US3374106A - Material drying method and apparatus - Google Patents

Description

March 19, 1968 1 |||Q- THYGESON, 5R 3,374,106

MATERIAL DRYING METHOD AND APPARATUS l Filed May 14, 1964 `s sheets-sheet INVENTORZ BY JOHN R. THYGESONrSR,

March 19, 1968 J. R. 'THYGE-soN, SR 3,374,106

MATERIAL DRYING METHOD AND APPARATUS Filed May 14, 1964 3 Sheets-Sheet 2 no3. f

INVENToR'. JOHN R. THYGESON SR.

BY MW ATTYS.

March 19, 196.8 J. R. THYGEsoN, SR 3,374,106

MATERIAL` DRYING METHOD AND APPARATUS Filed May 14, 1954 5 Sheets-Sheet 5 FIGS.

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United States Patent Office 3,374,106 Patented Mar. 19, 1968 3,374,106 MATERIAL DRYING METHOD AND APPARATUS John R. Thygeson, Sr., Fox Chase Manner, Pa., assignor to Proctor & Schwartz, Inc., Philadelphia, Pa., a corporation of Pennsylvania Filed May 14, 1964, Ser. No. 367,350 10 Claims. (Cl. 117-1053) ABSTRACT 0F DISCLSURE A method and apparatus for treating material, particularly batts or webs of non-oriented, loosely cornpacted fibrous material, by conveying it through an enclosed housing having a treating chamber and treating medium conditioning means including air distribution means having an outlet port confronting the batt through which treating medium is discharged. In the form of the invention illustrated, the treating medium distribution means consists of an enlongated box having an outlet port, and bafe means comprising a pair of elongated bafiie plates is provided which extends coextensively with `the outlet port and angularly relative to one another and to the direction of flow of the treating medium from the outlet port. This baille arrangement divides the flow of treating medium into three zones, two outer zones and a center zone thereby creating a pressure and velocity dfference in the zones whereby treating medium diverted to the outer zones creates a suction which draws treating medium up through the batt in the center zone to create a slight lofting of the batt.

This invention relates to method and apparatus for drying materials.

The present method and apparatus are especially adapted for processing batts or Webs of non-oriented, loosely compacted fibrous material. Battsl of this type are used, for example, as interlinings, filters, etc., and in these applications it is desirable that the batt have certain resilience, loft, density, final thickness and porosity characteristics for most effective results in its use as a liner, filter, etc. In some drying apparatus for drying these batts, the hatt or web is sprayed with a binder on one face and after spraying, advanced through the drying chamber of the apparatus. The batt is then reversed so that the other face may be sprayed with the binder and again passed through the drying chamber. A drying medium is circulated through the drying chamber to dry and cure the binder. The binder serves to give the batt body.

The means for circulating drying medium through the drying chamber includes a series of air distribution boxes extending transversely to the direction of travel of the batt and spaced along the entire length of the drying chamber. These air distribution boxes have tapered top and side walls, an inlet opening at one end through which the drying medium enters the box and an elongated narrow slot providing a discharge outlet at the bottom of the box confronting the batt with a plurality of partitions dividing the slot into a plurality of small discharge nozzles. By this arrangement drying medium entering the box is discharged through each of the nozzles directly against the surface of the batt confronting the nozzles, the configuration of the box being such that the discharge velocity of the drying medium through all the nozzles is substantially uniform. It has been found that in order to achieve effective curing of the binder and drying of the batt, that is, processing ofthe batt, the velocity of the air discharged through the nozzles be in the range of 1500 to 3500 feet per second. However, with this arrangement one of the problems is that the drying medium directly engaging the face of the web tends to flatten or compress the batt so that some of the highly desirable characteristics of the finish processed batt are destroyed. More specifically it has been found that if the batt is prematurely compressed, that is, before the binder is cured, there is a matting together of the fibers which destroys the desired porosity and resiliency of the batt. Thus, if the batt is compressed to too great a degree, the resilience, loft, density, final thickness and porosity thereof are adversely affected and the batt will not be able to be used effectively for its intended purpose.

In accordance with the present invention, means is provided for controlling the circulation of the drying medium in the Vicinity of the batt and in such a manner that the final desired condition or characteristics of the batt may be controlled more accurately.

