US2336698A - Loose stock drier - Google Patents

Description

Dec. 14, 1943. F. B. MORRILL LOOSE STOCK DRIER Filed Nov. 9, 1959 5 Sheets-Sheet 2 Patented Dec. 14, 1943 UNITED STATES PATENT OFFICE LOOSE STOCK DRIER Frank B. Mon-ill, North Adams, Mass., assignor to The James Hunter Machine Company, North Adams, Mass., a corporation of Massachusetts Application November 9, 1939, Serial No. 303,547 18 Claims. (Cl. 3415) The present invention relates to loose stock driers of the type in which the loose material is carried through a housing in spread-out relation on the surface of a traveling conveyor apron, while being subjected to the drying action of heated air within the housing. In these driers, it is customary to make the conveyors of foraminous or otherwise air-pervious nature, so that the heated air can be put through the layer of loose stock lying on the conveyor under moderate pressure to dry the latter rapidly throughout the entire thickness of the layer.

Since these driers are widely used to dry cotton, woolen, rayon, and other textile fibers in the loose state, it is necessary to prevent the'air current passed through the loose stock from blowing the fibers off from the sides of the conveyor and thus escaping between the lateral edges of the conveyor and the housing, as the fibers become dry and light. To prevent this escape of the fibers, resort has been had to the provision of upwardly extending baiiles or guards fixed transversely across the ends of the several perforated plates or screen sections which are linked together to form the pervious conveyor or apron, these baifles each overlapping the baiiles of the adjacent sections and thus forming a continuous low side wall at each lateral edge of the conveyor. In cooperation with this side wall, a fixed baflie has been employed, extending downward from the top of the housing or inward from the side thereof, and running for the full length of the housing, and extending down close to the surface of the conveyor on which the loose stock rests, inwardly of and in close proximity to the moving baflles on the conveyor itself. While this structure will work on wool and other heavy or coherent fibers, it will not prevent the escape of large quantities of the light, downy fibers of cut rayon or even of cotton, because it is impossible as a practical matter to make the joint between the fixed baflle and the traveling series of baffles on the conveyor air tight so as to prevent a pressure drop and consequent fiow of air therethrough. Thus, with the best attainable fit, as much as 50 pounds of cut rayon out of every 1000 pounds put through the drier will get past these guards when even the most moderate air pressure above the conveyor is used, this escap-' ing fiber clogging the fan-screens and even passing through to accumulate in the coils of the air heater, thus both wasting fan-power and creating a fire hazard; also, a large amount of escaping stock collects on the chains carrying the plates forming the conveyor, fouling the chains 68 and their sprockets and, equally obnoxious, being dumped from the chains in soiled and blackened condition into the hopper at the delivery end of the machine to become inextricably mixed with the good stock. When I have tried packing the joint between the stationary and the moving baflles with packing material such as brake lining, the more minute air p ssages which still remain permit the rayon fibers to enter but not escape, the fibers rapidly accumulating in these passages until the mass thereof distorts the opposing surfaces, bending both the stationary and the traveling bailles out of shape and even bowing and deforming the plates of the conveyor itself.

