US3086454A - Continuously operating press apparatus - Google Patents

Description

April 23, 1963 A. J. A. ASPLUND 3, 8

CONTINUOUSLY OPERATING PRESS APPARATUS Filed March 18, 1960 5 Sheets-Sheet 1 Fig.1

April 23, 1963 A. J. A. ASPLUND CONTINUOUSLY OPERATING PRESS APPARATUS Filed March 18, 1960 5 Sheets-Sheet 2 I mvgnmm drnegE/hn April 23, 1963 A. J. A. ASPLUND counuuousu OPERATING PRESS APPARATUS 5 Sheets-Sheet 3 Filed March 18,

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INVENTOR.

drrae/ (lb/gm drif A ril 23, 1963 A. .1. A. ASPLUND 3,086,454

CONTINUOUSLY OPERATING PRESS APPARATUS Filed March 18, 1960 5 Sheets-Sheet 4 Fig. A

INVENTOR.

April 1963 A. J. A. ASPLUND 3,086,454

CONTINUOUSLY OPERATING PRESS APPARATUS Filed March 18, 1960 5 Sheets-Sheet 5 INVENTOR. dme Jaigm drZ/zu ds vlzzm' tates 3,036,454 CONTINUOUSLY OPERATING PRESS APPARATUS Arne Johan Arthur Asplund, 11 Orevagen, Bromrna, Sweden Filed Mar. 18, 1960, Ser. No. 15,950 Claims priority, application Sweden Mar. 23, 1959 4 Claims. (l. 100-121) obtained in breweries. The invention may also be used in the recovery of pressing of cane juice in the production of sugar.

The product desired to be recovered by the pressing operation may be constituted of either the liquid or the suspended solid material or both the liquid and the material. This last-mentioned result is desired, for example, in the production of chemical or semi-chemical cellulose pulp wherein a suspension of fibers in water is formed which water also contains valuable chemicals. After separation of the two components said chemicals are recovered by an evaporation process.

It is known in prior art to build a press of the kind in consideration having an interspace confined by two rotatable pressing members and diminishing in size in the direction of rotation so as to cause the suspension of material to be subjected to a gradually increasing pressure While the liquid is expelled through screen portions formed in one or the other or both press members.

One primary object of the invention is to provide a press apparatus of the type in consideration which is simpler and consequently cheaper to construct than those hitherto known.

A further object of the invention is to provide a press apparatus rendering it possible to exert a highly uniform pressure on the material to be dried. Still a further object of the invention is to provide a press apparatus permitting operation with high pressures and having high capacity.

According to a main feature of the invention one of the rotatable press members is mounted eccentrically within the other rotatable press member in such a manner as to form an interspace between said members having a crescent-shaped cross-section. In a structure with horizontal shafts the shaft of the inner press member is displaced eccentrically in relation to the shaft of the outer press member and also in relation to the direction of relative rotation in such a manner as to cause the minimum interspace or the nip to be located above the horizontal plane through the first-mentioned shaft and on that side of the apparatus Where the members during rotation are moving upwards. Preferably, the two press members are radially displaceable relatively to one another in order to allow adjustment of the magnitude of the nip, and suitably the direction of the displacement is horizontal.

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 of which:

atent line I-I of FIG. 3 through a press apparatus constructed according to the invention and intended for separation of suspended pulp and a liquid containing chemicals from one another.

FIG. 2 is a cross-sectional view following line II-II of FIG. 1.

FIG. 3 is an end elevation of the press apparatus seen from the right to the left of FIG. 1, some parts of the apparatus being shown in section taken on line III-III of said figure.

FIG. 4 is a diagrammatic and part-sectional view of a device for adjustment of the position of the inner press member.

FIG. 5 is a sectional view similar to that shown in FIG. 2 through a press apparatus constructed according to a slightly modified embodiment of the invention.

Referring to the drawings, reference numeral 10 denotes a casing or frame of a press enclosing two substantially cylindrical press members generally denoted by 12 and 14, respectively. The inner member 12 will hereinafter be designated as the cylinder 12 and the outer member 14 as the drum 14. The cylinder '12 is rigidly connected with centrally mounted journals 16 and 18, respectively, carrying bearings denoted by 20 and 21, respectively. The drum 14 is supported externally by preferably three pairs of rolls 22, 24 and 26 adapted to co-operate with two bearing rings 28 shrunk on the external surface of the drum. The rolls are in pairs carried on shafts 29, 30

and 31 mounted in bearings 32 secured to the frame 10.

