US1766000A - Pulp-stock vat - Google Patents

Description

June 24, 1930. H. PARKER PULP. STOCK VAT Filed uovf'zz, 1928 0 4 Sheets-She et 'l H. PARKER PULP s'rocx VAT Filed Nov. 22, 1928 4 Sheets-Sheet 2 H- PARKER PULP STOCK VAT June 24, 1930.

Filed Nqv. 22, .1928 4 Sheets-Sheet 3 H. PARKER.

PULP- STOCK VAT June 24, 1930.

Filed Nov. 22, 1928 4 Sheets-Sheet 4' Patented June 24, 1930 UNITED STATES PATENT OFFICE,

HOWARD PARKER, OF BERLIN, NEW HAMPSHIRE, ASSIGNOR T0 BROWN COMPANY, OF BERLIN, NEW HAMPSHIRE, A CORPORATION OF MAINE PULP-STOCK VAT Application flied November 22, 1928. Serial No. 321,080.

This invention relates to improvements in vats for cylinder molds such as are-used for forming webs of wet cellulosic pulp from an aqueous suspension of such pulp. In

5 forming a wide web of pulp on a cylinder mold there is liable to be a variation across the sheet in the thickness of the web picked up. This may be due to local eddy currents in the pulp stock adjacent to the cylinder, or

10 to back-wash where the surface of the cyllnder emerges from the stock in the vat, or to other causes. The resulting web may be formed with longitudinal streaks of pulp which are thicker or thinner than the remainder of the sheet, or the marginal area's may be thicker or thinner than the central portion. While the average thickness across a plup webihas been previously controlled by regulating the difference of level between the stock outside the cylinder and the whitewater inside no provision has heretofore been made r6 locally controlling the deposition of pulp on the cylinder. It is an object of this invention to facilitate the production of pulp webs the thickness of which can be locally controlled so as to obtain a substantially uniform thickness across the web, 01' to obtain a web having any desired variation of thickness from one edge to the other. According to the invention, such local control of web thickness is effected by controlling at various points the agitation of the stock adjacent to the cylinder. This may be done, as hereinafter described, by directing the flow of stock in the vat so as to vary its nation locally against the surface of the cyl- 1n er.

For a more complete understanding of the invention, reference may be had to the of which, I

Figure 1 is an end elevation of apparatus embodying the invention.

Figu re 2 is a side elevation of the same. Figure 3 is a plan view of the sam 3. Figures 4 and 5 are fragmentary details of portions of the apparatus shown in Figure 1. a

Figure 6'is a section on the line 66 of Figure 2. v

following description, and to the drawings,

7 is a section on the line 77 of Figure 13 shows in transverse section a further modification of the invention.

Figure 14 is a plan view of the same. Referring to the drawings in detail, a cylindrical mold 20 may be mounted on suitable bearings 21 to rotate on a horizontal axis within a container 22 which, in turn,- is located within a vat 23. The cylinder 20 may have the usual construction well known 1n the art comprlsing a wire screened surface 24 supported by suitable frame- Work 25. Within the vat 23 ,is provided a partition 26 which with end walls of the vat foi'msthe inner container 22 in which the cylinder mold 20 rotates. A supply compartment 27 may be provided at one side of the container 22. This compartment may be in a separate tank positioned adjacent to a side of the vat 23 or may be included in the vat, and separated from the remainder 'ofthe vat as by a suitable partition. At

the other side of the container 22 a discharge chamber 28 may be provlded to receive stock which overflows from the pool.

