US2509822A - Stock inlet - Google Patents

Description

May 30, 19450 L. HoRNBosTEL 2,509,822

sToQK INLET Filed Dec. 21, 194e Patented May 30, 1950 UNITED STATES PATENT FFICE 2,509,822 s'roox m'LE'r Lloyd Hornbostel, Beloit, Wis., assignor to Beloit Iron Works, Beloit, Wis., a corporation of Wisconsin 12 Claims.

This invention relates to a stock inlet for paper making machinery, and particularly deals with a, head box or inlet chamber construction that will maintain a. predetermined constant level of paper stock therein.

The velocity of paper stock at the slice of a paper making machine is determined by the total pressure head of the stock. This total pressure head is produced by the pressure on the stock plus the head of stock above the slice. To maintain optimum iiow conditions for a chosen flow rate of stock onto the paper machine forming surface, it is highly desirable to hold a constant level of stock in the stock inlet. As the stock flow rates are changed during operation of a paper making machine, diierent stock levels in the stock inlet should be maintained for optimum operation.

According to this invention a stock inlet denes a closed stock chamber with an outlet slice at the forward bottom edge thereof immediately adjacent the breast roll of a Fourdrinier-type paper making machine, a, stock feed at the lower rear portion thereof, and a compressed gas feed at the upper portion thereof. The chamber is partially filled with stock by the feed and the atmosphere above the Istock in the chamber is sulpplied with a compressed gas such as air so that the pond of stock in the chamber is under superatmospheric pressure. The stock will spout out through the slice opening onto the forming surface of the paper making machine. For eicient paper making, the rate of flow of the spouting stock must be maintained quite constant for any given type of stock and speed of machine operation. Since, as explained above, the flow rate is determined by head Ipressure and air or gas pressure on the stock, variations of either of these pressures will change the flow rate, thereby changing the web-forming conditions on the forming surface of the paper machine; Further, flow of stock in the chamber itself influences the web-forming' conditions and, since the flow in the chamber varies with variation in level of stock, it is desirable to maintain a/constant level in the chamber.

Alternatively, instead of creating superatmospheric pressures on the stock pond, in some instances maintenance of reduced pressures is preferred. The reduced pressure on the stock will hold a suiiicient head of stock in the inlet box to cover rectier rolls and the like therein, even when a very slow slice discharge is wanted and could not be obtained with a head of stock ber.

2 tillat is high enough to cover the rolls and the This invention provides a simple, inexpensive control which automatically compensates for variation in stock feed and gas feed into or vacuum pull on the chamber and automatically maintains a constant level of stock in the cham- The automatic control consists of an orice in the stock chamber at the level desired for the stock. Air and stock bleed through this orifice, and can conveniently be fed into the white water collecting system of the paper making machine. When reduced pressure on the stock is wanted, a vacuum pump is connected to the orice through a separator chamber which receives stock draining through the orifice. When the stock feed increases, to raise the level in the chamber, the orifice is submerged in stock. Under these conditions, air pressure above the stock will increase, thereby creating a greater resistance to the stock feed and automatically slowing down the stock feed until the desired stock level is reclaimed, whereupon the orifice will only be partially submerged in stock, and both stock and air will bleed through the orifice. When the stock feed slows up too much, to cause the stock level to drop, the entire orifice will be uncovered and air pressure in the chamber will be directly vented to the atmosphere, whereupon the decreased air pressure will decrease the resistance to stock feed and again the stock level will be reclaimed. If the air pressure drops.

the stock level will rise, thereby closing the orince and cutting oli the air vent whereupon the air pressure will build up to force a lowering of the stock level.

It is, then, an object of this linvention to provide a simple means for automatically controlling stock level in the head box of a paper making machine irrespective of changes in stock feed conditions.

A further object of the invention is to maintain a constant flow rate for stock issuing from a stock inlet by automatically maintaining a constant level of stock in a chamber of the inlet.

A still further object of this invention is to provide a stock inlet for a. paper making machine wherein a predetermined flow rate is maintained at the slice by automatically venting pressured air and pressured stock to the atmosphere through an orice at a level selected for optimum stock level operation.

