US2681598A - Paper machinery - Google Patents

Description

June 22, 1954 J. BAXTER, JR 2,681,598

PAPER MACHINERY Filed June 4, 1951 2 Sheets-Sheet 2 INVENTOR. JOSEPH Bnxran ,Jz.

A TTORNE Y5 Patented June 22, 1954 PAPER MACHINERY Joseph Baxter, Jr., Franklin, Ohio, assignor to The Black-Clawson Company, Hamilton, Ohio, a corporation of Ohio Application June 4, 1951, Serial No. 229,810

7 Claims.

This invention relates to pulping apparatus for liquid slurry stocks such as paper making stock, and more particularly to a rotor or impeller for such pulping apparatus.

The invention has special relation to an impeller for pulping apparatus which will be par ticularly effective for use in defibering pulp for paper making stock, and one of the principal objects of the invention is to provide such an impeller which will have so effective an abrading action on the particles and lumps of pulp as to accomplish substantially complete defibering at economical cost in terms of the requirements of both power and operating time.

This general object is accomplished in accordance with the invention by means of an impeller for this purpose which incorporates bowl-shaped working surface portions having abrasive areas thereon and arranged for rotation about an axis such that centrifugal force will tend to force the pulp into abrading contact with these surface areas. However, since in such abrading action, there is a tendency upon prolonged engagement between the work material and the abrasive surface for the material to load or coat the abrasive and thus to reduce its effectiveness, in the impellers of the invention, the abrasive surface areas are arranged in discontinuous relation such that the interval of working engagement between any given area and a single lump or part cle of work material is effectively limited to prevent such loading or coating action, and the lumps and particles are frequently upset to present a fresh surface to the Working faces of the impeller.

It is therefore an object of the invention to provide an impeller for pulping or defibering apparatus which includes multiple abrasive surfaces arranged in discontinuous relation such that they act successively on the particles of pulp passing across the impeller under the influence of centrifugal force and which also is of such construction and arrangement that the particles of pulp tend to be upset in passing from surface to surface in such manner as to present fresh areas to successive abrasive surfaces and thereby to prevent loading or coating of the abrasive.

Another object of the invention is to provide an impeller for a pulping or defibering apparatus having thereon multiple working surfaces arranged in concentric relation about the rotational axis of the impeller and inclined toward this axis to cause the particles of pulp to be urged into rubbing engagement with the working surfaces by the centrifugal force generated by rotation of the impeller, and more particularly to provide such an impeller wherein successive working faces are arranged in axially offset and overlapping rela-- tion such that the outer periphery of each Working face forms a working edge for upsetting the particles of pulp passing radially outwardly thereacross.

An additional object is to provide such an impeller having concentric working faces thereon wherein the successive faces are spherically curved on substantially the same radius of curvature and with the centers of curvature thereof located on the rotational axis of the impeller but in progressively ifferently spaced relation with the central plane of the impeller such that successive working faces are in diiierently inclined relation with the axis of the impeller While at the same time providing a large total effective working area on the impeller within relatively confined axial dimensions.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings Fig. l is a View partly in side elevation and partly in vertical section showing a pulping apparatus embodying an impeller constructed in accordance with the invention;

Fig. 2 is a plan view of the impeller;

Fig. 3 is a section on the line 33 of Fig. 2;

Fig. 4 is a detail sectional view illustrat ng an intermediate step in the construction of the impeller;

Fig. 5 is an enlarged and somewhat diagrammatic fragmentary view in section illustrating the operation of the impeller;

Fig. 6 is a view partly in side elevation and partly broken away in vertical section showing another form of pulping or delibering apparatus embodying multiple impellers constructed in accordance with the invention;

Fig. '7 is a section on the line T- i of Fig. 8;

Fig. 8 is a partial view of the face of one of the impellers of Fig. 6, the view being partly in elevation and partly broken away;

Fig. 9 is a section on the line 9-9 of Fig. 8; and

Fig. 10 is an enlarged fragmentary section illustrating diagrammatically the operation of the impeller of Figs. 6 to 9.

