CA1063523A - Apparatus for continuous separation of a suspension liquid from a fibrous suspension - Google Patents
Apparatus for continuous separation of a suspension liquid from a fibrous suspensionInfo
- Publication number
- CA1063523A CA1063523A CA216,129A CA216129A CA1063523A CA 1063523 A CA1063523 A CA 1063523A CA 216129 A CA216129 A CA 216129A CA 1063523 A CA1063523 A CA 1063523A
- Authority
- CA
- Canada
- Prior art keywords
- container
- receiving space
- filter element
- suspension
- filtrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/06—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums
- B01D33/073—Filters with filtering elements which move during the filtering operation with rotary cylindrical filtering surfaces, e.g. hollow drums arranged for inward flow filtration
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D33/00—Filters with filtering elements which move during the filtering operation
- B01D33/70—Filters with filtering elements which move during the filtering operation having feed or discharge devices
- B01D33/74—Filters with filtering elements which move during the filtering operation having feed or discharge devices for discharging filtrate
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Paper (AREA)
- Golf Clubs (AREA)
- Forging (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Filtration Of Liquid (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Apparatus for separating liquid from a fibrous suspension comprises a hollow container having an inlet and an outlet. A hollow filter element enclosing a filtrate-receiving space is rotatably mounted in the container such that an annular suspension-receiving space is defined between the walls of the filter element and the container. A discharge mechanism permits liquid filtrate to be discharged from the filtrate-receiving space at a rate sufficient to reduce the pressure in the space relative to the pressure in the suspension-receiving space so that liquid in the fibrous suspension flows through the filter element into the filtrate-receiving space, leaving a concentrated fibrous suspension in the annular space surrounding the filter element. The annular suspension-receiving space communicates with the inlet and the outlet of the con-tainer and has a radial width that diminishes from a point adja-cent the inlet circumferentially about the container toward the outlet. The radial width of the suspension receiving space abruptly increases adjacent the outlet of the container so that the pressure in the portion of the suspension-receiving space adjacent the outlet is reduced relative to the pressure in the filtrate-receiving space. The pressure differential causes a back flow of filtrate through the filter element to wash fibers from the surface of the element and facilitate the discharge of the concentrated suspension from the container.
Apparatus for separating liquid from a fibrous suspension comprises a hollow container having an inlet and an outlet. A hollow filter element enclosing a filtrate-receiving space is rotatably mounted in the container such that an annular suspension-receiving space is defined between the walls of the filter element and the container. A discharge mechanism permits liquid filtrate to be discharged from the filtrate-receiving space at a rate sufficient to reduce the pressure in the space relative to the pressure in the suspension-receiving space so that liquid in the fibrous suspension flows through the filter element into the filtrate-receiving space, leaving a concentrated fibrous suspension in the annular space surrounding the filter element. The annular suspension-receiving space communicates with the inlet and the outlet of the con-tainer and has a radial width that diminishes from a point adja-cent the inlet circumferentially about the container toward the outlet. The radial width of the suspension receiving space abruptly increases adjacent the outlet of the container so that the pressure in the portion of the suspension-receiving space adjacent the outlet is reduced relative to the pressure in the filtrate-receiving space. The pressure differential causes a back flow of filtrate through the filter element to wash fibers from the surface of the element and facilitate the discharge of the concentrated suspension from the container.
Description
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BACKGROUND OF THE INVENTION
In conjunction with the various stages in the pro-duction of wood pulp, such as washing, screening, bleaching, storage and drying, it is necessary to separate the liquid from a fibrous suspension in a dewatering or thickening step.
A thickener or pulp filter is most commonly used for the de-watering step, but centrifuges, presses and screw thickeners are also employed. Each of the pieces of conventional apparatus mentioned above is open so that the fibrous suspension and/or liquid filtrate is in contact with the atmosphere. The aeration resulting from contact with the atmosphere often cause problems in subsequent stages of the pulp production process and, accordingly, closed thickeners of various kinds have been proposed. A typical closed thickener is described and illustrated in Swedish Patent No. 347,779 and in corre-sponding British patent No. 1,211,765. To date, however, none of the closed thickeners that have been proposed has been utilized commercially in the pulp and paper industry since the proposed thickeners do not operate satisfactorily and ;~
; 20 have low capacities in relation to power consumption and ; production costs.
SUMMARY OF THE INVENTION
The present invention is directed to a method and apparatus for continuously separating liquid from a fibrous suspension in a closed system incorporating a filter element.
The inventive method and apparatus have a high efficiency per unit area of filtering element used so as to eliminate, or at least considerably reduce, the disadvantages arising from employing previously proposed separating techniques and ; 30 apparatus.
One major problem that the invention solves is how to remove fibers collected on the surface of a filtering ele-
BACKGROUND OF THE INVENTION
In conjunction with the various stages in the pro-duction of wood pulp, such as washing, screening, bleaching, storage and drying, it is necessary to separate the liquid from a fibrous suspension in a dewatering or thickening step.
A thickener or pulp filter is most commonly used for the de-watering step, but centrifuges, presses and screw thickeners are also employed. Each of the pieces of conventional apparatus mentioned above is open so that the fibrous suspension and/or liquid filtrate is in contact with the atmosphere. The aeration resulting from contact with the atmosphere often cause problems in subsequent stages of the pulp production process and, accordingly, closed thickeners of various kinds have been proposed. A typical closed thickener is described and illustrated in Swedish Patent No. 347,779 and in corre-sponding British patent No. 1,211,765. To date, however, none of the closed thickeners that have been proposed has been utilized commercially in the pulp and paper industry since the proposed thickeners do not operate satisfactorily and ;~
; 20 have low capacities in relation to power consumption and ; production costs.
SUMMARY OF THE INVENTION
The present invention is directed to a method and apparatus for continuously separating liquid from a fibrous suspension in a closed system incorporating a filter element.
The inventive method and apparatus have a high efficiency per unit area of filtering element used so as to eliminate, or at least considerably reduce, the disadvantages arising from employing previously proposed separating techniques and ; 30 apparatus.
One major problem that the invention solves is how to remove fibers collected on the surface of a filtering ele-
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ment so that the fib~rs can be discharged from the separating apparatus. According to the invention, a reversal of filtrate flow through the filtering element is effected continuously adjacent the fib~ous suspension outlet of the separating ap-paratus so that fibers, and any other particles that may have ; fastened in the openings of the filter element during filtering, are removed by a backwash of a portion of the filtrate removed from the suspension. This reverse flow is achieved by con-trolling hydrostatic pressures of the incoming fibrous sus-pension, the outflowing concentrated fibrous suspension, and the outflowing liquid filtrate, and by designing the flow path : for the fibrous suspension to provide a suitable rate of flow of the suspension, and thus a suitable hydrodynamic pressure along the filter element.