To obviate these serious drawbacks, the invention utilizes the novel principle of creating an air pressure, along the lateral edges of the conveyor or apron, which equals or slightly exceeds the air pressure over or on the stock at points on the conveyor inwardly adjacent thereto. "This condition existing, no air which has picked up fibers can pass outwardly beyond the edges of the conveyor, and thus no fibers can escape laterally from the conveyor. In other words, since it is impossible to seal the lateral margins of the conveyor into the housing inair-tight relation, the otherwise unavoidable pressure drop at the margins of the conveyor is prevented by thus supplying additional fiber-free air directly to the marginal portions of the conveyor, The resulting air pressure at the margins of the conveyor thus either produces a static condition in which there is no air-flow in either direction across the margins of the conveyor, or, preferably, produces a slight draft inwardly of the conveyor insufficient to move the fibers lying on the conveyor in proper relation and held thereto by the draft through gill; conveyor, but adequate to repel all flying The invention also includes simple and inexpensive means for obtaining the necessary supply of fiber-free air from the same air-impelling devices which produce the flow of air through the stock on the conveyor. This is accomplished by taking the air from the fans, blowers, or other air-lmpelling devices at a point where such air is at or near its maximum pressure and conducting it in a direct, short, unobstructed path to the lateral margins of the conveyor, while passing the rest of the air from such blowers through heaters and in a circuitous path, with resulting drop in pressure, before putting it through the stock and the conveyor. It also includes new means for still more completely closing the space between the conveyor edges and the housing, so as to prevent wastage of the special novel air supply utilized as described to put a reverse or back pressure on the lateral margins of the'conveyor. In its preferred embodiment this latter improvement includes the provision of a second fixed baffle mounted on the housing below the first to extend inwardly into proximity with the traveling baiiles on the conveyor, applying a strip of packing material to the edge adjacent such traveling banies, and supplying adjustable means for resiliently pressing such edge inwardly to cause the packing material to bear with the desired pressure against the outward surfaces of the traveling bailles. By arranging these two fixed baflles in spaced relation throughout both their length and their height, they constitute in effect a duct within which the required back pressure can be built up around the traveling bailles as the latter move lengthwise along such duct, thus preventing escape of the fibers over the traveling baiiies. Location of the discharge ends of the fans which force the air through the conveyor and the material thereon in proximity to the spaced fixed edges of the two bailies forming the duct provides a supply of air for the duct which is of greater pressure than that being put through the conveyor and the material.

Other objects of the invention, and the manner of their attainment, are as will be made plain hereinafter.

An illustrative embodiment of the invention is shown in the accompanying drawings, in which- Fig. 1 is a vertical transverse section of a typical apron drier for loose stock, the right-hand half of such section being omitted because identical to that shown.

Fig. 2 is an enlarged view of the parts of Fig. 1 at and adjacent one lateral margin of the conveyor, showing the improved edge-sealing features of the invention.

Fig. 3 is a plan view of a portion of one edge of the conveyor apron, showing the traveling baflles mounted thereon and the roller chain carrying the apron.

Fig. 4 is a side elevation of the parts of Fig. 3, showing in addition the fixed bailies and the surfaces on which they are mounted, and also the chain track.

Fig. 5 is a side elevation of an improved form of traveling baffle.

Fig. 6 is a side elevation of the roller chain.

The loose stock drier in which the invention is illustratively embodied is of common form, comprising an angle iron structure I supporting heatinsulating panels 3 to form an air-tight housing, within which stationary side-walls comprising longitudinally-extending upright division sheets 5 spaced inwardly from each side of the housing define a longitudinal drying chamber 1 through which the top run of a traveling apron conveyor 9 carries the stock in loose and spread-out relation while a series of air-impelling devices such as the centrifugal blower ll take air from below the top run of conveyor 9 through inlet screens l3 and discharge it upwardly through the passage l5 between division sheets 5 and the opposing walls of the housing to enter at I! over the tops of division sheets 5 into the space between these sheets, where it descends through heaters It to enter into contact with the loose stock 2| lying on the conveyor and passes through the stock and the conveyor to dry the stock, the air then entering the fans to repeat this cycle. The construction shown in Fig. 1 representing the lefthand side of the drier in vertical section is duplicated in all respects at the right-hand side thereof, hence not needing to be shown;- the vertical center plane of the machine is on line 23.

