US3459379A - Mechanical pulping apparatus - Google Patents

Description

K. J. BROWN MECHANICAL PULP ING APPARATUS Filed Jan. 18, 1967 a M v i #4 v Z W MM .2 Wm M a a a fizzazzdfirawz BY &4 5 AI'TORNIZYS United States Patent US. Cl. 24138 4 Claims ABSTRACT OF THE DISCLOSURE The disclosed embodiment of the present invention is an apparatus for refining wood chips and pulp which includes a porous plate forming the defibrating surface on one surface thereof and a fluid cavity or reservoir on the other surface thereof to which fluid is supplied under pressure. The fluid passes through the porous plate from the fluid cavity to the defibrating surface. The disclosed exemplification of the invention is a disk refiner, but it is to be understood that the principles of the present invention can be employed in any apparatus for reducing of defibrating wood.

This invention relates generally to a novel pulping apparatus and more particularly to a method and apparatus for supplying fluid to a defibrating surface of a pulping device.

It has been found that in defibrating apparatus for wood chips or pulp that water must be present in the defibrating zone to prevent charring of the wood which will result from the development of excessive heat during the defibrating process. In a disk refiner, for example, it is necessary that heat be present in order to effect proper separation of the fibers of the wood. However, if water or any other fluid is added to prevent charring from the excessive heat that can be developed, care must be taken not to flood the area and dissipate the heat needed for separating the fibers.

Furthermore, uniform distribution of fluid over the surface of the bars of a refiner plate, for instance, is very diflicult to achieve. Consequently, the heat required for separating the fibers may be dissipated in one area of the plate and may be excessive in another area of the same plate and cause charring of the wood. Therefore, it can be realized that it is not only important to maintain the temperature of a defibrating surface below a maximum temperature which would char the wood fibers, but it is also necessary to utilize or maintain a controlled temperature of the surface. High temperatures are necessary for effecting grinding in order to loosen the lignin and binder material between the fibers and a controlled supply of water to the defibrating surface will enable controlling grinding surface temperatures.

In addition, in bleaching processes, homogeneous and uniform wetting of the fibers is essential. Furthermore, the addition of a fluid at the defibrating surface lubricates the same, thus reducing wear.

Although some of the above mentioned problems have been recognized in the past, optimum conditions have not been achieved due to the prior known methods of introducing a fluid to the defibrating zone. Usually, water is supplied to the defibrating zone along with the pulp. This method of adding the water does not provide a uniform distribution of the water over the surface of the bars of a refiner plate, for instance. -It can be readily appreciated that since the feeding of the pulp to the defibrating zone is continuous, the Water cannot be added thereto prior to the addition of pulp. As a consequence, the water does not properly lubricate the defibrating surface.

Apertured outer grinding surfaces have been employed in wood grinders for introducing water into the grinding 3,459,379 Patented Aug. 5, 1969 zone. Such structures provide more uniform distribution of the water in the defibrating zone than that provided by the method of introducing water with the pulp into the defibrating Zone. However, the apertures are susceptible to clogging by wood fibers, resulting in a reduction of fluid at those areas immediately adjacent the clogged apertures. Furthermore, a flooding results immediately adjacent the apertures, resulting in a nonuniform distribution of fluid over the surface of the grinder.

Accordingly, the present invention overcomes the above mentioned difficulties by the provision of a plate which is continuously and uniformly porous and which forms the defibrating surface through which a fluid is supplied under pressure. By supplying the fluid through the porous plate to the defibrating surface, the defibrating surface is continuously lubricated and a uniform distribution of the fluid over the defibrating surface occurs. A fluid cavity or reservoir may be provided in the porous plate to which a fluid is applied under pressure and from which the fluid passes through the porous plate to the defibrating surface.

If the porous plate defining the defibrating surface is disposed for rotation with respect to another defibrating surface, the resulting centrifugal force on the fluid may cause a greater amount of fluid to pass through the porous plate at the peripheral edges thereof. Consequently, it is contemplated by one embodiment of the present invention to provide a plurality of annular chambers within the fluid cavity of the porous plate, such that the outer peripheral chambers are supplied with fluid under less pressure than that exerted on the fluid within the chambers nearer the center of the plate. Consequently, a more uniform distribution of the fluid on the defibrating surface will occur.

