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Publication numberUS3859205 A
Publication typeGrant
Publication dateJan 7, 1975
Filing dateApr 17, 1974
Priority dateJan 31, 1972
Publication numberUS 3859205 A, US 3859205A, US-A-3859205, US3859205 A, US3859205A
InventorsImants Reba, Edward C Wolthausen
Original AssigneeCrown Zellerbach Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus and method for transporting fluid-entrainable particles
US 3859205 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

United States Patent 1191 Reba et al. Jan. 7, 1975 APPARATUS AND METHOD FOR 2.720.425 10/1955 Coanda .5302/63 TRANSPORTING FLUIDENTRAINABLE 3,047,208 7/l962 Coanda 239/l)l(l. 7 3,315,806 4/1967 Sigwart 1 209/l43 PARTICLES 3,575,353 4/l97l Sullivan 239/543 [751 lnvemors gm' g fiiz gf gg g FOREIGN PATENTS OR APPLICATIONS wash. 1,242,444 8/1960 France 209/145 [73] Assignee: Crown Zellerback Corporation, San Primary E,mminer--Rbert Halper FI'aHCISCO, Callf- Attorney, Agent, or FirmThomas R. Lampe; Corwin 221 Filed: Apr. 17, 1974 Horton [21] App]. No; 461,560 [57] ABSTRACT Related Application Data Particles entrained in fluid are rapidly propelled [63] Continuation of Ser- No 222 085 Jim 31 1972 through an elongated nozzle to an outlet where they abandoned contact a fluid barrier in the form of an air curtain which intersects the path of flow of the particles. 1521 vs. c1 209/3, 209/143, 209/145, cehteet of the PettieleS with the barrier Suhieete the 55/17, 239/116 7, 302/63 particles to violent shock which, depending on the na- [51] Int. Cl B07b 7/02 lure of particles being transported will tend to [58] Field Of Search 175/422, 54; 166/174; "P or rupture the PertieleS htto eehstitueht P 239/41 DIG. 7 543 545; 302/ 3; 210/ 5; nents. Th6 air curtain, clue IO a COflndtt effect," at- 209/145, 143, 31 132 155, 156 3 1; 244/42 taches itself to a flow-attachment surface spaced from CD the curtain generator to move any particles entrained with the curtain in a second flow path along this sur- {561 References Cited face. Other particles having sufficient inertia will pen- UNITED STATES PATENTS etrate the curtain so that particles are separated or classified, depending on the inertia they develop in the 3 3 5 gis Q nozzle. If the particles are wet, and the entraining fluid 2255227 x 2 52 209x X is air, a drying of the particles also takes place. 2,460,884 2/1949 Kjost 239/543 X 21 Claims, 6 Drawing Figures 1 k il 4 98 l l T 5m 90 96 lo 22 6 r 29 I2 43 l {9 M i 14 4. flit v 1. 0 54 0/ l l6 l ll L l 'L II"T f 1 PATENTED JAN 7 5 SHEET 10F 2 APPARATUS AND METHOD FOR TRANSPORTING FLUID-ENTRAINABLE PARTICLES This is a continuation of application Ser. No. 222,085, filed Jan. 31, 1972, now abandoned.

BACKGROUND OF THE INVENTION The present invention relates to a method and apparatus for rapid transportation of fluid-entrainable particles.

A phenomenon known as the Coanda effect has been known for many years, as exemplified by US. Pat. No. 2,052,869 Coanda. Briefly, this phenomenon can be described as the tendency of a fluid, which emerges from a slit under pressure, to attach itself or cling to and follow a surface in the form of an extended lip of the slit, which lip recedes from flow axis of the fluid as it emerges from the slit. This creates a zone of reduced pressure in the area of the slit and so air or any other entrainable material which is in the zone will become entrained and flow with the fluid which has attached itself to the extended lip. A Coanda nozzle may, therefore, be defined as a device which utilizes this phenomenon.

Different uses have been suggested for Coanda nozzles; and, for example, one such use has been in the transportation of liquid or solid particles as disclosed in US. Pat. No. 2,720,425 wherein internal nozzles are used.

It is also known(see, for example, an article by Dr. G. K. Korbacher, appearing in the January 1962 issue of Canadian Aeronautics and Space Journal, entitled The Coanda Effect at Deflection Surfaces Detached from the Jet Nozzle") that a fluid emerging from a slit under pressure will attach itself to and follow a receding deflection surface even though the surface is spaced from the slit, and such flow attachment also causes a zone of reduced pressure and subsequent entrainment of air or other material in the zone of the attached flow.

Even though Coanda nozzles have been effectively used to rapidly transport particulate material, as suggested by U.S. Pat. No. 2,720,425 Coanda, it is often desirable, especially if the material is somewhat agglomerated, to subject the material to a greater rupturing or disseminating force than is achieved by mere rapid in-line movement of entrained material, and it would be desirable to accomplish this during transportation rather than require a separate operation to do so. Materials having different characteristics (eg., different specific weights) are often transported in mixed form,

and it would be desirable to provide at least some degree of separation or classification of the material during transportation thereof. Other times, it is desirable to provide good mixing of the material being transported during transportation thereof.