More specifically, in accordance with the present invention, there is provided baie means in the path of liow of the drying medium from the discharge nozzles, which baffle means serves to diffuse or break up the air flow into zones thereby preventing direct impingement of the air against the face of the batt. In the illustrated embodiment of the invention, baille means comprises a pair of elongated baffle plates disposed adjacent the discharge I nozzles of the air distribution box coextensive therewith. The plates are disposed angularly relative to one another and to the direction of flow of the drying medium from the discharge nozzles. The effect of the baffle arrangement is to cause the air discharged through the nozzles to be diffused or broken up so that the full thrust of the drying medium is not directly onto the surface of the batt.

It has been found that with this ba'le arrangement, the `air discharged through the nozzles is broken up in such a way that there is actually a slight lofting of the web as it passes through the drying chamber, thereby avoiding harmful compression of the batt as heretofore was the case whereby the finish processed batt is resilient and lofty. Moreover it has been found that the circulation of drying medium effected by the baffle arrangement increases the drying eiciency. Further by this arrangement, the mass movement of air directed toward the batt `or circulated through the air nozzles may be increased appreciably thereby increasing the drying rate. Accordingly, with the foregoing in mind an object of the present invention is to provide a method and apparatus for continuously drying material such as batts made of non-oriented, loosely compacted fibers wherein the circulation of the drying medium is controlled in a manner whereby the processed batt is characterized by a predetermined desired resilience, loft, density, final thickness and porosity.

Another object of the present invention is to provide a method for continuously drying material to provide a finished product characterized by optimum characteristics such ,as loft, resilience, density, final thickness and porosity and apparatus for carrying out the method Which is of comparatively simplified construction and may be manufactured and installed economically.

A further object of the present invention is to provide drying apparatus and method characterized by novel features whereby the drying eiiiciency of the dryer is increased.

These and other objects of the present invention and the various `features and details of the operation of the apparatus and method and the construction of the apparatus are hereinafter more fully set forth with reference to the accompanying drawings in which:

FIG. l is a plan View of a dryer in accordance with the present invention with parts broken away to show the internal construction thereof;

FIG. 2 is a side elevational view of dryer shown in FIG. 1 also with parts broken away;

FIG. 3 is an enlarged sectional view 3-3 of FIG. 2;

FIG. 4 is an enlarged fragmentary taken on lines 4-4 of FIG. 3;

FIG. 5 is an enlarged fragmentary taken on lines 5-5 of FIG. 3; and

FIGS. 6 and 7 are enlarged sectional views taken on lines 6-6 and 77 respectively of FIG. 5.

Referring now to the drawings and considering now the primary components ofthe apparatus in terms of function, a batt B of non-woven, loosely compacted fibers is delivered to the feed or entrance end of the dryer by suitable means to the lowermost foraminous conveyor 1 of a series of tiered forarninous conveyors which conveyor 10 is suitably actuated by a motor M1 and belt transmission T1 for movement in an endless path to transport the batt through the generally enclosed housing of the dryer D. At the feed end of the dryer D, suitable spray means S is provided to deposit a binder such as latex, an acrylic resin or other thermoplastic material to one face of the batt B. Thereafter the conveyor 10 moves the sprayed batt B through the drying chamber Cd of the dryer. At the opposite or delivery end of the dryer D, the batt B passes around a guide roll R1 and the opposite face of the batt B is sprayed by a second spray unit S2. The sprayed batt B is again conveyed back through the drying chamber Cd on the second, or in the present instance, middle conveyor 12 of the tier of conveyors which is actuated for movement in an endless path by a motor vM2 and belt transmission T2. As the batt approaches the feed end of the dryer D, the direction of the batt B is again reversed by passing around rolls R2 and by means of the uppermost conveyor 14 the batt B again passes through the drying chamber Cd so that the batt may be discharged at the delivery end of the dryer. This conveyor is actuated from motor M1 and a belt transmission T3. The processed batt B then leaves the delivery end of the dryer for further processing. During movement of the batt through the dryer D, a heated drying medium is circulated through the drying chamber Cd to effect curing of the binder and drying of the batt.

