved and their strength greatly increased. In order, however, to store the briquettes safely it is important that their temperature should be reduced to approximately 150. F. throughout 100% of the entire mass. In other words'a vcooling system must be provided which will reliably reduce the temperature to the stated point. Without such temperature reduction at any point, the briquettes otherwise, when stored, are likely to catch afire.

below the critical point, is manifestly undesirable for many reasons. Atmospheric or forced air cooling are expensive in operation and uncertain.

To meet 'the necessary conditions, the procedureV -now to be described was devised and found to into intimate uniform contact with coal fines, from their place of storage, on their way to the mixer Quenching with water, lwhile very effective as a temperature reducer to from which the briquetting press draws its supply. Such coal fines are naturally moist depending somewhat upon humidity, precipitation, length of time of storage, etc. At any rate they can be depended upon to have a moisture content of at least 15%. These moist coal fines are fed into the conveyor 10 by the conveyor 9 from an outside sourceof supply. The conveyor 10 passes below the discharge end of the carbonizing drum 'l and there receives the hot briquettes as they are discharged from the drum '7. The conveyor i0 is in the form of a gravity discharge bucket elevator, which retains the briquettes and the coal fines, which have been deposited upon the briduettes from the conveyor 9, until they reach the chute aperture 11 where they are dumped indiscriminately into said chute 1l' and thence into the ele vated end of the cooling unit 12. The nature and action or" the conveyors 9 and 10 are of standard and well known type. One available varietyis illustrated in Fig. 3 where the chains 10a carry buckets 10b, which, moving over plate 10c, pick up the briquettes and subsequently the coal nes deposited on said plate by a scraper conveyor 9. The buckets 10b, on passing over the roller 10d, deposit their contents on the plate 10e and also advance the mixed briquettes and fines into the chute 11. In the cooler 12 the wet coal and hot briquettes are now caused to intermingle thoroughly with each other by the rotary action of the cooler unit 12. Moisture `evaporated from the coal nes, by the heat of the briquettes, being carried away by the current of air passing counter current through the cooler 12 into the stack housing 13.` The lower end-of the cooler 12 comprises a separating chamber inthe form ofY a screen 14, through which the dried heated fines are discharged into the gravity discharge bucket elevator 15, while the briquettes substantially free from' the screened fines, and now having a uniform temperature of approximately 130 F., slide over the spout 16 into suitable vehicles or conveyors by which they are brought to storage, or shipped.

The'iines discharged into the elevator 15 which, as illustrated in Fig. f1, operates like the conveyor 10, comprising chains 15a carrying buckets 15b, plate 15c,`and plate 15e are discharged into the chute 17, which leads to the elevated end of a rotary conditioning unit 18, through which in the opposite direction pass the furnace gases, from the furnace 6 after they have done their work in the preheater 2 and inthe carbonizer drum 7, and where they still have a temperature of about 800 F. The coal rines entering unit 18, have a temperature of about .130 F., will be raised to about 250 F. as they pass through unit 18, while the exhaust gases from the drum '7, entering unit 13 at about 800 F. are discharged into the stack 19 at approximately 30D-400 F. Fans 20 and 21 maintain the proper draft requirements at the two stacks of the apparatus.

The'binders used for briquettes have a melting coal fines with which they are to amalgamate thereby effecting considerable economy in their partY of the operation. The hot coal nes distransported by the bucket elevator 22 illustrated I J plate 22e, upper plate 22e, said plate 22e having its delivery point directly anterior to the mixer, or to a place of storage in the vicinity of the mixer, so that they can be used before they have lost their heat. The feed of coal fines into the conveyor l0 can be regulated in consonance with the amount required in the mixer to keep the briquetting press supplied with mixed material at the rate at which the press delivers `briqluetted product to the conveyor 1. It" will be noted, that proceeding in this manner, there will be'ample moist coal fines fed to the hot briquettes entering the cooler 12 to effect the necessary cooling of the briquettes in that unit. When starting operations after a shut down, or new installation, heat is started in furnace 6, coal fines are fed into the elevated end of unit 18 or conveyed thereif desired by elevators 9 and 10, unit 12 and elevator 1 5, the fines being in this way preheated for the mixing operation. After suflicient amounts of hot fines have been mixed with the binder to start supplying the press for continuous operation, the press begins its work, delivering its product to conveyor 1 and in a very short time the entire apparatus shown in the drawings will function automatically and normally in the manner hereinabove described.

The process hereinabove described lends itself to the production of satisfactory briquettes in which the binders may be of various kinds including such as contain asphaltic oil or asphalt coal tar and bunker C fuel oil or bunker C fuel oil alone. In fact so far as the use of a binder composed of bunker C fuel oil is concerned, the process hereinabove described is, so far as we are aware, the only known process by which satis- .factory briquettes can be produced when that type of binder is employed. The initial high temperature treatment seems to cause reactions which leave an effective condition of cohesion in the briquettes even in those cases where asphaltic binders or similar binders, which ordinarily possess only an inferior binding capacity, are used. Thus the new process opens up elds of use for binder materials which have not thus far been usable with satisfactory effect in commercial practice.

