US1731193A - Apparatus for straining pulp - Google Patents

Description

Oct. 8, 1929. B. DECKER APPARATUS FOR STRAINING PULP v Filed Dec. 27, 192'? 2 Sheets-Sheet 1 Attorneys L. B DECKER 1,731,193

APPARATUS FR STRAINING PULP 2 Sheets-Sheet 2 Filed Dec.. 27, 1927 Emmi/ Attorneys Patented Oct. 8, 1929 UNITED STATES LElMIUEL B. DECKER, OF KENOGAMI, QUEBEC, CANADA APPARATUS FOR STRAINING PULP Application filed December 27, 1927. Serial No. 242,761.

uid embodying the formation of an initial basic covering or matting of relatively coarse stock, about the exterior of which is gathered the finer fibers separated from the liquid.

Another object of the invention is the provision of a process and apparatus wherein the coarse matting stock may be obtained directly on the'machine so as to obviate the necessity of drawing the same from-the system.

Still another object of the invention is the provision of an apparatus which maybe efficiently employed as a stock thickener or decker.

A further object of the invention is the provision of an apparatus of the above character which will be relatively simple and durable of construction and economical in operation.

Still another object of the invention is the provision of a machine of the above type which can be manufactured at a comparatively low cost.

Other objects and advantages of the invention will become apparent as the description progresses.

In the accompanying drawing forming a part of this specification and in which like reference characters are employed to designate' corresponding parts throughout the same:

Figure 1 is a top plan view of tlie assembled machine constructed in accordance with my invention, 1

Figure 2 is a vertical longitudinal section through the same,

Figure 3-is an enlarged longitudinal section through the cylinder,

. Figure 4 is an end elevation of the cylinder taken on the line 4-4 of Figure 3,

Figure 5 is an enlarged detail section, and Flgure 6 1s a similar View.

Referring to the drawings, wherein for the purpose of illustration is shown a preferred embodiment of the invention, the numeral 10 generally designates a water receiving vat which is preferably of rectangular form and open at the top. The sides of the vat are provided with transversely opposed recesses designed to receive therein a cylinder supporting shaft 11. The forward wall of the vat is formed with an opening adjacent the bottom thereof designed to receive one end of an inlet conduit 12 through which the white water is discharged into the vat. A vertical baflle plate 13 is secured to the bottom of the vat adjacent the inlet. 12 to break thecurrent of the water discharged through theinlet.

The cylinder supporting shaft 11 is of tubular construction and is divided adjacent one end by a transverse partition 14 to provide a vacuum chamber atone end and .a ventilating chamber at the opposed end. A pair of diametrically opposed partition win s 15 are formed on the exterior of the sha t 11, these wings projecting radially in a horizontal plane and preferably having a tapered cross section. Secured to the tubular shaft 11 and depend; ing downwardly therefrom are a plurality of tubes 16 communicating with the interior of the shaft at one side of the partition 14 to rovide a suction manifold. At the opposed side of the partition 14 is mounted an upwardly extending vertical tube 17 communicating with the ventilating side of the shaft to pro vide a vertical ventilator.

Positioned concentrically about the shaft 11 is a relatively large cylindrical drum 18 enclosed at its ends by removable cylinder heads 19 slidably fitted on the ends of the shaft 11.- The peripheral edge of the heads is rabbeted to provide .a reduced portion adapted to be snugly fitted in the ends of the cylinder 18 and a diametrically enlarged flange adapted to abut the end edges thereof. The heads are secured on the cylinder by means of axially extending screws 20 projecting through openings 'invthe flanges of the heads and threaded in the ends of the cylinder. Formed integral with or secured to the outer sides of the heads adjacent the peripheral edges thereof are annular external spur gears 21, the purpose of which will be later described. The intermediate exterior surface of the cylinder is'preferably recessed and adapted to receive a spiral wire 22 about the exterior surface of which is secured a foundation screen wire 23 of relatively coarsamesh,

approximately fourteen mesh. An outside straining wire 24 is secured over the founda; tion wire 23, the outside wire being of finer mesh, preferably about sixty mesh. The wall of the cylinder 18 is perforated to provide a plurality of longitudinally arranged apertures 25, each successive line of apertures being arranged in staggered relation in conformity with the spiral winding of the=wire 22. As shown to advantage in Figure3, the cylinder is disposed on the shaft llwithin the vat 10, the heads of the cylinder being spaced from the interior sides ofthe vat and rotatably fitted on the shaft by means of suitable ball or roller bearings. A suitable packing 26 is also snugly fitted about the shaft 11 to prevent leakage of the water through the heads.

