US2286595A - Apparatus for drying webs of paper regenerated from cellulose derivatives - Google Patents

Description

June 16, 1942. ER

APPARATUS FOR DRYING WE'BS OF PAPER REGENERATED FROM CELLULOSE DERIVATIVES Filed March 10, 1938 2 Sheets-Sheet -l .Q ooooo Q. Q Q E m w I l m INVENTOVR Ernest B LEIBLER M M M O .OOOOOOO. .OOOOOOOOOOOOOOOOOO....OOOOOOOOOO...

ATTO R N EY 2,286,595 RATED 2 Sheets-Sheet 2 June 16, 1942. E. BLEIBLER APPARATUS FOR DRYING WE'BS 'OF PAPER REGENE FROM CELLULOSE DERIVATIVES Filed March 10, 1938 INVENTOR E rnest BLEIBLER BY ATTORNEY.

Patented June 16, 1942 APPARATUS FOR DRYING WEBS OF PAPER REGENERATED FROM CELLULOSE DERIV- ATIVES Ernest Bleibler,-Ghent, Belgium,

Application March 10, 1938, Serial No. 195,049 In Belgium March 11, 1937 7 Claims. (CI. 34-60) The invention relates to apparatus for drying webs, foils, sheets, films, bands, strips, pellicles, or the like of paper, preferably transparent paper regenerated from aqueous solutions of cellulose derivatives such as viscose, cuprammonium cellulose, or others. In the following. specification and claims all of these goods are shortly designated as webs. Drying of such webs is a highly According to an embodiment of this invention remoistening is efiected by conducting or diverting to the remoistening zone from below and within said chamber vapor saturated air from the region ofhighest vapor saturation of the ventilating air .within the chamber.

Another object of this invention is to avoid es- I caping of ventilation air from the ventilation delicate process requiringcontinued attention in view of the sensitivity of the web against mechanical damage andin view of the fact that the dried end-product should contain a certain and limited amount of humidity in order to preserve its elasticity and to avoid brittleness and tackiness which might cause foils or sheets lying adjacent to each other to adhere one to the other during their storage.

It is a first object of this invention to arrange the drying apparatus to allow the operator full access to, and survey of the upper surface of the web while it is being fed along and through the drying apparatus, unrestricted by any drying or ventilation chamber or its structural parts. This object in mind, according to this invention, a ventilation chamber is arranged which is exclusively arranged within the space underneath the heated rollers of a roller train which train supports and feeds the web along and through the drying apparatus, the webthus forming a ceiling of, and a closure tothat ventilation chamber.

It is another object of this invention to render the operation of the drying apparatus highly eilicient and economic in respect of heat consumption by allowing the web to leave the roller train at a degree of inherent moisture which excludes any liability of the-web to getting brittle,

tacky or sticky, or unsightly.

It is a further object of this invention to conduct the drying process with a view to first fully drying the web and then remoistening it during one and the same procedure and travel through and along the drying apparatus, thus obviating the necessity of separate processes for drying the web and then re-introducing the desired degree of moisture.

A still further object of this invention is to arrange supply, withdrawal, and circulation of the ventilating air within the ventilation chamand ber and from below the web so as to result in a I drying apparatus or highly favorable mechanical, thermal, and economical conditions by supplying fresh air from both sides to the drying apparatus,

one part being supplied at the entry of the web into the apparatus, the other part at or near the zone of remoistening.

gaps between the roller train and its supporting side frames, thus blocking the escape of hot and humid air to the outside and especially to the working and surveying place of the operator and thus reducing to a great extent the inconvenience and the strain of his work.

Further objects of the invention will appear from the following description and the drawings afiixed thereto.

In the drawings aflixed to my specification and forming part thereof, an emobodiment of my invention is illustrated byway of example.. It will be readily understood however, that my invention is by no means limited tothis construction and that the scope of my invention andthe ambit ofmy appended claims extend toany construction incorporating the broad my invention.

In the drawings: v I

Fig. 1 shows a longitudinal elevation, partly in section, of a drying apparatus constructed in accordance with my invention,

Fig. 2 is a plan view of a ventilation chamber,

Fig. 3 is a vertical cross-section, in an enlarged scale, along line 33 of Figs. 1 and 2. Fig. 4 is a vertical section along line 4"4 of Fi .5, and i Fig. 5 is'a longitudinal section along line 5 5 of Fig. 4 on an enlarged scale of'the heat recup- 'erator of Figs. 1 and 2.

