US3043526A

US3043526A - Apparatus for pulping paper stock

Info

Publication number: US3043526A
Application number: US758097A
Authority: US
Inventors: Cowles Edwin
Original assignee: John W Bolton and Sons Inc
Current assignee: John W Bolton and Sons Inc
Priority date: 1958-08-29
Filing date: 1958-08-29
Publication date: 1962-07-10
Anticipated expiration: 1979-07-10

Description

July 10, 1962 Filed Aug. 29, 1958 E. COWLES APPARATUS FOR PULPING PAPER STOCK 3 Sheets-Sheet l INVENTOR. EDW COVVZE'S' BY 7 .2mm PM ATTORNEYS July 10, 1962 E. cowLEs 3,043,526

APPARATUS FOR PULPING PAPER STOCK Filed Aug. 29, 1958 3 Sheets-Sheet 2 Fig. 3. 24 2Q 4 Hl 1 a 23 Q J 7 l l 43 41 I l 32 4,7 45 39 I 3 I 1}: 51 I m .37 :L

I 24 I 1 j 25 41 43 42 l j l ,/,5/4 1 39 I i j; 37

F ig. 4.

INVENTOR. Epmzv C'OI/VLES BY PM PM ATTORNEYS ly 10, 1962 E. cowLEs 3,043,526

APPARATUS FOR PULPING PAPER STOCK Filed Aug. 29, 1958 3 Sheets-Sheet 3 F 6. 62 INVENTOR.

' i EDWIN cowzEs I BY 7 .2mm *TWM ATTORNEY/S 3,l43,526 APPTUS F0112 PULPING PAPER STQCK Edwin Cowles, New York, N.Y., assignor to John W. Bolton & Sons, lnc., Lawrence, Mass., a corporation of Massachusetts Filed Aug. 29, 1%8, Ser. No. 758,097 9 Claims. (Cl. 241-46) This invention relates to an apparatus for pulping paper stock including the making of paper stock from waste paper, virgin pulp and the like. i

The invention pertains to machines of the general type illustrated in my prior Patents 2,351,492 and 2,557,174 wherein an impeller rotates on a vertical axis in the bottom of a tank to create a vortex in the paper stock while discharging stock from the periphery of the impeller, thereby circulating and pulping the paper stock.

It has heretofore been proposed to mount such an impeller in a volute chamber at one end of a midfeathered, Hollander type, beater the peripheral discharge from the impeller being directed up and around the parallel reaches of the beater until the stock cascades down into the impeller casing.

I have found that in such a relatively shallow tank with large area the vortex which forms is so large that the pulping and defibering action is impaired. The solution to this problem is to use a deeper tank, having less area which also improves the circulation and dumping characteristics of such machines while retaining sufiicient vortexing action for efiicient submergence of floating materials.

l have found that a tank of considerable area such as -a Hollander type beater requires an impeller of considerable area to maintain a good vertical action which will submerge floating material in the paper stock. Such large diameter impellers require substantial horse power to maintain the desired peripheral speed and at the desired peripheral speed the stock tends to spill over the sides of the tank.

The principal object of this invention is to provide a tank in which good vortical circulation may be maintained by a relatively small diameter impeller, the volume of the tank being large because of its high side wall rather than because of the area of the tank bottom.

Another object of the invention is to provide a deep tank of ovate configuration with a relatively small diameter impeller in one end thereof whereby the other end of the tank contains a large mass of material close enough to the pumping effect of the impeller to be readily affected thereby.

A further obiect of the invention is to provide a pulping apparatus whereby the paper stock material is continually subjected to the action of an impeller by the combined effect of lopsided vortical circulation, centrifugal pumping action and gravity.

Still another object of the invention is to provide an ovate tank with a volute impeller casing in the bottom of one end thereof, a tank floor which inclines downwardly toward the feed orifice of the casing and a relatively short, narrow, steep upwardly, inclined open trough for directing stock from the discharge orifice of the impeller casing to the top of the inclined tank floor.

A still further object of the invention is to provide a pulping tank with a narrow upwardly inclined open trough along one side thereof, close to the discharge orifice of a horizontally disposed, rotating impeller and a downwardly inclined floor occupying substantially the remainder of the tank bottom, thereby eliminating any midfeather and permitting a stream of high velocity to penetrate beneath and alongside anoppositely moving mass of paper stock.

"ice

Other objects and advantages of the invention will be apparent from the claims, the description of the drawings and from the drawings in which FIG. 1 is a plan view of the apparatus of the invention.

FIG. 2 is a side elevation in section on line 2-2 of FIG. 1.

