US3521375A - Dryer - Google Patents

Description

July 21, 1970 D. c. SANDERS. JR 3,521,375

DRYER Filed May 16. 1968 4 Sheets-Sheet 1 FIG.!

| I I8 INVENTOR.

I DEWEY c. SANDERS,JR.

l /fiTfiTIEY July 21, 1970 -D. c. SANDERSLJR 2 v DRYER Filed May 16. 1968 V 4 Sheets-Sheet 2 INVENTOR. DEWEY C. SANDERS,JR.

I W :izxzzv July 21; 1970 D; c. SANDERS. JR 3,521,375

DRYER Filed may 16. 1968 4 Sheets-Sheet 5 I v:; m I ""1 I, I II V I I INVENTOR.

L B L FIG. 5

DEWEY G. SANDERS,JR.

July 21, 1970 D. c. SANDERS. JR

DRYER 4 Sheets-Sheet 4 Filed May 16. 1968 FIG. 6"

- YNVENTOR. DEWEY C. SANDERS, JR.

/ A TQRNQ FIG. '7

United States Patent Office Patented July 21, 1970 US. Cl. 34-44 7 Claims ABSTRACT OF THE DISCLOSURE Drying apparatus for drying fibers in yarn or fabric as a continuous length element, and more particularly a drying apparatus in a machine for impregnating such fiber with a liquid fiber-to-rubber adhesive coating in the manufacture of tires, belting and similar products, wherein the element is rapidly dried at a controlled temperature by flame generated infra-red type heating means while moving a gas stream rapidly over the surface of the element and protecting the heating means by a shielding means from the flowing gas stream against any adverse effect on the infra-red radiation from the heating means.

BACKGROUND AND SUMMARY OF THE INVENTION This invention relates to dryers, and more particularly to dryers for fibers (whether in yarn, cord, fabric, etc. form), especially such fibers to be used in the manufacture of tires, belting and other rubber products.

The rubber products industry uses various fibers for reinforcement, including rayon, nylon, polyester, fiber glass, etc. and may use now or hereafter other natural and artificial fibers. The term fiber, unless otherwise modified, is intended to be used in its generic sense to include all of these fibers. This machine is adapted to process by dipping and drying any continuous length element, such as a woven fabric made up of cord formed of fibers, a yarn made up of fibers before being twisted into cord and woven into fabric, etc. Dipping the yarn is usually done where application of the adhesive over the entire surface of the fiber is desired, such as with fiber glass; while other fibers are dipped in the fabric form. Therefore, the terms continuous length fiber element, continuous length element, fiber element" or element used herein, unless otherwise modified, are each intended to cover any continuous length yarn, cord or fabric since each is composed of fibers. The term fabric unless otherwise modified, is intended to cover any suitable fabric, including square-woven fabric and including so-called cord fabric used for tires and having a fairly open and loose weave wherein the cords form the warp and a comparatively small number of fill threads connect the cords solely to facilitate handling.

It is well known that before any such element made of textile material can be incorporated into rubber articles, especially those to be subjected to drastic conditions of flexing or bending, the fibers thereof must be prepared by coating or impregnating with an adhesive that will bond well to both rubber and the fibers. These adhesives are dispersed, dissolved or suspended in a liquid vehicle, generally water, into which the element is dipped and subsequently dried.

Such elements have been dried by blowing hot air through a drying oven in a relatively low temperature. Because of the low drying temperature and the attendant low speed of operation, large capacity drying ovens have been necessary so as to require vast expenditures of capital andlarge factory areas for operation. It has been recognized that if such elements could be dried more rapidly, but at a controlled temperature to prevent deterioration of the fiber, the speed of drying could be vastly increased, or the size and capacity of the drying apparatus could be considerably reduced.

This invention is an improvement on the invention disclosed in the T. M. Kersker et al. US. Pat. No. 3,250,641, granted May 10, 1966, and entitled Method of Processing Tire Cords, Tire Cord Fabric, And The Like wherein infra-red radiation is used to speed up the drying and many of the problems in such element processing for rubber goods manufacture are explained in some detail to which reference may be had if desired. The dryer must be of sufficient size to dry the adhesive liquid coating sufficiently so that the coating will not be picked off or ruptured by the support means engaged following the drying step.

This invention is also an improvement on the co-pending US. patent application Ser. No. 729,282 entitled.Dryer or Heater filed May 15, 1968 by Grover W. Rye and Alexander V. Alexeff by the addition of a burner flame shielding means to this type dryer with suitable modification of the gas flow, and the disclosure of that application is incorporated herein by this reference thereto.

- The present invention relates to an apparatus for drying such continuous length element in a machine for impregnating such element with a liquid fiber-to-rubber adhesive in a coating in the manufacture of tires, belting and other rubber products, wherein the element is rapidly dried at a controlled temperature by flame-generated infra-red type heating means while moving a gas stream rapidly over the surface of the element and protecting the heating means by a shielding means from the flowing gas against any adverse effect on the infra-red radiation from the heating means.

An object of the present invention is to provide an apparatus for rapidly and uniformly drying a fiber containing element at a controlled temperature so as to manufacture a maximum quality article by minimum sized equipment.

Another object of the present invention is to provide a method of drying fibers at a very high temperature and speed without detriment to the fibers or any coating thereon.