SUMMARY In accordance with one aspect of the present invention, fluid-entrainable particles are entrained in a moving fluid and advanced with the fluid along a first flow path. A rapidly moving fluid curtain is provided which intersects this first flow path, and a flow-attachment surface is spaced from the fluid-curtain generator for the curtain to attach itself to and follow. The fluid curtain acts in a manner to subject the particles to shock due to rapid deceleration of the particles; and, if the particles have not developed sufficient inertia to penetrate the curtain, they will be reaccelerated and en trained for flow with the fluid curtain. While such shock may be sufficient to desirably break up'agglomerated particles, it also provides a zone of intimate mixing for particles which follow the fluid curtain. If there are other entrained particles that have developed sufficient inertia to penetrate the fluid curtain, such penetration will take place to separate the material which penetrates from the material which is entrained with the fluid curtain.

Other aspects of the invention reside in the particular means for entraining the particles, and yet other aspects reside in taking advantage of the Coanda effect to provide the flow-attachment of a fluid curtain to a surface to which the fluid curtain becomes attached and follows.

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the present invention is illustrated in the accompanying drawings in which:

FIG. I is a side elevational view of the apparatus of this invention, with parts broken away for clarity;

FIG. 2 is an enlarged side view of one of the nozzle assemblies of FIG. I, with parts broken away for clary;

FIG. 3 is an enlarged side view of another of the nozzle assemblies of FIG. 1, with parts broken away for clarity;

FIG. 4 is a sectional view taken on the line 44 of FIG. 2;

FIG. 5 is a reduced sectional view taken on the line 55 of FIG. 1, with parts removed for clarity; and

FIG. 6 is a sectional view taken on the line 66 of FIG. 1.

GENERAL DESCRIPTION Referring to FIG. 1, particulate material to be transportedis supplied from a hopper 10 to a first flow path 11 for the material, which flow path is defined by the internal surfaces of a first nozzle assembly 12. This material is entrained and rapidly transported in a suitable fluid, such as air, in the direction of the arrow leading from inlet end 13 to outlet end 14 of the first flow path 1 l.

A fluid-curtain generator in the form of a second nozzle assembly 15 is positionedadjacent the outlet end of the first flow path so as to generate a high velocity fluid curtain, such as high velocity air, which emanates from a fluid-exit slit 16 in the second nozzle assembly, to provide a fluid-curtain barrier which intersects the first material flow path 11 at the outlet end thereof. The

fluid curtain is directed from the slit 16 to a flowattachment surface 17, which at one end is in the form of a convexly curved, external end of nozzle 12 and the convexly curved end is spaced in close enough proximity to the slit 16 for the fluid curtain to attach itself to and follow surface 17 due to the aforementioned Coanda effect. In preferred form, the fluid curtain moves in a direction intersecting the first flow path at an angle substantially perpendicular thereto. The fluid curtain carries any entrained particles with it as it follows along external nozzle surface 18 in the direction of the arrows. This fluid curtain entrains additional air from an external source (such as the atmosphere) which enters from around the end 19 of shroud 20 to further reduce the particle concentration by entrainment of additional air. The internal surface of shroud 20together with the external surface '18 of the first nozzle assembly define a second flow path 21 having an inlet end in communication with the outlet end of the first flow path 11. The flow-attachment surface is so positioned as to preferably change the direction of flow of any particles entrained by the curtain at least 90 with respect to the direction the particles were traveling in the first flow path.

In the preferred embodiment illustrated in the drawings, any particles which have been entrained by the fluid curtain then move along the second flow path in the direction of the arrows, and the direction of movement of the particles in the second flow path 21 is opposite or 180 to the direction the particles have moved along the first flow path 11.

The entrained particles are moved from the second flow path into any suitable collector 22. While the type of collector is not critical, it has been illustrated as a receptacle having a screen 23 to permit air to pass out of the receptacle while retaining the particles therein.

At the outlet end prior to encountering the fluid curtain in the first flow path 1 l, the particles are at a rather high velocity, preferably at least 40 feet per second when the entraining fluid is gaseous, such as air. The fluid curtain emanating from slit 16 which intersects this flow path also is moving at a high velocity which is preferably at least 300 feet per second when a gaseous fluid, such as air, is used to provide the curtain. The particles upon contact with the fluid curtain thereby undergo a rather violent shock so as to cause a rupture or breaking up of any agglomerated particles. If the particles have not achieved sufficient inertia to penetrate the fluid curtain, they will be entrained in the fluid curtain and move along the second flow path 21. There may, however, be particles which have achieved sufficient inertia in the first flow path 11 to penetrate the fluid curtain. These particles, after penetrating the curtain, are moved by suitable means for conveying them in a direction away from the second flow path of the entrained particles.