Referring to the drawings, 11, 12 is a rolle train composed of an upper tier or rollers, and a lower tier of rollers l2 supported by side frames 26, 21, which may be covered or coated by insulating material as indicated at 30 and 3 l'. The rollers II, I! support and feed the web l3 to be dried through and along the roller train. The rollers principle underlying may be heated by hot air, steam, hot water, or other liquid or medium, by supplying the heating medium, by means of pipes I4, to the hollow interior of the rollers at one side and withdrawing the medium at the other side through pipes l5, or vice versa. The rollers may be driven in any suitable manner, for instance by gearing l6, l1, or by the forward motion of the material to be dried. The web I3 is fed to the rollers of the roller train at the entry side 2| by means of the feed rollers -and is delivered to the wind-up reel 23 at the exit end 22 of the web. The ventilation chamber 25 is confined to the space underneath the rollers ll, l2 and web I3, and is enclosed between the side frames 26, 21 on the one hand, and between the rollers or web and the floor or base structure 28 on the other hand.

Two ventilating systems are allotted to the ventilation chamber, each consisting of ,a ventilator and air-ducts. Fresh air is supplied by ventilator 33, which may be driven by electromotor 34. The air is conducted through channel 'arranged, parallel to and below the ventilation chamber, within the floor. Channel 35 opens at 36 and 31 to the ventilation chamber 25, the openings being controlled by adjustable valves or flaps 38. The discharging ventilating system consists of ventilator 40, driven by electromotor 4|, and

the exhaust channel 42 extending within channel 35 and opening at 43 and 44 into the ventilation chamber; the openings 43 and 44 being likewise controllable by means of adjustable flaps 45. The wall of channel 42 is of heat conductive material so that fresh air, entering channel 35, may be preheated by the heat of the discharged air, and transferred to it through the heat conductive wall of channel 42. The exhaust heat will be easily and effectively exchanged between both currents. The recuperator may be provided with a separator or trap for assembling the condensed water, not shown in the drawings.

The operation of the apparatus is as follows:

The wet web l3 issuing from the baths or tanks and entering at 2| is conveyed through the roller train and finally wound up on reel 23 at the end 22 of the roller train. The air within the chamber is circulated in each section by means of fans 61, passes through the jets 14, sweeps the lower surface of the web, and is then drawn back at the sides to and by the fans 61, as indicated by the arrows in Fig. 3. The air sweeping theweb will take up the heat and the vapor emanating from the web. The air within the ventilation chamber will thus become more and more saturated with vapor until, as is known, a maximum of saturation will be reached at a place lying between about a third and a half of the length of the roller train or airchamber respectively. At that place, which may be at opening 43, the saturated air is discharged by means of ducts 42 and ventilator 40, and the remainder of the saturated air will be withdrawn through opening 44. Fresh air for replacing the withdrawn saturated air is admitted at the entry side of ventilation chamber 25 through opening 36 and may be additionally supplied at the last section or sections of the roller train at 31, from which point fresh air will flow to either side of the air chamber as indicated by the arrows in Fig. 1. Other parts of fresh air may enter the ventilation chamber together with the web and at the end of the ventilation chamber where the web leaves the roller train. I

Now, experience shows that the goods which preferably come into consideration for the apparatus according to this invention, namely transparent cellulosic papers regenerated from viscose or other aqueous solutions of cellulose derivatives, when immediately dried to their desired contents of humidity, will be tacky or sticky and will tend to adhere one to the other; when web or sheet with air conveyers or fans 61 and nozzle 12; and

the fans may be driven by any convenient drive as indicated at 68. The nozzles 12 are provided with guiding surfaces 13 and jet slots 14 in their upper surface. A heat recuperator may be arranged within both conduits 35, 42 in addition to the heat recuperating arrangement of ducts 35 and 42 for interchanging heat between both conduits and for recovering the heat which may be finally contained within the air to be discharged.

The heat recuperator 11 may be of any conyentIonaltype and is shown in Figs. 4'and 5 on anenlarged scale.

A group of parallel sheets 88 of heat conducting material, for instance of metal, is arranged within the duct 35. The sheets are spaced from each other by means of alternately arranged vertical spacing bars 8| and horizontal spacing bars 82.

I These sets of spacing bars thus form groups of horizontal ducts 83 and of vertical ducts 84, the

one kind of ducts being imbedded between the are inserted into, and connected with-duct 35,

' whereas the horizontal ducts 83 are inserted into,

ducts of the other kind. The vertical ducts 84 'as to be interrupted just at the pointwhere the desired degree of humidity is reached.