In general terms, the present invention provides an apparatus for the continuous separation of liquid from a ,, ~ fi~rous suspension comprising: a hollow generally cylindrical container; means defining an inlet for the container extending the full length of the container; means defining an outlet for the container extending the full length of the container; a hollow, cylindrical filter element having end walls that are impermeable to liquids and a side wall that is permeable to liquids and is adapted to retain fibers on a radially outer surface of the side wall, the filter element enclosing a filtrate-receiving space and being rotatably mounted in the container such that an annular suspension-receiving space is defined between walls of the filter elementand the container, the suspension-receiving space communicating with the outlet and the inlet of the container and diminishing in radial width from -a point adjacent the inlet circumferentially about the container toward the outlet; means for rotating the filter element to move the side wall thereof in a direction from the inlet to 1063~
the outlet of the container at a speed coinciding with the rate of flow of a fibrous suspension through the suspension-receiving space; a partition member having a first face and a second face and being arranged between the inlet and the outlet of the container such that the first face and the second face are generally coincident with said inlet and said outlet respectively said partition member extending along the full length of the container from a surface of the container to a radially outer surface of the filter element; discharge means for discharging liquid from the filtrate-receiving space at a rate sufficient to reduce pressure in the filtrate-receiving space relative to pressure in the suspension-receiving space such that liquid in the fibrous suspension flows through the filter element into the filtrate-receiving space, leaving a concentrated fibrous suspension in the suspension-receiving space and a layer of fibers retained on the radially outer surface of the filter element; a fiber separation space formed by an abrupt increase in the radial width of the suspension-receiving space adjacent the outlet of the container so that pressure in the fiber separation space is reduced relative to the pressure in the filtrate-receiving space, the pressure differential causing a portion of filtrate in the filtrate-receiving space to flow back through the filter element into the fiber separation space to loosen retained fibers on the radially outer surface of the side wall of the filter element and facilitate discharge of concentrated fibrous suspension from the container; and means extending along the full length of the container for controlling the increase in the radial width of the suspension-receiving space adjacent the outlet of the container, the controlling means including a flexible plate ~-: member attached at one end to a radially inner surface of the container and extending both radially inwardly and circumfer-:,.
. ' . . : , .- ., .: , 1~)6;~5'~3 entially of the container thus gradually to converge toward the filter element in the direction of movement of the side wall thereof as the filter element rotates and thereby to reduce the radial width of the suspension-receiving space, the other end of the plate member being free for movement radially to-ward and away from the filter element, and means for adjusting the position of the free end of the plate member in relation to the filter element.
In another aspect of the present invention, an apparatus is provided for the continuous separation of liquid :
from a fibrous suspension comprising: a hollow, generally cylindrical container; means defining an inlet for the con-tainer extending the full length of the container; means de-fining an outlet for the container extending the full length of the container; a hollow, cylindrical filter element having end walls that are impermeable to liquids and a side wall that is permeable to liquids and is adapted to retain fibers on its surface, the filter element enclosing a filtrate-receiving space and being rotatably mounted in the container such that an annular suspension-receiving space is defined between walls of the filter element and the container; a partition member having a first face and a second face and being arranged be-tween the inlet and the outlet of the container such that the -first face and the second face are generally coincident with said inlet and said outlet respectively, said partition member extending along the full length of the container from a sur-face of the container to a radially outer surface of the filter element; discharge means for discharging liquid from the filtrate receiving-space at a rate sufficient to reduce pres-sure in the filtrate-receiving space relative to pressure in the suspension receiving space such that liquid in the suspension flows through the filter element into the filtrate-.
, receiving space, leaving a concentrated fibrous suspension in the suspension-receiving space, the suspension-receiving space communicating with the inlet and the outlet of the container and diminishing in radial width from a point adjacent the in-let circumferentially about the container toward the outlet, ~ -~
the radial width of the suspension-receiving space abruptly increasing adjacent the outlet of the container so that pres-sure in a portion of the suspension-receiving space adjacent the outlet is reduced relative to the pressure in the filtrate-..
receiving space, thereby facilitating charge of the concentrated fibrous suspension from the container.
The radially inward edge of the partition member preferably defines a doctor blade that contacts the radially outer surface of the filter element. In another preferred embodiment, the appara'tus comprises means located within the filter element adjacent the inlet of the conta~ner for pro-ducing a suction at the surface of the filter element, in addition to the pressure reduction produced by the discharge means, so that a layer of fibers is immediately deposited on a radially outer surface of the filter element. According to a still further preferred embodiment, the apparatus com-prising means located within the filter element adjacent the outlet of the container~and the fiber-retaining surface of the filter element fo~r directing a blast ~f fluid radially out-wardly toward and ~hrough said surface of the,filter element.
The outlet is preferably arranged substantially adjacent the inlet. J
According to a still further preferred embodiment, the plate member includes, adjacent the Eree end, a U-shaped channel opening toward the filter element thus initially to provide a relatively small increase in the width of the sus-pension-receiving space, the free end of the plate member ,, , .
curving radially inwardly toward the filter elementand then outwardly away from the filter element thus finally to pro-vide a very rapid increase in the width of the suspension-receiving space.
The apparatus also provides space for adding devices -that might be necessary in certain types of operation. For example, when filtering suspensions having a pronounced dirtying effect on the filter element, a device for directing a stream of high pressure water against the wall of the filter element can be installed within the element to supplement the cleaning effected by the filtrate backwash. Similarly, I if filtrate of high purity is required, the capacity of the ¦ filter element to separate smaller fibers and particles from , the filtrate can be increased by causing a thin layer of fibers to be deposited on the filter element immediately adjacent the inlet to the apparatus. Such a deposit can be produced by a supplemental suction mechanism mounted within the filter element adjacent the inlet to the apparatus.
Filtrate collected by the suction mechanism is removed from the apparatus separately from the normal filtrate.
, BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention, refer-ence may be made to the following description of two exem-plary embodiments, taken in conjuction with the figures of the accompanying drawings, in which:
Fig. 1 is a side sectional view of apparatus accord-ing to the invention, taken along view line 1-1 of Fig. 2;
Fig. 2 is a transverse sectional view taken along view line 2-2 of Fig. l;
Fig. 3 is a portion of Fig. 2 on an enlarged scale;
and Fig. 4 is a view similar to Fig. 3, showing an ....
106~5'~
alternate embodiment of part of the apparatus of Fig. 3.
DESCRIPTION OF EMBODIMENTS :~ :
Fig. 1 of the drawings illustrates apparatus, according to the invention, which includes an upright, rotat-able, cylindrical drum, generally designed 11. The drum 11 includes an annular side wall 13 fabricated of perforated metal plate, or other material easily penetrated by liquids, covered with a fine mesh filter cloth that is also permeable to liquids but will retain fibers and other particles found in a wood pulp suspension. Finely perforated sheet metal may be used in place of the filter cloth. The upper and lower ends of the drum 11 are closed with circular end closures 15 and 17, respectively, which, together with the annular side wall 13, define a space 19 within the drum to receive filtrate passing through the side wall.