As illustrated in Figure 2, the wings 15 are formed so that their outer edges terminate adjacent the interior periphery of the cylinder while the vertical tubes 16-and 17 terminate adjacent the upper and lower portions thereof. The shaft 11 is rigidly held in fixed position in the vat by means of flanges 27 secured about the shaft and attached to the sides of the vat. Thecylinder is rotatable about the shaft and is driven by a pair of.

pinion gears 28 fixed on a horizontal'drive shaft 29 and arranged to mesh with annular gears 21 mounted on the outer sides of the cylinder heads. The shaft 29 may be arranged in the upper rear portion of the vat, as indicated at Figure 2, and driven by any suitable motor.

Rotatably supported in a-horizontal position parallel with the cylinder is a couch roll 30 arranged to contact with the upper portion of the exterior cylinder screen. This'roll is covered with a felt or other suitable jacketing, as it is customary, to remove the stock accumulated on the cylinder screen,

The pulp isremoved from the couch roll 30 and discharged into a suitable receiver by means of an angularly supported blade 31, commonly termed a doctor, arranged so that its upper bevelled edge contacts with the couch roll while the lower edge is inclined Y downwardly to discharge the stock into the receiver.

Removabl mounted in the upper forward portion of tie vat for supplying a quantity of coarse pulp during the operation of the strainer, is a stock trough 32 supported in horizontal position upon apair of bars 33 fixed to the opposed inner sides of the vat and provided with an intermediate vertical partition 24 adapted to form a bafie for the stock. The inner ends of the sides of the trough 32 are cut inarcuate form. so as'to be positioned snugly against the upper portion of the cylinder, as indicated in Figure 2. The bottom of the trough terminates a predetermined distance from the cylinder, as clearly illustrated in the drawing, to provide a feed slot by means of which the coarse pulp discharged on to the cylinder screen is regulated so. as to form a foundation matting of coarse stock of predetermined thickness. A conduit 35 is a connected to and communicates with the interior of the trough 32, this conduit'being provided with a regulating valve 36 for controlling the supply of coarse stock to the trough.

Under the present practice, it is customary to mix a. quantity of coarse stock with the white water during the straining operation, the coarse pulp beingsecured from the output stock of the system. This may also be efii'ected in the present machine, the conduit 35 being in communication with a stock container for selectively securing a predetermined quantity of coarse pulp for the forma- 7 tion of the foundation matting. It is also contemplated, however, to provide means whereb the coarse stock may be obtained directly rom the white water employed in the vat, this being accomplished by providing an inclined strainer embodying a strainer frame 37 formed with a receiving trough 38;, at the upper end. A transverse baiile 39 is mounted in the trough 38' and arranged so that the wao ter will be initially discharged through the lower portion of the trough and then directed upwardly by means of a vertical plate 40 extending partially upward from thebottom of the trough. -An inclined sifting screen 41, 105 of suitable mesh,.is mounted in an intermediate position in the frame and arranged so that the coarser fibers from the water will be delivered downwardly into the feed trough 32, the water and finer fibers will pass through the screen and will be discharged ,downwardly in a'lower conduit d2 into the 'vat. With this construction, a suitable supply of coarse ifibers can be secured from the white water to form the foundation matting and 115 obviate the necessity of v withdrawing the coarser stock from the system.

While the apparatus is particularly designed to be employed as a save-all for the recovery of the fine fibers from the white 12 water it is readily apparent that the same may be efliciently employed as a stock thickener, often called a decker, for strainin the stock during its customar course throng the system. In this particular application, the 125 inclined strainer and trough 32 may be removed or entirely eliminated from the construction to provide a stock thickener having an exceedingly eflicient induced suction whereby the pulp fibers may be eficiently ,130

drawn on to the cylinder in the thickening operation.

