CA2325914A1 - An extended nip press section apparatus - Google Patents
An extended nip press section apparatus Download PDFInfo
- Publication number
- CA2325914A1 CA2325914A1 CA002325914A CA2325914A CA2325914A1 CA 2325914 A1 CA2325914 A1 CA 2325914A1 CA 002325914 A CA002325914 A CA 002325914A CA 2325914 A CA2325914 A CA 2325914A CA 2325914 A1 CA2325914 A1 CA 2325914A1
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- CA
- Canada
- Prior art keywords
- web
- felt
- extended nip
- press
- pick
- 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.)
- Abandoned
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Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/0209—Wet presses with extended press nip
- D21F3/0218—Shoe presses
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/0209—Wet presses with extended press nip
- D21F3/0218—Shoe presses
- D21F3/0227—Belts or sleeves therefor
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/04—Arrangements thereof
- D21F3/045—Arrangements thereof including at least one extended press nip
Abstract
An extended nip press section apparatus (10) is disclosed for pressing water from a formed web (W). The apparatus includes an elongated press shoe (14) and a vented backing roll (16) which cooperates with the shoe (14) for defining therebetween an extended nip (18) for the passage therethrough of the web. A bearing blanket (20) slidingly cooperates with the shoe (14) and extends through the extended nip, the blanket (20) being disposed between the web (W) and the shoe (14). A pick-up felt (22) extends through the extended nip for conveying the web to and through the extended nip. A press felt (24) extends through the extended nip such that the web (W) is disposed between the press felt (24) and pick-up felt (22) during movement of the web through the extended nip. The press felt (24) has a water permeability which is less than the water permeability of the pick-up felt (22) such that the web (W) predictably follows the press felt (24) rather than the pick-up felt (22) when the pick-up felt diverges relative to the press felt downstream relative to the extended nip, the arrangement being such that two-sidedness of the resultant pressed web (W) is inhibited.
Description
WO 98/54404 _ PCT/US98/06993 The present invention relates to an extended nip press section apparatus for pressing water from a formed web. More particularly, the present invention relates to an extended nip press section apparatus for inhibiting two-sidedness of the resultant pressed web.
In recent years, press sections for papermaking machines have become relatively complex. For example, some press sections include four or five press nips in order to maximize the dryness of the out-going pressed web and to minimize two-sidedness of the resultant sheet.
Two-sidedness is a problem which basically comes about as a result of water flowing more in one direction than another away from the web during passage of the web through a press nip. At least in theory, if the web is supported between two identical press felts and is guided between a pair of identical counter-rotating press rolls, the resultant web will have minimal two-sidedness. That is, both sides of the resultant web will have substantially the same surface characteristics thereon.
However, in practice, a pair of identical counter-rotating press rolls does not achieve maximum water removal, and it is very important to provide a press which removes as much water as possible in order to minimize the amount of steam required in a subsequent web drying section.
In recent years, press sections for papermaking machines have become relatively complex. For example, some press sections include four or five press nips in order to maximize the dryness of the out-going pressed web and to minimize two-sidedness of the resultant sheet.
Two-sidedness is a problem which basically comes about as a result of water flowing more in one direction than another away from the web during passage of the web through a press nip. At least in theory, if the web is supported between two identical press felts and is guided between a pair of identical counter-rotating press rolls, the resultant web will have minimal two-sidedness. That is, both sides of the resultant web will have substantially the same surface characteristics thereon.
However, in practice, a pair of identical counter-rotating press rolls does not achieve maximum water removal, and it is very important to provide a press which removes as much water as possible in order to minimize the amount of steam required in a subsequent web drying section.
Consequently, the aforementioned very large multiple nip presses have been built that require considerable maintenance due to the size thereof and the number of felts that require periodic changing.
In press sections of the aforementioned type, release rolls associated with such presses are often fabricated from granite.
Moreover, with the ever-increasing demand for higher production rates, such massive granite rolls must of necessity be rotated at a higher rotational speed. Accordingly, several fatalities have resulted from such granite rolls breaking apart under the aforementioned conditions.
Additionally, by pressing the web against the smooth surface of a granite or substitute granite release roll, the sheet attains a smooth surface on the roll side and a relatively rough surface on the felt side.
Such two-sidedness has typically necessitated the provision of an additional nip with the release roll on the oppasite side of the sheet in an attempt to correct the two-sidedness problem.
The aforementioned presses also typically include suction rolls which are expensive to maintain and which limit the potential loading capabilities of the nip and can cause shadow marking in the sheet.
Therefore, there is a need in the papermaking art for a simple, single nip press section which overcomes the aforementioned problems associated with prior art arrangements.