Actually, the particles which penetrate the curtain may be classified further into two general types, namely, those which have developed sufficient inertia to penetrate the fluid curtain without substantial deflection of the particles, and those which are partially deflected by the air curtain, but which, due to centrifugal force, do not follow the air curtain but are expelled therefrom in a direction extending substantially 90 from the direction of flow in the second flow path 21. This further classification is optional and, if desired, all of the material which penetrates and is not moved along the second flow path 21 could be collected into a single fraction.

To summarize, the present invention in a preferred embodiment not only has capability of exerting forces by contact of particles with the fluid curtain which causesdeagglomeration and intense mixing in the zone of the curtain, but the invention also has capability of classifying particles into threegeneral fractions, depending on the inertia achieved by the particles at the outlet end 14 of the first flow path. A first fraction are the particles which do not develop sufficient inertia to penetrate the curtain or have lost inertia due to deagglomeration, and the particles in the first fraction are entrained by the fluid curtain and moved along the second flow path 21. A second fraction are those particles developing sufficient inertia to penetrate the curtain without being substantially deflected, and the particles in the second fraction enter the zone between suitable conveying means in the form of another Coanda flowattachment surface 24 anda shroud 25 where they are moved to any suitable collector. Fluid for entraining this second fraction is supplied from slit 26 which is located on the opposite side of the fluid curtain supplied by slit 16 from the first nozzle assembly 12. A third fraction are those particles developing an inertia between that developed by the first and second fractions. This third fraction is expelled from the air curtain into a suitable collector 27.

In order to obtain an understanding of the structural detail of a preferred embodiment for a first nozzle assembly 12 supported within generally cylindrical shroud 20, reference should be made to FIGS. 3 and 6, viewed in connection with FIG. 1. The shroud 20 is supported from any suitable supporting base 28 through the medium of a clamp member 29.

The first nozzle assembly 12 has a main body portion in the form of an elongated diffuser member 30 which is supported concentrically within and spaced from the inner surface of shroud 20. The diffuser member is annular in cross-sectional configuration in that it has a generally cylindrical outer surface 18, and an inner surface 31 which diverges from a throat portion 32 to outlet end 14. The external surface of the diffuser is provided with an externally-threaded,.recessed portion at the throat end 32 to receive a first fluid-exit slitforrning member 33. The member 33 is annular in cross-sectional configuration and one end thereof is provided with internal threads 34 for receiving the threaded end of the diffuser member. As seen at FIG. 3, the inner surface 35 of member 33 is convexly curved and the end 36 opposite the threaded end is utilized to define one side of fluid-exit slit 37. This slit 37 is located adjacent the inlet end 13 of the first flow path for the material. The inner surface 35 of member 33, together with the material inlet end of diffuser 30, defines a throat portion 32 for the first material flow path in that the surface 35 converges from the slit 37 toward the throat. The opposite side of fluid-exit slit 37 is defined by an inwardly projecting flange 38 on an annular, external slit-defining member 39. A recessed external surface 40 on member 33, together with internal surface 41 on member 39, defines a fluid-pressure chamber 42 which is in communication with slit 37, and the chamber receives fluid, such as air, under pressure from a suitable fluid-supply line 43. The fluid under pressure therefore emerges from the slit and, due to the Coanda effect, attaches itself to and follows surface 35 in a converging path to the throat 32. From the throat, the flow path diverges to the outlet end 14 of the nozzle assembly 12. This rapidly moving air establishes a zone of reduced pressure on the opposite side of slit 37 from surface 35 so that the rapidly moving air entrains additional air and any particulate material located in this zone of reduced pressure. Particles entrained by this fluid are thereby rapidly transported from inlet end 13 to outlet end 14 of the first flow path defined by internal surfaces of the first nozzle assembly.

It is desirable to provide means for adjusting the size of slit 37; and, to accomplish this, there is a threaded connection at 44 between the members 33 and 39. Therefore, if member 39 is turned in one direction, the slit size is increased, and if it is turned in the other direction, the slit size is decreased. In order to permit an operator to ascertain the extent of increase or decrease of the slit size without actual measurement, a springbiased detent 45 extends slightly from the recessed surface of diffuser member 30. Cooperating with the detent 45 is a plurality of countersunk portions 46 formed in and equidistantly spaced around the end of member 39. If, for example, there are 36 countersunk portions, the operator will know that the member 39 has to be turned to move the detent from one countersunk portion into the one next adjacent. Because of the threaded connection of member 33 to member 39, the operator can readily ascertain that each turn of 10, depending on the direction, will increase or decrease the size of slit 37 a predetermined amount, depending on the thread pitch in the threaded connection. A sealing ring 47 is wedged between the outer surface of member 33 and the inner surface of member 39.

To further complete the outlet end 14 of the nozzle assembly 12, an annular member 48 is affixed thereto through the medium of fasteners 49. The member 48 has a convexly-curved, external surface to provide the aforementioned flow-attachment surface 17 for the fluid curtain which exits from slit 16 in the second nozzle assembly 15.