A plurality of blowers l I is employed, the blowers being located fairly close together and at the same level throughout the length of the housing and each being driven by its individual electric motor 25. A horizontal baiile 21 extends across from one division sheet 5 to the other below the fan intakes and above the bottom run of conveyor 9 throughout the housing, and suitable openings 29 are formed in division sheets 5 to fit the fan intakes 3|. The fans produce a moderate pressure difference between the air above and the air below the top run of apron 9 with its burden of loose stock, usually on the order of a pressure of 1 /2 inches of water above the stock and a vacuum of 1 inch of water below the stock and the top run. Suitable curtains (not shown) hang down at each end of the housing into proximity with the surface of the top run of apron 8,

to prevent escape of air and flying fibers over the respective feed and delivery ends of the conveyor runs. Wet stock is deposited upon the exposed feed end of the top run of conveyor 8 by a hopper feeder or any other desired means in sufficient quantity to cover the conveyor, and falls off from the exposed delivery end after its passage through the drier.

The conveyor apron is as usual in certain instances made of long narrow plates 33 having their surfaces perforated throughout and their edges turned under and rolled up as indicated at 35, Fig. 4, to impart stiffness.

In accordance with the invention, the perforated plates 33 are linked together by having their ends fastened by screws 31 to flanges 39 fixed on the side-members 4| of the links of chains 43. As shown in Fig. 2, the links are connected by headed pins 45 put through the overlapped ends of adjacent pairs of links and retained by washers and cotter pins, the pins 45 extending through bushings 41 pressed into the ends of the inner links, on which rotate V-rollers 49 equipped with anti-friction bushings 5| pressed thereinto. These rollers ride on halfround guide-rails 53 fixed by bolts 55 to the inwardly-extending flanges of angle irons 51 located at the inward faces of division sheets 5 and suitably bolted to the uprights l on which division sheets 5 are mounted. Both the upper and lower runs of the chain at each side of the conveyor are thus guided by V-rollers and rails, so that the lateral margins of the apron are guided accurately in straight lines without liability of lateral deviation. At the ends of their runs, namely at the feed and delivery ends of the conveyor, the rails 53 and the angle irons 51 terminate, and the chains are carried around sprockets (not shown) engaging in the open portions of the links in usual manner.

Each end of each plate 33 is provided with an upstanding guard or baffle 59 attached thereto, herein by putting the screws 31 through holes in the angularly-bent foot of the guard, and a stationary guard or baffle Si i applied to the interior surface of division sheet 5 throughout the length of the housing to overhang and shield the series of guards 59 almost down to the surfaces Of plates 33, both substantially as usual heretofore. In accordance with the invention, however, no attempt is made to close the space between the movable guards 59 on the plates of the apronand the stationary guard or baffle 6| fixed to the housing, but instead a rather generous space for the travel of air is purposely left between the proximate surfaces of these opposed parts. Then a third guard-member orbaflle 68, coextensive in its extent lengthwise of the housing with guard BI, is likewise fixed to the inward surface of each division sheet 5, below stationary guard 6i, with all portions amply spaced from guard 6| to leave an air passage 65 between them. The free lower edge of guard 63 terminates well above the foot of the movable guards 59 traveling with the apron, outwardly of such movable guards, and as shown in Figs. 1 and 2 is equipped with a strip 61 of suitable packin material such as brake lining affixed to its surface which is toward the moving guards 59. This free edge of guard 63 is bent to form stiffening ribs 69, and in the channel between such ribs stand the ends of expandin coil springs ll located at frequent spaced intervals in the length of the housing. These springs are equipped with discs 13 welded to their inward ends and taking bearing against the free edge-portion of guard 63, and each spring is mounted on the reduced shank of an adjusting screw threaded through a nut ll welded to the inward face of division sheet 5 and maintained in adjusted position by lock-nut "I9. The shoulder on each adjusting screw carries a washer 8|, so that by turning the screw in or out the degree of pressure of the spring against the free edge-portion of guard 63 can be varied, and thus the degree of pressure of packing material 61 against the outward surface of the procession of guards 59 moving along and in contact with the packing material can be varied. All that is desired is the closing of the gap between the lower edge of guards 63 and the moving guards 59 to make the injected air pass between the latter and guard 61, but owing to unavoidable wear and tear on the guards in use it is sometimes desirable to apply sufiicient pressure to divert those guards which have been prung outward, back toward the center line of the machine, in order to make contact with the rest of the guards 59 and thus close the space between them and guard 63.

