US3622450A - Papermaking flow box - Google Patents

Papermaking flow box Download PDF

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Publication number
US3622450A
US3622450A US830421A US3622450DA US3622450A US 3622450 A US3622450 A US 3622450A US 830421 A US830421 A US 830421A US 3622450D A US3622450D A US 3622450DA US 3622450 A US3622450 A US 3622450A
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United States
Prior art keywords
stock
flow box
outlet
chamber
flow
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Expired - Lifetime
Application number
US830421A
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English (en)
Inventor
Brian William Attwood
Harold George Curry
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St Annes Board Mill Co Ltd
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St Annes Board Mill Co Ltd
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Filing date
Publication date
Application filed by St Annes Board Mill Co Ltd filed Critical St Annes Board Mill Co Ltd
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Publication of US3622450A publication Critical patent/US3622450A/en
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    • 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
    • D21F1/02—Head boxes of Fourdrinier machines
    • D21F1/026—Details of the turbulence section

Definitions

  • the explosion chamber creates turbulence and mixing of stock flowing therethrough without streaming thereof.
  • SHEET 3 [IF 3 PAPERMAKING FLOW BOX This invention relates to flow boxes for machines for dewatering watery pulp to form a sheet e.g. in the manufacture of board or paper and is an improvement in or modification of the invention disclosed and claimed in our copending British application No. 3,8983/66.
  • a flow box comprising an enclosed explosion chamber having a stock inlet and a stock outlet each of overall cross section less than the transverse cross section of the explosion chamber at the inlet and the outlet respectively, and an imperforate baffle plate disposed transversely to the flow paths of stock inlet and outlet, and dividing the chamber into two successive flow portions with a restricted passage therebetween.
  • explosion chamber is known in the art to mean a chamber in which a high-speed stream of stock is very quickly changed in speed and direction of fiow by rapid expansion and/or impingement on an obstruction or baffle plate whereby the stream disintegrates or explodes thereby causing mixing and deflocculation of the stock by turbulence generation.
  • a flow box for a paper, board or similar fibrous webmaking machine comprising an enclosed explosion chamber having a stock inlet and an opposed stock outlet each of overall cross section less than the transverse cross section of the explosion chamber at the inlet and outlet respectively, an imperforate bafile plate disposed transversely of the inlet and outlet and dividing the chamber into two successive flow portions with two restricted passages therebetween around the transversely opposed edges of the plate.
  • the present invention provides a development of the basic flow box of our prior case in that two flowpaths are provided around opposed edges of the baffie.
  • the stock flowing around these paths must meet to pass through the common exit from the flow box. Since the stock fiows around the opposed edges of the plate or baffie, the two stock streams collide at the exit, thus causing further turbulence and mixing and ensuring that no streamting" of the stock occurs.
  • streaming is meant occurrence of high spots or areas of excess stock compared with the remainder of the stock jet across the width of the flow box. Such areas result in productionof a sheet having an uneven surface.
  • the baffle plate comprises two planar portions one of which is disposed obliquely with respect to the other, the plate being arranged in the flow box with said planar portions inclined to the flow path of stock through said inlet.
  • the chamber may be divided by an imperforate well extending from between said inlets to said baffle.
  • the flow box is rectangular in cross section, said inlet or inlets and outlet being disposed in one opposed pair of walls, and the baffle defining the restricted flow passages with the other pair of opposed walls thereof.
  • the highly turbulent, deflocculated and well-mixed stock is ejected immediately from the flow box onto the machine wire with the minimum possible delay, by a flow path ensuring that, from the chamber to the wire, no slowing down of the stock occurs which would promote reclotting.
  • the outlet to the flow box itself can constitute the slice.
  • a very short nondivergent passage may be provided.
  • the ratio of outlet area to inlet area should be from 0.421 to 4.0:1 preferably from 1:1 to 3: 1.
  • the flow box may however be used with lower consistency stock e.g., in paper of tissue manufacture.
  • stocks of 0.1-1.0 percent solid content may be usefully used with such a headbox.
  • the inlet to the explosion chamber is provided by a plurality of ports communicating with a plurality of tubes through which stock is fed to the chamber from a headbox.
  • the flow box is preferably used on at least the second and any subsequent plies, but may also be used on the first ply.
