US 2225166 A
Description (OCR text may contain errors)
Dec. 17, 1940. P. ERBY 2,225,166
y WEB DRYING APPARATUS Filed oct. e, 195s 2 sheetsfsheet 1 INVENTOR. ,QI/A /P EEEY ATTORNEY Dec. 17, 1940. P. ERBY wEB DRYING APPARATUS Filed Oct. 6, 1938 2 Sheets-Sheet 2 R O m E V m P/-l/L/p EZBY ATTQINEYS Patented Dec. 17, A194.0
APATENT OFFICE WEB DRYING APPARATUS Philip Erby, Chicago, Ill., assignor of one-half to Christopher Statter, Crystal Lake, Ill.
Application october s, 193s, serial N6. 233,565
9 claims. (ci. :i4-4s) 'I'his invention relates to improvementsQ in web drying apparatus. f
It is the primary object of the invention to provide a simplified means for ensuring the speedy drying of a web of paper or the like. is a further purpose of the invention to provide means whereby a drum, over which the web to be dried is passed, can be thoroughly and adequately heated from the interior by gases which have not yet been used to pick up moisture from the web, whereby the heat imparted to the drum is the high temperature heat of such gases before the gas temperature is resoi duced by evaporation, the same gases being later recirculated about the exterior of the drum in direct contact with the web to pick up the moisture driven from the web by the heat.
It is my furtherA purpose to provide a complete burner and safety control mechanism rotatable with the drum about which the web to be dehydrated is passing.
Otherl objects will be apparent from ing disclosure.
I have shown not only a single drum but a multiple drum arrangement embodying my invention and arranged in each instance to utilize hot gases, preferably products of combustion, without burning the web to be dried.
In the drawings:
Fig. 1 is a view in longitudinal section of apparatus comprising a single drum and embodying my invention.
Figs. 2 and 3 are respectively detail views in cross section taken on the section lines 2-2 and 3-3 of Fig. 1.
Fig. 4 is a diagrammatic view showing partially in end elevation and partially in section,
the followthe arrangements for moving the gaseous ma-V terial and the web to he dried through such apparatus as illustrated in Fig. 1.
Fig. 5 is a diagrammatic view taken in transversesection through the casing and showing an end elevation, a set of drying rolls, and gase-v dried is fastened over the roll or drum 1, one
end of which is carried by spider 8 from a shaft 9 driven from motor I0 through the speed reducer II and chain I2. f
'I'he other end of the 'drum has a tubular eX- tension I5 of reduced diameter which is carried on supporting rollers such as those shown at I6. The air inlet ports at I1 within the tubular drum extensions I5 are covered by the screen I8 to prevent iire propagation beyond the connes of the drum. The larger end of the drum, adjacent the spider 8, is provided with a stationary closure at I9. having an opening 20 through which the products of combustion are removed from the drum. Spider 8 carries a screen 2| rotatable with the drum and the spider across the opening at 20 to prevent flame propagation beyond this end of the drum.
The gas burner comprises a series of concentric nozzles through which gas and air in proper proportions are admitted to the drum. 'I'he larg- Iest nozzle 2I0 is a vfrusto-conical tting carried bythe admission end of drum 1 surrounding the admission port 22 which is provided in such tting. The larger end' of the fitting is open at 23 to admit the secondary air. -Into the opening projects the pilot burner 24 and thermostat 25 which, being of generally conventional construction, are not described in detail. The pilot light 24 is supplied with gas through the branch pipe 26, the gas being ignited by a spark plug 21 supplied with current throughvslip ring 28 and brush 29 from the spark coil diagrammatically illustrated at 30. Another slip ring 3| and brush 32 supply current to a conventional solenoid valve 33, the brush being so connected to /the main motor circuit as to cut off the 'gas flow when the motor is not ln operation, and to open the burner for gas flow when the motor is in operation. .I
A secondary gas valve at 34 is likewise of conventional form and arranged to be latched open by a detent` (not shown) which is controlled by the thermostat 25 through the line 35. The valve may be cocked open manually by the chain 36 when the pilot light is in operation to keep the thermostat hot, but if the pilot light at burner 24 is extinguished the thermostat 25 cools and trips the detent to allow the valve at 34 to close, thus cutting off the gas from the valve nozzle 31. 'I'he gas nozzle 31 directs the gas through a Venturi tube at 38. Primary air enters around the gas nozzle and iiows through the Venturi tube entraining secondary air at the nozzle 2IIl to maintain combustion at the point where the mixed gas and air are ignited by the pilot burner 24 and projected into the drum 1.