The drum 11 is mounted within a generally cylindrical vessel or container 25 that is supported on an appropriate surface by a pair of feet 81. The container 25 has an annular side wall 27 and lower and upper end walls or closures, 31 and 35, respectively. The drum 11 is rotatably mounted in the container 25 on a pivot 21 journaled in a bearing 29 held in the lower end closure 31 of the container. At the upper end of the drum 11, a connecting tube 23 extends through the upper end wall 35 of the container 25 and also acts as a pivot for the drum. Sealing element 33 prevents the escape of liquid from the container 25 around the connecting tube 23.
As is best shown in Fig. 2, the filter drum 11 is positioned within the container 25 so that the side walls 13 and 27 of the drum and the container, respectively, define an annular space 39 surrounding the drum. The radial width of the space 39 is greatest adjacent an inlet port 41 in the con-tainer 25 and decreases from the inlet circumferentially , : , ' ~ .: . ~ . ..
106;~5'~3 around the container toward an outlet port 51. Immediately adjacent the outlet port 51, the annular space 39, which generally defines a suspension-receiving and liquid-separation space, abruptly increases in radial width to define a fiber ; separation space 43. The change in radial width can be con-trolled by adjustment of a restrictor plate 45, shown in de-tail in Fig. 3, which is affixed at one end to the radially inner wall surface of the container 25. The plate 45 extends in the direction of rotation of the drum 11 both circumfer-entially of the container 25 and radial inwardly of the con-tainer. An adjustable bolt 47 is threaded through the side wall 27 of the container 25 and contacts the free end of the restrictor plate 45. The bolt 47 acts against the spring biasing action of the plate 45 so as to control the radial distance between the end of the restrictor plate and the radially outer surface of the filter drum 11.
The inlet port 41 extends along the entire length or height of the container 25 and has an inlet fitting 49 for connection to an appropriate supply line (not shown).
Similarly, the discharge port 51 extends for the entire length or height of the container 25 and has an outlet fitting 53 that can be connected to a discharge conduit (not shown).
The rotatable drum 11 is driven by a motor (not shown) through V belts 55 that extend around a pulley 57 fitted on the connecting tube 23. A fixed position elbow 59 having the same outer diameter as the connecting tube 23 is connected to the tube by an overlapping bearing and sealing member 61.
Within the drum 11 adjacent the outlet port 51, an elongated, high pressure water box 63 is disposed against the inner surface of the side wall 13 of the drum. The upper end of the box 63 is supported and maintained in position by a supply line 69 connected to the box. The lower end of the _ g _ 1()635'~3 63 is supported by an arm 71 rotatably mounted on the pivot 21. Line 69 extends first radially through the drum 11 and ~
the container 25 and then axially alongside the connecting ~ i tube 23 through an outlet fitting 73 on the elbow 59. The position of the high pressure water box 63 relative to the outer container can be adjusted by rotating the supply line 69. Particular apparatus for setting and locating the water box 63 are not shown in the drawings for clarity.
setween the outlet port 51 and the inlet port 41, in the direction of rotation of the drum 11, is a partition member 67 that extends from a wall of the container 25 toward the radially outer surface of the filter drum 11. At the radially inward end of the partition member 67 is a doctor blade 65 that contacts the outer drum surface. Immediately beyond the doctor blade 65 and adjacent the inlet port 41 is a suction box 75 mounted inside the drum adjacent the inner surface of the drum wall 13. The suction box 75 is supported by an outlet pipe 77 and by a support arm 79 at-tached to the lower end of the suction box. The pipe 77 passes through the upper ends 15 and 35 of the drum 11 and the container 25, respectively, alongside the pipe 69. -i In operation, the drum 11 is rotated in the direc-tion of the arrow in Fig. 2 and fibrous pulp suspension is supplied continuously through the inlet connecting fitting 49 and the inlet port 41 into the annular space 39 at a relatively low positive pressure, i.e. about 5 to 20 M W.G. (meters water, gauge). Higher pressures can be used but increased pressure will require stronger and more expensive apparatus. The liquid in the suspension permeates through the side wall 13 of the drum 11 into the filtrate receiving space 19, which is kept filled with liquid and is at a pressure lower than the pressure in the annular space 39. As the suspension flows il)635Z3 .
along the annular space 39 around the container 25, in the direction of rotation of the drum 11, the quantity of liquid in the suspension diminishes. Liquid filtrate separated from the suspension and passing into the space 19 is drawn off through the connecting tube 23 at a rate sufficient to main-tain a substantially constant pressure differential between the annular space 39 and the filtrate receiving space 19.
The pressure differential is maintained through the use of conventional control elements which control the flow quantity through the cannecting tube 23 and which are not shown in the drawings for clarity.
As the radial width of the space 39 decreases, a layer of fibers is formed on the outer surface of the wall 13 of drum 11, which layer increases in thickness as the drum rotates and the suspension flows around the space 39. As the concentrated suspension flows past the free end of the ; restrictor plate 45, the increased velocity and ejector action produced by the sudden increase in the radial width of the annular space 39 at the fiber separation space 43 reduce the pressure in the fiber separation space 43 below the pressure within the drum 11. The pressure differential causes a small part of the filtrate in the space 19 to flow through the wall 13 of the drum 11 to clean the pores in the drum wall and to loosen the layer of fibers from the outer surface of the drum wall 13. The separation of the layer of fibers from the outer surface of the wall 13 of the drum 11 is insured by the plastic doctor blade 65. (Alternatively, a water doctor may be used.) After being loosened from the drum wall 13, the layer of fibers is partially diluted by filtrate flowing from the filtrate-receiving space 19 so that the fibers can be drawn out through the outlet port 51 together with the con-centrated and thickened fibrous suspension.
..
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- In separating liquids from fibrous suspensions con-taining sludge or fillers, such as china clay or dyestuff, the high pressure water box 63 can supplement the ejector action cleaning of the filter drum 11. The water box 63 directs a blast of clean water at the drum wall 13, when necessary, at a pressure higher than the pressure in the fiber separation space 43.
In order to obtain a liquid filtrate of high purity in the filtrate receiving space 19, it may be desirable to fix a thin layer of fibers on the surface of the wall 13 of the drum 11 as soon as possible during the thickening operation.
By applying suction through the suction box 75, a thin layer of fibers can be quickly formed along the length or height of the wall 13. Since filtrate collected in the suction box 75 will contain impurities of a kind that can penetrate the filter cloth, the filtrate collected in the box is returned , through the outlet pipe 77 to the fibrous suspension being supplied to the apparatus for liquid separation. By suitable control of the outflow through the outlet pipe 77, the flow of liquid through the drum wall 13 into the suction box 75 can be restricted to a velocity that is not too great and that avoids the possibility of fibers embedding themselves in the filter cloth.