Referring to the drawings, which illustrate preferred embodiments of the invention, Fig. 1 shows a pulping apparatus generally of the construction disclosed in Martindale Patent 2,371,837, issued March 20, 1945, to the assignee of this application. This pulper includes a tub or vat having a cylindrically extending upper wall portion it, an inwardly tapered lower wall portion i l and a bottom wall [5, and it is carried by supports l6 of any suitable character. Arranged below the tub is a drive such as a pulley ll adapted for connection to a motor, not shown, and connected through a suitable gear transmission mechanism indicated at l8 to a rotatable shaft which extends up through an opening in the bottom l of the tub and carries a rotatable pulping impeller 2!] arranged adjacent the bottom of the tub and above its bottom wall.- The rapid rotation of the impeller 2i! provides an effective circulation outwardly and then upwardly along the outer portions of the tube with a return down flow towards the impeller, as indicated by the arrows, and vanes or plates H are mounted on the wall portion Hi to guide the upward flow of the pulp or stock. Adjacent the bottom of the tub is an annular chamber or compartment 22 partitioned from the space above the impeller by a perforate extractor plate 25 of frusto-conical form which permits the passage of the fine pulp to the compartment 22, from which it may be withdrawn as desired by way of the conduit 26 shown as provided with a shutofi valve 2?.

The impeller 2t includes a main plate or disk 30 having a shaft portion 3! for connection to the drive for rotation as described about its central axis 32. On the upper surface of the plate 38 are a plurality of annular working faces 33 arranged in concentric relation about the rotational axis 32 of the plate. Six of these working faces are shown, being identified individually as 33a to 331, and they are inclined towards the axis 32 so that in combination they form a series of concentric troughs on the surface of plate 33. In addition, a plurality of curved vanes 35 are mounted near the center of plate 33 to serve as pumping vanes urging the pulp radially outwardly across the surface of the plate as the impeller rotates in operation.

The working faces 33 are arranged on the impeller as shown with each extending further in an axial direction above the surface and central plane of plate 36 than the adjacent working face on the inner side thereof, so that each face tends to intercept directly a portion of the stock discharged radially from the working faces between itself and the center of the impeller. Also, while the several working faces 33 may be formed in frusto-conical shape, it is advantageous to form them as portions of a sphere, and particularly portions of the same spherical surface since this has the further effect of causing each individual working face to incline at a greater angle to the axis 32 of the impeller than the next face on the inner side thereof.

The impeller 26 may be formed as an integral casting including the working faces 33, or it may be fabricated as illustrated in detail in Figs. 3 to 5. Initially the several working faces 33 comprise integral portions of a bowl-shaped member indicated generally at 38 in Fig. 4, which is subdivided to form a plurality of concentric rings it, and these rings are mounted on the plate 39 with their upper surfaces forming the working faces 33. As shown, the rings dfia to 40 are secured together by welding and are secured to the plate 30 by means of bolts 41 and spacers 42 and 13, with the bores for the heads of bolts d9 being filled in at M by lead In addition each of 4 the rings 33 is provided on its upper surface with an abrasive coating 45, such for example as a sputtered coating of tube boron or the like.

In mounting the several rings 33 on plate 39, their upper suriaces are maintained parallel with their original surface of curvature, represented by the line it in Fig. 3, thus imparting an essentially bowl-like shape to the finished impeller in that all of the working surfaces are spherically curved about the same radius of curvature, but with the centers of curvature of the several rings being located in differently spaced relation along the axis 32, the center of the inner ring 33a being located furthest from the plate and the center of curvature of the ring 33; being nearest the plate. Thus the total effective working surface of the several rings remains equal to that of the annular portion of the bowl 38 from which each were cut, but they will be compressed into a substantially smaller space measured axially of the plate.