These and other objects of the present invention will become more fully apparent by reference to the appended claims as the following detailed description proceeds in reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings,

FIG. 1 is an elevational schematic vertical view, partially in section, of a machine or apparatus for coating such element and subsequently drying the coating in a drying tower;

FIG. 2 is a side elevational view of two of the drying apparatuses located within the drying tower, having some parts omitted or cut away, and having opposed heating zones sandwiching therebetween opposite faces of the element;

FIG. 3 is a top plan view, taken generally along the line 3-3 in FIG. 2, and showing only the element and the gas moving means for discharging the gas streams into and through the heating zones and subsequently discharging it from the apparatuses in FIG. 2;

FIG. 4 is a perspective view by the fabric of one of the heating apparatuses in FIG. 2 with some parts omitted or cut away for clarity;

FIG. 5 is a horizontal sectional view, taken generally along the line 55 in FIG. 4, through the discharge nozzle and showing its adjustable flow control gate means;

FIG. 6 is an enlarged, schematic, side elevational view with parts omitted or cut away showing the infra-red heating and gas stream action on the element and certain selected parts in FIG. 2;

FIG. 7 is an electrical and fluid flow diagram of the solenoid gas valve controlled main burner gas line to the infra-red burners, a valve controlled flow diagram of the fluid system for the burner panel retracting cylinder and gas fiow damper cylinder, and the electrical circiut for controlling the solenoids operating these valves in response to the travel speed of the processed element; and

FIG. 8 is a top plan view taken generally along the line 8-8 in FIG. 2 of the gas stream flow duct, infrared panels and reflector means surrounding the element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 of the drawings shows machine 10 for treating continuous length fiber element 12 by applying adhesive thereto and subsequently drying the adhesive with machine 10 including drying tower 14 (taking the form of either a separate tower or one zone of an element processing building) having structural members 14a supporting sixteen substantially identical drying apparatuses or dryers 16, to be described in more detail hereinafter.

Although machine 10 can be used for treating any suitable fiber element 12 (such as yarn, cord or fabric), a woven fabric will be specifically used hereafter in this description with this fabric having a length dimension L along its direction of movement T by drive rolls 22, 23 and 24; a width dimension W transverse thereto; and opposite, generally parallel faces F1 and F2.

Since each apparatus 16 is especially adapted for driving moisture out of fibers or fabric, it should be apparent that it has many other uses, such as driving moisture out of woven fabric before calendering in the manufacture of rubber goods.

Machine 10 in FIG. 1 sequentially moves fiber element 12 in travel direction T from feed roll 21 through coating means 18, through drying tower 14 having sixteen drying apparatuses 16 with each having infra-red heating means 28, over drive roll or support means 24 with fiber element 12 freely supported between drive rolls 23 and 24 from the bottom or inlet to the heating zones 40 provided by drying tower 14, and onto wind-up roll 25 or to subsequent heat treating and/ or other processing equipment.

Coating means 18 includes tank 20 containing any well-known fiber-to-rubber adhesive 19 dissolved, dispersed, or suspended in a liquid vehicle. Such adhesive is generally based on resorcinol-formaldehyde resins and latex in a aqueous medium.

Suitable drive means is provided for relatively moving element 12 through machine 10' comprising coating means 18 and drying tower 14. This drive means takes the form herein of suitable tensioning or support rolls 22, 23 and 24 with any one or all driven by a suitable motor driven drive or independent motors to advance element 12, through machine 10 and to apply suitable tension to element 12. When fabric element 12 has a width W of about 60 inches, 2,000-25,000 pounds tension thereon will be the operating range for different fibers, and this tension is used for further processing thereof after the adhesive has been dried and for maintaining the fabric taut and planar against lateral deflection and flapping by gas streams 42 mentioned hereafter.

Element 12 is freely supported in drying tower 14 so that the coating thereon will not be damaged during the drying thereof. There must be sufficient drying capacity in tower 14 to dry the liquid coating sufiiciently so that the coating will not be picked off or ruptured by support roll 24. Hence, it is preferable not to use a drum-type dryer or any other type cylindrical supports in the heating zones 40 because they will tend to pull off the adhesive covering. Also, an air cushion cannot be used to suitably support cord fabric on such drum or roller since the air would quickly penetrate any open weave of the fabric and the 25,000 pounds maximum tension would quickly bring the fabric into contact with the cylindrical surface.

It has been found in practice that drying apparatus 16 in tower 14 manufactures maximum quality element 12 with minimum equipment size.

Machine 10 has a plurality of drying apparatuses 16 therein for drying the fibers in the yarn or fabric in continuous length element 12. These are arranged in eight tiers T1T8, and in two banks B1 and B2 so that each of sixteen apparatuses 16 therein may be identified as to location, as to tier and bank, such as the apparatus in the lower lefthand corner of FIG. 1 being identified as drying apparatus 16 in tier T1, bank B1. Apparatuses 16 in each bank are arranged in series along the length of the fabric in the tiers while any two horizontal apparatuses 16 in opposite banks B1 and B2 and in the same tier are arranged on opposite sides of fabric element 12 as it passes through drying tower 14. Apparatus 16 in each tier and bank has a width wider than fabric element 12, as shown in FIGS. 3, 4 and 8, to provide a proper drying action as will be brought out in more detail hereinafter.

DRYING APPARATUS 16 The remainder of this application will be directed toward the specific structure, mode of operation and advantages of each substantially identical drying apparatus 16 considered either alone or in any tier or bank combination. The explanation hereinafter of drying appara tus 16 will emphasize the details in apparatus 16 in tier T2, bank B1 even though all sixteen apparatuses 16 in FIG. 1 are identical in construction except the two apparatuses in each tier have some common operating parts (see FIGS. 2, 3 and 8) and the apparatuses in bank B1 are substantially mirrOr images of those in bank B2. Then, the structure and mode of operation common to the two horizontally aligned apparatuses 16 in tier T2 for both banks B1 and B2 will be described; later, the eight series arranged and vertically aligned apparatuses 16 in tiers T1-T8 in bank B1 will be described.

