JPH055959B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an apparatus for pulping or disintegrating high consistency paper pulp raw materials, e.g. 12 to 25% solids; This relates to a pulping device in which a trochanter circulates pulp raw material within a tank.

A pulping apparatus for disintegrating waste paper or the like includes a tub or vat within which is mounted at least one trochanter or impeller for circulating the stock to be disintegrated. The trochanter currently in use disintegrates the stock by creating mechanical and/or hydraulic shear conditions that impart a predetermined particle size to the pulp. Acts to reduce the maximum dimension of. Mechanical shearing typically occurs through the interaction of the moving surface of the trochanter and the stationary surface of the bottom wall or floorboard, to which the trochanter is typically mounted. Hydraulic shear occurs when pulp fibers contact each other within the pulp stock as a result of the turbulence or flow patterns created by the trochanters within the vessel.

BACKGROUND OF THE INVENTION Many pulping equipment currently in use are capable of disintegrating pulp stock to a maximum consistency of about 5 to 8% solids, such as in the pulping equipment described in US Pat. No. 4,109,872. This patent describes a pulping apparatus having a relatively flat body and a plurality of vanes extending generally radially outwardly from the body. As the trochanter rotates, it creates hydraulic pressure and mechanical shear near the trochanter vanes. However, such pulping equipment is not capable of pulping stocks with a consistency higher than about 10% solids, since such high consistency stocks are not capable of pulping in the vat in response to the rotation of the trochanter. This is because it cannot be circulated.

For example, it is desirable to pulp a stock having a high consistency of 12 to 25% solids. Not only can a particular vat hold a larger amount of pulp for a particular batch being processed, but also, when the pulp is properly circulated, the shear created by the higher density pulp can move the stock at a higher rate than the lower density pulp. Can be disassembled. However, pulping equipment of the type described above is not capable of pulping stocks of such high consistency. Since the viscosity of the high-consistency stock is high, when the trochanter rotates, it displaces the pulp material outward from the vicinity of the blades, but the stock above the trochanter does not flow downward, filling the voids and moving the trochanter. This results in a cavitation condition. When such cavitation conditions occur, the pulp stock is not circulated and the desired mechanical and hydraulic shear does not occur.

The trochanter has means for forcing the stock downwardly from the center of the vat and into contact with the pumping member. For example, U.S. Pat. No. 3,035,781 includes a body with a hyperbolic profile supporting a pair of flat screw steps. Each screw step is helical and includes a leading edge oriented generally perpendicular to the axis of rotation of the trochanter and a trailing edge oriented generally parallel to the axis of rotation. When pulp stock is present and the trochanter rotates, the screw steps push the pulp stock downward and cooperate with the hyperbolically contoured body to pump the stock radially outward, as used in this patent. Consistency of raw materials is not listed.

PROBLEM SOLVED BY THE INVENTION One drawback associated with such a trochanter is that the rear part of the screw step does not interact with a stationary object and therefore does not create mechanical shear conditions that promote disintegration of the pulp stock. . Furthermore, the majority of the screw steps are inclined relative to the axis of rotation, so that the pulp stock tends to be pushed outwardly from the axis of rotation before it reaches the rear pumping section of the screw step. . Since this outwardly flowing pulp stock does not contact the pumping section, the hydraulic shear effect acting on the pulp stock is reduced.

There is therefore a need for a high consistency pulping device that includes a trochanter that can generate both hydraulic and mechanical shear forces. There is also a need for a high consistency pulping apparatus having a trochanter that reliably guides the pulp stock downwardly and engages all working surfaces of the pumping means to maximize hydraulic shear forces.

The present invention can be disintegrated by prior art equipment and typically has a volume of about 12 to 8% solids compared to a low consistency pulp stock of about 5 to 8% solids.
The present invention provides a pulping equipment capable of disintegrating pulp raw materials with a high consistency of 25% solids.

SUMMARY OF THE INVENTION The pulping apparatus of the present invention includes a trochanter adapted to generate both mechanical and hydraulic shear forces thereby maximizing the disintegration rate of high consistency pulp stock. . Another advantage of the present invention is that it pumps a larger portion of the high consistency pulp in the center of the vat downwards and in contact with the pumping surface of the impeller than in prior art devices, thus delivering a larger amount of pulp than previously possible. Pressure against the walls of the tank and circulation outward increases the level of hydraulic shear.

The present invention comprises a tank having a screen portion for removing pulp material having a large amount of material passing through the screen from the tank, and a substantially cylindrical side wall extending upward from the bottom wall, and a tank mounted at the center of the bottom wall so as to rotate about a vertical axis. An apparatus for pulping a high consistency pulp stock including a trochanter including a plurality of radially outwardly extending vanes and a plurality of helical screw steps extending upwardly from a base. It is.