The consistency of the discharged concentrated , fibrous suspension can be adjusted within a particularly wide 7 range by changing the radial distance or width of the annular space 39. Such adjustment is achieved by controlling the spacing of the restrictor plate 45 from the outer surface of the drum 11 through the screw or bolt 47. The rotational speed 30 of the drum 11 and the quantity of filtrate flowing from the filtrate receiving space 19 should be adjusted simultaneously with the radial width of the space 39. Optimum efficiency '' " " , .
. - . : . : . :
iO6~5'~3 will be obtained when the peripheral speed of the drum ll coincides with the rate of flow of fibrous suspension through the liquid separation space 39 and when the optimum pressure difference for the particular fibrous suspension is maintained between the liquid-separation space 39 and filtrate-receiving space l9.
Instead of controlling the radial width of the an-nular liquid-separation space 39 by a screw or bolt device 47, the radial width can be controlled by pneumatically or hydrau-lically loading the restrictorplate 45 to a constant pressure, regardless of the quantity of fibrous suspension flowing through the liquid separation space 39. If the quantity of filtrate drawn off from the filtrate space l9 is kept constant, any variations in the consistency of the fibrous suspension supplied to the container 25 will be maintained in the con-centrated or thickened fibrous suspension discharged through the outlet port 51, provided the flow quantity is kept con-stant. The consistency of the discharged thickened suspension can be monitored conveniently by a conventional consistency controller and can be kept constant by regulating the quantity of filtrate drawn off from the filtrate space l9 by a con-ventional control valve controlled by the consistency control-ler. The control valve and the consistency controller are preferably fitted in the piping system and are not shown for clarity in the drawings.
Fig. 4 of the drawings shows an alternate embodiment of the invention and, more particularly, an alternate embodi-ment of the restrictor plate 45'. The embodiment of Fig. 4 is most effective when the layer of fibers on the drum wall 13 is relatively thin. The plate 45' is larger in the direc-tion of rotation of drum ll, relative to the embodiment of Fig. 3, and has, adjacent its free end, a rectangular step - 13 _ 635'~3 away from the outer surface of the drum to provide a rectan-gular channel 83. The end of the restrictor plate 45' curves radially inwardly toward the drum 11 and then outwardly away from the drum to define a guide plate 85. The plate 45' thus provides an initial relatively small increase in the width of the annular space 39 and then a very rapid increase at the guide plate 85. The ejector action of the separating apparatus is more pronounced with a restrictor plate 45' according to the embodiment of Fig. 4. A relatively high peripheral speed of the drum 11 is required, however, as compared to the restrictor plate 45 of Figs. 1-3, in order for the apparatus of Fig. 4 to operate properly. Thus, the separating apparatus of Fig. 4 also requires a higher rate of flow of fibrous sus-pension through the annular space 39.
The effectiveness of the inventive method and apparatus is illustrated by the following example:
EXAMPLE
A feedstock of unbleached softwood kraft pulp having a 1.2% consistency was introduced into apparatus con-structed according to the invention having a filter drum 1500 mm in diameter. The radial width of the suspension-receiving space varied from 80 mm adjacent the inlet of the apparatus to 10 mm at the restrictor plate. The filter drum was rotated at a peripheral speed of 20 meters per second, requiring power consumption of 5 to 10 kilowatts. The dif-ference between the pressure at the inlet fitting 49 and the fixed discharge elbow 59 was maintained at 6 meters of water. The consistency of the thickened pulp flowing from the outlet of the apparatus was 3.6%.
It will be understood that the embodiments described above are merely exemplary and that persons skilled in the art may make many variations and modifications without departing ~, - ~ i, ' : ' :, :
, 1(~635Z3 from the spirit and scope of the invention. All such mod-ifications and variations are intended to be within the scope of the invention as defined in the appended claims.
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ment so that the fib~rs can be discharged from the separating apparatus. According to the invention, a reversal of filtrate flow through the filtering element is effected continuously adjacent the fib~ous suspension outlet of the separating ap-paratus so that fibers, and any other particles that may have ; fastened in the openings of the filter element during filtering, are removed by a backwash of a portion of the filtrate removed from the suspension. This reverse flow is achieved by con-trolling hydrostatic pressures of the incoming fibrous sus-pension, the outflowing concentrated fibrous suspension, and the outflowing liquid filtrate, and by designing the flow path : for the fibrous suspension to provide a suitable rate of flow of the suspension, and thus a suitable hydrodynamic pressure along the filter element.
In general terms, the present invention provides an apparatus for the continuous separation of liquid from a ,, ~ fi~rous suspension comprising: a hollow generally cylindrical container; means defining an inlet for the container extending the full length of the container; means defining an outlet for the container extending the full length of the container; a hollow, cylindrical filter element having end walls that are impermeable to liquids and a side wall that is permeable to liquids and is adapted to retain fibers on a radially outer surface of the side wall, the filter element enclosing a filtrate-receiving space and being rotatably mounted in the container such that an annular suspension-receiving space is defined between walls of the filter elementand the container, the suspension-receiving space communicating with the outlet and the inlet of the container and diminishing in radial width from -a point adjacent the inlet circumferentially about the container toward the outlet; means for rotating the filter element to move the side wall thereof in a direction from the inlet to 1063~
the outlet of the container at a speed coinciding with the rate of flow of a fibrous suspension through the suspension-receiving space; a partition member having a first face and a second face and being arranged between the inlet and the outlet of the container such that the first face and the second face are generally coincident with said inlet and said outlet respectively said partition member extending along the full length of the container from a surface of the container to a radially outer surface of the filter element; discharge means for discharging liquid from the filtrate-receiving space at a rate sufficient to reduce pressure in the filtrate-receiving space relative to pressure in the suspension-receiving space such that liquid in the fibrous suspension flows through the filter element into the filtrate-receiving space, leaving a concentrated fibrous suspension in the suspension-receiving space and a layer of fibers retained on the radially outer surface of the filter element; a fiber separation space formed by an abrupt increase in the radial width of the suspension-receiving space adjacent the outlet of the container so that pressure in the fiber separation space is reduced relative to the pressure in the filtrate-receiving space, the pressure differential causing a portion of filtrate in the filtrate-receiving space to flow back through the filter element into the fiber separation space to loosen retained fibers on the radially outer surface of the side wall of the filter element and facilitate discharge of concentrated fibrous suspension from the container; and means extending along the full length of the container for controlling the increase in the radial width of the suspension-receiving space adjacent the outlet of the container, the controlling means including a flexible plate ~-: member attached at one end to a radially inner surface of the container and extending both radially inwardly and circumfer-:,.
