CA1324344C - Screen segment for filters for thickening fiber suspensions - Google Patents
Screen segment for filters for thickening fiber suspensionsInfo
- Publication number
- CA1324344C CA1324344C CA000558817A CA558817A CA1324344C CA 1324344 C CA1324344 C CA 1324344C CA 000558817 A CA000558817 A CA 000558817A CA 558817 A CA558817 A CA 558817A CA 1324344 C CA1324344 C CA 1324344C
- Authority
- CA
- Canada
- Prior art keywords
- screen
- segment
- frame
- carriers
- bars
- 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 - Fee Related
Links
- 239000000835 fiber Substances 0.000 title claims abstract description 18
- 239000000725 suspension Substances 0.000 title claims abstract description 12
- 230000008719 thickening Effects 0.000 title claims abstract description 6
- 239000000969 carrier Substances 0.000 claims abstract description 29
- 239000002562 thickening agent Substances 0.000 claims abstract description 9
- 230000000284 resting effect Effects 0.000 claims abstract description 4
- 238000002347 injection Methods 0.000 claims description 3
- 239000007924 injection Substances 0.000 claims description 3
- 229910000831 Steel Inorganic materials 0.000 claims description 2
- 239000010959 steel Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 7
- 238000000034 method Methods 0.000 abstract description 2
- 238000000465 moulding Methods 0.000 abstract 1
- 230000008569 process Effects 0.000 abstract 1
- 239000000463 material Substances 0.000 description 9
- 239000002657 fibrous material Substances 0.000 description 2
- 239000000706 filtrate Substances 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 230000033001 locomotion Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- 238000004061 bleaching Methods 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- 239000010893 paper waste Substances 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/66—Pulp catching, de-watering, or recovering; Re-use of pulp-water
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/18—De-watering; Elimination of cooking or pulp-treating liquors from the pulp
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
- D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
- D21D5/02—Straining or screening the pulp
- D21D5/04—Flat screens
- D21D5/046—Rotary screens
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
- Y10S264/48—Processes of making filters
Abstract
Abstract In a sector-shaped screen segment for disk filters or thickeners with a folded screen for thickening fiber sus-pensions comprising a frame, two screen carriers and a screen resting on the outer sides of the screen carriers, manufacture is rendered simpler and less expensive by the frame and the screen carriers forming an integral molded part in which the screen is embedded in the molding pro-cess.
Description
13~3~
Screen Segment for Filters for thickening Fiber Suspensions The invention relates to a sector-shaped screen segment for rotating disk filters or thickeners with a folded screen for thickening fiber suspensions.
In the production of wood pulp and cellulose and the pro-cessing of waste paper and other fibrous materials, a fiber ~uspension is often treated at substance densities of between approximately 0.3 % and approximately 3 ~. The further processing of the raw materials by grinding or bleaching and the temporary storing of the fibrous material in vats require a higher concentration which is economically obtainable with rotating disk filters or thickeners with a folded screen. In both cases, a drum which rotates about a horizontal axis dips into a trough into which the fiber suspension which is to be thickened i9 continuously intro-duced. The drum which is covered on the outside with a woven screen is of accordion-like configuration to increase the screen area. In a known disk filter, such as, for example, that offered by Hedemora Pulp Nachinery, the drum is com-prised of several disk-~haped units which are mounted on a common, rotatably mounted and driven supporting pipe and each consist of several sector-shaped screen segments which are contiguous along radii and are covered on the outer side with the woven screen which together with screen carriers defining a cavity forms the end faces of the filter disks.
As the disk filter dips into the fiber suspension and turns slowly in it, water passes out of the fi~er suspension through ~ 32~3~
the screen into the interior of the rotating drum, and a fi-brous fleece forms on the outer side of the screen and in-creases the filtering effect. The arrangement is designed to produce between the level of the fiber suspension in the trough and the level of the water flowing off from the drum interior through the supporting pipe, a hydrostatic pressure difference which causes continuous filtration. To remove from the filter disks the continuously increasing layer of fibers accumulating on the screen as the fiber suspension in the trough passes through it, there are arranged on the trough, above the fiber suspension to be filtered, rake-like scrapers which form a kind of chute on which the layers of fibers which have been removed from the filter disks slide to a location outside the trough. Removal of the layers of fibers from the screen may be facilitated by provision of a spraying pipe above the disk filter to spray off and thereby remove the layers of fibers from the screen.
In the known disk filter described above, the screen seg-ments have a kind of frame with two lateral, radially ex-tending legs and a circumferentially outer leg, and the screen carriers arranged in axially spaced relation to each other consist of a welded wire grid with a woven plastic screen resting on it. The screen forms a filter bag which has a zip fastener and has been shrunk onto the frame and the screen carriers.