The cylinder 12 is mounted radially inside the drum 14, the mounting of both said parts being carried out in such a manner as to position their axes ecceutrically relatively to one another. They are driven to rotate in the same direction counter-clockwise according to the arrow 24 in FIGS. 2 and 5 with the same or possibly slightly different speeds of their circumferential screen surfaces which speed may be a few revolutions per minute. During this movement the spacing between two opposite points on their cylindrical surfaces varies and attains a maximum value at the so-calledgap indicated at 36 in FIGS. 2 and 5 and a minimum value at a diametrically opposite point the so-called nip 38. From a power source (not shown) a transmission member formed in the embodiment shown as a chain 40 passes over a sprocket 42 rigidly secured to the shaft 30 of the rolls 24. Between said sprocket and another sprocket 44 carried on the shaft 38 of the upper pair of rolls 26 a chain 46 passes so that two of the three pairs of rolls in the illustrated embodiments are driven. The cylinder 12 is suitably driven from the same power source as the drum by means of a chain 48 passing over a sprocket 50 carried on a shaft 52 which in turn is mounted in the frame 10. Secured to the shaft '52 is a furtherspro'cket 54 which by means of a chain 58 is in driving connection with a sprocket 56 rigidly secured onto the journal 16 of the cylinder 12. The sprocket 50 is preferably located vertically below the center of the larger sprocket 56.

The relation between the gap 36 and the nip 38 is variable due to means being provided to displace the parts 12 and 14 relatively to one another. In the embodiments shown the cylinder 12 is displaceable horizontally within the frame 10. Said frame is on each side provided with an aperture bounded at its top and its base by straight guides 60 or a cover 62 provided on said guides and made of a material with suitable gliding properties such :as Teflon. Blocks 64, 65 are mounted with their inner surface on the external ring of the bearings 20 and 21, respectively, and they are on their outer surface provided with straight guide faces intended for co-operation with the guides 60, 62. Provided on either side of both bearings and the guide members are covers 66, 68 having a rectangular outer contour. The horizontal displacement of the cylinder 12 is effected by hydraulic power in a manner which shall be described more in detail further below in this specification.

The interspace 69, the cross-section of which is crescentshaped and which viewed in the direction of rotation extends from adjacent the gap 36 to the nip 38 between the cylinder 12 and the drum 14 is laterally closed by stationary shield plates 70. Said shield plates are sealed towards the suitably fiat lateral end faces of the cylinder and the drum by sealing members 72 and 74, respectively, and are adjusted relatively to said sealing members by means of screws 76. It is of substantial importance that the sealings fit as exactly as possible so as to reduce leaking out of fibrous material to a minimum. The fibrous suspension to be treated in the press apparatus is introduced into the cross-sectionally crescent-shaped interspace 69 suitably from both sides thereof through a conduit 78 opening through the shield plate 70. The interspace 69' is closed above the gap 36 or the supply conduit 78 by means of a partition wall 80. Since the gap 36 varies in size the partition wall 80 must be capable of performing its sealing function in spite of the varying spacing between the cylindrical screen surfaces of the cylinder and the drum. This is accomplished in the embodiments shown by tongues 82 made of rubber or Teflon and engaging the cylindrical surfaces in consideration.

The drum 14 carries on its inner wall a cylindrical screen 84 which may he supported by a sleeve 86' which on its inner face is formed with a large number of peripherally extending shallow grooves 88. Provided around the sleeve 86 is a strong jacket 90 formed with circumferentially extending flanges 92 supporting the sleeve 86. The inwards projecting flanges 92 are traversed by axial channels 94 and the center portion of the jacket 90 is formed with radial apertures 96. The liquid which passes through the screen 84 follows the shallow grooves 88 and axial slots 98 each of which connects a plurality of grooves with the outer face of the sleeve 86. Said slots 98 are arranged, as will be seen from FIG. 1, in groups displaced relatively one another both axially and peripherally in order to avoid inappropriate weakening of the sleeve. The expelled liquid continues its flow through the channels 94 to the discharge apertures 96. Located at the base part of the press is a collecting trough 100 with a drain 102 for recovery of the liquid to be treated further.

