US1334023A - Centrifugal drier - Google Patents

Description

G. H. ELMORE.

CENTRIFUGAL DRIER.

APPLICATION FILED ocT. 7, 191e.

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' wsasgg gvwemtoz G. H. ELMORE. CENTRIFUGAL DHIER. v APPLlcATIoN FILED ocT.1l |916.

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Patented Mar. 16, 1920. Il l G. H`. ELMOHE.

CENTRIFUGAL DRIER.

APPLICATION FILED OCT. 7, 1916.

1,334,023, Y Patented Mar.16,1920.

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G. H. ELMORE. CENTRIFUGAL DRIER. APPLICATION FILED ocT.1. I9I6.'

Patented Mar. 16,1920.

UNITED sTATEs PATENT oEEioE.

GUY H. ELMORE, 0F SWARTHMORE, PENNSYLVANIA.

CENTRIFUGAL DRIER.

Specification of Letters Patent.

Application filed October 7, 1916. Serial No. 124,348.

tend to cake on and clog the screen element of the drier.

The invention involves features described and claimed in my Patent No. 1,235,193, July 31, 1911 which resulted from ay copending application, Serial No. 718,931,.filed September 6, 1912, and these accordingly are not. claimed herein.

Generally stated the present invention involves a downwardly flaring conical screen mounted to rotate upon a. vertical aXis,the

flare or angle of the conical screen being so chosen that with the material handled and at the speed chosen for operation the centrifugal feeding tendency will not be quite` sufficient 'to effect a feeding of the material down the screen. In conjunction with this rotating screen I use a coaxial rotating conveyer having substantially helical nights of relatively quick pitch` the conveyer rotating at a slightly different, and preferably at a slightly slower speed than the screen. The difference in speed and the pitch of the flights are chosen so as to feed the material down the conical screen at such speed that it will be dewatered to the desired degree by the time it is discharged from the lower end of the conical screen. By proper design a condition may be realized at which the conveyer need exert only a slight feeding tendency on the granular material to secure the desired action and consequentlyvthe conveyer blades may be given a very quick pitch and the difference of speed of the conveyer and screen may be accordingly rela.- tively slight so that the wear is reduced to a. minimum. v

The above features are characteristic of Iche structure described and claimed in my Patented M'ar. 16, 1920.

prior application above identified. It has I been found, however, that in handling certain materials usually those of a fine granular texture, such as crystalline saltsJ there is a tendency for the screen ultimately to clog. requiring stopping of the machine and cleaning of the screen. There is necessarily a clearance allowed between the conveycr blades and the'screen and this leads to the formation of a film or layer of granulaimaterial which remains on the screen and does not move forward with the bulk of the material handled by the drier. The formation of this *layer is beneficial-because itl `serves as a. so-rt'of filter bed, preventing the finer particles 4from passing through the meshes of the screen as they would otherwise do. In time, however, this layer `becomes substantially impervious to water, hindering the action of the drier, and it is desirable periodically to remove this film or layer and thereafter allowl a new one to form. The purpose of my invention is to accomplish this effect automatically and without requiring the stopping of the drier and without interrupting its continuous action.

The means utilized for this purpose is a mechanism which reduces the clearance pe-r riodically and temporarily between the conveyer blades and the screen. As the simplest mode of effecting this result I have adopted a relative axial movement of the screen and conveyer elements which is automatically effected at set periods during the operation of the machine. Either the screen element or the conveyer element or both might be shifted but as the simplest and most satisfacto1y-method I prefer that of shifting the conveyer element and a machine embodying this particular arrangement is illustrated in the accompanying drawings1 in which Figure 1 is a vertical axial section of such a machine;

Fig. 2 is a section on the line 2-2 of Fig. 1;

Fig. 3 is a fragmentary view showing' the screen structure in section with a part of the interior screening element broken away the conveyer element being shown partly in section and partly in elevation, a portion of the same being also broken away to give a clearer view of the screen;

Fig. 4 is a section on the line 4-4 of Fig. 1;

Fig. 5 is a fragmentary elevation looking at the right hand side of the machine with reference to Fig. l;

Fig. 6 is a section Von the line 6 6 of Fig. 1; and

Fig. 7 is an enlarged view showing the .bearing and bearing adjusting mechanism for the quill shaft which carries Ithe conveyer element.

The entire machine is supported in a combined frame and hopper structure which comprises a base plate 11, an interior shell 12 and an exterior shell 13, the annular space between the shells 12 and 13 being the discharge hopper for the dried material leaving the machine. The annular space between these two shells is not continuous except at the top adjacent the point of d-ischarge from the screen as it is necessary to form openings through -the shells at opposite sides of the machine to permit access to the drive mechanism. Consequently steep inclined webs or partitions 14 extending between the shells 12 and 13 are provided to direct the dried granular material to the two discharge openings 15I which lead through the base plate 11. The frame thus forms two funnel like portions which Awill direct the dry granular material to the discharge openings and prevent banking or accumulation of the dried material.