Therefore, it is a primary objective of the present invention to provide an extended nip press section apparatus that overcomes the WO 98/54404 _ PCT/US98/06993 aforementioned inadequacies of the prior art arrangements and which makes a considerable contribution to the art of pressing a web of paper to remove water therefrom.
Another object of the present invention is the provision of an extended nip press section apparatus which includes a press felt having a water permeability which is less than the water permeability of the pick-up felt so that the web predictably follows the press felt rather than the pick-up felt and which inhibits two-sidedness in the resultant pressed web.
Another object of the present invention is the provision of an extended nip press section apparatus which is extremely compact and which avoids the problem of rewetting the web.
Other objects and advantages of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description contained hereinafter, taken in conjunction with the annexed drawings.
Summary Of The Invention The present invention relates to an extended nip press section apparatus for pressing water from a formed web. The apparatus includes an elongate press shoe and a vented backing roll which cooperates with the shoe for defining therebetween an extended nip for the passage therethrough of the web.
A bearing blanket slidingly cooperates with the shoe and extends through the extended nip with the blanket being disposed between the web and the shoe.
In press sections of the aforementioned type, release rolls associated with such presses are often fabricated from granite.
Moreover, with the ever-increasing demand for higher production rates, such massive granite rolls must of necessity be rotated at a higher rotational speed. Accordingly, several fatalities have resulted from such granite rolls breaking apart under the aforementioned conditions.
Additionally, by pressing the web against the smooth surface of a granite or substitute granite release roll, the sheet attains a smooth surface on the roll side and a relatively rough surface on the felt side.
Such two-sidedness has typically necessitated the provision of an additional nip with the release roll on the oppasite side of the sheet in an attempt to correct the two-sidedness problem.
The aforementioned presses also typically include suction rolls which are expensive to maintain and which limit the potential loading capabilities of the nip and can cause shadow marking in the sheet.
Therefore, there is a need in the papermaking art for a simple, single nip press section which overcomes the aforementioned problems associated with prior art arrangements.
Therefore, it is a primary objective of the present invention to provide an extended nip press section apparatus that overcomes the WO 98/54404 _ PCT/US98/06993 aforementioned inadequacies of the prior art arrangements and which makes a considerable contribution to the art of pressing a web of paper to remove water therefrom.
Another object of the present invention is the provision of an extended nip press section apparatus which includes a press felt having a water permeability which is less than the water permeability of the pick-up felt so that the web predictably follows the press felt rather than the pick-up felt and which inhibits two-sidedness in the resultant pressed web.
Another object of the present invention is the provision of an extended nip press section apparatus which is extremely compact and which avoids the problem of rewetting the web.
Other objects and advantages of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description contained hereinafter, taken in conjunction with the annexed drawings.
Summary Of The Invention The present invention relates to an extended nip press section apparatus for pressing water from a formed web. The apparatus includes an elongate press shoe and a vented backing roll which cooperates with the shoe for defining therebetween an extended nip for the passage therethrough of the web.
A bearing blanket slidingly cooperates with the shoe and extends through the extended nip with the blanket being disposed between the web and the shoe.
4 _ PCTIUS98/06993 A pick-up felt extends through the extended nip for conveying the web to and through the extended nip.
A press felt extends through the extended nip such that the web is disposed between the press felt and the pick-up felt during movement thereof through the extended nip. The press felt has a water permeability which is less than that of the pick-up felt such that the web predictably follows the press felt rather than the pick-up felt when the pick-up felt diverges relative to the press felt downstream relative to the extended nip.
The arrangement is such that two-sidedness of the resultant pressed web is inhibited.
In one embodiment of the present invention, the elongate press shoe is hydrodynamic shoe, and in another embodiment of the present invention, the press shoe is a hydrostatic shoe.
In both embodiments of the present invention, the press shoe is disposed beneath the vented backing roll.
The vented backing roll has a cylindrical circumferential surface which defines a plurality of blind drilled holes according to one embodiment of the present invention.
In another embodiment of the present invention, the cylindrical circumferential surface of the backing roll defines a plurality of circumferential grooves.
The press section apparatus also includes a saveall which cooperates with the vented backing roll for collecting water removed from the web during movement of the web through the extended nip.
WO 98/54404 _ PCT/ITS98J06993 Additionally, the bearing blanket defines a plurality of grooves on a surface thereof which faces towards the press felt for assisting drainage from the extended nip.
The press section apparatus includes a steam box which is disposed on one side of the pick-up felt for applying steam to the web supported beneath the pick-up felt upstream relative to the press felt.
Additionally, a vacuum box is disposed on an opposite side of the web and pick-up felt relative to the steam box. The vacuum box is connected to a source of partial vacuum such that the steam from the steam box is drawn into the web. The arrangement is such that the viscosity of the water within the web is decreased by the application thereto of the steam so that the subsequent removal of the water from the web during passage thereof through the extended nip is facilitated.