. ' . . : , .- ., .: , 1~)6;~5'~3 entially of the container thus gradually to converge toward the filter element in the direction of movement of the side wall thereof as the filter element rotates and thereby to reduce the radial width of the suspension-receiving space, the other end of the plate member being free for movement radially to-ward and away from the filter element, and means for adjusting the position of the free end of the plate member in relation to the filter element.
In another aspect of the present invention, an apparatus is provided for the continuous separation of liquid :
from a fibrous suspension comprising: a hollow, generally cylindrical container; means defining an inlet for the con-tainer extending the full length of the container; means de-fining an outlet for the container extending the full length of the container; a hollow, cylindrical filter element having end walls that are impermeable to liquids and a side wall that is permeable to liquids and is adapted to retain fibers on its surface, the filter element enclosing a filtrate-receiving space and being rotatably mounted in the container such that an annular suspension-receiving space is defined between walls of the filter element and the container; a partition member having a first face and a second face and being arranged be-tween the inlet and the outlet of the container such that the -first face and the second face are generally coincident with said inlet and said outlet respectively, said partition member extending along the full length of the container from a sur-face of the container to a radially outer surface of the filter element; discharge means for discharging liquid from the filtrate receiving-space at a rate sufficient to reduce pres-sure in the filtrate-receiving space relative to pressure in the suspension receiving space such that liquid in the suspension flows through the filter element into the filtrate-.
, receiving space, leaving a concentrated fibrous suspension in the suspension-receiving space, the suspension-receiving space communicating with the inlet and the outlet of the container and diminishing in radial width from a point adjacent the in-let circumferentially about the container toward the outlet, ~ -~
the radial width of the suspension-receiving space abruptly increasing adjacent the outlet of the container so that pres-sure in a portion of the suspension-receiving space adjacent the outlet is reduced relative to the pressure in the filtrate-..
receiving space, thereby facilitating charge of the concentrated fibrous suspension from the container.
The radially inward edge of the partition member preferably defines a doctor blade that contacts the radially outer surface of the filter element. In another preferred embodiment, the appara'tus comprises means located within the filter element adjacent the inlet of the conta~ner for pro-ducing a suction at the surface of the filter element, in addition to the pressure reduction produced by the discharge means, so that a layer of fibers is immediately deposited on a radially outer surface of the filter element. According to a still further preferred embodiment, the apparatus com-prising means located within the filter element adjacent the outlet of the container~and the fiber-retaining surface of the filter element fo~r directing a blast ~f fluid radially out-wardly toward and ~hrough said surface of the,filter element.
The outlet is preferably arranged substantially adjacent the inlet. J
According to a still further preferred embodiment, the plate member includes, adjacent the Eree end, a U-shaped channel opening toward the filter element thus initially to provide a relatively small increase in the width of the sus-pension-receiving space, the free end of the plate member ,, , .
curving radially inwardly toward the filter elementand then outwardly away from the filter element thus finally to pro-vide a very rapid increase in the width of the suspension-receiving space.
The apparatus also provides space for adding devices -that might be necessary in certain types of operation. For example, when filtering suspensions having a pronounced dirtying effect on the filter element, a device for directing a stream of high pressure water against the wall of the filter element can be installed within the element to supplement the cleaning effected by the filtrate backwash. Similarly, I if filtrate of high purity is required, the capacity of the ¦ filter element to separate smaller fibers and particles from , the filtrate can be increased by causing a thin layer of fibers to be deposited on the filter element immediately adjacent the inlet to the apparatus. Such a deposit can be produced by a supplemental suction mechanism mounted within the filter element adjacent the inlet to the apparatus.
Filtrate collected by the suction mechanism is removed from the apparatus separately from the normal filtrate.
, BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention, refer-ence may be made to the following description of two exem-plary embodiments, taken in conjuction with the figures of the accompanying drawings, in which:
Fig. 1 is a side sectional view of apparatus accord-ing to the invention, taken along view line 1-1 of Fig. 2;
Fig. 2 is a transverse sectional view taken along view line 2-2 of Fig. l;
Fig. 3 is a portion of Fig. 2 on an enlarged scale;
and Fig. 4 is a view similar to Fig. 3, showing an ....
106~5'~
alternate embodiment of part of the apparatus of Fig. 3.
DESCRIPTION OF EMBODIMENTS :~ :
Fig. 1 of the drawings illustrates apparatus, according to the invention, which includes an upright, rotat-able, cylindrical drum, generally designed 11. The drum 11 includes an annular side wall 13 fabricated of perforated metal plate, or other material easily penetrated by liquids, covered with a fine mesh filter cloth that is also permeable to liquids but will retain fibers and other particles found in a wood pulp suspension. Finely perforated sheet metal may be used in place of the filter cloth. The upper and lower ends of the drum 11 are closed with circular end closures 15 and 17, respectively, which, together with the annular side wall 13, define a space 19 within the drum to receive filtrate passing through the side wall.
The drum 11 is mounted within a generally cylindrical vessel or container 25 that is supported on an appropriate surface by a pair of feet 81. The container 25 has an annular side wall 27 and lower and upper end walls or closures, 31 and 35, respectively. The drum 11 is rotatably mounted in the container 25 on a pivot 21 journaled in a bearing 29 held in the lower end closure 31 of the container. At the upper end of the drum 11, a connecting tube 23 extends through the upper end wall 35 of the container 25 and also acts as a pivot for the drum. Sealing element 33 prevents the escape of liquid from the container 25 around the connecting tube 23.
As is best shown in Fig. 2, the filter drum 11 is positioned within the container 25 so that the side walls 13 and 27 of the drum and the container, respectively, define an annular space 39 surrounding the drum. The radial width of the space 39 is greatest adjacent an inlet port 41 in the con-tainer 25 and decreases from the inlet circumferentially , : , ' ~ .: . ~ . ..
106;~5'~3 around the container toward an outlet port 51. Immediately adjacent the outlet port 51, the annular space 39, which generally defines a suspension-receiving and liquid-separation space, abruptly increases in radial width to define a fiber ; separation space 43. The change in radial width can be con-trolled by adjustment of a restrictor plate 45, shown in de-tail in Fig. 3, which is affixed at one end to the radially inner wall surface of the container 25. The plate 45 extends in the direction of rotation of the drum 11 both circumfer-entially of the container 25 and radial inwardly of the con-tainer. An adjustable bolt 47 is threaded through the side wall 27 of the container 25 and contacts the free end of the restrictor plate 45. The bolt 47 acts against the spring biasing action of the plate 45 so as to control the radial distance between the end of the restrictor plate and the radially outer surface of the filter drum 11.
The inlet port 41 extends along the entire length or height of the container 25 and has an inlet fitting 49 for connection to an appropriate supply line (not shown).
Similarly, the discharge port 51 extends for the entire length or height of the container 25 and has an outlet fitting 53 that can be connected to a discharge conduit (not shown).