in the container 22. As shown in Figure 6, thestock in the supply compartment 27 is normally maintained at a higher level than the pool in the container 22,'the latter being, in turn, at a higher level than the stock in the discharge chamber 28. The pulp stock may be supplied through the bottom of the supply compartment as by a pipe 29. The stock entering the lower portion of the compartment 27 flows upwardly and spills over an upper side edge of the partition 26, this edge being made 'vertically adjustable, if desirable, as shown in Figure 13, to regulate the stock level in the compartment 27. In order to ensure a proper distribution of the stock entering through the pipe 29, in the compartment 27 may be mounted a hollow distributing roll 30 having perforations in its periphery. This roll may be rotated during the operation of the apparatus as by a suitable motor 31. Suitable baflles 32 may be mounted beside the roll 30 so as to force all the stock entering through the pipe 29 to pass through the rotating roll 30. The rotation of the roll thoroughly agitates and mixes the stock passing therethrough so that the stock in the upper portion of the compartment 27 which spills over the edge of the partition is of fairly uniform consistency. The stock in the inner container 22 partially immerses the cylinder 20.

During the operation of the apparatus the stock immediately adjacent to the surface of the rotating cylinder is drawn against the surface of the cylinder by the difference of pressure inside and outside the cylinder due to the level of the white-water within the cylinder compared with the level of the stock outside the cylinder. As the difference ofpressure presses the stock against the surface of the cylinder, the fibers of the stock are depositedon the wire screen as the water of suspension thereof passes through the meshes of the screen to the interior of the cylinder. In this way a web 'of pulp is formed on the surface of the cylinder in a manner well known in the art. In practical operation there is often a tendency on the part of the pulp to form in streaks of varying thickness, ,these streaks being probably due to eddy currents set up 1n the pool of pulp stock adjacent to the supply compartment fromyvhich fresh pulp stock is continually fed into the pool. In order to produce an even sheetwith substantially uniform thickness from one side to the other or to produce a sheet having certain desired irregularities of thickness, means are provided for locally controlling the thickness of the pulp mass deposited on the cylinder.

To this end a series of separated channels or ducts 33 are provided which, as shown in Figure 6, communicate with the upper port1on of the supply compartment 27 and extend around and under the container 22,

opening into this container atthe discharge side thereof in such a way that pulp stock flowing therefrom will be projected against that portion'of the. surface of the rotating cylinder which is about to emerge from the pool of stock. These ducts 33 may be formed in any convenient way, as, for example, by

- a series of partition members 34 which extend around. and under the container 22. The streams of pulp stock flowing through the ducts 33 cause local agitation of the stock in the pool 22 which is adjacent to the surface of the cylinder about to emerge from the pool. This agitation at the surface of the cylinder tends 'to retard the further deposit of fibers on the submerged surface of fibefs will be more loosely held to the wire than the inner fibers and will be readily washed off, reducing the thickness of the web to normal. As many of the outermost fibers on the web are liable to be washed off by the disturbance or back-wash of the cylinder at the point where its surface emerges from the pool, the consistency of the stock in that portion of the pool is usually somewhat thicker or heavier than the consistency of the stock which'is supplied to the pool. The introduction of a stream of stock of normal consistency opposite a portion of the length of the cylinder surface emerging from the pool tends to push the heavier stock away from such point of introduction. This heavier stock is thus adjacent to the remainder of the length of the cylinder and tends to thicken the portions of the web which are not opposite the introduced stream. Thus for example if the against the central portion of the emerging web tends to push the heavier stock toward the ends of the cylinder so that a heavier web is picked up by the end portions.of the cylinder surface.

