US2338619A - Method and apparatus for treating fibrous material - Google Patents

Description

Jan. 4, 1944. s, BOGATY 2,338,619

METHOD AND APPARATUS FOR TREATING FIBROUS MATERIAL Filed July 5, 1940 4 Sheets-Sheet 1 Jan. 4, 1944.

s. BOGATY 2,338,619

METHOD AND APPARATUS FOR TREATING FIBROUS MATERIAL Filed July 5, 1940 4 Sheets-Sheet 2 uawaxwagxmx Jan. 4, 1944. s. BOGATY 2,338,619

METHOD AND APPARATUS FOR TREATING FIBROUS MATERIAL Filed July 5, 1940 4 Sheets-Sheet 3 fiy Z I 1 FT s. BOGATY Jan. 4, 1944.

METHOD AND APPARATUS FOR TREATING FIBROUS MATERIAL Filed July 5, 1940 4 Sheets-Sheet 4 Patented Jan. 4, 1944 METHOD AND APPARATUS FOR TREATING FIBROUS MATERIAL Stanislaus Bogaty; Philadelphia, Pa., asslgnor to Proctor & Schwartz, Incorporated, Philadelphia, Pa., a corporation of Pennsylvania Application July 5, 1940, Serial No. 344,181

Claims.

This invention relates to treating, and particularly drying, animal, vegetable, mineral or synthetic fibrous stock spread in a layer of substantially uniform thickness on a foraminous support adapted to travel in a horizontal plane longitudinally through a suitable enclosure wherein the stock is contactedby moving currents of a gaseous treating medium enroute.

Prior to the present invention the drying medium has been directed downwardly against the entire area of the layer of stock simultaneously, in order to maintain the stock in position on the foraminous support constituting the upper run of an endless belt conveyer.

In order to avoid packing of the stock on the conveyer, in some instances, the circulation of the air in successive sections throughout the length of the drying chamber, has been alternately reversed. However, with this method, it has been necessary to provide a second or holddown conveyer of a foraminous character, in superposed relation to and traveling concurrently with the conveyer on which the layer of stock is placed, in order to prevent the stock from being blown oil the carrying conveyer. This arrangement entails additional expense, both in the initial installation and subsequent maintenance of the apparatus. (w

Another disadvantage of the hold-down system is, that, in order to obtain reversals of the air, it is necessary to provide partitions or other means at spaced intervals throughout the length of the drying chamber to control the paths of movement of the reverse air currents, and to provide means for producing the circulation in each of the partitioned sections. Such arrangements place a definite restriction on the number of times the passage of the air through the stock can be reversed within the length of the drying. I chamber.

The object of the present invention is to create a wave-like alternating compressive and expansive action in the stock, perpendicular to the plane of the foraminous support, in successive localized transverse areas of the layer, progressively, as the foraminous support transports the layer of stock longitudinally through the enclosure.

Another object of the invention is to confine the layer of stock on the support against shifting of any substantial portions thereof parallel to the support, to prevent development of holes through the layer and a consequent rushing of the drying medium therethrough which would disrupt the aforesaid wave-like compressive and expansive action in the stock.

The construction and operation of a drier made and operated in accordance with the principles of the present invention will be fully described hereinafter, reference being had to the accompanying drawings, of which:

Fig. 1 is a longitudinal section elevation of one end of the drier;

Fig. 2 is a transverse sectional elevation taken on the line 2-2 of Fig. 1;

Fig. 3 is an enlarged detail of the invention;

Fig. 4 is a view similar to Fig. 1, showing the preferred form of nozzle and conveyer construction; and

Fig. 5 is' an enlarged view of a portion of the structure of Fig. 4, illustrating the Wave-like compressive and expansive action more thoroughly.

As shown in Figs. 1, 2 and 4, the drier comprises a suitable casing l of any desired construction and dimensions and comprising suitably insulated enclosure walls 2, 2. Extending horizontally throughout the length of the casing I, in vertically spaced relation to the base or floor line 3, is an imperforate false bottom 4.

Spaced above the horizontal false bottom 4 is a carrying run 50. of an endless belt conveyer 5, the return run 517 of which is disposed in a chamber 6 formed below the false bottom 4.