A better result has been obtained by fully drying the cellulose paper-and to store it in an airconditioned storage room. The humidity and temperature of this 'room may then be controlled, so that the foils will retake the humidity which had been'removed in excess of the desired amount. This operation may be easily controlled and the tendency of the foils to adhere one to the other will be greatly reduced; a draw-back of this procedure being however the long time, some days oreven some weeksfwhich ithecessitates. If the goods are needed immediately after having been produced, they will be brittle and will give cause to disturbances when being cut or otherwise handled. r

When trying to remoisten the web by direct supply of water vapor, other drawbacks are encountered with, as the web avidly resorbs the water and thus the procedure cannot be controlled and moreover, this manner of restoring humidity to the film is disastrous in view of heat economy.

. These drawbacks are fully eliminated by applying the system as will now be described.

In order to produce, under economical conditions regarding the heat applied to the system, a web which leaves the drying apparatus with the desired degree of humidity without being tacky the web is first completely dried and then remoistened from below during one and the same process during its uninterrupted travel throughand alongone and the same drying apparatus and above the same drying chamber.

To this end, a current of saturated air which has been diverted downwards from the zone of high or highest saturation in the ventilation chamber is supplied from below to the last section or sections of this chamber and is used for re-' on theione hand and brittle on the other hand, a

producing fresh ventilating air, a duct connectedwith said means for withdrawing the moist ventilating air, said ventilating chamber having at least one inlet from said first named duct and at moistening the web during its travel through the last section or sections of the ventilation chamber.

In order to remove the great quantity of water which is to be evaporated from the web, a great quantity of air is used which is to be saturated by the vapor emanating from the web, and to be heated, through the intermediary of the web, by the rollers, as high as possible, and which is then withdrawn. This air before being withdrawn is highly appropriate for remoistening the web which had formerly been completely dried. This highly saturated air will react readily and may thus be used in the sam apparatus so that the disadvantages will be avoided otherwise resulting from difliculty of control and deficiency of heat economy when introducing watervapor directly.

In the embodiment illustrated in the drawings, the last roller train section 66 is used for the purpose of remoistening the web. Highly saturated air from the zone of high air saturation is drawn to the last section lili, by means of the least one outlet into said last named duct; both said ducts being arranged underneath said ventilation chamber within said base structure and opening from underneath into said ventilating chamber by means of said inlet and said outlet respectively; at least one air mover and a nozzle both being located within said chamber between said inlet and said outlet for circulating said ventilating air within said chamber and directing it to sweep over the lower surface of sad web.

2. An apparatus for drying webs of paper regenerated from an aqueous solution of cellulosev derivatives, including a base structure, side frames on said base structure, a roller train supported by said side frames, said roller train for supporting and feeding the web through and along said apparatus; a ventilation chamber arranged exclusively below said web and within the space enclosed by said roller train, said side frames and said base structure; a ventilating air generating device for generating a current of ventilating air within and longitudinally of said ventilating chamber, and a ventilating air disfans 61 of this section, through the ducts 49,

and openings 5|, 53 and 52, 54 respectively. The passage through the ducts and thus'the degree of remoistening may be controlled by means of the above mentioned flaps 55. -The remoistening tributing device for circulating said current of ventilating air within and transversely of said ventilating chamber and for directing ventilating air to sweep .over the lower surface of said web;

said ventilating air generating device including air is admixed to the air circulated within section 66.

\ Volume, pressure, and velocity of supply and discharge air currents may be controlled bycontrolling the working conditions of the ventilators 33 and I0 and the adjustment of the flaps 38 and e 45 respectively.

In a preferred embodiment of the invention these controlling means will be regulated so as to establish within the ventilation chamber a small depression with regard to the ambient air and thus to avoid heat losses by discharge of the ventilation air to the outside through the gaps 80, 8| between the ends of the rollers ll, l2 of the roller train and the side frames 26, 21 respectively; to allow, moreover, the ambient air to be drawn through gaps 80, 8| into the ventilation chamber. As heat and vapor are withdrawn from the lower surface of the web, the space above the rollers will be substantially free from any emanating heat and vapor and the c'onvenience and supervision of operation will be increased to a considerable extent, the more as the space above the rollers is readily accessible due to the avoidance of any structural parts.

of the ventilation chamber which, according to this invention, has been confined to the space underneath the roller train.

I claim:

1. An apparatus for drying webs of paper regenerated from aqueous solutions of cellulose derivatives, including abase structure, side frames on said base structure, a roller train supported by said side frames, said roller train for supporting and feeding the web through and along said apparatus; a ventilation chamber arranged exclusively below said web and within the space enclosed by said roller train, said side means for producing a current of fresh ventilating air, means, for discharging the moist ventilating air from said chamber, said ventilating cham- -ber having at least one inlet and one outlet spaced a substantial distance apart from each other, ducts connecting both said means, respectively, to said inlet and said outlet of said ventilating chamber; said ventilating air distributing device including at least one fan and one nozzle both within said chamber.