The upper end of the shell 12 curves inwardly at 16 to form a guard flange intended to prevent any material from entering the machinery space inside the shell 12. The flange 16 extends upward Within the conveyer rotor shell far enough to secure this result. The shell 13 carries at its upper end an exterior trough or launder 17 having water discharge openings 18 designed to convey away water and other liquids which may be extracted by the drier. The outer wall of the launder 17 is provided with internal lugs 19 to support a removable conical guard shell 2Q, which incases the screen and dellects the water passing through the screen downward into the launder 17.

Mounted directly on the base plate 11 is a bearing plate 21 which carries a ball thrust bearing 22 and a ball journal bearing 23 for a. vertical shaft 24 which is driven through the belt pulley 25. This is the main drive shaft of the machine and carries the screen. Extending across the frame structure of the machine and removably bolted to the shell 12 near the top thereof is a cross frame 26 in which is threaded an adjusting nut or slideway 27 Mounted to slide vertically in this slideway is a sleeve bearing 28 which carries a ball thrust bearing 29. Turning in the sleeve bearing 28 is the quill shaft 30 Within which turns the shaft 24. The quill shaft 30-earries at its upper end 31 and the connected quill shaft 30, through -the interposed ball thrust bearing 29. The

lowermost posit-ion assumed by the sleeve bearing 28, and consequently by the quill shaft and the conveyer element, may be adjusted byadjusting the nut or slideway 27. Thus the sleeve bearing 28 not only guides the shaft 24 and the quill shaft 30v in their rotary movements, but also guides the quill shaft in its vertical or axial movements relative to shaft 24, and is the medium through which the lifting' or shifting force is applied. This shaft 24 carries at its upper end the spider or frame for the screen element. This spider comprises a hub portion 35 held against a shoulder on the shaft 24 by means of a suitable nut and washer 36; a series of radial spokes 37 which are so formed as to com-prise helical .conveyer blades; an upwardly extending annular rim 38 forming a receiving` hopper and a downwardly flaring conical grating structure consisting of th elemental bars 39 and annular flanges 40 which connect the same. The lower edge of the screen spider takes the form of a grooved water guard ring 4l which straddles the upper edge of the shell 13 and keeps separate the dried granular material and the water separated therefrom as the two are discharged respectively from within and without the screen.

The-screen proper consists of perforated plates or other suitable foraminous material 42 applied in sections to the interior of the spider and retained the-rein by tapered locking bars 43 which are drawn by bolts 44, into grooves formed on the interior of the spider. These grooves are preferably formed in enlarged bars 45 similar to the bars 39-which occur at regular intervals. The edges of the foraminous material are bent into the aforesaid grooves at either side of the bars 43, and are clamped therein by setting up the nuts 44 as will be apparent upon an inspection of Figs. 2 and 3. The bell shaped shell 31 of the conveyer element is mounted within the screen structure just described and has a flare or taper conforming to that of the screen. The shell extends downward.

to the upper extremities of the flanges 16 described as formed on the upperend of the shell 12 and is provided on its outer face with a plurality of qui-ck pitch helical conveyer flights which turn in close proximity to the interior surface of the screen', only the bracket 48. A grease cup 53 communieating with ducts 54 in the journal pin is provided to lubricate the sleeve 51. A pair of gears 55,56 of slightly different sizes are fast on the sleeve 51, the'gear 55 meshing with a companion gear 57 fast on the quill shaft 30, and the gear 56 meshing with. a

-companion gear 58 fast on the main shaft 24. The ratio of the gears is such that the quill shaft 8O is driven through the gear train by the shaft 24 at a slightly lower angular velocity. The bearing between the shaft 24 and quill shaft 30 is lubricated by means of a grease cup 59 which is covered -by a removable cap 60 and communicates with suitable ducts 61 in the shaft 24. Oil

Vwill be continually supplied to the thrust bearing 29 and the sleeve bearing 28 by means of a pipe 62, which dips into an annular trough 63, formed in the" upper face of the gear 57, pressure to lift the oil being supplied by the centrifugal tendency of the oil in the trough 63. A groove 64 is formed at the lower end of the sleeve bearing 28 to catch any excess oil that may How down the bearing and feed it by means of a pipe 65 (see Fig. 7) to the trough 63.

The structure so far described is available for use as a drier Where the self-clearing action is not essential.

The mechanism for lifting the sleeve 28 and consequently the conveyer element to' reduce the clearance'hbetween the latter and the blades of the screen in order to cause the clearing of the screen Will now be described.

