US1821684A - Rotary pulp screen - Google Patents

Description

Sept. 1, 1931. J.'A. WIENER 1,821,684

ROTARY PULP S GREEN Filed Jan. 6. 1931 2 Sheets-Sheet l INVENTOR ATTORNEY p 1931- J. A. WIEN'ER 1,821,684

ROTARY PULP S GREEN Filed Jan. 6, 1931- 2 Sheets-Sheet 2 Z l 4 INVENTOR.

ATTORNEY Patented Sept. 1, 1931 UNITED STATES JOHN A. wIENnmoF oswneo, NEW YORK ROTARY PULP SCREEN Application filed January 6, 1931. Serial No. 506,909.

normally open top and an imperforate con-' cavo-convex bottom, the unscreened pul or stock comprising, for example, groun wood suspended in water beingdelivered to the top of the screen and conducted thence toward the contracted bottom by means of a concentric spout, the latter having a flared bottom by which the stock is spread or deflected horizontally towards the inclined walls of the cone, andthereafter wells upwardly to a predetermined level, which is usually maintained throughout the screening operations. A particuar object is to provide a basket-like frame having a flared annular open top portion, the latter being connected with the bottom portion by a series of ribs spaced to provide openings that are closed by the screen plates, the said plates being detachably secured to said ribs and-forming a continuous relatively smooth inner surface which obviates the usual tendency of the pulp to felt said surface and clog the relatively fine slots or openings of said plates. The basket is mounted rigidly'upon a vertical shaft by which it may be rotated at any suitable speed. In practice, the speed at which the basket is rotated is such as to create a certain degree of centrifugal action by which the liquid mass is forced radially against the plates to effect the screening. This centrifugal action also tends to force the unscreened stock delivered by the feeding-spout upwardly over the'inner surface of the cone, thereby to separate all coarse particles, such as splinters, knots, grit, and the like, which are unfit for papermaking, from the acceptable stock that passes through the screen plates and is collected by the vat, from which said stock may fre'elyflow into a box or other receptacle ready to be delivered to the papermaking machine. The top of the hopper-like screening member is shaped like the mouth of a bell to provide an easy means of escape for the coarse refuse, which according to the present mechanism, gravitates into an annular trough that surrounds the mouth of the hopper, to be carried away by suitable means. The closed bottom of the screening member is kept free and clear of the coarse waste material by the continuousv flooding and washing effected by the strong downward pressure exerted by the relativelylong column of unscreened stock that flows through the feed-spout. This freeing and cleansing, as well-as the centrifugal action is facilitated by the peculiar shape of the inner surface of said bottom port-ion and the inclination of the screen plates. These .several actions tend to keep the stock to be screened moving continuously upwardly and effects the complete separation and disposal of the refuse without loss of any of the acceptable or serviceable pulp, and besides prevents the coarse material from collecting either at the bottom or at the sides of the hopper, as explained. And a further object is to provide novel and simple mechanism for producing short and quick vibrationsof the shaft and hopper, which agitate the pulp and tend to prevent clogging of the slotted portions of the screens.

I attain these objects by the means set forth in the detaileddescription which follows,and as illustrated by the accompanying drawings, in whichg Figure 1 is a top plan view of the complete machine. Fig. 2 is a horizontal section, taken, on line 2-2 of Fig. 4. Fig. 3 is a plan view of one of the slotted screen plates. Fig. 4 is a transverse vertical section, taken on line 44 of Fig. 1, showing the detail construction of the inverted cone-shaped screen, the driving, and alsothe vibrating mechanism. Fig. 5 1s an enlarged transverse section of the hopper and an elevation of the feed-pipe, the section being taken on line 4 -4 of Fig. 1, showin a modification of the screen plates. And Flg. 6 is an enlarged transverse vertical section, taken on line 6-6 of Fig. 4, showing the eccentric mechanism that effects the vibration of the shaft and screen.

In the drawings, 2 represents the pulp-col- I 1 lectin vat, which may be supporting by legs 2', an having a normally open top 2a and a closed bottom 2b, the latter being perforated erably ivided vertically and longitudinally by a sectional partition do, by means of which different levels of the pulp in the vat and screen may be regulated, as indicated by dot- 1 shaft 3 is enlarged to orm a plunger, as 3',

ted line in Fig. 4.