'I'he gas supplied t0 nozzle 3'I enters through pipe 40 which provides mechanical support for the slip rings 28 and 3i, being flxedly mounted in the tubular drum extension I5 at the inlet end thereof. The gas pipe 40 is provided with a flanged head 4I swiveled to the gas main 42, such main being provided with a casing 43 in which packing 44 is confined under pressure of spring 45 to permit the pipe 40 to rotate with ,the drum in respect of the relatively stationary supply main 42.
It is not important which pipe carries the fchambered head or casing 43, nor what specic means is used to restrict the pipes against undue separation, but it is desirable that some freedom of axial motion be provided for in addition to relative rotation. The flange 4I has for this purpose substantial clearance from the packing gland element which closes its recess in casing 43.
Directly in the path of the ame projected into the drum from the gas burner is a refractory baille '5D carried by a transversely extending support 5I to which the adjusting screws 52 are swiveled. Ihese screws are threaded into the end of the drum to adjust the baille to and from the burner so that the exact point may readily be found at which the flame will be caused to travel through the drum in a manner to heat its surfaces uniformly. The approximate path of the ame is indicated by lines drawn from the burner to the baiile and through the drum in Fig. 1. The ame traverses the inner periphery of the drum closely adhering to the inner peripheral surfaces to give up the heat of the incandescent gases directly to the metal of the drum, thereby highly heating the web which is traversing the drum.
'I'he type of burner illustrated is one which requires a rapid circulation of air through the burner to maintain the flame. Although means hereinafter to be described is provided for maintaining a partial vacuum within the casing 54, it is preferred that an additional air circulating means be provided to draw gases directly fromv the drum. The reason for using the additional air circulator is to avoid the extinguishing of the flame which might follow if a workman should open a door in casing 54 for the purpose of gaining access to the web while the burner was in operation. Otherwise the intervening blower might be omitted.
From the drum opening 20 in the stationary drum unit I9 leads pipe 55 which may be provided with a screened auxiliary inlet at 56. Pipe 55 goes to the inlet or eye portion 51 of the intermediate blower 58 above referred to (Fig. 4) and this intermediate blower discharges into the casing 54 through pipe 59 over theset of bailles 60 which distribute the flow of gas over the web 62 which is passing through the casing between the parent roll 63 and the rewind roll 64.
The gases resulting from combustion of the burner have lost some of their heat through direct contact with the interior of the drum. Additional heat has been given to the extra air admitted at 56 and 65, but such gases have not yet come into contact with any moisture and consequently areextremely dry at the time they flow over therweb on the surface of the drum. Evaporation is therefore rapid and it may be facilitated by the fact that the exhaust blower .66 which withdraws the gases and vapors from the casing through pipe 61 preferably maintains the interior of Vthe casing under partial vacuum.
In other words, the capacity of blower 66 preferably exceeds the capacity of the intermediate blower 58 to enhance the rapidity of the vaporization of the moisture from the web.
