CA2676660A1 - Distribution unit in an inlet box for a dewatering press - Google Patents
Distribution unit in an inlet box for a dewatering press Download PDFInfo
- Publication number
- CA2676660A1 CA2676660A1 CA002676660A CA2676660A CA2676660A1 CA 2676660 A1 CA2676660 A1 CA 2676660A1 CA 002676660 A CA002676660 A CA 002676660A CA 2676660 A CA2676660 A CA 2676660A CA 2676660 A1 CA2676660 A1 CA 2676660A1
- Authority
- CA
- Canada
- Prior art keywords
- distribution
- inlet
- slit
- hatch
- dewatering
- 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.)
- Abandoned
Links
- 238000009826 distribution Methods 0.000 title claims abstract description 130
- 239000000835 fiber Substances 0.000 claims abstract description 44
- 239000000725 suspension Substances 0.000 claims abstract description 42
- 238000007789 sealing Methods 0.000 claims abstract description 3
- 238000003892 spreading Methods 0.000 claims description 5
- 239000000706 filtrate Substances 0.000 description 8
- 239000002184 metal Substances 0.000 description 7
- 230000008439 repair process Effects 0.000 description 7
- 238000012423 maintenance Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000004140 cleaning Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000007689 inspection Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000007257 malfunction Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000004886 process control Methods 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
- D21F1/02—Head boxes of Fourdrinier machines
-
- 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
- D21F1/80—Pulp catching, de-watering, or recovering; Re-use of pulp-water using endless screening belts
Landscapes
- Paper (AREA)
Abstract
The present invention relates to a distribution unit (1) for adding of a fibre suspension to an inlet space (52) at a dewatering press. The distribution unit comprises a distribution housing (2), which forms at least one distribution slit (4, 4'), which distribution slit is intended to be connected to the inlet space of the dewatering press (52), and at least one inlet member (6) for adding of the fibre suspension to the distribution slit. The distribution housing (2) is provided with at least one opening (8) to the distribution slit (4, 4') and a thereto matching hatch (10) for sealing of the opening (8), and that the hatch is hinged to the distribution housing (2) so that it is pivotable relative to the distribution housing (2) between a first position (Pl) and a second position (P2). The present invention also comprise an inlet box (30) comprising on or more of said distribution units (1) and a use of a mentioned distribution unit or inlet box for a twin wire press.
Description
Distribution unit in an inlet box for a dewatering press The present invention relates to a distribution unit for adding a fibre suspension to an inlet space of a dewatering press, an inlet box comprising one or more of said distribution units, a twin-wire press with said inlet box and a use of said distribution unit or inlet box for a twin-wire press.
Dewatering presses for dewatering of a fibre suspension and forming of a continuous web thereof are previously known. One example of a known dewatering press is a twin-wire press. Dewatering of the pulp is usually done from an inlet pulp concentration of 3-8 percentages by weight to an outlet pulp concentration of percentages by weight. According to the state of the art, such twin-wire presses comprises lower rolls, an endless lower wire running in a path around the lower rolls, upper rolls, and an endless upper wire running in a path around the upper rolls. The two wires co-operate with each other along dewatering sections of said paths, in which the wires forms a wedge-shaped dewatering space for the fibre suspension between each other. During displacement of the wires along said dewatering sections, the wires thus successively compresses the fibre suspension in the wedge-shaped space, whereby the fibre suspension is initially pressed and dewatered and formed to a continuous fibre web between the wires.
An inlet box provides for supply of fibre suspension to the wedge-shaped dewatering space between the wires. The known twin-wire press further comprises two dewatering tables supporti:ng the respective wire in said dewatering sections of the path, such that the wedge-shaped dewatering space is formed between the wires, and a roll arrangement situated after the dewatering tables, as seen in the direction of movement of the wires, for finally pressing and dewatering of the fibre web between the wires, so that the fibre web will get a desired dryness. Alongside the longitudinal direction of the wires, in the wedge-shaped dewatering space, there are perforated dewatering elements that are arranged against the wires outside the dewatering space.
Formed filtrate flows through the wires and the perforated dewatering elements and is lead away to upper and lower outlet boxes, respectively, arranged at the dewatering tables.
The upper and lower outlet box, respectively, may be divided into several chambers whereby a filtrate that flows through the upper and lower dewatering elements, respectively, may be divided into partial filtrate in two or more chambers in the respective outlet box.
In the traditional twin-wire press the geometry for the inlet box, for adding of the fibre suspension to the wedge-shaped dewatering space between the wires, is very difficult to set to obtain correct and desired suspension flow. Said geometry is carefully tested through numerous tests and trial-runs for a long time before the twin-wire press is placed in production. The geometry for the inlet box is hence fixed.
The fibre suspension is fed from a container, though gravity or with pump, via inlet pipes in to a distribution unit at the inlet box. When entering into the distribution unit the fibre suspension meets a first distribution sheet, whereby the fibre suspension is distributed over the entire width of the distribution unit in a slit and the fibre suspension is thereafter re-linked around the distribution sheet to the next slit and on to an outlet for further feeding to the wedge-shaped dewatering space between the wires.