  • FIG. 1 is a diagrammatic side elevation of part of a boardmaking machine including a flow box according to the present invention.
  • FIG. 2 is a front elevation of the flow box shown in FIG. 1,
  • FIGS. 3 to 7 are side elevations of alternative forms of flow box according to the present invention.
  • FIGS. 1 and thereof there is shown the second ply stage of an lnverform (Registered Trade Mark) boardmaking machine.
  • the main wire 10 containing a dewatered web from the first ply stage passes over a table roll 11 of the second ply stage.
  • An upper wire 13 of the second ply stage passes around a forming roll 14 and converges on wire 10 to define therebetween a convergent gap 20 within which stock is initially dewatered to form the second ply of the web.
  • a flow box 30 comprising a header tank 31 and an explosion chamber 32.
  • Stock is pumped into header tank 31 through a tapered crossflow pipe 33 of decreasing cross section in its direction of fiow.
  • Stock pumped through this pipe is fed into header tank 31 through a plurality of ducts spaced across the machine, only one such duct, 34 being shown in FIG. 1.
  • the tank 31 includes a baffie plate 35 disposed in the flowpath of incoming stock from pipes 34.
  • the stock impinging on plate 35 will be disintegrated, causing mixing and turbulence.
  • the stock flows around the opposed upper and lower edges of the plate 35 through the narrow passages 36, 37 and through two parallel sets of shear flow tubes 38, 39 in the lower end of the chamber.
  • pipes 34 are narrow compared with the cross section of tank 31, and thus turbulence is effected as stock enters the tank merely by the divergence of the flow.
  • a standpipe 40 communicating with the upper wall of the tank 31 maintains a head of stock sufficient for efficient running of the flow box and ensures that tank 31 can be maintained full, thus avoiding crusting and aeration of the stock.
  • Stock leaving header tank 31 flows to the vortex or explosion chamber 32 via the shear fiow narrow bore tubes 38, 39.
  • the tubes in each set are disposed in one plane and are parallel to one another. However the tubes in one set could be inclined relative to those in the other set to provide a skew arrangement.
  • crossfiow of stock is achieved which creates turbulence and destroys any irregularities in stock consistency across the width of the machine (i.e. destroys streaming of the stock).
  • regulation of web weight is achieved across the machine width preventing high spots and maintaining a consistent board density.
  • the chamber 32 is substantially rectangular, the tubes 38, 39 entering through the upper wall thereof and an exit 50 being disposed in the opposed wall. Disposed between these opposed walls is an imperforate baffle 51.
  • the baffle com prises two planar plates 52, 53 inclined to one another and extending across the full width of the explosion chamber 32 (as seen in FIG. 2). As well as being inclined to one another, plates 52, 53 are disposed obliquely relative to the incoming stock flow through tubes 38, 39.
  • An imperforate wall 54 extends from the upper wall of the explosion chamber (between the pipes 38, 39) to the meeting line between plates 52, 53, thus dividing and separating the incoming stock flows.
  • each half of the explosion chamber 32 is divided into two successive flow areas with a restricted passage therebetween, the passage being defined between the free edges of the plates 52, 53 and the walls of the chamber 32.
  • the flow areas also define divergent/convergent/divergent/convergent flowpaths for the stock from inlets 38, 39 to the outlet 50.
  • Passage 55 is defined between convergent plates which thus do not allow any decrease in velocity of the high-speed stock, but eject it, as a high-speed jet of homogeneous, suspended entangled comoving deflocculated fibrous suspension into the convergent gap 20 of the board machine through slice 56.
  • the passage 55 can be parallel sided without allowing any decrease in stock velocity and thus maintaining the high-speed deflocculated jet required.
  • the plates defining passage 55 are made relatively adjustable, e.g., by screws 57 on the upper plate for varying the size of slice 56.
  • the slice could be one-half inch high, the passage 55 being 6 inch long.
  • a very narrow and short exit is provided from the explosion chamber to ensure that work done in the chamber to provide turbulent stock is not lost in directing the stock onto the machine.
  • these may be rounded using corner inserts or by suitably reshaping the corners of the chamber while preferably retaining the generally rectangular cross section.
  • the relative dimensions of the flow box illustrated will be maintained across the machine for any width of machine.
  • the passage 58 will be 6 inches long, 1 inch deep at inlet and one-half inch at its outlet (the slice 56) corresponding dimensions for the explosion chamber 32 could be 4 inches high by 6 inches long with, say, seven tubes 38, 39 per 20 inch width of machine, each tube being of 1 inch internal diameter.
  • inletzoutlet ratio of chamber 135 is of the order of 2: 1. Experiments show that this ratio should be in the range of 0.4:l to 4:1 for good results.
  • FIGS. 3 to 7 variations on the basic idea illustrated in FIGS. 1 and 2 are shown in these figures.