In the arrangement shown in Fig. 5 the web passing from the parent roll 63 to the rewind roll 64 passes over two series of rolls. Each of the first four rolls encountered by the web at 68, 69, I6 and 'II is identical with roll 1, each being heated by its own separate burner. The gases emerging from the stationary heads I9 of these first four rolls are collected in the pipe 12 through its several branches, and led to the intake eye of the intermediate blower 13. By this blower the collected gases are again distributed through pipe 'I4 and its branches to the input ends of the rolls 15, 16, 'I'I and 18, these being the next rolls encountered by the web as it traverses casing 79. 'Ihus far the hot gases have not yet come in contact with the web to carry off the moisture therefrom. From the stationary heads web, and the gases are then withdrawn from casing 'I9 through the suction blower 90 which, as above explained, preferably keeps the entire interior of the casing I9 normally under partial vacuum.
It will be understood that -whilev the web may be of any material, and While the liquid:to be vaporized therefrom may constitute a liquid other than water, I have noted the problem of paper drying as a means of illustrating the invention. For the evaporation of water from a paper web the organization herein disclosed has been found to have particular utility. Notwithstanding the intense heat applied to the interior of the drum, the motion of the paper over the drum may be so rapid and the rate of extraction of water therefrom be so high as to keep the paper suiciently cool to prevent it from scorching. The problem of uniformity in drying has been solved by the'mechanism herein disclosed, and by employing two separate blowers disposed in the system in the manner indicated I am able to maintain the burner in operation and to maintain flow through the system in thedesired manner.
The drum extension may be of any desired dimensions, and is shown as an example of one convenient means for providing a restricted air passage about and through the burner tothe interior of the drum while supporting the burner largely externally of that portion of the drum on which the web is carried, so that the flame can be uniformly distributed on the web carrying surfaces.
By means of the invention the distribution of heat and the controls herein provided protect the web against damage notwithstanding the extremely high temperatures and direct heat which are used. As an example of such temperatures it may be stated that Ifor lb. wall paper Vthe drum 'temperature is preferably about 850 F. and fthe surface or peripheral speed is approximately 350 feet per minute. This enables ythe web tc be dried with much greater efficiency than has heretofore been possible in the use of steam. It is y the surface of the web are virtually free of oxygen, thus enabling much higher temperatures to be used than would be possible if air or other oxygen-containing gases were used. Moreover, because of this fact, it is possible to dry on this ...and other similar apparatus webs containing highly inammable and explosive gases and also materials which, in the presence of oxygen, would suffer changes of color.
For example, highly colored wall papers are dried with utmost rapidity at temperatures which, in the presence of oxygen, would result in changes in the color of the dyes and pigments used. Also, webs of cloth containing naphtha can be safely passed over a drying roll and subjected to high temperature gases in accordance with this invention and thus dried almost immediately without having the naphtha reach the air of the plant in which the drying operation is conducted. The gases reaching .the fabric are so completely free of oxygen due to the fact that they are products of combustion, as to elimina-te any .possibility of explosion. Heretofore products containing naphtha have been dried by festoom'ng them over long series of rollers and the problem of ridding the plant of the naphtha vapors has involved a frequent exchange of all of the air in the establishment with consequent enormous heating bills during cold seasons.
1. Web drying apparatus of the character de- -for drawing heated gases from the .drum and maintaining a partial vacuum therein and propeiling such gases into contact with said material, and a foraminous elementin the path of such gases comprising means for preventing flame propagation from lthe interior of the drum to the gases contacting said material.
2. In a web drying apparatus of the described class, the combination with a drum having a web supporting periphery, means for maintaining combustion within the drum, gaseous conduit means leading from the drum interior to a point adjacent the web supporting periphery-thereof, and propelling means associated with saidcondui-t means for drawing heated gases from the drum interior and dispelling said gases adjacent the web supporting periphery.