Different kinds of disturbances to the production can occur in the process, whereby problems arise with the inlet box. In the inlet box formation of so called plugs, consisting of fibre suspension that is locally thickened resulting in that the fibre suspension stands still, can occur, resulting in that the inlet box has to be opened for cleaning. Malfunction on the propelling motor, system errors or an emergency halt of the machine can also led to occasional problems with the inlet box, which means that it has to be opened for control and occasional repair. It also happens that the inlet box needs to be opened for performing of normal maintenance on the inlet box.
A traditional inlet box consists of a number of metal sheets which are joined with a large number of bolted joints. Opening the inlet box to make room for cleaning or perform repairs on the inner of the inlet box, such as the slits, is time consuming and complicated. Large parts of the inlet box have to be disassembled.
Straightness of the metal sheets and the tolerances in general for the slits are precise, to get as good distribution of the fibre suspension as possible. Since the slits, which are formed from inner metal sheets in the inlet box, has an extensive spreading over large surfaces with few supports, the load on the slit sheets are relatively large. The slits, which are formed from the metal sheets, is therefore very sensitive for rapid increases in pressure. It is enough with a few bars overpressure to damage the metal sheets and make unacceptable changes in the slit tolerances. If the pressure gets far too high the inlet box could be damaged and in worst case collapse.
A conventional inlet box comprises one or more distribution units for adding of a fibre suspension to an inlet space at a dewatering press. Since the tolerances of the slits of each distribution unit are carefully determined, usually multiple distribution units is required for one inlet box at a dewatering press, since it otherwise becomes far too large surfaces and difficult to maintain the set tolerances in the slits.
In a conventional inlet box, comprising one or more distribution units, it is prior known to use pressure sensors, placed inside of respective distribution unit in the inlet box, which when sensing an exceeding pressure sends a signal to the control system of the press for shutting down the feeding of the fibre suspension to the inlet box.
However such a shut down happens via the control system with some delay. It is also known that there are explosive members connected to the control system, which are mounted in the distribution units in the inlet box so that the bolted joints can be blasted and the joined metal sheets separated, at a signal from the control system, so that the increased pressure inside of the distribution units in the inlet box can be removed, to in such a way prevent permanent damages to the inner parts of the distribution units of the inlet box. Naturally there are some damages to the bolted joints and outer metal sheets which require extensive repairs. Maintenance, control and repairs of a conventional distribution unit or inlet box resulting in long stoppage of production, which means lost production time, and hence a cost.
The purpose of the present invention is to at least partially eliminate the disadvantages associated with the state of the art mentioned above. A general purpose in accordance with the present invention is to achieve an improved distribution unit and an inlet box respectively, comprising one or more distribution units. More precise the purpose is to achieve a distribution unit and an inlet box respectively with longer life span and/or to achieve a simpler and faster maintenance in a dewatering press, such as a twin-wire press. Yet another purpose is, to a larger extent, to be able to even out the increased pressures in the distribution unit in the inlet box or to stop the feeding of the fibre suspension well in time before the risk of damages to the distribution unit or the inlet box arise. Furthermore, a purpose is to reduce the cost of repairs, control and maintenance of an inlet box for a dewatering press such as a twin-wire press.
This purpose is achieved with a distribution unit for adding of a fibre suspension to an inlet space at a dewatering press, in accordance with the present invention, which distribution unit comprise a distribution housing, which forms at least one distribution slit. The distribution slit is intended to be coupled to the inlet space of the dewatering press. The inlet box comprise at least one inlet member for adding of fibre suspension to the distribution slit, so that the fibre suspension passes through the distribution slit while spreading in the slit. The distribution housing is equipped with at least one opening to the distribution slit and a hatch belonging to the opening for shutting thereof. The hatch is hinged to the distribution housing in such a way so that it is pivotable relative to the distribution housing between a first position, in which the hatch seals the opening, and a second position, in which the hatch exposes the opening. The distribution unit is arranged to enable the hatch to move at least somewhat towards an open position under influence of a pressure, exceeding a predetermined value, in said distribution slit.
Repairs and inspection becomes less complicated in comparison to the construction in accordance with the traditional distribution units in an inlet box. In accordance with the present invention the cost of repairs and inspection is reduced, as well as assembling and replacing since the duration of the production halts can be considerably reduced, in comparison to the traditionally used distribution units in an inlet box. Damages to the distribution unit and the inlet box, respectively, can be avoided to a larger extent.
Thanks to the fact that the distribution unit is arranged to enable movement of the hatch to at least a somewhat more open position under the influence of a pressure, exceeding a predetermined value, in said distribution slit, the hatch can consequently be automatically opened in case of a increased pressure inside of the distribution unit, whereby damages to, among other things, the distribution slits in the distribution unit can be minimized to a larger extent.
According to one embodiment of the present invention, a hydraulic cylinder is arranged to move the hatch between said first and second positions.
The pressure in the hydraulic cylinder can be adapted to essentially correspond to the load that the pressure by the maximum allowed pressure in the distribution slit creates.
The present invention also relates to an inlet box for adding of a fibre suspension to an inlet space at a dewatering press, comprising one or more distribution units, which have been described above in accordance with the present invention.
