US3184375A - Pulp approach flow system for headboxes of paper-making machines - Google Patents

Description

May 18, 1965 P. SIEGEL ETAL 3,184,375

PULP APPROACH FLOW SYSTEM FOR HEADBOXES OF PAPER-MAKING MACHINES Filed April 22, 1963 Wyn/r0195 Peter .fi'zfgel #Jem Clzley France, both firms Filed Apr. 22, 1963, Ser. No. 274,444 Claims priority, applicationzgrance, Apr. 21, 1962,

1 Claim. 61. 162-343) This invention relates to a novel pulp approach flow system or distributing apparatus for distributing and directing pulp to headboxes of paper-making machines.

The pulp, a very diluted or attenuated suspension of cellulose fibers, is fed to the paper-making machines by an approach flow system and a headbox. The pulp is distributed over the entire working width of the machines in the form of a liquid stream of uniform thickness and is admitted at a uniform speed, because irregularities in thickness of the admitted stream of pulp result in corresponding irregularities in the thickness of the paper.

It has been proposed to distribute the flow of pulp which is fed to the headbox by means of a plurality of branched pipe conduits, each of a generally Y-shaped configuration, the outlet portions of the conduits forming a row of parallel and closely adjacent elements. The pulp stream produced in this manner was, however, not uniform in thickness because slight irregularities at the outlet between two branches of the first distributing apparatus have a considerable effect on the outlet of the final distributing apparatus dependent thereon.

The object of the invention is therefore to produce a pulp approach flow system or distributing system which entirely meets the requirements set forth above.

According to a first feature of the invention the pulp distributing system or apparatus has a plurality of Venturi tubes which are vertical or inclined and distributed at the same height and at uniform distances apart over the entire working width of the paper-making machine, the Venturi tubes being mounted on a narrow plup distributing conduit and extended in upward direction by flattening and widening taper sleeves arranged with the narrow sides of their rectangular discharge openings at the same height and closely adjoining each other thereby forming a common discharge opening extending over the full working width of the machine. The cross-sectional constriction at the necks of the Venturi tubes is such that in the range of flow rates contemplated, a turbulent flow is obtained.

With the apparatus described a variation in the thickness of the liquid stream, that is a change in the discharge speed at one of the flattening and widening taper sleeves, involves a far greater change in the speed at the Venturi neck where the passage cross section is very restricted and the flow therefore takes place in a turbulent manner and with considerable change in the frictional losses in the following riser which is formed by the upper parts of each Venturi tube and the taper sleeve extending therefrom. The Venturi tubes therefore perform the function of static flow regulators, provided that they are fed substantially uniformly, and they thus deliver a liquid stream of constant thickness, discharged in lamellar form. The turbulent zone in the Venturi tubes has also the advantage that an intermediate thorough mixing of the pulp takes place therein which renders its structure more uniform, whereas subsequently in the widening taper sleeves a uniform orientation of the fibers is attained in that they tend to arrange themselves in line.

According to a second feature of the invention the mouth of a pulp admission conduit is arranged on the pulp distributing conduit carrying the Venturi tubes, in

United States Patent ice the middle and at the point of the greatest internal diameter thereof at a short distance from and opposite a vertical rear wall of the pulp distributing conduit.

Due to this arrangement the admitted liquid stream is spread in uniform thickness and at a constant speed in all directions and properly distributed over the two halves of the pulp distributing conduit and the Venturi tubes.

According to a third feature of the invention the pulp admission conduit is of triangular cross section already before terminating in the pulp distributing conduit, a flat face of the triangle being located horizontally and downwardly.

As a result the pulp stream fed to the pulp approach flow apparatus is divided into a strong carrier bottom current and a lighter top current, the bottom current carrying the pulp right up to the extreme ends of the two halves of the pulp distributing conduit.

According to a fourth feature of the invention the two halves of the pulp distributing conduit taper toward their extremities in that the bottom of the pulp distributing conduit extends upwardly toward these points.

According to a fifth feature of the invention parts of a roof of the pulp distribtuing conduit located between outlet pipe connections leading into the Venturi tubes can, while being at the same height, be arranged parallel to the upwardly extending bottom, and transverse walls can be arranged between the deepest points of these roof parts and the Venturi tube pipe connections so as to lead into these pipe connections.

Through the inclined roof parts the cross section of each half of the pulp distributing conduit is tapered in steps and consequently proportionately stepped for the Venturi tubes and equal portions of the pulp are deflected upwardly into the Venturi tubes by the transverse walls.

The various features provided according to the invention on and in the pulp distributing conduit exert a continuously changing inifuence and insure that all the Venturi tubes are fed absolutely uniformly and consequently the most favourable conditions are provided for obtaining a completely uniform final pulp stream.