Fig. 5 illustrates diagrammatically the operation of the impeller in a pulping apparatus of the type shown in Fig. 1. With the working faces 33 constructed and arranged as described, each of these working faces has its outer rim 5c located in axially overlapping relation with the adjacent working face 33 to provide a working edge 5i at the outer periphery of each working face, which has important functions in the operation of the device. As noted, continuous abrading engagement between working material and an abrasive surface frequently tends to load or coat the abrasive by filling the interstices between the abrasive particles until their abrading action is substantially neutralized. Such an effect would tend to result if the entire bowl member 33 were mounted as a unit on the plate 35 to provide a single radially continuous abrasive surface, and in addition, the use of such a bowl would tend to discharge the stock from its periphery at too step an angle for effective removal through the extractor plate 25.

The constructionof the present invention, with its multiple discontinuous and relatively offset abrasive working surfaces, prevents both of these undesirable results and provides highly eifective and efficient defibering at economical cost in terms of both power and time. In operation, the centrifugal force generated by rotation of the impeller, which is supplemented by the action of the pumping vanes 35, causes continuous radially outward flow of stock across the faces 33 and at the same time tends to force the particles of pulp into abrading engagement with the abrasive coating on the working faces. However, each individual working face is of relatively short radial dimensions, for example, from four to six inches in an impeller having a total diameter of the order of ninety inches, and at the periphery of each working face, the particles of pulp must 7 cross a working edge 5! before reaching the next abrasive surface.

As illustrated by the arrows in Fig. 5, the over lapping contruction of the working faces creates suction in the direction of the bcttom of each of the troughs formed by adjacent rings it, and since at the same time the natural tendency of the centrifugal force is to throw the stock off in a generally upward direction, considerable turbulence will develop in each trough which will have the desirable effect of tumbling the individual particles of pulp around so that when they again come in contact with an abrasive surface, they will present a fresh surface to the abrasive.

In addition, the downward suction just beyond each working face will tend to have the effect of drawing the particles or bundles of fibers around the working edges 5i for additional defibering action.

The general action of this impeller, as already noted, is to create an effective circulation radially outwardly from its rotational axis and then upwardly along the outer portions of the tub with a return flow downwards in the central part of the tub. Thus the pulp is caused to flow repeatedly in radial directions outwardly along the surface of the impeller, and on each pass thereacross, a given particle or bundle of fibers is subjected to repeated abrading action interrupted by scraping across the edges 5| and tumbling into the troughs between working faces. These several working actions, including the hydraulic action of the turbulent currents and eddies in the troughs, provide highly effective and efficient defibering at economical cost in terms of both power and time, and in addition the discharge of stock at the periphery of the impeller is maintained at desired low angles for proper removal of the separated fibers through the extractor plate 25.

Figs. 6 to show another type of pulping or defibering apparatus which incorporates multiple impellers in accordance with the invention and includes an outer shell til having an inlet 6! and a generally volute outlet 62. A motor 85 drives a shaft 65 which extends through the shell 68 and carries a breaker impeller 6? at the inlet end and a pumping impeller 68 at the discharge end of the shell. Within the shell 58 is a twopiece liner or inner shell 18 of nonuniform shape formed internally in cross-section with alternat ing cylindrical and elliptical portions, and with adjacent elliptical portions having their long axes at right angles. Thus as shown in Figs. 6 and '7, each cylindrical portion H has an elliptical portion '52 arranged on one side thereof with its long axis horizontal and on the other side is an elliptical portion i3 having its long axis vertical.

The shaft 66 carries a plurality of impellers 15, one being located within each of the elliptical portions of the inner shell. Each impeller is formed as shown in Figs. 8 and 9 of a pair of semi-cylindrical plates ll secured together by screws 18 in clamped relation on shaft S6, and each plate 1'! has on both sides thereof multiple discontinuous concentric working faces 89 which may be fabricated as described in connection with Figs. 3 to 5 or may be cast integrally as shown. Since the impellers are of relatively small diameter, for example about 12 inches, these impellers each include a smaller number of working faces than the large diameter rotor shown in Figs. 1 to 5, four of these faces being shown and identified as 86a to 80d.