The present invention also relates to a use of a distribution unit or an inlet box, which have been described above in accordance with the present invention, for a twin-wire press.
The present invention also relates to twin-wire press comprising an inlet box, which have been described above according to the invention.
Additional preferred features, advantages and preferred embodiments according to the invention are evident from the dependent claims, and also from the following description of examples of embodiments.
The present invention shall now be described in more detail by examples of embodiments, with reference to the accompanying drawings, without restricted interpretation of the invention thereof, where Fig. lA shows, schematically in a partial view, a cross-section of a distribution unit comprising a hatch, according to one embodiment of the present invention, in a first position with the hatch closed, Fig. 1B shows, schematically, in a partial view, a cross-section of the distribution unit, according to Fig. lA, in a second position with the hatch open, Fig. 1 C shows schematically, in a perspective view, a part of the distribution unit, according to Fig. lA-B, with the hatch in the open position, Fig 1D shows schematically, in a perspective view, a part of an inlet box, comprising a plurality of distribution units with a respective hatch, according to the distribution unit in Fig. lA-C, at an inlet part of a dewatering press, and Fig. 2 shows, schematically in an overview, a longitudinal cross-section through a twin-wire press according to an embodiment of the present invention that can comprise the inlet box with the embodiment shown in Fig. 1D.
In Fig. lA-C the distribution unit 1 is shown according to one embodiment of the present invention. The distribution unit 1 comprises a distribution housing 2 that forms at least a first distribution slit 4 and a second distribution slit 4'. The distribution unit 1 comprise at least one inlet member 6 for adding of fibre suspension to the distribution slit. The distribution housing 2 comprise an outlet opening 5 via which the fibre suspension passes after passage through the distribution slit 4, 4'. The fibre suspension passes through the distribution slit while spreading in the slit. The distribution housing 2 is equipped with at least one opening 8 to the distribution slit 4, 4' and a matching hatch 10 for sealing of the opening 8. The hatch 10 is hinged to the distribution housing 2, in a first pivot 11, so that the hatch is pivotable relative to the distribution housing 2 between a first position P 1, in which the hatch 10 seals the opening 8, and a second position P2, in which the hatch 10 exposes the opening 8. Consequently, easier and faster maintenance can be achieved in a dewatering press, such as a twin-wire press. Furthermore the increased pressures in the distribution unit 1 can to a larger extent be evened out. Feeding of the fibre suspension 1 can also be aborted well in time before risks of damages to the distribution unit arises. This can take place through that the hatch 10 is automatically opened, at least partially at a to large pressure inside of the distribution unit 1 and if it is decided that, by the process control system or an operator, there is risk of damages to the distribution unit 1 if the running is continued, the feeding of the fibre suspension is aborted. A pressure that should affect the opening of the hatch should be above a predetermined value, in said distribution slit 4, 4', before the hatch automatically can be opened.
The distribution unit 1 can comprise at least one hydraulic cylinder 12, arranged to move the hatch 10 between said first and second positions P 1, P2. The hydraulic cylinder can be arranged in front of the front end of the hatch 13. The cylinder 14 of the hydraulic cylinder 12 is preferably arranged to the distribution unit 1, at the underside 15 (see Fig. 1D) of the distribution unit. The outer end 16 of the piston bar 18 of the hydraulic cylinder is hinged to the hatch in a second pivot 20. As shown in Fig. lA-D, a link arm 22 can be fixedly fastened to the top of the hatch 24.
The link arm 22 is in its first end 26 hinged on the distribution housing 2 in the first pivot 11 and in the second end 28 is the link arm 22 arranged to the piston bar 18. As illustrated in Fig. lA-D, preferably two hydraulic cylinders 12 are arranged at a hatch 10 to move the hatch between the positions P 1, P2.
The pressure that is provided by the hydraulic fluid, such as oil, in the hydraulic cylinder 12 can be adapted to essentially correspond to the load that the maximum allowed pressure in the distribution slit 4, 4' creates. Calculation of the maximum allowed pressure in the distribution slits 4, 4' of the distribution units 1, with regards to a certain safety margin, can preferably be done at the construction, installation or assembly of the distribution units 1. An inlet box 30 preferably comprises several distribution units 1. The pressure in the distribution slits 4, 4' can preferably be measured with a pressure sensor arranged in a common inlet pipe (not shown), for adding of fibre suspension to the distribution slits 4, 4' at the distribution units 1, to which inlet pipe all of the inlet members 6 are connected. The hydraulic cylinder 12 can be provided with a pressure limiting member, such as a non-return valve.
The pressure in the hydraulic cylinder 12 can also be measured using a manometer.
Fig. 1C shows a distribution unit 1 comprising the hatch 10. As is clear from Fig. 1D, an inlet box 30 is shown, according to one embodiment of the present invention, with a number of distribution units 1 according to Fig. lA-C, comprising a plurality of hatches 10. The inlet box 30 is shown in Fig. 1D arranged at a dewatering press, such as a conventional twin-wire press 50. The twin-wire press 50 shows a dewatering space (not shown in Fig. 1D), an endless lower wire 54 and an endless upper wire 56.
The dewatering space has en inlet space 52, situated at and around the inlet box 30.
