US3576078A - Paper drying process and apparatus - Google Patents
Paper drying process and apparatus Download PDFInfo
- Publication number
- US3576078A US3576078A US7815A US3576078DA US3576078A US 3576078 A US3576078 A US 3576078A US 7815 A US7815 A US 7815A US 3576078D A US3576078D A US 3576078DA US 3576078 A US3576078 A US 3576078A
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- US
- United States
- Prior art keywords
- dryer
- drums
- drying
- paper
- web
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000001035 drying Methods 0.000 title claims abstract description 29
- 239000004744 fabric Substances 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 5
- 238000005201 scrubbing Methods 0.000 claims description 6
- 230000035699 permeability Effects 0.000 claims description 5
- 239000000463 material Substances 0.000 abstract description 2
- 238000001704 evaporation Methods 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 3
- 239000000835 fiber Substances 0.000 description 2
- 230000001869 rapid Effects 0.000 description 2
- 239000002759 woven fabric Substances 0.000 description 2
- 229920000742 Cotton Polymers 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000010425 asbestos Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229910052895 riebeckite Inorganic materials 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
Images
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F5/00—Dryer section of machines for making continuous webs of paper
- D21F5/02—Drying on cylinders
Definitions
- An endwise flexible woven fabric belt or dryer felt has heretofore been conventionally associated with each of the series of dryer drums, that is, a dryer belt is arranged to press the web into heat exchange relationship with a peripheral portion of each of the dryer drums with the opposed sides of the paper web alternately embracing the drums in the respective upper and lower series.
- the evaporation rates obtained with present-day Can" type dryers or drying drums of the aforesaid class is about I to 2 pounds per hour per square foot. This can .be contrasted with drying rates of from about to about 40 pounds per hour per square foot obtained with the relatively large diameter Yankee" drums, the latter being characterized by a diameter of from about 9 to about 15 feet.
- This higher ratefor the Yankee dryers is partially due to better conduction of heat from the dryer shell to the adhering paper, but is mostly due to employment therewith of high velocity types of hoods which reduces the boundary layer filmof moist air to a minimum which thus increases mass surfaces. A considerable amount of heat is also transmitted to the sheet from this scrubbing" air.
- the paper sheet to be dried is carried over the surfaces of the dryer drums of said drying drums at the area where the paper web is caused to pass over said drums.
- the thickness of the boundary layer film can be reduced to approximately 0.020 inch
- the boundary layer in the open sheet draws in the neighborhood of 0.25 inch.
- the drying rate can be in the neighborhood of 8 pounds per hour per square foot representing a four-fold increase.
- the present invention is particularly useful in overcoming problems encountered in dryer sections as speeds are increased above 2,000 feet per minute and basis weight of paper is less than 26 pounds per 3,000 square feet.
- the arrangement is self-threading and avoids the problem of sheet flutter and windage which are becoming problems for high weight paper grades.
- the sheet is separated from the dryer surfaces by a porous fabric at all times. While this will decrease the transfer of heat from the drying drum to the sheet, this decrease can be compensated for by the scrubbing air. Moreover, in the drying of lightweight paper, overall drying ability is not critical.
- drying hoods of conventional character can be employed in the present invention
- porous dryer fabrics of varying permeability in a cross direction have been found particularly useful, such drying fabrics consisting of endless belts of flexible woven fabric whereof the warp threads are greater in number per linear inch adjacent the longitudinal edges of the belts and decrease in number therefrom in a crosswise direction towards the longitudinal center of the belt, whereby the humidity profile, during drying, is flattened to produce a more uniform drying across the paper machine width.
- the porous fabric between which the paper web is confined and carried about the drying drums can be composed of either conventional cotton or asbestos or synthetic fabric such as polyester fiber or nylon and wherein the cross threads may be monofilaments and the warp threads of spun fibers.
- a fragmentary portion of the dryer section of a paper making machine comprises a plurality of heated drying cylinders, drums or cans 10 arranged in horizontally disposed upper and staggered lower series with the paper web 11 conducted sequentially into contact with a drum in one of the series to a drum in the other of the series and then back to the first series and so on, as is conventional so that heat is passed to the paper web from the drum in altematedirections a plurality of times until the web is dried to the desired extent.