A conical member 51 is secured to member 39 by appropriate fasteners 52, and the external converging surface of this conical member, therefore, acts as a diffuser in the sense that the cross-sectional area of the second flow path 21 is gradually increased as the particles move in a direction toward the point 53 of the conical member. A material supply duct 54 leads to an internal cavity 55 in the conical member, and this cavity is in direct communication with the first flow path 11 leading from slit 37, to continually supply material to be transported to the zone adjacent the slit for entrainment of such material by fluid exiting from the slit because of the aforementioned Coanda effect.

Structural details of a preferred embodiment of a second nozzle assembly are illustrated at FIG. 2. A generally cylindrical outer fluid conduit member 56 has a fluid supply duct 57 in communication therewith, and an exterior collar 58 having a sloping exterior surface 59 extends concentrically around and is secured to the outer surface of the conduit 56. An inner, generally cylindrical, fluid conduit member 60 is supported concentrically within and spaced from the outer member 56, and this inner conduit is in communication with supply duct 61. An extension 62 for conduit 60 is utilized to convey fluid under pressure from conduit 60 to fluid-exit slit 16 via openings 63 which lead to a cavity 64 in communication with this slit. The extension member 62 is connected to conduit 60 through the medium of an annular connector member 65. External, re-

cessed, surface portions 66 of the connector member 65 are threaded to receive the internal threads of annular, fluid-exit slit-forming member 67 which has a convex outer surface portion 68 leading away from slit 26 to form one boundary for this slit. The member 67 has countersunk portions 70 formed therein at one end thereof for receiving a spring-biased detent 71 in extension member 65 to permit adjustability of the size of slit 26 in the same manner as was explained in connection with adjusting the slit size in first nozzle member 12. A sealing ring 72 is wedged between the outer surface of connector member 65 and the inner surface of member 67.

Spacer rings 73 are positioned around extension member 62 to wedge a ring-like fluid-exit slit-forming member 74 into place between a circumferential external flange 75 on the extension member 62 and a circumferential external flange 76 on connector member 65.

Surface 77 on flange 75 defines one boundary of fluid-exit slit 16. The other boundary of slit 16 is defined by an extension lip 78 on a collar 79, which collar is threaded onto external threads 80 on extension member 62 so that the size of slit 16 can be adjusted by turning collar 79 in relation to member 62. The flange 75 and collar 79 have complementary, generally cylindrical, external surfaces and are of such a size so that the slit 16 can be placed concentrically within the same plane as-the plane defined by the extreme left end (as viewed in FIG. 1) of flow-attachment surface 17.

Means for permitting the operator to determine the extent of increase or decrease in the size of slit 16 is provided by a spring-biased detent 81 in surface 82 of collar 79, which detent is adjustably received in countersunk portions 83 in ring-like member 84, the latter number also being threaded onto the extension member 62. A sealing ring 85 is wedged between the outer surface of member 62 and the inner surface of member 79. A nose cone 86 is threaded onto the extreme right end (as viewed at FIG. 2) of extension member 62. As seen at FIG. 1, the nose cone projects from slit 16 concentrically into the end of the first nozzle 12, and the cone 86 serves as a guiding surface causing particles in the first flow path to be moving at substantially right angles to the fluid curtain when contact is made with the curtain.

Fluid under pressure reaches chamber 87 supplying fluid to the slit 26 via openings 88 through connector member 65. Fluid exiting from slit 26 attachesitself to surface 68 and follows this surface due to the aforementioned Coanda effect. This attached fluid entrains additional air and any particles which are in the vicinity of the slit. Externally spaced, cylindrical shroud 25, together with surface 24, defines a flow path for material moving along surface 24 in the direction of the arrows (FIG. 1).

As indicated above, collector 27 is utilized to collect those transported particles which have not developed sufficient inertia at the outlet of the first nozzle 12 to continue in a straight path so that the particles are deflected by the air curtain and expelled into this collector. As illustrated at FIGS. 1 and 5, the collector 27 has a curved, inner circumferential surface 89 which cooperates with back wall 89a so as to only partially enclose the space between shrouds 20 and 25, leaving a space 90 for additional air to be entrained from the atmosphere. Such entrainment of additional air is caused due to flow attachment on surfaces 17 and 24 by air exiting from slits l6 and 26. Optionally, an enclosed chamber could enclose space 90 with air being supplied under pressure to the chamber. An internal, curved divider 91 in the collector defines an inlet 92 for receiving air to be entrained through this inlet or received under pressure, and an outlet 93 for removing air and any material entrained thereby. The air from inlet 92 follows a tangential swirling flow path around the inner surface of the collector and leaves through outlet 93 carrying entrained material with it. Centrifugal forces throw the particulate material against surface 89 and the flow causes the material to follow this surface to outlet 93. Instead of using a positive pressure air to supply inlet 92, it is possible to utilize a Coanda nozzle (not shown) in outlet 93 which directs air and entrained material outwardly for removal from the collector.