In known thickeners with a folded screen, the circumferen-tially extending folds are less deep than in a disk filter.
1 3 2 ~ 3 ~ l~
In another known disk filter, the screen carriers consist of perforated metal plates with apertures of relatively large diameter.
The known sector-shaped screen segments are disadvantageous in several respects: Firstly, the supporting structures for the woven screen consisting of frame and screen carriers involve quite high manufacturing expenditure, which results in relatively high costs. In addition, these screen struc-tures are not particularly stable - it must be remembered that the filter disks have a diameter of the order of mag-nitude of 2 m - and even if the rotating filter disks run slightly out of true at the sides, this causes the woven screen to run sideways against the scrapers removing the layer of fibers from the drum, the spraying pipes and the like, and, for this reason, in the known disk filter de-scribed above, the filter disks are guided at the sides in the area in which the layer of fibers is removed. Finally, relative motions between the woven screen and the scraen carriers supporting it result in wear and tear of the screen and hence in decreased service life.
The object underlying the invention is to create a sector-shaped screen segment (viewed from the side, the known screen segments described above have approximately the shape of the sector of a circle with the top cut off) for rotating disk filters or thickeners with a folded screen for thickening fiber suspensions which is simpler and hence less expensive to manufacture, particularly also as far as attachment of the ~creen is concerned.
~32~3~
Proceeding from a screen segment with a frame having a ra-dially outer leg and a lateral leg at each of its two sides which, in particular, extend in the radial direction, and attached to said legs two screen carriers arranged in -axially - spaced relation to each other and forming together with a screen resting on them the two main surfaces of the screen segment, this object is achieved, in accordance with the invention, by at least the frame legs being in the form of molded parts in which the screen is embedded, with pro-vision being made in a preferred embodiment for the screen to also be embedded in the screen carriers which are components of a molded part. Manufacture is rsndered par.icularly simple by the screen carriers being molded to the frame legs.
Accordingly, as in the known screen segments, in the inven-tive construction, too, the woven screen forms the main sur-faces of the screen segment at the sides or the end faces, more particularly, not only when the screen simply rests on the screen carrier~ but also in the preferred embodi-ment in which the screen is also embedded in the screen carriers which are in the form of molded parts, insofar as embedding is carried out in such a way that the material of the screen carriers does not protrude beyond the outer side of the woven screen. No further special steps are required for attaching the screen since it is automatically attached to the frame and/or the screen carriers when these parts of the screen segment are being molded. Two separate screen sections which have been cut to size can be used for the two main surfaces but it is, of course, also possible, as in the known disk filter described above, for a filter bag ~32~3~
to be placed in the mold and for the embedding to be carried out when the frame and/or the screen carriers are being molded.
In principle, the complete frame of a screen segment and also its two screen carriers can be manufactured as an in-tegral molded part. However, to enable use of simpler and hence less expensive molds, an embodiment is recommended in which the frame legs are divided along a center plane extending perpendicularly to the axis of rotation of the filter disk and the frame leg halves together with the associated screen carrier of the respective segment half form an integral, half-dish-like molded part in which a sector-shaped screen section which has been cut to size is embedded. The thus manufactured screen segment halves can then be adhered, welded, screwed toqether or simply attached to each other in some other way. However, a screw connection is preferred as a damaged or worn screen segment or screen segment half is then particularly easily and quickly replaced, which shortens the idle time of the disk filter or thickener with folded screen.
The molded parts can be metal die-cast or in~ection molded parts. The inventive screen segments are particularly in-expensive and light if the molded part is a plastic in-jection molded part.
Any suitable material can be used for the screen but a woven structure made of rust-proof steel wires or plastic filaments or plastic wires is particularly recommended.
~ 32~3~4 It has also proven to be advantageous in the inventive screen segment f or each screen carrier to be in the f orm of a grid comprised of bars and, in particular, for the bars to be arranged so as to extend radially and in the direction of rotation. The bars extending in the direction of rotation are then set back in the direction toward the segment interior in relation to the radially extending bars and the screen is embedded only in the radially extending bars as the form stability of the woven screen surfaces is then particularly good on account of the slight spacing be-tween the supports by which the screen is held.