- the paper web 11 While the paper web 11 is being carried over the drying drums in the manner aforesaid, it is conducted thereover between the porous fabrics 12 and 13 which are in the form of endless belts usually in separate pairs, which eliminate sheet marking due to the fabric contour or a series of pairs of fabrics operating as separate sections, the speeds of which can be adjusted to allow for stretch or shrinkage, one going about the upper cylinders and one going about the lower cylinders, with conventional tensioning by intermediate pocket rolls (not shown) which guide the fabrics 12 and 1.3 in its passage about the drying cylinders 10.
- a driving hood such as that shown at either l4, 15 or 16 of FIG. 1. While three different types of drying hoods are illustrated, it will be understood that generally one type of drying hood will be employed in a single dryer section and that hoods are similarly provided for the lower row of drying drums in inverted! position. These dryer hoods embrace about one-half of the periphery of the drying cylinders and have an arcuate top wall 17 as shown in the dryer 14, or the angular wall 18 for the dryer 15, or the composite wall 19 for the dryer 16.
- An air supply is introduced at a high velocity to the various drying hoods such as for example into the supply conduit 20 and through the hood 14 wherein a turbulent flow is induced to the air supply be means of the undulating member 21 and exhausted through the conduit 22.
- Air may be supplied to and exhausted from each an hood individually or two or more adjacent hoods may be connected to each other so that the air supply flows through a plurality of hoods.
- hood 15 air turbulence is provided by means of a convergent-divergent channel defined by the convergent and divergent components of the wall or or enclosure 18, and in the hood 16 a turbulent flow of air is provided to the supply plenum 23 and emitted through the exhaust plenum 24.
- hood designs per se are conventional and known to have the general effect of reducing boundary layer thickness.
- a plurality of drums rotating about horizontal axes arranged in upper and staggered lower series, a pair of porous fabric belts for embracing engagement with the opposed faces of said paper web and for conveying the web in spaced relationship to and alternately about said dryer drums, and dryer hood means embracing a plurality of said dryer drums in substantially the area where the paper web is carried thereover, said hoods including dryer air supply inlets and exhausts and means for causing turbulence of the air while passing said hoods and for subjecting the paper web to air scrubbing action through the meshes of said porous fabric.
- each of said drying drums include an embracing dryer hood.
- a method for drying a paper web in the dryer section of a paper making machine comprising a plurality of horizontally disposed rotatable dryer drums arranged in upper and staggered lower series the steps which comprise moving the paper web between a pair of porous fabric belts alternately about said dryer drums, and simultaneously subjecting the paper web to air scrubbing action through the meshes'of said porous fabric by impinging and flowing air thereover in a turbulent manner while being conveyed about said dryer drums.
Abstract
A process and apparatus for drying webs of newly formed paper material in the dryer section of a paper making machine having a plurality of rotatable dryer drums over which the paper web is guided in seriatim in heat exchange relationship while the web is disposed between open mesh dryer fabric endless belting and the web is scrubbed by air circulated through the meshes of the fabric while moving beneath hoods embracing the dryer drums.
Description
United States Patent Sherwood G. Holt Wisconsin Rapids, Wis. 7,815
Feb. 2, 1970 Apr. 27, 1971 Consolidated Papers, Inc. Wisconsin Rapids, Wis.
inventor Appl, No. Filed Patented Assignee PAPER DRYING PROCESS AND APPARATUS 4 Claims, 1 Drawing Fig.
US. Cl 34/23, 34/114, 34/159 Int. Cl F26b 3/00 Field of 34/23, 114, 159
[56] References Cited UNITED STATES PATENTS 1,844,658 2/1932 Holcomb Primary Examiner-Carroll B. Dority, Jr, Attorney-Gary, Parker, Juettner, Pigott and Cullinan ABSTRACT: A process and apparatus for drying webs of newly fonned paper material in the dryer section of a paper making machine having a plurality of rotatable dryer drums over which the paper web is guided in seriatim in heat exchange relationship while the web is disposed between open mesh dryer fabric endless belting and the web is scrubbed by air circulated through the meshes of the fabric while moving beneath hoods embracing the dryer drums.
so on. An endwise flexible woven fabric belt or dryer felt has heretofore been conventionally associated with each of the series of dryer drums, that is, a dryer belt is arranged to press the web into heat exchange relationship with a peripheral portion of each of the dryer drums with the opposed sides of the paper web alternately embracing the drums in the respective upper and lower series.
