US1706708A - Drier - Google Patents

Description

L. J. ROBB March 26, 1929.

DRIER 4 sheets-sheet 1 Filed July I3, 1925 NN Y L. J. ROBB March 26, 1929.

DRIER Filed July 3. 1926 4 Sheets-Sheet lil' INVENTOR Lun-'vv 2M March 26, 1929. 1 J., ROBB l 1,706,708

DRIER Filed July 5, 1926 4 sheets-sheet 5 INVENTOR -March 26, 1929.

L. J. ROBB DRIER Filed July 5, 1926 4 Sheets-Sheet INVENTOR e@ a@ @@1@ Q Patented Mar. 26',l 1929,.`

y A1,106,108 `f UNirEafsrATl-:s PATENT orifice.

LWIS l2-ROBE, OF IPITTBBURGH, PENNSYLVANIA, ASSIGNOB, T0 HEYL & PATTERSON,

me., or rxTTsBUaen, rENNsYLvANIA, A CORPORATION or raNNsYLvmm mum Appnauon med'zuiy a, 192e. serial No. 120,300.

Inthe preparation of coal for pulverizing the desired capacity for the apparatus I it isy important that the coal be dried'evenly preferablyemp oy a plurality of chutes and before 1t is supplied to the pulverizer. Vause a single take off means therefor. With rious schemes have been tried for this purthis arrangement the rate of .flow of ma.- pose, some of them* utilizing the gaseous erial through the entire apparatus may be roducts of combustion asa heating medium, regulated-by a single adjustment. v The dryut these attempts have not been Wholly lng -medium is preferably taken ofi' from successful. It is found in.v many cases that the 'drier proper and passed to a separator the material to be dried ignites incertainl Where any cntrained material is taken there- 'parts of the drier while in other parts .the from. 'moisture content is actually increased in'.` In the accompanying drawin s which i1- stead of being diminished. Evenv Where ig' lustrate the present preferred em odiment of nition does not take place the material dismy invention:

Figure 1 is a side elevation showin a 'char ed from these driers is likely to be varinle as to dryness and may be said to drier with the separator .for spent drying be streaked with moisture, and this of vHuid; course gives rise to serious difficulties in the Figure 2 1s a top plan view of the appara,v pulverizing operation. tus shown in Figure 1 but with the supply It has been proposed to i .use driers in bin removed;`A which the coal is moved in a vertical col- Figure 3 is an end elevation of the a umn between grids which act as ides for tus shown in Figure 1; the column of coal. In the use o these de- Figure 4 is a vertical longitudinal section vices it is found that the velocit lofthe to enlarged scale of a portion of the drier, drying gases has a tendency to hol the coal and einst the sides of the vertical grids and thus Figure 5 is a Vertical section through a ve rise to non-uniform operation. Also it -modified form of drier. A as frequently been found that the -trans- In the illustrated embodiment of the .infer of heat from the gases causes the coal to vention there is shown a drier indicated genheat rapidly on the incoming side and carry erally -by th'e reference character 2 compristhe moisture to the outgoing side, the result ing an outer shell 3 having a plurality of being an unequal drying of the coal and on inclined chutes 4 extending therethrough. occasion combustion thereof on the' incoming At the top of each chute 4 is a regulating side. gate 5 and a discharge leg of a supply `bin I provide a drier comprisin an inclined 6. The coal or other material flows from chute with take off means at t e bottom of the bin 6 through the gate 5 into the chute the chute for regulating the vflow* of material 4. At the bottom of each chute there is pro- With means for passing a drying `fluid' vided a short vertically extending portion through the material in the chute. Prefer- 7 Whose bottom terminates above but is ably there is provided a chamber through spaced away from a plate 8. (See Figure which the chute extends. This chute is pro- 4.) The downflowing material tends to pile vided with a grid on the under side through up on the plate 8, the material assuming its which the drying medium may pass land is natural angle of repose, until such llow is provided with a screen on the upper side checked by the bottom edge of the vertii'or defining the thickness of the column of cally extending chute portion 7. I have incoal to be dried. Preferably the chute is dicated by the letterI R on Figure 4 the ansupplied from a source of material adapted gle of repose for the material being handled to maintain the chute substantially full at and I make the plates 8 of such length that all times as this results in uniform drying. they extend beyond a line determined by the This supply means may constitute a bin with intersection of the line Rwith the plane of a regulating gate. the plates.