In order to enable the movable guards 59 to present a substantially continuous outward surface to contact with the packing 61, while still making possible the overlapping of each guard 59 with its adjacent guards at each end, as is necessary on these aprons, the left-hand end of each guard 59 is ofiset inwardly over an area slightly exceeding the overlap thereonto of the adjacent guard 59, the terminal line and shape of this offset portion being indicated at 83 in Figs. 4 and 5. Thus the exposed portions of the outward surfaces of the successive guards 59 at each lateral edge of the apron lie all in the same plane, and the contact therewith of the packing material is broken only for very short intervals at the end of the overlap.

To supply air to the passage 65 between the two stationary guards GI, 63, at a pressure preventing air-flow from the drying chamber I outwardly under the bottom edge of guard 6|, the division sheets 5 are cut away either at frequent intervals or throughout the length of the machine to form apertures 85 between the respective lines or areas of attachment of the fixed edges of these guards. By locating these air-ports 85 directly above the level of the discharge outlets 81 of the casings of the blowers I I, air is taken from these blowers while it is at the highest pressure created thereby, and through being conducted in a shortpath by the duct defined by guards 6 i, 63, to the lateral margins of the apron 9 arrives there at a slightly greater pressure than th air that is forced to travel upwardly through the recirculation passage i5, which extends upward at each side of the machine outside of division sheets 5 for the entire length of the drier, thence over the top of division sheets 5, and downthrough the heaters i9-in a devious path to enter drying chamber 1 and make contact with the material 2| being dried. By this arrangement, all airflow outwardly at the lateral marginsof apron 9 and upwardly over the inward faces of movable uards 59 is prevented, because owing to the superior air pressure in the duct over that created at the bottom edge of stationary guard 6| by the drying air put down through the heaters there is either a static condition in which air how inward under the bottom edge of guard 6| is checked by the air pressure across and through the stock plus the damming effect of the stock packed against the bottom portion of guard 6|, 'or else there is a slight inward flow of air which passes under the bottom edge of stationary guard Bi and thence down through the apron via the outermost perforations in the plates thereof. As shown in Fig. 3, these perforations begin practically at the bottom edge of the guard GI, and thus there is no significant tendency 01 the air flowing through the duct to disturb the stock and crowd it inwardly so as to increase the thickness of the layer on the apron and thus retard the drying, since the draft down through the apron across the rest of its width holds the stock securely in place on the apron, and thus the stock cannot be blown far inward.

As is obvious, it is impossible for any flying fibers of stock, however, light and downy, to make any excursion outwardly off from the lateral edges of the conveyor, because to do so they must ascend the inward surface of the series of moving guards 59, and this is impossible in the face of the static or downwardly flowing air thus provided at such surface. The function of the packing material 61 is not to attempt to create an air-tight seal between the fixed parts of the housing, the division sheets 5 and guards 63, but merely to insure that the air put into the air-passage 65 will not escape down the outward side of moving guards 59 in sufficient quantity to let the pressure in the duct down to a point where air from the drying chamber 1 can get over guards 59 or between the overlapping ends thereof to introduce flying fibers into the spaces where the chains travel. Since the air delivered by the blowers has been cleared of flying fibers both by the screening action of the perforated apron and by the screens l3 over the fan intakes, and since this fiber-free air alone reaches the moving guards 59 and the packing material 61, all possibility of lateral escape of the fibers, of fouling of the chains thereby, and of accumulation on and between the fixed and moving guards with resulting clogging and injury thereto, is eliminated. The moving guards 59 no longer serve as mechanical obstacles to lateral escape of the stock, but merely act to guide the special stream of fiber-free air and to help maintain this air at the desired pressure equalling or exceeding that in the drying chamber 1.