Referring now to the drawings and particularly to FIGS. l and 2 thereof, the dryer comprises an elongated generally enclosed housing 11, in the present instance, divided into two sections, S1 and S2 of substantially identical construction. These sections S1 and S2 are mounted end to end to form a continuous enclosed dryer housing. As best illustrated in FIG. 3, each section of the dryer housing 11 includes a top wall 20 and opposing side Walls 22 and 24. The front section S1 of the dryer housing includes a front wall 26 having suitable openings O1 therein to accommodate the conveyors and movement of the batt into and out of the housing and the rear section S2 has a rear wall 28 also having openings Oo therein to facilitate passage of the batt into and out of the housing.

In order to minimize leakage of drying medium from the housing 11 through the openings O1 and Oo, an air curtain may be provided at the feed and delivery ends of the dryer. To this end, there is provided a vertical partition 91 which extends transversely of the housing and which isl spaced from the front wall 25 to define an air curtain chamber 93 at the feed end of the housing. Ductwork l95 communicating with the air curtain chamber 93 including a fan 97 is provided to draw air from the air curtain chamber 93 whereby leakage of drying medium from the housing is minimized. A similar air curtain chamber 101 defined by a partition 103 is provided at the delivery end of the housing. Ductwork 105 and a fan 107 are provided to draw air from the air curtain chamber 101.

Each section of the dryer is subdivided into several taken on lines sectional view sectional view compartments including the drying chamber Cd extending lengthwise of the dryer and which, as illustrated in FIG. 3, is defined by a horfzontally extending panel 40 running the length of the dryer and spaced from the top wall 20, a vertical panel 44 spaced from the side wall 22 and the side wall 24. The space between the panel 40 and top wall Z0 defines a conditioning chamber ft2, and the space between the side panel 44 and side Wall 22 defines a distribution chamber 46.

A motor operated fan is mounted in the p-anel 44 with its intake -or suction side communicating with the conditioning chamber 42 and the impeller, or discharge side, disposed to -direct drying medium drawn from the conditioning chamber 42 to the distribution chamber t6 as illustrated in FIG. 3.

A plurality of air boxes is provided along the length of the dryer in two rows, one row above the upper run of the intermediate conveyor 12 and the other row above the lowermost conveyor 10. Each of the boxes 60 extends transversely to the direction of movement of the conveyors and as illustrated in FIG. 2, the boxes are closely spaced the length of the conveyors. Each box 60 has an open end 62 communicating with the distribution chamber 46 so that air entering the distribution chamber is directed into the box and a closed end as at 65. Each of the boxes 60 as illustrated, has a top wall 67 and opposing side walls 69, all of which converge toward the closed end of the box. In the bottom of each box is an elongated generally rectangular outlet port 71 which extends approximately the width of the conveyor and which has mounted therein a honeycomb 66 to divide the outlet port '71 into a series of generally square nozzle openings 68. By this arrangement, as the drying medium enters the box, it is directed downwardly through the individual nozzle openings 68 and by reason of the configuration of the box, the velocity of air discharged through each of the nozzle openings 68 is substantially uniform. The drying medium discharged through the nozzle openings 63 passes downwardly against the batt on the upper run of the conveyors 10 and 12 and then passes to a discharge chamber 70 running the length of the housing to the side thereof opposite the distribution chamber 46. A series of lint screens 72 is provided along the upper extent of the discharge chamber 70 through which the drying medium is drawn by the fan S0. At the side of the conditioning chamber opposite the fan 50 adjacent the lint screens 72, there is provided suitable 'heating means, in the present instance, a gas heating unit '73 to heat the drying medium as it is drawn through the conditioning chamber by the fan.

