US1790714A

US1790714A - mantius

Info

Publication number: US1790714A
Authority: US
Publication date: 1931-02-03
Anticipated expiration: 1948-02-03

Description

O. MANTIUS METHOD OF WASHING PULP Filed April 6, 1928 3 Sheets-Sheet 1 ATT @Y wm Feb. 3, 1931.

Feb. 3, 1931. o. MANTlus METHOD oF WASHING PULP Filed April 6, 1928 3 Sheets-Sheet 2 QN Il."

` 4Q .lll-III l@ O a lumwiumio A, G Q. w

@Qwglml 1 Feb. 3, 1931. o, MANTlUs 1,790,714 *l METHOD oF WASHING` PULP Filed April e, 1928 s sheets-sheet 3` A ORNEYS.

Patented Feb. 39 il' OTTO MAN'LIUS, 0F NEW YORK, N. Y.

METHOD 0F WASHING PULP Application medi April 6,

This invention is a method of washing pulp and is more particularly directed to the removal of chemicals from pulp produced by the soda, sulphate or sulphite procr, esses well known to the art. i

After pulp is discharge from the digester, it is the practice to remove therefrom the soda,- sulphate or sulphite, which it contains in order to recover such chemical and to prepare the-pulp for bleaching. This washing has been generally carried on heretofore by passing the pulp from the digester to large wash tanks or diusers which, in many' instances are arranged in batteries through which the pulp to be washed is successively fed, while fresh water is passed through the tanks to wash out the chemical.'

This well known washing arrangement requires large amounts of fresh hot water for carrying on the operation 'and is vtlius eX- pensive. Furthermore, when very y large quantities of water are used to wash out'the chemicals, these chemicals form a solution with the water and in order to recover them costly processes of concentration and recovery are required.

The purposeof the present invention is to provide a method vwhereby increased eiiciency may be obtained in the washing of pulp through the use of a novel method of manipulationof .the xmaterial which makes it possible to accomplish the result by the use of'relativelysmall quantities of water, as compared to prior known processes.-

I am able to accomplish this'result by entirely departingy from the wash tank batteries and diifusers of prior practice and in lieu .thereof subjecting the pulp to successive washing operations with intermediate applications of pressure.

In practice, the pulp, as discharged from the digester, usually contains about 90 partsof water to 10 papJts ofpulp, and in this water the chemical, which it is desired to re- 45 move, is contained in solution. The initial 1928. Serial No. 267,977.

step in this method consists in subjecting the`pulp of the water last added together with such additional chemical as may have become admixed therewith. These operations are repeated and before each pressing operation I add tothe pulp additional water to 'further dilute the chemical contained therein, so that when the pressing operations take place, thel water' which lis removed during such operations carries off with it a part of the chemical in solution. Forexample, if the pulp is compressed as it comes from the digester, a large portion of the water content will be removed and the pulp will be partially dehydrated' through such compression. If the pulp is thereupon thoroughly admixed with more water, a further `portion of the chemical `which remains in the pulp will be diluted by the water.

At the conclusion of this washing operation, which consists in thoroughly admixing the. partially dried pulp vwith further water, the pulp is again compressedvt'o again partially dehydrate it by squeezing out the water previously added( This water carries o' with it a further portion of the chemicah If these "operations are repeated several times, an unusually eiiicient removal of the chemical from the pulp results and this eiiciency is materially increasedl if, before each pressing operation, the washing operation is accompanied by a shredding and intimate admixture of the pulp with the diluting water to which I have referred.

Thus. the fpreferred practical manner of carrying out the present invention consists in pressing the pulp to free it of a portion of Vits water-fchemlcal solution, thereafter shredding thepulp and thoroughly admixing itl with further diluting water, and thereafter repeating these steps inthe sequence stated any vdesired number of times found requisite to impart tothe pulp the desired freedom of chemical content. i

Furthermore, in practice, l find it entirely satisfactory and in fact highly desirable to take the washwater resulting from one washing stage and use it in the next preceding washing stage, preferably using fresh water furthe last washing stage. I am thus required to feed fresh water to only the last washing stage and .to' supply water to the preceding washing stages by what may be termed countercurrent washing. By cmploying this type of Washing, the amount of water ultimately used is but a small fraction of that used in prior processes, with resulting manifest advantages among which may be mentioned economy in hotwater and also the economy of steam required for the 'recovery of the chemicals through concentration for further use.

l have found it highly desirable in practice to obtain the most intimate contact between the water and the pulp bres during the washing operation, in order that maximum dilution may result during each washing operation., l therefore preferably subject the .pulp during, and as a part ofthe washing operation,4 lmeading action in the presence of the wash water, so that the pulp is thoroughly washed and maximum dilution results.