Because of the accuracy with which the chains 43 and hence the lateral margins of apron 9 are guided by the improved construction of the chains and trackways therefor, and because with occasional attention each successive guard orv baiiie II of the series can be made to travel in exactly the same path as its preceding guard when distortion through accumulation of fibers is eliminated, the packing material 81 can be eliminated in certain cases. This is done by merely setting the free lower edge of guard I! close enough to the outward surface of the series of moving guards 50 by adjustment of screws ll so that the clearance between these fixed and moving guards will be close enough to retain the desired air pressure at the inward surfaces of moving guards 59. Ordinarily, a clearance of ,4; inch between the opposing surfaces of guards 63 and it proves sufficient for this purpose.

Where air blasts of different pressures exist at different points in the length of the conveyor, as where special Jets of higher pressure are projected up through the apron to turn over or agitate the stock in order to facilitate its drying, the same basic principle of the invention is applied to prevent lateral escape of fibers from the apron, the pressure in the ducts in which the moving baiiles 59 travel being increased locally for a commensurate distance along the apron to ensure a pressure in the ducts equalling or slightly exceeding that which is being applied to the stock across the width of the apron at such locality. Air is either led directly from the high pressure blowers to the ducts, or else special blowers are provided at these points to supply an equal or superior air pressure to the ducts.

While I have illustrated and described certain forms in which the invention may be em- :bodied, I am aware that many modifications may be made therein by any person skilled in the art, without departing from the scope of the invention as expressed in the claims. Therefore, I do not wish to be limited to the particular forms shown, or to the details of construction thereof, but

What I do claim is:

1. In a drier, in combination, a traveling conveyor for the material to be dried, means forcing air through the conveyor and the material carried thereby, and means directing a separate airblast downwardly and inwardly against the material-bearing surface of the conveyor at the lateral edge of the conveyor so as to prevent diversion of the material off from the lateral edge portions of the conveyor by the first-named air.

2. In a drier, in combination, a traveling conveyor for the material to be dried, means forcing air through the conveyor and the material carried thereby, and means preventing such air from diverting the material laterally off from the conveyor, including means directing a separate blast of air against the lateral margin of the conveyor.

3. In a drier, in combination, a. traveling conveyor for the material to be dried, means forcing air through the conveyor and the material carried thereby, and means creating a. zone of air-pressure against the upper surfaces of the lateral margins of the conveyor at least equal to that existing over the intermediate portions of the width of the conveyor.

4. In a drier, in combination, a traveling conveyor for the material to be dried, means passing air through the conveyor and through the material carried thereby, and means producing aircurrents against the lateral margins of the conveyor to blow the material in contact with the lateral portions of the conveyor inwardly away from the lateral margins of the conveyor.

5. In a drier for loose material, in combination, a housing, a conveyor therein on which the loose assaees material rests, means creating a greater air-pressure above the conveyor and material thereon thanexists below th conveyor surface carrying the material, and means creating a counter airpressure against the lateral edges of the conveyor preventing passage of air in contact with the loose material off from the lateral edges of the conveyor.

6. In a drier for loose material, in combination, a housing, a traveling conveyor therein for the material to be dried, stationary side walls flanking the conveyor, means passing air through the material carried by the conveyor and then through the conveyor itself, and means supplying air free from portions of the loose material to the space between the side walls and the lateral edges of the conveyor in excess of the amount of air which can pass through such space.

'7. In a drier for loose material, in combination, a housing, a traveling conveyor therein on which the loose material rests, stationary side walls at each side of the conveyor, stationary guard means at the lateral margins of the conveyor to retain the materials on the conveyor, means passing air through the conveyor and through the material resting thereon, and means creating airpressure against that portion of the conveyors surface lying between the guard means and the side walls at least equalling the air pressure at the surface of the guard that is presented toward the loose material.