In accordance with the present invention, bafiie means is provided adjacent the outlet port '.71 of each of the air distribution boxes 60 which serves to control the flow of the drying medium discharged through the air nozzles 68 in a manner to effect slight loftin g of the batt and prevent compression or compacting thereof which would harmfully affect the desired characteristics of the processed batt. In the present instance, the bafiie means comprises a pair of elongated generally rectangular plates and 82 which are angularly disposed relative to one another and to the direction of flow of the treating medium from the air outlet port 71. Preferably the plates 80 and 82 openly diverge toward the face of the batt as illustrated in FIG. 5. The ends of the baffle plates are supported on end support brackets 84 which depend from the air box 60 adjacent opposite ends of the outlet port 66. As best illustrated in FIG. 5, the upper edges 81 and 83 of the plates S0 and 82 are spaced closely together and close to the outlet port. Further, the edges S1 and S3 are spaced inwardly from the sides of the outlet port to divide air discharged therethrough into three zones, zone X between the plates, zone Y outboard of the plate 80 and zone Z outboard of the plate 82.

The plates 80 and S2 are adapted for adjustment to vary selectively the angular relation of the plates to one another and to the direction of flow of the air discharged from the outlet port whereby the flow pattern of the air in the vicinity of the batt may be varied to achieve the desired cfrculation for a given batt being processed. In order to facilitate selective adjustment of the bafiie plates relative to one another and to the direction of flow of the treating medium through the air nozzle, each of the plates is pivotally mounted to the brackets 84 at opposite ends adjacent the inner longitudinal edge thereof, that is, the edge closest to the outlet port 71 in the box 60. Thus each of the plates may be swung in the direction indicated by the arrow to selectively vary the angle of divergence of the plates 80 and 82. In the present instance, each of the support brackets 84 is provided with an arcuate slot 86 therein to receive a screw fastener or the like 87 so that the plates may be pivoted to a desired position and secured in that position by the fastener 87. By this arrangement, it has been found that the air from the outlet port diverted to zones Y and Z creates a slight suction or vacuum which draws or induces a small amount of air up through the batt in the zone X and hence creates a slight lofting of the batt. This induced circulation through the batt as indicated in FIG. 5, increases the drying rate and hence the drying efiiciency of the dryer.

Consider now the operation of the dryer when processing a continuous run of fibrous material in the form of a batt. The batt B is delivered by suitable conveyor means to the lowermost conveyor 10 at the feed end of the dryer where t'he spray means S deposits a binder on the top face of the batt B. The conveyor 10 then advances the battB for its first run through the dryer past the plurality of air boxes 60. Drying medium circulated by the fan 50 enters the lowermost series of boxes through the distribution chamber 46 and the opening 62 in one end thereof. The air passing through the boxes and out each of the nozzles of the discharge outlet engages the baliies S and 82 disposed adjacent the nozzle discharge opening in the path of flow of the drying medium. The bafiies serve to disperse the drying medium and divert the flow into three zones X, Y, and Z in a manner shown in FIG. whereby a slight liufiing-of the batt occurs in the region between the outer extremities of the baies 80 and 82, zone X. It has been found that this slight lofting of the fibers in this region is due to the pressure differential between the top face of the batt and the region below the batt which is caused by deflecting the air by means of the baliies. During the course of movement of the batt along the bottom conveyor 10, curing of the binder takes place. The batt B then reverses direction around the roll R1 and a binder is sprayed on the reverse side by the spray unit S2 adjacent the second conveyor at the discharge end of the dryer. During movement of the batt through the dryer on the intermediate conveyor 12, the drying medium again is directed into a plurality of air boxes 60 provided along the length of the conveyor which also has the barile means 80 and 82. The direction of the batt then is reversed around the rolls R2 and makes a final pass through the dryer on the outermost conveyor 14. It is noted that with respect to FIG. 3, the continuous lcirculation of air in the dryer housing is in the direction indicated by the arrows. Thus, as noted when the drying medium enters the discharge chamber from the air boxes, it passes up through ,a series of lint screens 72 which purify the air. ,The drying medium is then circulated by the heating means and vdrawn through the conditioning chamber 42 by the fan `50 and expelled to the distribution chamber 46. An inlet opening 119 is provided in one wall of the housing having suitable damping means 121 to permit fresh air to be added to the air circulated in the dryer if desired.