The amount of agitation at various points along the surface of the cylinder 20 may be controlled by regulating the streams flowing through tlie several ducts 33. To this end a gate 35 may be placed over the mouth of each duct 33 so that by regulating the opening of the gate 35 the flow of pulp stock through each duct 33 can be controlled. Mechanism for operating,v the gates 35 may be as shown in Figures 1 to 3. Each gate 35 is hinged as at 36 and is attached to a lever 37 as by a suitable link 38. The lever 37 and link 38 are so arranged that rocking of'the lever will open or close the gate. In order to set the gate in an adjusted position, the further end of the lever 37 maybe securc-d to anadjusting device illustrated in end of the arm 37. The lower endof the screw-rod 41 may be formed with or secured to an eccentric-strap 43 which is mounted on an eccentric bar 44 j ournaled in a bracket 45 extending from the side of the vat. It is apparent from Figure 5 that rotation of the sleeve 39 will result in upward or downward movement of the bearing 42, rocking the lever arm 37 and opening or closing the valve 35. By supplying a lever 37 and adjusting sleeve 39 to each 'one of the gates 35, as shown in'Figures 2 and 3, the flow of stock through any of the ducts 33 can be regulated independently of the flow through the other ducts. In order to effect a simultaneous adjustment of all the gates 35, the eccentric shaft 44 may be turnedv as by a suitable handle 46 or other means as desired. Rotation of the eccentric shaft 44 raises or lowers the individual valves by a uniform amount. In order to prevent backward slipping of this mechanism a ratchetwheel 47 cooperates with a pawl48.

In operating the machine, the pulp may be introduced through the supply pipe 29 and may be passed upwardly through the supply compartment 27, being distributed by the roll 30. The pulp reaching the top of the pool in the supply compartment spills over the edge of the container wall into the container 22. Some of this stock is deposited on the roll, the white-water from the deposited stock being led off from within the cylinder by any suitable means. The remainder of the stock flows around the periphery of the roll and discharges into the discharge compartment 28, as indicated in Figure 6. If, upon operating the machine, there are streaks of pulp in the web which are thicker than other streaks in theweb,

this may be compensated for by opening the gates 35 a sufficient amount to permit a flow of pulp stock around under the tank independently of the stock within the tank.

This stock is discharged'into the tank so as to flow against corresponding portions'of the surface of the cylinder mold opposite thereto. By opening suitable gates so as to permit such streams to discharge opposite the portions of the cylinder on which the strips of extra thickness are being formed, the agitation caused by the stream from the duct tends to reduce slightly the thickness of such streaks and to build up the thickness of the remainder of the web, thus smoothing out the web to a uniform thickness.

In order to keep the level of.the pool of pulp stock in the container 22 substantially constant, an excess of stock is fed thereinto over the right hand edge ofth-e partition 26, the excess overflowing into the discharge chamber 28 whence it may flow through suitable openings 49 into auxiliary tanks 50 located at the ends of the container 22 and separated therefrom by a partition wall .sistency.

or other portion of the mill apparatus. A

considerable portion of the white water, together with the excess stock which flows into 'the discharge chamber 28, may be led through a regulating pipe 54 which joins the stock supply pipe 55 and leads-to the supply pump 56 which feeds the stock to the supply tank 27 The consistency of the stock supplied to the tank 27 may be regulated by'suitable valves 57, 58, one of these valves being .in the stock supply line, the other being in the recirculating pipe '54. By this arrangement the excess stock from the container 22 is at once recirculated together with suflicient' white water to dilute the fresh stock supply to the proper con- In order to facilitate cleaning of the ducts 33, each of these may be provided with an opening at its lowermost point, these openings being normally closed as by a plate 59 extending longitudinally beneath the vat 23 and having therethrough a number of openings 60 which may be moved simultaneously into or out of register with respective openings in the ducts 33. For the operation of the plate 59 a suitable hand lever 61 may be pivoted as at 62, this lever being secured to a couple of ears 63 on the end of the plate 59. By rocking the lever 61 the openings 60 may be brought into registry withi the openings in the'ducts 33, thus permitting the contents of the ducts to drain out and also permitting the sluicing of the ducts in order to wash them'out.

. A modified embodiment of the invention is illustrated in Figures 10 to 12 inclusive.