Fast on the shaft 24 is a Worm 66 which meshes with a Worm wheel 67. The Worm wheel 67 is fast on a shaft 68 which turns in bearings 69 on the cross frame 46. .The frame 4 6 is lformed with anoil retaining recess 70, in which the worm and Wheel run so that these are thoroughly lubricated. Thesh'aft '68 is also supported by a bearing 71 Carried onthe shell l2 and carries at'its outer end a. radially slotted Crank 72. A crank pin 73 is provided and this may be clamped in any desired radial adjustment inthe slot of the crank 7 2 so as to adjust the throw'thereof. The crank pin 73l is connected by a short connecting rod 74 (which is made adjustable in f length by means of aturnbuckle) to the vertical arm -as the machine is driven the disk 78 will be intermittently rotated in one direction. The disk 78 is fast on a shaft 79 mounted in suitable fixed bearings 80 and carrying a worm 81, which in turn drives a worm wheel 82 fast on shaft 83. This shaft turns in the fixed bearings 84. The shaft 88 carries a cam 85 having a radial projection or finger 86. The cam 85 bears against a.roller 87 on the. vertical depending bifurcated arm 88 of a bell crank whose two horizontal arms 89 extend beneath and bear against 'the sleeve bearing 28. Thus as the machine is driven the cam 85 is slowly and intermittently rotated and when the finger 86 engages the roller 87 it will force the same to the left as viewed in Fig. 1, thus lifting the sleeve bearing 28 and with it the quill shaft 30 and conveyer shell 81 so that the conveyer flights will move virtually into contact with the inner face of the screen and clear the same of the accumulated layer of granular material forcing such material to discharge from the machine. Thereafter the passage of the .finger-86 past the roller 87 will allow the conveyer rotor to sink back to its original position restoring the original clearance between the conveyer blades` and the screen. The amount of this normal clearance is adjusted by adjusting the nut 27. In order to permit a corresponding adjustment of the bell crank 88, 89, this is journaled on a shaft 90, whose ends are mounted in slide blocks 91. These are 'mounted in vertical guide-ways 92 and may be adjusted vertically therein by means of adjusting screws 93. A considerable range of adjustment of the frequency of the clearing action may' be had by adjusting the throw ofcrank pin 73, an adjustment of the length of the connectingl rod 74 being made if necessary to preserve the proper position of the ratchet bell crank structure 75, 7 6.

The operation of the device will be readily understood from the above description. Briefly the characteristic operation of the machine is:

The granular material fed to the rotating hopper at the top of the machine will be urged downward by the conveyer blades 37, and will be quickly thrown by centrifugal force against' the screeir The centrifugal tendency of the material is nOt `Sufficient to feed it down the Screenbut this feeding is brought aboutI by the inclined conveyer blades carried by the conveyerrotor which is'turning at slightly less speed. The moisture contained in the material. will be thrown through the screenZandldeflected by the cover 20 into the launder 1 7 f1fQm Whicl rit will flow to Waste. "The dried granular' ina; terial upon leaving the screen will yflow downward between'the shells 12 and 13 and will be discharged to any suitable container through the 'openings l5. During the major portion of theoperation of the device there will be sufiicient clearance between the conveyer blades of the screen to'permit the existence of a layer or bed of granular material to serve as a sort of filter, but this bed will be periodically removed by the rising of the conveyer element. In this way clogging and blinding of the screen are prevented and continuous operation is secured.

The construction above described has certain, practical advantages of accessibility and easy adjustment. The exterior portion of the screen is exposed by merely removingl thecover 20. The removal of the oil cap and a single nut permits the removal of the entire screen structure for replacement or repair, and this exposes the entire exterior portion of the conveyer rotor. The conveyer rotor may be lifted out, together with the quill shaft, by the mere releasing of the gear 57 which is held by a single nut, as clearly indicated in Figs. l and 3.

The shifting mechanism is all accessible for adjustment or repair without disman- 'tling the machine as the bearings for this mechanism are readily dismounted. The shifting mechanism is mounted in what would otherwisebe waste space in the drier, so that the size of the machine is not increased by the addition of this mechanism. In driers for handling material which has no tendency to'c'ake upon the screen the entire shifting mechanism may be omitted; no other chang-e being required.

Having thus described my invention, what I claim is l. Ina centrifugal drier, the combina-` tion of a rotatable annular screen; a conveyer element mounted to rotate coaxia-lly with said screen within the same and having scrapers or flights moving near to but out of contact with said screen; and an automatic mechanism operating periodically to reduce the clearance between said screen and flights to effect a clearing of the screen.

2. In 'a centrifugal drier, the combination of a rotatable screen; a conveyer element provided with helical flights mounted to rotate coaxially with said screen to feed material along` the same; and autou'latic mechanism for moving said 4conveyer to reduce temporarily 'the clearance between it and the screen to cause clearing of the screen.