  • FIGS. 3 to all employ the same header tank, tubes 38, 39 and explosion chamber 32 as described above with reference to FIGS. 1 and 2.
  • the baffle plate while employing a similar portion 54, has a single planar plate 60 disposed at 90to partition 54 and inlet tubes 38, 39.
  • stock flows around the plate 50 and two streams of stock meet at exit 50.
  • a single splash plate 61 is disposed obliquely with respect to the outlet flow path to deflect stock onto machine wire 10.
  • a plate 63 adjustable laterally of exit 50 by screws 64 controls the size of the slice which is provided by exit 50.
  • the baffle plates 52, 53 are provided as in FIG. 1. However difi'erent exit passages are provided.
  • the exit passage comprises a linear section 65 followed by an obliquely disposed plate 66 directing stock onto wire I0.
  • An adjustable plate 67 adjusted by a screw 68 defines with plate 66 an adjustable slice 70.
  • the exit is provided by a splash plate 71 similar to that disclosed in FIG. 3. Again a plate 72 adjusted by a screw 73 provides an adjustable slice coincident with exit 50.
  • FIGS. 6 and 7 the explosion chamber 32 and supply of stock thereto through tubes 38, 39 is similar to that for FIG. 1.
  • FIGS. demonstrate how the explosion chamber can be tilted relative to machine wire 10, the exit passage from the explosion chamber being modified accordingly.
  • the exit passage is cranked and nonadjustable.
  • the final lip of the slice 81 could be made adjustable.
  • the outlet passage 82 is linear, and horizontal ending in a convergent section 83 providing slice 84.
  • header tank 31 may be pressurized, open to atmosphere or under vacuum.
  • the size, shape and orientation of the explosion chamber 32 may be varied to suit the stock and machine requirements.
  • the machine on which the flow box is employed can be of many designs.
  • the two-wire Inverform arrangement shown in GB. Pat. No. 859083 may be used, this being a common arrangement in present day Inverform machines.
  • header tank 31 a second inlet (indicated in broken lines in FIG. 1) could be employed.
  • the pipes 38, 39 could be skew to one another (as shown in FIGS. 6 and 7) and also the tubes in any one set could be skew to one another in that set.
  • the jet so formed is directed into the convergent forming gap 20 with as little delay as possible. Since the stock may tend to reflocculate within a very short distancea matter of inches only-it is advisable to dewater the stock as quickly possible after it leaves the slice or shear channel. Thus the spacing between the slice and the gap 20 is kept at a minimum.
  • the most useful application of these flow boxes is on multiply paper and board machines, e.g., Inverform machines. Due to their compact nature they take up very little space and considerable saving in overall machine length is achieved. Being simple and compact they are also cheaper to make and install, with less problem of support. However it should also be borne in mind that these advantages are achieved without decreasing the quality of the stock generated.
  • a flow box in combination with a paper, board or similar fibrous webmaking machine comprising,
  • baffle plate having oppositely extending free ends
  • first and second restricted passages defined by the spacing between said free ends of said baffle plate and two walls of the chamber.
  • a flow box in combination with a paper, board or similar fibrous webmaking machine comprising,
  • baffle plate having oppositely extending free ends, disposed transversely of the wall including the inlets and the wall including the outlet, for dividing the chamber into two successive sub chambers interconnected by first and second restricted passages defined by the spacing between said free 'ends of the baffle plate and two walls of the chamber.
  • bafile plate comprises two planar plates inclined to each other and individually opposed to a respective one of the two inlets.
  • a flow box as claimed in claim 1 wherein the stock outlet defining means comprises means defining a nondivergent passage leading to an exit slice from the flow box for ejecting stock onto a machine wire.
  • a flow box as claimed in claim 1 wherein the stock outlet defining means comprises means defining a slit in a wall of the chamber, the slit further providing an exit slice from the flow box for ejecting stock into a machine wire, said flow box further comprising a plate disposed obliquely with respect to the flow path at the outlet for deflecting stock directly onto the machine wire.
  • a flow box as claimed in claim 2 further comprising an imperforate wall extending from between said inlet defining means to said bafile late.
  • a flow box as claimed in claim 1 wherein the defining means comprises a plurality of tubes spaced across the width of the chamber.
  • a flow box as claimed in claim 9 wherein the plurality of tubes comprises two sets of inlet tubes communicating with a header tank on opposed sides of a planar partition generally parallel to the flow path through said tubes, the inlet to said header tank being normal to said partition.
  • a flow box as claimed in claim 10 wherein the partition is spaced from the walls of the header tank at opposed edges thereof to provide flow passages around either edge of the partition between the opposed sides thereof.