The conveyer 5 may be composed of wire mesh screen, as shown at l in Figs. 1 and 2, but preferably the foraminous support is composed of perforated sheet metal, as shown at H in Figs. 4 and 5.

The foraminous body i' or 11, as the case may be, is supported at intervals throughout its length by transversely extending girts 8, 8. The girts, as usual, are secured at their opposite ends to side chains 9, 9 forming part of the conveyer,

and the side chains 9, 9 travel, as usual, on'

suitable supporting rails l0, III, which in turn are supported in any suitable manner by the framework of the drier. If desired, the belt 5 may be made in sections pivotally connected at and to the cross girts 8, 8, this being a well known conveyer construction.

At each side of the foraminous body I, or 11, of the conveyer, the side chains 9, 9 are provided with vertically extending side flanges II, II, to prevent escape of air and material laterally over the side edges of the carrying run of the conveyer.

Arranged above the carrying run 5a of the conveyer 5 is a series of air manifolds I2, i2. Each manifold l2 comprises a hood l3 of a general pyramidal form, to the apex of which is connected an air conduit M. Connected with the conduit I4 is the discharge side of a fan or blower casing l5. A suitable fan or blower I6 is rotatably mounted in the casing 15 on one end of an armature shaft ll projecting downwardly from an electric or other suitable motor mounted outside the casing I.

Air is driven under pressure by the fan or blower l6 into the conduit l4, and flows downwardly through the hood l3 of the manifold l2 onto the layer X of the fibrous stock undergoing treatment in the drier. A substantial portion of the air passes through the stock and the foraminous support I, or 11, to the space below the carrying run 5a of the conveyer, from which the air moves laterally across the false bottom 4 to and upwardly through a suitable passage at one side of the drier casing I, around the supporting rail ID at said side of the conveyer 5, from which the air is drawn by the fan or blower I6 into the blower casing I5 for movement into the conduit I4 and a repeat of the circulating cycle.

Between the conveyer rail I0 and one of the side walls 2 of the drier casing I, the air in circulation passes through a suitable heater or conditioning unit I9 of any well known type, whereby the air is heated or otherwise conditioned in circulation.

To prevent free particles of the fibrous material which are entrained in the circulating air from entering or passing through the unit I9, a double filter screen 20 is provided. The filter 20 consists of an upper run 20a and a lower run 20b of an endless belt composed of fine mesh screen, the side chains of said belt being supported by suitable rails 2|, 2|. The material retrieved by the filter conveyer 20 is carried thereby outside the drier casing I, and removed from the conveyer in any suitable manner, whereby the filter screen is retained in a clean condition and presents substantially no retarding effect on the circulation of the air therethrough.

In Figs. 1 and 2, the bottom of each of the manifolds I2 or the hoods I3 thereof is composed of a plurality of transversely extending slats 26, 26 which are spaced apart laterally to form air slots 21 21 therebetweeh, through which the air driven into the hood I3 by the fan or blower I6 is directed downwardly into contact with the layer X of stock supported by the carrying run 5a of the conveyer 5.

The blower I6 is operated to build up an air pressure within the hood I3, and the slots 21 are adapted to increase the velocity of the air as it escapes from the hood. The slots 21, 21

direct the air downwardly, in perpendicular relation to the layer of material X, in sheet-like streams having their lengthwise dimensions arranged transversely to the conveyer surface 5a, with the plurality of streams disposed in laterally spaced parallel relationship to each other, throughout the length of the drying chamber.

The air driven through the slots 21, under pressure, and moving at relatively high velocity causes the central planar portion of each sheetlike stream of air to contact with and pass through the layer of material X directly below and in alignment with the slot, as indicated by the arrows a. This causes the stock to be compressed as it passes under each slot 21, an indicated at b in Fig. 1.

According to the principles of the present invention, the material lying intermediate the parallel compressed areas I), b, as indicated at c, c, is caused to be raised upwardly with respect to the conveyer surface 5a, and to be fiufied by eddy currents of air, indicated by the arrows d, which are created as 'a side-wash to the central planar portion a of each stream.