The evaporation rates obtained with present-day Can" type dryers or drying drums of the aforesaid class is about I to 2 pounds per hour per square foot. This can .be contrasted with drying rates of from about to about 40 pounds per hour per square foot obtained with the relatively large diameter Yankee" drums, the latter being characterized by a diameter of from about 9 to about 15 feet. This higher ratefor the Yankee dryers is partially due to better conduction of heat from the dryer shell to the adhering paper, but is mostly due to employment therewith of high velocity types of hoods which reduces the boundary layer filmof moist air to a minimum which thus increases mass surfaces. A considerable amount of heat is also transmitted to the sheet from this scrubbing" air.
In the arrangement of the present invention, the paper sheet to be dried is carried over the surfaces of the dryer drums of said drying drums at the area where the paper web is caused to pass over said drums.
Although the presence of this fabric tends to retard evaporation, the thickness of the boundary layer film can be reduced to approximately 0.020 inch In contrast to this, in a conventional system employing dense conveyor felts where almost no evaporation takes place over the dryer surface, the boundary layer in the open sheet draws in the neighborhood of 0.25 inch. With the arrangement of the present invention the drying rate can be in the neighborhood of 8 pounds per hour per square foot representing a four-fold increase. Although no increase in heat transfer from the cylinder to the sheet would be expected, this can also be increased by heating the scrubbing air in the hoods.
The present invention is particularly useful in overcoming problems encountered in dryer sections as speeds are increased above 2,000 feet per minute and basis weight of paper is less than 26 pounds per 3,000 square feet. Thus, in the present invention where the sheet is essentially sandwiched between two porous fabrics which follow the normal sheet runthrough the dryer section, the arrangement is self-threading and avoids the problem of sheet flutter and windage which are becoming problems for high weight paper grades.
With the present arrangement the sheet is separated from the dryer surfaces by a porous fabric at all times. While this will decrease the transfer of heat from the drying drum to the sheet, this decrease can be compensated for by the scrubbing air. Moreover, in the drying of lightweight paper, overall drying ability is not critical.
Perhaps one of the most valuable benefits from such a system is the tendencyof the dryer section to level out cross machine nonuniforrnities of moisture. While the present Can" dryers have this same tendency, however, this will be greatly increased by the high velocity air impingement employed in the present invention. Wetter spots, having better conductivity and better opportunity for vapor transfer, will dry more rapidly than the drier spots.
Although drying hoods of conventional character can be employed in the present invention, the use of porous dryer fabrics of varying permeability in a cross direction have been found particularly useful, such drying fabrics consisting of endless belts of flexible woven fabric whereof the warp threads are greater in number per linear inch adjacent the longitudinal edges of the belts and decrease in number therefrom in a crosswise direction towards the longitudinal center of the belt, whereby the humidity profile, during drying, is flattened to produce a more uniform drying across the paper machine width. The porous fabric between which the paper web is confined and carried about the drying drums can be composed of either conventional cotton or asbestos or synthetic fabric such as polyester fiber or nylon and wherein the cross threads may be monofilaments and the warp threads of spun fibers.
The process and apparatus of the present invention, its details and arrangements will be apparent from a consideration of the following specification and accompanying drawings, wherein the drawing diagrammatically illustrates the dryer section of a paper making machine embodying the present invention.
Referring to the drawings, a fragmentary portion of the dryer section of a paper making machine is illustrated and comprises a plurality of heated drying cylinders, drums or cans 10 arranged in horizontally disposed upper and staggered lower series with the paper web 11 conducted sequentially into contact with a drum in one of the series to a drum in the other of the series and then back to the first series and so on, as is conventional so that heat is passed to the paper web from the drum in altematedirections a plurality of times until the web is dried to the desired extent.
While the paper web 11 is being carried over the drying drums in the manner aforesaid, it is conducted thereover between the porous fabrics 12 and 13 which are in the form of endless belts usually in separate pairs, which eliminate sheet marking due to the fabric contour or a series of pairs of fabrics operating as separate sections, the speeds of which can be adjusted to allow for stretch or shrinkage, one going about the upper cylinders and one going about the lower cylinders, with conventional tensioning by intermediate pocket rolls (not shown) which guide the fabrics 12 and 1.3 in its passage about the drying cylinders 10.