FIG. 3 is a side elevation in section on line 3-3 of FIG. 1.

FIG. 4 is an end elevation in section on line 4-4 of FIG. 1.

FIG. 5 is a view similar to FlG. 1 of a modification and FIG. 6 is a view similar to FIG. 2 of the modification shown in FIG. 5.

FIGS. 1-4 illustrate a preferred embodiment of the invention which includes the tank 26 having a side wall 21 of generally ovate outline with a small parti-circular end 22, a large parti-circular end 23 and a pair of opposite

straight sides

24 and 25.

Occupying nearly all of the area below the small end of tank 20 is the volute impeller casing 26 which extends horizontally and preferably occupies about one-third of the area enclosed by the wall 2 1 of tank 20. Impeller casing 26 has a flat, horizontal bottom plate 27 containing an annular pattern of perforations 28 leading to an annular discharge chamber 29 and a stock outlet 30. A flat horizontal top plate 32, forming a minor, but lowermost, portion of the tank bottom is spaced above plate 27 and provided with a feed orifice 33 for feeding the impeller 34 axially and downwardly. The casing side wall 35 is of volute configuration with the axis of the impeller and the centre of orifice 33 slightly offset from the longitudinal centre line of tank 20 whereby an axial feed, peripheral discharge, centrifugal pump is formed.

A tangential, peripheral, discharge orifice 36 is provided in casing 26, the orifice being open at the top and approximately equal in width to one half the diameter of impeller 34, in order to maintain circulation at relatively high consistencies.

Ascending stock conduit means 37 is provided for directing pulped stock discharged from orifice 36 toward the opposite larger end of tank 2@ and upwardly to a level well above the level of casing 26. Preferably means 37 comprises an upwardly inclined trough 38 extending along the side wall 25 and terminating within the large end of the tank 20 at 39.

As best shown in FIG. 3, trough 38 is entirely below floor level and short, narrow and steep as compared to the remainder of the tank bottom for receiving a high velocity stream of stock directly from the impeller through discharge orifice 36. The discharged stock is thus raised to a level well above the level of the impeller 34, and of impeller casing 26, while the stream is close to the impeller orifice and before it has been substantially slowed by the inertia of the stock.

A tank floor 41 forms the major portion of the area of the bottom of tank 20 and extends laterally from the straight side wall 24 beyond the longitudinal centre line of the tank over to the inner side wall 42 of trough 38. Floor 4-1 commences at 43 well below the rim 44 of tank 2% and at a level well above the level of impeller casing 26. The floor 41 inclines downwardly to merge along the transverse line 45, with the flat top plate 32 of casing 26.

The top plate 32 of casing 26 is cut away at 46 and an inclined plate 47 extends from the bottom plate 27 upwardly to eliminate any vertical face in the path of stock discharge which might cause stapling or accumulations of fibres. Plate 32 is preferably cut away at 48 when it joins the side wall 25. I

The impeller 34 is mounted for rotation in a horizontal plane on a vertical axis and is driven by the shaft 5a,

3 the impeller having vanes 51 for creating a vortex in the mass of material above casing 26 and discharging pulped stock peripherally and tangentially from orifice 36. The drive and the impeller are not new and are fully described in my prior Patents 2,351,492 and 2,557,174.

Preferably the outside diameter of the impeller 34 is about half the length of the outside diameter of the casing 26 or about equal in length to the radius of the small parti-circular end 22 of wall 21. Preferably also, the length of the tank 20 is about two times the maximum diameter of the casing 26 while the height of the wall 21 of tank 20 is at least as great as the maximum diameter of casing 26. V

With reference to the diameter of the impeller, the length of the tank is preferably between two and .four times such diameter and the height of the tank is at least two times such diameter. The width of the tank is about two times such diameter and the total width of the discharge orifices is about equal to one-half such diameter.

In operation the tank 20 is charged with a suitable quantity of water and paper stock material such as old magazines and newspapers, up to the level of the dotted line shown in the drawing. The impeller is then rotated counter clockwise, in the direction of the arrows, thereby forming a substantially vertical, vor'tical circulation which extends from the upper level of the paper stock material downwardly to the impeller 34. The entire small end of tank 20 is vortically affected with floating debris rapidly submerged, moved through feed orifice 33 into contact with impeller 34and thrown outwardly by centrifugal force therefrom while being pulped thereby. An eflluent stream of pulped stock is emitted through discharge opening 36 and guided upwardly along the side 25 or tank 20 to the level of the floor 41 at the large end 23 of tank 20. The discharge stream, in ascending trough 38, applies circulatory force on the mass of material in the large end of the tank from below and from the outside to urge the mass back toward the small end of the tank. The downwardly inclined floor 41 permits gravity to constantly urge the mass toward the vortex and, of course, the pumping action of the impeller also tends to circulate the stock counter clockwise within the tank.

