US2999650A - Pulper - Google Patents

Description

Sept. 12, 1961 L. CAMPAGNANO PULPER 3 Sheets-Sheet 1 Filed Nov. 22, 1957 Sept. 12, 1961 L. CAMPAGNANO PULPER 3 Sheets-Sheet 2 Filed Nov. 22, 1957 //VVE TOR BY/ QW,W*M

ATTORNEYS p 1961 L. CAMPAGNANO 2,999,650

PULPEIR Filed Nov. 22, 1957 3 Sheets-Sheet 3 //VVE/VTOR BY f miw PM ATTORNEYS 2,999,650 PULPER Leo Campagnano, Via Borromei 1 B/7, Milan, Italy Filed Nov. 22, 1957, Ser. No. 698,166 6 Claims. (Cl. 24146) This invention relates to an improved and simplified apparatus for the disintegration, separation and pulping of fibrous materials. More particularly, this invention is concerned with the preparation of paper stock from wood, straw, paper machine broke, and other materials used in the paper industry.

An object of my invention is to accomplish pulping with a minimum of absorbed horsepower input for a given production requirement. Another object of my invention is to facilitate sustained continuous operation with an absolute minimum of maintenance requirements. A further object of my invention is to provide apparatus which is basically simple, thereby lowering the expense of initial investment. Still another object of my invention is to provide apparatus which allows ready adaptation for specific pulping applications. Another object of my invention is to permit the pulping of a wide variety of various materials without requiring major alterations in the apparatus. A further object of my invention is to provide a pulper which may also be employed to store paper stock.

In the accomplishment of these and other objects of my invention in a preferred embodiment thereof, I employ a large elongated tub with rounded ends, divided into two channels by an upstanding midfeather. At one end, there is a generally cylindrical pulping section formed by the rounded end of the tub and separated from one side of the midfeather by a screen but communicating freely with the channel on the other side of the midfeather. At the other end of the tub from the pulping section a circulation propeller is so mounted as to produce general circulation of stock around the midfeather through the pulping vat, and back through the screen.

A feature of my invention relates to the use of a rotor at the bottom of the cylindrical pulping area. This rotor is mounted on a vertical shaft extending through the bottom of the tub and is provided with two different kinds of blades which create two substantially separate, distinguishable vortexes, or in another sense, cause two separate paths of stock circulation, one radially outwardly along the bottom of the tub, and the other upwardly and more parallel to the axis of the cylider. These two separate paths of circulation, together with the general circulation caused by the circulating propeller, tend to separate the stock with the more refined particles moving eventually into the outer radial flow path and out through the screen into the general circulation. In this way the more finely subdivided components of the stock are permitted to hydrate under milder conditions of agitation while the larger less dense components remain in the pulping area to be disintegrated.

Another feature of my invention is that the disintegrating action in the pulping area is not only attributable to the mechanical friction of material passing over the blades, but to the division of stock circulation paths. This materially assists pulping by increasing hydraulic frictions.

An additional feature is that the continuous flow of stock around the midfeather and through the pulping area assists the separation of pulped fibers causing them to pass more into the outer circulatory stock path caused by the pulper blades, while the larger pieces of stock yet to be defibered tend to remain in the shorter vertical path where they repeatedly return to-the rotor blades. This results in a faster recycling of the material which need further disintegration. I

Still another feature of my invention the use of a 2 highly simplified purely cylindrical pulping vat configuration requiring no deflectors or other odd shapes, and permitting the bottom of the vat to be flat.

Yet another feature of my invention is the use of a circulation vat attached to and in communication with a pulping vat. As soon as the pulp in the pulper has been reduced to a given dimension, it can flow into the general circulation through the screen connecting the pulper to the circulating section. The pulp in general circulation is thus given a chance to absorb more water and is consequently more easily disintegrated when the general circulation brings it back into the pulping section of the tub. A feature of this arrangement is that the circulating sector can be of greater capacity and may eliminate the need of another vat after the pulper. Still another feature is the use of the circulation vat for pulp storage and/ or the loading of paper machine broke since the simplicity of the vat permits inexpensive construction of large tubs or vats.

An additional feature of my invention is the ready adaptability of the circulation section for eliminating impurities. The low velocity of the circulating stock permits foreign matter to settle at the bottom of the circulating section where it may be easily screened out.

Further objects and features of my invention will best be understood and appreciated from a detailed description of a preferred embodiment thereof, selected for purposes of illustration and shown in the accompanying drawings in which:

FIG. 1 is a cross sectional view in side elevation of the pulper of my invention;

FIG. 2 is a plan view thereof;

FIG. 3 is a cross sectional view in end elevation taken along the line 3--3 of FIG. 1;

FIG. 4 is a partial plan View of the rotor;

FIG. 5 is a cross sectional view of the rotor taken along the lines 55 of FIG. 4;

FIG. 6 is a cross sectional view of the rotor taken along the lines 66 of FIG. 4;

FIG. 7 is a cross sectional view of the rotor taken along the lines 7-7 of FIG. 4;

FIG. 8 is a cross sectional view of the rotor taken along the lines 8-8 of FIG. 4;

FIG. 9 is a view in side elevation of the rotor taken along the lines 99 of FIG. 4;

FIG. 10 is a cross sectional view taken along the lines 1010 of FIG. 4; and

FIG. 11 is a schematic drawing of the pulping vat showing stock flow paths caused by the rotor of my invention.