The distribution slit 4, 4'of respective distribution unit 1 at the inlet box 30 is intended to be connected to the inlet space 52 of the dewatering press and the inlet box 30 is hence arranged for adding of a fibre suspension to the inlet space 52 of the twin-wire press 50. Again with referral to Fig. lA-C, the fibre suspension is added via the distribution slit 4, 4' and de-linking takes place under spreading in at least one distribution slit 4 in the distribution housing 2. The fibre suspension passes after passage through the distribution slit 4, 4' via the outlet opening 5 at the distribution housing 2 to the inlet space in the dewatering press.
Fig. 2 shows schematically in an overview a longitudinal cross-section through a conventional twin-wire press 50 according to an embodiment of the present invention which can comprise the inlet box 30 with a plurality of distribution units 1 according to the embodiments shown in Fig. 1A-D. Corresponding conventional features and parts is denominated with the same reference numbers for the twin-wire press shown in Fig. 2 as for the distribution unit 1 and the inlet box 30, respectively, with the embodiments according to the present invention shown in Fig. lA-D.
The conventional twin-wire press 50 shows a dewatering space 58 with an inlet space 52 in the area at and around the inlet box 30. The fibre suspension to be dewatered is added from the inlet box 30 to the dewatering space 58 limited between the endless lower wire 54 and the endless upper wire 56 under movement of the wires 54, 56.
Perforated dewatering elements (not shown) have contact with the wires outside of the dewatering space. The filtrate flows through the wires 54, 56 from the dewatering space and is collected in outlet boxes 60, 62. The lower outlet box 60, arranged in a lower dewatering table, receives filtrate that flows from the dewatering space through the lower wire 54 and lower dewatering element, while the upper outlet box 62, arranged in an upper dewatering table, receives filtrate that flows from the dewatering space through the upper wire 56 and upper dewatering element.
The twin-wire press 50 comprises three lower rolls, one drive roll 100, one control roll 102 and one tension roll 104. The said endless lower wire 54 runs in a path around the lower rolls 100, 102, 104. In the corresponding manner said endless upper wire runs in a path around three upper rolls, one drive roll 106, one control roll 108 and one tension roll 110. Said upper outlet box 62 in the upper dewatering table that supports the upper wire 56, and said lower outlet box 60 in the lower dewatering table, that supports the lower wire 54, forms the dewatering space 58 between the wires 54, 56.
The twin-wire press comprises one common roll arrangement 112 according to the state of the art.
In operation of the twin-wire press 50 according to Fig. 2, the transportation of the wires 54, 56 takes place under rotation of the rolls 100-110. The fibre suspension to be dewatered is fed to the oblong dewatering space 58 via the inlet box 30 at the inlet space 52 thereof. The fibre suspension is dewatered in the dewatering space 58 under movement of the wires, so that a filtrate flow from the dewatering space 58 through the wires 54, 56 and the perforated dewatering elements is formed. The filtrate that flows from the dewatering space through the wires is collected in the outlet boxes 60, 62.
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Dewatering presses for dewatering of a fibre suspension and forming of a continuous web thereof are previously known. One example of a known dewatering press is a twin-wire press. Dewatering of the pulp is usually done from an inlet pulp concentration of 3-8 percentages by weight to an outlet pulp concentration of percentages by weight. According to the state of the art, such twin-wire presses comprises lower rolls, an endless lower wire running in a path around the lower rolls, upper rolls, and an endless upper wire running in a path around the upper rolls. The two wires co-operate with each other along dewatering sections of said paths, in which the wires forms a wedge-shaped dewatering space for the fibre suspension between each other. During displacement of the wires along said dewatering sections, the wires thus successively compresses the fibre suspension in the wedge-shaped space, whereby the fibre suspension is initially pressed and dewatered and formed to a continuous fibre web between the wires.
An inlet box provides for supply of fibre suspension to the wedge-shaped dewatering space between the wires. The known twin-wire press further comprises two dewatering tables supporti:ng the respective wire in said dewatering sections of the path, such that the wedge-shaped dewatering space is formed between the wires, and a roll arrangement situated after the dewatering tables, as seen in the direction of movement of the wires, for finally pressing and dewatering of the fibre web between the wires, so that the fibre web will get a desired dryness. Alongside the longitudinal direction of the wires, in the wedge-shaped dewatering space, there are perforated dewatering elements that are arranged against the wires outside the dewatering space.
Formed filtrate flows through the wires and the perforated dewatering elements and is lead away to upper and lower outlet boxes, respectively, arranged at the dewatering tables.
The upper and lower outlet box, respectively, may be divided into several chambers whereby a filtrate that flows through the upper and lower dewatering elements, respectively, may be divided into partial filtrate in two or more chambers in the respective outlet box.
In the traditional twin-wire press the geometry for the inlet box, for adding of the fibre suspension to the wedge-shaped dewatering space between the wires, is very difficult to set to obtain correct and desired suspension flow. Said geometry is carefully tested through numerous tests and trial-runs for a long time before the twin-wire press is placed in production. The geometry for the inlet box is hence fixed.
