US2265936A - Apparatus for treating paper stock - Google Patents

Description

Dec. 9, 1941. a. COWLES APPARATUS FOR TREATING PAPER STOCK Filed March 18, 1940 3 Sheets-Sheet 2 :2: ZVENTOR 41 ,7

Dec. 9, 1941. E. COWLES 2,265,936

APPARATUS FOR TREATING PAPER STOCK Filed March 18, 1940 3 Sheets-Sheet 3 1 :EVENTOR BY I 41 KM Z/VZLQ Patented Dec. 9, 1941 4 UNITED STATES PATENT OFFICE 2,265,936 APPARATUS FOR TREATING PAPER s'rocx Edwin Cowles, Cayuga, N. Y.,lassignor to The Cowles Company, Princeton, N. J., a corporation of New Jersey Application March 18, 1940, Serial No. 324,684

11 Claims. (01. 259-96) This invention relates to apparatus for treat- It is a further object of the present invention ing paper stock, and pertains more particularly to provide a means for removing undesired trash to apparatus for defibering, refining and otherfrom the material being treated.

wise preparing paper stock for use on paper mak- Other objects and advantages of the invening machines. tion will appear hereinafter.

In a prior patent, No. 1,883,597 issued October A preferred embodiment of the invention se- 18, 1932, I described a method of treating paper lected for purposes of illustration is shown in stock in which the stock is contained in a vat, the accompanying drawings, in which,

and is circulated by a'pump which withdraws Fi e 1 S a Ve t cal Sectional view.

stock from the vat and returns it thereto, the re- Figur 2 is a pla vi w of a p rtion of the turned stock being discharged into the vat at mpel er.

high velocity through submerged nozzles. The Figure 3 is a side elevation of one of the imhigh velocity jets discharged by the nozzles exerpeller vanes.

cise a defibering and refining effect on the stock Figure 4 is a section on the line 4-6 of Figdue to the tearing effect of the high velocity jets ure 2.

moving through the relatively stationary body of F gure 5 is a plan view of a portion of the t k i th t, impeller illustrating a modified form.

Subsequently, in Patent No. 2,219,571, issued Fi u e 6 is a section n the line 5-5 f Fi Oct. 29, 1940, I described a different form of apn paratus utilizing the principle ofv my aforemen- Fi 7 i a fragmentary p pl n view showtioned patent. In said patent, however, instead ing One Of the trash P of withdrawing stock from the vat and retum- Referring to h w n a vat or tank l is ing it to the vat through nozzles, 1 provide a, rov d d, p ef a ly cyl n al in s ap The tary impeller which is submerged in the vat, bottom 6f the tank is provided with an aperture which said impeller is provided with open grooves to receive the impeller hereinafter described, and

.so designed as to discharge high velocity jets from the sides and bottom of the apertu e y be the rim of the impeller, which said jets have the enclosed to P e a Su ken chamber 3. The same refining and defibering effect as the jets space between said chamber and the cylindrical discharged from th nozzles i th af r m side wall of the tank may be filled with concrete tipped patent. 4 to provide a sloping surface as illustrated in Subsequently, in application Serial No. 314,107, Figure 1. Such a slopin Surface d ects the I proposed to increase the surface area of the S ock discharged from the impell as hereinstock which is discharged at high velocity by disafter explained, u wa d y alo t e side walls charging the same in the form of a relatively of the tank and assists in maintaining circulathin circular sheet, such as a relatively thin antion in the S o k conta ned in the tank as indinular disk. In the preferred embodiment illus- Gated by arrows in Figure 1. If desired, fixed trated in said applicati thi i accomplished directional vanes 5 may be embedded in the conby mounting multiplicity of vanes on the crete to direct the stock which is discharged from face of an open impeller disk, adjacent the rim the imp in an pwa d directien and to rethereof, said vanes being relatively low and being strain to some extent the circulation in a horiclosely spaced, so that stock is discharged at high zontal plane.

velocity around the entire periphery of the im- An impeller, in the form of a disk I0, is mountpeller in the form of a relatively thin annular ed in aforesaid aperture in the bottom of the disk. The surface area of the discharged disk of stock is very great and consequently the reand ay b rotated in y Suitable manner, as fining and defibering effect is very rapid and by pulley ll, driven by motor l2, operating eflicient. through suitable reduction gears (not shown) The machine disclosed in application Serial mounted in the housing l3.