No midfeather, baflie or partition, above the level of the tank bottom, or floor, is required in the apparatus of the invention since all stock tends to flow by gravity toward the feed orifice of the impeller'casing from the far end the tank and the stream discharged up trough 38 makes its own penetration of the mass in the opposite direction until it also tends to flow rearwardly by gravity toward the vortex. I have discovered that by locating the orifice 35, the plate 32 and the inclined plate 47 as shown, there is a tendency of stock dischanged from the impeller to flow laterally across the tank before reaching the far end. I term this capability a hydraulic midfeather inasmuch as it tendsto merge the outgoing stock with the stock returning to the vortex and thereby eliminates any'dead space in the tank.

The complete lopsided vortical circulation throughout the entire tank with no dead, or cleavage area, between the outgoing and the returning stock becomes very noticeable as the consistency increases. It is achieved, by stock which rises from passage 38 while sufiicient flow extends to the end of the tank to maintain circulation.

It should be noted that the top line 43 of floor 41 and the terminal line 39 of trough 33 aregenerally at about the level of the mid height of the vortex created by impeller 34. All material once submerged in the vortex and discharged by the impeller is delivered into the bottom of the mass of stock and tends to remain submerged thereafter as it recirculates into the vertical action at the small end or" the tank;

In the device of this invention there is no tendency for the stock to cascade down into the impeller casing, the inclined floor causing the small end of the tank to be full height at all times. The rotation of the impeller is d at a predetermined speed, which may be about three thousand to six thousand feet per minute tip speed in the embodiment illustrated, which maintains circulation while also maintaining elfective vortical submer ence action. Thus at no time does the impeller run bare of stock because of excessive angular speed or piling up of the stock in the far end of the tank.

In FIGS. 5 and 6 a modification is illustrated wherein an open tank 55 of generally oval outline is provided, the tank 55 being undivided and free of any partitions, bafiles, lobes or midfeathers above the level of the tank bottom, or flgir. The tank 55 includes the parti-

circular end walls

56 and 57 and the straight parallel side walls 58 and 5'9. A volute impeller casing 60, impeller 61, impeller shaft 62 and axial feed orifice 63 are similar to those described above and constitute the vertical ci-rculation and defiberizing means 64 of the embodiment. However, the means 64 is located in the centre or" the bottom of the tank 55, below the level of the tank bottom, or floor rather than below one end thereof. In addition, there are a pair of diametrically opposed

discharge orifices

67 and 68 each facing in the opposite direction and each proximate one of the

straight side walls

58 or 59.

A pair of opposite, open troughs 69 and 70- are provided each leading from one of the orifices 67 or 6% along the

adjacent side wall

58 or 59 and around the

adjacent end Wall

56 or 57 to about the centre thereof. Each

trough

69 or 70 inclines upwardly to deliver the tangential, peripheral discharge of the impeller outwardly to the most remote portions of the tank at a considerably higher level than that of the casing. A pair of

floors

71 and 72 incline outwardly from the

end walls

56 and 57 to the impeller casing to urge the stock inwardly to the vortex created above the feed orifice 63. Each

trough

69 or 70 includes a suitable drain grating 73 or 74 for draining the contents of the tank after defiberization.

In this application I use the term ovate to describe the outline, or plan, of the tank to distinguish from tanks, of circular outline. The tank may be oval as in FIG. 5, or egg shaped as in FIG. 1 and the impeller may be olfset from the longitudinal axis as in FIG. 1 or may be centred on the longitudinal axis as in FIG. 5. I use the term orifice to describe the discharge mouth of the volute impeller casing of the invention since the stock in the tank forms the top of the discharge passage and creates a mouth-like aperture through which material is emitted.

I claim:

1. Apparatus for pulping and defibering paper stock comprising in combination a tank of ovate outline, a horizontal volute impeller casing below the level of the [door of said tank, said casing having an axial feed orifice and at least one peripheral discharge orifice; a rotary impeller vwthin said casing creating a vortex above said feed orifice and discharging material longitudinally of said tank through said discharge orifice, a tank floor inclining downwardly toward the feed orifice of said casing and urging all stock in said tank into the vortex created by said impeller by gravity and relatively steep, short, ascending stock conduit means, below the level of said floor, connecting said discharge orifice with an end of said tank, said means directing the peripheral discharge of said impeller initially upwardly to a level well above the level of said casing and impeller and into the area of said tank most remote from said impeller casing, said tank being free of midfeather structure above said tank 2. A combination as specified in claim 1 wherein said floor extends laterally from one side of said tank nearly to the other side thereof, constituting the'major portion 3. A combination as specified in claim 1 wherein the length of said ovate tank is about four times the diameter of said impeller and the height of the wall of said tank is at least twice the diameter of said impeller.