The present invention contemplates employing such a porous plate with a defibrating surface and a fluid reservoir either as a rotating member or as a stationary member within a pulping apparatus.

Although porous cutter bars have been employed in refineries in the past, there has been no provision for supplying fluid under pressure through the porous bars to the defibrating surface. In such prior art structures, fluid is either supplied to the defibrating surface along with the pulp supplied thereto or the fluid is derived from the pulp itself. Such porous cutter bars have been employed to increase the rate of refining, but contain the same limitations and disadvantages of the non-porous cutter bars with respect to the distribution of fluid over the surface thereof.

Therefore, it is an object of the present invention to provide a defibrating member for a pulping apparatus which permits the introduction of water or other fluid to the defibrating surface separately of the wood chips or pulp supplied thereto.

Another object of the present invention is to provide a defibrating member for a pulping apparatus which perrnits uniform distribution of :a fluid over the defibrating surface.

A specific feature of the present invention resides in the provision of a defibrating member formed of a porous metal and which forms at one surface thereof a efibrating surface and is disposed for receiving fluid under pressure at the other surface thereof for transmitting such fluid under pressure to the defibrating surface.

Another feature of the present invention resides in the provision of means for supplying the fluid to the porous plate at different pressures at various annular portions thereof to compensate for any centrifugal force exerted on the fluid.

These and other objects, features and advantages of ice the present invention will be more fully realized and understood from the following detailed description when taken in conjunction with the accompanying drawing wherein:

FIGURE 1 is a plan view of a refining plate to be employed in a pulping apparatus and constructed in accordance with the principles of the present invention;

FIGURE 2 is a sectional view taken generally along line IIII of FIGURE 1;

FIGURE 3 is a partial view similar to that of FIGURE 2 and illustrating a modification of the present invention, and

FIGURE 4 is a partial sectional view taken generally along the lines IVIV of FIGURE 1.

Like reference numerals throughout the various views of the drawing are intended to designate the same or similar structures.

With reference to the drawing, and in particular to FIGURE 1, there is shown a refining plate constructed in accordance with the principles of the present invention and adapted to be employed with a similar plate spaced at relatively small distance therefrom and between which pulp is supplied for refining. The refining disk illustrated in FIGURE 1 may be mounted for rotation or may be stationary, as desired. The pulp is generally supplied at a center portion of the disk through the center of the cooperating disk (not shown) and travels radially across the surface of the disk wherein a beating action occurs between the opposed surfaces of the two cooperating disks and exits at a peripheral edge of the disks. As the wood pulp is forced from an inner periphery of the disks to an outer periphery thereof, a defibration occurs and the resulting pulp stock is reduced to a finer state.

The refining disk illustrated in FIGURE 1 is generally formed of a supporting plate 10, a defibrating plate generally designated with the reference numeral 12, and a central cover or guide 14. The defibrating plate 12 is generally formed of a plurality of wedge-shaped segments 16 which are fastened by means of bolts 18 to the supporting plate 10. Each of the segments 16 has an upper surface thereof containing a plurality of grooves 20 and forming between each of the grooves a plurality of bars 22. This general organization forms one refining plate of a pulping apparatus or the like.

The novel features of the present invention are realized by the construction of the segments 16 and the structure for supplying a fluid thereto. In particular, each of the segments 16 is constructed of a porous material, such as a porous metal, which is sufficiently porous to permit a fluid to pass therethrough. Such fluids may be either water or bleaching agents or a combination of both. Preferably, the porosity of the segments 16 is continuously uniform throughout the entire volume of each.

As shown in FIGURE 2, the supporting plate 10 includes an upstanding flange 24 at the peripheral edge thereof for receiving the defibrating plate 12, formed of the individual segments 16, therein. Each of the segments 16 includes a flange 26 extending substantially around the entire periphery of each from a bottom surface thereof. The flanges 26 of the segments 16 abut with an upper surface of the supporting plate 10 and define fluid cavities or reservoirs 28 therewith. The flanges 26 extend around the outer arcuate edges and along the side edges of each of the segments 16. The inner peripheral edges of each of the segments 16 are conformably shaped to receive the peripheral edge of the cover 14 therein, such that the cover 14, the segments 16, and the supporting plate 10 form a closed fluid cavity or reservoir to which fluid may be supplied under pressure.