No. 314,107 was adapted for batch operation, The impeller disk is provided with a multithat is, a batch of untreated material is placed 0 plicity of impeller vanes ll mounted adjacent in the machine, the batch is treated, and the the rim of the disk, said vanes projecting uptreated batch is removed from the machine. wardly from the upper surface of the disk. The It is an object of the present invention to said vanes may be secured'to the disk in any provide an improved machine adapted for consuitable mannerI but in the embodiment illus- --tinuous operation. I trated, the vanes are secured, as by welding, to

tank so as to be surrounded by the chamber 3,

a ring l5 which is set into a groove l formed in the disk, which said ring is held in place by screws l'l. Thus, the impeller is of the "open type, being distinguished from closed" type impellers by the absence of any enclosures, hoods, shrouds, passages or the like which are com-' monly used to increase the efliciency of impellers employed for pumping or circulating purposes, but which are wholly unsuited for defibering paper stock.

In order to avoid stapling of stock on the vanes H, the advancing face I! of each vane is inclined to the surface of the disk and at an angle such that the fibers engaged thereby roll and slide along the face. The angle of inclination should preferably not exceed 30 and is preferably somewhat less, as for example, the angle illustrated in the drawings is approximately 18.

The height of the vanes above the surface of the disk is small relative to the diameter of the disk, and should not exceed a ratio of 1 to 30. For example, using a disk having a diameter of the height of the vanes should preferably be about 1 so that the disk of stock discharged from the impeller will be relatively thin.

The impeller should be rotated at a rate sufficient to discharge the stock at the rim of the impeller at a velocity of at least 1,000 ft. per minute and in some cases at considerably higher velocities, as for example, between 1,000 and 2,000 ft. per minute, the particular velocity selected in excess of 1,000 ft. per minute depending on the toughness of the stock being treated. For purposes of this specification, therefore, the term "high velocity is defined as comprehending velocities in excess of 1,000 ft. per minute, for tests have shown that while some defibering action may be produced at lower velocities, it is not possible to produce completely defibered stock within the limits of practical operation. At lower velocities it has been found that defibering proceeds with reasonable rapidity until the undefibered pieces of stock reach a certain size, after which the rate of defibering is rapidly reduced or defibering action may cease entirely. Even long continued treatment often fails to produce complete defiberization. Using high velocities, as. defined herein, however, defibering action proceeds rapidly to completion.

It is important to maintain proper circulation of the stock at all times in order that all portions of the stock may be repeatedly subjected to the action of the impeller. The preferred type of circulation is that which is in the nature of a vortex or whirlpool comprising circulation in both horizontal and vertical planes. It has previously been stated that the sloping sections 4 of the bottom of the tank contribute to this result in directing the stock discharged from the impeller upwardly along the sides of the tank, and it has also been pointed out that excessive circulation in the horizontal plane may be restrained by fixed directional vanes ,5.

Another contributing feature in this connection is the relative diameters of the impeller and the tank, for it has been found that in order to maintain proper circulation, the diameter of the impeller should be greater than one fourth and less than one half the diameter of the tank.

Still another contributing feature to the maintenance of proper circulation is the supplementary vanes 25 which are also mounted on the upper face of the impeller disk between the vanes i4 and the center of rotation of the impeller. The advancing face 26 of the vanes 25 may be inclined to the face of the disk, as shown, to prevent pieces of stock from stapling thereon. The said vanes initially accelerate the stock at the center of the impeller and move it toward the vanes II which additionally accelerate it and discharge it in disk form as previously described. Since the vanes 25 continually move stock away from the center of the impeller, thus drawing stock down centrally from the top of the tank, they assist greatly in maintaining the vertical circulation which has been found so highly useful in the operation of this apparatus. In continuous operations the consistency of the stock is usually low and the vortical cavity may extend all the way down to the impeller, so that the impeller may be seen from the top of the tank. This vortical circulation causes the undefibered material which is being added continuously, which said material is frequently in pieces of large size which otherwise tend to float on the surface, to be drawn down into the vortex and to be immediately subjected to the defibering action of the impeller.