The rotatable drum 11 is driven by a motor (not shown) through V belts 55 that extend around a pulley 57 fitted on the connecting tube 23. A fixed position elbow 59 having the same outer diameter as the connecting tube 23 is connected to the tube by an overlapping bearing and sealing member 61.
Within the drum 11 adjacent the outlet port 51, an elongated, high pressure water box 63 is disposed against the inner surface of the side wall 13 of the drum. The upper end of the box 63 is supported and maintained in position by a supply line 69 connected to the box. The lower end of the _ g _ 1()635'~3 63 is supported by an arm 71 rotatably mounted on the pivot 21. Line 69 extends first radially through the drum 11 and ~
the container 25 and then axially alongside the connecting ~ i tube 23 through an outlet fitting 73 on the elbow 59. The position of the high pressure water box 63 relative to the outer container can be adjusted by rotating the supply line 69. Particular apparatus for setting and locating the water box 63 are not shown in the drawings for clarity.
setween the outlet port 51 and the inlet port 41, in the direction of rotation of the drum 11, is a partition member 67 that extends from a wall of the container 25 toward the radially outer surface of the filter drum 11. At the radially inward end of the partition member 67 is a doctor blade 65 that contacts the outer drum surface. Immediately beyond the doctor blade 65 and adjacent the inlet port 41 is a suction box 75 mounted inside the drum adjacent the inner surface of the drum wall 13. The suction box 75 is supported by an outlet pipe 77 and by a support arm 79 at-tached to the lower end of the suction box. The pipe 77 passes through the upper ends 15 and 35 of the drum 11 and the container 25, respectively, alongside the pipe 69. -i In operation, the drum 11 is rotated in the direc-tion of the arrow in Fig. 2 and fibrous pulp suspension is supplied continuously through the inlet connecting fitting 49 and the inlet port 41 into the annular space 39 at a relatively low positive pressure, i.e. about 5 to 20 M W.G. (meters water, gauge). Higher pressures can be used but increased pressure will require stronger and more expensive apparatus. The liquid in the suspension permeates through the side wall 13 of the drum 11 into the filtrate receiving space 19, which is kept filled with liquid and is at a pressure lower than the pressure in the annular space 39. As the suspension flows il)635Z3 .
along the annular space 39 around the container 25, in the direction of rotation of the drum 11, the quantity of liquid in the suspension diminishes. Liquid filtrate separated from the suspension and passing into the space 19 is drawn off through the connecting tube 23 at a rate sufficient to main-tain a substantially constant pressure differential between the annular space 39 and the filtrate receiving space 19.
The pressure differential is maintained through the use of conventional control elements which control the flow quantity through the cannecting tube 23 and which are not shown in the drawings for clarity.
As the radial width of the space 39 decreases, a layer of fibers is formed on the outer surface of the wall 13 of drum 11, which layer increases in thickness as the drum rotates and the suspension flows around the space 39. As the concentrated suspension flows past the free end of the ; restrictor plate 45, the increased velocity and ejector action produced by the sudden increase in the radial width of the annular space 39 at the fiber separation space 43 reduce the pressure in the fiber separation space 43 below the pressure within the drum 11. The pressure differential causes a small part of the filtrate in the space 19 to flow through the wall 13 of the drum 11 to clean the pores in the drum wall and to loosen the layer of fibers from the outer surface of the drum wall 13. The separation of the layer of fibers from the outer surface of the wall 13 of the drum 11 is insured by the plastic doctor blade 65. (Alternatively, a water doctor may be used.) After being loosened from the drum wall 13, the layer of fibers is partially diluted by filtrate flowing from the filtrate-receiving space 19 so that the fibers can be drawn out through the outlet port 51 together with the con-centrated and thickened fibrous suspension.
..
1()635,'~
- In separating liquids from fibrous suspensions con-taining sludge or fillers, such as china clay or dyestuff, the high pressure water box 63 can supplement the ejector action cleaning of the filter drum 11. The water box 63 directs a blast of clean water at the drum wall 13, when necessary, at a pressure higher than the pressure in the fiber separation space 43.
In order to obtain a liquid filtrate of high purity in the filtrate receiving space 19, it may be desirable to fix a thin layer of fibers on the surface of the wall 13 of the drum 11 as soon as possible during the thickening operation.
By applying suction through the suction box 75, a thin layer of fibers can be quickly formed along the length or height of the wall 13. Since filtrate collected in the suction box 75 will contain impurities of a kind that can penetrate the filter cloth, the filtrate collected in the box is returned , through the outlet pipe 77 to the fibrous suspension being supplied to the apparatus for liquid separation. By suitable control of the outflow through the outlet pipe 77, the flow of liquid through the drum wall 13 into the suction box 75 can be restricted to a velocity that is not too great and that avoids the possibility of fibers embedding themselves in the filter cloth.
The consistency of the discharged concentrated , fibrous suspension can be adjusted within a particularly wide 7 range by changing the radial distance or width of the annular space 39. Such adjustment is achieved by controlling the spacing of the restrictor plate 45 from the outer surface of the drum 11 through the screw or bolt 47. The rotational speed 30 of the drum 11 and the quantity of filtrate flowing from the filtrate receiving space 19 should be adjusted simultaneously with the radial width of the space 39. Optimum efficiency '' " " , .
. - . : . : . :
iO6~5'~3 will be obtained when the peripheral speed of the drum ll coincides with the rate of flow of fibrous suspension through the liquid separation space 39 and when the optimum pressure difference for the particular fibrous suspension is maintained between the liquid-separation space 39 and filtrate-receiving space l9.
Instead of controlling the radial width of the an-nular liquid-separation space 39 by a screw or bolt device 47, the radial width can be controlled by pneumatically or hydrau-lically loading the restrictorplate 45 to a constant pressure, regardless of the quantity of fibrous suspension flowing through the liquid separation space 39. If the quantity of filtrate drawn off from the filtrate space l9 is kept constant, any variations in the consistency of the fibrous suspension supplied to the container 25 will be maintained in the con-centrated or thickened fibrous suspension discharged through the outlet port 51, provided the flow quantity is kept con-stant. The consistency of the discharged thickened suspension can be monitored conveniently by a conventional consistency controller and can be kept constant by regulating the quantity of filtrate drawn off from the filtrate space l9 by a con-ventional control valve controlled by the consistency control-ler. The control valve and the consistency controller are preferably fitted in the piping system and are not shown for clarity in the drawings.
