US2144919A - Apparatus for and method of drying web material - Google Patents

Description

Jan." 24, 1939- A. G. GAUTREAU 1 APPARATUS FOR AND MFITI-IOD'TOFQDRYING WEB MATERIAL Filed Jufie 24, 1957 3 Sheets-sheeti Niven-Tor. Arthur G. GauTte Q byMMK W r L I ys.

Jan. 24, 1939. A. a. GAUTREAU 2,144,919

v APPARATUS FbR AND METHOD OF DRYING WEB MATERIAL Filed June 24, 1937 3 Sheets-Sheet 2 l'nvenTor. ArThur G.GquTreau Jan. 24, 1939. A. G. GAUTREAUV' 2,144,919

APPARATUS FOR AND METHOD OF DRYING- WEB MATERIAL W l v Filed June 24, 1937 3 Sheets-Sheet 3 FigAQ I v lnvenTor.

Arthui GCSuuTrecau WM MIW ATTys;

Patented Jan. 24, 193? PATENT OFFICE v wan MATERIAL I Arthur G. Gautreau, Quincy, Mass., assignor to' Andrews and Goodrich,

Inc., Dot-cheater, Masa,

- a corporation of Massachusetts Application June 24, 1937, Serial No. 150,085

I 7 Claims. (01.34 48) This invention relates to drying web material and particularly to that system of drying web material according to which the'material is floated on a stream or current of drying medium, the latter serving not only to dry the web material but to support it during the drying operations One of the advantages inherent in this system of drying is that since the web material is supportedon the drying medium duringthe drying operation it will be held out of contact with any rigid supporting surfaces and thus the drying will be done without producing any marks on the web material such as might be produced it theweb material were supported on hard sur-- web-o1 material will be practically tension-free l faces while it was being dried.

In drying web material .by the above-men'- tioned method the drying medium is usually delivered against the under side 01' the web material through nozzles in the form of slots extending transversely to the length of said material, and if the space in which the web material is floating on the stream of drying medium is open'at the sides, then although there is a current of drying medium-moving lengthwise oi the web and on which it is supported, yet a part of the dryingmedium which is delivered through the slots s flowing out laterally through said open sides, and such outwardly flowing portions of drying medium apply a force to the web tending to move it transversely. I

So long as the web is correctly centered the I force tending to shift. it transversely in one direction which is applied thereto by the portions 01 the drying medium flowing outwardly on one Side of the drying space is balanced by the force applied to the web tending to shift it transversely in the other direction by the portions of the dry? ing medium which flow outwardly through the other open side oi the drying space. If, however, the web moves slightly of! center then these two opposing forces become unbalanced, and the force tending to move the web laterally in one direction will be greater than that tending to move it in the opposite direction with the result that the web will be carried further oil center.

It is one of the objects of my present invention to provide an improved drying apparatus ior, and an improved method of, drying web material by which the web is fioatingly conveyed through the drying space by a stream of gaseous drying medium which flows through said spaceirom one end to the other, and by which currents are establishedin said stream of'dryin'g medium that apply to the web acorrective force in a lateral 'directionfl'whenever the web tends to move side- 'ways in said space as it is being iloa tingly. conveyed by the stream. With this invention, therefore, the web of material will be automatically maintained inlts central or normal position during its traveling movement through the drying is space and any tendency of the web to s'lue side.- ways will be immediately corrected by the corrective force of the currents which are thus established in the flowing stream of drying medium.

Another object of my present invention is to 10 provide an improved method of and apparatus for drying web material using the principle of floating, the web material on a current of drying medium; according to which improvements the both longitudinally and transversely while it is being dried and will also be delivered from the 'drying chamber in this tension-free condition.

In order to give an understanding of my'in vention I haveillustrated one embodiment of the 20 invention in the accompanying drawings which "will now be described after which the novel features will be pointed out in the appended claims.

In the drawings:

invention; n A

Fig. 2 is a section on the line 2-2, Fig. 1;

Fig. 3 is a top plan view of one set of nozzles and suctionports; g Figs. 4 and 5 are views similar to Figs. 2 and 3 but showing the manner in which the web is restored to normal position when it tends toslue sideways.

In the drawings l indicates the web of rial which is \to be dried and this web material may be either cloth, paper or any other similar material. As stated above the method involves that known principle of drying the web by floatmate-' 3 ing it in or through the drying space or chamber 40 2 on the drying medium. For this purpose the bottom wall 3 of the drying space or chamber 2 is formed with a plurality of nozzles. 4 through which drying medium is delivered. against the under side of the web I at sufllcient velocity and 45 sults are secured where the nozzles are arranged to deliver the jets of drying medium'again'st the web material at an angle from twenty to thirty degrees.

These nozzles 4 are shown as in the form of slots extending across the bottom wall 3 ofthe space and with nozzles of this construction the jet of drying medium issuing from each nozzle will have a sheet-like formation. These nozzles or slots 4 communicate with a trunk or duct 5 which is connected to the discharge end of a fan or blower S, the latter delivering the drying medium under the desired pressure. For performing a rapid drying operation it is advantageous to have the jets delivered at a high velocity since the speed of drying of a web has a direct relation to the velocity of the drying medium flowing over or against the web.