Particular emphasis is to be placed on the fact that the embedding of the screen in the screen carriers and/or the frame prevents relative motions between the screen and the parts carrying it, above all, when the screen i9 em-bedded in the material of the screen carriers. The in-ventive screen segments, therefore, have a substantially longer service life than the screen segments known from the prior art. In this connection, it should, furthermore, be noted that it is, of course, not necessary for the screen to be embedded in the molded material throughout the entire thickness of the screen. It would, for example, be sufficient, in the case of a woven screen, for the wire or filament curvatures facing the screen carriers or frame legs to be embedded in the molded material even though em-bodiments are preferred in which the screen is embedded in the molded material to such a depth that the molded material is flush with the outer side of the screen.
~32~3l~
Further features, advantages and details of the invention will become apparent from the following description and the appended drawings of two embodiments of the inventive screen segment. In the drawings:
igure 1 is a front end view (in the axial direction) of an inventive screen segment for a disk filter;
igure 2 is a section through the screen segment for the disk filter along line 2-2 in Figure 1;
igure 3 is a section through a radially extending bar of one of the two screen carriers including an em-bedded screen according to line 3-3 in Figure 1;
igure 4 is a front end view corresponding to Figure 1 of an inventive screen segment for a thickener with a folded screen7 and igure 5 is a section through this screen segment according to line 5-S in Figure 4.
The screen segment for a disk filter shown in Figures 1 to 3 consists essentially of two woven screen sections 10 which have been cut to size and two half-dishes 12, 14 in the form of integral molded parts, each of which forms a screen carrier 16 and a frame half 18. The two frame halves to-gether produce a radially outer frame leg 20 and two lateral, radially extending frame legs 22 and are firmly connected to each other along these frame legs by means of screws 24 and 132~3~4 threaded bores 26. Recesses 28 are provided in the half-dish 12 for accommodating the screw heads. As in the illustrated embodiment, the frame halves of the inventive screen segment are closed and, therefore, also have an inner frame leg 30, with the two halves of this inner frame leg being arranged in axially spaced relation to each other, as shown in Figure 2, to enable the filtrate to flow down into a screen segment carrier.
The screen carriers 16 consist of radially extending bars 32 and bars 34 extending transversely thereto, which are inte~
grally connected with one another and the frame halves 18 as the entire frame halves each form one single molded part, more particularly, a plastic injection molded part. The transverse bars 34 are set back in relation to the radial bars 32 in the direction towards the interior of the screen segment, as is clearly apparent -from Figure 2, while, in accordance with the invention, the outer end faces of the radial bars 32 are in alignment with the outer end faces of the frame halves 18. Since the transverse bars 34 lie against one another, as likewise shown in Figure 2, the previously made statement that the screen carriers are to be arranged in axially spaced relation to each other, is, of course, only to be so interpreted that the bearing surfaces of the two screen carriers supporting the screens lie in axially spaced relation to each other.
In accordance with the invention, each of the woven screen sections 10 which have been cut to si~e is embedded in the screen supports formed by the outer end faces of the frame 1~2~3~
g legs 20, 22, 30 and of the radial bars 32 at least throughout part of the thickness of the screen, but preferably through-out the entire screen thickness, as is apparent from Figure 3 which shows in section one of the radial bars 32 and one of the woven screen sections 10 cut to size. From this section it is also evident that in the preferred embodiment of the inventive screen segment, the material of the carrying structure does not protrude outwardly beyond the outermost elevations in the screen, i.e., the woven screen material.
The two frame halves can be particularly simply and inex-pensively manufactured as plastic injected molded parts.
A woven screen section 10 cut to size is placed in the injection mold and the frame half is then injected, the woven screen being simultaneously embedded in the plastic forming the frame half and thereby anchored on the frame and on the screen carrier.
Since the screen segment shown in Figures 4 and 5 differs from a thickener with a folded screen essentially only in that the radial extension of the frame and of the screen carriers i5 smaller than in the case of a screen segment for a disk filter, the elements of the second embodiment corresponding to those of the first embodiment have been designated by the same reference numerals as in Figures 1 to 3, but with the addition of an apostrophe, which eliminates the necessity for a description of the details shown in Figures 4 and 5.
It is particularly advantageous that the bars of the two 132~34L~
frame halves which do not carry the woven screen are of such arrangement and dimensions that, on the one hand, they lie against one another (vide Figures 2 and 5), which increases the stability of the screen segment, yet, on the other hand, there remains a relatively large flow cross-section for the filtrate between the outward-ly oriented edges of these bars and the woven screen ma-terial.
The invention further relates to the method for manu-facturing the sc-een segment which is characterized in that the screen is placed in a mold for manufacture of the frame and/or the screen carrier and the frame and/or the screen carrier is/are then cast.
Screen Segment for Filters for thickening Fiber Suspensions The invention relates to a sector-shaped screen segment for rotating disk filters or thickeners with a folded screen for thickening fiber suspensions.