The press felt in a specific embodiment of the present invention includes a base fabric and a permeability control layer which is disposed contiguously on one side of the base fabric.
Additionally, a layer of batt fibers is disposed contiguously relative to the permeability control layer such that the permeability control layer is disposed between the layer of batt fibers and the base fabric for inhibiting rewetting of the web downstream relative to the extended nip and for predictably assisting the web to follow the press felt rather than the pick-up felt downstream relative to the extended nip.
In a preferred embodiment of the present invention as shown in Fig.
12, the press section is inverted such that the pick-up felt is disposed between the shoe and the web.
WO 98/54404 _ PCT/US98/06993 Furthermore, the press felt extends through the extended nip with the press felt being disposed between the backing roll and the web so that the web is disposed between the pick-up felt and the press felt.
The backing roll can be either a plane roll or a vented roll and the bearing blanket can be a plane blanket or a grooved blanket or alternatively a blanket with blind drilled drainage holes defined therein.
Many modifications and variations of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description contained hereinafter, taken in conjunction with the annexed drawings. However, such modifications and variations fall within the spirit and scope of the present invention as defined by the appended claims.
Figure 1 is a side-elevational view of an extended nip press section apparatus according to the present invention for pressing water from a formed web;
Figure 2 is an enlarged view of the extended nip showing the press shoe as a hydrodynamic shoe;
Figure 3 is a similar view to that shown in Figure 2, but shows an alternative embodiment of the present invention in which the press shoe is a hydrostatic shoe;
Figure 4 is a perspective view of the vented backing roll showing the surface thereof defining a plurality of blind drilled holes;
Figure 5 is a similar view to that shown in Figure 4, but shows an alternative embodiment of the present invention in which the surface of the backing roll defines a plurality of circumferential grooves;
WO 98/54404 _ PCT/US98/Ob993 Figure 6 is a top plan view of a portion of the bearing blanket shown in Figure 1 showing a plain surface thereon;
Figure 7 is a similar view to that shown in Figure 6, but shows the surface of the bearing blanket towards the press felt defining a plurality of grooves for assisting drainage of water from the extended nip;
Figure 8 is an enlarged sectional view of the press felt showing the base fabric, control layer and the layer of batt fibers;
Figure 9 is a graph showing a pressure profile obtained using the apparatus according to the present invention;
Figure 10 is a graph showing another pressure profile achieved using the apparatus according to the present invention;
Figure 11 is a graph showing yet ~ another pressure profile obtained using the apparatus according to the present invention.
Figure 12 is a side elevational view of a preferred embodiment of the present invention; and Figure 13 is a side elevational view of an alternative embodiment of the arrangement shown in Figure 12.
Similar reference characters refer to similar parts throughout the various embodiments of the present invention.
Figure 1 is a side-elevational view of an extended nip press section apparatus, generally designated 10 according to the present invention, for pressing water, as indicated by the arrow 12, from a formed web W. The press section apparatus 10 includes an elongate press shoe 14 and a vented backing roll 16 which cooperates with the shoe 14 for defining therebetween an extended nip 18 for the passage therethrough of the web W.
WO 98154404 _ PCT/US98/06993 A bearing blanket 20 slidably cooperates with the shoe 14 and extends through the extended nip 18. The blanket 20 is disposed between the web W and the shoe 14.
A pick-up felt 22 extends through the extended nip 18 for conveying the web W to and through the extended nip 18. The pick-up felt 22 is disposed between the backing roll 16 and the web W such that the web W
is conveyed between the pick-up felt 22 and the blanket 20 during movement thereof through the extended nip 18.
A press felt 24 extends through the extended nip 18 and is disposed between the blanket 20 and the web W such that the web W is disposed between the press felt 24 and the pick-up felt 22 during movement of the web W through the extended nip 18. The press felt 24 has a water permeability which is less than the water permeability of the pick-up felt 22. The arrangement is such that the web W predictably follows the press felt 24 rather than the pick-up felt 22 when the pick-up felt 22 diverges relative to the press felt 24 downstream relative to the extended nip 18.
The arrangement is such that two-sidedness of the resultant pressed web W is inhibited.
Figure 2 is an enlarged side-elevational view of the elongate press shoe 14 showing the press shoe 14 as a hydrodynamic shoe.
Figure 3 is a similar view to that shown in Figure 2, but shows the press shoe 14A as a hydrostatic shoe.
As shown in Figure 1, the press shoe 14 is disposed beneath the vented backing roll 16.
WO 98/54404 _ PCT/US98/06993 Figure 4 is a perspective view of the vented backing roll 16 shown in Figure 1. As shown in Figure 4, the backing roll 18 has a cylindrical circumferential surface 26 which defines a plurality of blind drilled holes 28, 29 and 30.