4. A combination as specified in claim 1 wherein the width of the discharge orifice of said casing is at least one-quarter the diameter of the impeller to assure circulation at consistencies above 5%.

5. A combination as specified in claim 1 wherein said ascending stock conduit means comprises an open trough inclining upwardly from said discharge orifice, along the adjacent side wall of said tank and around a substantial portion of the adjacent end wall of said tank.

6. Apparatus for defibering paper stock comprising an elongated tank having a bottom, and side and end walls of generally ovate outline; vortical circulation and defiberizing means in the centre of the bottom of said tank, including a pair of diametrically opposed discharge orifices each proximate the adjacent side wall of the tank; a pair of upwardly inclined open, relatively steep, narrow troughs, below floor level on each opposite side of said tank, each leading from one of said discharge orifices, along the adjacent side wall to proximate the centre of the adjacent end wall of said tank and a floor in said tank, inclining downwardly from the opposite end walls thereof to said vortical circulation and defiberizing means for urging paper stock delivered by said troughs back into said means.

7. Apparatus for pulping and defiberizing paper stock comprising in combination a tank having an upstanding wall of generally ovate outline with opposite, particircular ends, and a pair of opposite straight sides between said ends; a horizontal impeller casing extending between the straight sides of said tank below the level of the tank bottom, said casing having a top plate with a constricted feed orifice therein and having a side wall of volute configuration with at least one discharge orifice therein proximate one side wall of said tank; an impeller mounted for rotation in a horizontal plane on a vertical axiswithin said casing said impeller being adapted to create a vortex thereabove while discharging stock peripherally at substantial speed through said discharge orifice, along the side wall adjacent thereto and toward the particircular end wall in the path of said stock; a wide tank floor inclining downwardly from the wall of said tank to the top plate of said impeller casing, and a narrow trough inclining upwardly from the level of said discharge orifice to floor level well above the level of said feed orifice, the eliluent discharge up said trough constituting a hydraulic midfeather and said tank being free of midfeathers, baffles or partition above the level of the tank bottom.

8. In apparatus for defibering paper stock of the type having an elongated tank with an impeller rotatable on a vertical axis in a volute impeller casing below the level of the bottom of the tank, said casing having a horizontal top plate, with an axial feed orifice, forming the lowermost level of the tank bottom and having a peripheral discharge orifice below said lowermost level, the combination of a discharge trough upwardly inclined from the level of said discharge orifice, along one side of said tank to proximate an end of said tank and terminating at tank floor level and atank floor, entirely above the level of said casing, said floor inclining upwardly from the level of the top plate of said casing tothe wall of said tank, said tank being free of midfeathers, partitions or baffies above the level of said tank floor.

9. Apparatus for pulping and defibering paper stock comprising an elongated tank having a bottom, a pair of opposite elongated side walls and a pair of opposite curved end walls; a horizontally disposed, volute impeller casing extending between said opposite side walls, said casing having a horizontal top plate, with a central feed orifice, forming the lowermost portion of said tank bottom, an impeller mounted for rotation on a vertical axis within said casing below said feed orifice :and at least one discharge orifice, below said top plate, for directing effluent material peripherally and tangentially out of said casing, along .a side wall toward an end wall of said tank; a tank floor inclining upwardly at a predetermined angle from said top plate to the said end wall toward which said efiluent material is so directed, said floor constitnting the remainder of said tank bottom, and a trough extending from said discharge orifice along said side wall to the vicinity of the end wall toward which said effluent material is directed, said trourgh being entirely below the level of said tank floor and inclining upwardly, at a greater angle than the angle of said floor, from discharge orifice level to well above said casing, at floor level.

References Cited in the file of this patent UNITED STATES PATENTS 2,139,430 Witham Dec. 6, 1938 2,557,174 Cowles l June 19, 1951 2,641,971 Ellis June 16, 1953 2,658,426 Cowles Nov. 10, 1953 2,703,533 Cowles Mar. 8, 1955 2,707,420 Skardal et al. May 3, 1955 2,719,462 Fowler Oct. 4, 1955 FOREIGN PATENTS Q 191,025 Switzerland Aug. 2, 19 37