For reference herein a typical operating example of apparatus 16 will be given now. It has been found that an actual operating drying apparatus 16 operates satisfactorily with approximately the following dimensions and operating characteristics (herein referred to as Table I):

' Fabric element 12:

Water picked up was equal to weight of fabric. Tension 2,00025,000 pounds.

Air, F 164 Approximate dimensions within frame 30 of burner panel 31 for burners 32 and spacer blocks 33:

Height 4' Width 5 6" Discharge nozzle 50:

Dimensions 50W 1 /2" Dimension 50L 5 9" Without Screen 64 With Screen 64 Discharged air velocity (Feet per minute) 4, 000-5, 000 Air discharged quantity:

C2210 feet per minute output of fan 1 Maximum.

Temperatures at downstream side of drying apparatus 16 at exhaust nozzle 56 at top of apparatus 16 With Screen Without Screen 64 64 Each drying apparatus 16 includes heating means 28, preferably of an infra-red emitting or radiating type, for drying element 12. Although heating means 28 may use any suitable infra-red source, such as an electric quartz tube heating element, etc., it is preferred to use herein an infra-red heater 32 having a fluid (preferably natural gas) fired flame for generating infra-red radiation because of its economy of operation, rapid cooling, efiicient heat transfer, and desirable radiating characteristics. One suitable form of heater 32 is that disclosed in US. Pat. No. 2,775,294 granted Dec. 25, 1956 to G. Schwank and entitled Radiation Burners wherein a gas-air mixture burns on the outer surface of plate 7 in that patent to heat it to incandescence causing this surface to emit infrared radiation then striking and heating element 12. Such burner 32 has a metal screen mounted about inch from this radiant surface, extending parallel thereto, and being substantially coextensive with this surface serving as a red-radiating screen to increase the burner efiiciency and to assist in providing a uniform distribution of infrared radiatnt energy in the manner well known in the art. Then, combustible gas mixed with air burns so that the outer radiating surface of plate 7 has a visibly radiant temperature of approximately 1300 F.1600 F. with the radiation intensified by the re-radiating screen.

Heating means 28 includes infra-red heating panel 31 in FIG. 4 having spacer blocks 33 and heaters 32 (shown schematically by diagonal lines in FIG. 4) arranged in a checkerboard-type pattern within its frame 30 to provide a planar, radiating face on panel 31 parallel to and facing element 12 surface F1.

The intensity and pattern of radiation desired may be varied. Since the intensity of radiation generally varies inversely as the square of the distance between the objects since one considers a point source of radiation radiating out over the entire interior surface of a surrounding sphere, it would be logical to assume that changing the distance between the radiating face of panel 31 and element surface F1 would be the desirable way of changing the intensity of radiation on surface F1. This is not true here since the radiating face of panel 31 is not a point radiating source but is approximately parallel and coextensive with surface F1 in heating zone 40. Hence, radiation intensity is not effected by the distance between the radiant face of panel 31 and element surface F1. Even the radiation that might normally escape outwardly horizontally in the space between panel 31 and face F1 is held between their parallel faces and reflected back onto fabric element face F1 by reflector plates 90, which will be described in more detail hereinafter. Therefore, the desirable way to change the intensity and pattern of radiation desired is to change the number of heaters 32 and the number of spacer blocks 33 located within frame 30 of panel 31 and to change their distribution within frame 30.

Each heater 32 and panel 31 is fed by gas main line 34 in FIGS. l and 2. Gas entering drying tower 14 through gas main line 34 travels in FIG. 2 either: (1) through solenoid gas valve 35 to be mixed with air by air mixer 35a before going through main burner gas line 37 into vertically extending manifold 37a on the back of panel 31 having flexible hoses 39, one leading from manifold 37a to each infra-red burner 32, or (2) through pilot gas line 36 to the burners on the radiant face of panel 31. Any suitable conventional igniter and safety features are provided. Each gas line 36 and 37 has pivotal connections 38 therein adapted to permit pivoting of the line components about a horizontal axis during horizontal movement of radiant heating panels 31 between solid and dot-dash line positions in FIGS. 2 and 6, as will be described in more detail hereinafter.

Each infra-red heating panel 31 heats an infra-red heating zone 40 on the outer surface of element 12, such as on face F1 or F2, and the desired action in each heating zone 40 is to rapidly and uniformly dry fabric element 12 at a controlled temperature. This action is obtained in the present disclosure by rapidly and uniformly evaporating the moisture by the infra-red radiation from panel 31, and by rapidly and uniformly removing by mass transfer the evaporated liquid molecules and heat from fabric element 12 in this heating zone 40 by drying apparatus 16. The following paragraphs will explore this mode of operation more carefully and more specifically.

Infra-red radiation from burner 32 is an efiicient method of heat transfer to provide the energy necessary to evaporate the water into its vapor form and is much better than many other type high temperature heating sources. Infra-red waves extend over the spectrum in wave length from 0.8 to 300 microns from the near infra-red to the far infra-red range. There is a broad absorption band for water, several microns wide, about at 3.0 microns wave length in the near infra-red region where water is evaporated most quickly and most efficiently. The aforementioned Schwank-type infra-red burner 32 emits strong radiation in this absorption band for water vapor for efliciently and rapidly vaporizing the water or aqueous molecules in the coating. The moisture within the fibers and adhesive coating is heated and evaporated within the time period necessary to dry the adhesive coating on the surface of the fibers while still permitting the moisture to escape therefrom before the outer surface of the adhesive is dried and/or cured sufiiciently to form a skin or crust entrapping the remaining moisture.