The working faces 83 are arranged in the same inclined relation with each other and the axis of shaft as as described in connection with the impeller 2s. Each face 86 is shown as parallel with a portion of the spherical surface repre sented by the dotted line 8! which passes through approximately the center of the impeller 15, and the several faces are arranged with their inner edges approximately in a common plane normal to shaft 85 so that each face is inclined at a greater angle to the shaft and extends axially further than the adjacent face on its inner edge. Each face is also provided with a coating of adhesive 85 as described in connection with Fig. 5.

In operation, the working surface on each side of each impeller has essentially the same action on the pulp as described in connection with Fig. 1, with the individual particles or bundles being abraded across each working face and then tumbled over the edge 88 to the next face. Additional desired conditions of turbulence are set up by the arrangement of impellers as shown such that each has a tendency to discharge stock in a curving path towards the discharge from the opposed working surface of the adjacent impeller, and in addition the arrangement of alternating cylindrical and elliptical passages through the inner shell of the device forces an irregular path on the stock and introduces necessary angular movements of the stock flow which further promotes turbulence and high hydraulic shearing forces which supplement the abrasive action of the impellers in producing quick and efficient deflbering.

While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that chan es may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. An impeller adapted for use in defibering paper making stock in apparatus of the character described including a chamber adapted to contain a quantity of said stock for refining, comprising a plate adapted for rotation in said chamher about an axis substantially normal to said plate to subject said stock to centrifugal force causing said stock to circulate radially across the surface of said plate, means forming a plurality of separate annular working faces arranged on a surface of said plate in radially spaced relation with each other and in radially spaced relation with said axis, the outer periphery of each said annular working face being not greater than the inner periphery of the next outer said working face each said working face being of substantial radial dimensions and being inclined outwardly with respect to said axis to cause particles in said radially circulating stock to be forced into working engagement with said faces by the action of centrifugal force, and each said working face having the outer rim thereof arranged in axially overlapping relation with the inner rim of the next outer said working face to form a working edge intermediate adjacent said working faces for changing the path of movement of said stock passing thereacross.

2. An impeller adapted for use in defibering paper making stock in apparatus of the character described including a chamber adapted to contain a quantity of said stock for refining, comprising a plate adapted for rotation in said chamber about an axis substantially normal to said plate to subject said stock to centrifugal force causing said stock to circulate radially across the surface of said plate, means forming a plurality of separate annular working forces arranged on a surface of said plate in radially spaced relation with each other and in radially spaced relation with said axis, means forming an abrasive surface on each of said working faces for abrasive action on said stock, the outer periphery of each said annular working face being not greater than the inner periphery of the next outer said working face each said face being of substantial radial dimensions and being inclined outwardly with respect to said. axis 7.. to cause particles in said radially circulating stock to be forced into abrading engagement with said abrasive surface by the action of centrifugal force, and each said working face having the outer rim thereof located. in axially overlapping relation with the inner rim of the next outer said working face to form a. working edge intermediate adjacent said abrasive surfaces for upsetting the path of the particles and bundles of fibers in said stock passing thereacross to cause different surfaoeareas of said particles and bundles of fibers to engage successive said abrasive surfaces.

3. An impeller adapted for use in defibering paper making stock in apparatus of the character described including a chamber adapted to contain a quantity of said stock for refining, comprising a plate adapted for rotation of said chamber about an axis substantially normal to said plate to subject said stock to centrifugal force causing said stock to circulate radially across the surface of said plate, means forming on a surface of said plate a plurality of annular troughs concentric about said axis and each having an inner wall and an outer Wall, the outer wall of each said trough being inclined away from and facing the inner wall of said trough to form an annular working face, means forming an abrasive surface on each said working face, the

outer periphery of each said annular working face being not greater than the inner periphery of the next outer said working face each said working face being of substantial radial dimensionsto cause particles and bundles of fibers in said radially circulating stock to be forced into abrading engagement with said abrasive surface by the action of centrifugal force, and each said inner wall and the outer wall of the adjacent said trough intersecting to form a working edge for causing. said stock to flow from trough to trough in an irregular path and causing different surface areas of the particles and bundles of fibers in said stock to engage successive said abrasive surfaces.