In order to secure regulation of the quan- Since the flow of the material from each tity of material being dried I referably chute is checked by the plate 8 the material employ a control for the take o means at piles up in the chute until it is substantially the bottom of the chute. In order to secure filled as shown in Figure 1.

ppara- .fluid to the material in the chute in such manner that binding of the material is eliminated.

The top of each chute comprises a screen 11 which is effective for defining the thickness of the column of material being dried.

The drying fluid, which may be waste gaseous products of combustion, is supplied to the apparatus through a conduit 12 having outlets 13 leading to the drier 2. One of these outlets is provided for each chute in the drier r2 and a division plate 14 is provided within the drier for completely isolating one chute and its gas supply system from the other.

The hot gases pass from the space within the drier below the bottom plate v 9 through the slots 10. The gases pass through the column of coal, drying the same, and then pass olf through the screen 11 to the space 11 inthe drier above sugh screen. Outlets 15 are provided on the side. of the drier remote from the inlets 13 and these communicate through a manifold 16 with a conduit 17 leading to an exhauster 18. The exhauster discharges into a conduit 19 leading to a cyclone collector 20. This collector is effective 'for separating entraine/d particles of dried material from the exhaust gases. The collected material is discharged into a screw conveyor 21 by which it may be taken to the pulverizer or any other desired place. i

Referring now in more detail to the drier 2,v the chutes 4, as already pointed out, are inclined. These chutes may be made at any angle from 35 to 50 from the horizontal but it is found that the nearer the angle approaches 45 the more easily and uniformly will the coal flow through the apparatus.

The screens 11, while effective for defining the thickness of the column of coal flowing through the apparatus, must of course be open enough to permit of free discharge of the drying gases and due to thisfact and also due to the tendency of the drying gases to entrain small particles of solid material, a certain amount of material may get into the space above the screens 11 but still not be carried through the outlets 15 to the conduit 17. I therefore provide a baille plate 22 which makes it necessary for the gases to move downwardly and then upwardly, as indicated by arrows in Figure 4, in order to get out of the drier. The solid particles tendency seems due, at least in part, to the fact that atmospheric gases are drawn upwardly through the coal lying in the discharge legs 7. To offset 'this tendency, I prefer to employ one or more flexible bailles 22b secured to the legs 7 as shown. These baffles, While they permit free action of the discharge mechanism, increase the resistance to the upward flow o-f atmospheric gases. They will have this effect even though they are held clear of the plate 8 by dried coal,

as in this case they increase the length of the gas path by substantially their own length.

When dealing with material of this character it is of course possible for such material to percolate into all parts of the apparatus. The tendency of the material to sift through the grids 9 is minimized by the provision ofthe horizontal slots 10, but hand holes 23 having suitable cover plates are provided forcleaning out the wind boxes below the chutes.

With the apparatus so far described there is no tendency for the columns of coal to move through the apparatus because of the fact that the coal itself chokes off the flow. The means for controlling the flow of solid material through the apparatus will now be described.

A pair of shafts 24 and 25 is provided at each end of the discharge chamber 26 in which the plates 8 are located and sprockets 27 yare placed on each shaft. A pair of sprocket chains 28 extends around the sprockets 27, passing over the plates 8 near each side thereof. The sprocket chains 28 are connected at intervals by cross bars 29 which pass between the plates 8 and the bottom of the chute portions 7 as shown in Figure 4. These bars act as Scrapers or sweeps and are effective for sliding the dried material over the plate 8 from which it falls into a bin 30. When the material is swept out from under the chute the material in the chute moves downwardly until its flow is again checked as above described.

The speed of the discharge mechanism and therefore the rate at which material is dried in the apparatus is controlled entirely by the speed of the shaft 24. This shaft is connected through a sprocket chain 31 toa drive sprocket 32. The drive sprocket 32 -is connected to a driving motor 33 through a speed reducer 34 and a speed controller 35 is provided for the motor 33. By' suitably regulating the speed controller theflow of material through the apparatus may be regulated as desired. The flow of heating gases through the drier may be regulated by a controller 18 connected to the motor 18m which drives the exhauster 1,8.

In Figu form of apparatus wherein each of the inclined coal chutes is formed from a plurality of staggered portions. This arrangement may be used to secure greater drying capacity. Inthis form of the invention parts corresponding to similar parts in the first described embodiment have been given the same reference character with a letter suffixed. It will be noted that each section of the chute has its own fluid supply means, and these are referably indepen ently regulable. It will also be noted that 1n the lower section the ses travel through -the coal from left to` right, while in the section thereabove they travel through the coal from right to left.