Any suitable gas may be used, but air is specifically used herein even though the generic term gas is used wherever appropriate since any suitable gas may be used. A gas moving means moves gas stream 42 with respect to outer surface P1 of element 12 through heating zone 40 during infra-red heating thereof for scrubbing this surface F1 and removing by mass transfer aqueous vapor molecules so as to rapidly dry element 12 at a controlled temperature. Stream 42 is a rapidly flowing river of gas blowing at surface F1 and traveling along surface F1 being dried by the infra-red. With fabric element 12 saturated with water based chemicals 19, a fast rate of drying of element 12 to remove the water is highly desirable. Fast drying results in minimum equipment size, improved control of drying conditions, and improved quality of element 12. The evaporated liquid molecules carried away by stream 42 include, of course, not only water molecules but molecules of any volatile material.

The rate of drying is increased by removal of liquid molecules from surface F1 to allow better penetration of infra-red energy and by the eflicient mass transfer of water molecules to the gas by a scrubbing or vacuuming action of surface F1 by flowing stream 42. Flowing stream 42 also removes convectional heat from drying zone 40 and from fabric element 12 so as to provide a rigid control of the temperature of the fabric element so that it will not exceed the safe limit. The gas in stream 42 is cool enough to cool element 12 as it passes across it. This is a peculiar problem to a fabric, such as nylon, some types of which might be damaged if the temperature exceeded 250 F. Not all objects dried require this close temperature control by cooling; for example, ceramics, painted metal parts, etc. preferably pick up as much of heat as possible and cooling is not desired since cooling is a detriment to eflicient operation. It should be apparent that velocity of stream 42 will effect the extent of scrubbing action and rate of drying overall quantity of air flowing in stream 42 will effect both rate of drying and heat removal. Preferred condition of the gas in stream 42 is a relatively dry and cool gas, such as air at ambient conditions. The cool gas will have a greater capacity for heat pickup, and the dry gas will pick up the moisture and other evaporated molecules more quickly and is more transparent to infra-red radiation from panel 31. Moisture laden gas interferes with the transmission of infra-red rays (because it absorbs this infra-red radiant energy) and interferes with eflicient drying and heat transfer. Therefore, if gas stream 42 is heavily laden with moisture, it may substantially prevent transmission of the infra-red rays from panel 31 to surface F1 and may serve as an insulating layer over surface F1 to prevent removal of heat and water vapor. Hence, recirculation of the gas in stream 42 would not be desirable because it would be hotter than desired so could not pick up more heat and could not cool element 12, and might well be saturated with evaporated molecules, such as water molecules, which would interfere with infra-red transmission and pickup of evaporated water molecules. Hence, gas stream 42 permits infra-red heaters 32 to operate at their most eflicient temperature, is located as close as possible to fabric face F1 for fast drying, and still permits accurately controlling the surface temperature of element 12 to prevent damage thereto. Note that the infra-red radiation from heaters 32 strikes heating zone 40 to provide drying at the same time as gas stream 42 scrubs the heating zone. This action provides most rapid drying with minimum size equipment.

The aforesaid gas moving means includes gas discharge means for directing gas stream 42 as a gas layer or gas curtain generally along and over surface F1 in heating zone 40 to provide the aforedescribed scrubbing action. Since air of the condition described in the preceding paragraph is preferred, relatively cool, dry air at ambient conditions is drawn in through inlet duct 46 in FIGS. 1, 2 and 3 (shown schematically in FIG. 1 as two inlet ducts 46 for each tier for simplicity of illustration instead of the single inlet duct 46 in FIGS. 2 and 3) by motor driven, discharge, fresh air or inlet fan 44 in FIG. 3 to be forced through nozzle duct 48 and out nozzles 50 in FIG. 2 to form two gas streams 42. Each gas discharge nozzle 50 is a rectangular outlet having its length 50L in FIGS. 4 and 5 many times greater than its width 50W. Nozzle 50 also has mounted on duct 48 by screws 53 adjustable cutoff plate 52 and has mounted on duct 48 deflector 54 described in more detail hereinafter.

Discharge nozzle 50 is preferably mounted so that length dimension 50L is generally parallel to surface F1 of element 12 in heating zone 40 and width dimension 50W is generally perpendicular to surface F1 with nozzle 50 directing its discharged gas generally along surface F1 in heating zone 40 from the lower edge of this heating zone. It should be apparent that scrubbing action and heat removal will be obtained by having the discharged stream from nozzle 50 directed transversely across,

longitudinally with (in co-current flow), or longitudinally against (in contraflow) travel direction T of element 12 Directing stream 42 across travel direction T (across element 12 width W) would not be desirable because stream 42 would not uniformly hit each portion of width W of fabric element 12 so that the fabric would not be uniformly processed across its width. Nozzle 50' may be mounted near one edge of heating zone 40 with its length dimension 50L generally parallel to width dimension W of fabric element 12 with air stream 42 directed in heating zone 40 generally along the length of movement T of element 12 either in the same direction (in co-current flow) or the opposite direction (in contraflow) to the movement T for generally uniformly removing liquid molecules over width W of element 12 to give width W uniform processing. Although stream 42 directed opposite to the direction of travel T (in contraflow) would give an effective scrubbing action, it has been found desirable to mount nozzle 50 at the bottom of heating zone-40, as shown in FIGS. 4 and 6, so that gas stream 42 is directed in direction T of element 12 (in co-ourrent flow) with this direction being upward so that the natural convection will help move gas stream 42 toward gas exhaust vent 56.

Nozzle length dimension 50L should be at least as wide as width dimension W of fabric element 12 so that gas stream 42 will uniformly effect each increment of the fabric across its width as it travels in direction T. Dimension 50L should be preferably greater than fabric width W so that the lower velocity components in gas stream 42 emerging from the lengthwise ends of nozzle 50 do not travel across surface F1 and a more uniform velocity layer of gas in stream 42 travels along the length of element 12.

