US3115098A

US3115098A - Stock inlet

Info

Publication number: US3115098A
Application number: US61136A
Authority: US
Inventors: Martin J Berlyn
Original assignee: Dominion Engineering Works Ltd
Current assignee: Dominion Engineering Works Ltd
Priority date: 1960-10-07
Filing date: 1960-10-07
Publication date: 1963-12-24
Anticipated expiration: 1980-12-24
Also published as: GB947350A

Description

Dec. 24, 1963 M. J. BERLYN 3,115,098

STOCK INLET Filed Oct 7, 1960 s Sheets-Sheet 1 INVENTOR.

MARTIN J. BEELYN M. J. BERLYN STOCK INLET Dec. 24, 1963 3 Sheets-Sheet 2 Filed Oct '7, 1960 INVENTOR.

M ARTI N J. BERLYN 4 j AT P/VE).

M. J. BERLYN Dec. 24, 1963 STOCK INLET 5 Sheets-Sheet 3 Filed Oct. 7, 1960 llllll {Anni}:lllulllllflil IT? m NEY ML mm /m I B H J m Y EB A M w w W m hkll United States Patent Oil-ice 3,ll5,b% Patented Dec. 24, 1963 3,115,098 FEETQQK ENLET Martin J. llerlyn, Montreal, Quebec, Canada, assignor to Dominion Engineering Works Limited Filed Get. 7, was, fier- No. 61,136 it) (Claims. (@l. TAB-113) This invention relates to new and improved stock supply means for an apparatus for forming pump stock into a sheet such as disclosed in my United States Patent 2,859,668.

In hydrolrinetic headboxes of the kind disclosed in my United States Patent 2,859,668 an annular mass of stock having a central core of air is whirled in a cylindrical casing by an impeller. Bubbles of air in the whirling annular mass of stock are centrifuged out and emerge at its inner periphery to join the central core of air, eventually passing out of the headbox to atmosphere. The amount of stock in the whirling annular mass is maintained substantially constant by provision of stock at a supply rate in excess of the headbox discharge rate, the excess leaving the headbox by way of a coaxial annular weir which controls the internal diameter of the whirling annular mass of stock. Stock supply means comprise an internal duct concentric with the impeller and provided with outlets adapted to feed stock to the inner periphery of the whirling annular mass uniformly along its length.

In operation of such stock supply means, streams of stock issuing from the duct outlets impinge on the inner periphery of the annular mass of stock and I have observed that this impact of stream upon mass, occuring at the boundary common to air and stock results in undesirable entrainment of air.

The object of this invention is to provide, for hydrolrinetic headboxes generally in accordance with my United States Patent 2,859,668, stock supply means characteris tically immune from tendency to entarin air in the stock.

Stock supply means in accordance with the instant invention comprise a duct concentric within the headbox impeller and having a plurality of extended outlet branches of which the discharge ends are at a radial distance from the axis of the duct greater than the radius of the annular weir which controls the internal diameter of the whirling annular mass of stock. The concentric duct is attached to, and rotates with, the headbox impeller.

Since the discharge ends of the extended outlet branches or" the rotating central duct are submerged in the whirling annular mass, supply of stock takes place beyond the boundary common to air and stock and is effected witl out impact and without entrainment of air.

Referring to the drawings:

P16. 1 is a side View of an apparatus embodying the invention;

FIG. 2 shows a transverse section of the headbox assembly in the plane 22 of FIG. 3; and

FIG. 3 shows a longitudinal section of the headbox assembly in the planes 33 of FIG. 1.

eferring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout, the device shown embodying the invention comprises casing l which is provided with an inlet 2 and a slice outlet 3. Casing 1 is also provided with extension for housing bearings 5 in which shaft 6 is journaled. An impeller assembly shown generally at 7 is attached to shaft 6. At the end of casing it remote from extension 4 is the annular weir or overflow member 0n the side of annular weir 3 remote from casing ]l is casing 9 which is provided with stock supply duct Jltl and overflow duct 3.2. Impeller assembly 7 is provided at one end with a flange fixed to shaft 6 and at its other end with an annular flange 14. Impeller vanes 15 are fixed at their ends to flanges 13 and 14 and are provided with reinforcing Webs 16. A central stock distributor duct 17 is fixed to flange 13. The end 13, of distributor duct 17 which is remote from flange 13 extends beyond annular Weir 3 and registers with, but does not touch, the end ll of supply duct 10, being separated from it by a small gap 19. Distributor duct 17 is provided with outlet branches 26 which are preferably, though not necessarily, half as many in number as the impeller vanes 15. Outlet branches or radial spokes 26) may be provided with tangential outlets or discharge ports 21. It will be noted that the tangential outlets or discharge ports 21 lie on a diameter larger than the inner diameter of the overflow member.