An L-shaped supporting frame member 94, which is generally rectangular in cross-section, is secured to the clamp 29 to adjustably support the second nozzle assembly 15 therefrom. The supporting arrangement is such that the first and second nozzle assemblies are adjustably supported relative to each other to permit adjustment of the position of the fluid-exit slit 16 relative to external flow-attachment surface 17 of the first nozzle assembly. A complementary L-shaped supporting frame member 95 extends through shroud 25 and is secured at one end to the second nozzle assembly 15. The other end of the frame 95 has a nose portion 96 having a threaded aperture 97 extending therethrough and, as is clear from FIG. 1, the end of frame 95 is snugly positioned within one leg of frame 94. A crank arm 98 is rotatably supported on frame 94, and the crank is used to turn a threaded shaft 99 which is received in threaded aperture 97. Thus, rotation of crank arm 98 will impart horizontal movement to second nozzle assembly 15 with respect to first nozzle assembly 12 and so this provides means for adjusting the position of exit slit 16 on the second nozzle assembly 15 relative to the flow-attachment surface 17 on the first nozzle assembly Reference should be made to FIG. 1 for illustration of proper relative positioning of the component parts of the apparatus of this invention. The slit 16 should be in approximately the same place as a plane into which all points on the extreme left tip (as viewed at FIG. 1) of the attachment surface 17 would fall. It is possible, however, to obtain flow attachment of the fluid curtain from slit 16 onto surface 17 by moving the slit as much as one-half inch to the left of the plane. It is usually not desirable to move the slit to the right of the plane because, while it is still possible to get some flow attachment of the fluid curtain onto surface 17, positioning of the slit to the right of this plane generates back pressure and instability of flow in the first nozzle assembly 12.

As has been indicated above, means are provided for adjusting the width of slits 16, 37 and 26. It is desirable that this range of adjustability permits the slit width to be adjusted between a range of 0.001 inch to 0.150 inch. For most uses presently contemplated, the slit width which is chosen will lie between about 0.003 inch and 0.050 inch.

For a given slit width, an increase in the pressure of fluid that is supplied to the slit will increase the velocity of the fluid as it exits from the slit and moves over its flow attachment surface; and, therefore, the velocity imparted to the material entrained in this fluid will increase. Pressures that may be used in supplying transporting fluid to the slits may vary over a rather wide range, such as between about 1 psig and 400 psig, depending on the velocity it is desired to achieve and the nature of the operation desired to be performed on the material being transported. For most uses presently contemplated, the pressures of the fluid supplied to the slits will lie between about psig and 100 psig.

It is important that the velocity of the-fluid with its entrained flow supplied from slit 37 when it reaches the outlet end 14 of the first flow path 11 not be so great as to cause detachment of the fluid curtain supplied by slit 16 onto surface 17. Otherwise, none of the material would follow the second flow path 21. Therefore, in most instances, the operator will select the pressure he desires for fluid exit from slit 16, and initially cause fluid to exit from this slit and attach itself to follow surface 17. The operator will then gradually raise the pressure of the fluid exiting from slit 37 until a value is reached where the flow of the fluid curtain supplied from slit 16 detaches from the surface 17. This is the limiting pressure to slit 37. For the slit sizes chosen, the fluid supplied to slit 37 must then be at a pressure less than would cause flow detachment from surface 17. Conversely, an operator could first predetermine a required material through-put rate achieved by adjusting pressure and slit size for slit 37. The operator may then gradually raise the pressure and/or adjust slit size of exit slit 16 until a condition of flow attachment of the curtain from slit 16 to surface 17 is obtained.

As indicated above, the flow velocities, as governed by pressures and slit sizes, chosen for the entraining fluid in flow path 11, as compared to the flow velocity of the fluid curtain from slit 16, will depend on the type of operation that it is desired to perform on the material being transported. If, for example, the material being transported includes a mixture of two types of material (one type of which is capable of developing higher inertia than the other), and if separation of the two types of material is desired, then it will be desirable to establish as high a velocity as possible in flow path 11 without causing detachment of the curtain from attachment surface 17.

On the other hand, if it is mostly desired to cause a breaking up, mixing'or deagglomeration of particles being transported, then the velocity of the fluid curtain from slit 16 will be adjusted to be high in relation to the velocity of the particles transported in first flow path 11. In the latter instance, it will be highly preferable to utilize a higher pressure for the fluid that supplies slit 16, as compared to the pressure of the fluid that supplies slit 37.

While, as indicated above, velocities imparted to the tain from slit 16 to achieve a velocity of at least 300 feet per second, these stated velocities being for most types of particles and where a gaseous entraining fluid is used to transport the particles.

The specific type of material or particles to be transported, so long as they are entrainable in a fluid, are not critical to the present invention.

Particles are any fluid-entrainable materials which maybe entrained in the transporting fluid at the velocities employed. Thus, in certain instances, it may be desirable to transport such particles as ground metallic ores, metal particles, cereal grains, wood chips, cellulose fibers, fine powders, and many other materials by use of the method and apparatus of this invention.

