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Publication numberUS3753298 A
Publication typeGrant
Publication dateAug 21, 1973
Filing dateDec 17, 1971
Priority dateDec 17, 1971
Also published asCA961636A, CA961636A1
Publication numberUS 3753298 A, US 3753298A, US-A-3753298, US3753298 A, US3753298A
InventorsD Ely
Original AssigneeBeloit Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Web dryer
US 3753298 A
Abstract
A web dryer structure for thermal removal of moisture from a traveling web such as a web of paper coming from the press section of a paper making machine including a row of upper dryer drums and a row of lower dryer drums with the drums positioned to carry the web in a sinuous path successively between the upper and lower drums and the web wrapping the upper and lower surfaces of the drums respectively with upper and lower looped felts wrapping the web on the upper and lower surfaces of the drums with the felt guided by guide rolls which are shifted laterally of the spaces between the drums a distance in the direction of web movement so that the pockets formed between the felts and the drums are pressurized due to the induced flow of air by the traveling felts and the guide rolls pumping air through the felts.
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Description  (OCR text may contain errors)

United States Patent 1191 Ely [75] Inventor:

52 us. 01 34/116, 34/117, 34/123, 34/120 511 1111.01. F26b 13/06, F26b 13/16 [58] Field of Search 34/117, 166, 120, 34/111, 116, 123

56 References Cited UNITED STATES PATENTS 3,378,936 4/1968 Buss 34/116 3,325,909 6/1967 Clark 34/l.ll 3,191,312 6/1965 Allander 34/116 3,355,816 12/1967 McKie et al. 34/116 3,316,657 5/1967 Haywood 34/116 3,314,162 4/1967 Haywood 34/111 1111 3,753,298 1451 Aug. '21, 1973 Primary Examiner-John J. Camby Assistant Examiner-Henry C. Yuen Attorney- 1 1111, Sherman, Meroni, Gross 8; Simpson 5 7] ABSTRACT A web dryer structure for thermal removal of moisture from a traveling web such as a web of paper coming from the press section of a paper making machine including a row of upper dryer drums and a row of lower dryer drums with the drums positioned to carry the web in a sinuous path successively between the upper and lower drums and the web wrapping the upper and lower surfaces of the drums respectively with upper and lower looped felts wrapping the web on the upper and lower surfaces of the drums with the felt guided by guide rolls which are shifted laterally of the spaces between the drums a distance in the direction of web movement so that the pockets formed between the felts and the drums are pressurized due to the induced flow of air by the traveling felts and the guide rolls pumping air through the felts.

11 Claims, 1 Drawing Figure 1 WEB DRYER BACKGROUND OF THE INVENTION The invention relates to improvements in dryer drum structures for drying a traveling web and more particularly to a structure which is used for thermally drying a web suchas a continuous run of paper which is received at high speed from the press section of a paper making machine.

More particularly, the invention relates to the particular arrangement and guidance of the felts for supporting theweb on the drum so that the web is supported at all locations of its travel and air pressure is induced in the pockets between the web and the drum so that the paper machine can operate at very high speeds without flutter of the Web.

In the dryer section of a thermal dryer, such as for a paper machine, the moisture bearing web is received from the press section of the machine and is directed along a serpentine path in wrapped relation with a plurality of steam heated dryer drums. These drums are usually arranged in upper and lower rows with the drums staggered so that the paper web can pass back and forth and wrap the upper and lower drums with the moisture evaporating from the web as it is heated while in contact with the drum. To aid in the heat transfer from the drum to the web and to support the web on the drum, upper and lower looped felts are provided which wrap over the outer surface of the web while on the drum surface. Arrangements have been made for guiding the felts in their travel between the drums and efforts have been made to utilize such guides to increase the drying action on the felts.

However, in relatively high speed paper making machines, disadvantages have been encountered in that the unsupported web in its travel between the felts will flutter. To attempt to run the dryer section of the machine at a slower speed to avoid such flutter will, of course, require slowing down the entire machine. Further disadvantage has been encountered in that with improvements in other sections of paper making machine, the effectiveness and efficiency of the dryer section has not kept up in certain instances so that additionally large or long dryer section have to be provided to accomodate increases in capacity of the other section of the machine. Speed and space limitations have made the drying section a limiting factor in the paper machine capacity and its speed in certain structural designs. In an attempt to avoid flutter at high speeds of 3,000 feet per minute and over, attempts have been made to stretch the paper web, but this does not eliminate flutter and tends to break the traveling web. Natural flutter is caused by air pressure buildup from air traveling with the web and felts at high web travel speeds and difficulty in controlling the web even when supported by the felt over felt turns has been encountered.

lt isaccordingly a feature of the present invention to eliminate the disadvantages of structures heretofore available by providing an arrangement wherein the web is in contact with or in close running relation to the supporting felt at all locations. of its travel between upper and lower tiers of dryer drums.

