US1846982A - Method of converting coal - Google Patents

Description

2 Sheets-Sheet 1 Inl/671157'.

96077162716, M my Feb. 23, 1932.

n L. l. YEOMANS METHOD oF CONVERTING COAL Filed March 25, 1927 Feb. 23, 1932.

L. l. YEOMANS METHODv OF GNVERTNG COAL Filed March 23, 1927 2 Sheets-Sheet 2 'jm/@1255 Lucien yomczns Patented Feb. 23, 1932 UNITED STATES PATENToFFlcE i LUCIEN' I. YEOHANS, 0F CHICAGQILLINOIS, ASSIGNOR`TO LUCIEN' I. YEOMLAIN'S, 11T- CORPORATED, 0F CHICAGO, ILLINOISQA CORPORATION OF ILLDTOIS METHOD 0F CONVEBTING COAL Application led March 23, 1927. Serial No. 177,562.

It is probable that grades of bituminous coal which'are particularly distinguished by a low volatile content and high fixed carbon,

such as Pocahontas, were formed in naturek from high volatile coal by suitable conditions of slight pressure, moderate temperature and undisturbed conditions during ensuing exothermic reactions; and I have found that coal of high volatile content can be converted into coal of comparatively low volatile by simulating the conditions above noted.

The commercial value of such conversion is evident. Large quantities of readily gasi- 'fied constituents cause coals of that nature to burn with resultantsmoke, except under extremely favorable conditions, and it is usual to pay considerably higher prices for coal of lower volatile content which'may be tired more or less carelessly in ordinary furnaces without a resultant smoke nuisance.

It is common practice to convert such coals into coke by driving off the volatile constituents in whole or in large part by the application of high temperatures, leavin a resultant product composed largely of fixe carbon and ash. It has also been proposed, by the application of lower temperatures, to produce what is sometimes called low-temperature coke, in the resultant of which processes some part of the volatile is still retained. Lowtemperature processes, however, have not been commercially successful on any large scale. due to a failure to observethe essentials for the conversion of a coal of high volatile into a low-volatile product partaking of the characteristics of coal rather than simulating those of coke.

The essentials necessary for the conversion of high volatile coal into low volatile coal are as follows:

1. Heat must be applied throughout a mass of the coal to be treated unt-il a condition of semi-fluidity is reached, but the .ignition point of the coal must notv be attained.

In the treatment of certain Illinois coals, for

example, the mass should be heated to 390 C.

2. After the mass of coal has reached this temperature, exothermic reactions occur, gases and vapors being liberated. During this periodthe mass must be relatively quiescent, in order to avoid crumbling of the char, and a slight pressure must be maintained upon the mass to minimize the production of pores in the char, and thus insure a product having a density approximately that of coal.

3. Ample opportunity for the free escape of volatile constituents must be provided, before the coal mass becomes semi-fluid, during that stage, and afterward, all with the least restriction and necessity for travel of gases. through the mass.

The object of the present'invention is to provide a method adapted for the continuous conversion of carbonaceous material, as, for example, high-volatile coal, into low-volatile high-ixed-carbon coal, and arranged to produce the essential conditions hereinbefore mentioned. f

In the accompanying drawings, Figure 1 is an elevation of one form of apparatus which may be used in carrying out my invention.

Fig. 2 is a fragmental vertical sectional view of the form of apparatus shown in Fig. 1. l

Fig. 3 is a horizontal sectional view in the plane of line 3-3 of Fig. 2.

Fig. 4 is a section on line 4 4 of Fig. 2.

Figs5 and 6 are fragmental vertical sectional views showing modifications of the apparatus illustrated in Fig. 2.

The apparatus shown in Figs. 1 and 2 comprises an elongated cylindrical retort l preferably arranged in verticalposition. The length of the retort 1 is determined, in part, by the rate at which it is desired to move material through the retort, by the time required to initiate and complete the exothermic reaction and to permit setting of the product resulting from such reaction, and by the pressure to be produced by the weight of the column of material. In order that the material under treatment shall be heated as uniformly as practicable, it is desirable that the retort be of relatively small diameter, thus minimizing the distance through which heat must penetrate from the retort wall to the inner portion of the charge.