Notwithstanding the fact that many additional types of particles may be transported, examples which are hereinafter presented illustrate the use of this invention with certain types of material, the treatment of which has been found to be especially advantageous. When reference is made in these examples to polyethylene fibers. such fibers are of a type that may be formed, for example, in accordance with the teaching of U.S. Pat.

9 applications Ser. Nos. 27,053 now abandoned, filed Apr. 9, 1970; and 69,194 now abandoned, filed Sept. 3, 1970. Such polyethylene fibers, after they have been suitably prepared for making synthetic paper, are of papermaking size, i.e., about 0.2 to 3 millimeters in length and have a diameter or width of about to 400 microns. When reference is made to rayon staple fibers,

dividual weights of the fibers, water and sand in the input mixture and, also, in each of the collected fractions were determined. Measurements were made of the particle size of the sand in the input mixture and in each fraction. The specific weight of the fibers is about 0.95, and the specific weight of the sand is about 2.56. The results are tabulated in the following Table I.

such fibers are those supplied by American Viscose Division of FMC Corporation and are inch in length and 3 denier. The rayon staple, as supplied, is in the form of many individual fibers closely packed together to form fiber bundles.

With further reference to the examples which follow, when reference is made to the F fraction, it means that fraction of material which has been entrained by the fluid curtain and has been collected by the collector 22. The R fraction is a fraction which has penetrated the curtain and is collected downstream of the surface 24. The C fraction is a fraction which has been collected in collector 27.

In the examples which follow, the apparatus which was used had the following physical and operating characteristics (unless otherwise noted):

Size Pressure (inches) (ps g) Pressure supplied by line 43 30 Width of slit 37 0.006 Length of nozzle from slit 12 to end 14 20.0

Diameter of throat 32 0,6 45 Internal diameter of diffuser at outlet end 14 1.53

Diameter of external surface 18 300 Internal diameter of shroud 20 5.50 Pressure supplied to slit 16 30 Width of sin 16 .020 External diameter of slit 16 .750 Horizontal distance (to the left as viewed at FIG. 1) of slit 16 to the vertical plane of the ex treme left end of surface 17 .06

Pressure supplied to slit 26 30 Width of slit 26 .003 External diameter of surface 24 (largest) 1.8

Internal diameter of shroud 25 4.0 Horizontal separation distance of ends of shrouds 20 and 25 1.5

Internal diameter of collector 27 14.0 Internal diameter of flange 8911 10.0

EXAMPLE 1 In this example, wet synthetic polyethylene fibers were intimately mixed with sand and the mixture was transported through the apparatus described above. 1n-

The foregoing data clearly indicates that most of the fibers, which have substantially less specific weight than the sand, are entrained by the fluid curtain and pass to the F fraction. The sand develops sufficient inertia to permit it to penetrate the fluid curtain, as is demonstrated by the fact that, of the total sand transported, less than 2 percent was carried with the fibers to the F fraction. Much less sand is contained in the C fraction than in the R fraction. The data further indicates that there is a tendency for the coarser sand to go into the R fraction and the finer sand to be deflected and captured in the C fraction. Moisture was removed from the fibers which passed to the F fraction, as evidenced by the fact that the input fibers were only 74 percent O.D. (oven dry), but the fibers in the P fraction were 93 percent O.D. (oven dry).

EXAMPLE 2 In this example, polyethylene fibers were utilized in a mixture which also had some small polymer chunks therein, the chunks being heavier than the individual fibers. included, also, in the mixture were some severely entangled fibers. A sample from this mixture (prior to being transported through the apparatus described above) was used to make a 6.25-inch diameter, 36 pound/ream basis weight, handsheet in a conventional manner by dispersing the mixture in water in a vessel, shaking the vessel one hundred times, and then using the dispersed mixture to form the handsheet on a forming wire in a conventional handsheet mold. The handsheet was calendered at pounds per lineal inch. The presence of polymer chunks and agglomerated fiber bundles in the handsheet is indicated by the extent and size of transparent spots that appear in the handsheet after such calendering, because such chunks and bundles have a tendency to transparentize. After passing another sample from the same mixture through the apparatus described above, handsheets were also formed and calendered from the F, R and C fractions. Measurements were made of transparent spots formed in each handsheet by using a template to measure the size and by counting the number. The results are tabulated in the following Table II.

TABLE ll Size and Number of Transparent Spots Over Less than 8mm 8mm 4mm 2mm 2mm input 45 61 96 *100 *300 R Fraction 7 18 40 76 *200 C Fraction I3 26 *133 *500 F FraCtlOn 0 0 70 The numbers of [00 or over are approximations.

The above data indicates there is an overall breaking up of fiber bundles, as evidenced by the reduction in large spots in all of the treated fractions, as compared to the input fraction. The data also indicates there is a tendency for the R fraction to obtain the larger chunks and bundles, and a tendency for the C fraction to obtain the smaller chunks and bundles because the smaller chunks and bundles have more of a tendency to be deflected by the fluid curtain.

