US2000268A - Hydration of pulp - Google Patents

Description

May 7, 1935. 1 G. s. WITHAM, JR

HYDRATON OF PULP Filed 0G13. 5, 1932 INVENTEJE @EUR E E.WI'TI-1AM-JR T'TCIRNEYE Patented May 7, 1935l UNITED STATES PATENT OFFICE HYDRATION 0F PULP George s. Witham, Jr.,l Lincoln, N. n.

Application October 5,

. 10 Claims.

My invention relates to paper making and more particularly to a means and method for treating paper stock.

Stock which consists wholly or largely f such materials as ground wood, esparto, straw, etc. and which is used in the cheaper classes of paper requires very little beating. On the other hand, stock for papers of the better class, such as writings, manilas, etc. in which such characteristics as strength, translucency or other special features are required, must be subjected to a prolonged beating process in order to attain the desired end, and it is Well recognized that the treatment to which the'stock is subjected in the beater has more to do with the quality of the finished paper than any other single step in the process of paper making.

In the beating of stock for papers of the better class a great deal of power is consumed and many means and methods of reducing this power consumption to a minimum have been suggested. Moreover because of the time factor involved and because of the necessity for providing the machine, with a continuous supply of properly treated stock, a great deal of iioor space is required for the beater equipment. Therefore, any

means or method of procedure whereby power consumption is lessened either by actually reducing the amount of power required per unit of time or by shortening the time during which the power must be expended will not only reduce cost, but if the time element can be shortened, the number of beaters necessary will be lessened and the floor space required therefor can be reduced.

Instead of treating the material in a beating engine, it has been proposed to project the stock under substantial pressure against a target so that the bundles of bers are eventually broken up by impact. Where the stock is subjected to this treatment alone the ends of the individual fibers are not frayed, brushed and combed out 'as they are in passing between the bed plate and roll of the beater and, therefore, are not reduced to the most desirable condition.

I propose to subject the stock to a combined beating and impacting treatment either successively or simultaneously, thereby not only securing the desirable effects of both treatments on the fibersI but producing a properly treated stock in a much shorter period of time. Especially with hard stock, the combined treatment, hereinafter outlined, will very substantially shorten the interva1 of time required to eiect a proper reduction.

1932, Serial No. 636,298

The objects of my invention, therefore, are to provide a novel means and method of treating paper stock whereby the time necessary to beat and properly reduce the stock is greatly shortened. Another object is to provide a means and 5 method whereby the stock may be very quickly A reduced to the desired degree of freeness without creating any appreciable volume of fine flufr` and fibers therein, and by means of which treatment the stock will'be softened to a degree where it 10 may be jordaned to any desirable extent with a minimum jordan input.

With these objects in view, my invention includes the novel method of procedure hereinafter described and the novel elements and the com- 15 binations and arrangements thereof described below and illustrated in the accompanying drawing in which- Fig. 1 is a side elevation view, partly in section, of one type of apparatus which I employ; 20

tub is the Hollander roll 5 provided with the 30 usual peripheral bars or blades 6 which cooperate with the bars in the bed plate 1. The tub is provided with a dump valve 8 actuated by the lever 9. Disposed below the beater is a chest III into which the stock from the tub is dumped through the pipe II. 'Ihis chest is preferably provided with a baii'ie I2 between the pipe I I and the intake pipe I3 of a centrifugal pump I4; the pump I4 being driven by motor I5. The pump discharges upwardly through the' piping system 40 I 6 which terminates in a section of pipe or header II extending transversely of the beater. In the embodiment illustrated in Fig. 1, the header is located above and slightly behind the Hollander roll. 'Ihis header is provided with a plurality of 45 outlets in the form of nozzles I8 directed so that they discharge against the b'eater roll.

In the ordinary or gravity type of beater, the rate of circulation for stock of a given density depends largely on the difference in static head between the stock at the rear of the roll and the stock at the front thereof. This in turn depends largely on the rate at which stock is lifted over the backfall by the action of the roll. Inasmuch as it is desirable to increase rather than decrease the rate of circulation through the beater it is desirable so to locate the nozzles through which the stock is projected into the beater that the major portion will ultimately fall or be discharged behind the backfall rather than in front of the roll.

In Fig. 2 I have shown a modification of the above described device in which the piping system I6 terminates in a header I9 located above and extending transversely of the beater tub. This header l 9 is provided with a nozzle plate 20 having a plurality of outlet nozzles or orifices 2| extending transversely of the beater and directed upwardly so that they discharge against a substantially unyielding surface or target such as the plate 22. 'Ihe plate 22 may be corrugated, serrated or otherwise roughened, if desired, and' may be mounted so that it is slidable vertically in suitable supports 23. A vertically extending threaded stem 24 attached to the plate cooperates with the hand wheels 25 whereby the target may be raised or lowered and its distance from the nozzles adjusted as desired.

In Fig. 3 I have shown a further modication of my device in which the piping system I6 terminates in a header 26 extending transversely of the beater tub and which is provided with a plurality of outlets in the form of nozzles 21. These nozzles are directed to discharge against an unyielding target 28 which may be similar to the target 22.

Since the stock is projected against these targets under substantial pressure and at high velocity they are preferably made of a wear and corrosion resistant alloy.

