US2881675A - Method and apparatus for de-watering aqueous pulp or stock in the manufacture or paper or board - Google Patents

Description

R. J. THOMAS METHOD AND APPARATUS FOR DE-WATERING AQUEOUS April 14, 1959 PULP OR STOCK IN THE! MANUFACTURE OF PAPER OR BOARD 3 Sheets-Sheet 1 Filed March 10, 1955 Apnl 14, .1959 R. J. THOMAS 2,881,675

METHOD AND APPARATUS FOR DE-WATERING AQUEOUS PULP OB STOCK IN THE MANUFACTURE OF PAPER OR BOARD Filed March 10, 1955 :5 Sheets-Sheet 2 R. J. THOMAS 2,881,675 PARATUS FOR DE-WATERING AQUEOUS PULP OR ST Aprll 14, 1959 A METHOD AND AP C IN THE MANUFACTURE OF PER OR BOARD 3 Sheets-Sheet 3 Filed March 10, 1955 United States Patent METHOD AND AP;PA RAZEUS FOR DE-WATERING ,AQUEQUS R L'P 40R STZOCKVIN THE MANUFAC- IURE ,OF PARER you BOARD Reginald James Thomas, Weston-Super-Mare, England, assignor to St. Annes Board Mill Company Limited, Bri'stol, England, a British corporation 'ilihis invention relates gto method and apparatus fpr idevwatering pulp or stock fed as ;an open topped layer to the itrave'ling ,carnier band ,of .a :paper or board niaking n a- :Gh'ine. More specifically, his-tinyention dea'ls witna top W q pp drini r typ p pe o t oar zmelin :machine which dc-waters stock upwardly and ,Wherein Sl1Ch upward :dewatering i f cilit t y et o to toommodate slow-speed operation.

:In :the Regin ld .zlames 'Ihemasan a l y d Sm t application :Serial No. 3733382,, {filed ,August 1-0, 195-3, now Ratent2N0.2382i,;120;g nted.Ja a Y,2 5 t e e .is :descrihed and .icla med method ,and ,apparatus :Q1' ;d ewatering pulp Y whereinxstockis Jintroduced between spacedopposednverlying ,:and underlying :forming surfaces comprising an overlyin g Wire and an; underlying carrier hand, a d watfirtfiiom :IhisyStOCki di eha t dupwa dly t r u sthe overlying Wire underthe influence ofkineticenergy dmparted iiOithC stock and ,water byadvancingnaidt l rdiaces. The etraveling :surfaces build up a -sufii cient n oimentum in the water that, as :they ,are squeezed :together in m ingsundae/do tor, he :Wa r will :be t-fl ngith t ll h 1the;t0p5wiresand;flo,w. over the, doctor-, to a drainoutlet.

The present invention no PrQYides method ,and appaira which will ide-zwa'ter :stoek hroug e top x ernfin vwire :10 form ;a I web thereon even when the water is not refinanced la: ,a sufficien ly fast ra e: bu d up a :moimentum; capable, of creating; its own separating forge.

Thus, in accorda-me ,With rthe present iinyention,-;the {top forming wire ,passes llDdQl'gSllCLlOIl meanswhich willpull zthe .water through the wire .10 ;de-wa t er the stock. The :suction means is ,located along a sloping run of -th e ;tqp :wire which, converges-to :apresspre gap.

aThis {invention :i i pplieabl z oei h in l o rml tiple :P y m h ne an th exp ess e flea-Watering i al ie gh reinrme n sth rini al d -wat rin whkh. i ..Ee d :in .e s'type machines, is usually carried outby natural drainage tend by, suction boxes ,a-rranged beneath the traveling earrier band that reduces the:'-,Wa r contentof the pulp to, for ex mpl about 96% toi r thes e into ia ubst n- -tiallycontinuous web.

