US3086453A - Continuous disc type press - Google Patents

Description

April 23, 1963 A. J. A. ASPLUND CONTINUOUS DISC TYPE PRESS 2 Sheets-Sheet 1 Filed Oct. 24, 1958 April 23, 1963 A. J. A. ASPLUNID CONTINUOUS DISC TYPE PRESS 2 Sheets-Sheet 2 Filed Oct. 24, 1958 United StatesPatent ()fifice 3,086,453 CONTINUOUS DISC TYPE PRESS Arne Johan Arthur Asplund, 11 Orevagen, Bromma, Sweden Filed Oct. 24, 1958, Ser. No. 769,366 Claims priority, application Sweden Oct. 28, 1957 9 Claims. (Cl. 100-106) This invention relates to a continuous disc type press for expelling liquid from wet material such as liquid 3,086,453 Patented Apr. 23, 1963 to this reduction of the fibre losses the cross section of the perforations in the discs may be made larger than suspensions of cellulose fibres, bark particle-s, peat and the like, and of the kind comprising two spaced perforated pressing discs disposed substantially co-axially on shafts having their axes disposed at a slight mutual inclination and rotating in the same direction, at least one of the discs being axially movable and being subjected to forces tending to press the discs together and wherein the material to be treated is fed between the discs at a zone where the disc interspace is relatively large and the compression of the material is effected while being carried along by the rotation of the disc to the narrowest zone of said interspace.

Usually the shafts of the discs are approximately horizontal and the widest zone of the interspace, the socalled gap, will then be positioned above the shafts whereas the narrowest zone of the interspace, or the socalled nip, is disposed below said shafts.

In presses of this kind hitherto constructed the suspension of material and liquid is fed to the press by means of a screw conveyer or a similar device. If the suspension is relatively dilute it must be thickened in front of the screw conveyer. This thickening operation is necessitated by the fact that thin suspensions manage to pass through the space between the perforated discs before a layer of the material, such as fibres, bark particles and the like, effective as a filter layer has been built up, and that the suspension will not be sufficiently thickened to be caught by. the nip.

One object of the invention is to provide a press adapted to produce effective compression in the press of suspensions sufiiciently diluted as to be capable of being pumped to the press so that conduits may be used for conveying the suspension to the inlet of the press instead of a screw conveyor which implies considerable reduction in the costs of construction, operation and maintenance.

According to one main feature of the present invention the discs are constructed to provide behind the perforations peripherally spaced cells preferably of sector-shape communicating with the disc interspace through the perforations and, also with a device, such as a valve member, acting to connect the cells to a source of vacuum or to an outlet during part of each revolution of the discs.

By this construction a vacuum may thus be created in the cells independently of the expression of liquid effected while the material is passing from the gap to the nip, whereas the finally treated material is discharged from a zone of the interspace which communicates freely with the surrounding atmosphere so that the cells through the perforations are then open to atmospheric pressure. The vacuum vigorously promotes the thickening of the suspension since the separation of the liquid is produced more quickly.

According to another main feature of the invention a vacuum may be used for sucking out two liquid fractions separately from one another. The first fraction consists of liquid which is separated through that cell or those cells which first receive the suspension entering the press during the rotation of the press discs. This first fraction separated has a comparatively large content of dry substance, such as fibres, which may be recovered, for instance, by the fraction being re-cycled to the press. Due

hitherto. In practice this feature implies that the press can operate with a high capacity, calculated on the discharged dewatered substance. The second fraction separated is relatively free from fibres and may be subjected to an evaporation process for recovery of chemicals dissolved or suspended in the liquid, which is usually water.

Further objects and advantages of the invention will become apparent from the following description, considered in connection with the accompanying drawings, which form part of this specification and in which:

FIG. 1 shows a side elevation partly in section of a press constructed according to the invention, the section being taken along the line I-I of FIG. 2, FIG. 2 is a transverse section along the line IIII of FIG. 1.