To effect the formation of the above-noted eddy currents, the lower portions of the air slots 21, along the side edges of each slat 26, are flared outwardly and downwardly at and with respect to the central vertical plane of each slot 21. The air under pressure, and traveling at relatively high velocity through the slots 21, passes downwardly and expands laterally as it leaves said slots. edges of the adjacent slats 26, 26 govern the state of divergence of the side-wash currents d to produce the eddy currents. The rising and flufiing of the stock is caused by the eddy currents swirling above and penetrating the stock "in the areas c-c intermediate the compressed extending spikes or pins 30, distributed uniformly over its entire surface, at relatively-spaced points laterally and longitudinally thereof. The pins 30 are adapted to project into the layer of material X and prevent any lateral shifting thereof with respect to the carrying surface 50. of the conveyer.

The slatted bottoms 25, 25 of the several manifolds I2, I2 located side by side throughout the length of the drying chamber form a roof over the carrying run 5a, and the sheet-like streams of air passing downwardly against and perpendicular to the layer of material X on the carrying run 511. of the conveyer 5 return any loose fibre that may be freed from the layer X'by the raising and ilufling resulting from the penetration of the layer by the eddy currents. The eddy currents, by striking the under surface of the slatted wall 25, are turned toward the downwardly driving streams of air flowing through the slots 21, and carry loosened fibres'back into the streams, to be returned thereby to the layer X on the conveyer surface 511.

As shown in Figs. 4 and 5, the bottom I25 of each of the air manifolds is formed with a series of slots I21 extending transversely to the path of movement of the foraminous support 11 for the layer X, at spaced intervals along said path of movement.

The slots I21, I21 are disposed in a horizontal plane intermediate the bottom I25 of the manifold and thetop of the layer X of fibrous stock, and are formed by the laterally spaced lower terminal edges I28, I28 of upwardly divergent walls I29, I29 of each nozzle I30, the angle of divergency e--e of the side walls I29, I29 being equal at the opposite sides respectively of the central vertical plane j of the nozzle, which is perpendicular to the plane 9-9 of a foraminous stock supporting surface 11, whereby the v air is delivered downwardly against the upper surface of the layer of stock X in sheet-like streams y y perpendicular to the surface 11, and effects compression of the stock in relatively narrow localized transverse areas :r-r, spaced apart along the length of travel of the foraminous supporting surface 11 for the layer X.

While a substantial portion of the air of each stream 11 passes through the perforations 18 of the surface 11 a goodly portion of the air impinges against the solid portions 19 of the surface 11 and is deflected upwardly and laterally with respect to said surface and the general The divergent portions 28, 28 of the vertical plane of the streams y, as indicated by the arrows yl, Fig. 5. These deflected upwardly traveling portions yI, yI of the air streams raises and fiuifs the stock in the areas :cI, ml which lie intermediate the compression areas :0, :r, the raising and fluifing areas :nI, :rI being relatively wider than the narrow, compression areas it, 2:, between which the wider fiufllng areas extend from side to side of the longitudinally moving foraminous surface 11 by which the layer X is transported through the enclosure].

As the surface 11 transports the layer of stock X through the enclosure I, it serially ing tercepts the vertically moving streams of air 1 y and the alternating compressions and raisings in the areas a: and ml respectively progress along the advancing layer of stock. This causes agitation of the stock in the layer which disintegrates lumps in the stock which cannot be mechanically broken up without breaking the fibres of which the matts or lumps are composed.

In order to obtain a satisfactory compressive and expansive action the width w of the slots I21, I21 should bear a definite relationship to the spacing s of the slot centers. that the ratio of not less than 6 to 1 between the spacing s of the centers f, j of the nozzles I30, I30 and the widths w of the respective slots I21 will give satisfactory results, with the best results obtained, for example, under an approximate 24 to 1 ratio, as shown in Fig. '5. While even higher ratios may be employed it has been found that the stock, under such circumstances, has a tendency to lie dormant during a portion of its travel between successive nozzles. The best results are obtained by keeping the stock in motion, perpendicular 'to the support as it is conveyed horizontally by the support. Consequently, when using a ratio between a minimum of 6 to 1 and a maximum of 30 to 1, a constant agitation is effected. With a ratio below the minimum noted above, the downward pressure becomes more or less universal over the entire area of the layer X.