Figure 5 is a similar view to that shown in Figure 4, but shows the vented backing roll 16B as having a cylindrical circumferential surface 26B
which defines a plurality of circumferential grooves 28B, 29B and 30B.
In the preferred embodiment of the present invention as shown in Figure 7 , the apparatus 10 includes a saveall 32 which cooperates with the vented backing roll 16 for collecting water 12 removed from the web W
during movement of the web W through the extended nip 18.
Figure 6 is an enlarged top plan view of the bearing blanket 20 showing the surface thereof as being a plain surface.
Figure 7 is a similar view to that shown in Figure 6, but shows an alternative embodiment of the present invention in which the bearing blanket 20C defines a plurality of grooves 34,35 and 36 on a surface thereof facing towards the press felt 24 for assisting drainage from the extended nip 18.
As shown in Figure 1, the apparatus 10 also includes a steam box 38 which is disposed on one side 40 of the pick-up felt 22 for applying steam to the web W supported beneath the pick-up felt 22 upstream relative to the press felt 24.
A vacuum box 42 is disposed on an opposite side 44 of the web W
and pick-up felt 22 relative to the steam box 38. The vacuum box 42 is WO 98/54404 _ PCT/ITS98/06993 connected to a source of partial vacuum 46 such that steam from the steam box 38 is drawn into the web W. The arrangement is such that the viscosity of water within the web W is decreased by the application thereto of the steam so that the subsequent removal of the water from the web W
during passage thereof through the extended nip 18 is facilitated.
Figure 8 is an enlarged sectional view of the press felt 24 which includes a base fabric 48 and a permeability control layer 50 disposed contiguously on one side 52 of the base fabric 48.
A layer of batt fibers 54 are disposed contiguously relative to the permeability control layer 50 such that the permeability control layer 50 is disposed between the layer of batt fibers 54 and the base fabric 48 for inhibiting rewetting of the web W downstream relative to the extended nip 18 and for predictably assisting the web W to follow the press felt 24 rather than the pick-up felt 22 downstream relative to the extended nip 18.
Figures 9, 10 and 11 are graphs showing various pressure profiles 56,58 and 60, respectively, obtained using the equipment according to the present invention.
In operation of the apparatus 10 shown in Figure 1, the web is transferred to the pick-up felt 22 such that the web is disposed beneath the pick-up felt 22.
Steam is applied through the web and is drawn into the web by the vacuum box 42.
The web sandwiched between the pick-up felt 22 and the press felt 24 is guided towards the extended nip 18 where water is removed WO 98154404 _ PCT/US98/06993 therefrom into the saveall 32, which cooperates with the vented backing roll 16 for collecting water 12 removed from the web.
Because of the permeability control layer 50 within the press felt 24, the web predictably follows the press felt 24 rather than the pick-up felt 22. Thereafter, the web is transferred from the press felt 24 into the downstream dryer section, generally designated 62.
In a preferred embodiment of the present invention as shown in Fig.
12, the press section is inverted such that the pick-up felt 22d is disposed between the shoe 14d and the web Wd.
Furthermore, the press felt 24d extends through the extended nip 18d with the press felt 24d being disposed between the backing roll 16d and the web Wd so that the web is disposed between the pick-up felt 22d and the press felt 24d.
The backing roll 16d can be either a plane roll as shown in Fig. 12 or a vented roll 16e as shown in Fig. 13. Also, the bearing blanket 20d can be a plane blanket or a grooved blanket or alternatively a blanket with blind drilled drainage holes defined therein.
The present invention provides a double felted extended nip press, which is particularly capable of pressing a news or fine paper sheet as dry as any of the traditional multi-nip press sections.
A press felt extends through the extended nip such that the web is disposed between the press felt and the pick-up felt during movement thereof through the extended nip. The press felt has a water permeability which is less than that of the pick-up felt such that the web predictably follows the press felt rather than the pick-up felt when the pick-up felt diverges relative to the press felt downstream relative to the extended nip.
The arrangement is such that two-sidedness of the resultant pressed web is inhibited.
In one embodiment of the present invention, the elongate press shoe is hydrodynamic shoe, and in another embodiment of the present invention, the press shoe is a hydrostatic shoe.
In both embodiments of the present invention, the press shoe is disposed beneath the vented backing roll.
The vented backing roll has a cylindrical circumferential surface which defines a plurality of blind drilled holes according to one embodiment of the present invention.
In another embodiment of the present invention, the cylindrical circumferential surface of the backing roll defines a plurality of circumferential grooves.
The press section apparatus also includes a saveall which cooperates with the vented backing roll for collecting water removed from the web during movement of the web through the extended nip.