In the production of wood pulp and cellulose and the pro-cessing of waste paper and other fibrous materials, a fiber ~uspension is often treated at substance densities of between approximately 0.3 % and approximately 3 ~. The further processing of the raw materials by grinding or bleaching and the temporary storing of the fibrous material in vats require a higher concentration which is economically obtainable with rotating disk filters or thickeners with a folded screen. In both cases, a drum which rotates about a horizontal axis dips into a trough into which the fiber suspension which is to be thickened i9 continuously intro-duced. The drum which is covered on the outside with a woven screen is of accordion-like configuration to increase the screen area. In a known disk filter, such as, for example, that offered by Hedemora Pulp Nachinery, the drum is com-prised of several disk-~haped units which are mounted on a common, rotatably mounted and driven supporting pipe and each consist of several sector-shaped screen segments which are contiguous along radii and are covered on the outer side with the woven screen which together with screen carriers defining a cavity forms the end faces of the filter disks.
As the disk filter dips into the fiber suspension and turns slowly in it, water passes out of the fi~er suspension through ~ 32~3~
the screen into the interior of the rotating drum, and a fi-brous fleece forms on the outer side of the screen and in-creases the filtering effect. The arrangement is designed to produce between the level of the fiber suspension in the trough and the level of the water flowing off from the drum interior through the supporting pipe, a hydrostatic pressure difference which causes continuous filtration. To remove from the filter disks the continuously increasing layer of fibers accumulating on the screen as the fiber suspension in the trough passes through it, there are arranged on the trough, above the fiber suspension to be filtered, rake-like scrapers which form a kind of chute on which the layers of fibers which have been removed from the filter disks slide to a location outside the trough. Removal of the layers of fibers from the screen may be facilitated by provision of a spraying pipe above the disk filter to spray off and thereby remove the layers of fibers from the screen.
In the known disk filter described above, the screen seg-ments have a kind of frame with two lateral, radially ex-tending legs and a circumferentially outer leg, and the screen carriers arranged in axially spaced relation to each other consist of a welded wire grid with a woven plastic screen resting on it. The screen forms a filter bag which has a zip fastener and has been shrunk onto the frame and the screen carriers.
In known thickeners with a folded screen, the circumferen-tially extending folds are less deep than in a disk filter.
1 3 2 ~ 3 ~ l~
In another known disk filter, the screen carriers consist of perforated metal plates with apertures of relatively large diameter.
The known sector-shaped screen segments are disadvantageous in several respects: Firstly, the supporting structures for the woven screen consisting of frame and screen carriers involve quite high manufacturing expenditure, which results in relatively high costs. In addition, these screen struc-tures are not particularly stable - it must be remembered that the filter disks have a diameter of the order of mag-nitude of 2 m - and even if the rotating filter disks run slightly out of true at the sides, this causes the woven screen to run sideways against the scrapers removing the layer of fibers from the drum, the spraying pipes and the like, and, for this reason, in the known disk filter de-scribed above, the filter disks are guided at the sides in the area in which the layer of fibers is removed. Finally, relative motions between the woven screen and the scraen carriers supporting it result in wear and tear of the screen and hence in decreased service life.
The object underlying the invention is to create a sector-shaped screen segment (viewed from the side, the known screen segments described above have approximately the shape of the sector of a circle with the top cut off) for rotating disk filters or thickeners with a folded screen for thickening fiber suspensions which is simpler and hence less expensive to manufacture, particularly also as far as attachment of the ~creen is concerned.
~32~3~
Proceeding from a screen segment with a frame having a ra-dially outer leg and a lateral leg at each of its two sides which, in particular, extend in the radial direction, and attached to said legs two screen carriers arranged in -axially - spaced relation to each other and forming together with a screen resting on them the two main surfaces of the screen segment, this object is achieved, in accordance with the invention, by at least the frame legs being in the form of molded parts in which the screen is embedded, with pro-vision being made in a preferred embodiment for the screen to also be embedded in the screen carriers which are components of a molded part. Manufacture is rsndered par.icularly simple by the screen carriers being molded to the frame legs.
Accordingly, as in the known screen segments, in the inven-tive construction, too, the woven screen forms the main sur-faces of the screen segment at the sides or the end faces, more particularly, not only when the screen simply rests on the screen carrier~ but also in the preferred embodi-ment in which the screen is also embedded in the screen carriers which are in the form of molded parts, insofar as embedding is carried out in such a way that the material of the screen carriers does not protrude beyond the outer side of the woven screen. No further special steps are required for attaching the screen since it is automatically attached to the frame and/or the screen carriers when these parts of the screen segment are being molded. Two separate screen sections which have been cut to size can be used for the two main surfaces but it is, of course, also possible, as in the known disk filter described above, for a filter bag ~32~3~
to be placed in the mold and for the embedding to be carried out when the frame and/or the screen carriers are being molded.