Each screw step had a concave lower surface that pulled the pulp material inward toward the axis of rotation when the trochanter rotated, and the screw step pushed the pulp material downward toward the disintegration surface of the screw blade. It has a shape. Furthermore, each screw step has a convex outer surface that is considerably larger in area than the lower surface and acts like an airfoil to create a suction force that draws the pulp material into the concave surface passage of the next step. .

To be distributed over the entire area of the ablation surface of the trochanter vanes, each helical step of the screw includes a step terminating at the base of the trochanter and having a width in the radial direction approximately equal to the radial dimension of the vane. The pulp material that is pumped downward by the screw step is placed near the base of the trochanter, and as a result of the screw step and the defibration surface of the trochanter blade having the same width, the trochanter blade is defibrated. It is spread over the entire surface.

Before hitting the disintegration surface of the trochanter blade, the pulp raw material, which is pumped downward by the rotating screw step, moves away from the trochanter and disperses outward. This tendency, together with the rear part, forms an approximately thorn-shaped conduit. This is prevented by providing a similar raised ridge at the rear of each screw step extending upwardly from the screw step. These ridges guide the pulp passing over the upper surface of the screw step downwardly toward the disintegrating surface and prevent the pulp stock from dispersing once it is drawn inwardly by the screw step and the concave lower surface.

Preferably, the rear portion of each screw step intersects each one of the trochanter vanes such that the trailing edge of each screw step is coincident with each trochanter vane. When the screw steps and the trochanter blades are arranged in this manner, a gap is formed between the blades and the bottom wall of the tank directly below the trochanter blades is exposed. Tightly spacing the trochanter upwardly from the bottom wall can create a mechanical shear condition between the trochanter vanes, the cistern, and the bottom wall.

In one preferred embodiment of the invention, the boss portion of the trochanter is generally frustoconical, but the sides are curved rather than straight, forming an extension of the conical boss portion of the core of the feed screw. to form a downwardly outwardly opening surface which cooperates with the screw step to direct the pulp outwardly into the passageway of the disintegrating surface of the screw step.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an apparatus for efficiently and economically pulping high-consistency stock and for displacing the pulp stock inwardly so that it can contact the entire disintegrating surface of the trochanter vanes. Apparatus for pulping high consistency pulp stock comprising means for pulling the stock downwardly, thereby minimizing the occurrence of cavitation, and a trochanter such that the stock enters the passageway of the disintegrating surface of the trochanter vane. and a pulping apparatus including means for pumping down to the trochanter vanes to minimize outward flow.

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

The invention will now be described with reference to the accompanying drawings.

EXAMPLE As shown in FIG. 1, one preferred embodiment of the pulping apparatus of the present invention is generally designated 10.
This pulping tank 10 includes a pulping tank shown in
is a bottom wall consisting of a flat central portion 11 surrounded by a frusto-conical extraction plate 12 surrounded by an angularly tapered solid frusto-conical portion 13; and a generally cylindrical side wall 14 extending from the side wall 14 to the cylindrical side wall 14 .

Below the extraction plate 12 there is an annular throughput chamber 15, which has a tapered bottom 16 and an outlet pipe 1 with a prior art control valve (not shown).
7. An additional outlet 18 is provided in the bottom wall 13 to remove material that is too large to pass through the extraction plate 12.

A trochanter, generally designated 20, is centrally mounted to the bottom wall 13 and rotates about a generally vertical axis. Trochanter 20 is, for example, cited in this application.
Preferably, it is driven by an electric motor (not shown) in a manner well known in the art, such as that described in U.S. Pat. No. 4,109,872. The lower surface of the trochanter 20 is frustoconical, corresponding to the frustoconical extractor plate 12, but if the boss is provided with a flat extractor plate as described in U.S. Pat. No. 3,073,535, the trochanter's The bottom also needs to be flat.

The bottom of the trochanter 20 is of substantially the same construction as described in U.S. Pat. No. 4,109,872, except that the trochanter of this patent has six vanes, whereas the trochanter of the present invention has only three vanes. are doing. Figure 2, Figure 3,
As shown in detail in Figures 4 and 8,
The trochanter 20 includes a boss portion 20 which is generally conical in shape but is preferably taped upwardly along a notched curve rather than a straight line. Three vanes 22 extend radially from the boss portion 21, each vane 22 having a cylindrically sloped outer end surface 24 and a flat disintegration surface 25 that slopes forward and has a trailing edge 26.
and a pumping surface 27 which is also straight but curved when viewed in plan.