Referring to the drawings numeral 10 designates a supporting frame of a press including two press discs 12, 14 rotatably mounted on said frame. Each disc has a hub portion 16 rigidly secured to a flange 18 of a shaft 20 by means of a ring member 27 and bolts 24. Within the frame 10 and a bearing housing 26, which is attached to the frame by means of bolts 25, is arranged a sleeve 28 contacting the bearing housing along two preferably cylindrical surfaces, 30, 32 and axially slidable in relation to said housing. The sleeve 28 is held against rotation by means of a bolt 34 entering an axially elongated aperture 36 in said sleeve. The shaft 20 is rotatably mounted in the sleeve 28 by means of two bearings '38, 40. The two bearings and the sleeve 28 are thus axially fixed relatively to the shaft 20.

The discs 12 and 14 have their shafts mounted substantially coaxially at adjacent ends, the shafts being slightly inclined to one another in the vertical plane and preferably also in the horizontal plane. In the embodiment shown the opposing faces of the discs are disposed so as to form an inwardly tapering interspace. Due to the slight inclination of the two shafts 20 the discs form an interspace which is wider above than below the shafts. The maximum interspace will hereinafter be referred to as the gap and the minimum interspace as the nip. When the press discs rotate counter-clockwise as viewed in FIG. 2, the gap and the nip may be positioned along a line 41 which is angularly displaced relatively to a vertical longitudinal plane through the press. The discs 12, 14 are rotated in the same direction and with the same slow speed by means of a transmission, one for each disc. A transmission gear wheel 42 secured to each disc is shown in the figures.

The discs are provided with peripheral walls 44 which, together with the hub portion 16 bound a cavity divided into a plurality of peripherally spaced sector-shaped cells 46 by means of radially extending partitions 45 or the like. Each cell 46 thus has circumferential and side walls sealing the cell with respect to the atmosphere and is covered by a screen plate 48 on the active face of the disc. One screen plate may be provided for each cell or may cover several cells. The cells are separated from one another or said face by radial ribs 50 located opposite the partition 45. The outer surfaces of the ribs 50 and the plates 48 are flush or approximately flush with one another. The plates 48 are perforated as indicated at 52 in FIG. 2, and the discs are formed with bores 54 providing communication of the various cells with the rear face of the plates. The disc face contacted by the plates may be provided with small transverse channels so as to establish communication between the perforations 52 of the plates and the bores 54 which latter are substantially less in number. The discs are stiffened by webs 56 between which are located the bores 54.

The interspace between the discs is covered externally by an annular casing 58 and internally by a sleeve 60 both members having a greater axial width at the upper edge than at the lower edge of the discs corresponding to the varying width of the interspace. The suspension to be treated is introduced through an inlet 62 disposed adjacent the gap, and the treated material is discharged through an outlet 64 disposed beyond the nip reckoned in the direction of rotation of the discs indicated by the arrow 66 in FIG. 2. Between the inlet 62 and the outlet 64 a section of the interspace is occupied by a doctor 68 preferably in sealing contact with the discs by means of pressure pads 70 made of resilient material, such as rubber, and disposed in recesses in the doctor.

Within each of the cells 46 pipes 72 extend from the hub portion 16 outwards to the periphery of the cells and preferably terminate at the trailing side of the cell which is lowermost during the downwards diverted part of the rotation of the discs. From the respective pipes 72 channels 74 extending radially inwardly are formed in the flange 18 of the shaft and in a bush 76 secured to the flange. In the bush is arranged a valve member having the form of a stationary slide member 78. From the slide member 78 a tube 80 attached to the member 78 extends through the hollow interior of the shaft to a conduit 82 disposed externally of the shaft and communicating with a vacuum pump 84. The slide member 78 is provided with a plurality of radial channels 86 connecting the interior of the tube 80 with the pipes 72 located in the lower section of the press during the rotation of the discs. Consequently the pipes 72 in the cells designated 46a-d in FIG. 2 communicate with the vacuum pump 84 through the tube 80 while the remaining cells are disconnected from the pump 84.

Another group of radial passages 88 from the individual cells 46 extend through the hub 16, the flange 18 and the bush 76 into the slide member 78. These passages thus open at the inner periphery of the cells. The slide member 78 has a number of radial channels 90 mating with the passages 88, and opening into an annular chamber 92 bounded by the tube 80 and a tube 94 disposed co-axially with and surrounding the tube 80. The annular chamber communicates with a conduit 96 connected to a second vacuum pump 98. The pumps 84 and 98 may be used to create a negative pressure in the cells of the order of 4 or meters of water column.