3. The combination of a flaring rotary screen; a conveyer element mounted to rotate coaxially within said screen to convey material along the same; and means for periodically producing a relative axial movel ment of said screen and conveyer to reduce the clearance between the same.

4. The combination of a conlcal rotary shafts in the same speeds and'periodically shifting said quill shaft axially to temporarilyl reduce the 5. The combination of a substantially conical rotary screen; a conveyer element.v

mounted to rotate coaxially therewith and provided with substantially helical fiights; means for driving said screen and conveyer element in the same direction at slightly different speeds; and a mechanism for producing a relative axial shifting movement between the screen and conveyer to periodically and temporarily reducethe clearance between the same. V 6.The combination of a substantially conical rotary'screen; a conveyer element of the spiral type mounted to rotate coaxially within the same; and a driving mechanism adapted to rotate said screen and conveyer' in the said direction at different speeds and periodically to produce a relative shifting motion between the conveyer and screen to change the clearance between the same. l

7 In a rotary drier the combination of a flaringl annular rotary screen; a. rotary conveyer mounted coaxially within the saine and spaced from the screen to permit the formation of a layer ofthe material being dried; and means for periodically causing said conveyer to remove and discharge said layer during the normal operation of the machine.

8. In a centrifugal drier, the combination of a rotary shaft; a substantially conical screen carried thereby; a quill shaft journaled on said shaft; a conveyer element having spiral ights carried by said quill shaft; and an -actuating mechanism for rotating said shafts in the same direction at unequal speeds and periodically shifting said quill shaft axially to temporarily reduce the clearance betweensaid conveyer element and screen.

9. In a centrifugal drier, the combination of a rotary shaft; a substantially conical screen carried thereby; a quill shaft journaled on said shaft; aconveyer element having spiral flights carried by said quill shaft; an actuating mechanism for rotating said direction at unequal clearance'betweensaid lconveyer element and "scre'en; and means to vary the frequency of the periodic shifting action.

-10.`In 'a centrifugal drier, the combination of a rotary shaft; a substantially conical screen carried thereby; a quill shaft journaled on said shaftga conveyer element having spiral flights carried by said quill shaft; a gear train interposed between said shafts to constrain them to rotation in the same direction at unequal speeds; and a shifter'mechanism driven from one of said shafts and operatively related to both shafts to periodically cause a relative axial shifting movement of said shafts to reduce temporarily the clearance between the conveyer and szreen.

11. In a centrifugal drier, the combination of a rotary shaft; a substantially conical screen carried thereby;" a quill shaft journaled on said shaft; a conveyer element having spiral flights carried by said quill shaft; a gear tram interposed between said shafts to constrain them to rotation in the same direction at unequal speeds; a shifter mechanism driven from one of said shafts and operatively related to both shafts to periodically cause a relative axial shifting movement of said shafts-to reduce temporarily the clearance between the conveyer and screen; and a change speed mechanism interposed in the drive to said shifter mechanism to vary the frequency of its ac-4v tion.

12. In a centrifugal drier the combination of a flaring rotary screen; a conveyer element mounted to rotate coaxially within said screen to convey material along the same; a frame for supporting said screen and conveyer element; two thrust bearings mounted in said frame, one of said bearin s supporting said screen and the other of sald bearings supporting said conveyer element; and means for adjusting one of said thrust bearings in said frame to adjust the clearance between said screen and conveyer element. Y v

13. In a centrifugal drier, the combination of a flaring rotary screen; a conveyer element mounted to rotate coaxially within said screen to convey material along the same; step bearingsindependently supporting said screen and conveyer element; a support in which one of said bearings is slidably mounted; -and adjustable means for limiting the sliding movement of said bearing in said support whereby the maximum clearance between said screen and conveyer element may be limited. n

14. In a centrifugal drier, the combination of a flaring rotary screen; a conveyer element mounted to rotate coaxially within said screen to convey lmaterial along the same; adjustable" means for limiting the axial separating movement of said screen and conveyer; and an automatic shifter mechanism operating periodically tol reduce the clearance between said conveyer and Vscreen by a relative axial shifting movement of the two.

15. In a centrifugal drier, the combination of a substant1a1ly cylindrical frame structure forming an annular discharge chute for the dried material; a conical screen rotatably mounted on said frame structure above the same and adapted to discharge.

'into said discharge chute; a rotary conveyer element mounted coaxially within said screen; a driving mechanism for driving said screen and conveyer in the same direction at unequal speeds; and a shifting mechanism adapted to eHect a periodic axial shifting movement of the screen and conveyer to vary the clearance between the same, said driving and shiftin mechanisms being mounted wholly within the cylindrical portion of said frame structure.

In testimony whereof I have signed my name to this speclcation.

' GUY' H. ELMoRE.

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