WO 98/54404 _ PCT/ITS98J06993 Additionally, the bearing blanket defines a plurality of grooves on a surface thereof which faces towards the press felt for assisting drainage from the extended nip.
The press section apparatus includes a steam box which is disposed on one side of the pick-up felt for applying steam to the web supported beneath the pick-up felt upstream relative to the press felt.
Additionally, a vacuum box is disposed on an opposite side of the web and pick-up felt relative to the steam box. The vacuum box is connected to a source of partial vacuum such that the steam from the steam box is drawn into the web. The arrangement is such that the viscosity of the water within the web is decreased by the application thereto of the steam so that the subsequent removal of the water from the web during passage thereof through the extended nip is facilitated.
The press felt in a specific embodiment of the present invention includes a base fabric and a permeability control layer which is disposed contiguously on one side of the base fabric.
Additionally, a layer of batt fibers is disposed contiguously relative to the permeability control layer such that the permeability control layer is disposed between the layer of batt fibers and the base fabric for inhibiting rewetting of the web downstream relative to the extended nip and for predictably assisting the web to follow the press felt rather than the pick-up felt downstream relative to the extended nip.
In a preferred embodiment of the present invention as shown in Fig.
12, the press section is inverted such that the pick-up felt is disposed between the shoe and the web.
WO 98/54404 _ PCT/US98/06993 Furthermore, the press felt extends through the extended nip with the press felt being disposed between the backing roll and the web so that the web is disposed between the pick-up felt and the press felt.
The backing roll can be either a plane roll or a vented roll and the bearing blanket can be a plane blanket or a grooved blanket or alternatively a blanket with blind drilled drainage holes defined therein.
Many modifications and variations of the present invention will be readily apparent to those skilled in the art by a consideration of the detailed description contained hereinafter, taken in conjunction with the annexed drawings. However, such modifications and variations fall within the spirit and scope of the present invention as defined by the appended claims.
Figure 1 is a side-elevational view of an extended nip press section apparatus according to the present invention for pressing water from a formed web;
Figure 2 is an enlarged view of the extended nip showing the press shoe as a hydrodynamic shoe;
Figure 3 is a similar view to that shown in Figure 2, but shows an alternative embodiment of the present invention in which the press shoe is a hydrostatic shoe;
Figure 4 is a perspective view of the vented backing roll showing the surface thereof defining a plurality of blind drilled holes;
Figure 5 is a similar view to that shown in Figure 4, but shows an alternative embodiment of the present invention in which the surface of the backing roll defines a plurality of circumferential grooves;
WO 98/54404 _ PCT/US98/Ob993 Figure 6 is a top plan view of a portion of the bearing blanket shown in Figure 1 showing a plain surface thereon;
Figure 7 is a similar view to that shown in Figure 6, but shows the surface of the bearing blanket towards the press felt defining a plurality of grooves for assisting drainage of water from the extended nip;
Figure 8 is an enlarged sectional view of the press felt showing the base fabric, control layer and the layer of batt fibers;
Figure 9 is a graph showing a pressure profile obtained using the apparatus according to the present invention;
Figure 10 is a graph showing another pressure profile achieved using the apparatus according to the present invention;
Figure 11 is a graph showing yet ~ another pressure profile obtained using the apparatus according to the present invention.
Figure 12 is a side elevational view of a preferred embodiment of the present invention; and Figure 13 is a side elevational view of an alternative embodiment of the arrangement shown in Figure 12.
Similar reference characters refer to similar parts throughout the various embodiments of the present invention.
Figure 1 is a side-elevational view of an extended nip press section apparatus, generally designated 10 according to the present invention, for pressing water, as indicated by the arrow 12, from a formed web W. The press section apparatus 10 includes an elongate press shoe 14 and a vented backing roll 16 which cooperates with the shoe 14 for defining therebetween an extended nip 18 for the passage therethrough of the web W.
WO 98154404 _ PCT/US98/06993 A bearing blanket 20 slidably cooperates with the shoe 14 and extends through the extended nip 18. The blanket 20 is disposed between the web W and the shoe 14.
A pick-up felt 22 extends through the extended nip 18 for conveying the web W to and through the extended nip 18. The pick-up felt 22 is disposed between the backing roll 16 and the web W such that the web W
is conveyed between the pick-up felt 22 and the blanket 20 during movement thereof through the extended nip 18.
A press felt 24 extends through the extended nip 18 and is disposed between the blanket 20 and the web W such that the web W is disposed between the press felt 24 and the pick-up felt 22 during movement of the web W through the extended nip 18. The press felt 24 has a water permeability which is less than the water permeability of the pick-up felt 22. The arrangement is such that the web W predictably follows the press felt 24 rather than the pick-up felt 22 when the pick-up felt 22 diverges relative to the press felt 24 downstream relative to the extended nip 18.