A further object of the invention is to provide a stock inlet for a paper making machine having a closed stock chamber equipped with an outlet orifice at a level desired for a pond of stock in the chamber, and having a stock feed and a pressured air feed automatically controlled by said orifice to maintain the selected stock level in the chamber. l

Another object of the invention is to provide a closed head ybox for a Fourdrinier-type paper making machine with an arrangement that automatically controls air pressure and stock feed pressure by selectively bleeding stock and air through an orice.

Another object of the invention is to provide a stock level control for a head box which includes an orifice at the desired level for stock, a separator connected with the orifice, a vacuum pump exhausting the separator, and a barometric or water leg drain for the separator. I

Other and further objects of the invention will be apparent to those skilled in the art from the following detailed description of the annexed sheet of drawings which, by way of a preferred example only, illustrates one embodiment of the invention.

On the drawings:

Figure 1 is a somewhat diagrammatic side elevational view, with parts in vertical cross section, of a Fourdrinier-type paper making machine equipped with a stock inlet having a level control arrangement according to this invention.

Figure 2 is a fragmentary vertical cross-sectional view, with parts in end elevation, taken along the line lil-l1 of Figure l.

Figure 3 is a fragmentary diagrammatic side view of a Fcurdrinier-type paper making machine equipped with a stock inlet having a vacuum type level control according to an alternate form of this invention.

As shown on the drawings:

As shown in Figure l, the reference numeral I designates generally a stock inlet or head box for a Fourdrinier-type paper making machine including a forming wire II trained between a breast roll I2 and a couch roll I3 to have a horizontal upper run Ila and a bottom run IIb. The box I0 supplies stock to the upper Vrun II a of the wire II at the breast roll end of this run, and white water from the stock drains through both runs of the wire into a pit I4 which, in turn, drains through a pipe I5 into a stock-mixing chestll supplied with fresh stock from a feed pipe I1. The mixed stock and white water is pumped from the chest rI6 by a pump I8 through a pipe-line i8 having branches Isa and I9b on opposite sides of the box I0 but at a level beneath the bottom of the box. These branches I9a and I 9b supply a iiow evener 20, better illustrated and described in my copending application Serial No. 679,420 filed June 26, 1946, entitled: "Flow evener." 'I'his ow evener 20 is a box extending across thefull width of the head box III beneath the head box and has a partition wall 2| therein coactin-g with the walls thereof to define parallel side by side flow passages 22 and 23. A rectifier roll 24 is rotatably mounted in the evener above the baille 2l and the top of the evener box has a slot along the length thereof partially receiving the upper end of the rectifier roll 24. Stock is -fed into the opposite end of the passageways 22 and .23 to flow in countercurrent directions along the lengths of these passageways and through the rectifier roll 24 to the outlet slot 25 in the top of the box.

'I'he head box I0 has a bottom wall 26 substantially level with the upper run Ila of the forming wire Il and extending rearwardly from the breast roll I2. Vertical side walls 21 extend upwardly from the sides of the bottom wall 2i and a back wall 23 is provided between the side walls. A front wall 2l is also provided between the side walls 21 at the front end of the box and overlies the upper run Ila of the forming wire at the top of the breast roll I2. top of the box is also closed by a top wall 30 which preferably has an opening 30a therein sealed by a door 3l. An inlet pipe 32 for compressed air or other gas from a pump 33 communicates through the top wall 30 to introduce `lgressured air to the chamber 34 defined by the vA sump portion 3l is provided in the bottom of the box and extends across the full width thereof at the rear end of the box. This sump 35 communicates along the length of its ttom with the slot 25 of the flow evener 20 and mmunicates along the length of its top with. the bottom of the chamber 34. A horizontal baille 38 is mounted on top of the bottom wall 28 and projects over the top of the sump 3l to selectively control the width of a gap 31 between the top of the sump and the bottom of the chamber 34. 'Ihe baille 3B is preferably adjustable to vary the width of the gap 31.

An apron 33 is mounted on the bottom' wall 2B and projects forwardly therefrom to overlie the upper run IIa of the forming wire II on the breast roll I2.

A slice 39 depends from the bottom of the front wall 29 in spaced relation over the top run Ila of the wire Il, and is adjustably mounted on this front wall 23 to vary the size of a slice outlet 40 at the front lower edge of the box I0. This outlet 40 extends across the full width of the upper run II a of the forming wire.