The fibre suspension is fed from a container, though gravity or with pump, via inlet pipes in to a distribution unit at the inlet box. When entering into the distribution unit the fibre suspension meets a first distribution sheet, whereby the fibre suspension is distributed over the entire width of the distribution unit in a slit and the fibre suspension is thereafter re-linked around the distribution sheet to the next slit and on to an outlet for further feeding to the wedge-shaped dewatering space between the wires.
Different kinds of disturbances to the production can occur in the process, whereby problems arise with the inlet box. In the inlet box formation of so called plugs, consisting of fibre suspension that is locally thickened resulting in that the fibre suspension stands still, can occur, resulting in that the inlet box has to be opened for cleaning. Malfunction on the propelling motor, system errors or an emergency halt of the machine can also led to occasional problems with the inlet box, which means that it has to be opened for control and occasional repair. It also happens that the inlet box needs to be opened for performing of normal maintenance on the inlet box.
A traditional inlet box consists of a number of metal sheets which are joined with a large number of bolted joints. Opening the inlet box to make room for cleaning or perform repairs on the inner of the inlet box, such as the slits, is time consuming and complicated. Large parts of the inlet box have to be disassembled.
Straightness of the metal sheets and the tolerances in general for the slits are precise, to get as good distribution of the fibre suspension as possible. Since the slits, which are formed from inner metal sheets in the inlet box, has an extensive spreading over large surfaces with few supports, the load on the slit sheets are relatively large. The slits, which are formed from the metal sheets, is therefore very sensitive for rapid increases in pressure. It is enough with a few bars overpressure to damage the metal sheets and make unacceptable changes in the slit tolerances. If the pressure gets far too high the inlet box could be damaged and in worst case collapse.
A conventional inlet box comprises one or more distribution units for adding of a fibre suspension to an inlet space at a dewatering press. Since the tolerances of the slits of each distribution unit are carefully determined, usually multiple distribution units is required for one inlet box at a dewatering press, since it otherwise becomes far too large surfaces and difficult to maintain the set tolerances in the slits.
In a conventional inlet box, comprising one or more distribution units, it is prior known to use pressure sensors, placed inside of respective distribution unit in the inlet box, which when sensing an exceeding pressure sends a signal to the control system of the press for shutting down the feeding of the fibre suspension to the inlet box.
However such a shut down happens via the control system with some delay. It is also known that there are explosive members connected to the control system, which are mounted in the distribution units in the inlet box so that the bolted joints can be blasted and the joined metal sheets separated, at a signal from the control system, so that the increased pressure inside of the distribution units in the inlet box can be removed, to in such a way prevent permanent damages to the inner parts of the distribution units of the inlet box. Naturally there are some damages to the bolted joints and outer metal sheets which require extensive repairs. Maintenance, control and repairs of a conventional distribution unit or inlet box resulting in long stoppage of production, which means lost production time, and hence a cost.
The purpose of the present invention is to at least partially eliminate the disadvantages associated with the state of the art mentioned above. A general purpose in accordance with the present invention is to achieve an improved distribution unit and an inlet box respectively, comprising one or more distribution units. More precise the purpose is to achieve a distribution unit and an inlet box respectively with longer life span and/or to achieve a simpler and faster maintenance in a dewatering press, such as a twin-wire press. Yet another purpose is, to a larger extent, to be able to even out the increased pressures in the distribution unit in the inlet box or to stop the feeding of the fibre suspension well in time before the risk of damages to the distribution unit or the inlet box arise. Furthermore, a purpose is to reduce the cost of repairs, control and maintenance of an inlet box for a dewatering press such as a twin-wire press.
This purpose is achieved with a distribution unit for adding of a fibre suspension to an inlet space at a dewatering press, in accordance with the present invention, which distribution unit comprise a distribution housing, which forms at least one distribution slit. The distribution slit is intended to be coupled to the inlet space of the dewatering press. The inlet box comprise at least one inlet member for adding of fibre suspension to the distribution slit, so that the fibre suspension passes through the distribution slit while spreading in the slit. The distribution housing is equipped with at least one opening to the distribution slit and a hatch belonging to the opening for shutting thereof. The hatch is hinged to the distribution housing in such a way so that it is pivotable relative to the distribution housing between a first position, in which the hatch seals the opening, and a second position, in which the hatch exposes the opening. The distribution unit is arranged to enable the hatch to move at least somewhat towards an open position under influence of a pressure, exceeding a predetermined value, in said distribution slit.
Repairs and inspection becomes less complicated in comparison to the construction in accordance with the traditional distribution units in an inlet box. In accordance with the present invention the cost of repairs and inspection is reduced, as well as assembling and replacing since the duration of the production halts can be considerably reduced, in comparison to the traditionally used distribution units in an inlet box. Damages to the distribution unit and the inlet box, respectively, can be avoided to a larger extent.
Thanks to the fact that the distribution unit is arranged to enable movement of the hatch to at least a somewhat more open position under the influence of a pressure, exceeding a predetermined value, in said distribution slit, the hatch can consequently be automatically opened in case of a increased pressure inside of the distribution unit, whereby damages to, among other things, the distribution slits in the distribution unit can be minimized to a larger extent.
According to one embodiment of the present invention, a hydraulic cylinder is arranged to move the hatch between said first and second positions.
