US2902090A

US2902090A - Apparatus for defibrating hard wood

Info

Publication number: US2902090A
Application number: US600044A
Authority: US
Inventors: Jean E Arguillere
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-07-25
Filing date: 1956-07-25
Publication date: 1959-09-01
Anticipated expiration: 1976-09-01

Description

Sept. 1, 1959 J, E. ARGUILLERE 2,902,090

APPARATUS Foa DEFIBRATING HARD woon Filed .my 25, 195e 4 sheets-sheet 1 SePt- 1, 1959 .J. E. ARGUILLERE 2,902,090

' APPARATUS RoR DEFIBRATING HARD woon Fiied July 25, 195e 4 sheets-sheet 2 FIG 2 Sept. l, 1959 '.1. E. .LARGUILLEFAEv 2,902,090

APPARATUS FOR DEFIBRATING HARD woon Filed July 25, 1956 4 Sheets-Sheet 5 FIG.3G

SePfL1959 J. E. ARGUILLERE 2,902,090

APPARATUS FoR DEFIBRATING HARD woon 0 Filed .my z5, 1956 4 Sheets-Sheet 4 United States Patent C) APPARATUS FOR DEFIBRATING HARD WOOD Jean E. Arguillere, Saint Etienne De Rouvray, France Application July 25, 1956, Serial No. 600,044

4 Claims. (Cl. 162-236) The present invention relates to an apparatus for debrating cuttings of hard wood chips which are oated in a liquid medium by mechanical and eventually chemical means under selected conditions of pressure and temperature.

However, in the paper-making industry, it is usual to give the name of chips to Wood cuttings having a thickness of the order of several millimeters. In contradistinction, in the process of the invention, laminar cuttings are used which have a thickness of between one tenth and five tenths of a millimeter.

It is known that the standard debrating is effected by grating, in the presence of water, wood presented as bars to the outer surface of a cylindrical defibrating Wheel which is driven rotatively, the bars being placed parallel to the axis of the debrating wheel, and by regulating the pressure of the bars on the defibrating wheel, the grain of the delibrating wheel, and the temperature, which is itself a function of the foregoing factors, as well as the temperature and the quantity of the added water.

-On the other hand, it has been proposed to carry out the defibrating of textile materials in an aqueous medium in beaters with oscillating hammer or similar percussion members, which rotate inside a grinding chamber, the inside of the wall of which is provided with a coating of abrasive material. In these hammer beaters, the defibrating is effected by the shock action of the hammers and by the action of projection of ythe textile material against the wall of the grinding chamber, these actions effecting a disintegration of the structure of the textile material, and it is the plasticizing action of the water which protects the individual fibers from the destruction which is unavoidable in a dry medium.

'Ihe apparatus of the invention consists essentially off an annular grinding wheel which has secured to its internal cylindrical surface abrasive particles for abrading wood chips and vanes for driving the fibers cut and defbrated from the chips by said grinding wheel-without percussive effect, said vanes being hollow and formed with perforations in order to supply water and, if required, the liquid chemical products for the desired chemical action to which the chips are to be subjected and for diluting the fibers at a screening station.

The fibrous material to be defibrated is driven in re,-

lation to the annular grinding wheel at the same time as` the required quantity of water, to which chemical products may or may not have been added, by a `device comprising vanes which are rotatable about the axis of the grinding wheel, and it is ground by the action of this circular movement with which itis driven and of the centrifugal force thus produced, by utilizing, at the same time, the speed, the pressure and the increase of temperature due to the friction and or produced artificially, regard being had to the addition of water, to which chemical products may be added if required. As in the standard defibrators, the apparatus combines a fiber-refining action with the grinding action proper.

The device renders it possible to work continuously by feeding the apparatus continuously with fibrous material, with water and, if required, with the desired chemical products, and also by removing continuously' the fibers in suspension.

It is known that disintegration of hard wood chips produces fibers which are shorter than the fibers produced by disintegration of resinous wood chips. In order for the hard wood fibers not to be unduly shortened, the fibers must be expelled from the delibrator as soon as they have been reduced to a given desired' length. Consequently the apparatus is provided with screening means and expelling means which permit the removal of the fibers or bundles of fibers in suspension as soon as their dimensions are less than the given dimenisons.

It may be pointed out that the principle proposed re- Vmains the same if it is the grinding wheel which rotates,

driving the cuttings and the water in its movement of rotation, the difference of speed between the cuttings and the surface of the grinding wheel being produced by a system such as stationary vanes.

It is possible to combine the two devices, it being possible for the vanes to rotate in the direction opposite to that of the grinding wheel.

lOne of the important points to be specified is that the process renders it possible to combine the friction which gives rise to the grinding with conditions of pressure and of temperature which render possible a particular action on the fibrous material which it is desired to work and to do this in the actual grinding zone.

