US1203240A - Pulp-beater. - Google Patents

Description

A. MUIRHEAD.

PULP HEATER.

APPLlcATloN man MAY7,1915.

Patented Oct. 31, 1916.

2 SHEETS-SHEET i.

A.v MUIRHEAD.

vPULP BEATER.

APPLICATION FILED MAY 7, 1915.

Patnted Oct. 81, l916.

2 SHEETS-SHEET 2.

Inven i narran stares rarnnr onirica ANDREWMUIRHEAD, or Havant-tint, MASSACHUSETTS.

PULP-BEATER.

Specification of Letters Patent.

Patented ct. 31, 1916,

Application filed May 7, 1915. Serial No. 26,643. l

roll, it is a well-known fact that the nearer` any particular portion of the pulp happens to be traveling to the midfeather, the more frequently will it pass beneath the beatingroll, on account of the shorter course which it has to travel in making the circuit, so that if the relative positions of the different portions of the pulp are unchanged, those portions nearest the midfeather will be beaten much faster than the portions next the sides of the tub, and ,for this reason it is usually necessary for an attendant to stir the contents of the tub frequently, so that the beating action thereon will be more nearly uniform.

It is customary to heat the contents of the tub by discharging steam into it closely adjacent one end ofthe midfeather, and as a result, the pulp is not uniformly heated, the portion nearer the midfeather being heated to a much higher temperature than the portion nearer the sides, and, as it is usually considered preferable to discharge the steam jetdownward, the jet has an action to retard the flow of the pulp.

ln the ordinary operation ofA a pulp beater, the pulp tends to accumulate at the back fall, and, when the pulp is particularly heavy, or the percentage of water therein is low, so that the circulation in the beater is particularly sluggish, or does not start readily, thepulp frequently overflows the sides of the tub at this point. Moreover the pulp level is, ordinarily',,considerablyy higher adjacent the back fall than elsewhere, so that to prevent the accumulation at the back fall `would. be to increase the capacity of the tub. While it is a fact that the rapid-y ity of the beating yoperation increases as the rapidity of circulation increases, and that', within limits, the` greater the percentage of water in the pulp the more rapidly will it be circulated, yet it is also a fact that the greater proportion of material to be beaten to the water, the more the quantity of material which will be beaten for a certain volume of pulp passing beneath the roll. It follows therefore that, under ordinary conditions, the gain which will be secured by reducing the proportion of water is partly lost by the increased slowness with which c the pulp will be made to circulate by the beating roll, 'while the gain made by increasing the proportion of water is partly lost by the decrease in quantity of pulp ground,

but, if the speed of circulation may be increased, and at the same time, the proportion ofmaterial to the water may berincreased, it will be obvious that the rapidity of the beating operation will be increased for both reasons. lt .is also well known that,

in the ordinary operation of a pulp beater, portions of the pulp frequently lodge at ditierent points in the tub and are not moved by the ordinary circulation therein, so that frequent stirring by hand is necessary to dislodge such portions. It is customary, after the pulp has been beaten for a certain length of time, to refine it still further by passing it through a Jordan engine. There are numerous objections to this operation, principally on account'of the time lost and power required and the danger of cutting the fibens.

The objects of my invention are to improve the operation of the ordinary pulp beater, so that uneven grinding of the pulp is avoided, and the use of hand stirrers is made i'lnnecessary, to increase the production of such pulp beaters, by inducing a more rapid vilow of the stuffl therein without increasing, but at the same time reducing the proportion of water therein; to cause a more uniform and rapid heating' of the pulp in the beater, without retarding, but rather accelerating the flow therein; and to make unnecessary, kin many instances, at least, the

use of a Jordan engine, so that the beating operation will be finished when the pulp is discharged from the beater, thereby further reducingthe time required for the beating operation. l accomplish these objects by providing, in connectionv with an ordinary pulp-beater, means for withdrawing a portion of the pulp from the tub, preferably at points where 1t tends to clog or accumulate,

that is, adjacent the back fall, and forcibly returning it thereto at such points and in such directions as to cause the flow of the entire contents of the tub tol be accelerated, and particularly to cause the flow of the portions thereof more nearly adjacent the sides of the tub, to be accelerated, to a much Vgreater extent than those portions more nearly adjacent the midfeathcr, so that the proportion of water to the stock may be reduced, thereby increasing the speed of the beating operation and enabling the stock to be beaten with greater uniformity, and without resorting to hand stirring; further by directing a et of steam into the by-pass pipe through which the pulp is circulated outside the tub, so that the pulp flowing through the by-pass is heated, and its flow therethrough is accelerated, and the entire contents of the tub is heated by the heated pulp discharged, therein; furtherby providing a form of circulating pump in said bypass, which has a beating action on the pulp, as well as a pumping action, so that it performs the further refining usually performed by the Jordan engine and greatly assists the operation of the beater roll.