It is desirable to provide a generally uniform quantity of gas flowing over each portion of fabric element width W in heating zone 40 for generally uniformly removing the liquid molecules across this width W and for maintaining a generally uniform temperature across fabric element width W in heating zone 40 since drying and heat removal are directly proportional to the quantity of gas flowing in stream 42 and since the scrubbing action is proportional to the velocity of flowing stream 42. This uniform distribution of gas across width W may be obtained either by carefully designing nozzle 50 and maintaining its width 50W constant while providing certain desirable gas turning vanes and baffles within nozzle duct 48 and closely adjacent nozzle 50 to control the distribution of gas flow to nozzle 50, or by making nozzle 50 adjustable.

Nozzle '50 may be made adjustable by providing in FIG. 5 cutoff plate '52 mounted by screws 53' in elongated parallel slots in the wall of duct 48 to serve as an adjustable flow control gate means with its flow controlling edge 52a intercepting the flow through gas dis charge nozzle 50. Pivoting plate 52 permits increasing or decreasing the quantity of gas flowing through either end of nozzle 50 so as to obtain uniform quantity of gas flow over element width W. However, since edge 52a acts like a sharp edged orifice to laterally disperse stream 42, after it emerges from nozzle 50, to strike the radiating faces of burners 32 to provide disadvantages mentioned in more detail hereinafter, it is preferable to have nozzle 50 discharge a closely held together jet-like stream 42 as a thin layer of gas traveling over face F1 by originally designing nozzle 50 to provide this condition. Suitable gas turning vanes, baffles and tubular extension of nozzle '50 into nozzle duct 48 are desirable to prevent this lateral dispersion.

It is desirable to have gas stream 42 directed toward surface F1 to increase the scrubbing action and heat transfer action. This may be done by so directing nozzle 50 or by adding gas stream deflector 54 mounted on gas over and along surface F1 but also toward and against surface F1, as seen by the arrows in FIG. 4, to serve with nozzle 50 as a gas discharge directing means. Directing gas stream 42 toward and causing it to impinge against surface F1 has the advantage of increasing the scrubbing and heat transfer action when stream 42 strikes surface F1 a glancing blow and of protecting it against adversely affecting the flame generated infra-red radiation from flame-type infra-red burners 32. Water vapor in a boundary layer on surface F1 will also interfere with the transmission of infra-red rays thereto and removal of convection heat therefrom so that striking surface F1 by stream 42 is desirable to break up this boundary layer.

If gas stream 42 strikes the radiating face of burners 32, it appears to adversely affect the flame generated infraradiation from this flame-type infra-red burner 32 by either adversely affecting the flame or "by excessively cooling the outer infra-red radiating surface on plate 7 in the aforementioned Schwank patent. The flame may be adversely affected by being blown out, sucked off the outer radiating surface of radiating plate 7 in the Schwank patent by the Venturi effect under Bernoullis Theorem, reduced in size, or at least adversely affected to reduce substantially infra-red radiation output from the radiating plate surface by preventing proper flame combustion.

Although the gas flow characteristics of nozzle 50' will depend upon the geometry of shapes, sizes and relative spacings of the components in drying apparatus 16 and of fabric element 12, it has been found in the installation in the aforegoing Table I that about 1500 cubic feet per minute of air at a discharge velocity of about 2000- feet per minute is the maximum without adversely disturbing the flame generated infra-red radiation if screen 64 is not used, which screen will be described in more detail hereinafter.

The gas moving means also includes gas exhaust opening 56 having at least (and preferably much greater) flow cross sectional area than the flow cross sectional area of gas discharge nozzle 50 and being similarly oriented with respect to surface F1 of element 12 but located on the downstream side of gas stream 42 from heating zone 40 and discharge nozzle '50. Preferably, the mouth of exhaust opening 56 is larger in dimension 50W than discharge nozzle 50 since gas stream 42 to be exhausted has swelled in volume since it has picked up heat and moisture so that a larger volume has to be exhaiusted through gas exhaust opening 56 by exhaust fan 60 through duct 58 (having duct surfaces 58a and suitable turning vanes 58b) and outlet duct 62 to the outside of drying tower 14. Duct 62 is shown schematically in FIG. 1 as two vertical outlet ducts for simplicity of illustration instead of the single outlet duct 62 in FIGS. 2 and 3. Air grills 580, one in each duct '58, may be adjustably opened to adjust the draw in its associated opening 56 by controlling the admission of makeup air.

The efliciency of heat transfer and moisture vaporization and the high quality of fabric element 12 produced are readily apparent by considering the temperature of the air being exhausted in exhaust opening 56 and the temperature of fabric element 12 at the top end of heating zone 40 in this typical apparatus 16 in tier T2 and bank B1. In the aforegoing Table I, the temperatures of fabric element 12 and of the exhausting air are without screen 64 (mentioned hereafter) respectively 200 F. and 186 F. and with screen 64 respectively 160-180 F. and 164 F. Hence, there has been a good heat transfer and scrubbing action between air stream 42 and fabric element 12 and most of the infra-red energy supplied has gone into vaporizing water since neither the discharged gas nor fabric element are above the boiling point of water. Since element 12 picks up very little more heat as it travels upwardly in tower 14 in FIG. 1, the temperature of element 12 can still be maintained at about only 180-200 F. (from Table I) at the top of apparatus 16 in tier T8, if

so desired. Also, the fabric temperature of -200 F. is well below the maximum temperature before the aforementioned fibers are damaged by heat. For example, excessive heat when element 12, if made of certain types of nylon, still contains substantial amounts of water, might cause chemical degradation at temperatures as low as 250 F. so element 12 would not be damaged by drying apparatus 16 but might be damaged by the 600 F. fabric temperature mentioned in the aforementioned Kersker US. Pat. No. 3,250,641 not using a high velocity gas stream.