3. An apparatus for drying websof paper regenerated from aqueous solutions of cellulose derivatives, including a base structure,- side frames on said base structure, a roller train supported by said side frames, said roller train for supporting and feeding the web through and along said apparatus; a ventilation chamber arranged exclusively below said web and within the space enclosed by said roller train, said side frames and saidbase structure; a ventilating air generating device, said chamber having at least one inletand one outlet spaced at a substantial distance from said inlet; said ventilating air generating device including means for producing directing air of said current. ofventilating air to sweep over and transversely of the lower surface of said web.

4. An apparatus as set forth in claim .3, where-. in said ducts are arranged parallel to, and underneath, the ventilation chamber, co-axially, one within the other and separated from one another-by a wall of heat conductive material.

5, An apparatus for drying webs of pap r generated from aqueous solutions of cellulose derivatives, including a base structure, side frames on said base structure, a roller train supported by said side frames, said roller train for supporting and feeding the web through and along said apparatus; a ventilation chamber arranged exclusively below said web and within the space enclosed by said roller train, said side frames and said base structure; said chamber having at least one inlet and one outlet spaced at a substantial distance from said inlet; a ventilating air generating device; said ventilating air generating device including means for producing a current of fresh ventilating air longitudinally of said chamber between said inlet and said outlet, means for 'scharging the moist ventilating air from said chamber, a fresh air duct and a discharge air duct respectively connecting said inlet of said ventilating chamber to'said means for producing a current of fresh ventilating air and said outlet. to said means for discharging the moist ventilating air, both said ducts being arranged underneath'said roller train; a series of air movers and nozzles be ng provided in, and spaced longitudinally of, said chamber for directing air of said longitudinal current of ventilating air to sweep over and transversely of the lower. surface of said web, and means for supplying humid air to said web at a place located near the discharge end of said chamber and from below said'chamber' for remoistening said web; said fresh air duct having an additional opening into said chamber at said web remoistenin'g place.

6. An apparatus for drying webs of paper regenerated from aqueous solutions of cellulose derivatives, including a base structure, side frames on said base structure, a roller train supported 'by said side frames, said roller train forsupporting and feeding the web through and along said apparatus; a ventilation chamber arranged exclusively below said web and within the space enclosed by said roller train, said side frames and said base structure; said chamber having at least one inlet and one outlet spaced at a substantial distance from said inlet, a ventilating air generating device; said ventilating air generating device including means for producing a current of fresh ventilating air longitudinally of said chamber between said inlet and said outlet, means for discharging the moist ventilating air from said-chamber', a fresh air duct and a discharge air duct respectively connecting said for producing a current of fresh ventilating air and said outlet to said means for dischargin the moist ventilating air, both said ducts being arrangedunderneath said roller train; a series tance to a part of vapor saturated air from said chamber to said conduit, the other of said openings being arranged at a place locatednear the discharge end of said chamber-and adapted to redirect said part of vapor saturated air into said chamber for remoistening said web; said fresh air duct having an additional opening communicating with said ventilation chamber at a place in the vicinity of said saturated air redirecting opening of said remoistening conduit.

7. An apparatus for drying webs of paper regenerated from aqueous solutions of cellulose derivatives, including a base structure, side frames on said base structure, a roller train supported inlet of said ventilating chamber to said means by said side frames, said roller train for supporting and feeding the web through and along said apparatus; a ventilation chamber arranged exclusively below said web and within the space enclosed by said roller train, said side frames and said base structure; said chamber having at least one inlet and one outlet spaced at a substantial distance from said inlet; a ventilating air generating device; said ventilating air generating device including means for producing a current of fresh ventilating air longitudinally of said chamber between said inlet and said outlet,

means for discharging the moist ventilating air from said chamber, a fresh air duct and a discharge air duct respectively connecting said inlet of said ventilating chamber to said means for producing a current of fresh ventilating air and said outlet to said means for discharging the moist ventilating air; both said ducts being arranged underneath said roller train; a series of air movers and nozzles being provided in, and

spaced longitudinally of, said chamber for directing air of said longitudinal current of ventilating air to sweep over and transversely of the. lower surface of said web, said apparatus further including a remoistening conduit communicating with said ventilation chamber at a place at about one third to one half the chamber lengthcalculated from the web entry side of said chamber and opening into said chamber at a place located near the discharge end-of said chamber, said remoistening conduit and said fresh air and discharge air ducts being arranged parallel to the length direction of said ventilation chamber and underneath the floor of said chamber.

ERNEST BLEIBLER.

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