Another feature of the invention is to provide felt support rolls in a positioned arrangement so that an induced buildup of air in the pockets between the felts and supporting rollers is avoided.

Other efforts to control the problems which have been encountered in structures heretofore available have been numerous and these have including positioning the drums very close together so as to shorten the sheet draw between dryers. This proves disadvantageous because of the difficulties in sheet threading and problems with the felts. Efforts to ventilate the pockets between the felts or to break up the air layers carried on the felts to prevent flutter have also been found to have difficulties at high rates of speed.

It is accordingly an object of the present invention to provide a machine which has a thermal dryer section which is capable of handling traveling webs at a high rate of speed such as from 3,000 to 4,000 feet per minute or more.

Another object is to provide a dryer wherein separate felt dryers are not needed. Further objects of the invention are to provide a thermal dryer embodying heated dryer drums wherein a web passing over the drums is supported at all locations of its travel by supporting belts and wherein an induced flow of air is created through the belts and the pockets to avoid web flutter causing air flows'from the pockets.

A still further object of the invention is to provide an improved structure for a dryer section of a paper making machine utilizing upper and lower dryer drums which permits the possibility of reconstruction of existing dryer sections without extensive relocation of parts and without relocating the dryer drums and with a minimum of reconstruction.

Other objects, advantages and features will become more apparent including the equivalent structures and method from the teaching of the principles of the invention in connection with the disclosure of the preferred embodiments in the specification, claims and drawings in which:

DESCRIPTION OF THE DRAWINGS The single drawing of the application is a somewhat schematic end view illustrating the position, structure and operation of a mechanism in accordance with the principles of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A traveling web W is received from the left end of the drawing traveling to the right and the web may be a traveling paper web received from the last press section of a paper making machine. The web is carried by looped belts 20 and 21, which are of cotton, plastic or other material sufficiently porous to permit the escape of steam and the flow of air therethrough and which will be referred to hereinafter as felts. The web is received on a traveling lower felt 21. A similar upper felt 20 is led onto the lower felt with the web therebetween. The lower felt is trained over a guide roller 23 and the upper felt over a guide roller 35.

The web is led by the felts through the dryer drums which are arranged in an upper row formed by the drums 12, 13, 14 and 15 and a lower row 16, 17 and 18 with the dryer drum being of the conventional steam heated type and being laterally offset from each other.

The upper felt wraps the web over the upper surfaces of the upper drums and the lower felt wraps the web over the lower surfaces of the lower drums.

The upper felt 20 is guided between the upper rolls by a series of felt guide rolls 26, 27 and 28. Similarly.

the lower felt 21 is guided between the lower dryer drums by a series of guide rolls 24 and 25. The looped felts have adequate guiding and tensioning rolls which are omitted from the drawing for the sake of clarity. The felts also may be provided with felt cleaners and felt dryers.

As will be seen from the drawing, the guide rolls 26, 27 and 28 are positioned between respective pairs of lower dryer drums. Similarly, the felt guide rolls 24 and 25 are positioned between respective pairs of upper dryer drums.

The felt guide rolls are also arranged so that the guide rolls for the lower felts are positioned higher than the guide rolls for the upper felts. In the arrangement shown, considering the drum 12 to be the first upper drum and 13 the second upper drum, the first guide roll 26 is positioned below the second upper drum 13. Considering 16 to be the first lower dryer drum and 17 to be the second lower dryer drum, the first guide roll 24 is positioned above the second dryer drum 17.