A preferred embodiment of the invention will now be described by way of example and with reference to the accompanying drawing, in which:

FIG. 1 is a vertical section taken transversely of the longitudinal axis of the paper-making machine, and

FIG. 2 is a vertical section taken on the line II-II of FIG. 1 and in the longitudinal axis of the paper-making machine.

FIG. 2 shows a vat or container 1 in which the pulp is maintained at a constant level 2. The pulp in the form of a suspension of, for example, five to fifteen grams of cellulose to one liter of water, can be fed to the pulp approach flow or distributing apparatus 4 directly from the container 1 or with the aid of a pump of suitable power. The admission of the pulp is eifected through a conduit 3 which, with the object of obtaining a farreaching bottom current, is given a cross section substantially in the form of a triangle with one of its flat sides located horizontally and terminates in the middle of the narrow pulp distributing apparatus 4 at right angles to a rear vertical wall 4:: thereof at a short distance from the wall. The pulp passes through the conduit 3 at a speed of several meters per second into the pulp distributing apparatus 4 which is constructed in the form of a conduit. By the fact that the pulp strikes against the vertical wall 4a of the pulp conduit 4 it is uniformly distributed over the two halves of the pulp conduit 4. At the top of the pulp conduit 4 a plurality, for example six, outlet pipe connections 40 are arranged at the same height and at uniform distances apart. The parts of the roof of the pulp conduit 4 between the pipe connections 4c may be located horizontally and at the same height.

of the machine.

On the other hand, there may also be provided roof parts 4d which are at-the same height but parallel to the bottorn 4b of the pulp conduit 4, to which they become closer in steps toward the ends of the box. At their lowest points the roof parts 4d are defined by transverse walls 4e leading into the outlet pipe connections 4c and conducting the individual streams of pulp upwardly into the pipefconnections 4c. on which Venturi tubes 5 are.

the appended claim rather than by the foregoing descripmounted; The cross section. at the necks of the Venturi tubes;5,' as an example, is selected arbitrarily atonev third of their inlet cross section. The Venturitubes 5 are extended at their upper ends by flattening and widening taper sleeves 6 having discharge openings 'or outlets 6:: located in longitudinal direction at a commonlevel if with their narrow ends directly adjoining each other so' that they form together a long and narrow common discharge opening extending over the entire working width InZthe taper sleeves 6 the speed is re duced and converted into pressure .and the outflow becomes laminar. Above this commondischar'ge opening there is a sill7 over which a thin pulp stream 18, in laminated state and of great width, finallypasses out. 1

To permit a uniformity of speed' to be ensured in the individual taper sleeves 6 these can be provided at their ends with bleeding devices 9 for controlling the pressure.

To enable the thickness of the pulp stream 8 to be varied, bleeders are provided on the breast box 4,.for, example a slide valve 10 in: the middle thereof .and a slide valve 11 at each end thereof. The quantities of pulp removed are returned into the system by suitable pumps. 7 a

In addition, the apparatus according to the invention affords the following advantages: The conversion of the the pulp distributing system or conduit 4 are easily action and all changes which come within-the meaning and range of equivalency of the claim ar'etherefore-intended to be embraced therein. I

'Weclaim:

An approach flow system for a headbox of a papermaking machine comprisingin combination an admission conduit having a cross-section in the form of a triangle standing on a horizontal base side, the angles adjacent the base side being equal to each other, the admission conduit opening medially into, a pulp. distributing conduit of said system through a first verticaljwall thereof, said conduit being rectangularin longitudinal section and including a second vertical wall in spaced opposed relationship to said first vertical wall, said second vertical wall being relatively close to. said first verticalwall, said conduit including opposed top and bottom walls, said conduit being inclined upwardly from the medial portion thereof to opposite extremities, a plurality of outlet pipe connectionsconnected to and projecting upwardly from said top wall, said pipe connection being in parallelspaced 40: and control because it is fitted with a headbox 13 having a v cover 12 and by lifting the cover 12 on the headbox 13 the inner walls of the taper sleeves 6,-theVenturi tubes 5 and relationship and in substantially the same common hori- -zontal'plane, and a Venturi tube, connected toeach pipe connection and, merging in a generally common opening into a headbox. v f

i 7, References Cited by tlievExaminerj 5 UNITED STATES PATENTS 2,782,692

2/57 "Boronow'et al. l62-.339

2,894,581" 7/59 GoumenioukQ. 162-343 3,055,421

9/62 Cirrito l62340 OTHER REFERENCES Van Der Meer, Hydraulics of Flowbox and Slice, j TAPPI, vol. 3 7, No. 11, November 1954, pp. 502-511.

'DONALL H. SYLVESTER, Primary Examiner.

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