As the paper sheet 11 is guided about the cylinder 10, it is further enveloped by a driving hood such as that shown at either l4, 15 or 16 of FIG. 1. While three different types of drying hoods are illustrated, it will be understood that generally one type of drying hood will be employed in a single dryer section and that hoods are similarly provided for the lower row of drying drums in inverted! position. These dryer hoods embrace about one-half of the periphery of the drying cylinders and have an arcuate top wall 17 as shown in the dryer 14, or the angular wall 18 for the dryer 15, or the composite wall 19 for the dryer 16. An air supply, either room temperature or preferably heated air, is introduced at a high velocity to the various drying hoods such as for example into the supply conduit 20 and through the hood 14 wherein a turbulent flow is induced to the air supply be means of the undulating member 21 and exhausted through the conduit 22. Air may be supplied to and exhausted from each an hood individually or two or more adjacent hoods may be connected to each other so that the air supply flows through a plurality of hoods.
In the hood 15 air turbulence is provided by means of a convergent-divergent channel defined by the convergent and divergent components of the wall or or enclosure 18, and in the hood 16 a turbulent flow of air is provided to the supply plenum 23 and emitted through the exhaust plenum 24. The foregoing various types of hood designs per se are conventional and known to have the general effect of reducing boundary layer thickness.
Although I have shown and described the preferred'embodiment of my invention, it will be understood by those skilled in the art that changes may be made in the details thereof without departing from its scope as comprehended by the following claims.
I claim:
1. In apparatus for drying a paper web in the dryer section of a-paper making machine, a plurality of drums rotating about horizontal axes arranged in upper and staggered lower series, a pair of porous fabric belts for embracing engagement with the opposed faces of said paper web and for conveying the web in spaced relationship to and alternately about said dryer drums, and dryer hood means embracing a plurality of said dryer drums in substantially the area where the paper web is carried thereover, said hoods including dryer air supply inlets and exhausts and means for causing turbulence of the air while passing said hoods and for subjecting the paper web to air scrubbing action through the meshes of said porous fabric.
2. The apparatus of claim 1 wherein each of said drying drums include an embracing dryer hood.
3. The apparatus of claim 1 wherein said dryer fabric belts are of varying permeability in the cross direction, the permeability being greatest adjacent its longitudinal center. i
4. In a method for drying a paper web in the dryer section of a paper making machine comprising a plurality of horizontally disposed rotatable dryer drums arranged in upper and staggered lower series the steps which comprise moving the paper web between a pair of porous fabric belts alternately about said dryer drums, and simultaneously subjecting the paper web to air scrubbing action through the meshes'of said porous fabric by impinging and flowing air thereover in a turbulent manner while being conveyed about said dryer drums.
Claims (3)
- 2. The apparatus of claim 1 wherein each of said drying drums include an embracing dryer hood.
- 3. The apparatus of claim 1 wherein said dryer fabric belts are of varying permeability in the cross direction, the permeability being greatest adjacent its longitudinal center.
- 4. In a method for drying a paper web in the dryer section of a paper making machine comprising a plurality of horizontally disposed rotatable dryer drums arranged in upper and staggered lower series the steps which comprise moving the paper web between a pair of porous fabric belts alternately about said dryer drums, and simultaneously subjecting the paper web to air scrubbing action through the meshes of said porous fabric by impinging and flowing air thereover in a turbulent manner while being conveyed about said dryer drums.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US781570A | 1970-02-02 | 1970-02-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3576078A true US3576078A (en) | 1971-04-27 |
Family
ID=21728261
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US7815A Expired - Lifetime US3576078A (en) | 1970-02-02 | 1970-02-02 | Paper drying process and apparatus |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US3576078A (en) |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3874997A (en) * | 1973-03-21 | 1975-04-01 | Valmet Oy | Multiple cylinder drier in a paper machine |