Referring to the drawings, my invention includes in its general organization an elongated oval tub 10 having rounded ends 12 and 14. An upstanding midfeather l6 partially divides the tub 10 into two channels 18 and 20.

The tub 10 is filled with water and the material to be pulped is introduced into a pulping section indicated at 22 at one end of the tub 10. The pulping section 22 is cylindrical in configuration and is separated from the rest of the tub by a screen 24 on one side of the midfeather 16, but communicates freely with the tub 10 on the other side of the midfeather 16. At the bottom of the pulping section 22, I provide a rotor 26 mounted on a shaft '36 rotating in suitable bearings in the bottom 28 of the pulper section 22. The rotor 26 in this preferred embodiment of my invention is driven by a motor (not shown) and belt 32 attached to a pulley 34 which is keyed to the rotor shaft 36.

Water, or any other desired fluid, is continuously supplied to the tub 10 by means of piping 38, having one inlet 40 controlled by a valve 42 directly above the rotor 26, and another inlet 44 controlled by valve 46 at the periphery of the pulping vat 22. Either or both inlets may be utilized to supply liquid and stock to the tub depending upon requirements.

As the raw material is introduced into the pulping section 22, it is brought into the churning currents caused by the rotation of rotor 26 at the bottom of the'pulping vat. In this preferred embodiment the rotor 26, as shown in detail in FIGS. 4-10, carries two different sets of blades 48 and '50 alternately spaced around a'hub '52 mounted on the drive shaft 36 at 54. The basic shapeof the blades 48 is that of an isosceles triangle diminishing in cross section toward the tip of the blade. The leading edge 56 of the blade 48 is the base of the isoceles triangle describing a convex are as it projects from the hub 52. The trailing edge 60 is pointed and is formed between the two sides 62 of thegenerally isosceles cross section where they meet at the rear (see FIG. 1.0).

Each of the blades 50 has a built up lug 64 cast integrally with hub 52 which is then reduced as shown at 66 (see FIG. 6). The cross section of the blade 50 in the area indicated at 67 (see FIG. .8) is generally rectangular with the width of the blades increasing toward the tip. The leading edge 68 is convex and the trailing edge 70 is concave. The blade terminates with a spoonshaped tip 72 which extends upwardly astindicated at 74, the outer edge being provided with ribs76 to increase friction on the stock.

The shape of blades 48 is similar to those of a centrifugal compressor and causes motion of stock as indicated by the flow lines 78 in FIG. 11 along the bottom of the vat, thence deflected upwards along the sides. The concavity of blades 50 creates a second, coaxial but narrower vortex with a more generally vertical flow path as shown by flow lines80 in FIG. 11 keeping stock in the most vigorously agitated area. Theportion of stock which comes in contact with the blades 50 is subject to a faster and more intense treatment because of the shorter flow path, the more violent change of direction, and the action of the grooves 76. The two different flow patterns are of different velocities thereby creating an action of hydraulic shear which for a givenpower input accomplishes a significantlygreater amount of pulping than in conventional pulpers.

During these operations the material which requires frther pulping is separated from the more finely disintegrated material because the latter tends to be more influenced by the centrifugal action-ofblades t48throwing it out into the vat away from the rotor 26. The coarser material requiring additional pulping tendsrather to follow the shorter vertical cycle 80. The morepulped particles thrown toward the periphery of the pulping section 22 are fiushed'out of the pulping area (if small enough) through the screen 24 and into the. general circulation in tub It). This general stock flow or circulation is actuated by a propeller 84 which is mounted on horizontal shaft extending through the end'wall 14 of the tub It) and being supportedtthereinby suitable bearings. Flow is assured by confining the propeller within a properly dimensioned aperture in a .crosswall 86 and through which the propeller 84 impels the stock. The shaft $7 is driven by a 'belt 92 and motor 94. The continuous flushing of the pulping section '22 of stock components which are small enough to passthrough the screen 24 permits the rotor '26 to act mainly upon material requiring additional pulping. This 'both increases the efiiciency of pulping and"prevents'over-pulping.

'Theparticles carriedintothe general-circulation are further exposed to hydration and agitated, enhancing the pulping effects of the pulping vat which reduces the power required'to pulp a given quantity of material. This same relatively slow movement-of stock through the'pulping area "22 and "aronnd-the -midfeather 16 in the general circlating section "permits ready removal of foreign matter which'tends to settle at-the bottom,-by placing -a screen 96 near tub end-14.