The angular position of the bafiles 80 and 82 depends on a number of variables such as velocity of the drying medium at the outlet port, type of fibers being processed, initial thickness of the batt, desired final thickness and density of the batt. The final adjustment of the baflies is therefore dependent on the operator who samples the batt after a short run and adjusts the baffles until the processed batts has the desired characteristics. It has been found that by processing fibrous material in the form of batts in this manner, the desired characteristics of the process batt, such as resilience, loft, density, final thickness and porosity, may be controlled accurately. Moreover, it has been 4found that efficient drying of the batt and efiicient curing of the binder are achieved by the provision of the baffles in the region of the discharge nozzles.

While the present invention has been described in connection with fibrous material in the form of batts, it is readily apparent that it is also useful in treating or drying other fibrous or particulate materials and also thin thermoplastic films such as polypropylene. The invention also may be usefully applied in curing of rubber sheets and the like. In the case of thin films, it has been found that in prior dryers where the air impinged directly on the film there was the problem of rippling or distorting the surface of the film. It has been found that drying these films in a dryer constructed in accordance with the present invention, the bafiies serve to eect circulation of the air in a manner to preclude formation of ripples and undesirable surface imperfections in the film.

While a particular embodiment of the present invention has been illustrated and described herein it is not intended to limit the invention and changes and modifications may be made therein within the scope of the following claims.

I claim:

1. Apparatus for treating material comprising an elongated generally enclosed housing, a treating chamber in `said housing, means for conveying the material along a predeterminted path through said treating chamber, treating med-ium conditioning means including air distribution means having an outlet port through which treating medium is discharged confronting the material, and baffle means including at least 011e bafiie plate extending lengthwise of said outlet port disposed angularly relative to the direct-ion of fiow of the testing medium and dividing the tiow of treating medium into at least two zones on either side of the baffle and creating a difference in the velocity and pressure of the treating medium in said zones, the treating medium diverted to one of said zones creating a suction inducing a small flow of treating medium up through the material being treated in the other zone thereby creating a slight lofting of the material in said other zone.

2. Apparatus for treating material comprising an elongated generally enclosed housing, a treating chamber in said housing, means for conveying the material along a predetermined path through said treating chamber, treating medium conditioning means including air-distribution means having an outlet port through which treating medium is discharged confronting the material, and a pair of elongated battle plates extending coextensive with said outlet port and disposed angularly relative to one another and to the direction of flow of the treating medium from said outlet port thereby dividing the flow of treating medium into three zones, two outer zones and a center zone, said treating medium diverted to said outer zones creating a suction which draws treating medium up through the material in the center zone thereby to create a slight lofting of the material.

3. Apparatus as claimed in claim 2 wherein said baffle plates opently diverge toward the material and including means for selectively adjusting the angular relationship of the plates relative to one another.

4. Apparatus for treating material comprising an elongated generally enclosed housing, a treating chamber in said housing, means for conveying the material along a predetermined path through said treating chamber, treating medium conditioning means including at least one distribution box, said distribution box having an opening at one end and being closed at its opposite end and top and side walls which taper toward said closed end and an elongated outlet port in the bottom wall thereof confronting the material whereby treating medium entering said open end is discharged through said outlet port at a substantially uniform velocity along the length of said outlet port, and baille means including at least one battle plate extending lengthwise of said outlet port disposed angularly relative to the direction of ilow of the treating medium and dividing the ow of treating medium into at least two zones on either side of the battle and creating a difference in the velocity and pressure of the treating medium in said Zones, the treating medium diverted to one of said zones creating a suction inducing a small flow of treating medium up through the material being treated in the other zone thereby creating a slight lofting of the material in said other zone.

5. Apparatus for treating material comprising an elongated generally enclosed housing, a treating chamber in said housing, conveyor means for conveying the material along a predetermined path through said treating chamber, treating medium conditioning means including a plurality of air distribution boxes extending transversely of said conveyor and spaced along the entire length thereof, each of said boxes having outlet ports confronting the material through which treating medium is discharged and bathe means including at least one baille plate extending lengthwise ot said outlet port disposed angularly relative to the direction of llow of the treating medium and dividing the ow of treating medium into at least two zones on either side of the battle and creating a difference in the velocity and pressure of the treating medium in said Zones, the treating medium diverted to one of said Zones creating a suction inducing a small ow of treating medium up through the material being treated in the other zone thereby creating a slight lofting of the material in said other zone.