The arrangement is such that two-sidedness of the resultant pressed web W is inhibited.
Figure 2 is an enlarged side-elevational view of the elongate press shoe 14 showing the press shoe 14 as a hydrodynamic shoe.
Figure 3 is a similar view to that shown in Figure 2, but shows the press shoe 14A as a hydrostatic shoe.
As shown in Figure 1, the press shoe 14 is disposed beneath the vented backing roll 16.
WO 98/54404 _ PCT/US98/06993 Figure 4 is a perspective view of the vented backing roll 16 shown in Figure 1. As shown in Figure 4, the backing roll 18 has a cylindrical circumferential surface 26 which defines a plurality of blind drilled holes 28, 29 and 30.
Figure 5 is a similar view to that shown in Figure 4, but shows the vented backing roll 16B as having a cylindrical circumferential surface 26B
which defines a plurality of circumferential grooves 28B, 29B and 30B.
In the preferred embodiment of the present invention as shown in Figure 7 , the apparatus 10 includes a saveall 32 which cooperates with the vented backing roll 16 for collecting water 12 removed from the web W
during movement of the web W through the extended nip 18.
Figure 6 is an enlarged top plan view of the bearing blanket 20 showing the surface thereof as being a plain surface.
Figure 7 is a similar view to that shown in Figure 6, but shows an alternative embodiment of the present invention in which the bearing blanket 20C defines a plurality of grooves 34,35 and 36 on a surface thereof facing towards the press felt 24 for assisting drainage from the extended nip 18.
As shown in Figure 1, the apparatus 10 also includes a steam box 38 which is disposed on one side 40 of the pick-up felt 22 for applying steam to the web W supported beneath the pick-up felt 22 upstream relative to the press felt 24.
A vacuum box 42 is disposed on an opposite side 44 of the web W
and pick-up felt 22 relative to the steam box 38. The vacuum box 42 is WO 98/54404 _ PCT/ITS98/06993 connected to a source of partial vacuum 46 such that steam from the steam box 38 is drawn into the web W. The arrangement is such that the viscosity of water within the web W is decreased by the application thereto of the steam so that the subsequent removal of the water from the web W
during passage thereof through the extended nip 18 is facilitated.
Figure 8 is an enlarged sectional view of the press felt 24 which includes a base fabric 48 and a permeability control layer 50 disposed contiguously on one side 52 of the base fabric 48.
A layer of batt fibers 54 are disposed contiguously relative to the permeability control layer 50 such that the permeability control layer 50 is disposed between the layer of batt fibers 54 and the base fabric 48 for inhibiting rewetting of the web W downstream relative to the extended nip 18 and for predictably assisting the web W to follow the press felt 24 rather than the pick-up felt 22 downstream relative to the extended nip 18.
Figures 9, 10 and 11 are graphs showing various pressure profiles 56,58 and 60, respectively, obtained using the equipment according to the present invention.
In operation of the apparatus 10 shown in Figure 1, the web is transferred to the pick-up felt 22 such that the web is disposed beneath the pick-up felt 22.
Steam is applied through the web and is drawn into the web by the vacuum box 42.
The web sandwiched between the pick-up felt 22 and the press felt 24 is guided towards the extended nip 18 where water is removed WO 98154404 _ PCT/US98/06993 therefrom into the saveall 32, which cooperates with the vented backing roll 16 for collecting water 12 removed from the web.
Because of the permeability control layer 50 within the press felt 24, the web predictably follows the press felt 24 rather than the pick-up felt 22. Thereafter, the web is transferred from the press felt 24 into the downstream dryer section, generally designated 62.
In a preferred embodiment of the present invention as shown in Fig.
12, the press section is inverted such that the pick-up felt 22d is disposed between the shoe 14d and the web Wd.
Furthermore, the press felt 24d extends through the extended nip 18d with the press felt 24d being disposed between the backing roll 16d and the web Wd so that the web is disposed between the pick-up felt 22d and the press felt 24d.
The backing roll 16d can be either a plane roll as shown in Fig. 12 or a vented roll 16e as shown in Fig. 13. Also, the bearing blanket 20d can be a plane blanket or a grooved blanket or alternatively a blanket with blind drilled drainage holes defined therein.
The present invention provides a double felted extended nip press, which is particularly capable of pressing a news or fine paper sheet as dry as any of the traditional multi-nip press sections.