It has been observed that the turbulence created by the vanes in the centrifugal grinder of the invention resulted in emulsifying the air with the liquid, the cuttings and the fibers. and that a certain quantity of air was re moved at the same time as the good fibers; this produced a reduction of pressure inside the grinder.

The. grinder of' the invention possessesy an airtight chamber for deaerating the cuttings, (or the fragmentary fibrous vegetable matter) into, which the cuttings are introduced by airtight means. A cooking liquor of delignifying prod-v ucts is also introduced into this chamber in an airtight manner, and the previous deaeration facilitates the im pregnation of the cuttings by the cooking liquor containing the said products and the delfignificaton of the said' cuttings.

Moreover, inside the grinding wheel, the chemical cooking liquor acts on the materials to be debrated at the: desired temperature and pressure in order to obtain an action on the ligneous incrustations of the said materials, with this important observation that the pressure and the temperature are not connected with each other, since the. pressurel is produced essentially by the centrifugal force; and not by the temperature, as is generally the case when closed treatment chambers are used.V

`In order for the fibers not to be unduly shortened and. to b e expelled as soon as they have been reduced to ai given length it is necessary to work with a relatively high concentration` ofl fibers (concentration as weight of the: bersv contained in the liquid phase) in the grinding zone: in the vicinity of'the grinding-wheel, in order to facilitate: the chemcal and mechanical grinding action, andi with: a lower concentration in the extraction zone of the fibers: in the vicinity of the screen. For example, there willi be: a concentration of 3 to 5% of fibers in the grinding zone: and a concentration of l to 2% in the screening zone- The invention will now be described in detail with ref erence to the accompanying drawings, of which Fig. 1 represents a centrifugal defibrating apparatus according to the invention;

Fig. 2 representsy diagrammatically the different cycles of the apparatus;

Figs. 3a and 3b represent in detail and in cross-section the centrifugal defibrator of Fig. l'. n

Figs; 4 and-5 represent modications of the debrator andof the diluting means, the-pre-impregnating means remaining those of Figs. 3a and 3b.

Referring to Fig. 1, 2 denotes an annular cylindrical grinding wheel clampedbetween twoV cheeks 31and4=off 5 thick plate. iron by'bolts 7, the xingV being eiectedfby' woodenipackingS-z A. rotatable-feed t screw 332 whichrotates inside a worm frame conveys the solid andV liquid= products and opens in the vicinity-of the centre of the cheek. 3. at a point where the pressure due to the centrifugal force is substantially Zero. Inside the cylindrical spaceof.: theannular grinding-wheel; vanes 9; which-areV carried by radial arms itl-and 1%@ and driven by a driving shaft lsupported by. bearings 12 and 13;- can rotate. Belt pulleys. 14v are mountedon theshaft 11. The belt'- 15 28is driven by the motor 8;

Referring to Eigs. 3a and3b theshaftl-lV for driving the vanes is a hollow shaft, the internal hollow. part of whichis separated into twoparts 36.and 37fby a partition 3S,- Thevanes. 9.areflat and hollow blades. which 20 arey parallel to the shaft 11 and voccupynearly the whole ofthe axial lengthof the grinding wheel. Each vaneis carried, in relation to` this shaft, by two radiallarms. 10. rand 10', one of which, 10, which is iXed on the part 3&1 of-the shaft 11, is also hollow. and in-.communication with the inside part 36of the shaft and theinsidezpafrtl of the vane which it carries.

The .shaft 11 also.carries a screening drum 42, the cylindrical surface ofwhich passes in the vicinity ofthe. internal longitudinal:edges.of thevanes .9; The pafrt'z37i' 30 offthe shaft'll, whiclris situated inside the drum, ist perforated with holeslS andthe internalzlongitudinal'. edge of the vanes is also perforated with holeslfwhich, havea-,tangential direction,- i.e. throughwhich the liquid` issues in an orthoradial direction.

The operation of the. debrator is as follows:

Thelaminar cuttings are deaerated in an airtight -,chan1.A ber 47.and are` then introduced into the. centrifugalderiibrator where they are .ground in the grindingzonethat issituated against the grindingwheel2fwhere,thebers 40 haveacertain concentration. y This concentration is new.. duced inthe vicinity. of the inlet into thescreening. drum; 42 by the arrival .of.water through the hollow shaftgr. thehollow arms 165,! thehollowyanes .9 andthe holes 16:;v Thefdischarge. `of` the good .fibers through the holes ofthe. drum 42'; is thus facilitated 1by the dilution.fwhich rendersv 45 possible ,a separationofethe,k bers that.facilitates;.tlieir:4 passage through the holes of the screening drum by pre: venting them frombecoming stopped up.` Thedischarge offthe fibers is ,thus eectedthrough -the drum42 and@A through the pipe 37, which is provided with a regulating; valve 17^-and a connection fora manometer. 13;', The iibersl are :thus Alerl into ya screen19 :(Fig 2) which sorts the coarse pulpf on one side and the nepulp; onthe other side. The coarse pulpis recycled'through the pipe` 2 6-into the airtight chamber 47 and the nepulp is sent through the pipe 27 into a.conditioni ng,orthickeningg lter 20, according tothe process employed;` Thegfilter separates.; good thickened pulp which; is 4available-inthe- 4 piping 2l from the clear waterv orifrom Athe cookingv lquonto be-recycled which rissent through the piping 22, G0 into la tank ,24. If vchemical products are employed the cooking liquor to be recycledisl completed Vby an.addi, tion of .Concentrated cooking liquor Whicharrives throughtthe Vpiping 23and it isvsentbackinto thechamber `47 through the

Vpiping

2,5 and the va1ve34a.

Iny Fig.4, theintroducinggscrew isstill denoted'bY-SS., thegrindingwheel is represented at 2, thelateralcheeks.r of the Aapparatus are yrepresented.at 3 fand, 4,4 the vanes are represented at 4tlar 1d their driving ,shaft isrepref, sented atwll. l'1c ,vanes,areV securedvtothe shaft -by 70 arms 10 a-nd iti. The shaft il, thea'rrnltlandthevanes.. maare hnllovnasfn ,the'.CaS.0fvFig .1 The giding wheel does not occupy the whole of the axialy lengthgof th e..gr.i.nderat1d;.nfthe ,extension ,Of. ,the latter, is Situated a screening drum 48 whichileadsi toanputletpipingL37. '(5

4; The ends of the vanes which are close to the drum are perforated with* tangentialy holesV 41 and the supply` of water, which takes place through these holes, enables the fibers to be diluted at the screening position.

In this modification, as the screen is further from the shaft of the centrifugal grinder than in the case of Fig. 3a, the internal reduction of pressure is greater and the laminar cuttings are better deaerated.

The,modification,showninEig. 5 isyery much like the grinder shown in Fig. 3a. The only'diierenceis that the screening drumv 49 is stationary;A and that: the shaft 44 is overhanging.A The outlet piping S0 is stationary insteadofl beingsconstituted by a'hollow-shaft.

It is pointed out thattherel may..usefully, be considered a selection of the bers by displacement of the screening zone in the radial direction. It is consequently advisable for the screening drums 42, 48 and 49 to be fitted removably in the centrifugal grinders so as to be replaceable byeothercentrifugal screening drums with vaediierent diiametervand; ifrequired, having---perforaticfrnsoffdiffrent' sizes;

Pour examples of application ofthe processof-ftheinvention will now be given, the first relating to-almewVv chanical grinding'andthee other three relating Ito -grinding with chemicallaction.y These -eXamP1S-aPP1Y'eSPe" cially to -the grinding -of hardwood4 for' the' m-anufztetiliferL ofpapen-making'fibers;`

Example 1 i The-wggindingiwheel `has a grainthat is similartothaL of..grjindingwheels ofgrinders for. mechanical paper stock...

Chipsof poplarfwood and .waterare. introducedinto the-app aratus with. ,a..sp,eed of .rotation of the vanes such. that .it creates a. pressureoftheorder of .2.kgs.- per sq.,cm. tog. the,4 manometer 1S. the apparatus operating. continu ously.`

The apparatus. .is provided, with adrurn 42.anda hollow shaft 3,7 comprising holes44 andlS` havingna diameter of.. 1.4. mm., which iilters` the discharge of ,theibers in.` suspensioninwater.

The quantity of water and. of cuttingsisregulated so as to obtainaconcentration of the fibers :of the orderv of 4%`- againstgthe grinding wheel and the rate'Y ofthe water owinggfrom the holes ,16. is regulated 1in.,order1tha.t .thiss concentration should be reduced to 2%v infront'of the grating?.

The magnitude. ofthe. rate ofdischarge.. and, of theerate., of:recycling,1onthe one hand, andthe supplyof cuttings. andof ,-water, which is more or less hot,.on theother, are. regulated simultaneously for the purpose -of maintainingr, in the apparatus, a temperature of the 4order of.50.to.70?v C.