Fig. 4 of the drawings shows an alternate embodiment of the invention and, more particularly, an alternate embodi-ment of the restrictor plate 45'. The embodiment of Fig. 4 is most effective when the layer of fibers on the drum wall 13 is relatively thin. The plate 45' is larger in the direc-tion of rotation of drum ll, relative to the embodiment of Fig. 3, and has, adjacent its free end, a rectangular step - 13 _ 635'~3 away from the outer surface of the drum to provide a rectan-gular channel 83. The end of the restrictor plate 45' curves radially inwardly toward the drum 11 and then outwardly away from the drum to define a guide plate 85. The plate 45' thus provides an initial relatively small increase in the width of the annular space 39 and then a very rapid increase at the guide plate 85. The ejector action of the separating apparatus is more pronounced with a restrictor plate 45' according to the embodiment of Fig. 4. A relatively high peripheral speed of the drum 11 is required, however, as compared to the restrictor plate 45 of Figs. 1-3, in order for the apparatus of Fig. 4 to operate properly. Thus, the separating apparatus of Fig. 4 also requires a higher rate of flow of fibrous sus-pension through the annular space 39.
The effectiveness of the inventive method and apparatus is illustrated by the following example:
EXAMPLE
A feedstock of unbleached softwood kraft pulp having a 1.2% consistency was introduced into apparatus con-structed according to the invention having a filter drum 1500 mm in diameter. The radial width of the suspension-receiving space varied from 80 mm adjacent the inlet of the apparatus to 10 mm at the restrictor plate. The filter drum was rotated at a peripheral speed of 20 meters per second, requiring power consumption of 5 to 10 kilowatts. The dif-ference between the pressure at the inlet fitting 49 and the fixed discharge elbow 59 was maintained at 6 meters of water. The consistency of the thickened pulp flowing from the outlet of the apparatus was 3.6%.
It will be understood that the embodiments described above are merely exemplary and that persons skilled in the art may make many variations and modifications without departing ~, - ~ i, ' : ' :, :
, 1(~635Z3 from the spirit and scope of the invention. All such mod-ifications and variations are intended to be within the scope of the invention as defined in the appended claims.
. .
::
Claims (7)
1. An apparatus for the continuous separation of liquid from a fibrous suspension comprising:
(a) a hollow, generally cylindrical container;
(b) means defining an inlet for the container ex-tending the full length of the container;
(c) means defining an outlet for the container ex-tending the full length of the container;
(d) a hollow, cylindrical filter element having end walls that are impermeable to liquids and a side wall that is permeable to liquids and is adapted to retain fibers on a radially outer surface of the side wall, the filter element enclosing a filtrate-receiving space and being rotatably mounted in the container such that an annular suspension-receiving space is defined between walls of the filter element and the container, the suspension-receiving space communicating with the outlet and the inlet of the container and diminishing in radial width from a point adjacent the inlet circumferentially about the container toward the outlet;
(e) means for rotating the filter element to move the side wall thereof in a direction from the inlet to the outlet of the container at a speed coinciding with the rate of flow of a fibrous suspension through the suspension-receiving space;
(f) a partition member having a first face and a second face and being arranged between the inlet and the outlet of the container such that the first face and the second face are generally coincident with said inlet and said outlet respectively, said partition member extending along the full length of the container from a surface of the container to a radially outer surface of the filter element.
(g) discharge means for discharging liquid from the filtrate-receiving space at a rate sufficient to reduce pressure in the filtrate-receiving space relative to pressure in the suspension-receiving space such that liquid in the fibrous suspension flows through the filter element into the filtrate-receiving space, leaving a concentrated fibrous sus-pension in the suspension-receiving space and a layer of fibers retained on the radially outer surface of the filter element;
(h) a fiber separation space formed by an abrupt increase in the radial width of the suspension-receiving space adjacent the outlet of the container so that pressure in the fiber separation space is reduced relative to the pressure in the filtrate-receiving space, the pressure differential causing a portion of filtrate in the filtrate-receiving space to flow back through the filter element into the fiber separation space to loosen retained fibers on the radially outer surface of the side wall of the filter element and facilitate discharge of concentrated fibrous suspension from the container; and (i) means extending along the full length of the container for controlling the increase in the radial width of the suspension-receiving space adjacent the outlet of the container, the controlling means including a flexible plate member attached at one end to a radially inner surface of the container and extending both radially inwardly and circumfer-entially of the container thus gradually to converge toward the filter element in the direction of movement of the side wall thereof as the filter element rotates and thereby to reduce the radial width of the suspension-receiving space, the other end of the plate member being free for movement radially toward and away from the filter element, and means for ad-justing the position of the free end of the plate member in relation to the filter element.
(a) a hollow, generally cylindrical container;
(b) means defining an inlet for the container ex-tending the full length of the container;
(c) means defining an outlet for the container ex-tending the full length of the container;
(d) a hollow, cylindrical filter element having end walls that are impermeable to liquids and a side wall that is permeable to liquids and is adapted to retain fibers on a radially outer surface of the side wall, the filter element enclosing a filtrate-receiving space and being rotatably mounted in the container such that an annular suspension-receiving space is defined between walls of the filter element and the container, the suspension-receiving space communicating with the outlet and the inlet of the container and diminishing in radial width from a point adjacent the inlet circumferentially about the container toward the outlet;
(e) means for rotating the filter element to move the side wall thereof in a direction from the inlet to the outlet of the container at a speed coinciding with the rate of flow of a fibrous suspension through the suspension-receiving space;
(f) a partition member having a first face and a second face and being arranged between the inlet and the outlet of the container such that the first face and the second face are generally coincident with said inlet and said outlet respectively, said partition member extending along the full length of the container from a surface of the container to a radially outer surface of the filter element.
(g) discharge means for discharging liquid from the filtrate-receiving space at a rate sufficient to reduce pressure in the filtrate-receiving space relative to pressure in the suspension-receiving space such that liquid in the fibrous suspension flows through the filter element into the filtrate-receiving space, leaving a concentrated fibrous sus-pension in the suspension-receiving space and a layer of fibers retained on the radially outer surface of the filter element;
(h) a fiber separation space formed by an abrupt increase in the radial width of the suspension-receiving space adjacent the outlet of the container so that pressure in the fiber separation space is reduced relative to the pressure in the filtrate-receiving space, the pressure differential causing a portion of filtrate in the filtrate-receiving space to flow back through the filter element into the fiber separation space to loosen retained fibers on the radially outer surface of the side wall of the filter element and facilitate discharge of concentrated fibrous suspension from the container; and (i) means extending along the full length of the container for controlling the increase in the radial width of the suspension-receiving space adjacent the outlet of the container, the controlling means including a flexible plate member attached at one end to a radially inner surface of the container and extending both radially inwardly and circumfer-entially of the container thus gradually to converge toward the filter element in the direction of movement of the side wall thereof as the filter element rotates and thereby to reduce the radial width of the suspension-receiving space, the other end of the plate member being free for movement radially toward and away from the filter element, and means for ad-justing the position of the free end of the plate member in relation to the filter element.