Claims (18)
1. An extended nip press section apparatus for pressing water from a formed web, said press section apparatus comprising:
an elongate press shoe;
a vented backing roll cooperating with said shoe for defining therebetween an extended nip for the passage therethrough of the web;
a bearing blanket slidingly cooperating with said shoe and extending through said extended nip, said blanket being disposed between the web and said shoe;
a pick-up felt extending through said extended nip for conveying the web to and through said extended nip; and a press felt extending through said extended nip such that the web is disposed between said press felt and said pick-up felt during movement of the web through said extended nip, said press felt having a water permeability which is less than the water permeability of said pick-up felt such that the web predictably follows said press felt rather than said pick-up felt when said pick-up felt diverges relative to said press felt downstream relative to said extended nip, the arrangement being such that two-sidedness of the resultant pressed web is inhibited.
an elongate press shoe;
a vented backing roll cooperating with said shoe for defining therebetween an extended nip for the passage therethrough of the web;
a bearing blanket slidingly cooperating with said shoe and extending through said extended nip, said blanket being disposed between the web and said shoe;
a pick-up felt extending through said extended nip for conveying the web to and through said extended nip; and a press felt extending through said extended nip such that the web is disposed between said press felt and said pick-up felt during movement of the web through said extended nip, said press felt having a water permeability which is less than the water permeability of said pick-up felt such that the web predictably follows said press felt rather than said pick-up felt when said pick-up felt diverges relative to said press felt downstream relative to said extended nip, the arrangement being such that two-sidedness of the resultant pressed web is inhibited.
2. An extended nip press section apparatus as set forth in claim 1, wherein said elongate press shoe is a hydrodynamic shoe.
3. An extended nip press section apparatus as set forth in claim 1, wherein said elongate press shoe is a hydrostatic shoe.
4. An extended nip press section apparatus as set forth in claim 1, wherein said elongate press shoe is disposed beneath said vented backing roll.
5. An extended nip press section apparatus as set forth in claim 1, wherein said vented backing roll has a cylindrical circumferential surface which defines a plurality of blind drilled holes.
6. An extended nip press section apparatus as set forth in claim 1, wherein said vented backing roll has a cylindrical circumferential surface which defines a plurality of circumferential grooves.
7. An extended nip press section apparatus as set forth in claim 1, further including:
a saveall which cooperates with said vented backing roll for collecting water removed from the web during movement of the web through said extended nip.
a saveall which cooperates with said vented backing roll for collecting water removed from the web during movement of the web through said extended nip.
8. An extended nip press section apparatus as set forth in claim 1, wherein said bearing blanket defines a plurality of grooves on a surface thereof facing towards said press felt for assisting drainage from said extended nip.
9. An extended nip press section apparatus as set forth in claim 1, further including:
a steam box disposed on one side of said pick-up felt for applying steam to the web supported beneath said pick-up felt upstream relative to said press felt;
a vacuum box disposed on an opposite side of the web and pick-up felt relative to said steam box, said vacuum box being connected to source of partial vacuum such that steam from said steam box is drawn into the web, the arrangement being such that the viscosity of water within the web is decreased by the application thereto of the steam so that the subsequent removal of the water from the web during passage thereof through said extended nip is facilitated.
a steam box disposed on one side of said pick-up felt for applying steam to the web supported beneath said pick-up felt upstream relative to said press felt;
a vacuum box disposed on an opposite side of the web and pick-up felt relative to said steam box, said vacuum box being connected to source of partial vacuum such that steam from said steam box is drawn into the web, the arrangement being such that the viscosity of water within the web is decreased by the application thereto of the steam so that the subsequent removal of the water from the web during passage thereof through said extended nip is facilitated.
10. An extended nip press section apparatus as set forth in claim 1, wherein said press felt includes:
a base fabric;
a permeability control layer, disposed contiguously on one side of said base fabric;
a layer of batt fibers disposed contiguously relative to said permeability control layer such that said permeability control layer is disposed between said layer of batt fibers and said base fabric for inhibiting rewetting of the web downstream relative to said extended nip and for predictably assisting the web to follow said press felt rather than said pick-up felt downstream relative to said extended nip.
a base fabric;
a permeability control layer, disposed contiguously on one side of said base fabric;
a layer of batt fibers disposed contiguously relative to said permeability control layer such that said permeability control layer is disposed between said layer of batt fibers and said base fabric for inhibiting rewetting of the web downstream relative to said extended nip and for predictably assisting the web to follow said press felt rather than said pick-up felt downstream relative to said extended nip.