Fibers of poplar are thus obtained which are perfectly. utilisable -in.papermaking, particularly from: the .point of view of draininggbreaking length'and breakand-bleachfV 55 ing .value ExamplelZ Cuttings .of hardwood and a solution ofNaOI-Lare introducedinto lthe airtight chamber in suchiproportionsrv that the ratio of cookingliquor to wood is 4:1 and the" ratio NaOH ,to .wood is 10%. The stirrer 9'-10-'10" whichldrives the cuttingsagainst the grindingwheelwith a pressurethat is developed'by the centrifugaliforce; is rotated. The temperature rises progressively` up:4 to `a temperature of between 50 and 100 C.' at the Ysame timey asthe centrifugal force creates thepressure in the grind-A ingzone, this pressure favouring-the penetration'andthe:V action of the delignifyingliquid. This pressure may-varyy btweenlandd kgs. per sq. cm.V

The Yyield of bers is of the order of `to 90%'l Theonsumption of caustic soda is of then order ofi about 6% in relation tothe Weight of the fibers.V

The cookingliquor is recycled continuously, anditsconcentration is readjusted as indicated 'in relation to' Fig. 2.,l

Example 3 The solution of soda is replaced by an hydrotropic solution, for example an -aqueous solution containing 33.3% of sodium xylenesulphonate.

The yield is ofthe order of 80 t0 90%.

The hydrotropic solution is recycled continuously and its concentration is readjusted.

The lignin is precipitated from the solution when it has become saturated, and the hydrotropic solution is thus recovered.

Example 4 The solution is composed of neutral sodium sulphite and sodium carbonate in such quantities that the ratio NaZSOg/wood is and the ratio NazCOg/wood is 5%.

The yield is of the order of 80 to 90%.

The solution is recycled continuously and its concentration is readjusted.

The apparatus of the invention has been described in vaccordance with particular examples of embodiment. It is to be understood that modifications, which can easily be conceived by a person skilled in the art, are possible and are within the invention. It is particularly pointed out that the grinding wheel may have its axis vertical, that it could consist of removable elements that are liable to become worn out and have a suitable size of grain and are iixed on a stand, and that the filter may be placed in any position in the pressure zone. Finally, the delignifying action may be combined with a chemical bleaching action.

What I claim is:

1. Apparatus for debrating wood chips to produce fibers suited for the production of paper, comprising a centrifugal debrator, means for introducing into said debrator a mixture of wood chips and a liquid medium while excluding simultaneous introduction of extraneous air, said centrifugal deflbrator comprising a cylindrical chamber having abrasive particles secured to the internal cylindrical surface thereof, rotatable vanes for driving the wood chips and liquid medium outwardly against said abrasive particles, said vanes being hollow and formed with perforations, a screen constituted by a rotatable perforated drum secured to said vanes and positioned within said cylindrical chamber, means to move said vanes through a circular path adjacent the interior of said cylindrical chamber, means to remove liquid medium from said cylindrical chamber through said screen, means for supplying fresh liquid medium through said perforations of said hollow vanes to the immediate vicinity of said screen whereby the iibers produced by the abrasive action of said abrasive particles upon said wood chips are diluted in the vicinity of said screen and those bers which have been reduced to a given predetermined length will be selectively removed from said cylindrical chamber through said screen.

2. Apparatus as recited in claim l in which said perforated drum is stationary and located in extension of the axial length of the annular grinding wheel, leading to a peripheral stationary outlet piping.

3. Apparatus as recited in claim 1 in which said perforated drum is stationary and secured to one side of the grinding wheel, leading to a stationary outlet piping.

4. Apparatus for detibrating wood chips to produce fibers suited for the production of paper, comprising an airtight chamber, means for introducing into said chamber a mixture of chips and a liquid medium without the simultaneous introduction of extraneous air, a centrifugal debrator airtight, conveying means between said chamber and said centrifugal deiibrator, said centrifugal defibrator comprising a cylindrical chamber having abrasive particles secured to the internal cylindrical surface thereof, vane means for driving the chips and liquid medium outwardly against said abrasive particles, said vanes being hollow and formed with perforations, a screen constituted by a rotatable perforated drum secured to said vanes and positioned within said cylindrical chamber, means to move said vane means through a circular path adjacent the interior of said cylindrical chamber, means to remove liquid medium from said cylindrical chamber through said screen, means for supplying fresh liquid medium through said perforations of said hollow vanes to the immediate vicinity of said screen whereby the fibers produced by the abrasive action of said abrasive particles upon said wood chips are diluted in the vicinity of said screen and those iibers which have been reduced to a given predetermined length will be selectively removed from said cylindrical chamber through said screen.

References Cited in the le of this patent UNITED STATES PATENTS 1,058,641 Strieth Apr. 8, 1913 1,389,281 Winestock Aug. 30, 1921 1,982,130 Wollenberg Nov. 27, 1934 2,414,361 Cowles Jan. 14, 1947 2,591,141 Dulait Apr. 1, 1952 2,616,802 Kehoe et al Nov. 4, 1952 2,718,178 Wandel Sept. 20, 1955