If gas stream 42 is moving at too high of a velocity or if too large of a quantity of gas is flowing in stream 42, the infra-red radiation from flame-type burner 32 will be adversely affected, as aforedescribed. Reducing and eliminating this adverse effect has been found by insertion of a fine mesh gas deflecting screen 64, preferably mounted in frame 66 secured by mounting brackets 93 and 94 in FIG. 6 directly to discharge nozzle duct 48 and exhaust opening duct 58; mounted between infra-red heater panel 31 and fabric element 12 to be dried; extending generally parallel to fabric surface F1 in heating zone 40; and extending generally parallel to the direction of movement T of fabric element 12. Various mesh screen has been tried, including 8, 10 and 12 mesh screen. The mesh of the screen and wire thickness control the gas stream velocity-the finer the screen the higher velocity gas stream useable but the less infra-red transmitted. It is best to use just coarse enough screen to handle the gas velocity. Coarse mesh screen has been used to support the fine mesh screen against warping. Stainless steel, Nichrome, and regular steel wire screen have been tried. The problems occurring were warping, oxidation and brittleness under heat. It has been found most satisfactory to use an 8 mesh 0.023 inch wire diameter) ordinary hardware cloth screen of inexpensive cost and to replace the screen when it has been adversely damaged. Broadly speaking, this screen 64 is a burner shielding means intercepting the infra-red rays from the emitting surface of infra-red panel heating surface 31 to element surface F1 in heating zone 40 for preventing adversely affecting the flame generated infra-red radiation, such as by shielding the flame on infra-red heaters 32 from blowout, by gas stream 42 while permitting infra-red rays from heaters 32 or heating means 28 to strike surface F1 in heating zone 40 for drying. Broadly speaking, any suitable baffle means might be used in place of screen 64.

Gas stream 42 and screen 64 coact to provide numerous advantages. Velocity of stream 42 discharging from nozzle 50 may be as high as 5000 feet per minute with a flow of 3000 cubic feet per minute, and 6000 feet per minute velocities have been used, without adversely affecting infra-red radiation from burners 32 in aforegoing Table I. Also, a portion of the gas layer in gas stream 42 moves across the fabric side of screen 64 while heaters 32 are emitting infra-red heat so as to reduce any infra-red elevated temperature of screen 64 so as to prolong its useful life, to minimize warping and oxidation thereof, and to permit use of the aforementioned inexpensive hardware cloth. The higher velocity gas stream 42 substantially increases the speed of uniform drying while still maintaining a controlled temperature. The fabric quality produced is still better and is produced on smaller sized equipment. Hence, a great superiority is obtained by using screen 42 even though a substantial improvement, as mentioned heretofore, was obtained by using gas stream 42 without screen 64. Gas stream 42, traveling between fabric element 12 and screen 64, at high velocity accelerates the drying while screen 64 diverts this gas from the flame generated radiating surface on burners 32 to allow efficient burner operation. The higher velocity gas removes water vapor more quickly to greatly increase the drying efficiency while still maintaining fabric temperature more uniform across dimension W and at a lower temperature.

Also, this fast drying action makes possible production of cord fabric without a webbed condition, wherein the adhesive liquid forms a hardened film across the open mesh of the fabric securing adjacent cords together.

The substantial increase in drying rate and substantial reduction in drying equipment size is shown since drying tower 14 in FIG. 1 and Table I will dry coated element 18 (made of a particular fabric and weave) to the same state of satisfactory dryness while traveling in direction T in:

(1) Three tier heights when using screen 64 and 5000 f.p.m. air velocity stream 42 at nozzle 50.

(2) Five tier heights when using 3000 f.p.m. air velocity stream 42 at nozzle 50 and using no screen 64.

(3) Eight tier heights when not using either air stream 42 or screen 64.

This means that adding air stream 42 gives about a 38% reduction in height of tower 14 and adding screen 64 and faster air stream 42 gives about a 63% reduction in height of tower 14.

PLURALITY OF DRYING APPARATUSES 16 IN FIG. 2

In any given tier of drying apparatuses 16 in drying tower 14 in FIG. 1, such as tier T2, the two horizontally aligned drying apparatuses 16 straddling opposite faces F1 and P2 of fabric element 12 have certain common structures, modes of operation and advantages as they coact together, as mentioned in more detail in the following paragraphs describing the stopping of element 12 and infra-red shutdown action, reflector side plates 90, gas flow ducts 92, elimination of back-up reflector to fabric element 12, and simultaneous drying and aeration of both sides of fabric element 12, etc.