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US830421A 1968-07-04 1969-06-04 Papermaking flow box Expired - Lifetime US3622450A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3197468 1968-07-04

Publications (1)

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US3622450A true US3622450A (en) 1971-11-23

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US830421A Expired - Lifetime US3622450A (en) 1968-07-04 1969-06-04 Papermaking flow box

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US (1) US3622450A (de)
DE (1) DE1930795B2 (de)
FR (1) FR2012275A6 (de)
GB (1) GB1228385A (de)
PL (1) PL83181B3 (de)
SE (1) SE361691B (de)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2620033A1 (de) * 1975-05-06 1976-11-25 St Annes Board Mill Co Ltd Stoffauflauf
WO1986004369A1 (en) * 1985-01-24 1986-07-31 A. Ahlström Corporation Method and apparatus for dividing and uniting the flows of high-consistency fibre suspensions
US4952314A (en) * 1987-11-11 1990-08-28 A. Ahlstrom Corporation Apparatus for treating pulp

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4024016A (en) * 1975-12-18 1977-05-17 J. H. Horne & Sons, Inc. Cylinder mold former with flow box and pressure lid
WO1983000173A1 (en) * 1981-07-02 1983-01-20 Eynon, David, Leslie Flow box

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2589639A (en) * 1947-10-17 1952-03-18 Black Clawson Co Paper machinery
US2894581A (en) * 1957-03-26 1959-07-14 Rice Barton Corp Fluid stock distributor
US3016089A (en) * 1958-12-18 1962-01-09 David R Webster Cylindrical pressure headbox
US3328236A (en) * 1964-06-22 1967-06-27 Black Clawson Co Bunched tube approach to a headbox of a papermaking machine
US3565758A (en) * 1966-09-01 1971-02-23 St Annes Board Mill Co Ltd Flowbox

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2589639A (en) * 1947-10-17 1952-03-18 Black Clawson Co Paper machinery
US2894581A (en) * 1957-03-26 1959-07-14 Rice Barton Corp Fluid stock distributor
US3016089A (en) * 1958-12-18 1962-01-09 David R Webster Cylindrical pressure headbox
US3328236A (en) * 1964-06-22 1967-06-27 Black Clawson Co Bunched tube approach to a headbox of a papermaking machine
US3565758A (en) * 1966-09-01 1971-02-23 St Annes Board Mill Co Ltd Flowbox

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2620033A1 (de) * 1975-05-06 1976-11-25 St Annes Board Mill Co Ltd Stoffauflauf
US4083750A (en) * 1975-05-06 1978-04-11 St. Anne's Board Mill Company Limited Flowbox with convergent wall portions
WO1986004369A1 (en) * 1985-01-24 1986-07-31 A. Ahlström Corporation Method and apparatus for dividing and uniting the flows of high-consistency fibre suspensions
JPS62500112A (ja) * 1985-01-24 1987-01-16 エ−．ア−ルストロム　コ−ポレ−シヨン 高稠度繊維懸濁液の流れを分割及び結合する為の方法及び装置
US4964950A (en) * 1985-01-24 1990-10-23 A. Ahlstrom Corporation Method and apparatus for dividing and uniting the flows of high-consistency fibre suspensions
JPH0423039B2 (de) * 1985-01-24 1992-04-21 Ahlstroem Oy
US4952314A (en) * 1987-11-11 1990-08-28 A. Ahlstrom Corporation Apparatus for treating pulp

Also Published As

Publication number Publication date
DE1930795B2 (de) 1973-05-03
PL83181B3 (de) 1975-12-31
GB1228385A (de) 1971-04-15
FR2012275A6 (de) 1970-03-20
DE1930795A1 (de) 1971-01-14
SE361691B (de) 1973-11-12
DE1930795C3 (de) 1973-11-22

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