EXAMPLE 3 In this example, wet polyethylene fibers which were 57 percent O.D. (oven dry) with a moisture content of 43 percent were passed through the apparatus as described above, except that the pressure of fluid supplied to fluid-exit slits 16 and 37 were varied. The pressure P is the air pressure supplied to slit 37, and the pressure P is the air pressure supplied-to slit 16. The pressure supplied to slit 26 is the same as that supplied to slit 16. Measurements were made of the percentage of the original fibers supplied which were collected at each of the fractions for each pressure combination, and measurements were made of the moisture content on an OD. (oven dry) basis for the F fraction. The results are tabulated in the following Table lll.

The above data indicates that as the pressure from slit 37 increases, compared to the pressure from slit 16, the velocity imparted to the fibers also increases in the first flow path, and so more fibers penetrate the fluid curtain. Data also indicates that some drying of the fibers takes place. The amount in the F fraction could be increased by moving the shroud 20 to the left (as viewed at FIG. 1) to intercept some of the particles that otherwise would pass to the C fraction. lf pressures are held constant, an increase in the size of slit 37will decrease the amount of material in the F fraction. An increase in the size of slit 16 will increase the amount of material in the F fraction. An increase in the amount of material in the R fraction can be accomplished by increasing pressure and/or slit size of slit 26.

EXAMPLE 4 In this example, ll6 grams of rayon staple fibers (in the form of fiber bundles, as supplied from the vendor indicated above) were placed in a graduated beaker and, without external compression, were found to occupy a volume of 0.8 liter. These fiber bundles were passed through the apparatus indicated above, except the pressure of air supplied to slits l6 and 37 was 40 psig. Sixty-seven grams of the fibers were collected as an F fraction, and 49 grams total was collected at the R and C fractions. The fibers collected at the F fraction were placed in a graduated beaker without external compression and found to occupy a volume of 6.0 liters; and, upon viewing, had the appearance of a mass of separated fibers. This indicates that the inventive treatment was effective to break up and fluff the original fiber bundles. The R and C fractions, when placed in a beaker, occupied a volume of 1.5 liters with a visual appearance ofa mixture of fiber bundles and separated fibers. 1

EXAMPLE 5 In this example, a sample including substantially equal quantities of dry polyethylene fibers and rayon staple fibers were placed in a vessel and it was attempted to mix the fibers together by hand-shaking but only a very poor mixture was obtained. This sample was then transported through the apparatus of the present invention and a sample obtained at the F fraction showed the polyethylene fibers and the rayon staple fibers to be intimately mixed with each other. This suggests that the forces encountered by the particles when they contact the fluid curtain are effective to intermix different types of fibers which are of such a nature as to be both transported by the fluid curtain. Rather than using different types of fiber, it is possible to use the method and apparatus of this invention to incorporate fine, lightweight powders into uniform admixture with fibers when both are simultaneously transported through the apparatus. It is also contemplated that vapors or very fine particles functioning as coating agents for the entrained material could be added to the entraining fluid to take advantage of the mixing zone provided by the fluid curtain to coat the transported particles.

From the above, it should be clear that the method and apparatus of the present invention has utility for achieving a number of desired results in transporting particulate material, depending on the nature of material being transported and the operating conditions chosen. Separation of particles capable of developing different inertias may be obtained. It is also possible to achieve good mixing and deagglomerating of particulate matter due to forces acting on the particles when they contact the fluid curtain. Drying of wet fibrous material has also been demonstrated.

While the foregoing specification has set forth specific embodiments and desirable uses of the invention in detail for purpose of making a complete disclosure, various other embodiments and uses will occur to those skilled in the art, but will fall within the spirit and scope of the invention defined in the following claims.

We claim:

1. Apparatus for transporting and treating fluidentrainable particles comprising:

a. means defining a first flow path having inlet and outlet ends;

b. means for advancing the particles with an entraining fluid along the first flow path from the inlet to the outlet end thereof;

c. a fluid-curtain generator having a fluid-exit slit adjacent said outlet of said first flow path and additionally having means for providingfluid under pressure to said generator fluid-exit slit to form a high velocity fluid-curtain barrier intersecting said first flow path; and,

d. a substantially curved flow-attachment surface spaced from said fluid-curtain generator fluid-exit slit across said first flow path and positioned in close enough proximity to said high velocity fluidcurtain for said high velocity fluid curtain, and any particles entrained thereby, to attach to said flowattachment surface and to follow said flowattachment surface due to the Coanda effect in a second flow path, whereby any particles entrained by said high velocity fluid-curtain will be separated from any other particles exiting from the first flow path outlet that have suff ciently higher inertial characteristics to permit their passage through said high velocity fluid curtain.

2. The apparatus as set forth in claim 1 wherein said first flow path is defined by internal surfaces of a first nozzle assembly, and said means for advancing the particles comprises means defining a first nozzle assembly fluid-exit slit located adjacent the inlet end of said first flow path to direct entraining fluid through said first nozzle assembly fluid-exit slit and along said internal surfaces in a direction from said inlet end to said outlet end.