Paper stock pumped through the :dow evener 20 ows through the slot 25 and gap 31 into the chamber 34 to form a pond P in the chamber 34. This pond supplies the outlet 40 and, as explained above, for optimum web-forming conditions, the level of the pond should remain constant for a given flow rate of discharge.

In order to maintain a preselected constant level, one of the side walls 21 of the box I3 is equipped with one or more orifices or holes 4I. These orifices are at different levels and only one of them, at the level desired for stock in the pond, is used. As shown in Figure 2, plugs 42 close the orifices that are not being used. A drain tube 43 connects the open orifice 4I with the pit I4.

The selected orifice 4I vents air and stock from the chamber 34 at the level desired for the pond P in the chamber. As shown in Figure 1. the level of the pond P is about midway between the top and bottom of the middle orifice 4I. Since the chamber 34 is closed except at the slice outlet 40 and the orince 4 I, since it is desired to maintain a constant now rate through the outlet 4I for any given condition voi.' paper machine operation, and since it is also desired to maintain a predetermined level of stock for the pond P, the oriiice 4I will vent both air and stock from the chamber 34 through the tube 43 where the stock is collected in the pit I4, and the air is released to the atmosphere.

If the pump I8 feedsstock to the pond P at too fast a rate, so that the level of the pond rises, the orifice 4I will be submerged whereupon air pressure above the pond will increase since the pump 33 will continue to force air into the now unvented air space above the pond. The increased air pressure will increase resistance to the pump i8, thereby slowing up the delivery rate of the pump. If the delivery rate slows down too much, so that the level of the pond drops, the orifice 4I is completely uncovered and air pressure is vented to the atmosphere, thereby decreasing the resistance to the pump I8 and permitting the stock level to rise. If air pressure from the pump 33 decreases or increases, the resistance to the pump I8 decreases or increases to vary the level of the pond P, whereupon a. balanced condition is only obtained when the orifice 4I is partially submerged to vent both stock and air through the tube 43.

In the arrangement shown in Figure 3, parts corresponding with parts shown in Figure l, and described hereinabove, have been marked with the same reference numerals. In Figure 3, the stock inlet or head box Ilia has the oriiice 4I in the back wall 23 connected through a tube or .pipe 50 with the upper portion of a closed separator tank I. A vacuum pump 52 has the suction side thereof connected through a tube 53 with the top of tank 5I. A pipe 54 extends downwardly from the bottom of tank 5| to discharge in the white water pit I4 at a level beneath the level L of white water in the pit. A rectiiler roll 55 is mounted in the head box Illa adjacent the slice outlet 40 and receives stock therethrough as it i'lows to the outlet 40.

When the paper machine is run slowly, to form a heavy weight sheet S on the wire run Ila, the head H of stock in the pond P suillcient to cover the roll 55 would normally cause too great a stock discharge velocity at the slice opening 40. Since the roll 55 must be completely submerged in stock, this head H is required.

The effect of the head H on the velocity oi the stock flowing through the slice outlet 40 is controlled by evacuating the separator 5| thereby pulling a vacuum through the orifice 4| to decrease pressure in the chamber 34. 'I'he separator 5| is sealed by the barometric leg effect of the submerged drain pipe 54.

For example, when it is necessary to carry one foot more head H in the pond P than that required for producing the proper velocity at the slice outlet 40, the vacuum pump 52 is driven to hold a vacuum of about one inch of mercury in the chamber space 34 above the stock pond P. This will raise the water in the pipe 54 about one foot higher than the level L in the pit I4. If the pond P then rises to cover the orifice 4I, only stock water will be pulled into the separator, and no air would be pulled from the space in the chamber 34 above the pond P. As a result, the Water level would be lowered to uncover the orifice 4l whereby air will be pulled from the chamber 34 to hold the water level at the orice. Aconstant level is thereby automatically maintained as with the use of compressed gas described above, but the head pressure effect of the stock at the slice outlet is diminished to produce the desired stock discharge velocity.