In some instances it may be advisable to provide a differential action, as the layer X is transported through the dryer. For example, a quick action may be desirable at and adjacent the entrance to the drying chamber with the cycle periods increasing in length as the stock advances toward the exit from the drying chamber, or the reverse may be resorted to under different circumstances with different materials, i. e. the cycles may be longer in the portion of the chamber adjacent the entrance and shorter in the portion near the exit.

Such differential action may readily be accomplished by spacing the nozzles I21 differently or in increasing or decreasing progression with the maximum and minimum ratios noted above.

During the compression and expansion of the stock, as the stock travels horizontally, the stock slides up and down along the vertical pins 30, 3|] which function as guides for the stock and keeps it from shifting horizontally on and relative to the foraminous supporting surface 11.

As shown in Fig. 5, the common plane of the lower terminal edges I28, I28 of the nozzle slots I21, I 21 is spaced below the plane of the bottom wall I25 of the manifold I2, and the divergency of the side walls of one nozzle I30 with respect I to the side walls of the adjacent nozzles I30 produces ,air spaces a, z with angular deflecting surfaces zI, a2, 22 by which the air is turned and It has been found v 3 directed downwardly and into the paths of discharge from the nozzle slots I21, I21 by which more or less swirling eddy currents corresponding to those previously described are produced.

It will be understood that the endless belt 5 in each of the structures of Figs. 1 and 2, and

Figs. 4 and 5 preferably extend beyond the opposite ends of the drier I and around suitable supporting drums or wheels; and that the belt as a whole may be driven from any suitable source of power through any suitable form of transmission without departing from the present I penetration of the layer of stock beneath said face within each of said narrow areas by said impinging streams of air, and expanding relatively wider intermediate areas of said layer by deflecting portions of said air streams laterally therefrom into said intermediate areas of the stock.

2. The method which consists in pneumatically compressing relatively spaced narrow areas of a layer of fibrous stock simultaneously at fixed points respectively along a, path of intended travel of said layer by impinging streams of air against one face of the layer within said narrow areas respectively, effecting penetration of the layer of stock beneath said face within each'of said narrow area by said impinging streams of air, expanding relatively wider intermediate areas of said layer by deflecting portions of said air streams laterally therefrom into said intermediate areas of the stock, and advancing said layer along said path relative to said fixed points to effect said compressings and expandings alteriiately throughout the length of said traveling ayer.

3. The method which consists in advancing a continuous layer of fibrous stock horizontally, pneumatically compressing narrow transverse areas of said layer simultaneously in transverse planes perpendicular to said layer and spaced apart longitudinally of the path of travel of said layer by impinging streams of air against one face of the layer within said narrow areas respectively, effecting penetration of the layer of stock beneath said face within each of said narrow areas by said impinging streams of air, and expanding said stock in relatively wider transverse areas intermediat said narrow compression areas as said layer advances through said perpendicular planes successively by defiecting'portions of said air streams laterally therefrom into said intermediate areas of the stock.

4. The method which consists in supporting a continuous layer of fibrous stock on a foraminous surface in a horizontal plane, directingsheet-like streams of air downwardly against said layer simultaneously in transverse planes perpendicular to said layer and said surface at spaced intervals longitudinally thereof, and advancing said surface and said layer concurrently in said horizontal plane through said perpendicular streams of air, compressing the stock in relatively narrowareas respectively at said perpendicular planes by said sheet-like streams of air respectively, and expanding said stock intermediate said compression areas progressively along said layer as said layer passes through said air streams by deflecting portions of said sheet-like streams laterally therefrom into the stock disposed intermediate said compression areas.