| DE2813933A1 (en) * | 1977-04-04 | 1978-10-12 | Valmet Oy | METHOD OF GUIDING A WEB IN THE DRY SECTION OF A PAPER MACHINE AND DRYING CYLINDER GROUP FOR PERFORMING THE METHOD |
| US4124941A (en) * | 1975-09-13 | 1978-11-14 | Hoechst Aktiengesellschaft | Process and additional devices of cylinder drying machines for the uniform drying of textiles |
| US4190964A (en) * | 1977-03-19 | 1980-03-04 | J. M. Voith Gmbh | Web drying section for paper machine |
| US4462868A (en) * | 1981-04-27 | 1984-07-31 | Kimberly-Clark Limited | Paper web drying apparatus having a hood with two sections |
| FR2568903A1 (en) * | 1984-08-08 | 1986-02-14 | Impact Systems Inc | DEVICE AND METHOD FOR PROCESSING A WEB OF MATERIAL |
| US5336373A (en) * | 1992-12-29 | 1994-08-09 | Scott Paper Company | Method for making a strong, bulky, absorbent paper sheet using restrained can drying |
| EP0653514A2 (en) * | 1993-11-15 | 1995-05-17 | Tokushu Paper Manufacturing Co. Ltd | Process and apparatus for drying sheet materials |
| US5647141A (en) * | 1993-11-15 | 1997-07-15 | Tokushu Paper Mfg. Co., Ltd. | Process and apparatus for drying sheet materials |
| US6154981A (en) * | 1998-04-30 | 2000-12-05 | Valmet Corporation | Method and apparatus for improving the drying capacity of a hood covering a yankee cylinder |
| US20070245588A1 (en) * | 2006-04-21 | 2007-10-25 | Haurie Osvaldo R | Cylindrical dryer having conduits for heating medium |
| US20070289156A1 (en) * | 2005-01-05 | 2007-12-20 | Rainer Kloibhofer | Device and method for producing and/or finishing a fibrous material |
| US20080005921A1 (en) * | 2005-01-05 | 2008-01-10 | Thomas Gruber-Nadlinger | Device and method for producing and/or finishing a web of fibrous material |
| US8127462B2 (en) | 2006-04-21 | 2012-03-06 | Osvaldo Ricardo Haurie | Cylindrical dryer having conduits provided within a plurality of holding plates |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1844658A (en) * | 1928-06-29 | 1932-02-09 | Fiberfraks Inc | Drier for paper-making machines |
-
1970
- 1970-02-02 US US7815A patent/US3576078A/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1844658A (en) * | 1928-06-29 | 1932-02-09 | Fiberfraks Inc | Drier for paper-making machines |
Cited By (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3874997A (en) * | 1973-03-21 | 1975-04-01 | Valmet Oy | Multiple cylinder drier in a paper machine |
| US4124941A (en) * | 1975-09-13 | 1978-11-14 | Hoechst Aktiengesellschaft | Process and additional devices of cylinder drying machines for the uniform drying of textiles |
| US4190964A (en) * | 1977-03-19 | 1980-03-04 | J. M. Voith Gmbh | Web drying section for paper machine |
| DE2813933A1 (en) * | 1977-04-04 | 1978-10-12 | Valmet Oy | METHOD OF GUIDING A WEB IN THE DRY SECTION OF A PAPER MACHINE AND DRYING CYLINDER GROUP FOR PERFORMING THE METHOD |
| US4462868A (en) * | 1981-04-27 | 1984-07-31 | Kimberly-Clark Limited | Paper web drying apparatus having a hood with two sections |
| FR2568903A1 (en) * | 1984-08-08 | 1986-02-14 | Impact Systems Inc | DEVICE AND METHOD FOR PROCESSING A WEB OF MATERIAL |
| US5336373A (en) * | 1992-12-29 | 1994-08-09 | Scott Paper Company | Method for making a strong, bulky, absorbent paper sheet using restrained can drying |
| EP0653514A3 (en) * | 1993-11-15 | 1996-02-14 | Tokushu Paper Manufacturing Co | Process and apparatus for drying sheet materials. |
| EP0653514A2 (en) * | 1993-11-15 | 1995-05-17 | Tokushu Paper Manufacturing Co. Ltd | Process and apparatus for drying sheet materials |
| US5647141A (en) * | 1993-11-15 | 1997-07-15 | Tokushu Paper Mfg. Co., Ltd. | Process and apparatus for drying sheet materials |
| US6154981A (en) * | 1998-04-30 | 2000-12-05 | Valmet Corporation | Method and apparatus for improving the drying capacity of a hood covering a yankee cylinder |
| US20070289156A1 (en) * | 2005-01-05 | 2007-12-20 | Rainer Kloibhofer | Device and method for producing and/or finishing a fibrous material |
| US20080005921A1 (en) * | 2005-01-05 | 2008-01-10 | Thomas Gruber-Nadlinger | Device and method for producing and/or finishing a web of fibrous material |
| US20070245588A1 (en) * | 2006-04-21 | 2007-10-25 | Haurie Osvaldo R | Cylindrical dryer having conduits for heating medium |
| US7614161B2 (en) * | 2006-04-21 | 2009-11-10 | Osvaldo Ricardo Haurie | Cylindrical dryer having conduits for heating medium |
| US8127462B2 (en) | 2006-04-21 | 2012-03-06 | Osvaldo Ricardo Haurie | Cylindrical dryer having conduits provided within a plurality of holding plates |
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