6. Apparatus for treating material comprising an elongated generally. enclosed housing, a treating chamber in said housing, conveyor means for conveying the material along a predetermined path through said treating charnber, treating medium conditioning means including a plurality of air distribution boxes extending transversely of said conveyor and spaced along the entire length thereof, each of said boxes having outlet ports confronting the material through which treating medium is discharged and a pair of elongated baffle plates extending coextensive with said outlet port and disposed angularly relative to one another and to the direction of llow of the treating medium from said outlet port thereby dividing the tlow of treating medium into three zones, two outer zones and a center zone, said treating medium diverted to said outer zones creating a suction which draws treating medium up through the material in the center zone thereby to create a slight lofting of the material.

7. Apparatus for drying batts of non-woven, loosely compacted bers comprising an elongated generally enclosed housing, a drying chamber in said housing, rst conveyor means for transporting said batt through the drying chamber in one direction and second conveyor means for transporting the batt through the dryer in the opposite direction, spray means adjacent said first conveyor for applying a binder to one face of sa-id batt and second spray means adjacent said second conveyor for applying a binder to the other face of said batt, drying `medium conditioning means including a plurality of air distribution boxes disposed side by side along the length of said first and second conveyor means, each of said boxes having an outlet port through which treating medium is discharged, and bale means including at least one batile plate extending lengthwise of said outlet port disposed angularly relative to the direction of ilow of the treating medium and dividing the flow of treating medium into at least two zones on either side of the baiiie and creating a diilerence in the velocity and pressure of the treating medium in said Zones, the treating medium diverted to one of said zones Creating a suction inducing a smali iiow of treating medium up through the batt being treated in the other zone thereby creating a slight lofting of the batt in said other Zone.

8. A method for treating material` consisting of the steps of conveying material along a predetermined path through a treating Zone, treating said material by means of a treating medium directed against at least one surface Ot' said material, diverting by baie means including at least one balie plate extending lengthwise of said outlet port disposed angularly relative to the direction of low of the treating medium and dividing the ow of treating medium into at least two Zones on either side of the balile and creating a dilerence in the velocity and pressure of the treating medium in said Zones, the treating medium diverted to one of said zones creating a suction inducing a small flow of treating medium up through the material being treated in the other zone thereby creating a slight lofting of the material in said other zone.

9. A method for continuously drying material consisting of the steps of conveying the material along a predetermined path through a generally enclosed treating Zone, controlling the treating conditions by means including circulating a conditioned treating medium against the material, and disposing baie means including at least one battle plate extending lengthwise of said outlet port disposed angularly relative to the direction of llow of the treating medium and dividing the flow of treating medium into at least two zones on either side of the baille and creating a difference in the velocity and pressure of the treating medium in said zones, the treating medium diverted to one of said zones creating a suction inducing a small liow of treating medium up through the material being treated in the other zone thereby creating a slight lofting of the material in said other zone.

10. A method of continuously drying batts of nonwoven, loosely compacted libers consisting of the steps of spraying with a binder one face of the batt, conveying the batt through a generally enclosed drying zone, circulating a treating medium through the drying zone so that it is directed against the sprayed surface of said batt, spraying the other face of said batt, again conveying the batt through the drying Zone with the second face confronting the treating medium, and providing baille means including at least one bame plate extending lengthwise of said outlet port disposed angularly relative to the direction of tlow of the treating medium and dividing the flow of treating medium into at least two zones on either side of the baffle and creating a diterence in the velocity and pressure of the treating medium in said zones, the treating medium diverted to one of said zones creating a suction inducing a small flow of treating medium up through the batt being treated in the other zone thereby creating a slight lofting of the batt in said other zone.

References Cited UNITED STATES PATENTS 558,352 4/1896 Clark -l1867 X 1,419,534 6/1922 Barber 34-203 X 1,837,682 12/1931 Searight 118-67 1,912,164 5/1933 Seelig 110-71 X 1,945,851 2/1934 Freeland 118-67 2,736,107 2/1956 Dungler 34-160 2,952,078 9/1960 Litzler 34-159 X ALFRED L. LEAVlTT, Primary Examiner.

I. H. NEWSOME, Assistant Examiner.I

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