In principle, the complete frame of a screen segment and also its two screen carriers can be manufactured as an in-tegral molded part. However, to enable use of simpler and hence less expensive molds, an embodiment is recommended in which the frame legs are divided along a center plane extending perpendicularly to the axis of rotation of the filter disk and the frame leg halves together with the associated screen carrier of the respective segment half form an integral, half-dish-like molded part in which a sector-shaped screen section which has been cut to size is embedded. The thus manufactured screen segment halves can then be adhered, welded, screwed toqether or simply attached to each other in some other way. However, a screw connection is preferred as a damaged or worn screen segment or screen segment half is then particularly easily and quickly replaced, which shortens the idle time of the disk filter or thickener with folded screen.
The molded parts can be metal die-cast or in~ection molded parts. The inventive screen segments are particularly in-expensive and light if the molded part is a plastic in-jection molded part.
Any suitable material can be used for the screen but a woven structure made of rust-proof steel wires or plastic filaments or plastic wires is particularly recommended.
~ 32~3~4 It has also proven to be advantageous in the inventive screen segment f or each screen carrier to be in the f orm of a grid comprised of bars and, in particular, for the bars to be arranged so as to extend radially and in the direction of rotation. The bars extending in the direction of rotation are then set back in the direction toward the segment interior in relation to the radially extending bars and the screen is embedded only in the radially extending bars as the form stability of the woven screen surfaces is then particularly good on account of the slight spacing be-tween the supports by which the screen is held.
Particular emphasis is to be placed on the fact that the embedding of the screen in the screen carriers and/or the frame prevents relative motions between the screen and the parts carrying it, above all, when the screen i9 em-bedded in the material of the screen carriers. The in-ventive screen segments, therefore, have a substantially longer service life than the screen segments known from the prior art. In this connection, it should, furthermore, be noted that it is, of course, not necessary for the screen to be embedded in the molded material throughout the entire thickness of the screen. It would, for example, be sufficient, in the case of a woven screen, for the wire or filament curvatures facing the screen carriers or frame legs to be embedded in the molded material even though em-bodiments are preferred in which the screen is embedded in the molded material to such a depth that the molded material is flush with the outer side of the screen.
~32~3l~
Further features, advantages and details of the invention will become apparent from the following description and the appended drawings of two embodiments of the inventive screen segment. In the drawings:
igure 1 is a front end view (in the axial direction) of an inventive screen segment for a disk filter;
igure 2 is a section through the screen segment for the disk filter along line 2-2 in Figure 1;
igure 3 is a section through a radially extending bar of one of the two screen carriers including an em-bedded screen according to line 3-3 in Figure 1;
igure 4 is a front end view corresponding to Figure 1 of an inventive screen segment for a thickener with a folded screen7 and igure 5 is a section through this screen segment according to line 5-S in Figure 4.
The screen segment for a disk filter shown in Figures 1 to 3 consists essentially of two woven screen sections 10 which have been cut to size and two half-dishes 12, 14 in the form of integral molded parts, each of which forms a screen carrier 16 and a frame half 18. The two frame halves to-gether produce a radially outer frame leg 20 and two lateral, radially extending frame legs 22 and are firmly connected to each other along these frame legs by means of screws 24 and 132~3~4 threaded bores 26. Recesses 28 are provided in the half-dish 12 for accommodating the screw heads. As in the illustrated embodiment, the frame halves of the inventive screen segment are closed and, therefore, also have an inner frame leg 30, with the two halves of this inner frame leg being arranged in axially spaced relation to each other, as shown in Figure 2, to enable the filtrate to flow down into a screen segment carrier.
The screen carriers 16 consist of radially extending bars 32 and bars 34 extending transversely thereto, which are inte~
grally connected with one another and the frame halves 18 as the entire frame halves each form one single molded part, more particularly, a plastic injection molded part. The transverse bars 34 are set back in relation to the radial bars 32 in the direction towards the interior of the screen segment, as is clearly apparent -from Figure 2, while, in accordance with the invention, the outer end faces of the radial bars 32 are in alignment with the outer end faces of the frame halves 18. Since the transverse bars 34 lie against one another, as likewise shown in Figure 2, the previously made statement that the screen carriers are to be arranged in axially spaced relation to each other, is, of course, only to be so interpreted that the bearing surfaces of the two screen carriers supporting the screens lie in axially spaced relation to each other.