`-Further important practical features will be apparent from the following detailed description and claims when read in conjunction with the accompanying drawings.

The accompanying drawings illustrate one practical form of apparatus for carrying out the method of this application, but inasmuch as other forms of apparatus may be used to accomplish this result, the showing made in the drawings is to be upderstood as illustrative, only, and not as defining the limits of thetinvention. "i,

Figure lis a diagrammatic view showing apparatus for carrying out the process of this invention. f

Figure 2 -is an enlarged detail elevation showing `apparatus forming` a part of the structure illustrated in Figure 1, and functioning to press the pulp in order to squeeze the water therefrom.

Figure 3 is a vertical longitudinal. section through shredder and washing appa atus shown diagrammatically in Figure 1; This .section istaken on the line 3 -3 of Figure 4.

Figure 4 is a plan vievwr of the structure rshown in Figure 3.

Figure 5 is a side elevationof the same 'structure showing the manner 1n which the moving parts are driven.

'Figure 6 is a. section showing' apparatus to a shredding and.

r'for removing a portion of the water squeezed out from the material. l

Figurev7 is a section-on the line7-7 of Figure 6 showing certain parts in elevation.

rlhe whole apparatus is preferably, though not essentially, mounted within a. suitable casing designated in Fig. 1 of the drawings by the reference character 1. '.lhis casing may be of any suitable form or construction and may', in practice, be the room of a building.

By reference to Fig. l, it will be noted that there are a number of conveyors mounted within this casing, and in this ligure, l ave operates with the upper reach 12 of the conveyor 5, while the lower reach 13 of the conveyor 5 cooperates with the upper reach 14 ofthe conveyor 6.

llt will be noted, moreover, that the conveyors are positioned in staggered relation, so

that each projects' a distance beyond the other in order that pulp placed on the conveyor 3 to the left of the conveyor 2 in Fig. 1 may be fed by the conveyor 3 between the reaches 7 and 8 to be fed after passing between said conveyors to a shredder and washer 15 'positioned beyond the discharge 'end of the conveyor 3. This shredder and washer is positioned above the projecting portionof the conveyor 4, sothat after thefmaterial is passed through the shredder and washer 15, it is fed to the conveyor 4 to be carried thereby between reaches 9 and 10 of the conveyors 3 and 4 and discharged into a second shredder and washer 16 from' which' it is in turn dislll) charged on to theconveyor 5 to be carried a thereby between the

reaches

11 and 12 of the conveyors 4 and 5 and thereupon discharged into athird shredderand washer 17, fromwhich it is thereafter-discharged on to the lowermost conveyor 6 to be carried thereby `between the reaches 13 and 14 and delivered down an incline 18 through a hole 18 into a suitable trough -by which thematerial is conveyed away.

.All of the conveyors 2-6 are of the same construction. and I nd it highly Kpractical to.- employ slat conveyors, such as shown in Figure 2. Here each conveyor is illustrated as embodying metal slats 20 extending transversely of the direction of travel of the conveyor'and for the full width of the machine. These'slats are positioned edge to edge and are mounted on sprocket chains 21 by which :they are supported and moved. The sprocket lll() f positioned a plurality ot pressure rolls 23,

