US1726749A

US1726749A - Device for controlling the moisture content of pulp

Info

Publication number: US1726749A
Authority: US
Inventors: George E Mayo
Original assignee: Individual
Current assignee: Individual
Priority date: 1928-10-01
Filing date: 1928-10-01
Publication date: 1929-09-03
Anticipated expiration: 1946-09-03

Description

` Sept'. 3, 1929. E MAYO 1,726,749

DEVICE FOR CONTROLLING THE MOISTURE CONTENT OF PULP Filed Oct. l, 1928 L'ttorncuS Paten-ted Sept. 3, 1929.

PATENT OFFICE.

UNITED STATES GEORGE E.V MAYO, F POTSDAM, NEW YORK.

Application filed October 1, 1928. Serial No. 309,669.

This invention relates to the art of paper making, and more particularly to improvements in moisture control devices employed for the purpose of maintaining a constant moisture content in pulp which is delivered to a Fourdrinier screen.

In the making of paper from pulp it is usual to employ a stuff box in which a constant level of pulp is maintained and from which pulp is fed to a refining engine or a Fourdrinier screen, the rate of feed or flow of pulp from the stuff box being controlled by some automatic device, improved types of such feed controlling devices being described in Letters Patent No. 1,248,97 2,

granted to I. J. Witham and myself and dated December 4, 1917, and in my copending application Serial No. 309,670, filed October In the above named copending application I have described how an air actuated mechanism connected to an air container suspended in a stuit' box and open at its lower end so that the pulp Will entrap an unchanging body of air in the container, the pressure of the air being determined by the density' of the pulp, which of course will vary with the variance in moisture content of the pulp, can be employed to regulate the feed from a stuff box and provide a constant rate of delivery oi solid material to the reiningengine or Fourdrinier screen, thereby assuring the formation of paper of uniform thickness,

Though I have found that by means ot: the

apparatus referred to it is possible to utilize the varying density of the pulp mixture to l actuate means for controlling the ow of pulp from the stud br, itis'y objectionable that variations in the moisture content of the pulp 4o be allowed to remain uncorrected, for such variations interfere with the uniform carrying out of the paper forming operations tak ing place after the pulp has left the stud box. It has long been recognized that 1t is desirable' that the pulp, when placed upon 4 the Fourdrinier screen, be of a definitely xed moisture content, and with this end in view numerous devices have been employed for adding water to the pulp as it leaves the stuii box in order to brin5 the pulp to the moisture content desired 'or further working, but all of such devices with which I am acquainted4 have been inaccurate and unreliable.

My present invention has as its main ob- ]ect the yovercoming of these disadvantages by the use of an air operated device and an air container for operating a valve to admit water to the pulp being delivered from a stuff box, the o eration of the invention being effected only y variations in the moisture content of the pulp in the stui' box.

Another object of my invention is to provide means for accurately indieatin the moisture content of the pulp in the stu box.

With these and other objects in View, the nature of which will more fully appear, the invention will be more clearly understood from a reading of the following detailed description, the appended claims, and the two views illustrated in the accompanying drawin s, in which:

igure 1 is a plan view of a stuff box embodying my invention, and

Figure 2 is a -central vertical sectional View, some parts being shown in elevation.

Like numerals designate corresponding parts in the two views illustrated.

In the drawings there is shown a receptacle or stuff box 1 containing a quantity of pulp 2 which is brought into the stuff box through an intake pipe 3 from a pump or other source of supply not sho-wn. An overflow partition 4C extending across the stuif box 1 serves to maintain a constant level of pulp therein. As the pulp is brought into the stu box at a greater rate than that at which it is used,'the excess pulp will overdow the partition and be caused to return to the source of supply through the return pipe 5. To provide for proper iiow of pulp from the stu` box to the Fourdrinier screen or refining engine, the stud box is provided with a discharge opening 6 which registers with a pulp dischar e pipe 7 secured to the stuii' box. The disc arge pipe may lead to the screen or refining engine as the case may be. A gate 8, adapted to slide vertically to control the discharge opening 6, is carried by the stuff box and may be provided with manually adjustable positioning means 9. Though for the sake of clearness I have illustrated this form of gate, its detailed construction forms no essential part of the resent invention and any suitable gate maye ernployed.