From the above descriptions it should be understood that the stock inlet or head box of this invention receives stock merged from two oppositely ilowing streams, maintains a pond of this stock under superatmospheric pressure or under sub-atmospheric pressure, an`d discharges the pressured stock from the pond at a constant preselected rate under a, slice outlet. The level of the stock in the pond is maintained constant irrespective of fluctuations in stock feed rate and air pressure by means of an orifice arrangement at the level desired for stock in the pond. This orince is partially submerged to vent both air and stock to the atmosphere or to a vacuum pump, and when the stock level changes to either uncover the oriilce or totally submerge the orifice, then the resistance to inlet feed of stock is automatically varied to reclaim the preselected stock level.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. A stock inlet for a paper making machine which comprises structure deilning a clo ed chamber having a discharge outlet arranged o deposit stock on the forming surface of a paper machine, a cross-ow stock feed evener arranged to discharge upwardly into the lower portion of said chamber at a point remote from said outlet, said evener having a pair of flow passages extending across the full width of said closed chamber, a rectifier roll rotatably mounted in said evener and communicating along its length with both passages, said evener having a discharge slot communicating with the top of said rectifier roll/along the length of the roll and across the width of the closed chamber for feeding stock from the evener to the lower portion of the chamber, closed conduit means for supplying stock under head pressure to opposite ends of said passages for cross ow along the lengths of the passages and for upward ow through the rectier roll and discharge slot to rise toward the top of the closed chamber, a pump arranged to control pressure in the chamber above the stock therein, and a small outlet opening in said chamber at a-level desired for stock in the chamber, said outlet opening being arranged to discharge stock when the level rises above the outlet .opening thereby automatically increasing the pressure in the chamber to depress the level of the stock, and said outlet opening being arranged to discharge gas from the chamber when the level of the stock drops below said outlet opening to automatically reduce the pressure in the chamber thereby effecting a rise in the level of the stock.

2. A stock inlet for a paper making machine which comprises structure defining a closed chamber having a discharge outlet arranged to deposit stock on the forming surface of a paper machine and a stock inlet remote from said discharge outlet arranged to flow stock under head pressure into the lower portion of the chamber for forming a pond of'stock in the chamber, a pump acting on the interior of said chamber to control pressure in the chamber, and said structure having a small outlet opening at a level desired for stock in the chamber and arranged to selectively bleed stock or gas from the chamber to automatically regulate the gas pressure in the chamber and maintain the stock at the desired stock level.

3. In a stock inlet having a head box defining a closed chamber with an outlet at the lower forward end thereof, an inlet sump at the lower rear end thereof, a cross flow box beneath the sump and communicating therewith through an elongated discharge slot, and closed conduit means for feeding stock into opposite ends of the cross flow box to create therein oppositely flowing streams of stock and to feed said stock to said sump and chamber through said slot, the improvements of a wall on said head box having an orifice venting thesaid closed chamber to the atmosphere at a level desired for a pond of stock in the closed chamber, pump means forintroducing gas under pressure into the top of the closed chamber, and additional pump means discharging stock into said closed conduit means for pressurizing stock through said closed conduit means into opposite ends of the flow box whereby the level of said stock relative to said orifice will control the resistance to operation of both of said pump means to automatically maintain a level of stock in said closed chamber intermediate the top and bottom of said orifice thereby producing a constant ow rate of stock through said outlet at the lower forward end of the box.

. 4. In a paper making machine including a head box defining a closed stock chamber, a. forming wire arranged for receiving stock from said closed chamber, collection means receiving drainage from said forming wire, a stock mixing chest receiving the drainage from said collection means, means for supplying fresh stock to said mixing chest, a cross flow box communicating with the closed stock chamber of said head box at the bottom portion of the closed stock chamber, a pump for forcing stock from said mixing chest, a closed conduit conveying stock forced from the pump to said cross flow box for flow into said closed chamber of said head box, a second pump for introducing compressed gas into said closed chamber of the head box above the stock therein, said closed chamber of the head box having a vent at a level desired for a pond of stock in the head box and arranged to selectively bleed compressed gas and stock from said closed chamber to balance both of said pump means for maintaining stock at said level, and a conduit connecting said vent with said collection means,

5. A stock inlet for a paper making machine comprising structure defining a closed stock chamber having a slice outlet at the front end thereof, a closed conduit for introducing Stock into the lower portion of the stock chamber in spaced relation from said slice outlet, a compressed air inlet for introducing air into the upper portion of the closed stock chamber, vent means communicating with the interior of said closed stock chamber at a level desired for stock in the chamber, first pump means for pumping stock through said closed conduit, second pump means' for introducing air through said air inlet, and said vent means controlling resistance to both of said pump means for balancing pressure inthe closed stock chamber to maintain the stock level at the vent means.