8. In a drier for loose material, in combination, a housing, a conveyor traveling therein on which the loose material rests, imperforate and impervious baflies fixed to the housing and overhanging the lateral margins of the conveyor, means passing air through the conveyor and through the material resting thereon, and means creating an air-pressure at the outward surfaces of the overhanging portions of the battles at least equalling that existing over the intervening portions of the width of the conveyor.

9. In a drier for loose material, in combination, a housing, a conveyor traveling therein on which the loose material rests, baflle s fixed to the housing and overhanging the lateral margins of the conveyor, means passing air through the conveyor and through the material resting thereon, moving bailles fixed to the lateral margins of the conveyor outside the fixed baffles, and means creating an air-pressure in the space between the fixed and moving baflles which at least equals the air-pressure at the inward faces of the fixed baffles.

10. In a drier, in combination, a housing, an air-pervious apron traveling therethrough and carrying the material to be dried, upwardly extending bailies on the lateral edges of the apron, baifles fixed on the housing and hanging down inwardly of the first baflies ,and in overlapping relation thereto, means forcihg air down through the apron and the material, ereon, and means creating an air-pressure in the space between the haflies on the apron and those on the housing preventing entrance thereinto of air from over the apron.

11. In a drier, in combination, a housing an air-pervious apron traveling therethrough and carrying the material to be dried, upwardly extending bailies on the lateral edges of the apron, bailles fixed on the housing and hanging down respectively inwardly and outwardly of the first bailles in overlapping relation thereto, packing means substantially closing the space between the baffles on the apron and the outward baflies on the housing, means forcing air down through the apron and the material thereon, and means creating an air-pressure in the space between the apron baiiles and those on the housing preventing entrance thereinto of air from over the apron.

12. In a drier, in combination, a housing, an air-pervious apron traveling therethrough and carrying the material to be dried, a fan forcing air through the apron and the material thereon, and a duct having its-discharge end in proximity with the lateral edge of the material-supporting surface of the apron and prolonged along such edge, the duct receiving a supply of air under pressure from the tan and discharging such air against the surface of the lateral edge to flow inwardly of the apron and through the apron but not outwardly of the apron around the lateral edge.

13. A drier according to claim 12, in which the apron has bafiie means extending upwardly from its lateral margin into the duct.

14. A drier according to claim 12, in which the apron has baflie means extending upwardly from its lateral margin into the duct, and in sliding contact with the outward wall of the discharge end of the duct.

15. In a loose stock drier, in combination, a housing, a conveyor traveling therein on which the loose stock rests, a heater, means impelling air through the heater and then through the stock on the conveyor, and means discharging other air from the impelling means against the lateral margins only of the conveyor before pass ing through the loose stock.

16. In a loose stock drier, in combination, a housing, division sheets within the housing defining a passage therethrough, an air-pervious conveyor stretching across and traveling through the passage and carrying the stock on its upper surface, heaters, air-impelling devices taking air from within the passage at points below the conveyor and discharging it upward outside the division sheets, through the heaters, and down through the conveyor and the stock thereon, and ducts passing air from the impelling devices through the division sheets onto the lateral margins of the conveyor before such air makes contact with the stock.

17. In a loose stock drier, in combination, a housing, an apron carrying the loose stock therethrough, means forcing air down through the apron and the stock thereon, upstanding bailles on the lateral margins of the apron, bailie means fixed on the housing inwardly overhanging the upstanding baflies, other baflie'means fixedon the housing overlapping the upstanding baflles outwardly of the latter, and means adjusting the outward bafiles toward and from the upstanding battles on the apron.

18. The method of preventing lateral escape or loose stock .rom a pervious apron when air is forced down through the apron and the stock lying thereon, which comprises building up an air-pressure at such lateral margins equalling or exceeding the air-pressure over the apron at ad- Jacent points located inwardly of the margins.

FRANK B. MORRILL.

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