When the driving action of drive rolls 22, 23 and 24 in FIG. 1 on element 12 is shut down so as to stop the relative movement of element 12, it is important in each of the sixteen drying apparatuses 16 in tower 14 to immediately shut down infra-red radiation from heating means 28 in all apparatuses 16 and to continue the flow of gas stream 42 undiminished, by continued energization of the gas moving means, so as to relatively move gas stream 42 with respect to and over surfaces F1 and P2 of element 12 in all heating zones so as to prevent residual heat from heating means 28 from raising the temperature of and damaging element 12. This action will be described herein for only one or two drying apparatus 16 since the sixteen in tower 14 are simultaneously controlled in the same manner. Here, inlet fan 44 and exhaust fan 60 in FIGS. 2 and 3 operate continuously so as to run when fabric element 12 is stopped as well as when it is being driven in the direction T during fabric processing and drying. In fact, it is preferred to increase the gas quantity flowing in stream 42 during this infra-red shutdown because fabric element 12 is not moving and cannot escape from heating zone 40, and infra-red heating means 28 has a great deal of residual heat radiating onto element 12. Also, increased gas flow now does not adversely affect radiation from gas infra-red burners 32 since they are now shut down. Also, it is desirable either to cover the radiating face of each panel 31 or to retract each panel away from fabric element 12 and screen 64. The mechanism to be described hereafter provides this action for both drying apparatuses 16 in tier T2 in FIG. 1 (both in banks B1 and B2), and is shown in more detail in FIGS. 2 and 7. In FIG. 7, rotation actuated switch 68 (having its switch contact open during stopping of drive roll 23 and having its switch contact closed when fabric element 12 is being driven in direction T by the drive rolls) opens its switch contact upon stopping of movement of fabric element 12 in direction T in heating zone 40 so as to de-energize each solenoid gas valve 35 controlling main burner gas line 37 to each panel 31 in tier T2 in FIG. 2 and de-energizes solenoid operated four-way valve 72 by breaking their energizing parallel circuits between power lines L1 and L2. Deenergizing solenoid operated 4-way valves 72 connects air pressure line 73 to one end of double acting burner panel retracting cylinder 74 and to one end of double acting gas flow damper cylinder 76 and connects its exhaust port 72a to the other ends of these cylinders. This action extends the length of cylinder 74 so that its upwardly moving piston rod in FIG. 2 swings arm 78 clockwise on pivot 79 so that bell cranks 80 on parallel pivot shafts 79, connected by link 82 will cause bell cranks 80 to swing clockwise in FIG. 2 to retract panels 31 away from element 12 from their solid line to their dot dash line positions since the opposite ends of links 82 and 84 and the distal end of arm 78 have pivot connections. The upper end of each panel 31 is supported by at least one pair of trolley rollers 86 travelling in opposite channels of I-beam 87 forming one of the upper structural members 14a in each apparatus 16 in drying tower 14. This action also causes double acting gas flow damper cylinders 76 to move quadrant-type damper 88 in FIG. 2 from a partially open position in gas nozzle duct 48 assumed while fabric element 12 is driven in direction T by the drive rolls during normal drying to a fully open position during infra-red shutdown to increase the gas discharge rate from nozzle 50 to increase gas stream 42 for cooling both screen 64 and surfaces F1 and F2 of element 12 to protect them against residual heat from straddling heating means 28. When element 12 begins to travel in direction T, switch 68 closes to reverse this action so as to open gas valve 35, to contract cylinder 72 to advance panels 31 back to their solid line positions, and to move damper 88 back to its partially open position so that each apparatus 16 is now ready for drying again. During this reverse action, four-way valve 72 moves to its opposite position to connect air pressure line 73 and its exhaust port 72a respectively to said other and said one ends of said cylinders in the conventional four-way valve operating manner to reverse the action of cylinders 74 and 76.

Each of the two panels 31 in any given tier, such as tier T2 in FIGS. 1-3, has secured to each of its vertical side surfaces in FIGS. 6 and 8 reflector plate 90, four in number for each tier, adapted to telescope together over each edge of fabric element 12 in straddling relation ship when the burner panels are in their solid line positions in FIG. 2, as shown in FIG. 8. Then, these four reflector plates 90 form two generally parallel reflector means extending along direction T of relative movement of element 12 and straddling the opposite edges of element 12 for heating these edges in heating zones 40 more uniformly by infra-red radiation by reflecting the infrared radiation back onto these edges of the fabric, since these edges would not otherwise get sufficient radiation since they are close to the edge of panels 31. Hence, these reflector plates assure uniformity of infra-red radiation over full width W of fabric 12 by capturing the infra-red radiation that would otherwise escape laterally through the gap between panels 31.

Flow ducts or flow channels 92 are formed, one duct on each side of fabric element 12, for conveying the gas in each gas stream 42 as an air curtain from its discharge nozzle 50 to its exhaust opening 56. Each gas flow duct 92 extends along the length of element 12, has element 12 surface F1 and F2 as one wall thereof, and is mounted to receive gas stream 42 from discharge nozzle 50 for keeping gas stream 42 flowing over and close to this element surface and for discharging the gas stream 42 into discharge opening 56 for exhausting from drying tower 14.

Each vertically extending flow channel or duct 92 for gas stream 42 is formed by surface face F1 or P2 of element 12, reflector plates 90 and the element 12 side face of screen 64 with these two ducts 92 each being rectangular in cross section, generally parallel, and straddling element surfaces F1 and F2. Although each screen 64 may be secured to its associated burner panel 31, each screen 64 is preferably secured in FIG. 6 at its upper and lower ends respecitvely by mounting brackets 93 and 94 (one at each corner) to ducts 58 and 48 so that screens 64 will be fixed against lateral movement relative to gas discharge nozzles 50 and element surfaces F1 and F2 in heating zone 40, and therefore will not move with panels 31 as they are retracted to the dot dash line positions in FIGS. 2 and 6 during infra-red shutdown. Hence, there is constant geometry between screens 64 and element 12 for controlling the thickness of gas streams 42 straddling element 12, which geometry will not change even though-panels 31 are movable between these solid and dot' dash line positions. Movement of reflector plates 90 with retractable burner panels 31 between the solid and dot dash line positions in FIGS. 2 and 6 does not matter because they will return to their telescoped relationship to form the sides of flow ducts 92 each time burner panels 31 are moved to their advanced and solid line position in FIG. 2.

Each duct 92 plays an important part during travel of its stream 42 from discharge nozzle 50 to exhaust vent 56. Duct 92 guides, holds laterally compact and prevents lateral dispersion stream 42 to maintain the flow action of stream 42 in direction T along element 12 and toward exhaust vent 56 while keeping stream in close contact with element face F1 or F2.