The inner cylinder 12 may be formed with surfaces of substantially the same kind as those of the drum 14 for separating and collecting the expelled liquid. The cylindrical inner Wall of the cylinder 12 is thus formed of a screen 104 supported by a sleeve 106, which latter is provided with a great number of shallow grooves 108 communicating with the interior of the sleeve by means of groups of axial slots 110. Said slots open into pockets 1'12 limited by mutually parallel walls or partitions 114 and radially projecting walls or partitions 116 having foot-like prolongations .118. In the embodiments shown the number of pockets 112 around the circumference is eight but may, of course, be any other suitable number. The individual pockets are thus separated from one another both in the axial and in the peripheral directions. Adjacent the hub they communicate through radial bores 120 with an axial inner bore 122 extending through the cylinder and its two journals 16 and 18. The bore 122 may be subdivided by means of an elongated partition member 123 participating in the rotation and divided into eight channels one for each row of pockets 112 so as to prevent any overflow of liquid between the various radial rows of pockets. To one or both journals a stationary drain conduit 124 opening into the trough 100 is connected.

The suspension which in the case envisaged is assumed to consist of pulp fibers contained in a liquid containing chemicals in a concentration of solid particles of about 5 to 15 percent, for example, is introduced through the conduit or conduits 78 into the interspace 69 between the cylinder 12 and the drum 14. If desired the supply may be effected under superatmospheric pressure such as several kilograms per square centimeter, for example. While the cylinder and the drum slowly rotate in the direction indicated by the arrow 34, the liquid will be expressed through the two screens 84 and 104. The perforations of the screen may have so large diameter as one or several millimeters, since pulp fibers immediately deposit over the perforations during the initial part of the pressing operation and thereby form a kind of filter. During the movement of the two screens in counter-clockwise direction the spacing between them is reduced and more and more liquid is expelled. In the nip 38 the compression and the pressure force reach their maximum value and the consistency of the pulp may have been concentrated to about 45 to 50 percent. The liquid expelled through the screen 84 escapes through the apertures 96 to the drain 102. The liquid which is separated through the inner screen 104 is during the passage between the gap and nip forced inwards through the pockets 112 to the branch channels of the bore 122 and escapes through the conduit or conduits 124 to the drain 102. Due to the specific form of the pockets 112 the liquid during the passage of the pockets through the upper part of the press is prevented from returning to the dried pulp substance fed to said upper part. Said pulp substance is removed from the press by means of a screw 126. Arranged around the screw is a doctor plate 128 the edges of which scrape along the screens 84 and 104 to remove fibrous substance deposited thereon.

As in particular will be evident from FIG. 2, the nip is located above the level of the horizontal middle plane of the press and on the side where the cylindrical screens during their rotation move upwardly. The nip 38 may form an angle of about 30 with the horizontal plane viewed from the shaft of the cylinder 12. By this arrangement it is ensured that the expelled liquid by its own gravity is prevented from returning to the concentrated solid substance.

As already mentioned, the pressure is produced by hydraulic means. Each of the bearings 20, 21 supporting the inner cylinder 12 is subjected to the action of a hydraulic servo-motor denoted by 130 and 132, respectively (see FIGS. 3 and 4). Each of said servo-motors has a cylinder within which a plunger denoted by 134 and 136, respectively, is displaceable. The plunger may house a central tap 138 having some capacity of automatic re-adjustment relative said plunger. Oil is supplied to the plunger chamber of the servo-motors by conduits 140 and 142, respectively. For removal of leakage oil an annular groove 144 and a drain 146 may be provided in the casing of the servo-motor.

It is of great importance that the pressure acting on the cylinder 12 is automatically adjusted according to the distribution of the material to be separated within the interspace 69 in the axial direction thereof. If, for example, when starting the press more material has collected at one side of the interspace than at its other side, the cylinder at that side, which has received less material, will have a tendency to greater displacement than the other side. If thus the cylinder 12 is loaded more at its right side than at its left side viewed in the plane of FIG. 4, the plunger 136 will immediately meet a strong counter-pressure while the plunger 134 will have a tendency to displace the cylinder, so as to tend to cause an inclination thereof. Such inclination must, however, be counter-acted inter alia because the sealing between the shield plates 70 and the cylinder would be impaired.