As shown in the drawing, the web W travels over the first upper dryer drum 12 supported on the lower felt 21 and is guided to wrap the first lower dryer drum 16. A heated dryer means 34 is positioned outside of the belt above the upper drum 12. The web then travels upwardly in a run 21a of the lower felt to where it is transferred to the upper felt 20 at the location of the felt guide roll 26. Air moving with the web W on the felt run portion 21a is forced into the triangular space indicated at A and builds up between the felt and web as they wrap the felt roll 26. The geometrical relationship between the felt and felt roll 26 indicated at B combined with the direction of travel and rotation of the felt and roll 26, respectively, is such that a subatmospheric condition will be created at B which will draw the air trapped between the felt and web through the felt into the space E thus avoiding any tendency of the web to flutter in its travel along the span indicated at 20a. Similarly, air moving with the web W on the felt run portion 20b is forced into the triangular space C and builds up between the felt and web as they wrap the felt roll 24. The subatmospheric condition created at D will draw the air trapped between the felt and web through the felt into the space D thus avoiding web flutter. This process is repeated at felt rolls 27, 25 and 28 thus providing for a stable and controlled web run through the dryer section.

Additionally, air flowing with the lower surface of the lower felt in its run 21a will induce an upward flow of air to pressurize the space 36 thereby causing a flow of air through the felt into the pocket 30 as indicated by the arrows. This flow of air aids in the transfer of the web from the lower felt run 21a to the upper felt 20a at the guide roll 26 so that the web will travel upwardly following the upper felt in its run 200. The pressure in the pocket 30 will support the web on the felt run 20a and the flow of air thorugh the felt in the upper portion of the felt run 21a tends to dry the felts. Moisture laden air is removed from the pockets 30, 31, 32 and 33 at the front and rear end portions thereof. The airflow pattern through the felt into the pockets is repeated at 32, 31 and 33 and through successive pockets not shown.

To further aid in the removal of air from the critical areas A,B,C and D the felt rolls 26, 27, 28, 24 and 25, as shown at 25, may be in the form of suction felt rolls comprising a perforate shell and an interior suction gland positionable for optimum air removal. Another solution to the problem of web flutter at high papermaking speeds has been presented in the co-pending application for patent Ser. No. 209205 of Elmer C. Crist filed concurrently herewith and the present invention is a specific improved form of the structure disclosed therein.

As will be observed with reference to FIG. 3 of the aforementioned application for patent by Elmer E. Crist, Ser. No. 209,205, the air carried on the felt run is forced into the triangular space defined by the felt run portion 10c and feltroll 19a. The air is forced through the felt and is trapped by the web W causing it to bulge and form a bubble causing causing a potentially unstable condition. I

In the arrangement of the present invention air carried on the web span 21a is forced into the triangular space defined by the web run portion 21a and roll 26. On the off-running side of the roll 26 a vacuum is cre ated which sucks the air through the felt from the underside of the web. No air bubbles are formed around the roll 26 and the web remains in a stable condition.

Similarily air carried on the feltrum portion 21a is carried into the pocket 36 and forced into the pocket 30 through the felt as indicated by the arrows thus preventing air buildup around the roll 24.

As will be observed, the web has been supported at all locations of its travel and there are no unsupported draws where flutter or uncontrollability can occur.

Also, the guide rolls are so positioned so that the induced flow of air not only aids in transferring of the web, but aids in drying of the felts. At high speeds, this induced flow of air is significant, and the conduits at the ends of the pockets can control the flow of air so that the pockets are slightly pressurized to aid in supporting the web on the felt after it has been transferred or they may induce an increased flow of air through the felt.

I claim as my invention:

1. A web dryer for the thermal removal of moisture from a traveling web comprising in combination,

a plurality of rotatably mounted upper dryer drums adapted to be heated to carry a web and evaporate moisture therefrom,

a plurality of rotatably mounted lower dryer drums adapted to be heated to carry the web and evaporate moisture thereform, said drums positioned to carry the web in a sinuous path passing successively between the upper and lower drums with the web wrapping their upper and lower surfaces respectively, upper and lower looped belts formed of a pervious material accommodating the escape of water vapor from the web and wrapping the web on the upper and lower surfaces of the upper and lower drums respectively, upper and lower belt guide rolls for the upper and lower belts respectively with one guide roll between each pair of adjacent drums for the upper drums and for the lower drums, said lower belt guide rolls positioned to carry the portion of the lower belt between adjacent lower drums into the spaces between said lower drums,

said upper belt guide rolls positioned to carry the portions of the upper belt between adjacent upper drums into the spaces between said upper drums and said guide rolls positioned laterally of said spaces in the direction of web travel and located to carry each of the belts to receive the web directly from the other belt as the web travels between the upper and lower dryer drums so that the web is supported for its travel between the lower and upper drums and so that the web wraps a greater surface area of the drum on the onrunning side than on the offrunning side and air layers building up between the web and the guide rolls are dissipated on the offrunning side of the guide rolls.