A feed screw 30 extends upwardly from the trochanter boss portion 21, and this screw 30 forms an upwardly tapered extension of the trochanter boss portion 21 to prevent pulp material from accumulating at the top of the screw. Core portion 31 terminating in a swivel blade 32
Contains. The screw 30 also includes three screw steps 33 that are generally helically intertwined and include a rear portion 35 that merges with the upper surface of each vane 22 of the trochanter. The radial dimension of the screw step 33 increases from the top of the screw 30 toward the boss portion 21 of the trochanter to form a rear portion 35.
increases to balance the increased diameter of core portion 31 such that the width of the terminal edge of vane 22 is approximately equal to the corresponding radial dimension of vane 22 . Screw step part 3
3 is oriented relative to the trochanter 22 such that its terminal edge coincides with the trailing edge 26 of the trochanter vane 22.

The rear portions 35 of the screw steps 33 include raised peripheral edges 40 extending upwardly from their respective outer edges. The outer circumferential ridge 40 includes a rectangular rear end 41, and the tip of this outer circumferential ridge merges with the upper surface of the screw step to prevent fibers from accumulating at this point during the pulping operation and preventing the pulp raw material from proceeding downward. The radially outer surface of the peripheral edge forms a continuation of the pumping surface 27 of the trochanter 20.

As shown in FIGS. 4, 5 and 6, the screw steps 33 are generally arcuate in cross-section and each have a generally concave lower surface 44 giving it a cup-like appearance and function. This tip-like shape extends the entire length of each step 33, and FIG. 7 shows a typical screw step 33 in detail in a side cross-sectional view. The outside or rear side 45 of each step 33
has a smooth convex shape and is considerably longer than the lower surface 44, which forms the leading edge surface, as measured along a radial cross section.

As shown in detail in FIG. 4, the underside of the trochanter 20 is shaped to conform to the contours of the bottom wall and extraction plate 12 of the pulping tank 10 (FIG. 1). The trochanter blade 22 is located directly above the extractor plate 12, and the gap between the trochanter plate and the extractor plate is formed at a location where mechanical shearing action is performed. The trochanter 20 is preferably spaced approximately 1/16 inch apart above the extractor plate 12.

Effects of the Invention The operation of the pulping apparatus is shown in detail in FIG. First, tank 10 is filled with pulp stock slurry of desired consistency to a depth that is preferably equal to the height of screw 30, but may be somewhat higher. For example, in a pulping tank 10 that has a diameter of 12 feet (3.66 m) and a height of 10 feet (3.05 m), the height including the screw 30 that has a diameter of approximately 1.22 m (48 inches) is approximately 42 inches (1.07 m). ) Trochanter 20 (20), the depth of the material should be at least sufficient to submerge the trochanter and screw, and the water level reached such that the overall height was approximately 1.53 m (5 ft). Show that it is okay to do something. The consistency of the pulp will vary depending on its nature, but favorable results have been obtained with, for example, 16% waste paper, while deinked stocks containing significant amounts of clay or other additives that make the pulp more slippery will give good results. For pulp materials such as, the consistency is 25
% solids can also be high.

The trochanter 20 is rotated counterclockwise as viewed from FIG. As the trochanter rotates in this manner, the concave lower surface 44 of the screw step 33 pulls the pulp stock inwardly in the direction of arrow A, and the spiral passageway of the screw step directs the pulp stock toward the hub portion 12 and the vanes 22. Push downward. At the same time, the rear surface 4 of each screw step
5 has a significantly larger area than the front surface 44, an air foil effect is created in the pulp stock which directs the pulp stock inwardly toward the convex top or rear surface 45, respectively, of the screw step and into the next concave bottom surface 44.
is sucked into the passageway. Therefore, screw 30
The construction and mode of action combine the suction and pressure effects that pull the material radially inward and then towards the trochanter vanes 22.

The air foil action of the convex surface of the screw step effectively counters the tendency of the pulp stock to be forced to move away from the screw before it hits the disintegrating surface 25 of the vanes 22. Furthermore, the peripheral ridges 40 along the lower part of the outer edges of the screw steps act as the sides of the gutter that retains the downwardly flowing pulp and directs it into the passage of the vanes 20, while the outer surface of each peripheral ridge 40 is also involved. The trochanter vane acts as an extension of the repulsion surface.

As the pulp approaches the rear part of the screw step, the increasing radius of the screw core 31 causes the pulp stock to move radially outward at an accelerated speed, because the pulp stock moves with the trochanter due to the guiding action of the peripheral ridge 40. This is because they are forced to continue.
Therefore, by the time the pulp material reaches the space in front of each blade 22, the pulp material has been defibrated over the entire area covered by the defibration surface 25. Furthermore, the accelerated flow velocity of the pulp material in the canals formed by the outer peripheral edge 40, combined with the fact that these canals are constantly increasing in width towards the bottom of the screw, increases the space for feeding the pulp material into these canals. This results in a Bernoulli effect that provides additional suction power.