From each of. 'these small compartments, WlllCll are arranged in a row extending parallel to the axis of the cylinder, as shown in Figure 11, the stock pours through an openiilg 69 in' the. partition '66 into the container 65. The amount of stock thus supplied to the container 65 at any point along the length of the cylinder may be locally regu-- lated as by a suitable gate 70 which may 65 may enter the container adjacent to the be held. in any position as by mechanism illustrated in Figure 10 and consisting of a lever arm 37 to one end of which the gate is connected as by a link 38, the other end being adjustably secured to a threaded rod 41 eccentrically mounted at one end on a shaft 44. As hereinbefore described, this construction permits the individual adjustment of each gate 70, and also the simultaneous adjustment of all the ates together, the latter adjustment being e ected through rotation of the eccentric shaft 44. The local regulation of supply of stock into the container 65 may be used to govern the agitation of the stock adjacent to the cylinder at any point along the line where the surface of the rotating cylinder enters the pool of stock. Thus the thickness of the web initially picked up by the cylinder may be regulated. Means are also provided for 10- cally controlling the thickness of the web lifted from the pool by the cylinder, such means as shown comprising a series of gates 71 adapted to fit over suitable openings 72 through which stock from the supply pipe 67 rising through a distributing roll 73 in the compartment, to the left of the container point where the surface of the cylinder 20 leaves the pool of stock. Above the distributing roll 73 the compartment is divided into small compartments by a number of transverse partitions 74, similar to the partitions 68 on the other side of the vat, each of the small compartments being provided with a gate 71. The openings 72 may be at a somewhat lower level than the openings 69.

Stock entering through the openings 72 thus enters at approximately the level of the pool within the container 65, so that the flow is directed more horizontally than downwardly as would be the case if the openings 72 were higher so as to allow the entering stock to fall into the pool. The current of stock entering through each opening 72 flows toward the cylinder and tends to neutralize the back-wash, that is,,the back-flow into the pool, of stock which is carried above the surface of the pool by the emerging surface 5 of the cylinder 20. The back-wash has a tendency to wash off some of the outer and more loosely held fibers of the web which 1121s been picked up by the cylinder. By

vmmimizin the back-wash through the agency 0 streams of stock introduced through the openings 72, a thicker and more 'eyen web is obtained on the surface of the cylinder as it leaves the pool. --The local regulation of the streams of stock admitted through the openings 72 also permits the localization of the heavier stock at desired points of the emerging cylinder surface to build up thethickness of the web at such oints. The white water from the interior of the roll 20 is disposed of as hereinbefore described in connection with Figure 7, a portion of the white water being recirculated to be mixed with the fresh supply of incoming stock, the remainder being led away through an overflow pipe 53.

\ A further modified form of the invention is illustrated in Figures 13 and 14. .As in by a rack 78 and pinion 79. The portion of the stock which flows toward the left is distributed as by a perforated roll 73 and enters a series of compartments formed by a series of partitions 74. The stock from these compartments flows through individual openings 72 which are controlled as by gates 71, the amount of opening of each of the gates being regulated by any suitable apparatus such as has been hereinbeforedescribed. In this form of the invention local regulation of web thickness is effected near thepoint where thesurface of the rotating cylinder leaves the pool of stock, the local agitation serving to offset the backwash onthe cylinder and to tend to wash away some of the outermost fibers on the web of pulp picked up by the cylinder.

The pulp formed by the cylinder may be removed by any. suitable means such as a traveling felt 80 which may be pressed against the upper portion of. the cylinder 20 as by a couch roll 81 in a manner well known in the art.

An embodiment of this invention having been thus described it should, be evident to those skilled in the art that various changes and modifications might be made therein without departing from its spirit or scope as defined by the appended claims.

I claim:

1. Apparatus of the class described comprising a vat to contain a pool of pulp stock, a cylinder mold rotatably mounted therein for partial immersion in said pool, and means for locally agitating the stock at spaced points adjacent to the submerged surface of the cylinder, and means for selective regulation of stock agitation at the several said points. I

2. Apparatus of the class described comprising a vat to containa pool of pulp stock, a cylinder mold rotatably mounted therein for partial immersion in said pool, means for .locally agitating the stock at a succession of points arranged lengthwise of the cylinder and in that portion-of the pool from which the surface of the rotating cylinder emerges from the pool, and means for controlling said agitating means individually at the several said points.