For a more complete understanding of my invention reference is made to the accompanying drawing-in which;

Figure l is a side elevation, and Fig. 2

is a plan view of a pulp-beating apparatus made according to my invention.J Fig. 3 is a longitudinal central sectional view of a combined circulating and beating-pump which I preferably employ. Fig. et is a cross-sectional view thereof', on the line ct-a of Fig; 3. Fig. 5 is a detail view of one side ofthe pump casing. Fig. G is a detail sectional-.view of a peripheral portion of the pump-casing. Fig. 7 is a detail view, showing the coperative action of the impeller and the peripheral portion of the casing. Fig. 8 is a detail edge elevation of the impeller. Fig. 9 is an enlarged sectional View on the line ZJ-) of Fig. 1. Fig. 10 is a longitudinal sectional view on the line c-c of Fig. 9. Figs. 11 and 12 are detail sectional views ofthe inlet nozzles.

In the drawing a pulp-beater of ordinary and well-known construction is illustrated, said beater comprising an oblong shaped tub 1, having its side-walls rounded at its ends and providedk with a midfe'ather 2 between 'which and one side of the tub, the ordinary back-fall, this particular point of connection being desirable though not essential, although I do consider it practically essential to have this point of connection adjacent the back fall. Said pipe G is extended to a centrifugal pump 7, the particular construction of which will be hereinafter more fully described, a right-angular fitting 8 being'.

provided therein adjacent the point where it leads to the central inlet 0f the pumpcasing. The tangential discharge pipe'9, of the pump-7, is connected by a pipe 10, which will be hereinafter more particularly described, to the inlet of a second centrifugal pump 11, of, preferably, indentically the same construction as the pump 7, and the tangential discharge pipe 12, from the pump 11, is connected to a goosenecky pipe 13, which is, in turn, connected to a Yi-coupling 14, from which branch pipes 14a', 14b 'extendand are connected to fittings land 15, respectively.V As shown in Figs.l 11 and 12, said fittings are bolted to the outer sidesofthe tub and have nozzles 15", 15 on'their inner sides, which project through apertures in the sides of the tub, and havetheir ends terminating flush with the inner sides thereof, said nozzles being arranged in alinement with the passages through said fittings, to which said pipes 14111, 141 are connected. Said fittings are preferably arranged at different elevations and the `nozzles aty different angles withk relation to the sides of the tub,

the nozzle of the uppermost fitting 15 being directed at a more acute angle than the lowermost, the angle being such that a jet directed therefrom will be carried, if un'- obstructed, to points adjacent and beyond the opposite end of the midfeather, while that of the lowermost' nozzle is directed at an angle of approximately 45 to the side, so that a jet discharged therefrom will, if unobstructed, strike against the midfeather near its end adjacent the back-fall. `While this particular arrangement of nozzles is desirable under some conditions, I do not consider it the most satisfactory underV other conditions. That is, different sizes of tubs and different kinds of stock require different arrangements of nozzles. For example, the arrangement indicated in dotted lines in Fig. 2 is desirable under some conditions.

A steam-pipe 16 is connected t0 the middle of the fitting 8 in a position to direct a jet of steam into the inletV to the pump 7 in alinementtherewith, as best shown in Fig. 3.v The particular form of circulatingpump,- indicatedin a general way by the characters 7 and 11, which I preferably employ, is more particularly'shown in detail in Figs. 3 to 8. Said pump comprises a shaft 18, which extends centrally with relation tothe side walls 19 and 20, of the pump casing,

Athe wall 19 having a central opening to whichthe fitting 8 is connected, the shaft extending througha similar; opening in the wall 20. A peripheral wall 21 is interposed between the end-walls 19and 20, the disends of said radial ribs.

charge-pipe 9 leading tangentially therefrom, as shown in Fig. 4. The impeller 22 is mounted kon the shaft 18, to rotate within the casing, and is provided with a series of rearwardly curved blades 2:2, which are in general form, similar to those employed in a well-,known form of centrifugal pump. The blades 22a are of approximately uniform width throughout their entire length, and are ofl somewhat V-shaped form in cross section, so that each blade is transversely and longitudinally convex on its working side and is provided with two working-faces 22h, at said side which are arranged at an obtuse angle to eachother, said faces meeting in the center line of the iinpeller and being inclined rearwardly from this point, with relation to the direction of rotation.-