The conduits 82 and 96 are connected to a sleeve 100 projecting into the end portion of the shaft 20 and held stationary by means of an arm 102 engaging a pin 104 secured to the stationary frame. The tubes 80 and 94 have their outer ends tightly connected to the sleeve 100. Thus the slide member 78 is thereby intimately connected to the sleeve 100 and may be withdrawn from the shaft 20 by means of said sleeve. The slide member 78 may be adjusted to various angular positions in order to change the position of the passage openings.

The channels 90 in the slide member are so disposed as to provide communication between the annular chamber 92 and only those cells which first receive the incoming liquid suspension. These cells may, for example, be those designated 46e-g in FIG. 2. The other cells are cut off from the channels 90.

One or more of the passages 88 communicating with the cells in positions 46a-d during rotation of the discs 12, 14 may be in communication with the outer atmosphere through small passage ways 106 provided in the slide member 78, the annular chamber 108 between the tube 94 and the shaft 20, and a channel 110 in the sleeve 100 in order to supply air to said cells. A narrow tube 112 for pressure liquid such as water leads to one or more radial passages 114 in the slide member 78 opening into the sealing surf-aces between the slide member and the bush 76. The supply of water under pressure to the sealing surfaces and grooves formed in these surfaces in known manner counteracts undesired leakage between the various systems of passages in the multi-way valve formed by the slide member 78 and the bush 76.

The counter-pressure acting axially on the discs 12, 14 and opposing the pressure exerted by the material under compression may with advantage be estabilshed by means of hydraulic servo-systems 116 positioned below the shafts 20. The fluid pressure in the various servo-systems is transferred through the intermediary of a plunger 118 to one end of a lever 120 mounted on a pivot pin 122 carried in a fixed bracket 124. Between the ends of the lever 120 a backing roller 126 is rotatably mounted, said backing roller having a curved or part-spherical roller face 128 adapted to co-operate with a roller track 130 of corresponding transverse contour formed in a ring member 132, secured together with the gear wheel 42 to the wall 44 of the disc by means of bolts 134. Preferably three servo-systems are mounted to cooperate with each disc 12 and 14, respectively. By means of the lever 120 the pressure exerted on the ring 132 by the backing roller 126 will be twice as large as the pressure acting in the servo-system. This device is described more in detail in the specification of my copending patent application No. 769,367 of even date herewith and to which reference may be made for a fuller description.

A labyrinth seal 136 is provided between the external casing 58 and the discs 12 and 14. Liquid leaking out through said seal is collected in a gutter 138 which has a drain 140 at the bottom.

The thin suspension of, for instance, water (liquor) and cellulose fibres is preferably pumped in through the inlet 62 and enters the interspace between the discs at the top section of the interspace as shown in FIG. 2. The cells 46e-g adjacent the inlet communicate with the pump 98 and a strong removal of water by suction is effected through the cells exposed to the vacuum. Durmg this step of the treatment a fibre layer settles on the screen plates 48, but as this layer is still comparatively thru a rather large quantity of the fibres follows the water sucked out. These fibres are recovered, for example by re-cycling the fraction passing the pump 98 to the press where it is mixed with suspension not yet treated.

When the cells pass over from, for example, the position 46g to 46a the connection with the pump 98 is interrupted and a communication is established between the cells and the pump 84. The fraction now expressed from the pulp suspension is substantially free from fibres due to the fact that the fibre layer on the disc screens 48 has been built up to a greater thickness. At the same time an is ntroduced into the cells through the passage way 106 with throttling, so that the incoming air quantity is substantially equal to the water quantity sucked away in unit time. In this manner the water may be discharged without any risk of destroying the vacuum prevailing in the cells. The expression of water is continued until the material has passed the narrowest section, that is the nip, located at the lower part of the line 41. The discs after having passed this line, again diverge, and when the material strikes the doctor 68 it is scraped off from the discs and discharged through the outlet 64. When the cells are in this section of a revolution they communicate with the outer atmosphere and are also cut off from both vgcuum pumps by means of the valve member described a ove.