Although two ducts 92 and four reflector plates 90 have now been described for two apparatuses 16 in FIGS. 2, 3 and 8 for convenience, it should be apparent that a single duct 92 straddled by only two reflector plates 90 give the same advantages for a single apparatus 16. There are other advantages in having two drying apparatuses 16 facing each other at each tier, such as tier T2 in FIG. 1, with one apparatus 16 in each bank B1 and B2. Then, these two heating apparatuses 16 are mounted with their two heating zones 40 having sandwiched therebetween the generally coinciding opposite faces F1 and P2 of element 12 so that each dries one of the opposite generally coinciding parallel faces of element 12. This structural arrangement and coaction has a higher drying heat; simultaneously dries both sides of fabric element 12; more rapidly dries fabric element 12; and requires no reflector behind element 12, such as would be necessary if only one drying apparatus were used. Such reflector frequently has a short useful wear life since it gets tarnished and tends to melt under the hot infra-red radiation heat.

The eight drying apparatuses 16 in bank B1 in FIG. 1 in tires T1-T8 arranged in series along direction T of travel of element 12 have certain advantages. Each of these apparatuses 16 has its own gas discharge nozzle 50 and gas exhaust opening 56 for generally uniformly processing width W of element 12 in series arranged heating zones 40 as element 12 moves upwardly in FIG. 1 past these eight series arranged drying apparatuses 16 in bank B1. Each of these eight drying apparatuses has its own vertically traveling gas stream 42 formed from relatively fresh, dry, cool air at ambient conditions sucked in from outside drying tower 14 for its discharge nozzle 50 and has water molecule saturated, or at least heavily laden, air (substantially raised in temperature) exhausted through exhaust opening 56 and outlet duct 62 at the top of drying tower 14 so as to not interfere with the flow of fresh, dry air into tower 14 for discharge nozzles 50. Having eight separate gas streams 42 is a substantial advantage over having a single gas stream 42 passing from the bottom to the top of drying tower 14. This single gas stream would (after it traveled more than one tier in height) be too heavily laden with water molecules to provide an effective scrubbing action, be too heated up to provide an eflective temperature control by cooling element 12, be too heavily concentrated with water molecules so as to prevent effective infra-red transmission from heaters 32 to element 12, have lost its upward velocity so it would no longer scrub off the water molecules or remove the convection heat, not 'be able to be kept confined to surface F1 or P2 of fabric element 12 because it would lose its upward velocity, and not be able to be confined to a compact stream but would spread laterally and thus be totaHy useless. The advantage of dividing a single gas stream into eight separate series arranged gas streams 42 becomes more apparent when one realizes that the free vertical travel of each gas stream 42 at each tier in FIG. 1 is about eight feet vertically in the typical installation in Table I while a single stream would have to travel about feet traveling the vertical heights of drying tower 14. Also, it is possible by using the sixteen separate drying apparatus 16 in drying tower 14, arranged in horizontally opposed pairs and in eight series arranged pairs, separately to control the infra-red heating action and flow of gas stream 42 in each component apparatus 16 to match the existing and desired conditions of temperature and moisture removal from element 12 as it is progressively dried as it moves vertically through drying tower 14. This would not be possible if a single gas stream were used for the whole height of tower 14. Also, it has been found during operation of drying tower 14 that the temperature of element 12 and the temperature of the discharged air at the top of each tier T1-T8 can be controlled to be approximately the same even though element 12 moves upwardly in tower 14 and becomes progressively drier.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive with the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by U.S. Letters Patent is:

1. An apparatus for drying yarn or fabric fibers in a continuous length element, comprising:

a heater with a flame for generating infra-red radiation,

disposed in a heating zone;

means for moving the continuous element past the heater; means for moving a stream of gas adjacent the heater in parallel and contacting relation with the continuous element;

means separate from the heater and interposed between the heater and element during normal operation of the heater to dry the fibers, for shielding the flame of the heater against the gas stream without disrupting the infra-red radiation against the element.

2. The apparatus as set forth in claim 1, wherein the flame shielding means includes a wire screen.

3. The apparatus as set forth in claim 2, which includes means for holding the wire screen in parallel relation to the moving element to form an air passageway for the gas stream.

4. The apparatus as set forth in claim 3, wherein the screen size is between 8-12 mesh.

5. An apparatus, as set forth in claim 1, with generally parallel reflector means extending along the direction of relative movement and straddling the edges of said element for heating the edges of said element in said heating zone more uniformly by the infra-red radiation and for providing a flow channel for said gas layer in said heating zone straddled on opposite sides by said element and by said shielding means.

6. A combination, comprising two of the apparatuses, as set forth in claim 5, mounted with heating zones having sandwiched therebetween generally coinciding opposite element faces so that each dries one of the opposite generally coinciding faces of the element with said gas flow channels being generally parallel and straddling said element.

7. A combination, as set forth in claim 6, with each of said apparatuses including said burner shielding means being a screen extending generally parallel to the direction of element relative movement, extending generally parallel to the associated face of said element in said heating zone, and being fixed against lateral movement relative to said last mentioned face in said heating zone,

said gas moving means having a portion of its gas layer moving across said screen during energization of said heating means for reducing any infra-red elevated temperature of said screen, and

heating cutoff means for moving said infra-red heating means relative to said screen and element during infra-red heating shutdown and stopping of relative movement of said element with the relative positions of said screen, element in said heating zone, and gas discharge means being maintained,

said gas moving means being energized for relatively moving the gas layer with respect to said last mentioned face of said element in said heating zone during infra-red shutdown of said heating means and shutdown of said drive means for preventing residual heat from said heating means from damaging said screen and said element not now relatively moving.

References Cited UNITED STATES PATENTS 3,406,954 10/1968 Fannon 2633 JOHN J. CAMBY, Primary Examiner U.S. c1. X.R.

' g;;g UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 5 ,375 Dated 7 7 Inventor) D. C. Sanders, Jr.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

instead of 209 180 gm 2 L iii- LLB mom mm mm I. W, m. Attesfin Officer Dominion at Patents

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