As stated above, the pulp entering the stuff box preparatory to being delivered to the Fourdrinier screen varies somewhat in moisture content, and for the purpose of introducing water to the pulp before delivery to the point of use I provide a water pipe 10 which extends through the pulp discharge pipe 7 as at 11, being thereby adapted to discharge into the pipe 7. The pipe 10 is connected with a source of water supply of constant pressure indicated at 10a. For controlling the rate at which water is discharged from the pipe 10 into the pipe 7, there is provided a valve 12 equipped with a valve lever 13 which is automatically operated by means to be hereinafter described.

An air container 14 is suspended within the stuff box 1, by any suitable means, suc'h as the brackets 15, and extends somewhat below the level of the pulp contained in the stuff box. This container is open to the pulp at a point below the level thereof, and preferably but not necessarily at its lower end, but is closed at its upper end by means of a plate 16, which plate may be provided with a flange 17 to facilitate attachment to the container 14.

As the description proceeds, it will become obvious that the cross sectional shape of the container 14 is of no importance, so that, while I have illustrated a container of cylindrical cross section, containers of other shapes could be used.

A diaphragm casing 18 is rigidly mounted upon the stuff box 1 by means of brackets 19 and contains a ressure responsive diaphragm 2O comprising a movable top plate 21, a stationary bottom plate 22, which is fixed to the bottom of the casing 18, and collapsible side walls 23. Though the bottom plate 22 is rigidly attached to the diaphragm casing 18, the top plate 21 and the side walls 23 are spaced from the casing and are free to move relative thereto.

The diaphragm chamber 24 communicates with the interior of the air container 14 through a pipe line 25 and an opening 26 in the diaphragm bottom plate 22, a manually operable valve 27 being interposed in the pipe line for shutting oit communication ofthe diaphragm chamber with the air container when desired.

A valve operating arm 28 is pivotally carried, as at v29, by a pair of brackets 30 on the diaphragm casing 18, and extends across and beyond the stuftn box 1. The outer end of the valve ,operating arm 28 is connected to the valve lever 1.3 by means of a link 31 pivoted to the said arm 28 as at 32 and to the valve lever 13 as at 33. It may be seen that, when the valve( operating arm is raised or lowered in a manner to be presently described, the valve 12 will be opened or closed in suitable degree to control the rate at which lwater is added to the pulp leaving the stuff In a manner to be fully explained when the operation of the invention is described,

the top plate 21 of the diaphragm will move upwardly when the moisture content of the pulp in the .stuft box increases and will move downwardly when the moisture content decreases. For making use of this movement of the .diaphragm top plate 21 to actuate the valve operating arm 28, there is provided a diaphragm lever 34 which is pivoted at one end as at 35 to a pair of lugs 36 on the casing 18, the other end of this diaphragm lever being formed with a boss 37 which extends through an opening in the top of the casing 18 and rests upon the top plate 21 to move up and down therewith.

The valve operating arm 28 overlies the diaphragm lever 34 and an abutment 38 is v slidably mounted on the valve operating arm 28 and may be secured in any position of ad justment by means of a set screw 39.` The abutment 38 rests upon the diaphragm lever 34 so that, when the said lever is caused to rise or fall, the valve operating arm 28 will likewise rise or fall to actuate the water valve 12. By changing the position of the abutment 38 relative to the

pivots

29 and 35, the amount of movement imparted to the valve operating arm 28 by a given movement of the diaphragm top plate 21 may be varied.

A number of weights 40 are adjustablyslidably carried by the valve operating arnl and serve to urge the outer end of lthe arm downwardly. v

A pressure gauge 41 is shown as mounted on the top plate 16 of the air container 14 and is arranged to communicate with the interior of the air container for actuation by the pressure of the air contained therein.

From-the foregoing, it is apparent that variationsin the moisture content of the pulp in the stuff box 1 will cause variations in the pressure of the air in the container 14, which in turn cause a movement of the diaphragm top plate 21, the diaphragm lever 34, the valve operating arm 28, and the valve level' 13 to vary the rate at which water is added to the pulp leaving the stuit box. However,

the complete manner of operation of the device may be briefly described as follows:

It is assumed that the valve 27 has been opened to allow the diaphragm chamber 24 to communicate with the air container 14 and that the gate 8 is closed. Pulp will be then introduced into the stuff box 1 through the pipe 3, and, as the pulp rises in the stuft' box, it will entrap a quantity of air in the container 14. lVhen the pulp on the outside of the container has reached the level of the overflow partition 4, it will flow over this partition and thereby be maintained ata constant level in the stuit box. Due to the pressure exerted by the column of pulp in the stuft' box, some of the pulp will rise within the air container 14 and will compress the entrapped air therein, the rising of the pulp inside of the container stopping at such a level that the pressure exerted by entrapped and compressed air just balances the pressure due to the otherwise unbalanced head of pulp indicated at h. It is also assumed that the moisture content of the pulp when delivered to the stuff box is slightly lower than the moisture content desired when the pulp is delivered to the Fourdrinier screen, and that the pulp to be continuously brought into the stuit box through the pipe 3 will always have this slightly reduced moisture content. The reason for this will become apparent when it is pointed out that, though water may be added to pulp the moisture content of which is too low, it would not be possible to'remove water from pulp having too high a moisture content.

The pulp in the stuff box being of the above described slightly reduced moisture content, the sliding abutment 38 and the weights 4() are then adjusted along the valve operating arm so as to cause the valve 12 to allow just sufficient Water to enter the pulp discharge pipe 7 to bring the moisture content of the pulp in the pipe up to the proper working point. The positions in which the weights must be placed in order to so balance the valve operating arm that the valve will allow just enough water to ow through the pipe 10 to bring the mixture to the desired moisture content may be determined by trial; and, if desired, the positions then marked on the valve operating arm for future reference. In order to determine the correct positions of the weights, the gate 8 is opened and samples of the pulp passing through the pipe 7 taken from the pipe 7 in advance of the water pipe 10 and then tested for moisture content. After a few of such samples have been tested, the positions of the weights will be changed until the desired moisture content of the pulp leaving the pipe 7 is obtained. Thus, if a higher moisture content is desired', the weights Will be moved to the y left as viewed in the drawings, whereas if a lower moisture content is desired the weights will be moved to the right. It is to be understood that it is not necessary that such tests be made each time the stuff box is caused to start delivering pulp through the pipe 10. After these preliminary adjustments have been once made and it is desired to supply pulp mixture of a predetermined moisture content to the Fourdrinier screen, it is only necessaryto open the gate 8 to permit discharge from the. stul box at the desired rate.

As long as the moisture content of the pulp entering the stuff box remains the same, the pressure of the air in the container 14 will remain the same and there will be no change in the setting of the valve 12, so that, -for a .iixed moisture content of the pulp entering the stui" box, water will be added to the leav- 1ng pulp at a constant rate.

If the moisture content of the pulp in the stuff box increases beyond the value for which the apparatus was initially set, the density of the pulp stock will increase, since water has a higher specic gravity than the solid material used. This increase in density will result in a greater upward pressure being exerted by the pulp due to the head of pulp indicated at h, and the level of the pulp within the container will rise until the entrapped air has been compressed to such a degree as will balance the diminished head of pulp h. The increased pressure of the air in the container acts through the pipe 25 and on the under sidev of the diaphragm plate 21, raising the plate, which, by means of the diaphragm lever 34, the valve operating arm 28, and the link 31, will move the valve lever 13 to close the valve 12 to diminish the rate at which water is added to pulp in the pipe 7.

In a similar manner, when the moisture content of the pulp in the stui box decreases below the value for which the apparatus was initially set, the density of the pulp will be decreased and the valve 12 will be opened to increase the rate'at Which Water is added to the pulp in the pipe 7.

By a proper adjustment of the abutment 38 and the weights 40 it will be possible to deiinitely fix the rate at which water will jge added to the pulp as it leaves the stuff The gauge 41, being actuated by air under pressure in the air container 14, can be calibrated to accurately indicate the moisture content of the pulp in the stud box, since the pressure in the container is dependent only upon the relative amounts of solid material and water in the pulp,

It is apparent that I have provided a device Which may be used to control the moisture content of pulp preparatory to its be-l ing delivered to a Fourdrinier screen or reiinino' engine in such a wa as to compensate Ior any variations in tlie moisture content of the pulp as delivered from the mixer. Though simple in constructionand operation, my device is capable of fine adjustment and is very reliable, since for its operation it depends only upon the moisture content of the pulp in the stuff box, and not upon any outside influences which might be subject to continued variations tending to reduce the eliiciency of the device.

It is to be understood that the details of structure and arrangement of parts ma bo variously changed without departing rom the spirit and scope of my invention as pointed out in the appended claims.

I claim:

1'. In a device for controlling the moisture content of pulp, the combination with a stu box having a discharge opening of means for adding water to the pulp before delivery at the point of use, comprising a pipe connected to a source of water supply, means for controlling the discharge of the water from said pipe, and means for operating said controlling means comprising an air container confining an unchanging body of air therein and open to the pulp at a point below its level in the stuff box, and pressure responsive means communicating with the container and actuated by the pressure of the air confined therein for actuating said controlling means to regulate the flow of water from said pipe.

2. In a device for controlling the moisture content of pulp, the combination with a stuff box having a discharge opening of means for adding water to the pulp before delivery at the point of use, comprising a pipe connected to a source of water supply, means for controlling the discharge of the water from said pipe, and means for operating said controlling means comprising a fluid container condsning an unchanging body of iuid therein and open to the pulp at a point below its level in the stuff box, and pressure responsive means communicating with the container and actuated by the pressure of the fiuid confined therein for actuating said controlling means to regulate the flow of water from said pipe.

3. In ay device for controlling the 1noisture content of pulp, the combination with a stuff box having means for maintaining a constant level of pulp therein, and a discharge opening of means for adding water to the pulp before delivery at the point of use, ,comprising a pipe connected to a source of water supply, means for controlling the discharge of the water from said pipe, and means for operating said controlling means comprising an air container confining an unchanging body of air therein and open to the pulp at a point below its level in the stuff box, and pressure responsive means communicating with the container and actuated by the pressure of the air confined therein for actuating said controlling means lo regulate the iiow of water from said pipe.

4. In a device for controlling the moisture content of pulp, the combination with a stufT box having a discharge opening` of means for adding water to the pulp before delivery at the point of use, comprising a water pipe line connected to a source of water supply and adapted to discharge into the pulp before delivery at the point of use. a valve in said pipe line for controlling the discharge, and means for operating the valve comprising an air container confining an unchanging body of air therein and open to the pulp at a point below its level in the stuff box. and pressure responsive means communicating with the container and actuated by the pressure of the air confined therein for actuating said con- 'trolling means to regulate the flow of water from said pipe.

5. In a device for controlling the moisture content of pulp, the combination with a stuff box ha-ving a discharge opening of means for adding water to the pulp before delivery at the point of use, comprising a water pipe line connected to a source of water supply and adapted to discharge into the pulp before delivery at the point of use, a valve on said pipe line for controlling the discharge, and means for operating the valve comprising an air container confining an unchanging body of air therein and open to the pulp at a point below its, level in the stuff box, pressure responsive means communicating with the container and actuated by the pressure of the air confined therein, and adjustable means connected to the valve and to said pressure responsive means for operating the valve when the pressure responsive means is actuated.

6. In a device for controlling the moisture content of pulp, the combination with a stuff box having a discharge opening of means for adding water to the pulp before delivery at the point of use, comprising a Water pipe line connected to a source of water supply and adapted to discharge into the pulp before delivery at the point of use, a valve in said pipe line for controlling the discharge, and means for operating the valve comprising an air container confining an unchanging body of air therein and open to the pulp at a point below its level in the stuff box, pressure responsive means communicating with the container and actuated by the pressure of the air confined therein, a valve operating arm, and means adjustably positioned on the arm and actuated by the pressure responsive means for operating the arm and the valve.

7. In a device for controlling the moisture content of pulp, the combination with a stuff box having a discharge opening of means'for adding water to the pulp before delivery at the point of use, comprising a water pipe line connected to a source of water supply and adapted to discharge into the pulp before delivery at the point of use. a valve in said pipe line for controlling the discharge, and means for operating the valve comprising an air container confining an unchanging body of air therein and open to the pulp at a point be* low its level in the stuff box, pressure responsive means communicating with the container and actuated by the pressure of the air confined therein, a valve operating arm, means adjustably positioned on the arm and actuated by the pressure responsive means for operating the arm and the valve, and weights adjustably positioned on the arm and serving to urge it downwardly. v

8. In a device for controlling the moisture content of pulp, the combination with a stui:l box having a discharge opening of means for adding water to the pulp before delivery at the point of use, comprismg a Water pipe line connected to a source of water supply and adapted to discharge into the pulp before delivery at the point of use, a valve in said pipe line for controlling the discharge, and means for operating the valve comprising an air container confining an unchanging body of air therein andopen to the pulp at a point below its level in the stulf box, a pressure re.

sponsive diaphragm communicating with the container and actuated by the pressure of the air contained therein, a pivoted diaphragm lever adapted to be actuated by contact with the diaphragm, a pivoted valve operating arm overlying the diaphragm arm, an abutment adjustably positioned on the valve operating arm for contact with the diaphragm lever, and means connecting the valve operating arm to the valve at a point remote from the pivot on said arm.

9. In a device for controlling the moisture content of pulp, the combination with a stuff box having a discharge opening of means for adding water to the pulp before delivery at the point of use, comprising a water pipe line connected to a source of water supply and adapted to discharge into the pulp before delivery at the point of use, a valve in said pipe line for controlling the discharge, and means for operating the valve comprising an air container confining an unchanging body of air therein and open to the pulp at a point below its level in the stui box, a pressure responsive diaphragm communicating with the container and actuated by the pressure of the air contained therein, a pivoted diaphragm lever adapted to be actuated by contact with the diaphragm, a pivoted valve operating arm overlying the diaphragm arm, an abutment adj ustably positioned on the valve operating arm for contact with the diaphragm lever, means connecting the valve operating arm to the valve at a point remote from the pivot on said arm, and adjustable means for urging the valve operating arm downwardly.

1 0. In a device for controlling the moisture content of pulp, the combination with a stuff box having a discharge opening of means for adding water to the pulp before delivery at the point of use, comprising a pipe connected to a source of water supply, means for controlling the discharge of the water from said pipe, and means for operating said controlling means comprising an air'container confining an unchanging body of air therein and open to the pulp at a point below its level in the stu box, and pressure responsive means communicating with the container and actuated by the'pressure of the air confined therein for actuating said controlling means to regulate the flow of water from said pipe, and a gauge communicating with the container and responsive to the pressure therein for indicating the moisture content of the pulp in the stuff box.

11. In a device for controlling the moisture content of pulp wherein is provided a stui box having a discharge opening and means for adding water to the pulp before delivery at the point of use, means to trap an unchanging body of fluid in a manner for having its pressure varied in accordance with variations in the moisture content of the pulp in the stul box, and means actuated by the pressure of the said body of fluid to control the rate at which water is added to the pulp by said water adding means.

12. In a device for controlling the moisture content of pulp, the combination with a stuft1 box having means for maintaining a constant level of pulp therein and a pulp discharge opening, of a pipe connected to a source of water suppl and adapted to discharge into the pulp befbre delivery at the point of use, a valve in said pipe for controlling the discharge therefrom, a pressure actuated diaphragm, a fluid trap open at one point to communication with the pulp in the stuffbox beneath the level thereof, and at another point with the diaphragm, and closed throughout otherwise to entrap therein an unchanging body of fluid in a manner for causing the pressure of the entrapped fluid to vary in accordance with variations in the moisture content of the pulp in the stud box, and means connected to the control Valve and actuated by the diaphragm to open or close tllevalve accordingly as the moisture content of the pulp in the stu' box varies. v

13. In apparatus for controlling the ratio of solid'to liquid in pulp delivered for use, a receptacle into which the pulp is delivered, solid and moisture ratio controlling means, a container open at one end and immersed in the pulp to entrap a body of fluid therein so that its pressure will be varied as the consistency of the pulp varies, pressure actuated devises comprising a pressure responsive diaphragm communicating with the container and actuated by the pressure of the air contained therein, a pivoteddiaphragm lever adapted to be actuated by contact with the diaphragm, a pivoted operating arm, and an abutment adj ustably positioned on the operating arm for contact With the diaphragm lever, said operating arm being connected with the said controlling means for the purpose specified.

14. In a device for delivering pul of a constant moisture content, a receptac e into which pulp is delivered having a moisture content less than that required at the point of use, means for automatically supplying consistency of the pulp, pressure actuated devices associated With the Water supplying means and with the air trapping member, and

a. gauge communicating with the air trapping 5 member for indicating the moisture content in the pulp. y

15. In a device for controlling the moisture content of pulp, a pulp receptacle into which pulp is fed and from which it is discharged for use, an air container suspended in said receptacle, a Water supply pipe from which Water is delivered into the pulp discharge from the receptacle, and means operated by the air pressure in said container for varying the amount of Water delivered from the pipe.

In testimony whereof, I have hereunto subscribed my name.

GEORGE E. MAYO.