The screen, preferably an inverted frustum cone 5,'compr1sesa basket-like frame having an annular flared top or mouth 5 and an imperforate concavo-convex bottom 5a, the latter being bored axially to receive the shaft 3 with which the basket is rigid and-therefore rotatable. The top 5. and the bottom 5a are preferablyconnected and spaced b ribs 5b, to provide tapered openings 50, whic are closed y corresponding y shaped slotted or woven screen plates 6, t e latter preferabl overlapping the ribs, and their lateral e ges abutting, as shown in Figs. 1, 2, 4 and 5. The piates 6 are usually secured to the ribs 5b by screws, as 6', and in the preferred arrangement, the plates are formed with several series of relatively fine vertical screening slots, 'as 6a. By this constructionxand arrange-' ment, the whole inner surface ofthehopper 5 is substantially sinooth and free from humps or crevices that might cause felting or clogging when the hopper is filledwith unscreened stock. .The unscreened stock, which for paper-making comprises ground wood suspended in water, is delivered to the bottom of the ho per 5 by means of a concentric ipe or spout which loosely telesco the aft 3 and is supported b spa s iders .7 through which the sha passes. e topof spout 7 referably extends slightly? above the piano 0 the bell top of the hopper, and its ttom is preferably flared outwardly, as at 70, in order to spread and deflect the gravi tating stock in all direetions horizontally over the concave inner surface of the bottom 5a. The flare of the spout 7 is preferabl arranged substantially araliel-to a'conica cen tral portion, as 51!, o the bottom, to accelerate the free flow of the stock. This insuresthe constant washin of said bottom portion "bearings 10', that rise from a block-12. The

ley, as 10a10c, shown in Fig. 4. The block 12 is formed with a U-shaped cavity 12' comprising a reservoir which is partially filled with oil or other suitable fluid, as 12a, whose displacement by an eccentric pump 13, effects the axial vibration of the shaft 3 and screen 5. For this pur ose, the lower end of which is reciprocable in the larger caliber arm, as 120 of the reservoir, while in the smaller caliber arm 12d, of the reservoir, is reciprocably disposed a plunger 13. The concentric mechanism that operates the plunger 13' is mounted upon and actuated by shaft 10, as shown in Figs. {and 6. By this arrange. ment, the downward movement of plunger 12d displaces the oil 12a and lifts the shaft and hopper, while the downward movement of said parts is effected by gravity alone, following each upward movement of the plunger 12d. The strokes of the pump 13 are prefer ably relatively sli ht and when shaft 10 is rotated at a s ie of one hundred or more R. P. M., the vi ratory movements of the hopper 5 are relatively short and quick and tend to so agitate the body of the pulp within the hopper 5, as to prevent the solid particles suspended in the liquid from clinging to the inner wall of the be per.

rounds the mouths of the vat and hopper, and

from which the refuse may be carried away, as by a pipe 14. In the present device, the wei ht of the shaft 3 and the hopper 5 is virtua y supported by the fluid 12a.

It will be understood from the present The agitation educed by the axial vi rations of the screen.

novel construction of the hopper 5, having screened stock, that the latter, owing to the of thespout 7 and the concave of the inner surface of the bottom, creates more or less ebullition in the vicinity of the bottom ends of the screen piates and this boiling action tends to start the upward motion of the buoyant splinters, knots, and the like, which are thereafter kept moving in the said direction by the centrifugal force and the vibrations of-the hopper, so that by the time the coarse particles reach the tops of the slots 6au, complete se'paration of the acceptable pulp from the said refuse is efi'ected, and

Ill

' when the waste is finally ejected from the screen, there can be no loss of acceptible pulp,

and hence the usual rescreenin ings is entirely obviated. By t e herein described method and means of screening, there is little danger of the screen becoming clogged and requiring frequent shuttingdown of the machine for cleaning the plates 6', and there being praciic'ally no loss of serviceable pulp, nor interruptions of the operation of the machine, the present improvement insures higher efficiency than any other may be fastened to the common ribs' 511- by screws 6', as shown. In other respects, the hopper may be cons ructed the same as shown in Figs. 1, 2 and 4. This arrangement of sectional screen plates has 'for its object to interrupt and change the flow of the screenable pulp towards and through the slots of the plates for the purpose of agitating the same to lessen the danger of felting and cloggin" of the screen plates.