In order to permit continuous withdrawal of treated material, an outlet conduit 28 is connected to the chamber 3, and means are provided for eifectively controlling the fiow of material from the main portion of the tank to the chamber 3 in order to prevent the withdrawal of undefibered material and trash. Thus, in the machine illustrated in Figures 2 and 3 a restricted passage 3| is provided between the edge of the plate 32 and the outside rim of the impeller. Since the passage 3| lies immediately beneath the disk of stock which is being discharged at high velocity by the impeller, it is virtually impossible for pieces of undefibered material or pieces of trash to enter the passage, since the velocity of the stock discharged from the impeller is much greater than the velocity of the material being withdrawn. The high velocity disk serves as a barrier, therefore, to sweep aside any pieces of undefibered material or pieces of trash which tend to move toward the passage without, however, preventing withdrawal of completely defibered material which fiows out with the water.

However, it is advisable that the trailing ends of the impeller vanes extend across the passage 3! as shown in Figure 3, in order to mechanically dislodge any material which may tend to lodge in the passage, and to clear away any fibers which may staple over the edge of plate 32.

In the form of machine illustrated in Figures 4 and 5, the plate 35 extends into close proximity to the rim ofth impeller and the passage for the withdrawal of defibered material is provided by a multiplicity of perforations 36 in the plate. In this form the perforations are cleared by a wiper 31 secured to the impeller having a curved edge, 38 extending across the plate. The

edge 38 runs in close proximity to the surface of I the plate and repeatedly clears the perforations of any fibers which may lodge therein. In this form of machine the disk of stock discharged from the impeller, being discharged immediately adjacent the perforated plate and sweeping across said plate at high velocity, in itself tends to clear the screen perforations, and in so doing enhances the defibering action since thexdischarged disk is directed directly against any accumulation or concentration of fibrous material which may tend to lodge in the perforations due to their restricted size...

In the continuous operation of such machines, particularly in board mills where waste paper is the material to be defibered, it is desirable to provide for the continuous removal of the trash which is always present in waste paper as supplied to the mill. The trash content of such waste paper is considerable, frequently running as high as 4%. In a machine having a capacity of 200 tons per day, for example, there will be an accumulation of several hundred pounds of useless trash per hour, and unless such trash is removed continuously, frequent shutdowns are necessary. Such trash is of two varieties, heavy materials such as paper clips, tin cans, glass, stones, etc., and lighter materials such as rags, string, rope, etc. For the removal of heavy materials, I provide trash pits 40 located at the periphery of the tank and communicating therewith by means of a chute ll. The bottom of the chute may be provided with an aperture 42 opening into the pit and, controlled by a gate 43 which may be operated by any suitable means.

The circulating movement of the material brings the waste material eventually to a position over one of the pits, and the heavy material drops into the pit. The said pits may be dredged moval. By careful observation of the operation of the machine, I have discovered that the vortical circulation tends to concentrate such trash near the center of the circulation in the vertical plane, approximately in thearea indicated by the reference character T, which said area extends around the tank in annular form. Furthermore, I have discovered that by trailing the end of a rope or rope like member, such as barbed wire, for example, in the tank, the lighter trash materials such as rags, string, rope, etc tend to wind themselves around the trailing end of rope, and in so doing, tend to wrap in other light trash such as pieces of wood, Cellophane, rubber, etc. which in themselves are incapable of winding around the rope end. After an accumulation of such trash has formed, it is possible to withdraw the rope end with the trash clinging thereto. However, I find that by withdrawing the rope end slowly and continuously, the trash will continue to form itself into a rope even after the original rope end has been entirely withdrawn from the tank. This is particularly true if the baling wires customarily used to bind up bales of waste paper are thrown intothe tank with the bales. These wires wind themselves into the rope and provide suflicient tensile strength to prevent the self forming rope of trash from breaking as withdrawn. If desired a reel may be mounted at the top of the tank as a convenient means of withdrawal.

It will be understood that the invention may be variously modified and embodied within the scope of the subjoined claims.

I claim as my invention:

1. Apparatus of the character described, comprising, in combination, a tank, said tank having a chamber in the bottom thereof, animpeller located in said chamber and adapted to rotate in a horizontal plane, the periphery of said impeller being spaced from the sides of said chamber to provide a, passage therebetween, said chamber having an outlet opening for the removal of material from the tank, and means forming part of said impeller adapted upon rotation thereof to discharge material horizontally across the entrance to said passage,

er passages therethrough which are swept by said discharged material, and said chamber having an outlet opening for the removal of material from the tank.