2. A web dryer structure for the thermal removal of moisture from a traveling web constructed in accordance with claim 1 wherein a flow of air is induced through the belts into the pockets between the lower belt and the upper drums and between the upper belt and the'lower drums for aiding in transfer of the web and drying of the belts 3. A web dryer structure for the thermal removal of moisture from a traveling web constructed in accordance with claim 1 wherein lead guide means is provided so that the upper belt travels in an upward path to the first upper drum and the first lower guide roll carries the lower belt to position the web in engagement with the upper belt as the web travels from the first lower to the second upper drum.

4. A web dryer structure for the thermal removal of moisture from a traveling web constructed in accordance with claim 2 wherein the air flows axially outwardly from the ends of said pockets.

5. A web dryer structure for the thermal removal of moisture from a traveling web constructed in accordance with claim 1 and including a lead guide for the upper belt directing it in a path onto the first upper drum with the lower belt then passing down over the first lower drum.

6. A web processing device for contioning a traveling web constructed in accordance with claim 1 wherein the guide rolls comprise a perforate shell and'a suction gland in said shell.

7. A web dryer structure for the thermal removal of moisture from a traveling web comprising in combination:

a plurality of rotatably mounted upper dryer drums adapted to be heated and carry a web and evaporate moisture therefrom,

a plurality of rotatably mounted lower dryer drums adapted to be heated to carry the web and evaporate moisture therefrom, said drums positioned to carry the web in a sinuous path passing successively between the upper and lower drums with the web wrapping their upper and lower surfaces respectively,

upper and lower looped belts formed of a pervious material accommodating the escape of water vapor from the web and wrapping the web on the upper and lower surfaces of the upper and lower drums respectively,

and upper and lower belt guide rolls positioned respectively between adjacent upper and lower drums training said belts between the upper and lower drums and positioned so that the web is in close running relation to the belts to be controlled by a belt in all positions of its travel between the upper and lower drums,

said guide rolls positioned so that the upper and lower belts wrap a greater arc of the upper and lower drums respectively on the onrunning side than on the offrunning side.

8. A web dryer structure for the thermal removal of moisture from a traveling web constructed in accordance with claim 7 wherein a flow of air is induced in the open spaces between the lower felt and upper drums and upper felt and lower drums.

9. A web dryer structure for the thermal removal of moisture from a traveling web constructed in accordance with claim 7 and including a heated dryer means positioned outside of the belt on the first upper dryer drum.

10. A web processing device for conditioning a traveling web comprising in combination,

an upper drum adapted to carry a web,

a lower drum adapted to carry a web,

said web wrapping the upper and lower surfaces of the upper and lower drums respectively,

upper and lower belts wrapping the web drums,

upper and lower belt guide rolls for the upper and lower belts respectively, with one guide roll between each pair of adjacent drums for the upper drums and for the lower drums,

said guide rolls positioned to guide the portions of the upper and lower belts between adjacent pairs of drums toward each other into close running relationship between the drums so that the web is controlled for its entire travel between the upper and lower drums,

said belts defining runs for the web between upper and lower drums with one belt defining one portion of the run and the other belt defining another portion of the run with said portions being at an angle to each other,

said guide rolls positioned so that as the web is carried in the first portion of its run it is turned into the second portion of its run at an angle in the direction of the supporting belt so that an air layer carried on the belt tends to be removed by the pumping action of the offrunning side of the guide roll.