Uniform .pulp or stock as delivered to vthe traveling forrningiband ofa paper orboardmaking machine usually iconsists of from /2 tol /2% of cellulose vegetable fiber, with or Without other materials, and about 99 [2% v1.0 98 /2 .water, In thisconditipn the stock isfluid so that inflows, freelyonto and acrossithe vforming.band. .In the ,P cess. of manufac u n ,p pe o 'boe the t e i initially ,deewatered toa solid c ontent of, for example, aboutt4%. ,At aboutthisconcentratiqn the fibersinterfilocktandi assum wetru tu za t le ienship h tth rea'fie remains substantially unaltered. The pulpis then s aidto "be formed. Further water is removed fromthe stock,.for example .bysuction hoxes couch rplls, and .wetpresses,

audit ,is finally dried by drying cylinders. Of course, it is highly desirable to enioye as wmuch water as possi e im e mem Wh do ne i m i exces i u we The e ql'e he .prt y sie of th ov r y o t p forming wi e a t th t -Wat r n v f t e s k up a y r m th layer of {pulp on the b ottom forming band when this layer i in it flu dsta e, e e 9 e s e of q e et smq he m chine re r en s an .im q i m edivnet o e 1 f?- ention of t e af esai a plicati n Se a J 37 381 Th p esen n ent a t the P incip es vo h atti se s anpl ee qn to lqwau mln ma hine 7 it ;is then ,asuhjeet of this invention to provide for the "upward s -rvet rin e etqek t h an qve l ing fQI "m w re p a e 9 b d me n meeh n re dle of the speed of operation vof the n a chi ne. I I

. a ,A fu he QbieQ .q thi in ention i to .p i yi e ,e ep o 4 .e :mek mehin hey e ta -farmin w reend tsuet n ean a t n thrpu 'hee d W e t s uete tae in an upward direction.

.Anethe ab e t o thi n entie i 19 ade t e P nleeq ep l eetien 5er e 1N9- 38 to endo unn n Ma hine- Another object of the inyention is to providea suction hexaseemb ypn a ene te bee rmek 'n m et! eWh be t t yasii d to uidee top em nist. (i e- Astin ,iiurth n Jes i thi inve ien i810 ,P iQYiQe 1 Board ".e type epe or a drmek n eeh ehev n a 19 s ming W r wit s d tleekl which wil ,eeq era t me teih d 9 wekvi fm o a d he wed .sha edtt rm a are ibe wee the m ntreve n en an t h vtq tfmmi iw e i Other and further objects of this inventiqn will beapparen t the e skille i th r om t e .fqllo in -v it leil ser pti n. e th ann xed shee s. o drawin wh ch by w y preferred ex m le lus r t etete iembad ,ment of flienr nt e 9 the drawing i ut yi el'eemewhe iagr ati i el ation? ,vie 'p Peaew -.bQ.eI -Jmekin m c n iea e mrsiina oth invea pt giir 5 1 a Y ew s mil a to F ur .i l st etin portion of the wet end of the machine to shpwjthe in Wh FhJh l WflI JB .Qflth to ireieediust to ram e slop lhe eefv ;Fi. ur. 13li .e-transve as e iena riewiakenelsm ith 5 .nev I' .II .Q Fi ur .F gur ,1 a s mewha siieg e m ie i. l ..e ve 9ae tviewef pepeno beers zmek n mee' i ewetend e u pped with a plurality o'ftop wires according to 'this inyem .tiou.

,Th we end 0 Qfth top I Wi -e ppe liou d ip e .type paper or hoard-making machine shownin Figure ,1 includes a base frame 11,and an overheadfi'ame 1 2.

(A. nain f orrning ,wire :13 is looped arounda breast roll ,lg l a epuchroll 15, over, a plurality ofi ta'blerolls 16,,, and under, guidetrolls such as .17 .so as-;.to. have .an velongated substantiallyhorizontal. upper run between the couch and xbre st o l A topformingpwire ls is trained arqund an adjustable ,onco ning roll 19, an olfgoing roll 20, ,and L guide -,1folls su-ch ;.as,21, supportedfro m the framelz.

Tension rolls 22 and J3 respectively, cooperate with the-sn d r ll 1 sen 2 ihol in th W e e .1 mi h -912? le p r911 1.9..end lfi' e th we W r -I18 t z pw q a hottom run over the top run of thewire-l}. suction box assembly 24 is mounted over this bottom run of the top wire 18 immediately downstream from the adjustable oncoming roll 19. This assembly 24 has its rear downstream end hinged or pivoted at 25 to a pair of depending columns such as 26 carried by the overhead frame 12. The pivot 25 can be raised or lowered by means of an adjusting screw 27. V

A plurality of suction boxes such as 28, 29, 30 and 31, are provided in the assembly 24 and each box has a perforated or slotted bottom receiving the under-run of the top forming wire thereover. Drain conduits 32 are provided for each suction box. These conduits discharge into a header conduit 33 which is connected to a suction pump for evacuating the suction boxes. A valve 34 in each drain conduit 32 controls the degree of vacuum in each suction box and the valves can be regulated to provide, for example, a progressively increasing degree of vacuum in successive boxes. The front end of the assembly 24 is suspended from the top frame 12 by adjustable supports such as 35. For purposes of illustration, 3. turnbuckle support 35 is indicated to raise and lower the front end of the assembly 24 thereby swinging the assembly about its hinge or pivot 25.