24 and 25 and cooperating with the upper reach 8 of the conveyor 3 and positioned directly below the

rolls

23, 24 and 25 are con operating rolls 23a, 24a and 25a. These rolls are positioned to engage with the backs of the slats 20 of the conveyors with which they cooperate and, as shown in Fig. 2, said rolls Vare positioned at progressively decreasing distances apart. Thus, the rolls 23 and 23a: are positioned slightly further apart than the rolls 24 and24a which in turn are positioned slightly further apart than the rolls 25 and 25a, so that those portions of the conveyors which travel between said rolls form a conf verging mouth in the direction of travel of the conveyors. The

rolls

23, 24 and 25 and the cooperating rolls 23a, 24a and 25a are mounted in suitable bearings, so as to be held firmly in position although the bearings may be spring pressed or weighted so that if the conveyors meet with abnormal resistance due, e. g., to unyielding foreign matter carried into the converging mouth by the material acted upon, the rollsmay slightly retract orbe moved apart sufficiently to permit the material to pass through without damaging the apparatus. l

Under normal conditions, however, the pressure rolls are mounted so that the `cooperating reaches of the conveyors will not move apart, but will subject the material fed between said conveyors to a constantly increasing pressure as it iscarried along by and with the conveyors. Thus, if material is fed on to the upper reach of the conveyor 3 down a feed table 26 and is carried by the conveyor into cooperative relation with theconveyor 2, it will necessarily follow that such material will be carried through the converging pressure mouth formed 1n the manner described whereby the material will be compressed in a substantially solid cake and during this operation, a large percentage of the water contained in the material will be squeezed out therefrom.

The rollers which l have described are those cooperating with the lower reach of the conveyor 2 and the upper reach ot the conveyor 3, but the three sets of rolls associated with the other cooperating reaches of the several conveyors are formed and mounted in the same manner and function for the same purpose as already explained. ll refer in this Connection to rolls 33, 34 and 35 and their cooperating rolls 33a, 34a, and 35a, as well as the rolls 43, 44, and and their cooperating rolls 43a, 44a, and 45a and also the rolls 53, 54 and 55 and their cooperating rolls 53a 54a and 55a. As a matter of fact, the severa sets of rolls are pressure rolls and their purpose is to provide sucient pressure to squeeze out a large proportion of the material presented thereto and to form the material into a substantially solid cake. Y During the pressing operations, considerable water is freed from the material and' this water is caught by troughs 30, 40, and which are positioned directly beneath the upper reaches oit' each ot the

conveyors

3, 4, 5 and 6,

lhe Shredders and washers of which three are shown in Figure l are illustrated more' in detail in lBligs. 3 to 5 inclusive. All of the washers areot the same construction. Each embodies a suitable tank 6l in which is mounted a plurality ot drums 62, 63 and 64, three of which are shown, although a greater or lesser number may be provided. The -K drums are mounted to rotatelon parallel axes in suitable bearings and theA bottom of the tank is in the form of arcuate shaped troughs 62a, 63ul and 64a. Ilhese troughs are curved on radii of which the axes of the respective drums are thecenters. The periphery of each drum has formed thereon diamond shaped studs and similarly shaped studs are formed on the inner faces of the troughs in such manner that the studs of the respective i parts are substantially complementary to one another, but are so placed as to permit rotation of the drums in the troughs and with respect to one another.

rlhe arrangement may be fully appreciated from the showing in Figs. 3 and 4 and it may be stated that there is one less annular row of studson the trough 62a than on the cooperating drum 62. lhe same relation exists as to the drum 64 and the trough 64a, f

whereas there is one less row of studs on the drum 63 than on the cooperating trough 63a. rlhis produces a staggered relation of the parts whichpermits ot rotation. Because ot' the intertting of the studs, however, the material passed through the 'washer is subjected to a shredding and at the same time a knead ing action, while the rotation of the drums serves to simultaneously feed the material 'fed into the tank 'from the feed table 66 longitudinally through the tank and thoroughly l 63?; and 64b with which a belt 69 is associated. This belt is passed over the several pulleys referred to and around directional and tensioning pulleys 70 and embraces a pulley 71 nounted on the shaft which drives the conveyor 3 so that the several drums are driven from the shaft 72 which drives the conveyor 3, whereby the several drums are driven with the said conveyor.l Y 9 By reference to Fig. 1, it will be noted that the shredder and washer 17 is supplied withv fresh water through a pipe 73. rllhe shredder and washer 16 is supplied from water in the trough 60 through a pipe 711,9 while the shred- 'ler and washer 15 is supplied-by water from the tank 50 through al pipe 75. A pipe 76 delivers water from the-trough to the outlet pipe 84 which leads to suitable recovery appa-ratus.l Suitable pumping means, shown as entrifugal pumps 100, is provided for causing the passageof Water through these pipes.