If, however, the drying medium is issued from .the nozzles at high velocity it is desirable to provide means acting on the top of the web to hold it in place and to prevent it from being blown or forced too far away from the wall 3 by the jets of drying medium issuing from the nozzle 4. One means for accomplishing this end is to provide means for directing jets of drying medium against the upper .face of theweb at sumcient velocity and in such volume as to hold the web in its desired relation to the lower wall 3 of the drying space 2. In the construction herein illustrated there is provided an upper wall or roof I for the drying space 2 which is formed with nozzles 0 similar to the nozzles l and through which ing medium flowing over the wall 3 and on which the web is floated and by which it is conveyed through the drying space 2.

The blower It produces through the nozzles 8 jets l2 of drying medium which impact against the-upper face of the web to merge to form a stream 36 of drying medium flowing along the roof or upper wall I of the drying space, and

which serves to prevent the web material from contacting with said upper wall.

The blowers 6 and ill will be so operated that the velocity and pressure of the jets Ii impinging against the lower face of the web will have such a relation to the velocity and the pressure of the jets l2 impinging against the upper face of the web that said web-will be held centrally in the drying space 2 and will be floated along on and by the stream of drying medium, said stream constituting the means by which the web is At the delivery end of the drying chamber there is provided a curved delivery surface l3 which forms a continuation of the wall 3 and over which the stream 35 of. drying medium flows as indicated by the arrows in Fig. 1. The'stream of drying me:- dium flowing over this curved surface i3 supports the web and holds it out of contact with said surface so thatas the web is delivered from thedrying chamber it will, as it were, ride onthe stream of drying medium over but out of contact with the surface l3.

Means are provided for feeding the web i to the drying chamber and':regulating the feed thereof, and while any appropriate means for this purpose may be employed 1 have herein shown a feed apron H which is positivelydriven and which is carried by two rollers l5 and IS. The web I, which may be taken from any suitable source, passes onto the upper arm ll of this feed apron and is carried thereby and is delivered from the feed apron into the drying space 2. The friction of the web on the feed apron is sufilcient to feed the web forward, and the portion I of the web which is within the drying chamber 2 is fed forward by the streams of drying medium flowing along either side of the web and produced from the Jets H and I2. As stated above, as the web leaves the drying chamber it is carried by the stream of air flowing over the delivery apron l3. The cloth is thus fed throughtype is the tendency of the web to slue sideways during its passage through the drying chamber especially if the drying chamber is open at the sides. My present invention provides a novel construction and novel method by which any tendency of the web to slue sideways will be counteracted by currents set up in the stream of drying v medium by which the web is floatingly conveyed through the drying chamber. For this purpose the lower and upper walls 3 and I of the drying.

space 2 are provided with suction ports ll which are situated centrally of the web, said ports being connected to a suction apparatus so that part of the currents of drying medium delivered through the nozzles '4 and I will be returned through the suction ports.- Each suction port leads into a chamber l8 extending transversely of the web and the chambers ll for the ports I! in the floor 3 of the drying space 2 are connected at their ends to two ducts 20 which lead to a suitable suction. apparatus, while the suction chambers ill with which the ports in the upper wall I of the drying space 2- communicate are connected to other ducts 2| which also lead to a suitable suction apparatus. Any suitable suction apparatus may be employed for this purpose, but as there is some advantage in re-circulating the current of drying medium I have shown the ducts 20 as connected to the inlet ports 22 of the blower 6 and the ducts 2| as connected to the inlet ports 23 of the blower l0.

' The provision of the suction" ports I8 interspersed with the nozzles 4 and 8 through which the high velocity jets are delivered produces a movement of the drying medium-indicated by the arrows in Figs. 2 and 3. A portion of the drying medium flows longitudinally of the drying space 2 as indicated by the arrows a, b, and since the drying space 2 is open and unobstructed at the edges as shown at 24 there will be a constant drift of a portion of the drying medium out-- wardly through these open sides 24 as indicated by the arrows c, d. The suction produced at the ports i8 will draw portions of the drying medium downwardly through said ports into the suction chambers l9 and this will establish currents in the drying medium indicated by the arrows e, f. The portion of the drying medium represented by the arrows a, b and which flows longitudinally of the drying space forms a stream on which the web is floatingly conveyed through the apparatus. Under normal conditions when the web dryingmedium due to the suction at the suction ports l8, and whichare indicated by the arrows e, 1 apply forces to the web which normally balance each other, the currents indicated by the arrows I tending to move the web toward the left in Fig. 2 and the currents represented by the arrows e tending to move the web to the right.