In operation, the beater is lled to a density of 5% or 6% in the usual manner and the stock is allowed to circulate at this density until it is completely and properly broken, teased and combed. The stock is then diluted to eiilcient pumping consistency by letting water into the beater. 'Ihis consistency is preferably from 4% to i1/2%. Pump I4 is then started and the dump valve 8 opened. The pump Il is preferably capable of producing a circulation of around `one thousand gallons per minute and developing pressures of from to 80 pounds at the nozzles. The stock under this pressure is projected at high velocity against the beater bars or-against the targets, as described above, and due 'to this impacting treatment, it is quickly hydrated.

This arrangement makes it possible, after havin'g broken the stock up just as necessary, to shut down the beater, pull the stock out from the front of the beater, discharge it into the back, and maintain a circulation of from 10 to 15 feet per minute. Where a very hard stock is being treated and in any case, if desired, the beater roll can be run in conjunction with the pump and a circulation of from 25 to 30 feet per minute obtained which results in a very much faster hydration.

One 'of the great advantages of this method of reducing hard stock lies in the fact that the material is reduced Without any cutting or iibrillation. For example, it is possible, without lowering the Hollander roll, to take the strongest, hardest, unbleached, western coast pulp and reduce it 100 points in freeness in approximately two hours and yet have a practically clear white water therefrom. This indicates that the reduction in freeness has been produced wholly by increased hydration or, in other words, by a softening of the stock whereby its capacity to retain water has been increased, rather than by the creation of a large amount of ne fluff in the stock indicative of broken, cut and crushed bers which result from slower but more drastic reducing treatments.

While I have described my invention in its preferred embodiments, it is to be understood that the words which I have used are words of description rather than of limitation, and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of my invention in its broader aspects.

What I claim is:

1. In a device for treating paper stock, the combination with a beating engine of the Hollander type including ,a tub and a roll rotatively mounted therein, of a nozzle directed to discharge against said roll, and a pump for delivering stock to said nozzle and discharging it therethrough against said roll at a velocity calculated to produce a substantial impact therewith whereby lbundles of fibres in said stock will be broken up.

2. In a device for treating paper stock, the combination with a beating engine of the Hollander type including a tub and a roll rotatively mounted therein, of a pump for withdrawing stock from said tub and discharging it against said roll at a velocity calculated to produce a substantial impact therewith and thereby break up bundles of bres in said stock.

, 3. In a device for treating paper stock, the combination with a beating engine of the Hollander type 'including a tub and a roll rotatively mounted therein, of a nozzle`directed to discharge against said roll, and a pump adapted to withdraw stock from said tub and discharge it through said nozzle against said roll at a velocity calculated to produce a substantial impact therewith and thereby break up bundles of bres in said stock.

4. In a device for treating paper stock, the combination with a beating engine of the Hollander type including a tub and a roll rotatively mounted therein, oi.' a nozzle directed to discharge against said roll in a zone rearwardly of the axis thereof, and a pump adapted to withdraw stock from said tub and discharge it through said nozzle against said roll at a velocity calculated to produce a substantial impact therewith and thereby break up bundles of fibres in said stock.

5. In a device for the treatment of paper stock, the combination with a beating engine of the Hollander type including a tub and a roll rotatively mounted therein, of a plurality of spaced nozzles directed to discharge against said roll, and a pump adapted to withdraw stock from said tub and discharge it through said nozzles against said roll at a velocity calculated to produce a substantial impact therewith and thereby break up bundles of fibres in said stock.

6. In a device for treating paper stock, the combination with a beating engine of the Hollander type including a tub and a roll rotatively mounted therein, of a target disposed to deflect stock projected against it into said tub, and a pump for withdrawing stock from said tub and projecting it against said target at a velocity calculated to produce a substantial impact therewith whereby bundles of fibres in said stock will be broken up.

'7. In a device for treating paper stock, the combination with a beating engine of the Hollander type including a tub and a roll rotatively mounted therein, of a pump for withdrawing stock fromv said tub in a zone in front of the axis of said roll and projecting it against a target disposed to the rear of the axis of said roll and at a velocity calculated to produce a substantial impact therewith whereby bundles of iibres in said stock will be broken up. j

8. In a device for treating paper stock, the combination with a beating engine of the Hollander type including a tub and a roll rotatively mounted therein, of a target disposed to deflect stock projected against it into said tub in a zone rearwardly of said roll, and a pump for withdrawing stock from said tub and projecting it against said target at a velocity calculated to produce a substantial impact therewith whereby bundles of fibres in said stock will be broken up,

9. 'I'he method of treating paper stock which comprises circulating the stock in a suitable receptacle, subjecting the' circulating stock to a brushing treatment whereby the ends of the individual bres are frayed and combed out, concurrently withdrawing stock from the circulating mass undergoing the brushing treatment and projecting it against a suitable target at a velocity calculated to produce a substantial impact therewith whereby to break up bundles of bres therein, and thereafter returning said stock to the circulating mass.

10. 'I'he method of treating paper stock which comprises circulating a body of stock in a suitable receptacle, subjecting the circulating stock to a brushing treatment during the circulation thereof whereby the ends of the individual ibes therein are frayed and combed out, concurrently withdrawing a portion of the stock from said body at one point and redeli'vering it to said body at another point,v and subjecting said withdrawn portion to an impacting treatment by projecting it against an appropriate target at a velocity adapted to break up bundles of ilbres therein upon impact therewith.

GEORGE S. WITHAM, Jn.

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