5. The method which consists in supporting a continuous layer of fibrous stock on a foraminous surface in a horizontal plane, directing sheetlike streams of air downwardly against said layer simultaneously in transverse planes perpendicular to said layer and said surface at spaced intervals longitudinally thereof of at least six times the thickness of each of said air streams, advancing said surface and said layer concurrently in said horizontal plane through said perpendicular streams of air, compressing the stock in relatively narrow areas respectively at said perpendicular planes by said sheet-like'streams of-air respectively, and expanding said stock intermediate said compression areas progressively along said layer as said layer passes through said air streams, by deflecting portions of said sheet-like stream passing downwardly and completely through said layer of stock and perforations in the underlying foraminous surface and compressing the stock in relatively narrow areas at said planes respectively with other portions of the air of each stream impinging againstimperforate portions of said foraminous surface and rebounding upwardly and thereby expanding said stock in areas intermediate said compressed areas, and advancing said surface and said layer concurrently in said horizontal plane through said perpendicular streams of air.

7. The method which consists in supporting a continuous layer of fibrous stock on a foraminous surface in a horizontal plane, directing sheet-like streams of air downwardly against said layer simultaneously in transverse planes perpendicular to said layer and said surface at spaced intervals longitudinally thereof, advancing said surface and said layer concurrently in said horizontal plane through said perpendicular streams of air, compressing the stock in relatively narrow areas respectively at said perpendicular planes by said sheet-like streams of air respectively, and expanding said stock intermediate said compression areas progressively along said layer as said layer passes through said air streams, by deflecting portions of said sheet-like streams laterally therefrom into the stock disposed intermediate said compression areas, and confining the layer of stock against substantial movement parallel to said surface during movement of said stock perpendicular to said surface.

8. A drier for fibrous stock, comprising a continuous flat foraminous conveyer surface operable in a horizontal plane for supporting and transporting said stock in a continuous layer longitudinally through the drier, a plurality of air nozzles disposed above said surface and each including a pair of opposite symmetrically shaped side walls forming a long narrow air discharging slot extending transversely of said surface with said slots spaced apart along the path of movement of said surface and the layer of stock thereon and arranged to direct air downwardly against said layer in sheet-like streams in planes perpendicular to said surface and said layer of stock to compress said stock in narrow transverse longitudinally spaced areas thereof simultaneously as said layer of stock is advanced through the drier 0n and by said surface, means for forcing air under pressure from said discharge slots to effect said compressions and penetration of the stock by the air of said streams, and imperforate areas in said foraminous surface to deflect portions of the penetrating air,laterall through the stock thereby expanding the stock intermediate said compression areas.

9. A drier for fibrous stock, comprising a continuous flat foraminous conveyer surface operable in a horizontal plane for supporting and transporting said stock in a continuous layer longitudinally through the drier, a plurality of air nozzles disposed above said surface and each including a long narrow air discharging slot extending transversely of said surface with said slots spaced apart along the path of movement of said surface and the layer of stock thereon and arranged to direct air downwardly against said layer in sheet-like streams in planes perpendicular to said surface and said layer of stock to compress said-stock in narrow transverse longitudinally spaced areas thereof simultaneously as said layer of stock is advanced through the drier on and by said surface, means for forcing air under pressure from said discharge slots to effect said compressions and penetration of the stock by the air of said streams, and imperforate areas in said foraminous surface to deflect portions of the penetrating air laterally through the stock thereby expanding the stock intermediate said narrow transverse areas, said slots being spaced apart a distance at least as great as six times the width of each slot in order to allow for said expansions of the stock intermediate said compressions thereof.

10. A drier for fibrous stock, comprising a continuous flat foraminous conveyer surface operable in a horizontal plane and composed of perforated sheet material for supporting and transporting said stock in a continuous layer longitudinally through the drier, a plurality of air nozzles disposed above said surface, means for forcing air under pressure through said nozzles, each nozzle comprising oppositely disposed symmetrical walls forming a long narrow air discharging slot extending transversely of said surface with said slots spaced apart along the path of movement of said surface andthe layer of stock thereon and arranged to direct air downwardly against said layer in sheet-like streams in relatively spaced planes perpendicular to said surface, with a portion of the air of each stream passing through said layer of stock and the perforations of said sheet to compress the stock in narrow transverse areas below said slots, and with other portions of the air of each stream impinging against solid portions of said sheet surrounding said perforations and being thereby deflected upwardly into said layer of stock to expand said stock in areas intermediate said compressed areas, to effect drying action in said layer of stock progressively along the length thereof.

STANISLAUS BOGATY.

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