3. The apparatus as set forth in claim 2 wherein said internal surfaces converge from said first nozzle assembly fluid-exit slit to a throat portion and diverge from said throat portion to said outlet end.

4. The apparatus as set forth in claim 2 wherein means for adjusting the first nozzle assembly fluid-exit slit size is provided.

5. The apparatus as set forth in claim 1 wherein said first flow path is defined by internal surfaces of a first nozzle assembly, and said flow-attachment surface comprises an external end of said first nozzle assembly.

6. The apparatus as set forth in claim 5 which further includes a shroud spaced outwardly from the external surface of the first nozzle assembly, said shroud and external surface together defining said second flow path having an inlet end in communication with the outlet end of said first flow path.

7. The apparatus as set forth in claim 6 wherein the direction of flow in said second flow path extends opposite to the direction of flow in said first flow path.

8. The apparatus as set forth in claim 1 wherein means for adjusting said fluid-curtain generator fluidexit slit size is provided.

9. The apparatus as set forth in claim 1 wherein said second flow path is in communication with an external fluid source for providing additional fluid to further reduce particle-fluid concentration by entrainment of the additional fluid.

10. Apparatus for transporting and treating fluid entrainable particles comprising:

a. a first nozzle assembly provided with internal and external particle-flow-directing surfaces, said internal surface having a particle inlet end and a particle outlet end and means for moving the particles in an entraining fluid in a first flow path from the inlet to the outlet end; a second nozzle assembly including means defining a fluid-exit slit positioned adjacent the outlet end of the first nozzle assembly, and means for directing the fluid through the slit to provide a fluid curtain moving in a direction intersecting the first flow path;

c. said external particle-flow-directing surface of said first nozzle comprising a substantially curved external flow-attachment surface spaced from said fluidcurtain means and in close enough proximity thereto for said fluid curtain, and any particles entrained thereby, to follow said flow-attachment surface in a second flow path.

11. The apparatus as set forth in claim 10 wherein the particle outlet end of said first nozzle assembly is annular in cross-sectional configuration, and external surfaces of the means defining the fluid-exit slit are generally cylindrical, and the slit is positioned in substantially the same place as that defined by the annular, particleoutlet end of the first nozzle assembly.

12. The apparatus as set forth in claim 10 wherein the first and second nozzle assemblies are adjustably supported relative to each other by means that permit adjustment of the position of the fluid-exit slit of the second nozzle assembly relative to the external flowattachment surface of the first nozzle assembly.

13. The apparatus as set forth in claim 10 wherein a shroud is supported in spaced relationship from the external particle-flow-directing surface of the first nozzle assembly to define a boundary for said second flow path for any particles entrained by said fluid curtain to follow said flow-attachment surface.

14. The apparatus as set forth in claim 10 which further includes means for conveying any particles which penetrate the fluid curtain in a direction away from the second flow path.

15. The apparatus as set forth in claim 14 wherein said conveying means includes means defining a second fluid-exit slit located on the opposite side of said fluid curtain from said first nozzle assembly for directing fluid in flow-attached relationship onto a second substantially curved external flow-attachment surface.

16. The apparatus as set forth in claim 10 wherein said conveying means includes a collector device.

17. The apparatus as set forth in claim 16 wherein said collector device includes a curved, internal surface in communication with a conveying fluid inlet and a particle outlet for supplying conveying fluid in tangential flow to the internal surface in a direction leading from the inlet to the outlet and removing particles from the outlet with the conveying fluid.

18. The apparatus as set forth in claim 14 wherein 7 said conveying means includes first conveying means for conveying any particles having sufficient inertia supplied in said first nozzle to penetrate the fluid curtain without substantial deflection of the particles by said fluid curtain, and second conveying means for conveying particles having less inertia supplied in said first nozzle than said particles removed by said first conveying means, but greater inertia than particles which follow said flow-attachment surface.

19. A method of transporting and treating fluidentrainable particles comprising:

a. advancing the particles entrained in a fluid from an inlet to an outlet end of a first flow path;

b. providing a high velocity fluid-curtain barrier which intersects the first flow path at the outlet end thereof by forcing a fluid through a slit communicating with said first flow path under pressure; and,

c. directing the pressurized high velocity fluid curtain onto a substantially curved external flowattachment surface receding from the curtain and spaced across the first flow path from said slit so moving such penetrating particles, and entraining for movement with the fluid curtain particles which do not develop sufficient inertia to penetrate the fluid curtain.

21. The method as set forth in claim 20 which further includes separating particles which penetrate the fluid curtain into a first fraction which move along a path substantially coextensive with the first flow path, and a second fraction which partially turn with the fluid curtain and are then expelled therefrom.

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Classifications
U.S. Classification209/3, 95/272, 209/143, 239/DIG.700, 209/145
International ClassificationB07B7/086, B07B7/02
Cooperative ClassificationY10S239/07, B07B7/02, B07B7/0865
European ClassificationB07B7/086B, B07B7/02