An important feature of the present process is the formation of an initial layer or matting of relatively coarse pulp fibers on the strainer screen. The finer fibers recovered from the white water are then drawn about the exterior surface of the matting and thus strained. In this manner, it is possible to reclaim practically the entire fine fiber residue in the white water.

i In the operation of the apparatus described in the foregoing, a suitable vacuum pump1s connected with one end of the tubular shaft 11 in communication with the manifold tubes 16 arranged at one side of the partition 14. The opposite end of the shaft is open to the atmosphere. The white water is delivered into the vat through the inlet 12 and is preferably maintained at a level designated at 43 below the outlet in the upper end of the vent tube 17. A supply of coarse stock is discharged into the trough 32 by the application of-the inclined strainer mounted thereon or,

if desirable, directly through the supply pipe 35. The cylinder is then uniformly rotated at a predetermined speed. The operation of the vacuum pump will produce a suction through one end of the shaft 11 and manifold tubes 16 to exhaust the water from the lower portion of the cylinder. Due to the particular arrangement of the wings 15, the induced suction will be of greater efiect in the lower half of the cylinder inasmuch as the water will form a water seal between the outer edges of the wings and the opposed sides of the cylinder. In the upper end of the cylinder, above the water line, the admission ofair through the ventilator chamber and tube will offset the suction so that the stock may be readily removed.

During the operation of the machine, the cylinder rotates in the direction indicated by the arrow in Figure 2, the coarse pulp fibers being drawn on to the exterior screen of the cylinder by the induced suction and the finer fibers from the white water adhering to the exterior surface of the coarse fiber matting during the continuing rotary movement of the cylinder. When the-stock drawn on the cylinder reaches a position above the water level and immediately prior to the engagement with the couch roller the induced suction created by exhausting the water from the cylinder is rendered practically non-efiective by the introduction of air in the upper portion of the cylinder thus enabling the couch roll to readily gather the stock from the surface of the cylinder. The upper portion of the cylinder moving in contact with the couch roll is then thoroughly washed as is customary. It will be particularly noted that the coarse stock supplied through the trough 32 is drawn on to the washed portion of the cylinder as it w rotates below the water level. By this construction, the coarser fibers are initially positioned directly on to the exterior straining screen and the fine fiber residue in the white water subsequently drawn about the matting so that an exceedingly high proportion of the residue is recovered.

Thus, by the present process a foundation covering or matting of-coarse pulp fiber is formed by induced suction upon the straining screen prior tothe collection of the finer fibers recovered from the white water. Furthermore, the supply of coarse fibers may be secured directly upon the apparatus without the necessity of withdrawing the same from the treated stock of the system.

It is to be understood that the form of my invention herein shown and described is-to be taken as a preferred example of the same, and that various changes as to the shape, size, and arrangement of parts maybe resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described my invention, I claim 1. In an apparatus for straining pulp fibers including a vat adapted to contain white water, a hollow shaft extending through the vat, the said shaft being divided to form separated chambers, a perforated cylinder mounted for rotary movement about the said shaft, suction tubes connected to and communicating with one chamber of the shaft and depending downwardly within the cylinder for exhausting the water from the cylinder, a ventilating tube connected to the shaft and communicating with the opposed 01121111 ber extending vertically upward within the cylinder to supply air into the upper portion of the cylinder above the water line, and means for removing the stock drawn upon the exterior of the cylinder.

2. In a straining apparatus of the character described, a vat, a hollow shaft supported in stationary position in the vat, the said shaft being divided by a transverse partition to form a suction chamber at one end and a ventilating chamber at'the opposite end, a perforated straining cylinder rotatably mounted on the shaft enclosed at its ends, a plurality of suction tubes connected to the vacuum chamber of the shaft and depending downwardly within the cylinder, the said tubes connecting with said vacuum chamber and open at their lower ends, a ventilating tube secured to and communicating with the ventilating chamber of the shaft and projecting upwardly therefrom, the upper end of the said ventilating tube being open and terminating adjacent the inner tube portion of the cylinder, and a pair of diametrically opposed wings extending radially from the shaft in.

3. In combination, a vat, a rotary straining cylinder, a shaft on which said cylinder is supported, a pair of wings extending from said shaft adapted to divide the interior of the cylinder into a pair of opposed compartments, means for exhausting fluid from one of the compartments, and means for introducing air to the opposed compartment.

4. In combination a vat, a rotary straining cylinder, a shaft on whichsaid cylinder is supported, partitions projecting outwardly from said shaft and terminating adjacent the interior walls of the cylinder, means for exhausting fluid from one compartmentin the cylinder through the shaft, and means for introducing air into a compartment in the cylinder through said shaf 5. In combination, a vat, a rotary straining cylinder, a shaft on which saidcylinder is supported, a pair of horizontally-extending wings projecting from the shaft and terminating adjacent the inner Wall of the cylinder, means for exhausting the fluid from the lower interior portion of the cylinder, and

means for introducing air into the upper interior portion of the cylinder.

In witness whereof I have hereunto set my hand.

LEMUEL B. DECKER.

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