In accordance with the invention, each of the woven screen sections 10 which have been cut to si~e is embedded in the screen supports formed by the outer end faces of the frame 1~2~3~
g legs 20, 22, 30 and of the radial bars 32 at least throughout part of the thickness of the screen, but preferably through-out the entire screen thickness, as is apparent from Figure 3 which shows in section one of the radial bars 32 and one of the woven screen sections 10 cut to size. From this section it is also evident that in the preferred embodiment of the inventive screen segment, the material of the carrying structure does not protrude outwardly beyond the outermost elevations in the screen, i.e., the woven screen material.
The two frame halves can be particularly simply and inex-pensively manufactured as plastic injected molded parts.
A woven screen section 10 cut to size is placed in the injection mold and the frame half is then injected, the woven screen being simultaneously embedded in the plastic forming the frame half and thereby anchored on the frame and on the screen carrier.
Since the screen segment shown in Figures 4 and 5 differs from a thickener with a folded screen essentially only in that the radial extension of the frame and of the screen carriers i5 smaller than in the case of a screen segment for a disk filter, the elements of the second embodiment corresponding to those of the first embodiment have been designated by the same reference numerals as in Figures 1 to 3, but with the addition of an apostrophe, which eliminates the necessity for a description of the details shown in Figures 4 and 5.
It is particularly advantageous that the bars of the two 132~34L~
frame halves which do not carry the woven screen are of such arrangement and dimensions that, on the one hand, they lie against one another (vide Figures 2 and 5), which increases the stability of the screen segment, yet, on the other hand, there remains a relatively large flow cross-section for the filtrate between the outward-ly oriented edges of these bars and the woven screen ma-terial.
The invention further relates to the method for manu-facturing the sc-een segment which is characterized in that the screen is placed in a mold for manufacture of the frame and/or the screen carrier and the frame and/or the screen carrier is/are then cast.
Claims (9)
1. A sector-shaped screen segment for rotating disc filters or thickeners with a folded screen for thickening fiber suspensions, comprising a frame having a radially outer leg and a lateral leg at each of its two sides which extend in particular, in radial direction, two screen carriers being attached to said legs and forming screen supports arranged in axially spaced relationship to one another and, together with a screen resting thereon the two main surfaces of said screen segment, both said screen carriers and said frame legs being in the form of molded parts, characterized in that said screen is embedded in said frame legs and said screen carriers.
2. Screen segment as defined in claim 1, characterized in that said screen carriers are molded onto said frame legs.
3. Screen segment as defined in claim 2, characterized in that said frame legs are divided along a center plane of said screen segment extending at right angles to the axis of rotation thereby defining two segment halves each having a frame half, and that the frame half together with the screen carrier of one segment half forms an integral, half-dish-like molded part.
4. Screen segment as defined in claim 1, characterized in that said molded part is a plastic injection molded part.
5. Screen segment as defined in claim 1, characterized in that said screen is a web of rust-proof steel wires.
6. Screen segment as defined in ciaim 1, characterized in that said screen is a web of plastic filaments.
7. Screen segment as defined in claim 3, characterized in that the two half-dish-like molded parts are joined to one another along said frame legs by screws.