As illustrated in FIG. 4 an adjusting valve 146a is provided. The valve has a body generally denoted by 148 with portions adapted to seal with sliding fit against cyli-ndric faces provided in the valve house and other portions having a minor diameter and separating the firstmentioned body portions from one another. The internal face of the valve casing also has alternating portions with larger and minor diameter. From a sump 150 oil is fed by a pump 152 under constant pressure firstly through a conduit 153 to a chamber 154 inthe valve and secondly through a conduit 156 with branch conduits 158 and 160 to the pressure chambers of two servo- motors 162 and 164, respectively. Within said servo- motors pistons 166 and 168 are operative to actuate the bearings 20 and 21, respectively, but in a direction opposite to the direction of actuation by the plungers 134 and 136. Since the pistons 166, 168 have a smaller diameter than the plungers 134, 136 the force by which the first-mentioned pistons actuate the cylinder 12 is less than the force exerted by the last-mentioned plungers as long as both the pistons and the plungers are subjected to the same specific oil pressure. Laterally of the central chamber 154 the valve casing is formed with chambers 170, 172, 174 and 176, which all are in connection with a conduit system 178, 180 which in turn is in open communication with the sump 150 for which reason no pressure can be built up in said chambers. A spring member 182 tends to push the body 148 to the left in the plane of FIG. 4. A prolongation 184 of the body 148 projects from the casing of the valve and supports one end of a lever arm 186 mounted pivotally rotatable about a journal 188 formed on a bar 190. The other end of said lever arm 186 is articulated with one end of a bar 194, the other end of which is inserted into the block 65 of the bearing 21. Another lever arm 196 is pivotably mounted in the stationary point 198 and by its one end articulated with the bar 190 and by its other end with a bar 200 extending to the block 64 of the other bearing 20.

In the position of the body 148 illustrated in FIG. 4 pressure fluid such as oil is supplied through the two conduits 140 and 142 under full pressure with which pressure thus the two plungers 134 and 136 uniformly actuate the cylinder 12 and which pressure may be of an order of magnitude of 50 tons in both servo-motors. If, however, for any reason the supply of fibrous substance to the right side of the cylinder 12 becomes less than the supply to the left side, the plunger 136 will meet less resistance and consequently displace the block 65 over a larger distance than the plunger 134 displaces the other block 64. The cylinder 12 will thus take an inclined position. This will, however, result in the fact that the bar 194 moves upwards and the lever arm 186 is turned counter-clockwise about the bearing point 188 and the body 148 is drawn towards the left viewed in the plane of FIG. 4. By this movement that part of the chamber 154 which communicates with the conduit 142 will be throttled and possibly totally sealed from the inlet 153 and in a corresponding degree connected with the pressureless drain 180. The force produced by the counter acting small servo-motor piston 168 will now become dominating and cause the block 65 to be pushed back and the interspace 69 readjusted to uniform width. If on the other hand the plunger 134 tends to displace the left block 64 so as to cause an inclined position of the cylinder 12, the arm 200 is brought automatically to move upwards and the lever arm 196 to turn in a clock-wise direction whereby the bar 190 is pushed to the right and entrains the lever arm 186 which is prevented by the bar 194 from rotation about the tap 188. As a consequence the body 148 will be forced to the right and the conduit 140 will now be opened to partly or completely reduced pressure, which allows the little piston 166 to push the block 64 back and thereby to eliminate the tendency of imparting an inclination to the cylinder 12.

Due to the feature that the roller 12 is displaceable in the horizontal plane in accordance with the description given hereinbefore and that the nip 38 is angularly displaced upwardly the further advantage is obtained that a larger pressure component is obtained than would be available if the nip would coincide with the plane of attack of the pressure. Since the driving sprocket is located below the bearings 20, 21 the cylinder 12 is capable of performing its displacement movements in the horizontal direction without any disturbing influence on the transfer of the driving force through the chain 58. The sprocket 60 will only swing over a minor angle in both directions from a central position which displacement is tolerable without any disadvantage.

The embodiment according to FIG. 5 differs from the preceding one substantially by the feature that the central bore 122 houses a stationary slide 202 having substantially semi-spherical cross-section. The bore 122 is preferably formed in a shaft 204 rigidly connected with the hub of the cylinder 12. Provided in the rear parts of the pockets 112 seen in the direction of rotation are channels or tubes 206 extending outwardly towards the screen 104 and communicating by means of channels 208 with the interior of the bore 122 when in a position directly in front of the interspace 69 and thus uncovered by the slide 202. The expelled liquid is carried away through the tubes 206 possibly by means of a vacuum produced in the'bore 122. When a channel 208 during the rotation is covered by the slide 202, the channel is closed and at the same time the outer opening of the tube 206 arrives at or adjacent the nip 38. The pockets 112 communicate through channels 210, 212 formed in the hub of the cylinder 12 and the shaft 204, respectively, with the interior of the slide 202 when the pockets pass through the upper part of the press where the removal of the compressed solid material is effected. It is obvious that the channels 208 and the channels 210, 212 are axially displaced in relationship to one another.