The process described herein is particularly advantageous when used in connection with anthracite briquettes but may, of course, be employed in connection with material equivalent to anthracite in its behaviour in relation to and in response to the said process. When, therefore, in the claims we refer to anthracite coal, it is to be understood that we include equivalent material.

We claim:

1. The method of making coal briquettes, which comprises distributing raw compressed briquettes, composed of inely ground anthracite coal and a binder, as a single layer within a heating cham- Zher and passing them through said heating chamber as a quiescent single layer in whichtheindividual briouettes are substantially not in pressure contact with one another, subjecting said briquettes forthwith upon their entry into said chamber to high heat, maintaining said briquettes said high heat region for a sumcient time to surface harden said briquettes 'out not long enough to result in combustion or to carbonize them throughout, then in a separate stage carbonizing lthe criquettes at a lower temperature appropriate for thoroughlycarbonizing such briquettes and simultaneously subjecting said briquettes in a briquet-tes roll upon each other, and nnally cooling the thus hardened and carbonized briquettes.

2. In a method of making coal briquettes containing particles of anthracite coal, the steps which comprise mixing the coal with a binder, molding carbonizable briquettes therefrom, subjecting such briquettes as a quiescent single layer in which the individual briquettes are substantially out of pressure contact with one another to a high heat for a short period to surface-harden them without carbonizing `them throughout, withdrawing the briquettes from the zone of high heat, and thereupon in a separate stage subjecting said briquettes in a mass to a slow tumbling action so that the briquettes roll upon each other l and during said stage carbonizing the briquettes at a lower temperature appropriate for thoroughly carbonizing such briquettes.

3. In the method of making coal briquettes containing particles of anthracite coal, the steps which comprise mixing the coal with a binder, molding carbonizable lbriquettes therefrom, subjecting such briquettes as a quiescent single layer in which the individual briquettes are substantially out of pressure contact with one another, to a high heat for a short period suilicient to merely surface-harden them, withdrawing the briquettes from the influence of high heat, then carbonizing` the briquettes throughout at a lower temperature appropriate for such carbonizing of said briquettes while gently agitating them together in a rotary motion, and subjecting the thus carbonized briquettes to a cooling medium consisting of coal iines until the temperature of the carbonized briquettes is below approximately 150 F.

4. In the method of making coal briquettes containing particles of anthracite coal, the steps which comprise mixing the coal with a binder,

molding carbonizable briquettes therefrom, subjecting such briquettes as a quiescent single layer in which the individual briquettes are substantially out of pressure contact with one another, to a high heat for a short period sufficient to merely surface-harden them, withdrawing the briquettes from the influence of high heat, then carbonizing the briquettes throughout at a lower temperature appropriate for such carbonizing of l said briquettes while gently agitating them together in a rotary motion, bringing the thus carbonized briquettes into intimate contact with a cooling medium consisting of coal fines, having a temperature materially below the temperature of the briquettes, moving the briquettes `and coal fines together in contact with each other until the coal nes have materially reduced the temperature of the briquettes, and separating the coal rines and briquettes.

5. The method of making coal briquettes containing particles of anthracite coal, which oomprises mixing the coal with a binder, molding carbonizable briquettes therefrom, arranging such briquettes in a heating space as a quiescent single layer in which the individual briquettes are substantially out of pressure contact with one another bringing high temperature combustion gases into contact with the briquettes, moving the briquettes to said carbonzing space into contact with said briquettes to carbonize the same throughout While gently agitating them together in a rotary motion, bringing the thus carbonized briquettes into heat-exchange relation with coal nes, and separating the briqnettes and coal fines.

6. In the method of making coal briquettes containing particles of anthracite coal, the steps which comprise mixing the coal with a binder, molding carbonizable oriquettes therefrom, subjecting such briquettes as a quiescent single layer in which the individual briquettes are substantially out of pressure Contact with one another to a high temperature for approximately from two to five minutes to merely surface-harden them, withdrawing the briquettesl from the influence of high heat, and subjecting` the briquettes while gently agitating them together in a rotary motion to lower temperature for approximately iiiteen minutes to carhonize them throughout.A

7. In a method of making coal briquettes containing particles of anthracite coal, the steps which comprise mixing the coal with a binder,

molding carbonizable briquettes therefrom, subjecting such brquettes as a quiescent single layer in which the individual briquettes are substantially out of pressure contact with one another to a high heat for a short period sufcient to merely surface-harden them, withdrawing the briquettes from the influence of high beat, then subjecting the briquettes While gently agitating them together in a rotary motion to a lower temperature Vto carbonize the same throughout, bringing the thus carhonized briquettes into intimate Contact with moist coal iines, having a temperature materially below the temperature of the briquettes, retaining the briquettes and coal nes'in contact With each other until the coalV ELLSWORTH B. A. ZWOYER.Y ALBERT L. s'rIIiLiviAN.V

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