8. Screen segment as defined in claim 1, characterized in that each screen carrier is designed as a grid formed of bars.
9. Screen segment as defined in claim 8, characterized in that said bars comprise radially extending bars and cross bars extending transversely thereto, that the cross bars are set back towards the segment interior in relation to the bars extending in a radial direction and that said screen is embedded only in said radially extending bars.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3706402.9 | 1987-02-27 | ||
| DE3706402A DE3706402C1 (en) | 1987-02-27 | 1987-02-27 | Sieve segment for filters for thickening fiber suspensions |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1324344C true CA1324344C (en) | 1993-11-16 |
Family
ID=6321947
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000558817A Expired - Fee Related CA1324344C (en) | 1987-02-27 | 1988-02-12 | Screen segment for filters for thickening fiber suspensions |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US4950403A (en) |
| EP (1) | EP0280094B1 (en) |
| JP (1) | JP2645057B2 (en) |
| AT (1) | ATE54967T1 (en) |
| CA (1) | CA1324344C (en) |
| DE (2) | DE3706402C1 (en) |
| FI (1) | FI85341C (en) |
Families Citing this family (37)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5254250A (en) * | 1991-05-30 | 1993-10-19 | Membrex, Inc. | Rotary filtration device and filter pack therefor |
| US5679249A (en) * | 1991-12-24 | 1997-10-21 | Pall Corporation | Dynamic filter system |
| US6117322A (en) * | 1993-06-23 | 2000-09-12 | Pall Corporation | Dynamic filter system |
| AT401069B (en) * | 1993-06-23 | 1996-06-25 | Leripa Kunststoff Gmbh & Co Kg | Edge seal for dewatering elements |
| AT403064B (en) * | 1995-09-15 | 1997-11-25 | Andritz Patentverwaltung | Disc filter for separating liquids from a suspension, especially fibrous suspension |
| US5707517A (en) * | 1995-11-27 | 1998-01-13 | Membrex, Inc. | Immersible rotary disc filtration device |
| KR100472014B1 (en) | 1996-08-20 | 2005-05-03 | 뷜러아게 | Planar Separator |
| US5766472A (en) * | 1996-10-29 | 1998-06-16 | Illinois Tool Works Inc. | Method and apparatus for a filter assembly |
| DE19706601C1 (en) * | 1997-02-20 | 1998-11-12 | Buehler Ag | Screen frame for plansifter and process for its production |
| DE69813521T2 (en) * | 1997-03-01 | 2003-12-24 | United Wire Ltd | FILTER SCREEN AND SUPPORT FRAME THEREFOR |
| US5993674A (en) * | 1998-02-24 | 1999-11-30 | Membrex, Inc. | Rotary disc filtration device with means to reduce axial forces |
| US6305549B1 (en) * | 1999-07-06 | 2001-10-23 | Southwestern Wire Cloth, Inc. | Vibrating screen assembly of dissimilar materials |
| US20010050250A1 (en) | 1999-09-14 | 2001-12-13 | Olli Hognabba | Corrosion-resistant filter element |
| SE526692E (en) * | 2003-02-27 | 2012-12-28 | Veolia Water Solutions & Tech | Module for structure of disk filter |
| AT412259B (en) * | 2003-06-04 | 2004-12-27 | Andritz Ag Maschf | METHOD FOR PRODUCING A SECTOR-SHAPED FILTER ELEMENT AND FILTER ELEMENT |
| US20050027006A1 (en) | 2003-07-28 | 2005-02-03 | Reuben Matalon | Methods and materials for treating conditions associated with metabolic disorders |
| US20070108107A1 (en) * | 2005-11-15 | 2007-05-17 | Morrow Deborah E | Disposable pre-tensioned sieve frame and method of making same |
| EP1872843A1 (en) * | 2006-06-26 | 2008-01-02 | Hydrotech Veolia Water Systems Aktiebolag | A filter frame for use in a disc filter |
| EP2612696B8 (en) | 2006-08-14 | 2017-12-20 | Evoqua Water Technologies LLC | Method of filtering |
| US8801929B2 (en) * | 2007-07-18 | 2014-08-12 | Evoqua Water Technologies Llc | Trash tolerant filter support for a disc filter |
| US8118175B2 (en) | 2007-07-18 | 2012-02-21 | Siemens Industry, Inc. | Venting device for a disc filter |
| CN101980969A (en) | 2008-03-28 | 2011-02-23 | 西门子水处理技术公司 | Hybrid aerobic and anaerobic wastewater and sludge treatment systems and methods |
| US8894856B2 (en) | 2008-03-28 | 2014-11-25 | Evoqua Water Technologies Llc | Hybrid aerobic and anaerobic wastewater and sludge treatment systems and methods |
| US9359236B2 (en) | 2010-08-18 | 2016-06-07 | Evoqua Water Technologies Llc | Enhanced biosorption of wastewater organics using dissolved air flotation with solids recycle |