It may happen that solid material particles remaining in the apertures of the screen may act as bars for the passage of the liquid. In order to counter-act this effect a cleaning may be accomplished by conducting a gas stream, preferably air under pressure or steam, through the holes 96 when these move past the nip and before they have passed the horizontal plane. The space between the sleeve 86 and the outer wall of the drum should in such a structure be provided with partition walls subdividing said space into separate pockets, seen in the axial direction. Similar means may be provided for cleaning of the holes in the screen of the inner cylinder. In this case the pressure medium is introduced through a slide provided in the central bore of the inner cylinder which may resemble the member 202 though this latter has two passages.

While several embodiments of the invention have 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:

l. A press for separating material suspended in a liquid and which material is of a fibrous nature, comprising a pair of drum-like press members, one of which is disposed within the other land between which the suspens-ion is introduced, means for rotating said press members, said press members being on horizontal axes, with one of the press members being arranged eccentrically within the other to thereby provide spacing of crescent formation between them, said spacing at its narrowest point providing for a material-compressing nip, the two press members having foraminous portions through which separation of the liquid takes place, and hydraulically-operated servomotors located on opposite sides of the inner press member for urging the inner press member toward the outer press member with a force having a radial direction tending to be exerted below the point where the spacing between the press members is narrowest, the inner press member being radially displaceable relative to the outer press member in a horizontal direction in order to adjust the size of the nip in the spacing between them, bearings at each side of the inner .press member, and two additional hydraulicallyoperated servo motors acting in opposition to the firstmentioned servo motors to obtain a nip between the press members of the same Width for the length of the press members, said additional motors being arranged at the sides of the inner press member to individually actuate said bearings, the first-mentioned motors being of a larger capacity than the last-mentioned additional motors.

2. A press constructed according to claim 1 and characterised by the fact that control members are provided to co-operate with the inner press member in a manner to distribute the pressure in the axial extension of space between the press members so that the one of the firstmentioned servo motors which displaces its end of the inner press member more than the other is partly or totally unloaded.

3. A press constructed according to claim 1 and characterised by the fact that the inner press member has the shape of a cylinder whose outer periphery is covered by a fonaminous member which is internally axially sub-divided into a plurality of individually separated pockets, a center duct in the inner press member and the pockets being in communication with said duct.

4. A press constructed according to claim 3, and characterised by the fact that the outer press member consists of a drum, the inner side of which is covered with a screen member outside of which are arranged mutually communicating channels, a jacket extending around the outer drum and provided with reinforcing flanges, and the channels being arranged in said jacket.

References Cited in the file of this patent UNITED STATES PATENTS 2,374,046 Stocom Apr. 17, 1945 2,682,832 Lohre et a1. July 6, 1954 2,715,871 Dosne et a1 Aug. 23, 1955 2,764,869 Scherr Oct. 2, 1956 2,795,184 Graham June 11, 1957 2,978,976 Hazel-ton et al Apr. 11, 1961 3,000,294 Lowe et a1. Sept. 19, 1961 FOREIGN PATENTS 217,919 Australia Oct. 8, 1958

Claims (1)

1. A PRESS FOR SEPARATING MATERIAL SUSPENDED IN A LIQUID AND WHICH MATERIAL IS OF A FIBROUS NATURE, COMPRISING A PAIR OF DRUM-LIKE PRESS MEMBERS, ONE OF WHICH IS DISPOSED WITHIN THE OTHER AND BETWEEN WHICH THE SUSPENSION IS INTRODUCED, MEANS FOR ROTATING SAID PRESS MEMBERS, SAID PRESS MEMBERS BEING ON HORIZONTAL AXES, WITH ONE OF THE PRESS MEMBERS BEING ARRANGED ECCENTRICALLY WITHIN THE OTHER TO THEREBY PROVIDE SPACING OF CRESCENT FORMATION BETWEEN THEM, SAID SPACING AT ITS NARROWEST POINT PROVIDING FOR A MATERIAL-COMPRESSING NIP, THE TWO PRESS MEMBERS HAVING FORAMINOUS PORTIONS THROUGH WHICH SEPARATION OF THE LIQUID TAKES PLACE, AND HYDRAULICALLY-OPERATED SERVOMOTORS LOCATED ON OPPOSITE SIDES OF THE INNER PRESS MEMBER FOR URGING THE INNER PRESS MEMBER TOWARD THE OUTER PRESS MEMBER WITH A FORCE HAVING A RADIAL DIRECTION TENDING TO BE EXERTED BELOW THE POINT WHERE THE SPACING BETWEEN THE PRESS MEMBERS

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