3. In a machine for drying webs of paper and the like including a housing, a series of drums in said housing 'and means for feeding the web successively over peripheral surfaces of said drums, at least one of said drums being provided with a burner at one end and an outlet at the other end, baiiie means within the drum provided witli'the burner for distributing flame and products of combustion from said burner along its interior surfaces, means for propel-ling the heated gases from lthe drum outlet int'o the housing, and means for preventing flame from being so circulated,
whereby the peripheral wall of the drum may be kept at a high temperature and the gases discharged therefrom utilized to provide a moisture absorbing atmosphere in contact with the web. 4. vWeb drying appara/tus of the character described including a rotatably mounted cylindrical drum provided at each end with an aperture, a tubular housing surrounding the aperture at one end and having disposed .therein a burner of the Bunsen type positioned to project flame" through the aperture longitudinally of the drum, baille means disposed within said drum in the path of the projected ame and adapted to distribute the flame and heated gases along the interior surface of the drum wall, said baiiie being adjustable in an axial direction, a housing enclosing said drum and provided with inlet and outlet apertures, a conduit leading from 'the aperture in the drum end wall opposite the burner to said housing inlet and having disposed therein means for drawing heated gases from the interior of the drum and circulating them through the housing, and means for passing moisture containing webs through said housing and arcuately over a portion of said drum whereby the dry heat from the iiame within the drum and the hot gases within the housing co-act to vaporize the moisture carried by saidy web.
5. In a web drying apparatus, the combination with a web supporting drum. and means supporting the drum for rotation, said drum having a tubular extension at one end, of a burner mounted in said extension and adapted to deliver flame and products of combustion into said drum, burner control mechanism including a pilot burner mounted4 in said extension, electrical means for igniting said pilot burner, electrical feeding connections for said control mechanism including slip rings rotatable with said tubular extension and having brushes acting thereon, and means for supplying fuel to said burner during drum rotation.-
,6. In a web drying apparatus of the character described, the combination with a drum mounted for rotation and having a peripheral web supporting portion, and/a centrally apertured end wall, a frusto-conical housing positioned exteriorly of said drum adjacent said end wall aperture and axially provided in its larger end with a spider, a flaring tube aligned with the end Wall aperture and having its larger end supported by the spider and provided adjacent its smaller end with air admission ports, a jet tube aligned with the smaller end of the rst mentioned tube to direct fuel thereto for the carburetion of primary air admitted through said ports and the. carburetion of secondary air admitted to said spider, a supply pipe in operative connection with said jet tube, and means for withdrawing gases from said drum whereby to aspirate primary and secondary air currents into said drum for the proper combustion of fuel supply.
7. A Ydevice of the character described, comprising the combination with a rotatable drum provided at one end with a supporting shaft and spider, and a drum head provided with an outlet, power means for exhausting gases from said drum through said outlet, the end of said drum remote directing flame into said drum through said inlet,
and a baille disposed within the burner end of the drum in the path of ame projected by said burner, whereby to distribute the burner heat over the drum walls.
8. In an apparatus for drying continuous webs I of paper and the like, the combination with a drum and means for guiding the continuous web thereover at substantial rates of speed, of a combustion burner within the drum for heating the drum, a casing in which said drum operates, means for discharging the products of combustion from the drum into the casing whereby to produce a substantially oxygen-free atmosphere therein, and means for exhausting gases from the casing at a rate exceeding the rate at which they are delivered thereto, whereby a web traversing said drum derives heat from the drum and from the atmosphere of said casing while subjected to partial vacuum adapted to enhance the rate of moisture evaporation from said web, whereby to cool said web below the temperatures to which it would be subject at atmospheric pressure and to evaporate moisture from the web at a lower temperature than that which would berequired to produce like evaporation at atmospheric f pressure, and whereby the high speed of web travel, the relatively oxygen-free atmosphere in which the web is dried, the relatively high rate of evaporation from the web, and the cooling eiect produced by such evaporation all combine to enable the web to be dried rapidly and without discoloring oxidation or ignition.
9. In an apparatus for drying Webs of paper and the like, the combination with a suitable housing', of a web supporting drum therein, means for maintaining combustion at one end of the drum and passing the products of combustion therethrough and delivering the same into the housing exterior to the drum and in contact with the web, and suction means for maintaining a partial vacuum in the portion of the housing through which the web passes to prevent excessive heat tending to discolor the web or cause the same to ignite.