The pressure in the hydraulic cylinder can be adapted to essentially correspond to the load that the pressure by the maximum allowed pressure in the distribution slit creates.
The present invention also relates to an inlet box for adding of a fibre suspension to an inlet space at a dewatering press, comprising one or more distribution units, which have been described above in accordance with the present invention.
The present invention also relates to a use of a distribution unit or an inlet box, which have been described above in accordance with the present invention, for a twin-wire press.
The present invention also relates to twin-wire press comprising an inlet box, which have been described above according to the invention.
Additional preferred features, advantages and preferred embodiments according to the invention are evident from the dependent claims, and also from the following description of examples of embodiments.
The present invention shall now be described in more detail by examples of embodiments, with reference to the accompanying drawings, without restricted interpretation of the invention thereof, where Fig. lA shows, schematically in a partial view, a cross-section of a distribution unit comprising a hatch, according to one embodiment of the present invention, in a first position with the hatch closed, Fig. 1B shows, schematically, in a partial view, a cross-section of the distribution unit, according to Fig. lA, in a second position with the hatch open, Fig. 1 C shows schematically, in a perspective view, a part of the distribution unit, according to Fig. lA-B, with the hatch in the open position, Fig 1D shows schematically, in a perspective view, a part of an inlet box, comprising a plurality of distribution units with a respective hatch, according to the distribution unit in Fig. lA-C, at an inlet part of a dewatering press, and Fig. 2 shows, schematically in an overview, a longitudinal cross-section through a twin-wire press according to an embodiment of the present invention that can comprise the inlet box with the embodiment shown in Fig. 1D.
In Fig. lA-C the distribution unit 1 is shown according to one embodiment of the present invention. The distribution unit 1 comprises a distribution housing 2 that forms at least a first distribution slit 4 and a second distribution slit 4'. The distribution unit 1 comprise at least one inlet member 6 for adding of fibre suspension to the distribution slit. The distribution housing 2 comprise an outlet opening 5 via which the fibre suspension passes after passage through the distribution slit 4, 4'. The fibre suspension passes through the distribution slit while spreading in the slit. The distribution housing 2 is equipped with at least one opening 8 to the distribution slit 4, 4' and a matching hatch 10 for sealing of the opening 8. The hatch 10 is hinged to the distribution housing 2, in a first pivot 11, so that the hatch is pivotable relative to the distribution housing 2 between a first position P 1, in which the hatch 10 seals the opening 8, and a second position P2, in which the hatch 10 exposes the opening 8. Consequently, easier and faster maintenance can be achieved in a dewatering press, such as a twin-wire press. Furthermore the increased pressures in the distribution unit 1 can to a larger extent be evened out. Feeding of the fibre suspension 1 can also be aborted well in time before risks of damages to the distribution unit arises. This can take place through that the hatch 10 is automatically opened, at least partially at a to large pressure inside of the distribution unit 1 and if it is decided that, by the process control system or an operator, there is risk of damages to the distribution unit 1 if the running is continued, the feeding of the fibre suspension is aborted. A pressure that should affect the opening of the hatch should be above a predetermined value, in said distribution slit 4, 4', before the hatch automatically can be opened.
The distribution unit 1 can comprise at least one hydraulic cylinder 12, arranged to move the hatch 10 between said first and second positions P 1, P2. The hydraulic cylinder can be arranged in front of the front end of the hatch 13. The cylinder 14 of the hydraulic cylinder 12 is preferably arranged to the distribution unit 1, at the underside 15 (see Fig. 1D) of the distribution unit. The outer end 16 of the piston bar 18 of the hydraulic cylinder is hinged to the hatch in a second pivot 20. As shown in Fig. lA-D, a link arm 22 can be fixedly fastened to the top of the hatch 24.
The link arm 22 is in its first end 26 hinged on the distribution housing 2 in the first pivot 11 and in the second end 28 is the link arm 22 arranged to the piston bar 18. As illustrated in Fig. lA-D, preferably two hydraulic cylinders 12 are arranged at a hatch 10 to move the hatch between the positions P 1, P2.
The pressure that is provided by the hydraulic fluid, such as oil, in the hydraulic cylinder 12 can be adapted to essentially correspond to the load that the maximum allowed pressure in the distribution slit 4, 4' creates. Calculation of the maximum allowed pressure in the distribution slits 4, 4' of the distribution units 1, with regards to a certain safety margin, can preferably be done at the construction, installation or assembly of the distribution units 1. An inlet box 30 preferably comprises several distribution units 1. The pressure in the distribution slits 4, 4' can preferably be measured with a pressure sensor arranged in a common inlet pipe (not shown), for adding of fibre suspension to the distribution slits 4, 4' at the distribution units 1, to which inlet pipe all of the inlet members 6 are connected. The hydraulic cylinder 12 can be provided with a pressure limiting member, such as a non-return valve.
The pressure in the hydraulic cylinder 12 can also be measured using a manometer.
Fig. 1C shows a distribution unit 1 comprising the hatch 10. As is clear from Fig. 1D, an inlet box 30 is shown, according to one embodiment of the present invention, with a number of distribution units 1 according to Fig. lA-C, comprising a plurality of hatches 10. The inlet box 30 is shown in Fig. 1D arranged at a dewatering press, such as a conventional twin-wire press 50. The twin-wire press 50 shows a dewatering space (not shown in Fig. 1D), an endless lower wire 54 and an endless upper wire 56.