Screw rod adjustments 36 are provided on the supporting columns 37 for the oncoming roll 19 so that this roll can be raised and lowered with and in front of the box assembly 24.

A relatively large diameter support roll 38 is mounted in the loop of the wire 13 under the upper run thereof to have contact with this upper run at the oncoming end of the suction box assembly 24.

A plurality of press roll assemblies 39 are provided downstream from the suction box assembly 24 and each assembly 39 includes a bottom roll 40 in the loop of the wire 13 and a top roll 41 in the loop of the wire 18. The rolls 40 and 41 cooperate to form a horizontal pressure nip squeezing the wires toward each other. If desired, the presses 39 can be suction presses with suction boxes in either the roll 40 or 41 or in both of the rolls as desired.

The oncoming roll 19 and the suction box assembly 24 are adjusted so that the bottom run of the wire 18 will cooperate with the top run of the Wire 13 for forming a wedge gap 42 which diminishes in height to the pivot 25. Thus, the gap has an entrance mouth determined by the roll 38 and a convergent run from the oncoming roll 19 to the pivot 25 determined by the box assembly 24. The rear end of the suction box assembly serves as a pressure line at the terminal end of the converging wedge gap 42.

A stock inlet or head box 43 is mounted adjacent the breast roll 14 to supply stock to the open-topped upper run of the main forming wire 13. Stock is supplied to the head box through a conduit 44 and is fed from the head box under any suitable slice arrangement onto the wire between deckle boards 45 arranged above the edges of the wire.

The deckle boards 45 do not extend right down to the edges of the wire as this would cause too much wear. Accordingly air deckles 46 are secured inside the boards 45. These air deckles are perforated or slit along their bottom edges so that they act, when connected to an air supply, to direct a curtain of air along the edges of the wire to confine the stock on the surface of said wire. Since the free flow of stock is restricted under the oncoming roller 19, it forms into a pond 50 extending from in front of the oncoming roll 19, where it builds up as a wave 51, into the gap 42 as far as the pivot 25.

If desired air may be directed as a curtain to provide air deckles at the sides of the gap 42 right up to the pivot 25, but these are not indicated in the drawings.

- As the wires are advanced in the direction indicated by the arrows, the stock advances into the diminishing gap 42 and water drains through the bottom wire and is drawn upwardly through the top wire into the suction boxes. If desired, the roller 38 can be equipped with a suction box so as to increase drainage downwardly through the wire 13. The table rollers 16 and the bottom faces of the suction boxes 28 to 31 hold the respective runs of the wires rigidly so that the forming gap will withstand the load of the stock therein. Since drainage occurs both upwardly and downwardly, the stock forms simultaneously on both wires and improved fiber formation is thereby obtained. After the stock passes under the hinge or pivot 25, the presses 39 squeeze the pulp that is formed on the wires to remove further amounts of water therefrom. The squeezed out water on the top of the wire 18 adjacent each press 39 can be removed with suction slices 48 which may be provided on the downstream side of each press 39.

The gap 42 can be changed in accordance with pulp conditions. This is accomplished by merely raising or lowering the oncoming roll 19 and by similarly adjusting the turnbuckle 35 to raise or lower the forward end of the suction box assembly 24.

As illustrated in Figure 4, the multi-ply machine 10' has most of the parts identical with parts described in connection with Figures 1 and 2, and the same reference numerals have been used to identify these identical parts. In the machine 10, however, the bottom wire 13 is equipped with two top wires 18 each having a tiltable suction box assembly 24, and with a feed box or inlet 43 in front of each top wire to supply stock into each wedge gap 42. The first inlet deposits the stock as an open topped layer onto the bare upper run of the wire 13 while the second inlet deposits stock onto the previously formed web on the wire 13. Each top wire 18 dewaters the stock under the influence of suction from the suction box assembly 24 mounted in the loop thereof.