4. An impeller adapted for use in defibering paper making stock in apparatus of the character described including a chamber adapted to contain a qantity of said stock for refining, comprising a plate adapted for rotation in said chamber about an axis substantially normal to said plate to subject said stock to centrifugal force causing said stock to circulate radially across the surface of said plate, means forming a plurality of separate annular working faces arranged on a surface of said plate in radially spaced relation with each other and in radially spaced relation with said axis, the outer periphery of each said annular working face being not greater than the inner periphery of the next outer said working face each said Working face having the outer rim thereof arranged in axially overlapping relation with the inner rim of the next outer said working face to form a working edge intermediate, adjacent said working faces for changing the path of movement of said stock passing thereacross, each said working face being of substantial radial dimensions and being inclined outwardly with respect to said axis to 5. An impeller adapted for use in defibering paper making stock in apparatus of the character described including a chamber adapted to contain a quantity of said stock for refining, comprising a plate adapted for rotation in said chamber about an axis substantially normal to said plate to subject said stock to centrifugal force causing said stock to circulate radially across the surface of said plate, means forming a plurality of separate annular working faces arranged on a surface of said plate in radially spaced relation with each other and in radially spaced relation with said axis, the outer periphery of each said annular working face being not greater than the inner periphery of the next outer said working face, each said working face having the outer rim thereof arranged in axially overlapping relation with the inner rim of the next outer said working face to form a working edge intermediate adjacent said working faces for changing the path of movement of said stock passing thereacross, each said working face being of substantial radial dimensions and being inclined outwardly with respect to said axis to cause particles in said radially circulating stock to be forced into working engagement with said faces by the action of centrifugal force, each said working face being inclined at a greater angle with respect to said axis than the adjacent said face located radially outwardly thereof, and each said working face extending further in an axial direction from said surface of said plate than the adjacent said face located radially inwardly thereof.

5. An impeller adapted for use in defibering paper making stock in apparatus of the character described including a chamber adapted to contain a quantity of said stock'for refining, comprising a plate adapted for rotation in said chamber about an axis substantially normal to said plate to subject said stock to centrifugal force causing said stock to circulate radially across the surface of said plate, means forming on a surface of said plate a plurality of annular troughs concentric about said axis and each having an inner wall and an outer wall, the outer wall of each said trough being inclined away from and facing the inner wall of said trough to form an annular working face, means forming an abrasive surface on each said working face, the outer periphery of each said annular working face being not greater than the inner periphery of the next outer said working face each said working face being of substantial radial dimensions to cause the particles and bundles of fibers in said stock to be forced into abrading engagement with said abrasive surface by the action of centrifugal force, each said inner wall and the outer wall of the next inner said trough intersecting to form a working edge for causing said stock to flow from trough to trough in an irregular path and causing different surface areas of the particles and bundles of fibers in said stock to engage successive said abrasive surface, said working faces being spherically curved about substantially the same radius of curvature, and each said working face having the center of curvature thereof located on said axis and nearer to said surface of said plate than the center of curvature of the adjacent said face located radially inwardly thereof.

'7. An impeller adapted for use in defibering contain a quantity of said stock for refining, comprising a plate adapted for rotation in said chamber about an axis substantially normal to said plate to subject said stock to centrifugal force causing said stock to circulate radially across the surface of said plate, means forming on a surface of said plate a plurality of concentric concave annular working faces, said working faces being spehrically curved about substantially the same radius of curvature, each said working face having the center of curvature thereof located on said axis and nearer to the central plane of said plate than the adjacent said face located radially inwardly thereof, the outer periphery of each said annular working face being not greater than the inner periphery of the next outer said working face each said working face being of substantial radial dimensions to cause particles in said radially circulating stock to be forced into working engagement with said faces by the action of centrifugal force, and means forming on each said working face an abrasive surface for abrasive action on the stock flowing radially across said plate surface.

References Cited in the file of this patent UNITED STATES PATENTS Wandel Apr. 8, 1952

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