'Itis a particular feature 'of'my inventionz'that the screen 24 does not become clogged with over-sized particles. is due "to two things. First, the dual flow pattern of the stock in the pulper section 22 tends to separate the larger components of the stock and return them toward the center. Second, the stock is swirling tangentially in the pulper section '22 with much greater velocity than mill is flowing through the screen 24. This causes thelargerparticlesto break away from the screen and return to theipulpingzflowpaths.

Particles of stock brought back into the pulping section '22 by the general circulation, if sutficiently pulped, are removed through a discharge outlet 98 located in the metal plate 28-near the-rotor 26. A discharge pump 100 and valve 102 control outflow-through the pipe 104. A downstream line oil the pump empties into a storage vat for pulped material neither of which are shown in the drawings. There is also a by-pass system indicated at 106 for returning stock to the pulper for further pulpmg.

Since numerous minor variations of this preferred embodiment of my invention will now be apparent to those skilled in the art, it is not my intention to confine the invention to the precise form herein shown, but rather to limit it in terms of the appended claims.

Having .thus described and disclosed a preferred embodiment of my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. Pulping apparatus for paper stock comprising a tub, a section of said'tub set aside for pulping but in communication with the remaining portions of said tub, means in said pulping section for subjecting paper stock to a vigorous hydraulic sheer pulping action including a pulping rotor having first blades thereon for directing said stock outwardly and second blades thereon for directing said stock upwardly, and separate means for continuously withdrawing from said pulping section and circulating around said tub under conditions of comparatively mild agitation stock components of a predetermined maximum particlesize.

2. -A pulper comprising a generally oblong tub with bottom,tsides and ends, divided longitudinally by an upstanding midfeather, means for imparting general circulation .of-stock around said midfeather, pulping means at .a pulping end of said tub for imparting a dual flow path to said stock one said path being radially outward from said means and the other said path being more nearly vertical, a substantially vertical screen isolating said pulping means from said tub on the side of said midfeathert at the output of said general circulation from said pulping stock,.and a discharge outlet for pulped stock at the bottom of said tub.

3. A pulper comprising a tub including a bottom, sides and ends, an upstanding midfeather mounted on the said bottom clear of the said ends, a generally arcuate vertical screen connecting one end of said midfeather to one of said sides, a cross-wall between the other end of said midfeather and the other of said sides, said cross-wall being perforated to form an opening for passage of stock, a shaft coaxial with said opening, a propeller mounted fast on said shaft to rotate therewith, means for rotating said shaft causing a general circulation around said midfeather in a rotational direction flowing through said screenout of said end bounded thereby, and pulping means in said tub on the discharge side of said propeller said means imparting two substantially separate flow paths comprisingtan outer vortex and an inner vortex, said outer vortex having the same rotational direction and coinciding ingpart with said general circulation.

4. A pulper comprising a tub including a bottom, sides and ends, an. upstanding midfeather mounted on the bottom..,clear of the vends, a generally vertical screen connecting one end ofsaid midfeather to one of said sides, a vertical shaft through the bottom of said tub between the screen end of said midfeather and the tub end, a .rotorwithra firstisetaand second setof blades mounted fast to said shaft to rotate therewith, said first blades constructed to promote a stock flow path generally outwardly from said rotor, said second blades constructed to promote a more vertical stock flow path, means for continually flushing stock in the flow path created by said first blades out of said path through said screen and around said midfeather a discharge outlet for stock at the bottom of said tub.

5. A pulper comprising an elongated tub with bottom, sides and ends, a pulping section and a circlating section in said tub, an upstanding midfeather dividing said circulating section longitudinally, means for creating general stock circulation around said midfeather and through said pulping section, said pulping section separated from said circulating section by a screen, pulping means in said pulping section including a rotor, first and second blades on said rotor, said second blades adapted to cause a generally vertical stock current path, said first blades adapted to cause a generally radial stock current path in said pulping section in the same rotation direction as the general circulation, and a discharge outlet for said tub.

6. In a pulper, a vat, a rotor, means for rotating said rotor in said vat in contact with paper stock, first blades on said rotor presenting a substantially vertical surface 6 to said stock for driving said stock in an outward radial path, and second blades on said rotor presenting an upwardly slanting surface to said stock for driving said stock in a more vertical path, whereby the smaller and more disintegrated components of said stock are directed in a path radially outward from said rotor then upwardly and around said vat; means operatively associated with said rotor for directing the larger and less disintegrated components of said stock in a more vertical and shorter circulatory path upwardly from and returning to said rotor; and means for continuously withdrawing stock components smaller than a certain maximum size from said radial path out of said vat.

References Cited in the file of this patent UNITED STATES PATENTS 1,692,602 Witham Nov. 20, 1928 1,768,735 Beers July 1, 1930 1,811,741 Bishop June 23, 1931 2,424,726 Wells July 29, 1947 2,434,449 Wells Jan. 13, 1948 2,719,462 Fowler Oct. 4, 1955 2,902,228 Higer Sept. 1, 1959 2,911,334- Stuck Nov. 3, 1959

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