In some cases a single vacuum system may be sufiicient. In this case the cells may be provided with pockets at their trailing portions, each pocket starting from the rear wall of the cell, at the portion of the cell located radially nwardly and extending radially outwardly but terminatlng slightly spaced from the peripheral external wall of the cell. While the cell rotates upwardly as viewed in FIG. 2, liquid will collect and be retained in the pocket. The liquid may then be conducted away through a channel passing inwardly at the hub portion of the disc and 23 through a valve element to a drain, when the cell is positioned at another part of the revolution, for example above the shaft. The sources of vacuum may be replaced by devices permitting the liquid in the cells to flow ofi by gravity, for example by removal of screws plugs 135 allowing the pump 84 to be dispensed with. In a similar manner escape due to gravity may be arranged through the passages 88 so as to render the pump 98 superfluous.

While one more or less specific embodiment 'of the invention has been shown and described it is to be understood that this is for purpose of illustration only and that the invention is not to be limited thereby, but its scope is to be determined by the appended claims.

What I claim is:

1. A disc type press for expressing liquid from a liquid suspension of cellulose fibres, bark particles, peat or the like, comprising two facially opposed discs provided with perforations and arranged substantially coaxially, which discs are urged toward one another, each of the discs having a slight inclination of its axis to thereby provide a relatively large space between the upper portions of the discs and a smaller space between the lower portions,

said discs being rotated in the same direction, the material to be compressed being introduced through an inlet between the discs where the space between the latter is comparatively large, the expressing of liquid from the material taking place while the material is carried by the rotation of the discs, :along the narrowest portion of the space between the discs and thereafter discharged, the discs being each provided with a plurality of separate peripherally spaced cells behind the perforations, said cells being formed by intermediate walls extending radially and axially from the discs on the sides thereof remote from the space between the discs, said cells being closed by walls extending substantially parallel to the discs on opposite sides of said intermediate walls, said cells in each disc being separated from one another and being of sector shape, the cells having one side in communication with the perforations and the other side provided with individual pass-ages so located that draining the liquid from one cell takes place during only a portion of one rotation of the discs, a suction source for aiding in said draining, each of said cells being provided with two outlet passages arranged to drain the liquid from the perforations in the discs during different portions of the rotational cycle whereby the liquid will form two different fractions.

2. A press according to claim 1 characterized by the fact that the two outlet passages from a single cell are each connected to its own channel which extends through an axle in the discs.

3. A press according to claim 1 characterized by the fact that the two outlet passages belonging to one cell are each connected to its own respective vacuum source.

4. A press according to claim 3 characterized by the fact that one of the outlet passages belonging to one cell joins said cell at the inner periphery of the same while the other outlet passage for said cell joins the same at its outer periphery.

5. A press according to claim 4 characterized by the fact that the first-mentioned outlet passage is arranged to connect with the corresponding channel in the axle only when the cell, during its rotation is located above the axle and the other outlet passage connects with its channel only when the cell is located below the axle.

6. A press according to claim 5 characterized by the fact that a stationary slide is arranged in the axle, said slide abutting tightly against the axle, the portion of the axle against which the slide abuts being provided with channels corresponding to the respective outlet passages of the cells in order to establish connection with the axially-extending channels at predetermined times.

7. A press according to claim 6 characterized by the fact that the slide is arranged to admit air under throttling to one or more of the cells through a channel when outlet passages joining the outer periphery are connected with a vacuum source.

8. A press according to claim 6 characterized by the fact that on the opposing sides of the discs there are plates having perforations the size of which corresponds to that of the cells and by means of which communication is established with the cells through channels in the discs.