Since the terminal edge of the screw step 33 coincides with the trailing edge 26 of the trochanter blade 22, the pulp material flows down to the point where the disintegration surface 25 passed well before the approaching trochanter blade 22. Furthermore, the pulp material comes into contact with the extractor plate 12 before being forced outward by the trochanter vanes, so that the trochanter vanes and the extractor plate act on each other to exert mechanical shear on the pulp material at this location. produce an effect.

The pulp is forced outward from the trochanter 20 by the trochanter vanes 22 and moves across the bottom wall 13 to the side wall 14. The trochanter 20 is preferably driven at a speed sufficient to drive the pulp stock up the side wall 14 where the lift occurs, and the pulp stock is then sucked back towards the center of the vessel 10, whereupon the pulp stock is again drawn into the screw stage. It is pulled inward by the rotation of 33. Therefore, the pulp material follows a swirling pattern within the vessel 10 such that all of its constituent fibers are in motion, and a literal hydraulic shear condition exists throughout the volume of the pulp within the vessel.

When a particular batch of pulp stock is sufficiently disintegrated to pass through the holes in the extractor plate 12, e.g. Add enough dilution water to reduce to a low value and then open the control valve in the outlet pipe 16. The pulper is then continued to run until all the good quality fibers have been extracted, adding more water if necessary for a final washing step. Next, the outlet pipe 16 is opened and the valve of the outlet 18 for non-passable material is opened to flush out the non-passable material accumulated in the tank.

Although not shown, it is within the scope of the present invention to modify the sidewall 14 to facilitate the flow of rising material toward the center of the vessel. For example, side baffles such as those described in U.S. Patent Application No. 407,371 filed Aug. 12, 1982 may be used. Alternatively, the vessel may be provided with side walls of a substantially cylindrical cross-section that decrease in diameter upwardly from the bottom plate, giving it the shape of a "cognac bottle". The side walls slope inward,
The trochanter generates a lift and the screw 30 performs a suction action, so that the rising pulp raw material is pumped toward the center of the tank.

Although a preferred embodiment of the invention has been described, it will be understood that the invention is not limited to this embodiment, but may be modified in various ways within the scope of the appended claims.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a pulping tank and a trochanter embodying the present invention, partially in elevation and partially in section; FIG.
Figure 3 is a plan view of the trochanter in Figure 1, Figure 4 is a detailed view of the pulping device in Figure 1, Figure 5 is along line 5-5 in Figure 4. 6 is a sectional view taken along line 6-6 in FIG. 4, FIG. 7 is a detailed view of a typical screw step, and FIG. FIG. 9 is a detailed view of the end of the child blade, and FIG. 9 is a partially detailed view of the blade. 10...tank, 13...bottom wall, 14...side wall, 2
0... Trochanter, 21... Base portion, 22... Feather,
25...Fabricating surface, 33...Screw step part, 35
...Rear edge, 40... Outer ridge, 44... Concave lower surface, 45... Convex upper surface.

Claims (1)

[Scope of Claims] 1 (a) a tank 10 having a bottom wall 13 and a substantially cylindrical side wall 14 extending upward from the bottom wall 13; (b) a central portion of the bottom wall 13; a trochanter 20 mounted on and rotating about a vertical axis, the trochanter having a base portion 21 and a plurality of vanes 22 extending generally radially outwardly from the base portion and having a disintegration surface 25; 20; (c) having a trailing edge 35 extending upwardly from said base portion 21, each screw step 33 having a concave lower surface 44 and a convex upper surface 45 and terminating in said base portion 21; and (d) a plurality of spiral screw steps 33 whose radial width is approximately equal to the radial length of the blades 22; (d) the height of the trochanter 20 is greater than its diameter; (e) The concave lower surface 44 forming the front edge surface of the plurality of screw steps 33 allows the high consistency pulp to pass through and pushes the passed pulp downward toward the disintegration surface 25. (f) each of the rear edge portions 35 of the screw step portion 33;
An apparatus for pulping high-consistency paper pulp raw material, comprising: a peripheral edge 40 extending upward; 2. In the device according to claim 1,
that the vanes 22 are spaced above the bottom wall 13 by a distance such that the trochanter 20 imparts a mechanical shear force to the stock as it rotates in the high consistency stock; A device that converts high-consistency paper pulp raw materials into pulp. 3. In the device according to claim 1,
The bottom wall 13 of the tank 10 is shaped like a truncated cone, and the vane 22 is provided with a similarly conical lower surface for forcing the pulp material upwardly along the bottom wall 13. This equipment converts high-consistency paper pulp raw materials into pulp.