I-faving thus described my invention, I claim, is- V 1. A rotary pulp screen, having in combination with an open top vat and an upright shaft journaled in the bottom of the vat, an inverted hollow frustum cone rotated by the shaft comprising a flared open top portion and an imperforateconcave bottom portion separated by screen plates, a gravity feedspout loosely telescoping the shaft and havinga flared bottom end adapted to deflect the unscreened stock radially to wash the what concave surface of the bottom and supplement the centrifugal force caused by the'rotationof the cone to effect the upward 'movement of the coarse refuse whereby to separate said refuse from the acceptable stock that passes through said plates and to spill said refu-e over the top of the cone, and means to drive said shaft.

2. A rotary ulp screen including a vat and an upright shaft extending above and below the bottom of the vat, a hollow conical basket supported and rotated by the shaft, comprising an annular top portion and a concave bottom portion connected and spaced by inclined screen plates, a spout to conduct the unscreened stock towards the bottom of the basket, the bottom end of the spout being flared to correspond to the concave of the bottom of the basket to effect continuous washing of the bottom and to so agitate the stock after it leaves the spout as to prevent accumulation in the lower. portion of the tail-- of the basket of any of the refuse or sediment, the discharge from the spout being of such nature as to start a strong upward flow of the stock over the screen plates whereby to enable the centrifugal force created by the revolving basket-"to carry the refuse upwardly above the screening zone and to cause said refuse to spill over the top of the 'basket.

3. A pulp screen having in combination with an open top vat, a hollow upright body ing concentrically through the vat and body to rotate the latter, said body having an open top and an imperforate concave bottom connected and spaced by inclined screen plates, a gravity feed-spout for the unscreened stock disposed concentrically in the body and supported by the'shaft, the bottom of the spout being expanded and adapted to deflect the unscreened stock radially to wash the concave surface of the bottom and to start the'flow of the unscreened stock upwardly over said plates, meansto drive said shaft to create centrifugal force to continue the upward movement of the stock to effect the separation of the coarse refuse from the acceptable pulp that passes through the screen plates and to cause said refuse finally to spill over the top of the body, and means to vibrate the hopper to prevent felting and clogging of the screen plates.

4. An upright rotary pulp screen, having in combination with an open top vat,,an inverted cone-shaped screen disposed in the vat, having a circular arrangement of inclined screen plates, a shaft passing through the bottom of the vat and centrally through the screen, a gravity feed-spout loosely telescoping said shaft adapted to carry the unscreened stock towards the bottom of the screen, the top of said screen being open, the bottom of the screen being'imperforate and concave, the bottom end of said spout being flared and arranged parallel to the concave of the bottom adapted to deflect the stock radially with sufficient force to keep said bottom clear and free of splintersand other coarse refuse and also to start the upward flow of thestock'over the screen plates, means to rotate said screen to create sufficient centrifugal force to cause said refuse to riserotatable in said vat, an upright shaft passcone, the bottom end of said spout being flared outwardly adapted to deflect the stoc radially over said bottom with suflicient force to start the upward fiow of the stock over. the screen plates, means to rotate said shaft and cone to create centrifugal action to continue the upward flow of the stock towards the tops of the screen plates, means to efiect the axial vibration of the cone, and adjustm able means to maintain the stock at various predeterminedlevels within the cone. 6. An upright rotary pulp screen, including a vat, a hopper-like screen disposed concentrically in the vat, a shaft passing upwardly through the bottom of the vat and supporting and rotating the hopper, means to drive said shaft, a pump actuated by the shaft driving means to reciprocate said shaft and vibrate said hopper, said hopper having -an annular open top and concave bot-tom, said top and bottom being spaced to rovide openings which are closed by incline screen plates, a gravity feed-spout disposedconcentrically in sand hopper, the lower end of V 35 said pipe being expanded adapted to deflect the unscreened stock radially toward the bottom ends of the screen plates with sufficient force to start the upward flow of the stock over said plates, and an annular trough to surrounding the top of the hopper adapted to collect the slivers and other coarse refuse separated from the acceptable pulp and ejected from the hopper by the centrifugal force created by the rotation of the hopper. SI In testimony whereof, I afiix my signature.

JOHN A. WIENER.

Images