From the above descriptions it will, therefore, be understood that this invention provides a paper or boardmaking machine and process wherein the layer of pulp from a stock inlet is flowed onto a main forming wire and is carried thereby under a converging top wire having a wedge-shaped forming gap relationship with the main wire that decreases in height so as to provide a restriction which will maintain a pond of stock between the wires. Suction mechanism is provided to act through the top wire for de-watering the stock from the pond in an upward direction and while kinetic energy is imparted to the water in the stock pond by the advancing forming wires will assist the de-watering, the machine can be run sufliciently slow so that this kinetic energy is practically negligible because the suction mechanism will draw the water through the top wire. After the stock passes beyond the' convergent end of the gap between the sloping portion of the top wire and the bottom wire, i.e. the pivot 25, it is sufficiently formed so that it will not flow off the wires and it can be pressed between the wires for further water removal. The machines of this invention may be used in tandem or several top wire assemblies can be provided on a single bottom wire machine whereupon a web of any desired number of plies or layers can be produced. It should be understood, however, that the resulting web will have the fibers so interlaced that the plies are inseparable. Further, since de-watering takes place through the top wire or wires, the stock for any ply or layer may be so dense as to permit no drainage to take place through it, thus it will be appreciated that pulp combinations of any desired types can be used. Thus, it is possible with the machines and methods of this invention to deposit a very'dense impervious stock on the main wire and to then build up a superimposed layer or layers of any desired nature on this dense layer. The stock is pressed sufficiently between the forming wires so as to form a self-sustaining web before the support of the main wire is removed.

The suction acting through the top wire or wires can be regulated as desired so as, for example, to have a advancing 'opposed top and bottom foraminous "forming wires along converging paths providing a tapering gap with an enlarged entrance mouth, introducing into said mouth bet-ween the opposed forming wires thin -watery fibrous =we'b forming stock of sufficient fluidity to fiow freely onto and across the wires,-ma'in'taining a turbulent 3P5 pond of said stock between said wires with the fibers in the pond freely dispersed, building up a wave of turbulent stock at said entrance mouth for feeding into said gap, sucking water from said pond through the top wire to interlock fibers and form a web on the underside of the top wire, simultaneously draining water from said pond through the bottom wire to interlock fibers and form a web on the top face of the bottom wire, building up the webs on the wires to interlock the free fibers between the webs on the top and bottom wires as the wires advance toward each other to integrally unite the webs through interlocked fibers, and squeezing the partly de-watered stock and webs between said wires to remove further water therefrom and form a unitary interlocked fiber web from said webs.

2. A method of making a fibrous web which comprises depositing aqueous stock having freely dispersed fibers on an open topped portion of the upper run of a Fourdrinier forming wire, covering the stock before it is formed into a web with the bottom run of a top forming wire so as to leave a gap between the wires with an enlarged converging entrance mouth, progressively diminishing the gap to provide a wedge-shaped forming area between the wires, maintaining a pond of fluid stock with freely dispersed fibers under hydraulic head pressure in said wedge-shaped forming area, advancing the wires in the same direction to advance the stock in said pond through the diminishing gap, restricting the entrance mouth of the gap to build up a wave of stock at said mouth, evacuating the bottom run of the top wire to de-water stock upwardly through the top wire and form one surface of a web on the under face of said top wire, simultaneously draining water downwardly through the upper run of the Fourdrinier wire to form the other surface of the web on the top face of said upper run, building up the web formations on both wires as the wires advance toward the convergent end of said gap, and pressing the wires together at said convergent end of the gap to interlock adjoining fibers of each of the webs into a unitary interlocked continuous fiber sheet having top and bottom wire sides.