As illustrated in FIGURE 2, a fluid conduit 30 extends through the supporting plate 10 and is disposed in fluid communication with the cavities 28. The conduit 30 is connected to a fluid coupling or rotary joint 32 which is employed only when the disk is disposed for rotation. The conduit 30 is mechanically connected to a shaft 34 which is disposed for being driven from a motor or other source of motive power (not shown). Water and/or bleaching agents are supplied to the respective cavities 28 from a tank, generally designated with the reference numeral 36, which is connected to the fluid coupling 32 by means of a conduit 38.

The water and/or bleaching agents are supplied to each of the cavities 28 under pressure from the tank 36 and through the conduit 38, the fluid coupling 32, and the conduit 30. The fluid within the cavities 28 is forced through the porous material forming the defibrating plate 12 to the defibrating surface formed of the grooves 20 and bars 22. In this manner, the fluid under presure will reach the defibrating surfaces independently of the pulp supplied thereto. Therefore, a more uniform distribution of the fluid over the surface of the bars of the refiner plate will result.

If the refining disk of the present invention is mounted for rotation, centrifugal force will act on the fluid within the cavities 28 and a greater pressure will be exerted on the fluid at the outer peripheral edge of the defibrating member 12. In order to provide a more uniform distribution of the fluid, the pressure on the fluid at the outer peripheral edges of the member 12 should be reduced as compared to the pressure at the inner portions thereof.

In order to provide such a result, the present invention contemplates the structure illustrated in FIGURE 3 wherein a plurality of arcuate flanges 40 and 42 extend from a bottom surface of the segments 16 and abut with an upper surface of the supporting plate 10 within each of the cavities 28. In particular, the flange 40 with the flange 26 defines a cavity 44 and with the flange 42 a cavity 46. The flanges 42 of each of the segments 16 define a central cavity 48 to which is supplied the fluid under pressure by means of a conduit 30. Each of the flanges 40 and 42 are also formed of porous material, such that fluid will pass through each, but a pressure drop will result across the thickness of each. Therefore, the fluid within the chamber 46 will have a predetermined pressure exerted therein which will be equal to the pressure on the fluid within the cavity 48 less the pressure drop existing across the thickness of the flange 42. Similarly, the pressure on the fluid within the chamber 44 will be equal to the pressure on the fluid in the chamber 46 less the pressure differential existing across the thickness of the flange 40. If the pressure differential across the flanges 40 and 42 are equal to the increase in the pressure on the fluid as a result of the centrifugal force thereon, a more uniform distribution of fluid will occur at the defibrating surface of the segment 16. A greater number of flanges and chambers may be provided as desired.

The principles of the invention explained in connection with the specific exemplifications theerof will suggest many other applications and modifications of the same. It is accordingly desired that, in construing the breadth of the appended claims they shall not be limited to the specific details shown and described in connection with the exemplifications thereof.

What is claimed is:

1. In a pulping apparatus for defibrating a fibrous material, a defibrating member comprising a circular plate disposed for rotational movement,

a fluid inlet connected at the center of said plate, and

a porous member conformably shaped to said plate including an annular flange abutting said plate, said porous member secured to said plate and defining a closed chamber in fluid communication with said fluid inlet and including an outer surface forming a defibrating surface, and means for limiting the radial movement of fluid in said chamber to permit more equalized distribution of fluid at the external surface of said porous member.

2. A defibrating member as defined in claim 1 wherein in said porous member is continuously porous throughout the entire volume thereof.

3. A defibrating member as defined in claim 1 wherein said limiting means includes a plurality of flanges ex- 2,751,157 6/1956 Meyer 24138 tending from an inner surface of said porous member to 2,774,201 12/1956 Harrington 5 1267 said plate and defining a plurality of fluid-receiving cham- 2,826,019 3/1958 Garrison 5l267 bers therebetween.

4. A defibrating member as defined in claim 3 wherein 5 FOREIGN PATENTS 531d flanges are P 526,434 6/ 1956 Canada.

References Cited ROBERT c. RIORDON, Primary Examiner UNITED STATES PATENTS D. G. KELLY, Assistant Examiner 1,795,603 3/1931 Hussey 241--296 X 10 2,139,933 12/1938 Chenoweth 241-38 US. Cl. X.R.

2,599,543 6/1952 COghill 241-296 X 2,745,229 5/195'6 Brady 5l267

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