3. Apparatus of the class described comprising a vat, a cylinder mold rotatable therein, means'for maintainin -a pool of pulp stock in said vat at a esired level partially submerging said cylinder, means for, supplying stock to said pool where the surface of the rotating cylinder enters the pool, and means for directing a stream of stock into said pool and against the portion of the rotating cylinder which is about to emergefrom the pool.

4. Apparatus of the class described comprising a vat to contain a pool of pulp stock, a cylinder rotatably mounted therein for partial immersion in said pool, means for directing a flow of stock against the portion of the submerged surface of the cylinder which'is about to emerge from the pool, and means for locally regulating said flow of stock at a succession of points arranged lengthwise-of the cylinder.

5. Apparatus of the class described comprising a vat to contain a pool of pulp stock, a cylinder mold rotatably mounted therein for partial immersion in said stock, and means for locally regulating-the thickness of the web formed on the cylinder, said means including means for directing parallel streams of stock against that portion of the surface of the rotating cylinder which is about to emerge from the pool and means for independently regulating the flow of each of said streams.

6. Apparatus for forming a pulp web, comprising a vat, a c linder mold rotatable. therein, and means or locally controlling the thickness of the web icked up by the cylinder, said means indl members in said vat .arranged perpendicularly to the axis" of the cylinder and means for regulating independently the stock flowing between each successive pair of partition members.

7. Apparatus of the class described comprising a vat for pulp stock, an inner ,con-' tainer within said vat to hold a pool of "stock, a cylinder mold rotatably mounted.

in said inner container for' partial immersion in sald pool, a supply compartment in said vat atone side of said container, means for maintaining the stock. in said supply compartment at a higher level than said pool, a series of ducts leading from said supply compartment and opening into said container at points opposite that portionof the surface of said rotating cylinder which is about to emerge from the pool, said ducts being arrangedside by side along the length v of thecylinder, and means for independently regulating the flow through each of said 35 ducts,

uding partition 8. In combination with a pulp stock vat and a cylinder mold revoluble therein on'a horizontal axis, means for introducing stock into said vat at a substantially uniform rate along the length of the descending surface of the c linder, and means for 10- cally agitating the stock in the vicinity of the ascendin surface of the cylinder.

9. In com ination. with a pulp stock vat and a cylinder mold revoluble therein on a horizontal axis, means for introducing stockof the cylinder, means for directing a series of streams of stock against points distributed lengthwise of the ascending surface of the cylinder, and means for individually controlling said streams.

11. In combination with a pulp stock vat and a cylinder mold revoluble therein, and means for maintaining a'pool of pulp stock in said vat in which the cylinder is partially submerged, said pool maintaining means includingan auxihary stock tank with horizontal dam between it and the poo over which a supply of stock may spill into the pool at points adjacent to the immerging surface of the cylinder, a series of ducts extending from said auxiliary tank and to the' emerging surface of said cylinder, and means for individually regulating said ducts to control the flow of stock therethrough. i 3

12. In a pulp stock vat for a cylinder mold, means for supplying stoclnthereto along one side thereof, the rate of flow of the incoming stock being substantially uniform along said. side, additional means for supplying stock to said vat along the opposite side thereof, and means for regulatin said additional means to control locally the flow of stock entering the vat at various points along said opposite side.

13. In a pulp stock vat for a cylinder mold, an auxiliary supply tank adjacent to one side of said vat, a horizontal supply dam between said vat and tank over which stock may s ill into the vat, a discharge dam along t e opposite side of the vat, at a lower level than said supply dam, a series of ducts leading from said auxiliary tank andopening into-the opposite side of said opening into said pool at points adjacent vat at points distributed along the length of the vat, means for individually regulating the flow in said ducts, and means for simultaneously and uniformly altering the flow in all said ducts. 1

In testimony whereof I have aflixed my signature.

HOWARl PARKER.

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