I have illustrated and described a preferred embodiment of my invention as particularly applied to the drying of coal. It will be understood, however, that the inven tion is not limited to the form shown as it may be otherwise embodied within the scope of the following claims.

I claim:

1.. A drier, comprising a chamber having an inclined chute therein, means for supplying drying gases to the chamber below the chute, the chute having a perforate bottom plate to. permit passage of the drying ases therethrough, and a perforate top plate for the chute, the chamber being provided with a discharge outlet for material above the top late.

2. A rier, comprising a chamber having an inclined supporting surface therein for material to be dried, means spaced from the supporting surface for determining the thickness of material thereon, means for passing a drying Huid through the material,

and a discharge outlet for the material collecting above the -means which determines the thickness of the material.

3. A drier, comprising an inclined chute,

.I take. olf means at the bottom of the chute,

means for passing a gaseous drying fluid from side to side through the material in the chute, and a baille for atmospheric gasesl at one end of the chute.

` 4. A drier, comprising an inclined chute,

vtake ofi' means at the bottom of the chute,

means for passing a gaseous drying fluid from side to side through the material in the chute, a plate spaced from the bottom of the chute, a sweep adapted for movement between the plate and the bottom of the chute, and a yieldable baille in the path of the sweep.

re 5 I have shown a modifiedl 5. A drier, comprising a chamber having an inclined perforated supporting surface therein formaterial to be dried, perforated means spaced from the supporting surface for determining the thickness of material thereon, means for passing drying, fluid means spaced from the supporting surface for determining the thickness of material thereon, means for passing drying fluid through the material, supporting surface and. spaced. means, means for causing the drying fluid after passing through 'the spaced means, to move along the upper surface thereof for removing particles of material deposited thereon and a discharge outlet for the material collected above the spaced means.

7. A drier, comprising a chamber having an inclined perforated supporting surface therein for material to be dried, perforated means spaced from the supporting surface for determining the thickness of material thereon, means for assing drying fluid through the materia, supporting surface and spaced means, means for causing the dryin fluid, after passing through the space means, to move along the upper surface thereof for removing particles of material deposited thereon and a discharge outlet for returning the material collected above the spaced means to the main body of the material.

8. A drier, comprising a chamber having an inclined perforated supporting surface therein for material to be dried, perforated means spaced from the supporting surface' for determining the thickness of material thereon, means for passing drying fluid through' the material, supporting surface and spaced means, means for causing the dryin fluid, after passing through the space means, to move along the upper surface thereof for removing particles of material deposited thereon and a discharge outlet for returning the material collected above the spaced means to the main bod of the material below the supporting sur ace.

9. In a drier, a chamber, a perforated chute disposed within the chamber, means for passing drying fluid through the chamber and material therein, and a baille for directing the drying fluid along the lee side of the chute for removing particles of material adhering thereto.

10. In a drier, a chamber, a perforated chute disposed within the chamber, means for passing drying fluid through'the chamber and material therein, and a'baille for directing the drying fluid along the lee side of the chute for removing particles of material adhering thereto and for im artingv a sudden change in the movement o the fiuid for discharging the particles of material.

11. In a drier, a chamber, a perforated chute disposed Within the chamber, means for passing drying fluid through the chamber and material therein, a battle for direct- In testimony whereof I have hereunto set 20 my hand.

LEWIS J. ROBB.

CERTIFICATE 0F CDRRECTIN.

Patent No. 1,796, 708.

Granted March 26, 1929, to

LEWIS J. ROBB.

lt is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as toliows:

Page l, at the beginning of the specification, insert the iirst paragraph "This 'invention relates to driers and is particularly useful for the drying of coal or other material in granular form."; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 23rd day of April, A. D. 1929.

(Seal) M. J. Moore, Acting Commissioner of Patents.

CERTIFICATE 0F CGRRLCTTQN.

Patent No. 1,706,708. Granted March 26, 1929, to

LEWIS J, ROBB.

lt is hereby certified that errer appears in the nrintetl specification of the above numbered patent requiring correction as ioiiews: Page l, at the beginning of the specification, insert as tire first paragraph "This invention relates to driers and is particularly useful for the drying oi ceal or other material in granular form."; and that the said Letters Patent sirouid he read with this correction therein that tire same may conform to the record ei tire case in the Patent Office.

Signed and sealed this 23rd day of April, A. D. 192,9.

M. l. Moore,

(Seal) Acting Commissioner of Patents.

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