Stock is fed to the headbox through inlet 2 at a rate greater than the rate of discharge through slice outlet 3, the excess is discharged by way of annular weir 8, casing 9, and overflow duct 12.

The pressure of stock in supply duct It is maintained at a higher value than the pressure in casing 9 so that, where the stream of stock flowing from supply duct 10 into distributor duct 17 passes the small gap 19 between the end 11 of stationary supply duct ltl and the end is of rotating distributor duct 17, there is an outward leakage of stock through gap 19 into casing 9; this precludes admission of air to the stream of stock by way of gap 1%. Stock escaping from gap 19 joins the stock which flows over annular weir 8 and leaves casing 9 by way of overflow duct 12.

The operation of the device is believed apparent from the following:

In a Fourdriner paper machine, an aqueous suspension of cellulose fibre, known in the industry as stock, is discharged under pressure from a vessel called the headbox through a slit-like orifice known as the slice, onto a moving endless foraminous belt known as the wire.

The slice, whose function is to deposit stock on the moving wire evenly across its width, with minimum turbulence, is almost as wide as the wire.

It is difficult, but necessary, to achieve uniform flow rate at all points across the width of the slice. Velocity gradients impair proper formation of the sheet and give rise to a defective product.

In contemporary headboxes, the fluid pressure for discharging stock from the slice is derived from an external pump. Such headboxes tend to deliver stock from the lateral extremities of the slice opening at a lower velocity than from the centre; compensation is attempted by means of local adjustments of the opening of the slice lips, but this is at best a compromise falling short of ideal performance.

Another shortcoming of conventional headboxes is the occurrence of flocculation of fibres in zones of low veloc ity; to offset this tendency, mechanically actuated devices for evenly distributing the flow are incorporated, with concomitant sealing problems. In conventional headboxes, some ancillary device such as the deculator is employed for deareation of the stock; notwithstanding which, foaming sometimes occurs and has to be suppressed by means of a shower and/or addition of chemical defoamer to the stock.

In the device disclosed in my United States Patent 2,859,668, the pressure which ejects stock through the slice is developed entirely within the headbox itself by means of a rotating impeller externally driven through the medium of a shaft coaxial with the headbox and passing through one of its end walls. The transverse width of the slice is equal to the axial length of the impeller, whereby uniform discharge velocity across the entire width of the slice is provided. There are no zones of low velocity in the headbox itself and therefore no tendency to flocculation.

The rotating impeller is concentrically mounted within. and the slice outlet is tangential to, the cylindrical headbox. Rotation of the impeller is in that sense which urges stock directly towards the outlet with minimum change of direction.

This headbox may be regarded as a form of centrifugal pump, but while the stock rotated by the impeller is maintained centrifugally against the inner periphery of the casing, a concentric cylindrical internal void persists throughout its axial length.

An axial feed pipe, concentric with the impeller suppliesstock to the inside of the headbox at a flow rate greater than the rate of discharge from the slice. The amount by which supply rate exceeds discharge rate is by no means critical; it may be as little as 5% or it may be greater than without detriment to proper control of the internal void.

One end wall of the headbox is provided with a circular opening concentric with, and of substantially greater diameter than, the axial feed pipe, which passe through it. The lip of this opening functions as a circular weir over which excess stock escapes from the headbox, whereby the diameter of the cylindrical void is maintained substantially constant. Thus the mass of stock whirling in the headbox is in the form of a hollow cylinder of constant wall thickness, and the pressure available for ejection of stock from the slice is controlled entirely by the rotational speed of the impeller, since the central void and the free stream of stock issuing from the slice are both at atmospheric pressure.

According to my United States Patent 2,859,668, stock issues in free radial streams from orifices in the wall of the stationary axial feed pipe. These streams of stock impinge on the whirling hollow cylindrical mass or" stock at the interface between stock and air; the impingement is accompanied by violent turbulence at the interface, and entrainment of air in the stock takes place.

