US2815763A - Paper stock consistency regulation - Google Patents

Description

Dec. 10, 1957 J R. FANSELOW 2,815,763

PAPER STOCK CONSISTENCY REGULATION Filed llarch 4, 1954 3 Sheets-Sheet 1 .Dlai'ion 0&1 are and cficfmi'or Beaisr INVENTOR. J0/z n fi finselozzr 5 J. R. FANSELOW 2,815,763

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United States Patent PAPER STOCK CON SISTENCY REGULATION John R. Fanselow, Appleton, Wis., assignor, by mesne assignments, to Kimberly-Clark Corporation, a corporation of Delaware Application March 4, 1954, SerialNo. 414,170

3 Claims. (21. 137-92 This invention relates to stock consistency regulation for papermaking machines, and has to do with a method or apparatus for automatically controlling the percentage of papermaking substances contained in stock used for making paper.

In the manufacture of paper, the components of the furnish or papermaking stock, for example fibers of various kinds, fillers such as clays, and other substances, are usually mixed or treated in a beater. After the heating treatment, the stock may be subjected to other treatments before it is delivered to the flow box or other means by which the papermaking stock in its final form is deposited on the wire or screen of the papermaking machine. In general, it is found advantageous to beat or work the stock inititally at high consistency, for example at a solid content of up to 7 percent of the stock. Generally, the stock is then diluted to a consistency of 3 to percent in the stock chest, and the diluted stock at a predetermined rate of flow is then further diluted with white water and delivered to the paper machine.

It is quite obvious that if the desired consistency or solids content of the stock from the stock chest is supposed to be 4 percent, a lowering or raising of the amount of solid content in the stock to the extent of .1 percent, expressed as a percentage of the total weight of the stock, can be translated into a variation of 2 /2 percent, expressed as a percentage of the amount of the contained solids.

Although other operating factors have an effect upon the basis weight of the finished paper per unit of area, I believe that the principal cause of undesirable fluctuations in the basis weight is the variation in the stock consistency.

Much work has been done in developing automatic methods or arrangements for diluting the stock in order that it may reach the paper machine at the desired optimum consistenc but, so far as I am advised, it has been difficult, using the best obtainable apparatus, operated with the utmost skill and under the best conditions, to carry on continuous commercial operation in which the consistency is held within the desired range, particularly in cases where the papermaking operation requires a stock of relatively low consistency.

It is the purpose of this invention to provide a simple, economical, and practical, method or apparatus, the use of which will insure the maintenance of stock consistency within a much closer limit or range than has heretofore been feasible under like operating conditions.

To obtain this desirable objective, I utilize the wellknown principle that a suspension of solid material in a liquid vehicle has different flow characteristics than a similar liquid which does not carry any solid material in suspension, and specifically the principle that the frictional effect or loss of head due to the flow of an aqueous suspension of papermaking solids through a pipe of substantial length and of limited capacity, is greater than in the case of similar stock containing aflower percentage of like solid material.

Fatented Dec. 10, 1957 The apparatus disclosed in U. S. patent to Edward J. Trimbey, No. 1,178,193, issued April 4, 1916, is designed to operate upon this same general principle, and has been used with some measure of success under conditions where the requirements are not too exact.

In the operation of the apparatus disclosed in the aforesaid patent, it has been assumed that the variation in the loss of head by reason of the variation in consistency of the stock flowing through the impedance tube is the only factor which need be considered in view of the further assumption that the rate of flow to and through the impedance tube does not vary. On the other hand, I have discovered that not only is there a significant difference in the rate of flow of the stock to and through the impedance tube, but that this difference in the rate of flow has an important effect upon the efficiency of the apparatus.

Before making this discovery, great difficulties were encountered in the determination of precisely what were the causes for the undesirable fluctuations in the ream-weight of paper coming from the paper machine, in view of the fact that many other factors, for example variations in the speed of the machine and variations in the supply and distribution of stock to the wire, are other important factors. However, after an extended series of commercial runs on paper machines, I discovered that regardless of all other contributing factors, variations in the reamweight of the finished paper could generally be charged to variations in the consistency, i. e. the percentage of papermaking substance contained in the paper stock flowing to the paper machines. After further investigation and study I discovered that the variation in the stock consistency was due to a hitherto unrecognized variation in'the rate of flow of the stock sample to and through the impedance tube of the regulating apparatus.

The objectives of my invention, as above set forth, are realized by the use of the method and apparatus set forth in the following description and the accompanying drawings.

In these drawings:

Fig. l is a somewhat schematic view of the apparatus,

Fig. 2 is an enlarged elevation, partly in section, illustrating the principal parts of the regulating apparatus,

Fig. 3 is a section taken on the line 3-3 of Fig. 2,

Fig. 4 is a section taken on the line 44 of Fig. 3, and

Fig. 5 is a plan view partly in section taken on the line 55 of Fig. 2.

Referring to Fig. 1 of the drawings, the numeral 11 represents diagrammatically the beater or other stockworking machine which readies the furnish for delivery to the stock chest 12. The stock in this chest is normally at a higher consistency (i. e. it contains a greater percentage of papermaking substance) than is desired for supply to the machine chest of the paper machine, and ordinarily must be diluted to a lower standard consistency. The stock, after beating, may have a consistency as high as 7 percent, in which case it is customary to dilute to a consistency as low as 3 percent in the stock chest 12 before it is delivered into the machine chest. It is customary to make a further dilution of a predetermined volume of the standardized stock with white water before it is delivered to the head box of the paper machine.

From the stock chest the main flow of stock passes through a pipe 13 to a pump 14 from which a pipe 15 delivers it to the machine chest 16. Located in the pipe 15 there is a T 16a which permits a certain portion of the main flow of stock from pump 14 to be bled off through a sampling line or bypass 17 which extends upwardly, and terminates in an inverted U-tube, the top bend 18 of which is preferably located at a height of several feet above the regulating mechanism which will be later de scribed. The lower end of this U-tube 18 is open and discharges directly into the stock chest. A branch line 19 connected to the bleed pipe 17 diverts a portion of the flow from pipe 17 .into the lower end 20 of a pump well or vat 21 in which the stock is kept at a substantially constant level, the overflow passing off through a line 22 which also discharges into the stock chest 12.

From the pump well 21 a metering pump 23 delivers a sample of the stock at a uniform rate of flow through a pipe 24 and into the float chamber 25. Said float chamber 25 has a float 26 connected by means of a float rod 27 to a mechanism for actuating a valve, indicated at 28, for controlling the flow of a supply of liquid of consistency differing from that of themain flow so that when combined with the main flow of stock through pipe 13 the combined flow leaving the pump 14 will have reached the proper consistency. This controlled flow which is supplied through pipe 29 by suitable pressure is delivered through pipe 30 to the pipe 13 ahead of the pump 14 so that the two flows, one from the stock chest, and one from the pipe 29, are combined and passed through the pump 14 before the sample is taken out through the pipe 17.

Although it is possible in some cases to adjust or regulate the rate of flow of stock having a higher consistency than is desired in the combined flow, it is usually more convenient to control the flow of an aqueousmedium of a relatively low consistency. Hence, the pipe 29 is usually supplied with fresh water or with white water from the paper machine.

The depth of the sample of stock in the float chamber 25 is maintained at a substantially constant level by reason of the fact that the flow of stock from the float chamber is limited by the amount which can flow out through the impedance tube 31 at the lower end thereof. The impedance tube discharges freely into an open-sided box or housing 32, the lower end of which is connected to the'upper end of a pipe 33 which also discharges into the stock chest 12.

Referring to Figs. 2 to 5, inclusive, for a detailed description of the regulating mechanism, it will be observed that the sampling flow 19 enters the pump well 21 and is maintained in the well at a suitable operating level by means of an adjustable gate 34, the upper edge of which constitutes a weir or spill-way for disposing of surplus stock. Such adjustment of gate 34 may be effected by one or more screws 35 the lower ends of which are journalled in brackets 36 fastened to the gate 34. The upper ends of the said screws have threaded engagement with fixed nuts 37. By means of this arrangement the gate 34 can be raised and lowered to suit the particular requirements of the metering pump 23. that the flow from pipe 19 is always more than sufficient to supply the amount metered by the pump 23.

Although other types of metering pumps may be employed, I prefer to use a pump of the radial vane type operating in a cylindrical housing as shown best in Fig. 2 and Fig. 3. I have obtained good results by employing an arrangement in which there are three sections 38, 39 and 40 side by side, each having eight vanes 41, the vanes being staggered as shown in Figs. 3 and 4 in order to obtain a substantially uniform flow of stock into the discharge spout 24. The rotary portion of this metering pump 23 is housed in a closely fitting cylindrical casing 42 having an opening 43 for receiving the stock. The axis of the rotor and casing 42 is substantially below the level-44 of the stock in the pump well 21 so that no air will be trapped in the compartments of the rotor.

The rotor is keyed to a shaft 45 which is connected by means of a coupling 46 to another shaft 47 which through a suitable speed reducing arrangement is driven at a It will be understood few R. P. M., for example 1 to 10 R. P. M., by an electric motor 48 preferably of the direct current type, which is operated at any uniform speed selected within the speed range mentioned. The particular speed desired is selected by means of a suitable speed selector of any desired type as indicated at 49. It will be understood that by means of the arrangement described, I am enabled to deliver a sample'of stock down the spout 24 and into the float chamber 25 at a fixed flow rate which does not depend upon the consistency or viscosity of the stock, nor is such flow rate affected by variations in the flow of surplus stock over the weir 34.

As shown best in Figs. 2 and 5, the spout 24 discharges through an opening 50 in the wall of the cylindrical float chamber 25. This float chamber is provided with a partition 55 extending diametrically and vertically within the float chamber and down below the normal level 51 of the stock sample in the float chamber a sufficient distance to prevent pulsations or splashing of the stock in that part of the float chamber in which the float 26 is located. The lower end of the'float chamber 25 is constricted to form a neck 52 in the form of an elbow, the delivery end of which extends in a horizontal direction and is provided with a flange 53 to which is secured the flange 54 on the intake end of the impedance tube 31. The impedance tube 31 is made with a bend and extends back a sufficient distance to enter the open end of the rectangular funnel 32, the lower end of which is open and connects with the pipe 33, leading the sample back to the stock chest.

It will be understood that the length and diameter of the impedance tube 31'are so related in reference to the rate of flow from the metering pump 23 that the level 51 of the stock in the float chamber is such as to insure proper operation of the float and the regulating mechanism which the float controls. In the apparatus herein described there are two ways in which the float level can be adjusted. One way is'to raise or lower the discharge end of the impedance tube 31 as indicated in Fig. 2. This is made possible by rotating flange 54 on flange 53 as indicatedat 56 and 57 in Fig. 2. Another method of adjustment is to effect a change in the flow rate from the metering pump 23 by means of the speed selecting mechanism 49 above described.

The control of the flow of consistency adjusting fluid through pipe 30 is accomplished by mechanism similar to that disclosed in the Trimbey Patent No. 1,178,193 heretofore referred to, and which can be generally described as follows.

The float 26 is fastened to the lower end of the float rod 27 the=upper end of which extends upwardly through the arm of a rocker 59 pivoted on a shaft 60. On the upper end of the rod 27 is a fixed collar 61 bearing upon the upper face of the arm 58 so that the float and rod as a Whole'will be suspended from the arm 58 of the rocker member. This rock member has an intermediate upstanding arm '62 which by means of a compression spring 63 interposed between the arm 62 and a fixed abutment 64 serves to force the rock member 59 in a direction to counteract the weight of the float.

The numeral 65 represents a small motor which, by means of a worm 66 and worm gear 67, drives a horizontal shaft 68 at a relatively low rotational speed. The slow speed shaft 68 is equipped with a crank 69 which drives a pitm'an 70, the lower end of which pitman is pivoted at 71 to a positioning link 72, the other end of which is pivoted on a fixed pin 73. The pin 71 also serves as a pivot for the bifurcated member 74 so that the fork 74 partakes of the reciprocatory up and down motion of the pin 71.

The depending lower arms of the forked member 74 are equipped with oppositely facing dog members which are spaced apart a suflicient distance so as to accommodate in the space between them a reversible two-directional two-faced ratchet wheel 75 which isthreaded upon a valve-actuating stem 76. The ratchet wheel is prevented from movement along its axis by the fact that it is positioned between spaced abutments on the frame member 77. The valve stem 76 is non-rotatable, but is capable of longitudinal movement to adjust the valve 80.

The position of the fork 74 in relation to the ratchet wheel 75 is determined by the position of a control rod 78, one end of which is pivoted to the reciprocating fork 74 and the other end of which is pivoted to another arm 79 on the rocking member 59. When the rock member 59 is in a certain intermediate position, the up and down reciprocatory movement of the fork 74 will result in no rotation of the ratchet wheel 75 in either direction because neither of the dogs carried by the fork 74 will engage the ratchet wheel. However, if the level of the liquid in the float chamber rises due to an increase in the consistency of the stock flowing through the impedance tube 31, the float 26 will also rise and the spring 63 will cause the rock member 59 to be moved so as to draw the fork 74 to the left causing the right-hand dog on the fork to engage the right-hand face of the ratchet wheel and effect rotation of the same on the threaded valve rod 76. This will cause the valve rod 76 to be moved longitudinally in a direction to increase the opening of valve 80 and will result in a greater flow of dilution fluid through pipe 30 and into the main stock flow ahead of pump 14, thus effecting an increased dilution of the stock. In due course, this dilution of the stock will progress to a point where the dilution of the sample is suflicicnt to effect an increased flow of stock through the impedance tube 31, and the stock will flow through the impedance tube at a higher rate, resulting in a dropping of the level of liquid in the float chamber 25. This will cause the float 26 to be lowered, which downward movement of the float 26 will be translated into a movement of the fork 74 to the right, thus disengaging the right-hand dog of the fork.

On the other hand, if the amount of dilution water or other fluid being added to the stock through pipe 30 is so great that the consistency is reduced to below standard, the level of stock in the float chamber will drop and the rock member 59 will be moved in such a direction as to cause the valve 76 to be moved into a more closed position causing a decreased dilution of the stock until equilibrium has again been established. Due to the fact that the opening or closing of the dilution regulating valve 80 to the required extent is not instantaneously effected by an operative movement of the float 26, but is the result of a series of step by step movements each requiring a complete revolution of the relatively slow speed shaft 68, it will be understood that in order to enable the regulating apparatus to quickly correct variations in stock consistency while at the same time preventing hunting, it is important to reduce to a minimum the length of the sampling line and the volume of stock contained in that part of the apparatus which is between the T 16a and the impedance tube 31.

In order to obtain optimum results at different consistencies, it may be necessary in some cases to make some experiments in respect of various adjustments which should be made. For example, it may be found advisable to use a somewhat smaller or longer impedance tube, or a longer and smaller impedance tube, where relatively low consistencies are desired, or it may be advisable to select a difierent flow rate as has been heretofore described. Owing to widely varying conditions, the precise figures or amounts cannot be expressed in a formula, but by reference to the figures obtained by the following examples, no difliculty should be experienced in obtaining the desired results.

, Example Example Example Condition No. 1 No. 2 o. 3

Stock chest consistency (approx1mate). 3. 0 3. 5 5. 0 Machine chest consistency 2. 0 3. 0 4. 0 Gallons per minute of sample in combined flow by-pass Gallons per minute to metering pump well- 75 70 70 Gallons per minute through metering pump 60 5O 50 Approximate height of float level above discharge of impedance tube -i:uches 6 8 9 Inside diameter of impedance tube inches 3 3 4 Overall length of impedance tube inches.- 30 30 30 I claim:

1. Apparatus for regulating the percentage of papermaking substance suspended in a flow of aqueous papermaking stock, which comprises means for combining two aqueous flows containing different percentages of papermaking substance, a valve adapted to adjust the ratio of said two flows, a main pump for delivering the combined flow to a paper machine chest through a main flow pipe, 21 bleed line from said main flow pipe for continuously Withdrawing a sample of stock from said combined flow and delivering said sample to a pump well, a second pump of the constant displacement type for withdrawing a predetermined quantity of said sample from said pump well, means for driving said second pump at a selected constant speed, a chamber arranged to receive the sample withdrawn by said second pump and having an outlet pipe for discharging said withdrawn stock, said outlet pipe being of such length and capacity that the flow of stock out of said chamber will be impeded, thereby forming a pond of stock in said chamber of a depth varying in accordance with variations in the percentage of substance in said stock, and a float in said pond for operating said valve whereby at a given pump speed the percentage of substance in the combined flow will be maintained constant.

2. Apparatus for regulating the percentage of papermaking substance suspended in a continuous flow of aqueous papermaking stock, which comprises means for continuously combining two aqueous flows containing different percentages of papermaking substance, a valve adapted to adjust the ratio of said two flows, a main pump for delivering the combined flow to a paper machine chest through a main flow pipe, a bleed line from said main flow pipe for continuously withdrawing a sample of stock from said combined flow and delivering said sample to a pump well, said pump well having an outlet for the discharge of surplus of the sample whereby an approximately constant depth of stock is maintained in said pump well, a second pump of the constant displacement type for continuously withdrawing stock from said pump-well at a rate less than the amount received by the pump well, means for driving said second pump at a selected constant speed, a chamber arranged to receive the stock withdrawn by said second pump and having an outlet pipe for discharging said withdrawn stock, said outlet pipe being of such length and capacity that the flow of stock out of said chamber will be impeded, thereby forming a pond of stock in said chamber, and .a float in said pond for operating said valve.

3. Apparatus for automatically regulating the percentage of papermaking substance suspended in a continuous flow of aqueous papermaking stock, which comprises means for continuously combining two aqueous flows containing different percentages of papermaking substance, a main pump for delivering the combined flow to a paper machine chest through a main flow pipe, a bleed line from said main flow pipe for continuously withdrawing a sample of stock from said combined flow and delivering said sample to a pump well, said pump well having an outlet for the discharge of surplus stock whereby an approximately constant depth of stock is maintained in said pump well, a second pump of the constant displacer'nent type for continuously withdrawing stock from said pump well at a rateless than the amount received by the pump well, means for driving said second pump at a selected constant speed, a chamber arranged to receive the sample withdrawn by said second pump and having an outlet pipe for discharging said withdrawn stock, said outlet pipe being of such length and capacity that'the flow of stock out of said chamber will be impeded, thereby forming a pond of stock in said chamber, a float in said pond for changing the ratio of the uncombined flows, and manually controlled means for changing the selected speed of the second pump so as to change thedepth of said pond and thereby-change the desired percentage of substance in the combined flow.

References Cited in the file of this patent UNITED STATES PATENTS 1,178,193 Trimbey Apr. 4, 1916 2,392,026 Cram Ian. 1, 1946 FOREIGN PATENTS 134,852 Austria Oct. 10, 1933 899,525 France Aug. 14, 1944

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