The apparatus which ll havel thus far described is employed in operating upon pulp in the following manner. rlllie pulp is taken 11s it comes from the digester in avloose semisolid condition and containing generally about 90 partsof water-chemical solution and 10 parts of pulp, and this semi-solid mass is fed into the apparatus down the table 26 y on to the conveyor 3.

The wetsemi-soli'd mass moves along with the conveyor 3 until it is carried thereby into Jcooperation-with the conveyor 2, whereupon both conveyors cooperate to compress the nass and feed it through the tapering mouth between the (pressure rolls 23, 23a, 2a, 24a, 25 and25a. 'During fits passage between said rolls, it is subjected to increasing pressures and a large percentage of the water `therein is squeezed out so that the material will be delivered from the last cooperating rolls 25 and 25a in the form of a relatively solid cake or web. The water which is :treed in the manner described carries lwith it an appreciable part of the chemicals which enter into solution .with the water. vThe water treed 'from the under side oit 'the material passes i through the cracks between the conveyor slats and falls into the 'trough 30. ylFhe water treed from the upper face of the material is squeezed through the' cracks between the slats ot the upper conveyor on to the upper surface of the lower reach of such conveyor. part of this water overiiows through a bypass pipe 7 7 'in o the trough 30, while the rernainder'oiE sucn water is picked uplby the aparatus shown in Figs. f8 and 7 and delivered to the tank 30 through a pipe 7 8.

The vapparatus shown in Figures 6 and 7 embodies a perforated metal cylinder 79 mounted to rotate 'freely on hollow trunnions 80. 'llhe cylinder 7 9 is covered with absorbent materiall, such as sott telt which as 1t rolls overwthe conveyor acts as a blotter to suck up the water.. A hard surface roll 82 maarre bears against the felt covering 81 at the top thereof and causes the water to be squeezed out through perforations in the circumfer- Vwhere a pump would not operate satisfactorily.

Apparatus such as shown in Figures 6 and 7 is associated with each `gang of pressure rolls and an overflow pipe 77 also cooperates therewith. v y

The solid cake or ribbon resulting fromthe first pressing operation is delivered from the conveyor 3 by way of table 66 to the iirst shredder and washer 15. Illhis shredder and washer thoroughly shreds the cake or comminutes it While Washwater is fed to theshredder and washer through a pipe 75.

rllhe shredding and washing thus takes place in the presence of further water in order that the chemical within the material may be further diluted. The material is delivered from the shredder and washer l5 in efliciently divided form and in a wet semi-solid condition to the upper reach of the conveyor 10, which serves to carry the materialv into cooperation with the lower reach of the conveyor 3 and these conveyors collectively pass the material through the second pressing operation to again form the material into a cake and simultaneously squeeze out the watercheniical solution into the trough 40. After leaving the second gang of pressure rolls7 the material is delivered to, a second shredder and washer 16 supplied with water' through the pipe 74 and wherein a second shredding and washing operation with further dilution takes place. 'llhe material is delivered from the second shredder and washer on to the upper reach l2 of the conveyor 5 to be carried thereby between the third gang of pressure rolls, which deliver a third cake or web toa third shredder and washer 17 and simultaneously deliver the products of the further vdilution to the tank 50.

The shredding and washing operations described are repeated in the apparatus 17 supl'lO maarre subsequently compressed, 4this diluent is squeezed out', carrying therewith a portion of the chemical previously contained in the pulp. ln other words, each time the material is washed and thereafter compressed, it is freed of a further portion of the chemical so that by successive washings and pressings, the material is finally freed of substantially all its chemical content. ln practice, l find it thoroughlypractical to feed fresh water through the pipe 7 3 to the last washer 17, while the

washers

16 and 15 are supplied from the troughs 60 and 50, respectively. This constitutes in effect a countercurrent washing with the last washing stage utilizing fresh water.

f This is a highly ecient manner of treating the material since ai relatively small portion of fresh water is required with conse uently less water flo-wing from the trough 30 t rough the pipe 84 for treatment to recover the chemicals.