The dewatering space has en inlet space 52, situated at and around the inlet box 30.
The distribution slit 4, 4'of respective distribution unit 1 at the inlet box 30 is intended to be connected to the inlet space 52 of the dewatering press and the inlet box 30 is hence arranged for adding of a fibre suspension to the inlet space 52 of the twin-wire press 50. Again with referral to Fig. lA-C, the fibre suspension is added via the distribution slit 4, 4' and de-linking takes place under spreading in at least one distribution slit 4 in the distribution housing 2. The fibre suspension passes after passage through the distribution slit 4, 4' via the outlet opening 5 at the distribution housing 2 to the inlet space in the dewatering press.
Fig. 2 shows schematically in an overview a longitudinal cross-section through a conventional twin-wire press 50 according to an embodiment of the present invention which can comprise the inlet box 30 with a plurality of distribution units 1 according to the embodiments shown in Fig. 1A-D. Corresponding conventional features and parts is denominated with the same reference numbers for the twin-wire press shown in Fig. 2 as for the distribution unit 1 and the inlet box 30, respectively, with the embodiments according to the present invention shown in Fig. lA-D.
The conventional twin-wire press 50 shows a dewatering space 58 with an inlet space 52 in the area at and around the inlet box 30. The fibre suspension to be dewatered is added from the inlet box 30 to the dewatering space 58 limited between the endless lower wire 54 and the endless upper wire 56 under movement of the wires 54, 56.
Perforated dewatering elements (not shown) have contact with the wires outside of the dewatering space. The filtrate flows through the wires 54, 56 from the dewatering space and is collected in outlet boxes 60, 62. The lower outlet box 60, arranged in a lower dewatering table, receives filtrate that flows from the dewatering space through the lower wire 54 and lower dewatering element, while the upper outlet box 62, arranged in an upper dewatering table, receives filtrate that flows from the dewatering space through the upper wire 56 and upper dewatering element.
The twin-wire press 50 comprises three lower rolls, one drive roll 100, one control roll 102 and one tension roll 104. The said endless lower wire 54 runs in a path around the lower rolls 100, 102, 104. In the corresponding manner said endless upper wire runs in a path around three upper rolls, one drive roll 106, one control roll 108 and one tension roll 110. Said upper outlet box 62 in the upper dewatering table that supports the upper wire 56, and said lower outlet box 60 in the lower dewatering table, that supports the lower wire 54, forms the dewatering space 58 between the wires 54, 56.
The twin-wire press comprises one common roll arrangement 112 according to the state of the art.
In operation of the twin-wire press 50 according to Fig. 2, the transportation of the wires 54, 56 takes place under rotation of the rolls 100-110. The fibre suspension to be dewatered is fed to the oblong dewatering space 58 via the inlet box 30 at the inlet space 52 thereof. The fibre suspension is dewatered in the dewatering space 58 under movement of the wires, so that a filtrate flow from the dewatering space 58 through the wires 54, 56 and the perforated dewatering elements is formed. The filtrate that flows from the dewatering space through the wires is collected in the outlet boxes 60, 62.
-------------
Claims (8)
1. Distribution unit (1) for adding of a fibre suspension to an inlet space (52) at a dewatering press, which distribution unit comprise a distribution housing (2), that forms at least one distribution slit (4, 4'), which distribution slit is intended to be connected to the inlet space of the dewatering press (52), and at least one inlet member (6) for adding of the fibre suspension to the distribution slit, so that the fibre suspension passes through the distribution slit while spreading in the slit, that the distribution housing (2) is equipped with at least one opening (8) to the distribution slit (4, 4') and a matching hatch (10) for sealing of the opening (8), and that the hatch (10) is hinged in such a way to the distribution housing (2) so that it is pivotable relative to the distribution housing (2) between a first position (P1), in which the hatch (10) seals the opening (8), and a second position (P2), in which the hatch (10) exposes the opening (8), characterized in that it is arranged to allow the hatch (10) to be moved at least somewhat towards the open position under the influence of a pressure, exceeding a predetermined value, in said distribution slit (4, 4').
2. Distribution unit (1) according to claim 1, characterized in that at least one hydraulic cylinder (12) is arranged to move the hatch (10) between said first and second positions (P1, P2).
3. Distribution unit (1) according to claim 2, characterized in that the pressure in the hydraulic cylinder (12) is adapted to essentially correspond to the load that the maximum allowed pressure in the distribution slit (4, 4') creates.
4. Distribution unit (1) according to claim 2 or claim 3, characterized in that the hydraulic cylinder (12) is equipped with a pressure limiting device.
5. Inlet box (30) for adding of a fibre suspension to an inlet space at a dewatering press, comprising one or more distribution units (1) according to any of the preceding claims 1-4.
6. Inlet box according to claim 5, characterized in that it comprises more distribution units (1), where the pressure in the distribution slits (4, 4') is measured with a pressure sensor arranged in a common inlet pipe, for adding of fibre suspension to the distribution slits (4, 4') with the distribution units (1), to which inlet pipe all of the inlet members (6) are connected.