. Any suitable means may be provided for heatin the retort throughout all or aporntion o its length. Herein is shown a casing the retort 1 at the desired temperature. The bath of molten material surrounding the retort prevents the retort from being excessively heated at any point. In practice, a, pluralit of retorts 1 would preferably be enclose within a furnace of any desired character. L'

Means is provided at the lowerend of the retort for forcing coal up through the retort. Preferably the coal-moving means is of such character as to produce continuous or substantially continuous movement of the mass under treatment. Herein is shown a casing 5 containing a screw conveyor 6 alined with and of the same diameter as the retort. 7 is a conduit leading from a suitable source of vsupply of crushed coal to the lower portion of the chamber containing the screw conveyor. If desired, the screw conveyor 6 may be of such form as to compress the coal as the latter is advanced-to the retort. Herein the shaft of the screw -is shown as decreas. ing regularly in diameter, and the spiral of the screw as gradually decreasing in pitch, from.the inlet to the dischargeend of theconveyor. Y

The screw 'conveyor 6 is shownas driven by means including a shaft 8, reduction gear ing 9 and a drive shaft 10, although it will be understood that any desired means may be provided for this purpose.-

The upper end of the retort communicates with a casing 11 which provides a connection 12 for a conduit through which gas and vapor are exhausted, and an outlet 13 for the converted coal. The wall 14 of the casing 11 is curved or inclined so as to extend across the path of movement of the solid product emerging from the retort, whereby the upper end of thecolumn of material is frac tured, the pieces broken oif being discharged by gravity through`the outlet 13.

In order that the char shall be relatively dense, it is important that the escape of gas and vapor during the period when the coal is plastic and is setting befacilitated as much as possible. To attain othis result I provide a shaft 15 disposed axially of the retort 1 and rotated by any preferre means, as, for exf ample, by being attached to the discharge end of the screw conveyor 6. The length of the shaft 15 may var`y in accordance with the` conditions met in practice; with some coals it may terminate a short distance after it enters the mass; with other coals it should preferably extend through the region in which the char is settin That portion of the shaft which exten upwardly from the re gion where gases and vapors are liberated in considerable quantities is preferably of noncircular cross-section, as indicated in Fig. 3,- so asvto provide inits rotation a passage or vent for the gases and vapors. v

In use the carbonaceous material to be treated, as,for example, c oal of high volatile content preferably crushed to comparative ineness, is conducted through the conduit 7 to the screw conveyor 6. As it is carried along by the screw it is packed orlsomewhat compressed. After leaving the screw the material is forced upwardly through the retort by the thrust ofthe screw propelling succeeding masses of raw coal against it. By

the rotation of the screw conveyor and the extended shaft l5 a space in the center of the moving column of raw coal is-kept free from coal, and when the portion of the shaft 15 which is round in cross-section has been passed, this space constitutes a passage for the escape ofovapors and gases and thus pro- Vides for their egress from the apparatus with the shortest possible travel through the mass being treated. As hereinbefore stated, the retort 1 is of relatively small diameter in order that the gases and vapors shall be obliged to pass through only a thin layer of material to'reach the central gas passage.

The weight of. the mass and the frictimi against the retort walls may be relied upon to cause resistance to the travel of the mass, resulting in the establishment of slight pressure which is most effective in the plastic zone, thus-preventing the liberation of the gases and vapors from imparting porosity x to the char.

If in treating certain varieties -of coal it should be desirable to increasea the pressure )beyond that resulting from the wei ht of the column and the friction upon t e retort walls, the retort may be made, to taper inwardly slightlyl from its lower end as far as the need for such increased pressure exists, as indicated at 1a in Fig. 6. If desired, the remainder of the retort may taper. outwardly y towald its upper end, as mdicated at 1b in If the coal to be treated swells considerably during carbonization, it may be desirable to construct the retort so that it increases in diameter from its lower to its upper end, as

indicated at 1 in Fig. 5.

. Althou h the mass is moving continuously through t e retort, no substantial agitation occurs, the particles of the mass being practically at rest with relation to each other.

Hence practically no breeze is produced.

Bymy improved method herein disclosedf y coal Ccontaining approximately 35% volatile from the deposits of southern Illinois may be converted into a coalrtproduct with a. specific gravity, volatile co ent and fixed carbon resembling that insuch coals as Pocahontas.

" While I have described the method as.

adapted for the carboni/zation of coal, it may p v y. t

les

be Yuseful the treatment of other mate` rials.

In the following claim, the term continuous is intended to include intermittent movement consisting of steps which. are so short and frequent that the motion, for all practical purposes, is`continuous.v

' I claim as my invention z. A Y A continuous method of converting cr ed bituminous coal having a specific gravity less than that of Pocahontas coal into a fuelhaving a specific gravity and volatile content yapproximating ythat of Pocahontas coa1,v which consists in forcing a quantity of said crushed bituminous coal arranged in the form of a hollow cylinder upwardly throughga reytort by pressure exerted only at the lower portion of the column, the axis of the cylinv der being @long the direction of movement of the material, uniformly heating the retort only to the degree necessary to vinitiate exo- ;'thermic reaction in the coal, the path of travel of the 'material being of sutlicient length so that fusion and setting occur prior to discharge from the retort, and so that the weight of the column of material after setting shall produce suiiicientfcontinuous' pressure upon the plastic material to make' the char of a density approximating that of Pocahontas coal and greater than that ofthe coal being treated, withdrawing the vapors and, gases upwardl within the cylinder of material, and discharging the char from the retort imv mediately-after the recited `heating andsetting.

In testimony whereof have hereunto af-

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