3. A web making machine which comprises a main looped forming wire having a substantially horizontal upper run, a top looped forming wire having a bottom run overlying a portion only of the upper run of said main wire, a directing roll within the loop of the top wire guiding the bottom run of the top wire toward the upper run of the main forming wire downstream from the start of said upper run, a suction box assembly in the loop of the top wire downstream from said directing roll, said assembly having a bottom face guiding the bottom run of the top wire and shaping the top of a gap between the top and main forming wires to diminish in height downstream from the directing roll, means for adjusting the suction box assembly and thereby vary the height of said gap, means for adjusting said directing roll and thereby vary the height of the entrance mouth to said gap, deckle means in advance of said directing roll cooperating with the upper run of the main forming Wire and confining the stock thereon, and a stock inlet :ha vi-ng means for depositing a layer of fluid aqueous stock 011 said upper run of the bottom'wire between said deckle means forming a pond in said gap of a depth creating a wave against ,the descending quadrant (of the directing roll whereby drainage through the top and bottom wires forms webs :on both .the wires which .are mnited :as the wires approach the convergent :end of the gap.

4. A web making machine which comprises a :main forming wire having a substantially horizontal upper run, a ilooped top .tforming -wi-re Ihavi-ng .a ibottom run overlying a portion of ,said horizontal upper run and defining the top of a gap "between said runs, a directing roll in the loop of the top wire having a lower quadrant guiding the top wire to the entrance mouth of said gap, means for raising and lowering said tdirecting roll and thereby varying the height of said entrance month, an elongated suction box assembly in the loop of the top wire having a bottom face overlying said bottom run of the top wire and extending from directly adjacent the directing roll a considerable distance downstream therefrom, a first means for adjusting the height of the upstream end of said suction box assembly to thereby control the height of the gap between the wires immediately downstream from the entrance mouth to the gap controlled by said directing roll, second means for adjusting the height of the downstream end of said suction box assembly to thereby control the height of the discharge end of said gap, said first and second adjusting means being relatively adjustable to thereby control the inclination of the suction box assembly for varying the shape of the gap between the entrance mouth and the outlet, and a stock inlet having means depositing aqueous stock on the top run of the main forming wire upstream from said directing roll and for forming a stock pond in said gap with a raised wave against the lower quadrant of the directing roll.

5. The method of making a fibrous web which comprises advancing opposed top and bottom foraminous forming wires along converging paths, controlling the path of the top wire to coact with the bottom wire in forming a tapering gap between the wires with an enlarged arcuately converging entrance mouth, introducing a dilute fibrous web forming stock between the opposed forming wires, maintaining a turbulent pond of stock with freely dispersed fibers in said gap; between said wires, building up a wave of turbulent stock in said entrance mouth removing water from said pond through both of said wires, creating a pressure difierential across at least one of said wires to assist in removal of water from the pond, forming webs on both wires as the wires advance along said converging paths with the adjacent opposed faces of the webs merging through freely dispersed fibers in the pond, and squeezing the webs between the wires to further remove water therefrom and interlock the webs with said fibers at the opposed inner faces of the webs.

6. A web making machine which comprises a looped main forming wire having a substantially horizontal upper run, a looped top covering wire having a bottom run cooperating with the upper run of the main forming wire, an impervious directing roll in the loop of the top wire having a lower quadrant shaping the top wire and forming a converging entrance mouth to a gap between the bottom run of the top wire and the upper run of the main wire, an elongated suction box in the loop of the top wire extending from a point immediately adjacent the directing wire to a point downstream from said directing roll, said suction box having a bottom face receiving the bottom run of the top wire thereagainst and controlling the run of said top wire as it is received from the directing roll, means for varying the position of said suction box and thereby vary the position of said bottom run of the top wire, means for varying the position of said directing roll and thereby vary the entrance mouth to the gap between the wires, and a stock inlet, said stock inlet having means for depositing a layer of watery stock ,on the upper run of the main wire, said stock inlet, said means for varying the position of the suction box and said means for varying the position of the directing roll being relatively adjustable for maintaining a pond of stock in the gap between-the wires with a wave deeper than the pond in said entrance mouth thrusting against the lower. quadrant of the directing roll.

References Cited the file of this patent UNITED STATES PATENTS 8 Lappen May 25, 1915 Babcock June 22, 1915 Shaw July 8, 1924 Hinde Jan. 15, 1929 Upson a- May 19, 1931 Richardson Feb. 11, 1936 Hutchins Dec. 27,1938 Roman May 11, 1948 Reynolds Jan. 17, 1956 Thomas et a1. Ian. 28, 1958 FOREIGN PATENTS Australia May 25, 1906 Australia Apr. 10, 1936 Germany May 12, 1939 Germany Mar. 18, 1943

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