6. A stock inlet comprising structure defining a closed stock chamber having an adjustable discharge outlet at the front end thereof, a closed conduit for introducing stock into the lower portion of the stock chamber in spaced relation from said discharge outlet, a compressed gas inlet for introducing a gas into the upper portion of the closed stock chamber, a first pump for pumping stock through said closed conduit, a second pump for pumping a gas into said compressed gas inlet, an atmospheric vent communicating with the interior of said closed stock chamber at a level desired for stock in the chamber, and said vent being constructed and arranged to bleed stock and gas from the chamber in balanced proportions to maintain the level of stock at the vent level.

7. A closed stock inlet for a paper making machine having a forming surface, comprising means defining a closed stock chamber, a white water collector beneath said forming surface, "a stockv supply pipe, a stock mixing chest receiving white water from the collector and stock from the supply pipe, a pump for feeding admixed stock and white water along a closed path kto the closed chamber of said inlet, a second pump for compressing air into said closed chamber of the inlet, and a vent in said closed chamber of said inlet at a level desired for stock therein, said white water collector being connected with said vent whereby said vent will bleed compressed air and stock from the closed chamber of the inlet in proportions to maintain the stock level at the vent means.

8. A paper machine stock inlet comprising means defining a closed stock chamber having a stock feed inlet and a stock discharge outlet, said means having an orifice at a level above the stock feed inlet and discharge outlet and at a level desired for stock in the chamber, a separator tank connected with said orifice, means for evacuating i tank, and a barometric leg drain for said 9. In a paper making machine having a forming wire with a drain pit therebelow, a closed stock box having an outlet at the front end thereof for feeding stock onto said wire, means for introducing stock under head pressure into the lower portion of said closed stock box in spaced relation from said outlet, said closed stock box having an orifice at a level desired for, a pond of stock therein, means for introducing gas under e pressure to the upper portion of the closed head box, said orice adapted to bleed stock and gas from said stock box in balanced proportions to maintain a level of stock at the orifice level, and conduit means connecting the orice with the drain pit.

10. In a paper making machine having a forming wire with a drain pit therebelow, a closed stock box having an outlet for feeding stock to the wire and an inlet spaced from said outlet for re ceiving stock, means for feeding stock under head pressure through said inlet into said closed stock box, said box having an orifice at a level desired for a pond of stock therein, a separator tank, a tube connecting said orifice with the upper portion of said tank, a drain tube extending from the bottom of said tank to said pit and arranged to be submerged in water in the pit, and a vacuum pump connected to the top of said tank, said orifice being arranged to vent stock and atmosphere above the stock in said stock box to maintain the level of stock in the box at the orifice.

11. A stock feed device for a paper making machine comprising a, closed head box having a stock inlet and a stock outlet in spaced relation with a closed chamber therebetween, means for feeding stock under head pressure through said stock inlet into said closed chamber, said closed chamber of the head box having a vent at a level desired for stock therein, and a mechanical pressure creating device controlled by said vent for regulating the absolute pressure in the head box above the stock therein to thereby maintain the stock level at said vent.

12. A stock feed device for maintaining desired flow conditions for selected rates of now which comprises structure defining a closed stock chamber, a slice outlet for said chamber, a stock inlet for said chamber remote from said outlet, means for feeding stock under head pressure through said inlet to create a pond of stock in e said chamber, said chamber having a vent at a REFERENQES CNED level desired for stock in the chamber and a' me' The following references are of record in the chanical pressure creating device controlled by me of this patent: said vent for regulating absolute pressure in said head box and thereby control the level of the 5 UNITEDSTATES PATENTS stock within a narrow range adjacent the level Number Name Date of the vent for maintaining the desired stock 2,186,761 Malkin. Jan. 9, 1940 ilow conditions for the selected flow rate inde-l 2,202,890 Berry June 4, 1940 pendent of the volume of stock ilowing through 2,347,717 Staege May 2, 1944 the chamber. l0 2,347,850 Staege May 2, 1944 LLOYD HORNBOSTEL. 2,381,286 Hornbostel et al Aug.' 7, 1945

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