US2615329A - Paper stock analyzer - Google Patents

Description

Oct. 28, 1952 G.. s, wlTHAM PAPER STOCK ANALYZER 2 SHEETS-SHEET l Filed July 16, 1946 TO MACHINE CHEST OR MIXING PUMP INVEN TOR.

FROM JORDAN Oct. 28, 1952 G. s vwlTHAM 2,615,329

' y PAPER STOCK ANALYZER Filed July `16, 1946 2. Simms- SHEET 2 F-IG.3

WHITE WATER AIR HEAD BO TO MA INE CHEST y OR MIXING PUMP INVENTOR.

Patented Oct. 28, 1952 PAPER STOCK ANALYZER George S. Witham, Hudson Falls, N. Y., assignor to The Bristol Company, Waterbury, Conn., a corporation of Connecticut Application July 1e, 194s, serial No. 683,969

This invention relates to devices for analyzing paper stock, and more especially to instrumentalities for providing Va continuous record of interrelated physical' characteristics of paper stock during the process of manufacture, whereby regulation and controlof these characteristics may be effected with,` a minimum departure from optimum conditionsv in the paper, machines.

Two important, and interrelated, though distinct, factors in the quality of the stock fed to paper machines are freeness,4 and consistency. The first of vthese terms is based primarily on the coarseness of the suspended fibres. Free stock is that which consists of coarse fibres. Slow stock consistsv in general of fine fibres with frayed ends, and may contain a greater or less proportion of one 'or more of a variety of organic or inorganic fillers,' which impart various desirable properties to the finished paper. A characteristic of slow stock is that it tends to form a dense mat from which vwater drains slowly. The degree of freeness ofI stock may therefore be determined by the rate of drainage of water from it; but in order that there be a vstandard of reference, it is essential that lother'v'ariable factors be eliminated, or else incorporated in a suitable compensation. The principal variable to take into account before attempting to determine freeness is that of consistency. These two magnitudes are closely associated, and may readily be confused. In fact, they may at times be measured by identical means, thev only distinction lying in the range of measurement for which the apparatus vis set. Consistency, however, is synonymous with viscosity, and affects the manu-v facture of paper in quite' a different manner from the influence of freeness. Control of consistency is brought about by regulation of the amount of water in the stock, which may generally be effected automatically, while control of freeness requires adjustment of the jordan plug or beater knives, as the case may be, which is generally better done by manual means subject to the observed freeness values.

It is an object of the present invention to provide means whereby simultaneous determination of consistency and freeness on flowing paper stock may be coordinated in a manner to eliminate in the former such variations as might otherwise detract from accuracy of measurement of the latter.

It is a further object tojprovide means whereby freeness of a selected specimen of paper stock may be determined with an accuracy and precision not heretofore characterizing the art,

s claims. (o1. vs -es) It is a further object to provide means ofthe above nature which shall be compact and substantially unitary in construction; and readily adaptable to existing installations of paper manufacturing apparatus.

In carrying out the purposes of the invention, it is proposed to provide, integrated in a common unit, a consistency measuring and controlling instrument, and an improved form of freeness determining apparatus and so to coordinate their performances as to utilize each with maximum efciency.

In my former Patent No. 1,945,988, granted vFebruary 6, 1934, and reissued as No. 19,997, J unel 2, 1936, I have pointed out that freeness may be effectively determined by maintaining a paper vstock at a uniform consistency, establishing a 'filter mat of material from said stock While maintaining balanced'atmospheric pressures on opposite Sides thereof, and performing a quantitative measurement on the liquid whichv drains through said stock. As set forth in said patent and reissue, the forming of said mat is accomplished by the use of a foraminous drum immersed toa predetermined depth in the stock Whose characteristics are being determined, and caused to rctate therein to gather on its outside surface a quantity of material rfrom said stock in the form of a mat, from which water may drain into the interior'of the drum, and subsequently flow therefrom at a measured rate,l rIn the application of this principle, I have found that the formation of a mat of uniform thickness may be effected with a greater degree of uniformity if the stock be allowed to ow on to the upper surface of the rotating drum at a suitably regulated rate and be carried along with the motion of the drum, over its topmost level, draining meanwhile through the perforations in said drum into a suitable interiorly positioned receptacle, and subsequently dropping off the drum as the extremity of its horizontal diameter is approached.

In carrying out the purposes of rthe present invention, it is proposed to provide a stockanalyzing unit involving a box assembly through which passes the whole volume of stock beingy supplied to a paper machine, there being continuously diverted from said stock a representa-` tive and measured sample which 1by means of a suitable trough is delivered to the Vupper exterior surface of a rotating. foraminous drum, the drainage through which, being continuously measured, provides a basis for determination of freeness of the stock.v It is furtherproposed to include in said assembly a device for measuring the consistency of the stock and regulating the same to a predetermined value, whereby to maintain said consistency not only at an optimum value for the process in hand but also at such a predetermined value as to impart quantitative significance to the freeness measurement obtained on the rotating drum.

' In the drawings: Fig. 1 is a top elevation of a. stock analyzer embodying the principles of the invention.

Fig. 2 is a. side elevation of the same, shown partly in section, as on the line A-A in Fig. 1.

Fig. 3 is a sectional view of an importantelement of the invention.

Fig. 4 is a diagrammatic representation of an installation of a stock analyzer incorporating the principles of the invention.

Referring now to the drawings:

The numeral Ill designates an assembly including a box portion and a platform portion I2 integrally mounted uponfsuit'able supporting legs I3,Y whereby the same may be maintained a convenient distance above the floor upon which it rests. The box portion II is provided with a lateral opening I4 adapted for connection to a pipe or conduitI I5 through which stock to be tested is admitted to said box. In the bottom portion of said box is a rectangular opening IB communicating by means of a tapered chute or connection I7 with a pipe or conduit I8, whereby stock may be dischargedv from the apparatus. Positioned within the box II, on the side toward the inlet opening I4, but displaced therefrom, are two bales 20 and 2|. The baille 2U which is the closer to the inletY I4 extendsv substantially to the top of the box II, and has a xed opening in its bottom portion. The baille 2| is formed at its upper edge into a weir of considerably lower level than the top of the baille 20, and at its lower portion has an opening 22 whose area may be adjustably varied by means of a gate 23 vertically adjustable with respect to the baille 2| and movable by means of a rod or screw 24,'whereby said gate may beV raised or. lowered, as required. Between the baille 2| and the wall of the box II remote from the 4inlet I4 the box is open at the top and adapted to contain. elements presently to be described. Along the'edge of the opening I6, and on the side thereof toward the baille 2| is a low weir 25, over which the stock, having reached the top thereof, may flow into said opening and be discharged through the chute I1 into the conduit I8.

Mounted upon the platform portion I2 is a box element 2`| having its interior in free communication with the main box portion II, and with its inside bottom surface sloping unobstructedly toward the opening IB in the bottom thereof. Journalled for rotation about a horizontal axis in the box portion 27 is a drum member 28, whose construction will be more clearlyA understood by reference to Fig. 3. The essential part of the drum 28 comprises a cylindrical shell 29 formed of formaminous material, such as perforated sheet brass, bronze or stainless steel, having radially extended flange portions 30 of greater diameter than said cylindrical shell. One of said flanges is of discoid conformation, extending to the center of the drum, and having a hubportion 3| 'whereby said flange and the whole drum structure is carried as a cantilever from a rotatable shaft 32. vOn the inner surface of the cylindrical portion, and serving as supports for the foraminous shell 23 is a series of uniformly spaced radially disposed fins 33, inwardly directed toward the axis of the drum. The shaft 32 is directly attached to a speed reducing mechanism 35 adapted to be driven by an electric motor 36, so that the drum will be caused to rotate at constant velocity in the direction indicated by the arrow in Figs. 2 and 3.

A sloped ltrough 31,-preferably ,of rectangular section and open at the top, extends vfrom an opening 38 in the baille 2|, a short distance below its upper edge, across the open space in the box between said baille and the wall which is remote from the inlet I4, passing through said wall and terminating in a portion positioned between-the flanges of the rotatable drum 29, having a minimum of clearance therefrom, to provide Aa substantially water-tight joint therewith, 'and terminatingV in close proximity to the foraminous surface of the cylindrical shell 29 and on a line intermediate the extremities of the horizontal and vertical diameters of said shell, on the rising sidefthereof. The slope of the trough 3l where it crosses the open part of the rbox VI is madesuch that, as Athe stock is extruded through the opening 38, and flows by gravity along Vthe troughfsome of said stock will tend to overflow Vthe edges vof .the trough, spilling into the box beneath, leaving a stream of substantially the section of the trough to pass ythrough vthe opening in the wallof the box,V and flow along the portion ofthe trough which is ljuxtaposed to the drum 28. Said last-named portion-of the troughl `3"|. is made preferably o f i a slightly steeper slope than the'flr'st-named portion.l so that, with theresulting increasedspeed of passage therethrough, `the levelof the stock will be lowered suiciently vthatv there will be no vfurther spilling over the edges,fand the stock will be delivered to thesurface of the drum ata substantially constantvolume per unit time.

While the troughhas been hereinbefore stated as terminating at the periphery of the foraminous shell 29 on a line intermediate the extremities of the horizontal and vertical diameters of said shell, the-exact location of the end of the trough is a matter of design, and would be determined partially by experiment, and with consideration of the velocity at which the drum would be operated. In general, the arrangement will be such that, as indicated in Fig. 3, the stock deposited on the shell would be drawn away from the trough in an unbroken mat, without any tendency ofthe material to pile up at the outlet of the trough or to separate as it passes over the upper surface of the shell.

Internally ofthe drum, and slightly below the horizontal vdiameter thereof, is fixed an open trough 4U, extending across the drum but clearing the inner ends of the radial ns 33. The trough 4I) is connected by meansof a suitable drainage pipe 4I, shown in Figs. 1 and 2, whereby water falling from the inner surface of the drum into the said trough will be collected and drained therefrom. I'he drainage pipe 4I passes into a vertically disposed cylindrical receptacle l2 having in its lower portion a discharge pipe d3 of xed opening. A spray pipe 44 terminating in a radially perforated section positioned within the drum 28 below the trough 4B, is adapted to be supplied with water under pressure from an external source, whereby to direct upon the inside of the drum a continuous, and substantially horizontal, spray of water to wash the foraminous surface clear of all accumulation 0f paper stock. f

The consistency measuring and controlling device, for which, per se, no invention is herein claimedcomprises a vertically disposedmfCylindrical vessel 45 having midway of its sidejfa T connection 46 attached to the baille 2|, and communicating with the space to the rear thereof through a suitable opening adjacent to, and at approximately the same level as, the opening 38, whereby said vessel will be supported within the open portion of the box I I, and will receive from the stock-filled space to the rear of the baffle a continuous supply of said stock identical in all characteristics with that passing through the opening 38 and the trough 31 to the drum 28. To the lower portion of the vessel 45 is attached a projecting pipe 41 of smaller section area than said vessel, and preferably made angularly adjustable about a horizontal axis so that its outlet may be positioned at any desired level with respect .to said vessel. Suitable adjustment may be effected by means of a vertical rod 48, hinged to the swingable portion of the projecting pipe 41, and at its upper extremity threadedly engaginglocking thumb nuts 49 bearing upon a bracket 50 xed to a stationary part of the box II. There is thus provided an outlet from said cylindrical vessel characterized by a constricted conformation whereby, with a constant rate of inflow, the level of material within said vessel will vary according to its viscosity or'` consistency.

In order to provide means for expediently determining the levels of liquid, or semi-liquid masses in various parts of the apparatus described, which levels are functions of the several variables which it is desired to measure, there are provided bubbling tubes of conventional type, these being clearly indicated in Fig. 2;; A bubbling tube 5I vertically extended into the receptacle 42, terminating near the bottom thereof, provides means for determining the level of water which may accumulate in said receptacle. A bubbling tube 52 extends into the open portion of the box II, near the Weir 25, ywhereby may be determined the depth, and hence the volume, of material passing over said weir,l through the opening I6, and into the chute l1, to be discharged through the conduit I8. A--bubbling tube 53 is vertically extended into thecylifndrical vessel 45, terminating some distance below the T 46, whereby may be determined `the level of stock within said vessel.

In Fig. 4, is shown diagrammatically the arrangement of an installation wherebythe invention may be applied to analysis of paper stock. A Jordan engine 55 is adapted to receive a supply of paper stock from a head-box 56 through an adjustable gate 51. The connections associated with said head-box may be of anyone of a number of arrangements well known inthe art, and forming no essential part of the present invention. part of a beater pump chest 58, circulated by means of a pump 59 may enter said head box through a conduit 60, the stock level within said box being more or less regulatedby partitions 6I and 62 over the top of which a flow of said stock may take place. Over partition 6I the stock flows into a compartment communicating with the gate 51, and thence to the Jordan engine, while surplus stock flows over the top of partition 62 into a compartment, whence, by means of a conduit 63, it is returned to the dump chest. A dilution pipe 68 having therein a pneumatically actuated regulating valve 69, and connected preferably between the beater For example, stock from the lowerl .s chest outlet and the intake side of the pump 59 provides for a controlled Supply ofv white water to the stock, whereby the consistency of the latter may be effectively regulated.

The bubbling tubes 5I, 52, and 53 are supplied with air from a source 10 through suitable flow regulators or valves 1I, 12, 13, respectively. The bubbling tube 5I is connected by meansy of a conduit 15 to a pressure recorder 16, whereby may be obtained a measure of the depth of liquid in the receptacle 42. The bubbling tube 52 is connected by means of a conduit 11 to a recorder 18, whereby may be obtained a measure representative of the volume of stock passing through .the analyzer. The bubbling tube 53 is connected by means of a conduit 19 to a combined recording and controlling instrument 80, whereby may be obtained a measure of the depth of stock within the vessel 45, which measure may also be utilized in a pneumatic device of conventional form to control the supply of compressed air from the source 1I) to a conduit 8|, communicating with the operating element of the valve 69, thereby to regulate the rate of admission of white water to the stock in the head box 56.

Operation of the apparatus embodying the principles of the invention is as follows: A continuous flow of stock from the Jordan engine 55 is delivered through the conduit I5 and the opening I4 into the box II, where the baille 20 acts to reduce its velocity of flow, allowing it to pile up back of said baille and establish a more or less variable head. The stock will then flow beneath the baille 20 into the space between the same and the baille 2|, Where it will rise to such a, height to flow over the upper edge of the latter baffle and spill into the open section of the box. The amount of stock flowing over the top of the baille 2I may be regulated by adjustment of the gate 23, whereby the area of the opening 22 is varied to an extent to by-pass a suitable volume of the stock and maintain the depth over the weir formed by the top of the baille 2I at a desired, and reasonably constant,'level. The greater portion of the stock entering the box II will thus pass either over or under the baille 2 I directly into the open part of the box II and thence over the Weir 25 and through the opening I6 and the chute I1, to be discharged through the conduit I8.

There being established a reasonably constant head above the opening 38 in the baffle 2|, there will flow therethrough' into the trough 31 a considerable portion of the stock, and the stream should be of such volumeas to overflow the edges of said trough, the surplus spilling into the open part of the box II, and the remainder passing on to the steeper part of the trough at a substantially constant rate of flow, whence it is delivered to the surface of the drum 28. As the stock delivered to the surface of said drum at a level be- ,low its uppermost point is carried upward by rotation of the drum, the water will drain through the foraminous surface of the shell 29 passing to the interior thereof, falling into the open trough 40. The inwardly projecting fins 33 will tend to prevent the water being carried downward along the inside surfacev of the shell, and will cause substantially the 'whole volume of water which passes through the openings therein to fall into the trough 40. As .the mass of stock is carried further from the trough and over the topmost portion of the drum, the loss of water therefrom will cause it to be Adeposited upon the outer surface in a mat of continiually decreasing thickness, untiLit hasbeenfcarried-to the-1 req-noteVVA ex, tremity.Y -of they horizontal' diameter of the- `shell. There is thusbeing continuously established-url der controlled conditionska mat ,or layer .of the stock, fromev which the water is allowedtodrain for, a predetermined time interval; and, sincethe rate of delivery-of material to the :surfaceof the drum is maintained constant, the amount of water collected in the trough Mlwill at alltimes be a measure of the freeness; of said stock, subject tothe maintenance of a constant consistency value. -v Y After the layer of material accumulated on the surface of the shell 29 passes the extremity of `the horizontal diameter thereof,it will tend-to become detached and drop into the box portion 21, flowing along the sloping bottom surface .thereof to rejoin the principal mass of `stock passingfinto' the chute I'I. The spray directed.` from thel pipe 44 against the interior of the shell 2S. Willgwash said shell clear of all accumulations of stock'or slime, and will leave the foraminoussurface clean and ready to receive a further deposit 'of stock as with rotation of the drum it rises to the position of thetrough 37. i;

As the outlet-43 from the receptacle 42 .iszmaintained constant, it follows that thelevel of water in said receptacle will vary `with the rate of drainage of water through the foraminous wall of th'e drum 28, and will therefore be a measure of the freeness of the stock carried over the drums-LAS; according lto well known principles, the backpressure of air in the tube as it'vis'I bubbled through the lwater in said receptacle; is proportional to the depth-thereof, it followsthat theindication or record obtained upon the, 'instrument '1.6 will be a measure of the freen'ess'fof the paper stockunder test, 4and may be directly `expressed in suitable units. y a .i .Y Becausefthe sample of stockdiverted into the vessel 45 for purposes of consistency determina'- tion is obtained at substantially the same location as the sample which passesthroughxthe opening into the trough 31 for freeness determie nation, and because ofthe homogeneous characteristic of the stock, assured by the distribution due to the baies and 2l, it .may be assumed that the -sample subjected to consistency -determination is in all respects identical to that .whos'e freeness is measured. Because the rate of out'- flow of stock from `the vessel 'through the extended and constricted pipe M-.will be dependent upon the consistency of said'stock; and' since ,the rate of admission is subject tov a substantially con-1 stant head, it follows that the level ofthe surface of the stock inthe vessel 45 will va'ry with' said consistency, said level rising as the stock'becomes more viscous and viceversa. Because-the back pressure of air in the tube 53 as it is bubbled through the stock in said vessel .Willube 'propere' tional to the depth thereof, it follows thatthe measurement obtained yby th'einstrument 8i!l will be representative'of the consistency of the stock; and may be directly expressed. in 'suitable units.y l

.The control mechanism-fin the instrument '8D' being made subject to the measurement obtained. upon said instrument, may' be caused to vary the pressure of air applied Athrough vthe vcon'duit'iil` to the regulating valve 69,1.iand thus control the rateof admission 'of whitewater torthe 'stock aboutgto be delivered to the Jordan. In thi'sway, variations1 in consistency of the stock under anal'- ysis will be immediately detected; andrectifled ina minimum of time from the occur-renc'eof anychange. l. l

. .1 y.As vthe amount. of stock which diverted into the trough 3 1- for the lpurpose-of freeness determinationvwill generally be a negligible proportion of the wholesupply of stock passing through the box. i I., the volume of material passing over the weir- 25 into.v the outlet I6 lmay be taken as representative ofthe total amount of s tock received from the Jordan and later delivered to the paper machines.` Since the back pressure inthe bubbling tubej-,52 `will be a measure of the depth of stock flowing over the weir 25, the instrument i8 connected to said bubbling tube may be calibrated in terms of rate-of-ow of stock'through the analyzer; and, if desired, said instrument may be equipped with anyV one of avnumber of well known forms of integrator, whereby the total volume gof stock handled by the analyzer in rany given time may be accurately determined; The `terms and expressions which I have employed are used as terms of description and not of limitation, and jI-have no intention, in the use of suchterinsand expressions, of 'excluding any equivalentsof the Afeatures shown and "described Ln-portionsv thereof, but recognize ythat various modifications are possible .within the scope of the invention claimed.-y

I claim: f .1; In a` device for determining the freeness of a semi-fluid stock containing .suspended brous material, the combination of a. drum having a horizontal axis and axially displaced radially extendingfianges with a foraminous cylindrical surface therebetween, said flanges extending outwardly beyond said surface, said dru'rn being open to atmospheric pressure both above and below said foraminous surface to expose opposite sides of lsaid surface to said pressure,- means for rotating said drum at a substantially constant velocity aboutsaid axis, means comprising a compartment for' maintaining a supply of said stock under a predetermined head, Vsaid compartment having an opening in a wall thereof at a predetermined distance-.below the top of said wall, a trough communicating at one end with said opening, said trough extending downwardly-from said opening and terminating at its lower end between said nanges fordelivering 'stock fromv said compartment to said foramino-us surfaceof said drum on the ascending side of the latter, said trough having a section adjacent saidopening of such slope that stock emerging fromfsaid opening under a predetermined head spills overthe side edges of said trough, said trough also having a section of steeper slope adjacent said foraminous surface of said'drum, andmeans for continuously/,determining the rate of drainagerof Water from said stockthrough a predetermined circumferential portion of said foraminous surface.

' 2, n a device for determining the freeness of a semi-fluid stock containing suspended fibrous n material, `the combination of a drum having a horizontal Aaxis and axially displaced. radially extending flanges with afora'minous cylindrical surface therebetween, said flangesextending out wardly beyond said surface, saiddrum being open to` atmospheric pressure both above 'and below said foraminous surface to expose opposite sides of 'said surface to said pressure, means for rotating' said drum at a substantially constant velocity about' said axis, vmeans comprising an inclined trough having an end 'positioned between said flanges for delivering a continuous stream of stock to the exterior surface of said drum on the ascending side to fiow over the top thereonmeans comprising a-compartment having' an opening in a wall thereof for continuously` supplyingy stock to said trough under a substantially constanty head, said troughv having asteeper slope adjacent said foraminous surface than adjacent saidfopening, and means for continuously determining the Vrate of drainage of Water from said stock through a predetermined circumferential portion of said foraminous surface.

3. In a device for determining the freeness of l a semi-fluid stock containing suspended fibrous in said receiving means for determining the rate of drainage of water from said stock.

material, the combinationof a cylindrical;` drum I rotatable about a horizontal axis andhaving a foraminous surface normally exposed on yboth sidesy to atmospheric pressure, said drum having at opposite ends radially extending iianges projecting outwardly beyond said surface, a conduit having anv end positioned between said "flanges for delivering tothe exterior surface ofv said drum on the ascending side thereof and abovega. horizontal plane containing said drum axis,"a conof said drum, means communicating with the interior of said drum forreceiving waterfdraining from said stock through said Ioramin'ous surface, and means responsive to the height o'iwater 2O tinuous stream of said stock to pass overthe top e GEORGE s.

REFERENCES CITED Thev following references are of record in the file of this Ipatent: v

Great Britain 1936

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