In the instant invention, that part of the axial feed pipe which is surrounded by the impeller is attached to, and rotates with, the impeller. Instead of orifices for the discharge of stock in free streams, the feed pipe, according to this invention, is provided with hollow spokes of such length that their outer ends are at a greater radial distance from the axis than the radius of the circular weir.

This is to say that stock from the axial feed pipe is introduced to the whirling hollow cylindrical mass of stock in the headbox by way of hollow spokes whose tips are submerged in stoclt, without shock and without disturbance of the interface between stock and air.

The volume of the mass of stock whirling in the headbox, which is constant, is so proportioned to the flow rate from the slice that the radially outward movement of an element of stock in the whirling mass is slower than the radially inward movement of air bubbles under centripetal force, whereby entrained air escapes from the stock at the void interface.

From the foregoing, it will be seen that I have provided new and improved means for obtaining all of the objects and advantages of the invention.

I claim:

1. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and having a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, an impeller coaxial with said casing and having a plurality of vanes, a hollow distributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow distributor duct into said casing, said distributor duct, spokes and vanes being mounted for rotary motion relative to said 4 casing, the w capacity of said stock sup ly means being greater than the how capacity of said slice outlet, said radial spokes discharging at a radius greater than the radius of said overflow control member, and having their ends submerged in the whirling mass.

2. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and having a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, an impeller coaxial with said casing and having a plurality of vanes, a hollow distributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow distributor duct into said casing, said distributor duct, spokes and vanes being mounted for rotary motion relative to said casing, the outside diameter of said hub being less than the inner diameter of said overflow control member, the flow capacity of said stock supply means being greater than the llow capacity of said slice outlet, said radial spokes discharging at a radius greater than the radius of said overflow con-- trol member, and having their ends submerged in the whirling mass.

3. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and having a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, an impeller coaxial with said casing and having a plurality of vanes, a hollow distributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow distributor duct into said casing, said distributor duct, spokes and vanes being mounted for rotary motion relative to said casing, said hollow radial spokes having tangential outlets, the flow capacity of said stock supply means being greater than the flow capacity of said slice outlet said radial spokes discharging at a radius greater than the radius of said overflow control member, and having their ends submerged in the whirling mass.

4. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and having a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, an impeller coaxial with said casing and having a plurality of vanes, a hollow distributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow distributor duct into said casing, said distributor duct, spokes and vanes being mounted for rotary motion relative to said casing, the outside diameter of said hub being less than the inner diameter of said overflow control member, said hollow radial spokes having tangential outlets, the flow capacity of said stock supply means being greater than the flow capacity of said slice outlet, said radial spokes discharging at a radius greater than the raduis of said overflow control member, and having their ends submerged in the whirling mass.

5. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and having a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, an impeller coaxial with said casing and having a plurality of vanes, a hollow distributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow distributor duct into said casing, said distributor duct, spokes and vanes being mounted for rotary motion relative to said casing, said hollow radial spokes having outlets tangential to said casing, said outlets lying on a diameter larger than the inner diameter of said overflow member, the flow capacity of said stock supply means being greater than the flow capacity of said slice outlet.

6. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and having a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, an impeller coaxial with said cas ing and having a plurality of vanes, a hollow distributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow distributor duct into said casing, said distributor duct, spokes and vanes being mounted for rotary motion relative to said casing, the outside diameter of said hub being less than the inner diameter of said overflow control member, said hollow radial spokes having outlets, said outlets tangential to said casing lying on a diameter larger than the inner diameter of said overflow member, the flow capacity of said stock supply means being greater than the flow capacity of said slice outlet.

7. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and having a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, an impeller coaxial with said casing and having a plurality of vanes, a hollow distributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow distributor duct into said casing, said distributor duct, spokes and vanes being mounted for rotary motion relative to said casing, said distributor duct having a portion extending axially beyond said overflow control member, the flow capacity of said stock supply means being greater than the flow capacity of said slice outlet, said radial spokes discharging at a radius greater than the radius of said overflow control member, and having their ends submerged in the whirling mass.

8. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and having a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, an impeller coaxial with said casing and having a plurality of vanes, a hollow dis tributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow distributor duct into said casing, said distributor duct, spokes and vanes being mounted for rotary motion relative to said casing, said distributor duct having a portion extending axially beyond said overflow control member and in adjacent relation and forming a pseudo seal with the adjacent end of said inlet member, the flow capacity of said stock supply means being greater than the flow capacity of said slice outlet, said radial spokes discharging at a radius greater than the radius of said overflow control member, and having their ends submerged in the whirling mass.

9. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and hav ing a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, an impeller coaxial with said casing and having a plurality of vanes, a hollow distributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow distributor duct into said casing, said distributor duct, spokes and vanes being mounted for rotary motion relative to said casing, the flow capacity of said stock supply means being greater than the flow capacity of said slice outlet, said radial spokes discharging at a radius greater than the radius of said overflow control member, and having their ends submerged in the whirling mass.

10. In a device of the character described, a substantially cylindrical casing having a longitudinal axis and having a tangential slice outlet, an inlet member coaxial with said casing and connecting said casing with stock supply means for supplying stock to said casing, an overflow control member coaxial with said casing and of greater diameter than said inlet member, a rotary impeller coaxial with said casing and having a plurality of vanes, a hollow distributor duct within said impeller and aligned with and adapted to receive stock from said inlet member, the outside diameter of said distributor duct being less than the inner diameter of said overflow control member, said distributor duct having a portion extending axially beyond said overflow control member and in adjacent relation and forming a pseudo seal with the adjacent end of said inlet member, said distributor duct having a plurality of hollow radial spokes for discharging stock from said hollow hub into said casing, said hollow radial spokes having outlets tangential to said casing and lying on a diameter larger than the inner diameter of said overflow member, said hub, spokes and vanes being mounted for rotary motion relative to said casing, the flow capacity of said stock supply means being greater than the flow capacity of said slice outlet.

References Cited in the file of this patent UNITED STATES PATENTS 1,026,075 Coombs May 14, 1912 1,139,042 Lehne et a1 May 11, 1915 1,143,957 Hansen June 22, 1915 1,150,686 Leblanc Aug. 17, 1915 2,216,542 Paige Oct. 1, 1940 2,344,281 Berry et al. Mar. 14, 1944 2,344,282 Berry et al. Mar. 14, 1944 2,419,905 Miess Apr. 29, 1947 2,489,079 Clark et al Nov. 22, 1949 2,859,668 Berlyn Nov. 11, 1958 2,868,097 Justice Jan. 6, 1959

Claims

1. IN A DEVICE OF THE CHARACTER DESCRIBED, A SUBSTANTIALLY CYLINDRICAL CASING HAVING A LONGITUDINAL AXIS AND HAVING A TANGENTIAL SLICE OUTLET, AN INLET MEMBER COAXIAL WITH SAID CASING AND CONNECTING SAID CASING WITH STOCK SUPPLY MEANS FOR SUPPLYING STOCK TO SAID CASING, AN OVERFLOW CONTROL MEMBER COAXIAL WITH SAID CASING AND OF GREATER DIAMETER THAN SAID INLET MEMBER, AN IMPELLER COAXIAL WITH SAID CASING AND HAVING A PLURALITY OF VANES, A HOLLOW DISTRIBUTOR DUCT WITHIN SAID IMPELLER AND ALIGNED WITH AND ADAPTED TO RECEIVE STOCK FROM SAID INLET MEMBER, SAID DISTRIBUTOR DUCT HAVING A PLURALITY OF HOLLOW RADIAL SPOKES FOR DISCHARGING STOCK FROM SAID HOLLOW DISTRIBUTOR DUCT INTO SAID CASING, SAID DISTRIBUTOR DUCT, SPOKES AND VANES BEING MOUNTED FOR ROTARY MOTION RELATIVE TO SAID CASING, THE FLOW CAPACITY OF SAID STOCK SUPPLY MEANS BEING GREATER THAN THE FLOW CAPACITY OF SAID SLICE OUTLET, SAID RADIAL SPOKES DISCHARGING AT A RADIUS GREATER THAN THE RADIUS OF SAID OVERFLOW CONTROL MEMBER, AND HAVING THEIR ENDS SUBMERGED IN THE WHIRLING MASS.