The end-walls 19 and 2O areV provided with a series of radially extending ribs 9.5, and the peripheral wall 2lV with a series of transverse ribs 26, which extend `from the Each of said transverse ribs comprises two portions arranged at an angle with relation to each other, said angle corresponding to the angle between the faces 22", and meeting in the center r,of the casing, so that the vertices of the angles between said ribs and between the workingfaces of the impeller-blades meet in the same plane. The angles of said faces are ar ranged oppositcly with relation to the angles of said ribs 26, as best shown in Fig. 7. The horizontal portion of the pipe lOwhich eX- tends between the two pumps is preferably provided with a series of spirally extending ribs 30 which are formed much after the manner of the rifiing of a gun, as best shown in Figs. 9 and l0. A valve 31 is provided in the pipe 6 adjacent the tub, and yvalves 32 and 33 are provided in the branches-ler, 14;b to close or ,regulate the flow therethrough. f

The operation of the apparatus, as a whole, is as follows: The tub is' filled and the beating operation is carried on in the ordinary manner, until the largerlumps or bunches of stock are broken up. The valves 31, 32 and 33 are then opened and the pumps 7 and 1l are operated, sothat the pulp is drawn from the tub through the pipe 6 into the pump 7, which forces it through the rifled-pipe l0, where it is given a whirling action, into the second pump l1, which in turn causes a forcible discharge thereof through the pipe lhbranchpipes 14, 14h, and from the nozzles 15b, l5", back into the tub of the beater. The pulp is thus forced into the tub in the direction of the normal flow of the pulp, but at an oblique angle thereto, the discharge from the upper nozzle 15b being much more nearly in that direction than that from the other nozzle l5, as particularly shown in Figs. ll and l2.

It will be apparentthat, as the jets from both nozzles are discharged into a body of water, the force thereof will be dissipated in affecting an acceleration of the fiow of the pulp in the tub. It will further be ap parent that the accelerating force will be greatest at the end of the nozzle, from which point it will rapidly decrease until it is finally dissipated. As a result the accelerating action on the pulp flowing in the beater will be the greatest on that portion nearest the side-walls, and such action will decrease in force from that point, so that the accelerating force on that portion next the midfeather will be comparatively slight or inappreciable, according to the forcey with which the pulp is discharged into the tub.

f As a result, the flow of the ,different portions ofthe pulp is accelerated in proportion to the increased length of the path which such portions have to travel in making the circuit about the midfeather, so that the portions of the pulp nearer the side wall will. be

caused to make a complete circuit in ap-y proximately the saine time as the portions nearer the midfeather, with the result that one portion of the pulp will not be beaten substantially more rapidly than another, thereby obviating the necessity of stirring the pulp to prevent uneven beating.

lVith the arrangement of nozzles, above described, the discharge from the one entering the tub at the more acute angle, 151" is effective approximately to the feed end of the midfeather. -The purpose of the other jet 15c is, particularly, to prevent lodgment of masses of the pulp on the bottomand especially in the angle between the bottom and the midfeather, and by having the discharge in a direction morenearly at right angles to the flow, the force of the jet ywill not be spent before it reaches the midfeather, so that pulp accumulating against the midfeather willbe dislodged. By adjusting the valves 32 and 33 the relative effect of the jets may be varied according to conditions, or as desired. It will be apparent, for example, as indicated in dotted lines in Fig. 2, that differently arranged jets, will have somewhat different effects, in detail, although the general effect will be the saine.

By locating the entrance to the by-pass pipe adjacent the back fall, the tendency of the ypulp kto accumulate to a higher level and tooverfow at this point, is prevented, and as the accumulation of pulp at this point is prevented, and the pulp is maintained at a more nearly uniform level, the excess at the baclefall is removedk and delivered at points where the level would otherwise be lower. As the flow of the pulp ,in the tub is greatly accelerated by the force of the discharge through the by-pass, it be comes practicable to reduce the proportion of water to the material below that which is advantageous when the above described arrangement is not employed, so that it is thereby possible both to reduce the time taken to beat a charge properly, and also to increase the amount of material beaten at each charge, most substantially. As the pulp is circulated through the by-pass pipes, as above described, steam is forced into the circulating pulp thereby assisting the pumps in circulating the pulp, and at the same time uniformly heating the pulp which passes through said pipe. The pulp thus heated is thoroughly mixed with the pulp in the tub, when returned thereto, so that all portions of the pulp will be heated with substantial uni- -formity.

