US1787593A - Apparatus for preparing pulverized fuel for combustion - Google Patents

Description

Jan. 6, 1931. E. H. PEABODY APPARATUS FOR PREPARING 'PULVERIZED FUEL FOR COMBUSTION Filed May 24, 1927 fly. 4

gawk/W INVENTOR.

latented Jan. 6 1931 7 UNITED, srmcs mmmxomcn nmvnsr urnanoni, or anwibnz, N. Y.

, APPARATUS n03 rnnrnnrnerunvnnrznn run]; non comnusiiron Application filed Ma 24; 1927. Serial No. 193,869.

the grinding of the fuel so that a relatively. large percentage of it will pass through a 200 mesh screen. In the circulating and indirect systems the pulverized fuel .is trans-f ported to storage bins from which it is 'conveyed through large mains around the plant, compressed an or mechanical means or by to the point of consumption. In .the unit system the pulverizer'is placed near the furnace and thepulverized fuel delivered directly to'the furnace or into a small bin,"to provide a-reserve supply, from which it is distributedby an air blast, carrier air, to the burners.

system employed, secure a substantially: uniform distribution of the pulverized fuel throughout the mass as it is delivered to the burners. Moreover, it is of the utmost importance to insure an equalsupply of fuel to'each burner where a number of burners are installed in a furnace. If the pulverizer prepares fuel-for more than one burner it is necessary to divide the single column of air leaving the pul- Whatever the verizer and carrying; the total supply o-ffuel, into a plurality of streams supplying theindividual burners. This would be a simplematterjif the column of'carrier air 40 supporting the pulverized coal, as regards the fuel mixture, was of a homogeneous or ba lanced character and remained soduring its travel to'the burners. .A condition of uniform mixture, however, does not obtain in actual practice, and, furthermore, any. bend;

known as the the difliculty has been to.

I may be or alteration of direction of the pipe leading tothe burners has a tendency to cause the particles of pulverized fuelzto group themselves unequally in the stream of air.

In carrying out my invention I receive the stream of carrier air and pulverized fuel, in no matter what degree of unevenness of mlxture, and so treat the same as it passes through a distributor as to produce a homogeneous or balanced'mixture of the fueland air, and? so that whatever the'number of branch pipes leading from the distributor,

each will carry substantially the same pro portion of fuel. 7 v In the accompanying drawings I have shown apparatus adapted to carry out the presentinvention and in whichFig. 1 is a vertical section on the plane of the line 1-'1, Fig. 2'; Fig.2is a top view of the distributor; Fig. Bis a transverse section on the. plane of the line 3,3, Fig. 1; Fig. 4: is a transverse, section on-the plane of the line H, Fig. 1; Fig. 5 is a top view and Fig. 6 is a side view of a modified form of distributor;,Fig. 7 is a diagrammatic illustration showing the'unequal or unbalanced distribution of pulverized fuel in a column of carrier air, and Fig. 8 is a diagrammatic'ih lustration showing the uniform or balanced distribution of the fuel in the air, or the result which is sought to be accomplished by the present invention. 7

Various forms of apparatus may be employed for my intended purpose, that illustrated in Figs. 1 to 4' having been found efficient. In these figures, the numeral 1 designates a pipe, preferably Vertical, leading from any well known form of pulverizer, not shown. Secured to pipe 1, and preferably in axial alignment therewith, is a cylindrical member2 in the chamber 3 of which the redistribution or balancing. of the fuel in the carrier air is effected. The parts ,1 and 2 secured together by any suitable means, as by boltsthrougli openings in the flange 2 passing through similar openings V secured in openings in the wall of the member 4.

Interposed between the flanges of the members 1 and 2, as shown in Fig. 1, is a grid-like member '1'- having arms .8. extending from a central hub 9. This hub forms a bearing for the lower end of a shaft 10. In the opening in the bearing 9 is placed a felt ring 11, or other suitable packing to prevent particles of fuel working into the bearing. 'One of the arms 8 of the g'rid 7 is formed'with a pas-,

,sage 12 leading to a Chamber 13, below the endof the shaft. A pipe 14 connects with the outeren'd of passage 12 to which is attached agrease box from which a suitable lubricant may be fed to the chamber 13. The upper end of'shaft 10 extends through a suitable stufling box 10 and is supported upon ball bearings, not shown located near its top outside of member 4'. The shaft is rotated by any suitable means, also not shown. That part of shaft 10 within the chambers" 3 and 5' is preferably square in cross section,- as shown-in Fig. 3,'and has attached to it by suitable means, a plurality of 'blades,fourbeing shown, designated by the numeralslii,

16, 17 and 18, In an apparatus built by me, these blades are approximately 4%" wide and 24" long. It'is obvious, however,ithat they may vary in number and in dimensions, according to the particularinstallation made. The blades extend from immediately above the opening frompipe 1 into chamber 3, to the upper or discharge end of said chamber.' They divide the chamber 3 into a plurality of compartments, four in the present instance, which, for convenience of description,-may

" be designated by the letters A, B, "G and'DQ I j At its" upper end, within the chamber 5, the shaft 10 carries a'pIate Q, he purpose of 1 balanced asto the density of'mixture'.

which is to divert any particles of pulverized fuel which mayrise to the top of eham;

her 5 and throw them back into the streams passing through the distributor pipes 6, thus preventing small particles of fuel getting into the stuffing box 10'.