| SE535159C2 (en) * | 2010-09-02 | 2012-05-02 | Veolia Water Solutions & Tech | Method of manufacturing a filter segment into a disk filter as well as the filter segment |
| CN102614703A (en) * | 2011-01-31 | 2012-08-01 | 江苏博思达环保科技有限公司 | Disks for rotary disk filter |
| WO2013032958A1 (en) * | 2011-08-29 | 2013-03-07 | Karl Gabrielsson | A filter segment with a light weight frame |
| DE102012222400A1 (en) | 2012-12-06 | 2014-06-26 | BSH Bosch und Siemens Hausgeräte GmbH | Disk filter plate for filter system for filtering intake air of base supporting device, has disk-shaped carrier element and one or multiple filter material elements, which flow at two or multiple surfaces of carrier element |
| GB2527989B (en) | 2013-05-06 | 2020-04-22 | Evoqua Water Tech Llc | Enhanced biosorption of wastewater organics using dissolved air flotation with solids recycle |
| PL3151943T3 (en) | 2014-06-05 | 2021-05-31 | Evoqua Water Technologies Llc | Filtering panel and method of making the same |
| US11065567B2 (en) * | 2015-07-03 | 2021-07-20 | Gaudfrin | Sector having progressive thickness |
| ES2927357T3 (en) | 2016-08-12 | 2022-11-04 | Evoqua Water Tech Llc | Dual Media Disc Filter Disc Filter Pre-Screen |
| EP3526394B1 (en) * | 2016-10-17 | 2020-07-08 | Andritz Oy | Screen assembly for pulp digesters and other treatment vessels in pulp production |
| SE1750701A1 (en) | 2017-06-02 | 2018-10-23 | Nordic Water Prod Ab | Filter element for use in a filter disc |
| CN107227649A (en) * | 2017-06-13 | 2017-10-03 | 太仓市宇航造纸机械厂 | A kind of paper grade (stock) double-layer filtering net |
| US11000791B2 (en) * | 2019-03-06 | 2021-05-11 | Veolia Water Solutions & Technologies Support | Rotary disc filter having backwash guides |
| US20220347603A1 (en) * | 2021-04-30 | 2022-11-03 | Pall Corporation | Filter disk segments |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1685085A (en) * | 1924-02-01 | 1928-09-25 | United Filters Corp | Dewatering apparatus |
| US1746409A (en) * | 1926-12-06 | 1930-02-11 | Oliver United Filters Inc | Filter leaf |
| US1767078A (en) * | 1927-11-29 | 1930-06-24 | Johnson John | Screen for filter presses |
| US2444147A (en) * | 1945-03-15 | 1948-06-29 | Air Maze Corp | Liquid filter element |
| US2682205A (en) * | 1949-06-28 | 1954-06-29 | Bertram J Vincent | Screen plate for papermaking machines |
| US2964194A (en) * | 1957-04-17 | 1960-12-13 | Dorr Oliver Inc | Filter construction |
| US3610419A (en) * | 1969-06-09 | 1971-10-05 | Improved Machinery Inc | Filter leaf |
| US3679061A (en) * | 1970-06-15 | 1972-07-25 | Envirotech Corp | Molded filter leaf |
| US3917534A (en) * | 1974-04-17 | 1975-11-04 | Plastic Tech Inc | Filter sector |
| FR2375893A1 (en) * | 1976-12-31 | 1978-07-28 | Eurogest | Two=part filter casing with an inclined join - enabling construction by injection moulding techniques |
| US4077887A (en) * | 1977-05-17 | 1978-03-07 | Sigmund Coll Langvik | Filter disc for vacuum filter system |
| US4330405A (en) * | 1980-09-29 | 1982-05-18 | Davis Kent L | Vacuum disc filter |
| NL8400662A (en) * | 1984-03-01 | 1985-10-01 | Amafilter Bv | DISC-FILTER ELEMENT. |
| SE453158B (en) * | 1985-02-20 | 1988-01-18 | Bjarne Nilsson | DISC FILTER ELEMENT FOR A ROTABLE DISC FILTER |
-
1987
- 1987-02-27 DE DE3706402A patent/DE3706402C1/en not_active Expired
-
1988
- 1988-02-05 DE DE8888101672T patent/DE3860346D1/en not_active Expired - Fee Related
- 1988-02-05 AT AT88101672T patent/ATE54967T1/en not_active IP Right Cessation
- 1988-02-05 EP EP88101672A patent/EP0280094B1/en not_active Expired - Lifetime
- 1988-02-10 US US07/154,634 patent/US4950403A/en not_active Expired - Lifetime
- 1988-02-12 FI FI880649A patent/FI85341C/en not_active IP Right Cessation
- 1988-02-12 CA CA000558817A patent/CA1324344C/en not_active Expired - Fee Related
- 1988-02-26 JP JP63042395A patent/JP2645057B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0280094A3 (en) | 1989-03-01 |
| DE3860346D1 (en) | 1990-08-30 |
| US4950403A (en) | 1990-08-21 |
| JPS63219691A (en) | 1988-09-13 |
| DE3706402C1 (en) | 1988-07-07 |
| ATE54967T1 (en) | 1990-08-15 |
| EP0280094B1 (en) | 1990-07-25 |
| FI880649A0 (en) | 1988-02-12 |
| FI880649A (en) | 1988-08-28 |
| FI85341B (en) | 1991-12-31 |
| EP0280094A2 (en) | 1988-08-31 |
| JP2645057B2 (en) | 1997-08-25 |
| FI85341C (en) | 1992-04-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |