US2472324A

US2472324A - Apparatus for handling liquid suspensions

Info

Publication number: US2472324A
Application number: US529540A
Authority: US
Inventors: Dan B Wicker; Charles W Cox
Original assignee: American Viscose Corp
Current assignee: Akzo Nobel UK PLC
Priority date: 1944-04-04
Filing date: 1944-04-04
Publication date: 1949-06-07
Anticipated expiration: 1966-06-07

Description

June 7, 1949. D. B. WICKER ET AL APPARATUS FOR HANDLING LIQUID SUSPENSIONS Filed April 4, 1944 2 Sheets-Sheet 1 NVENTORS. @Q/u, 62

ATTORNEY June 7, 1949. D. B. WICKER ET AL v I APPARATUS FOR HANDLING L IQUI D SUSPE'NSIONS Filed April 4, 1944 2 SheetsSheet 2 v HgV/ENTORS.

. BY fi e WM ATTORNEY Patented June 7, 1949 APPARATUS FOR HANDL ING LIQUID SUSPENSIONS Dan B. Wicker, Dunbar, and Charles W. Cox, St.

Albans, W. Va., assignors Corporation, Wilmington,

Delaware to American Viscose Del., a corporation of Application April 4, 1944, Serial No. 529,540

1 Claim.

This invention relates to means for handling liquid suspensions of particulate materials, and more particularly to means for handling liquid suspensions of textile staple fibers.

In withdrawing liquids from suspensions of particulate materialsit is a common practice to apply vacuum beneath layers of the suspension distributed on the surface of a so-called vacuum table, the vacuum serving to draw the liquid downwardly from the material at a rapid rate. The vacuum table consists of a horizontally disposed circular table having a liquid-perviou annular deck provided with side walls, and being rotatably mounted above closed chambers which lead separately-to the ports of a circular valve through which vacuum is applied or liquid withdrawn. It is extremely difficult to deposit liquid suspensions of particulate materials on the rotating surface of the vacuum table in the form of a continuous blanket of uniform thickness and density throughout, due to the annular shape of the surface and the consequent difference in linear velocity between the inner and outer portions thereof. However, such uniformity is essential, especially when the particulate material comprises textile fibers, to insure that all of the fibers will be equally treated.

It is, therefore, an object of the present invention to provide a novel means for depositing a liquid suspension of textile staple fibers or the like on the annular liquid-pervious deck of a, conventional rotating vacuum table, either in the direction ofrotation of the table, or in reverse direction thereto, and, in any case, in the form of a blanket or layer of uniform thickness and density. It i another object of the invention to facilitate the continuous removal of a mass of textile fibers or the like from such a vacuum table after liquid has been withdrawn therefrom.

These and other objects are accomplished by providing a novel trough having a delivery lip or edge such that the material is deposited on each annular subdivision of the deck of the rotating vacuum table in an amount directly proportional to the relative linear velocity thereof.

- In the drawings,

, 2 Figure 7 illustrates a graphical method of designin an embodiment of the invention.

Referring more particularly to Figures 1 and 2,

the numeral 2 indicates a conventional vacuum' table having an inner annular periphery 3 :de-

fining a central portion d and an outer annular periphery 5, and mounted on a spindle or the like (not shown) for rotation in counterclockwise direction above a plurality of closed chambers Ill, which lead to a circular valve provided with suitable connections to vacuum lines and discharge receivers (not shown). The inner and outer annular peripheries of table '2 define the limits of a liquid-pervious deck 6 having a blanket or layer of a liquidsuspension of textile staple fibers I deposited thereon from trough 8 which is inclined at a slight angle with respect to table 2. Pipes 9 positioned above deck 6 are provided with a plurality of spray heads l2, from which the same or different liquids may be applied to the fibrous blanket on deck 6 at predetermined points during rotation of the table, if desired.

An endless belt l3 having spikes or prongs l4 thereon is positioned directly over deck 6 and is driven by pulleys l5 and It in the direction indicated by the arrows, so that the spikes or prongs l4 engage blanket I and lift it from deck 6 after table 2 has mad almost one complete rev-- olution. A dOffil'lg roll I! is provided with flaps Figure 1 is a plan view of a device according t the invention;

Figure 2 is an elevational sectional view of the device shown in Figure 1, one element thereof i8 which brush the fibers off belt l3 into chute I9 through which they are delivered to container 20.

A dofiing roll 21 having spikes 22 thereon may also be provided adjacent belt l3, to catch any fibers which may cling to deck 6, or which accidentally pass under belt l3, and to deliver such fibers to a point where they will be engaged by spikes I4 on belt I3 and removed to container 20. Trough 8 for depositing the liquid suspension in uniformly thick layers upon deck 6 of table 2 comprises two

side walls

23 and 24 and a plane bottom 25, as shown more clearly in Figure 2, and may be provided with cross-baffles 26 and 2'! (Fig. 2) to insure even distribution of the suspension across the entire width of the trough. Trough 8 is provided with a delivery lip or edge '28, the termini of which, regardless of the relative widths of trough 8 and deck 6, substantially coincide with the inner and outer peripheries of the deck, and which, when the trough is projected on the table, substantially defines an arc of a circle, so that when the liquid suspension flows through the trough at a fixed rate and table 2 is rotatedat a fixed rate, the portion of the flowing sheet of the liquid suspension which is deposited upon any particular narrow annular subdivision of the 3 deck is directly proportional to the relative linear velocity of that particular narrow annular subdivision. Thus the amount of the suspension deposited upon the inner portion of the rotating surface is less than the amount deposited on the outer portionthereof, so'that thelinear velocity differential between such rotating portions is compensated for, the weight of the suspension deposited per unit of annular surface is constant, and the blanket or layer of material laid upon the surface is continuous and of uniform thickness and density throughout.

The projection of the relivery lip oredge 28 of trough 8 on the table may be regardeduas defining substantially an arc ofranimaginary circle, the locus of the center of which lies at some point on the surface of the deck on a radial line through the center of the table 'ata rightangle to the longitudinal axis of the trough,'the distance of such locus from the center of the table being dependent upon the width of the trough, and the width of the particular annular surface to which the trough delivers. The distance of the locus of the center ofthetcircle which defines the trough lip, from: the center of the table, may be determined by dividing the difierence between the squares of the-greater and smaller radii of the table by twice the width. of the trough. .The gi'eater'radius of the table is measured from the center of the table to' theannular periphery'fi, and the'smaller radius-ismeasured from the center of the table to annular. periphery 3. From these relationships, the shape of the lip can be determined mathematically.

As seen more particularlyin Figures 3 to"? inclusive, the width of the trough may .be the same 'as that of the annular-deck, or it may be greater or less than thelatter. 'In all cases the projection of the termini of the .arcforming the lipupon the table substantially.coincides with the innerandtheouter periphery of the annular surface, and the projected arc is not greater than .a. semi-circle. Thus, for example, when trough 8 is of the same vwidthas annular deck 8, and is positioned so that its edgesaretangential to the peripheries.ofthedeckfi, the locusof the center of the imaginary-circleprojected from the lip lies on the Y axis atapoint.,midwaybetween the inner and outer peripheries 3'and 50f deck 6, and the arc is a semicircle,..as shown in Figure 3.

In Figure 4, the widthofitrough 8 is less than the width of annular declc fi-sand the trough is spaced away from the -X axisand positionedso that neither of its edges is tangential tothe peripheries of deck 6, In that. case, the locus vof the center of the imaginary circleiprojected from the lip lies on a radial line-extending at a right angle to the longitudinal axis of. the trough (Y axis) at a point close to the outer periphery of the deck, as shown at 30,-and the arc is less than a semi-circle.

In .the combinationillustrated in Figure. 5, the width of trough 8 is greater than-the-width of deck 6, and the troughis epositioned so that one ofits edges coincides with theX axis, and the other is tangential to the outer periphery of the deck. There, the .locus' of the center of .the imaginary circle projectedzfrom the lip lies on a radial line extending at a rightangle. to the longitudinal axis of the trough (Y axis) at a' point closev to the inner periphery of the deck, and the arc is less than a semi-circle.

Figure 6 illustrates a combination in which the width of trough 8 is the.- sameas that of. deck 6,

but the trough'iis positioned-so .that. neither .of-

:required 'lipzempirically, by a graphical procedure illustrated by the following discussion:

.In order to effectually deposit the material from trough 8 evenly and uniformly upon annular deckii, any portion of the trough, extending from, and having a-width W as measured from, that side of the trough which delivers to the annularportion of annular deck 6 nearest the .inner.=annular periphery 3 of table 2, should deliver to a portion of such deck defined by the inner periphery 3 and an imaginary concentric outer circle having a radius RtIlE-tedin accordance .with' the equation:

(Ra -R0 where R0 is the inside radius. ofthe annular deck-6; and

K is a factor which is determined for any given system by the inside andoutside radii 'of deck'fiand the overall channel width of troughB.

When the widthoftrough' 8' and the inside and outside radii of deckifi on tablej2'are' known; the numerical value of K may .be. found by substituting these known values in the above equation.

'Thenthe annular de'ck'may be 'divided into a series of annular portions by marking'oif'a series. of points each. spaced, at .any arbitrarily selected progressively greater distance from the center of the table andtintersectingeach of the series 'of points .so, marked ofi" with a circle. Then the value .of the radiusyof'the'outer circle defining each" portion .is substituted for Rt in the equation, and a valueof'W' is solved for each substitution. Then .ptheitrou'gh is divided into parallel, longitudinally extending strips between imaginary lines 'spaced;fromthat edge of the trough which extends to apoint above the inside periphery of the annular surfacedistances corresponding to the valuesof Wbbtained. The intersections of vertical planes through the; parallel imaginary lines with the imaginary concentriccircles determine lociwhich define the arc of the trough lip. ,A' scale drawingshowing the trough approaching the tableat the desired angle maybe prepared, showing the trough-widths as lines parallel to the sides of the trough, and the deck'widths as concentric circles, the intersection of eachparallel line with its-corresponding circle defining the projection of the delivery lip or edge 28 of each trough width'on the table As an-illustration, let it be'assumedthat a vacuum table Ihas adiameterof 12 feet, andthe central-portion thereof has a diameter-of 4 feet (Ro=2 feet) while the inside-width-of trough a is'-.3. -feet. 'In'that case,=.the' numericalivalueiof K is 10.67, .as determinedbyzssubstituting'z'the values of 6, 2, and 3 for Rt, Ro, andrwrespectively inthezeguation:

Using this valuev of Kyprogressively larger widths W of the :trou'ghrllistedzin .the;.table below) man She: determined" forrprogressively larger arbitrarily selected annularzaporticnsinf deck=:5

A mass of textile fibers, such as a mass of artificial staple fibers comprising regenerated cellulose which has been subjected to treatment with Water or aqueous media, and which is suspended in such liquid medium, may be continuously deposited from a trough having a specially constructed delivery edge according to our invention, in even and uniform layers upon the liquidpervious deck of a rotating vacuum table, and when vacuum is applied in the usual manner the liquid is rapidly and efiiciently withdrawn downwardly from all of the fibers constituting the mass. If desired the mass of fibers thus uniformly deposited on the deck may be subjected to further treatment thereon, such as, for example, washing to remove residual spinning bath, desulfurizing and removal of desulfurizing agent, bleaching and removal of bleaching agent, or to treatment with appropriate conditioning agents, such as softening agents, lubricating agents, etc., to render the fibers more amenable to further textile processing, such as carding, spinning, etc., which treatments may be carried out in sequence at predetermined segmental intervals of rotation of table 2. Due to the even distribution of the mass of fibers on the annular deck, when vacuum is applied below the deck in the usual manner, the treating liquid which has been sprayed or showered upon the fibers is drawn downwardly through the mass at a rapid and uniform rate and penetrates all of the fibers equally, with the result that fibers having uniform properties are obtained. After the liquid has been withdrawn, the blanket or layer of fibers may be continuously removed from the table and sent to a suitable container or the like, as previously described herein.

Although the invention has been shown and described with more particular reference to use thereof in connection with liquid suspensions of textile staple fibers, it will be apparent that the novel trough may be used whenever it is desired to deposit even, uniform layers of liquid suspensions of particulate material on a rotating annular surface for any purpose.

We claim:

In an apparatus which comprises a rotating foraminous annular surface disposed in a horizontal plane and a trough inclined from the vertical for depositing a liquid suspension of particulate material thereupon so that the amount of suspension deposited on any given unit width of the annular surface is directly proportional to the relative linear velocity of such unit, said trough having a delivery edge the projection of which on the annular surface effectively defines substantially an arc of a circle and the locus of the center of which circle lies on the annular surface on a radial line through the center of said surface extending at a right angle to the longitudinal axis of the trough, and the termini of which are coincide with the inner and outer peripheries of the annular surface, the locus of points on said are being ascertainable from the equation (Rt -Ro =K W (where R0 is the inside radius of the annular surface and K is a factor determinable by substituting in th equation the outside radius of the annular surface for R4; and the width of the trough for W) by dividing the width of the annular surface into a number of portions between imaginary concentric circles and substituting the value of the radius of the outer circle defining each portion for Rt in said equation, solving for W, and dividing the trough into parallel, longitudinally extending strips between imaginary lines spaced from that edge of the trough which extends to a point above the inside periphery of the annular surface distances corresponding to the values of W obtained, the intersections between the imaginary concentric circles and vertical planes through said parallel imaginary lines constituting the loci defining the arc,

DAN B. WICKER. CHARLES W. COX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 736,215 Chapman et al. Aug. 11, 1903 768,094 Turner Aug. 23, 1904 1,335,695 Oliver Mar. 20, 1920 1,772,684 Pink Aug. 12, 1930 1,776,568 ONeale Sept. 23, 1930 1,887,587 Ekeberg Nov. 15, 1932 2,219,954 Geiger Oct. 29, 1940