An ordinary centrifugal pump, employed in the above relation is effective in breaking up the bunches of stock and performing to a substantial extent, a beating operation, the effectiveness thereof, in this regard, depending, to a considerable extent, on the character of the pulp operated on. However, l preferably construct the pumps 7 and 1l, so that they will have a much greater beating action than would an ordinary centrifugal pump. To this end said pumps are provided with said internal ribs 25 and 2G, and the impeller blades are constructed to pass in close proximity thereto, but the spaces therebetween are purposely made somewhat greater than the space which would be provided between the impeller and the casing under ordinary circumstances. As the impeller revolves, the stock will be thrown into the spaces between the ribs, and portions thereof will be drawn between the ribs and blades, before it is discharged, so that the same brushing or beating action will take place as in the beater, or as in a Jordan engine. The centrifugal action of the impeller forces a portion of the stock against the peripheral portion of the casing, while, on account of the convex shape of the working faces of the blades, or the arrangement of said faces, so that they slope away from the middle line thereof, with relation to their direction of rotation, there is also a strong tendency to cause the stock to be forced against the side walls of the casing, so that a considera-ble portion thereof will be drawn between the blade edges and the ribs, and any portions too large to pass between them will be carried through the discharge port. As the stock will pass through two of these pumps before it is returned to the beater, it will be beaten or disintegrated to a considerable extent by the time it is returned to the tub, thus greatly assisting in the beating operation. As the pulp passes through the pipe l0, as it is conducted from one pump to the other, it will be ca-used to have a whirling or rotary motion, which will also be effective in further disintegrating the stock.

through the pipe 1G,l

The above described operation is contin-V ued until the entire mass of pulp has been reduced to the desired state, and as the refining action of the pumps is substantially the same as that of the Jordan engine, the use of such a machine is rendered unnecessary and the whole operation is performed much more rapidly than when the Jordan engine must be employed, while the time re` quired for the operation in the beater is also greatly reduced, as before stated.

I claim l. A pulp-beater having a circulating passage, and a beating-roll arranged to cause circulation through said passage in a predeterminedV direction, a by-pass connected to said passage, and means to cause independent circulation through said by-pass, said by-pass being arranged to withdraw the pulp from said passage at one point and return it thereto 'at another, and having its discharge end arranged to direct a jet in a direction to cause acceleration of the flow in said passage. Y

2. A kpulp beater having a circulating passage and a beating roll to cause circulation through said passage in a predetermined direction, a by-pass connected to said Vpassage at remote points, and means to cause circulation through said by-pass, the discharge end of said by-pass being arranged to discharge a jet therefrom in the direc-V tion of and obliquely to said direction of flow in said passage.

3. A pulp beater having a mid-feather and a circulating passage extending about said mid-feather, a beating roll for causing circulation in said passage, a by-pass connected at its ends to said passage, and means to cause circulation through said by-pass, the discharge' end thereof being located in the side wall of the tub and arranged to direct a jet across said passage in the direction of and'obliquely to the direction of flow therein.

a. A pulp beater having a horizontally disposed circulating passage and a beating roll arranged to circulate the pulp therein, a byepass leading from said passage at one point and returning thereto at the outer side of the passage at a distance from said point, and arranged to direct a jet obliquely across said passage and in the direction of the flow p therein, and means to force the pulp in said passage through said by-pass to accelerate the flow in said passage to a decreasing ex-v tent from the outer side thereof inwardly.

5. A pulp beater having a horizontally disposed circulating passage, a mid-feather about which said passage extends, and a beating roll in said passage at one side of said mid-feather to cause circulation therethrough in a predetermined direction, a-bypass leading from said passage and returning thereto at the outer side of the portion of the passage at the opposite side of the midf feather from said roll, the discharge end of said ley-pass being arranged to direct a jet obliquely to the flow in said passage and in the direction thereof, to accelerate the flow of the pulp in said passage to a decreasing extent from the outer side inwardly.

6. A pulp beater having a circulating passage, a by-pass connected thereto and having means therein to cause circulation therethrough, to Withdraw a portion of the pulp from the tub and forcibly return it thereto, a plurality of discharge nozzles connected to the discharge end of said by-pass arranged to cause the pulp to be forced back into the tub at different points, and to .accelerate the flow in said passage by the force of such discharge.

7. A pulp beater having a circulating passage and a beating roll arranged to circulate pulp therein, a by-pass connected to said passage at different points, and having means, independent of said roll, to cause circulation therein, the outlet end of said by-pass being branched to provide a plurality of discharge nozzles, said nozzles being arranged to direct jets into said passage, in the direction of the flow therein, and at different relative angles.

8. A pulp beater having a circulating passage through which the pulp iiows in a predetermined direction, a by-pass connected to said passage at different points, and means to discharge a steam jet into said byspass in the direction of the flow therein.

9. In combination with a pulp beater having a circulating passage, a by-pass connected to said passage at different points, a rotary pump in said by-pass for causing circulation therethrough, said pump coniprising a casing having end and peripheral wall-portions, said end-Wall portions hav ing radially extending internally projecting ribs, and an impeller having radially extending blades, the side edges of said blades Abeing arranged to move in cooperative relation With said ribs to perform a combined pumping and beating action.

In testimony whereof, I have signed my name to this specication.

ANDREW MUIRHEAD.

Witness L. H. HARRIMAN.

Copies of this patent may be obtained for five centsreach, by addressing the Commissioner of Patents, Washington, D. G.

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