3. Apparatus of the character described, comprising, in combination, a tank, said tank having a chamberin the bottom thereof, an impeller located in said chamber and adapted to rotate .in a horizontal plane, the periphery of said impeller being spaced from the sides of said chamber to provide a passage therebetween, said chamber having an outlet opening for the removal of material from the tank, means forming part of said impeller adapted, upon rotation thereof to discharge material horizontally across the entrance to said passage, and means extending across the entrance to said passage and rotating with said impeller to keep said passage 0 ear.

4. Apparatus of the character described, comprising, in combination, a tank, said tank having.

a chamber in the bottom thereof, an impeller.

located in said chamber and adapted to rotate in a horizontal plane, the periphery of said impeller being spaced from the sides of said chamber to provide a passage therebetween, said chamber having an outlet opening for the removal of material from the tank, a plate lying across the entrance to said passage and partially restricting the same, and means extending across the entrance to the restricted passage and rotating with said impeller to keep said passage clear.

5. Apparatus of the character described, comprising, in combination, a tank, said tank having a chamber in the bottom thereof, an impeller located in said chamber and adapted to rotate in a horizontal plane, the periphery of said impeller being spaced from the sides of said chamber to provide a passage therebetween, said chamber having an outlet opening for the removal of material, a screen lying across the entrance to said passage, and means forming part of said impeller adapted upon rotation thereof to discharge material horizontally across the entrance to said passage.

6. Apparatus of the character described, comprising, in combination, a tank, said tank having a chamber in the bottom thereof, an impeller located in said chamber and adapted to rotate in a horizontal plane, the periphery of said impeller being spaced from the sides of said chamber to provide a passage therebetween, said chamber having an outlet opening for the removal of material, a screen lying across the entrance to said passage, means forming part of said impeller adapted upon rotation thereof to discharge material horizontally across the entrance to said passage, and means moving in close proximity to said screen to clear the openings thereof.

7. Apparatus of the character described, comprising, in combination, a vertically disposed cylindrical tank, an impeller located in the bottom of said tank and adapted to rotate in a horizontal plane, a vertically disposed trash pit mounted adjacent said tank, said trash pit being open at the top for the removal of trash deposited therein, and an inclined chute connecting the bottom of said tank with said trash pit adapted to permit gravity separation of heavy trash from the tank.

8. Apparatus of the character described, comprising, in combination, a vertically disposed cylindrical tank, an impeller located in the bottom of said tank and adapted to rotate in a horizontal plane, said impeller having a diameter less than one-half the diameter of the tank, a vertically disposed trash pit mounted adjacent said tank, said trash pit being open at the top for the removal of trash deposited therein, said tank having an aperture in the bottom immediately adjacent the side wall of the tank, and an inclined chute extending from said aperture to said trash pit adapted to permit gravity separation of heavy trash from the tank.

9. Apparatus of the character described, comprising in combination, a tank, a rotary impeller submerged in said tank, means forming p rt of said impeller for discharging stock at high velocity around the entire periphery of the impeller in the form of a relatively thin-annular disk, said tank being provided with a chamber spaced outwardly from the periphery of said impeller, a

screen lying across the entrance to said chamber, said screen being located immediately below said discharged disk of stock and continuously swept thereby, said chamber having an outlet 0 for the continuous withdrawal of treated stock from said tank.

10. Apparatus of the character described, comprising in combination, a tank, a rotary impeller submerged in said tank, means forming part of said impeller for discharging stock at high velocity around the entire periphery of the impeller in the form of a relatively thin annular disk, said tank being provided with an annular chamber concentric with said impeller and spaced outwardly therefrom, a screen lying across the entrance to said chamber, said screen being located immediately below said discharged disk of stock and continuously swept thereby, and said chamber having an outlet passage for the continuous withdrawal of treated stock from said tank.

11. Apparatus or the character described, comprising, in combination, a tank, an impeller disk mounted for rotation in said tank, said impeller disk having a plurality of vanes offset from its upper surface and freely exposed to the material in the tank and adapted upon rotation of said disk to discharge material outwardly therefrom, a circular screen mounted in said tank concentric with said impeller and adapted for the continuous withdrawal or material from said tank, and a wiper mounted on said impeller for rotation therewith and moving in close proximity to the surface of said screen to clear the openings thereof.

EDWIN COWLES.

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