11. A web processing device for conditioning a traveling web constructed in accordance with claim 10 wherein the guide rolls are positioned so that the web wraps a greater angle of the drum on the onrunning side than on the offrunning side.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3191312 *Apr 16, 1962Jun 29, 1965Svenska Flaektfabriken AbMethod of uniformly moistening paper and like hygroscopic web material
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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4000035 *May 9, 1974Dec 28, 1976J. M. Voith GmbhMachine for drying webs, including suction and heat-contact cylinders
US4251928 *Feb 5, 1979Feb 24, 1981Asten Group Inc.Metal impregnated dryer fabric
US4485567 *Sep 29, 1982Dec 4, 1984Beloit CorporationDryer felt run
US4815220 *Jul 18, 1986Mar 28, 1989Beloit CorporationWeb transfer apparatus
US4953297 *May 13, 1987Sep 4, 1990Valmet Paper Machinery Inc.Method of and device for pocket ventilation in the drying section of a paper machine, in particular for high-speed paper machines
US4972608 *Oct 25, 1989Nov 27, 1990Valmet Paper Machinery Inc.Multi-cylinder dryer for a paper machine with supported draw of web
US5475934 *Feb 19, 1993Dec 19, 1995Valmet Paper Machinery, Inc.Method and device for ensuring the run of the web in the multi-cylinder dryer of a papermachine
US5560123 *Feb 19, 1993Oct 1, 1996Valmet Paper Machinery Inc.Method and device for ensuring the run of the web in the multi-cylinder dryer of a papermachine
US5586397 *Apr 18, 1994Dec 24, 1996Valmet CorporationDryer sections of a paper machine
US5630285 *Jan 30, 1996May 20, 1997Valmet CorporationMethods for drying a paper web
US5661911 *Mar 26, 1996Sep 2, 1997Valmet CorporationDryer section of a paper machine
US5720109 *Feb 17, 1995Feb 24, 1998Valmet CorporationMethod for drying a paper web
US5756156 *Aug 29, 1996May 26, 1998Valmet CorporationMethod for producing surface-treated paper and dry end of a paper machine
US5775001 *Dec 23, 1996Jul 7, 1998Valmet CorporationDryer sections of a paper machine
US5792318 *Jul 20, 1997Aug 11, 1998Mancini; RalphMethod to stabilize sheet between press section and dryer section of a paper-making machine
US5862613 *Apr 28, 1998Jan 26, 1999Valmet CorporationPaper machine and methods for drying a paper web
US6126787 *Mar 17, 1998Oct 3, 2000Valmet CorporationDry end of a paper machine
US6193840Aug 26, 1999Feb 27, 2001Valmet CorporationMethod for producing surface-treated paper
US6260287 *Apr 27, 2000Jul 17, 2001Raffaele ManciniWet web stability method and apparatus
DE3146936A1 *Nov 26, 1981Jun 24, 1982Valmet OyVerfahren in einem papiermaschinen-reihentrockner oder dergleichen
DE3508964A1 *Mar 13, 1985Sep 26, 1985Valmet OyVerfahren und vorrichtung zur unterstuetzung der bahn in schnellaufenden papiermaschinen
DE3790947C2 *May 13, 1987May 9, 1996Valmet Paper Machinery IncPocket ventilation for fast paper machine
DE3818600A1 *Jun 1, 1988Dec 29, 1988Valmet Paper Machinery IncProcess and device in a paper machine cylinder-dryer in which a two-fabric path is used
DE4009287A1 *Mar 22, 1990Oct 4, 1990Valmet Paper Machinery IncTaschenbelueftungsverfahren und -vorrichtung
DE4009287B4 *Mar 22, 1990Feb 24, 2005Metso Paper, Inc.Verfahren und Vorrichtung zum Trocknen einer feuchten Papierbahn in einer Papiermaschinen-Trockenpartie
DE4018882A1 *Jun 13, 1990Dec 19, 1991Voith Gmbh J MPaper-making drying section - has structured path for paper web and blankets between the guide rollers in a row between two banks of drying cylinders
EP0071639A1 *Feb 8, 1982Feb 16, 1983Weyerhaeuser CompanyHigh speed paper drying
EP0726353A2Nov 20, 1995Aug 14, 1996Valmet CorporationMethod for producing surface-treated paper and dry end of a paper machine
EP0916763A2Nov 20, 1995May 19, 1999Valmet CorporationMethod for producing surface-treated paper and dry end of a paper machine
WO1987006635A1 *Apr 21, 1986Nov 5, 1987Beloit CorporationDryer felt run
WO1988008898A1 *May 13, 1987Nov 17, 1988Valmet Paper Machinery Inc.Method of and device for pocket ventilation in the drying section of a paper machine, in particular for high-speed paper machines
WO1994019535A1 *Feb 19, 1993Sep 1, 1994Valmet Paper Machinery Inc.Method and device for ensuring the run of the web in the multi-cylinder dryer of a papermachine
WO2000079047A1 *Jun 16, 2000Dec 28, 2000Asten AgMethod and device for the improved drying of a paper web
Classifications
U.S. Classification34/116, 34/117, 34/123, 34/120
International ClassificationD21F1/00, D21F5/02, D21F5/04, F26B13/08
Cooperative ClassificationF26B13/08, D21F5/02
European ClassificationD21F5/02, F26B13/08