Particular stress is placed on the fact that the operation of treating the pulp is continuous,the pulp being in the state of continuous movement from the time it enters until it leaves the machine. .'llhus, I am able to obtain with a minimum supply of water a thorough washing with maximum speed and out- The pulp which is operated upon by the apparatus shown and described is of a very slippery nature which renders its compression by rolls alone diihcult. It is for this reason that the continuous cooperating conveyors are employed in conjunction with the rolls to eflicientlyifeed the pulp through the pressure zfones.

vEach roll assembly has been illustrated as embodying three sets of cooperating rolls, but a greater or lesser numbermay be used. Moreover, if desired, l may employ pressure roll assemblies of the Vcharacter described and claimed in my Patent No. 1,764,456 of i June 17, 1930, Fiber board machine but isf - such apparatus is not essential for the carry ing out of the present method, it being particularly desirable here to produce a ushingor circulation of the water through the material so that it will entrain the chemicals and carry them of in solution.

:It will be apparent from the foregoing de# tailed description of the method and one form of apparatus used in performing the same that this method of manipulating the pulp to free it from its chemical content is a marked departure from the prior practicegof employing open wash tanks or diiusers with many times the amountof water utilized in performing the present process. Moreover, by employing mechanical washers and shred ders, a thorough washing 'results and the diluent is brought into most intimate Contact with all the fibres of the pulp, a circumstance which is absent inlpractically all prior practice. ln other words, thepresent invention' provides for the most intimatecommingling order that a maximum dilution may result.

c llt may be further noted that the detrimental channeling so common in open wash tank operation cannot occur in the `method oflthis invention. i

rlhe foregoing` detailed description sets forth the invention in its.. preferred practical form. The apparatus shown as illustrative has been found to give thoroughly satisfactory results, but inasmuch as other and different apparatus may be employed for the same purpose, the method is not restricted to the use of th: t shown in the drawings. @n the contrary, the method of this invention is to be understood as fully commensurate with the appended claims,

Having thus fully described the invention, what l claim as new and desire to secure by Letters Patent is:

1. The herein describedl method which consists in subjecting pulp, in a loose watery con dition and containing a chemical, to pressure to squeeze out an appreciable portion of the water and chemical Icontained therein, thereafter kneading and shredding the pulp in a bath ofl diluent to thoroughly and intimately commingle the fibers of the pulp with the diluent to dissolve the chemical still con-l tained in the pulp, then again subjecting the -pulp to pressure to substantially free it from such diluent whereby further chemical which has entered into solution with the diluent isl removed from the pulp.

2. The herein described method which consists in subjecting pulp, in a loose watery condition and containing a chemical, to presv sure to squeeze out an appreciable portion of the water and chemical contained therein, thereafter kneading the pulpA in ,a bath of diluent to thoroughly and intimately coinmingle the bers of the pulp with the diluent to dissolve the chemical still contained in the pulp, then again subjecting the pulp to pressure to substantially free it from such diluent whereby further chemical which has entered `into solution with the diluent is removed from the pulp.

3. The herein described method which consists in subjecting pulp, in a loose watery condition and containing a chemical, to pressure to squeeze out an appreciable portion of the water and chemical contained therein, thereafter shredding the pulp ina bath of diluent to thoroughly and-intimately commingle the ibers of the pulp with the diluent to dissolve the chemical still contained` in the pulp, then again subjecting the pulp to pressure to substantially free it from such diluent whereby further chemicalwhichhas entered into solution with the diluent is removed from the pulp.

4. 'llhe herein described method which consists in compressing the pulpto squeeze out a portion of the chemical therefrom and sify shredding multaneou'sly forming the pulp into u sol web, feeding the web into a hath of dilueut,

the web and kneading the shredded fibers While in 'the hath to thoroughly and intimately admix theydiluent with such fibers of the pulp, then again com ressing the pulp to form it again into a soli web and to free it from the diluent and a, further portion of the chemical which entered` into soutiom with the diluent during the shredding endl kneading operations in testimony whereof l have signed the foregoing speeicatiom GTT@ MANTJIUS.

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