" In operation, the column of carrier air and fuehas the fuel is delivered from the pul verizer through pipe 1, is, in practice, nu-- that is meant, that the fuel is not evenly di tributed through the air and has the appearance, as well as it may be illustrated, as shown in Fig. 7. If permitted to flow from chamber 5 in that condition there would obviously be an unequal distribution of the fuel tothe several burners. Itis therefore the function of the blades asthey are rotated in chamber 3 over the outlet of pipe 1 to divert the stream line of the fuel and air in such manner that successive transverse sections, varying in fuel density will be brought together with more or less turbulence within the chambers defined by the blades and there caused to commingle so that in the resultant mass the fuel will be substantially uniformly distributed throughout the air, as illustrated ed in Fig. 8. For the purpose of describing the action of the distributor'it may be assumed that the carrier air. and fuel flow through pipe 1' at the rate of approximately per second. With the shaft rotating approximately 1500 M., or a single rotationof the" blades in one twenty-fifth of a second, and chamber- 3 approximately 24" of each horizontal section. of the flowing" steamof air and fuel contained within each unit of 2. The mass within each compart+ ment-is an average of the fuel distributed throughout the mass of a given unit. The above-rateof flow of the fuel stream, the number of revolutions of the bladesand their dimensions are given merely by way of-example. These factors may be varied .within widelimits according to conditions of the fuel and of the particular installation.

The operation may be further explained by assuming that thequadrants E, F, G and H, in'Fig. 7, represent portions of four dif: ferent; transverse sections stream, some parts of all of which are received in the compartment Aasthe blades are rotated througha complete cycle of 360. As compartment A sweeps over .the outlet of pipe 1, it will receive in its initial portions from quadrant E, a certain amount.

of fuel in a given volume of air; a relatively smaller amount of fuel in its second posi-Q be an average These alternate puffs or layer s of fuelandair flow through chamber 3,

and the relatively small quantities' of carrier air varying from rich to lean, as to fuel content, are discharged into chamber 5 in masses in whichthe fuel is distributed substantially uniformly,thus giving a resultant mass substantially homogeneous as to density; "It will benoted that the blades in their irotation act to displace successivetransverse sections of the stream laterally, and to sub.-

ject the moving stream to a 'succession'of latof the flowing receive successive sec-'- chamber 3 inin'sr'gsee I erally directed impacts, thus bringing about I more or less turbulence and a thorough inter mingling of the segregated masses distributed through the individual compartments A, B, C and D. Masses of different densities as to fuel content are brought into intimate relation and there is an interflow of the particles of coal from the denser portions to those less dense, by reason of the lateral displacement and sub-division of the'stream as it enters livered into chamber in a condition in which the fuel is distributed orspread evenly throughout the air in said chamber.

In Figs. 5 and 6 I have shown a means for dividing the column of fuel and air by means of a screw 20, which may also be used,

. As the screw is rotated at a relatively high speed it will slice off a portion of each succeeding horizontal section of the stream of air and fuel and in so doing will so subdivide the stream that as the mass is discharged at the upper end of the screw into the distributing chamber 5,'the several portions going to make up the resultant mass will have the fuel in a given unit of the mass uniformly and evenly distributed throughout the air.

Whatever means may be employed for dividing up the flowing stream of fuel and air, it must, in order to accomplishthe purpose of the present invention, be so proportioned relatively to the velocity of the fuel and air as to divide a given unit of the stream in such a way as to obtain,in the segregated masses, an average of the fuel in the several parts of the stream and to permit the several masses to so commingle as to secure an even or balanced distribution of the'fuel in the air as it is discharged into the distributing chamber 5.

What I claim is:

' 1. In combination with a main conduit for conveying .a stream of pulverized fuel and air, a rotatable member in said conduit, a casing forming a chamber into which the fuel laden air is delivered after passing said air, a casing forming a chamber into which the fuel laden air .is delivered, a plurality of delivery pipes leading from said casing, a rotatable shaft extending through said chamber and into said conduit, and a plurality of blades secured to said shaft in said conduit.

Signed at New. York city, in the county of New York and State of New York, this 13th day of May,"A. D. 1927.

" ERNEST H. PEABODY.

member, and a plurality of independent distributing pipes leading from said casing.

2. In combination with a main conduit for conveying pulverized fuel and air, a rotatable member in said conduit having blades extending longitudinally of the conduit, a casing forming a chamber into which the fuel laden air is delivered after passing said memher, and a plurality of independent distributing pipes leading from said casing.

3. In combination with a main conduit for conveying a stream of pulverized fuel and

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