7. Use of a distribution unit (1) or an inlet box (30) according to any of the preceding claims 1-6, for a twin-wire press (50).
8. Twin-wire press (50) for dewatering of a fibre suspension comprising lower rolls (100, 102, 104), an endless lower wire (54), upper rolls (106, 108, 110) and an endless upper wire (56), characterized in that it comprises an inlet box (30) according to any of the claims 5-6.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE0700530-9 | 2007-03-01 | ||
| SE0700530A SE530972C2 (en) | 2007-03-01 | 2007-03-01 | Distribution unit in an inlet box for a dewatering press and its use |
| PCT/SE2008/000143 WO2008105706A1 (en) | 2007-03-01 | 2008-02-21 | Distribution unit in an inlet box for a dewatering press |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2676660A1 true CA2676660A1 (en) | 2008-09-04 |
Family
ID=39721481
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002676660A Abandoned CA2676660A1 (en) | 2007-03-01 | 2008-02-21 | Distribution unit in an inlet box for a dewatering press |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US20100206508A1 (en) |
| EP (1) | EP2126201A4 (en) |
| CA (1) | CA2676660A1 (en) |
| SE (1) | SE530972C2 (en) |
| WO (1) | WO2008105706A1 (en) |
Family Cites Families (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3220919A (en) * | 1962-10-05 | 1965-11-30 | Beloit Corp | Shaped rod turbulence generators for use in a flowing stream of paper pulp |
| US3247049A (en) * | 1962-10-08 | 1966-04-19 | Beloit Corp | Pressure relief valve for papermaking machine headbox |
| US3384537A (en) * | 1965-04-27 | 1968-05-21 | Sandy Hill Corp | Multi-layer papermaking apparatus |
| CH564639A5 (en) * | 1973-04-17 | 1975-07-31 | Escher Wyss Gmbh | |
| FI57281C (en) * | 1976-10-05 | 1980-07-10 | Valmet Oy | DAEMPNINGSSYSTEM FOER TRYCKVARIATIONER I MASSASUSPENSIONSSTROEMNINGEN I DEN HYDRAULISKA INLOPPSLAODAN HOS EN PAPPERSMASKIN |
| FI771209A (en) * | 1977-04-15 | 1978-10-16 | Valmet Oy | PAPER MUSHROOMS FOR THE PULP OF THE PULP MUSCLE |
| US4141789A (en) * | 1977-11-22 | 1979-02-27 | Beloit Corporation | Headbox having pivoted bridging cover |
| FI84920C (en) * | 1988-05-27 | 1992-02-10 | Valmet Ahlstroem Inc | Hydraulic inlet box in paper or cardboard machine |
| FI79363C (en) * | 1988-09-26 | 1989-12-11 | Valmet Paper Machinery Inc | FOERFARANDE OCH ANORDNING I INLOPPSLAODAN AV EN PAPPERSMASKIN FOER ATT BEHAERSKA FOERDELNINGEN I PAPPERSBANANS FIBERORIENTERING. |
| DE9416731U1 (en) * | 1994-10-18 | 1995-01-12 | Sulzer-Escher Wyss Gmbh, 88212 Ravensburg | Headbox for a paper machine |
| US5783045A (en) * | 1996-05-06 | 1998-07-21 | Beloit Technologies, Inc. | Pulp and linerboard former with improved dewatering |
| AT404847B (en) * | 1996-06-27 | 1999-03-25 | Andritz Patentverwaltung | METHOD AND DEVICE FOR DISTRIBUTING A, IN PARTICULAR MEDIUM-CONSISTENT, FIBER FIBER SUSPENSION |
| SE9902308L (en) * | 1999-06-18 | 2000-05-29 | Kvaerner Pulping Tech | Sealing means in a device for dewatering pulp |
| FI19991793A (en) * | 1999-08-23 | 2001-02-24 | Andritz Ahlstrom Oy | Method for controlling the operation of an inflow system of a paper machine or the like |
| US7585392B2 (en) * | 2006-10-10 | 2009-09-08 | Georgia-Pacific Consumer Products Lp | Method of producing absorbent sheet with increased wet/dry CD tensile ratio |
-
2007
- 2007-03-01 SE SE0700530A patent/SE530972C2/en not_active IP Right Cessation
-
2008
- 2008-02-21 US US12/529,074 patent/US20100206508A1/en not_active Abandoned
- 2008-02-21 EP EP08712730.4A patent/EP2126201A4/en not_active Withdrawn
- 2008-02-21 CA CA002676660A patent/CA2676660A1/en not_active Abandoned
- 2008-02-21 WO PCT/SE2008/000143 patent/WO2008105706A1/en active Application Filing
Also Published As
| Publication number | Publication date |
|---|---|
| SE0700530L (en) | 2008-09-02 |
| US20100206508A1 (en) | 2010-08-19 |
| WO2008105706A1 (en) | 2008-09-04 |
| EP2126201A4 (en) | 2013-04-10 |
| EP2126201A1 (en) | 2009-12-02 |
| SE530972C2 (en) | 2008-11-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |
Effective date: 20140221 |