So long as the web remains. centrally in the space these currents indicated bythe arrows c, d, e, f are balanced. If, however, the web tends to move sidewise into the position shown in Fig. 4, for instance, 'then the extra weight of the edge 39 of the web will not be properly supported and will tend to sag, thus choking the space through which the drying medium drifts outwardly as indicated by the arrows d. The drying medium will always tend to flowin the direction of least resistance and any-sagging of the edge 38 of the web will increase the current of drying medium represented by the arrows I which flow into'the suction :ports l8, and also result in a freer outward drifting flow of the drying medium at the left-hand open edge 24 as indicated by the arrows c. The currents of the drying medium indicated by the arrows f and c are, therefore, increased and the increasing of these currents tends to float the web back toward its central position.

If the web should be carried beyond its central position toward the left or should slue sideways toward the left for anycause, then the volume of thecurrents represented by the arrows e and at will be increased in the manner above described which will .result in applying a corrective force to'the web tending to float it back into central position again.

In accordance with this method, therefore, there are established in the stream of drying medium by which the web is floatingly conveyed through the drying space currents which tend to hold the web from sidewise movement and which apply to the web a corrective force in a lateral direction whenever the web tends to move sideways in the drying space.

Where the re-circulation feature is employed it is desirable that the current which is re-circulated should be heated after it has been withdrawn from the drying chamber and before it is returned thereto, and for this purpose I propose to employ heaters 25 in the return ducts 20, II.

I Each heater is provided with an intake 26 open to the atmosphere which is controlled by a suit-, able valve 21. By manipulating these valves-21 the degree of suction produced by the fan may be regulated to secure the desired result.

I claim:

1. An apparatus for drying web material having a wall forming the bottom ofa drying space which is open at its sides and through which the web may pass in the direction of its length, said wall having a plurality of nozzles for delivering the drying medium against the under face of the web, each nomle extending fromone side to the opposite side of said'space and being so shaped and disposed as to deliver-its Jet of drying mmlicm against the web at an acute angle and in tion in which the web is moving, said wall also having suction ports interspersed with the nozales and situated in a row along the center line of said drying space, suction ports being relatively short as compared with the nozzles in a direction transversely of the direction of movement of the web means to produce suction at' said suction ports, and means to deliver jets of drying medium through said nozzles thereby forming a stream of drying medium flowing through said space on which the web is floated and conveyed through said space in the direction ,of its length, portions, of said stream being drawn downwardly through the suction ports and portions flowing outwardly through said open sides whereby there web, each nozzle extending from one side to the oposite side of said space and being so shaped and disposed asto deliver its jet-of drying medium against the webat an acute angle and in adirection in which the webis moving, said wall also having suction ports interspersed with the nozzles and situated in a row along the center line of said drying space, the dimension of the suction .ports in a direction transversely of the web being only a fraction of .the transverse dimensionof said space, a curveddellvery section at the delivery end of said wall and forming a continuation l thereof, means to produce suction at said suction ports, and means to deliver jets of drying medium through said nozzles thereby forming a stream of drying medium which flows over said wall longitudinally of the web and over said delivery section and on which the web is floatingly conveyed through said space and over the delivery section, portions of said stream being drawn downwardly through the suction ports and portions flowing outwardly through said open sides whereby there is set up within said-stream currents of drying medium which apply to the web a corrective force in a lateral direction whenever saidweb tends to move sideways in said space. Y

3. An apparatus for drying web material comprising a wall forming the bottom of a drying space which is open at its delivery end and through which space the web material may pass,

saidwali having a curved delivery section connected thereto at the'delivery end of said spaceand forming a continuationthereof, and means to deliver jetsof drying medium through said wall thereby toform a stream of drying medium which flows over the wall and over the delivery section, said .stream supporting the web while passing through thedryingspace and also while flowing over the delivery section.

.4. An apparatus for drying web material having a wall forming the. bottom of an elongated drying space which is openand unobstructed at its longitudinal sides and through which the web may pa'ss, said wall having a plurality of nomles for delivering the drying medium against .the

under face of the-web, which nozzles extend from one side to the other of said spaces and also having suction ports interspersed with the nozzles and situated in a row along the center line of said 1 drying space, thedimension of the suctionports in a direction transversely of the web being only a fraction of the corresponding dimension of the nozzles; means-to produce suction at said suction ports, means to deliver Jets of drying medium through said nozzles thereby forming a stream of drying medium flowing through said space in the direction of the length or the web on which the web is floatingly conveyed, and means for directing drying medium against the upper face of the web to maintain it in proper spaced relation with said bottom wall, portions of said stream o! drying medium being drawn downwardly through the suction ports and portions flowing outwardly through said open sides whereby there is set up within said stream currents oi drying medium which apply to the web a corrective force in a lateral direction whenever the web tends to move sideways in said space. I I

5. The method of drying web material by means of gaseous drying medium which consists in floatingly conveying the web material through a drying space by a stream of gaseous drying medium flowing through said space from one end to the other, and establishing in said stream of drying medium currents which tend to hold the web from sideways movement.

6. 'The method of drying web material by means of gaseous drying medium which consists in floatingly conveying the web material through a drying space by a stream of gaseous drying medium gaseous drying medium which is flowing through said space irom one end to the other, and establishing in said stream currents which apply to the web a corrective force in a lateral direction when- 20 ever the web tends to move sideways in said space.

ARTHUR GAUTREAU. A

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