9. A disc type press for expressing liquid from liquid suspension of cellulose fibres, bark particles, peat or the like, comprising, two facially opposed discs provided with perforations and arranged susbtantially co-axially, which discs are urged toward one another, each of the discs having a slight inclination of its axis to thereby provide a relatively large space between the upper portions of the discs and a smaller space between the lower portions, said discs being rotated in the same direction, the material to be compressed being introduced through an inlet between the discs where the space between the latter is comparatively large, the expressing of liquid from the material taking place while the material is carried by the rotation of the discs along to the narrowest portion of the space between the discs and thereafter discharged, the discs being each provided with a plurality of separate, peripherally spaced cells behind the perforations, said cells being formed by intermediate walls extending radially and axially from the discs on the sides thereof remote from the space between the discs, said cells being closed by walls extending substantially parallel to the discs on opposite sides of said intermediate walls, said cells in each disc being separated from one another and being of sector shape, the cells having one side in communication with the perforations and the other side provided with individual outlet passages so located that draining the liquid from one cell takes place during only a portion of one rotation of the discs, a hollow axle provided in each of the discs to provide a channel, the outlet passages from the individual cells being in communication with the channel only during a portion of one rotation of the discs.

References Cited in the file of this patent UNITED STATES PATENTS 241,243 Selwig May 10, 1881 670,963 Logemann Apr. 2, 1901 2,084,229 Van Maaven June 15, 1937 2,226,926 Gordon Dec. 31, 1940 2,617,354 Ingalls Nov. .11, 1952

Claims (1)

1. A DISC TYPE PRESS FOR EXPRESSING LIQUID FROM A LIQUID SUSPENSION OF CELLULOSE FIBRES, BARK PARTICLES, PEAT OR THE LIKE, COMPRISING TWO FACIALLY OPPOSED DISCS PROVIDED WITH PERFORATIONS AND ARRANGED SUBSTANTIALLY COAXIALLY, WHICH DISCS ARE URGED TOWARD ONE ANOTHER, EACH OF THE DISCS HAVING A SLIGHT INCLINATION OF ITS AXIS TO THEREBY PROVIDE A RELATIVELY LARGE SPACE BETWEEN THE UPPER PORTIONS OF THE DISCS AND A SMALLER SPACE BETWEEN THE LOWER PORTIONS, SAID DISCS BEING ROTATED IN THE SAME DIRECTION, THE MATERIAL TO BE COMPRESSED BEING INTRODUCED THROUGH AN INLET BETWEEN THE DISCS WHERE THE SPACE BETWEEN THE LATTER IS COMPARATIVELY LARGE, THE EXPRESSING OF LIQUID FROM THE MATERIAL TAKING PLACE WHILE THE MATERIAL IS CARRIED BY THE ROTATION OF THE DISCS, ALONG THE NARROWEST PORTION OF THE SPACE BETWEEN THE DISCS AND THEREAFTER DISCHARGED, THE DISCS BEING EACH PROVIDED WITH A PLURALITY OF SEPARATE PERIPHERALLY SPACED CELLS BEHIND THE PERFORATIONS, SAID CELLS BEING FORMED BY INTERMEDIATE WALLS EXTENDING RADIALLY AND AXIALLY FROM THE DISCS ON THE SIDES THEREOF REMOTE FROM THE SPACE BETWEEN THE DISCS, SAID CELLS BEING CLOSED BY WALLS EXTENDING SUBSTANTIALLY PARALLEL TO THE DISCS ON OPPOSITE SIDES OF SAID INTERMEDIATE WALLS, SAID CELLS IN EACH DISC BEING SEPARATED FROM ONE ANOTHER AND BEING OF SECTOR SHAPE, THE CELLS HAVING ONE SIDE IN COMMUNICATION WITH THE PERFORATIONS AND THE OTHER SIDE PROVIDED WITH INDIVIDUAL PASSAGES SO LOCATED THAT DRAINING THE LIQUID FROM ONE CELL TAKES PLACE DURING ONLY A PORTION OF ONE ROTATION OF THE DISCS, A SUCTION SOURCE FOR AIDING IN SAID DRAINING, EACH OF SAID CELLS BEING PROVIDED WITH TWO OUTLET PASSAGES ARRANGED TO DRAIN THE LIQUID FROM THE PERFORATIONS IN THE DISCS DURING DIFFERENT PORTIONS OF THE ROTATIONAL CYCLE WHEREBY THE LIQUID WILL FORM TWO DIFFERENT FRACTIONS.

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