2. Apparatus for the continuous separation of liquid from a fibrous suspension comprising:
(a) a hollow, generally cylindrical container;
(b) means defining an inlet for the container ex-tending the full length of the container;
(c) means defining an outlet for the container ex-tending the full length of the container;
(d) a hollow, cylindrical filter element having end walls that are impermeable to liquids and a side wall that is permeable to liquids and is adapted to retain fibers on its surface, the filter element enclosing a filtrate-receiving space and being rotatably mounted in the container such that an annular suspension-receiving space is defined between walls of the filter element and the container;
(e) a partition member having a first face and a second face and being arranged between the inlet and the out-let of the container such that the first face and the second face are generally coincident with said inlet and said out-let respectively, said partition member extending along the full length of the container from a surface of the container to a radially outer surface of the filter element;
(f) discharge means for discharging liquid from the filtrate receiving-space at a rate sufficient to reduce pressure in the filtrate-receiving space relative to pressure in the suspension-receiving space such that liquid in the suspension flows through the filter element into the filtrate-receiving space, leaving a concentrated fibrous suspension in the suspension-receiving space, the suspension-receiving space communicating with the inlet and the outlet of the container and diminishing in radial width from a point adjacent the inlet circumferentially about the container toward the outlet, the radial width of the sus-pension-receiving space abruptly increasing adjacent the out-let of the container so that pressure in a portion of the suspension-receiving space adjacent the outlet is reduced relative to the pressure in the filtrate-receiving space, thereby facilitating discharge of the concentrated fibrous suspension from the container.
(a) a hollow, generally cylindrical container;
(b) means defining an inlet for the container ex-tending the full length of the container;
(c) means defining an outlet for the container ex-tending the full length of the container;
(d) a hollow, cylindrical filter element having end walls that are impermeable to liquids and a side wall that is permeable to liquids and is adapted to retain fibers on its surface, the filter element enclosing a filtrate-receiving space and being rotatably mounted in the container such that an annular suspension-receiving space is defined between walls of the filter element and the container;
(e) a partition member having a first face and a second face and being arranged between the inlet and the out-let of the container such that the first face and the second face are generally coincident with said inlet and said out-let respectively, said partition member extending along the full length of the container from a surface of the container to a radially outer surface of the filter element;
(f) discharge means for discharging liquid from the filtrate receiving-space at a rate sufficient to reduce pressure in the filtrate-receiving space relative to pressure in the suspension-receiving space such that liquid in the suspension flows through the filter element into the filtrate-receiving space, leaving a concentrated fibrous suspension in the suspension-receiving space, the suspension-receiving space communicating with the inlet and the outlet of the container and diminishing in radial width from a point adjacent the inlet circumferentially about the container toward the outlet, the radial width of the sus-pension-receiving space abruptly increasing adjacent the out-let of the container so that pressure in a portion of the suspension-receiving space adjacent the outlet is reduced relative to the pressure in the filtrate-receiving space, thereby facilitating discharge of the concentrated fibrous suspension from the container.
3. Apparatus according to Claim 1 or 2 wherein the radially inward edge of the partition member defines a doctor blade that contacts the radially outer surface of the filter element.
4. Apparatus according to Claim 1 or 2 also com-prising means located within the filter element adjacent the inlet of the container for producing a suction at the surface of the filter element, in addition to the pressure reduction produced by the discharge means, so that a layer of fibers is immediately deposited on a radially outer surface of the filter element.
5. Apparatus according to Claim 1 or 2 also com-prising means located within the filter element adjacent the outlet of the container and the fiber-retaining surface of the filter element for directing a blast of fluid radially out-wardly toward and through said surface of the filter element.
6. An apparatus according to Claim 1 or 2, wherein the outlet is arranged substantially adjacent the inlet.
7. An apparatus according to Claim 1, wherein the plate member includes, adjacent the free end, a U-shaped channel opening toward the filter element thus initially to provide a relatively small increase in the width of the suspension-receiving space, the free end of the plate member curving radially inwardly toward the filter element and then outwardly away from the filter element thus finally to pro-vide a very rapid increase in the width of the suspension-receiving space.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE7316985A SE378433B (en) | 1973-12-17 | 1973-12-17 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1063523A true CA1063523A (en) | 1979-10-02 |
Family
ID=20319408
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA216,129A Expired CA1063523A (en) | 1973-12-17 | 1974-12-16 | Apparatus for continuous separation of a suspension liquid from a fibrous suspension |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5092565A (en) |
| AT (1) | AT336394B (en) |
| CA (1) | CA1063523A (en) |
| DE (1) | DE2457818A1 (en) |
| FI (1) | FI357674A (en) |
| FR (1) | FR2254357A1 (en) |
| IT (1) | IT1027051B (en) |
| NO (1) | NO143280C (en) |
| SE (1) | SE378433B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4750340A (en) * | 1985-10-31 | 1988-06-14 | Kamyr Ab | Apparatus for treating a fibre suspension |
| EP2943613A4 (en) * | 2013-01-11 | 2016-08-03 | Valmet Oy | APPARATUS FOR WASHING AND / OR SPINNING CELLULOSE PULP |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4142292A1 (en) * | 1991-12-20 | 1993-07-01 | Aeg Isolier Kunststoff | Multilayer filter - contains calcinated diatomite as active filter material |
-
1973
- 1973-12-17 SE SE7316985A patent/SE378433B/xx unknown
-
1974
- 1974-11-29 NO NO744319A patent/NO143280C/en unknown
- 1974-12-06 DE DE19742457818 patent/DE2457818A1/en not_active Withdrawn
- 1974-12-10 AT AT985174A patent/AT336394B/en not_active IP Right Cessation
- 1974-12-11 IT IT70601/74A patent/IT1027051B/en active
- 1974-12-12 FI FI3576/74A patent/FI357674A/fi unknown
- 1974-12-16 CA CA216,129A patent/CA1063523A/en not_active Expired
- 1974-12-17 FR FR7441472A patent/FR2254357A1/en active Granted
- 1974-12-17 JP JP49144921A patent/JPS5092565A/ja active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4750340A (en) * | 1985-10-31 | 1988-06-14 | Kamyr Ab | Apparatus for treating a fibre suspension |
| EP2943613A4 (en) * | 2013-01-11 | 2016-08-03 | Valmet Oy | APPARATUS FOR WASHING AND / OR SPINNING CELLULOSE PULP |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2254357B1 (en) | 1980-08-22 |
| ATA985174A (en) | 1976-08-15 |
| FI357674A (en) | 1975-06-18 |
| SE7316985L (en) | 1975-06-18 |
| NO143280B (en) | 1980-09-29 |
| JPS5092565A (en) | 1975-07-24 |
| FR2254357A1 (en) | 1975-07-11 |
| DE2457818A1 (en) | 1975-06-19 |
| IT1027051B (en) | 1978-11-20 |
| SE378433B (en) | 1975-09-01 |
| AT336394B (en) | 1977-05-10 |
| AU7632774A (en) | 1976-06-17 |
| NO143280C (en) | 1981-01-07 |
| NO744319L (en) | 1975-07-14 |
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