11. An extended nip press section apparatus for pressing water from a formed web, said press section apparatus comprising:
an elongate press shoe;
a vented backing roll disposed above said press shoe and cooperating with said shoe for defining therebetween an extended nip for the passage therethrough of the web;
a bearing blanket slidingly cooperating with said shoe and extending through said extended nip, said blanket being disposed between the web and said shoe;
a pick-up felt extending through said extended nip for conveying the web to and through said extended nip, said pick-up felt being disposed between said backing roll and the web such that the web is conveyed between said pick-up felt and said blanket during movement thereof through said extended nip; and a press felt extending through said extended nip and disposed between said blanket and the web such that the web is disposed between said press felt and said pick-up felt during movement of the web through said extended nip, said press felt having a water permeability which is less than the water permeability of said pick-up felt such that the web predictably follows said press felt rather than said pick-up felt when said pick-up felt diverges relative to said press felt downstream relative to said extended nip, the arrangement being such that two-sidedness of the resultant pressed web is inhibited.
an elongate press shoe;
a vented backing roll disposed above said press shoe and cooperating with said shoe for defining therebetween an extended nip for the passage therethrough of the web;
a bearing blanket slidingly cooperating with said shoe and extending through said extended nip, said blanket being disposed between the web and said shoe;
a pick-up felt extending through said extended nip for conveying the web to and through said extended nip, said pick-up felt being disposed between said backing roll and the web such that the web is conveyed between said pick-up felt and said blanket during movement thereof through said extended nip; and a press felt extending through said extended nip and disposed between said blanket and the web such that the web is disposed between said press felt and said pick-up felt during movement of the web through said extended nip, said press felt having a water permeability which is less than the water permeability of said pick-up felt such that the web predictably follows said press felt rather than said pick-up felt when said pick-up felt diverges relative to said press felt downstream relative to said extended nip, the arrangement being such that two-sidedness of the resultant pressed web is inhibited.
12. An extended nip press section apparatus for pressing water from a formed web, said press section apparatus comprising:
an elongate press shoe;
a vented backing roll cooperating with said shoe for defining therebetween an extended nip for the passage therethrough of the web;
a bearing blanket slidingly cooperating with said shoe and extending through said extended nip, said blanket being disposed between the web and said shoe;
a pick-up felt extending through said extended nip for conveying the web to and through said extended nip, said pick-up felt being disposed between said backing roll and the web such that the web is conveyed between said pick-up felt and said blanket during movement thereof through said extended nip;
a press felt extending through said extended nip and disposed between said blanket and the web such that the web is disposed between said press felt and said pick-up felt during movement of the web through said extended nip, said press felt having a water permeability which is less than the water permeability of said pick-up felt such that the web predictably follows said press felt rather than said pick-up felt when said pick-up felt diverges relative to said press felt downstream relative to said extended nip, the arrangement being such that two-sidedness of the resultant pressed web is inhibited; and a saveall which cooperates with said vented backing roll for collecting water removed from the web and from said backing roll during movement of the web through said extended nip.
an elongate press shoe;
a vented backing roll cooperating with said shoe for defining therebetween an extended nip for the passage therethrough of the web;
a bearing blanket slidingly cooperating with said shoe and extending through said extended nip, said blanket being disposed between the web and said shoe;
a pick-up felt extending through said extended nip for conveying the web to and through said extended nip, said pick-up felt being disposed between said backing roll and the web such that the web is conveyed between said pick-up felt and said blanket during movement thereof through said extended nip;
a press felt extending through said extended nip and disposed between said blanket and the web such that the web is disposed between said press felt and said pick-up felt during movement of the web through said extended nip, said press felt having a water permeability which is less than the water permeability of said pick-up felt such that the web predictably follows said press felt rather than said pick-up felt when said pick-up felt diverges relative to said press felt downstream relative to said extended nip, the arrangement being such that two-sidedness of the resultant pressed web is inhibited; and a saveall which cooperates with said vented backing roll for collecting water removed from the web and from said backing roll during movement of the web through said extended nip.
13. An extended nip press section apparatus for pressing water from the formed web, said press section apparatus comprising:
an elongate press shoe;
a backing roll cooperating with said shoe for defining therebetween an extended nip for the passage therethrough of the web;
a bearing blanket slidingly cooperating with said shoe and extending through said extended nip, said blanket being disposed between the web and said shoe;
a pick-up felt extending through said extended nip for conveying the web to and through said extended nip, said pick-up felt being disposed between said blanket and the web such that the web is conveyed between said pick-up felt and said backing roll during movement thereof through said extended nip; and a press felt extending through said extended nip and disposed between said backing roll and the web such that the web is disposed between said press felt and said pick-up felt during movement of the web through said extended nip, said press felt having a water permeability which is less than the water permeability of said pick-up felt such that the web predictably follows said press felt rather than said pick-up felt when said pick-up felt diverges relative to said press felt downstream relative to said extended nip, the arrangement being such that two-sidedness of the resultant pressed web is inhibited.
an elongate press shoe;
a backing roll cooperating with said shoe for defining therebetween an extended nip for the passage therethrough of the web;
a bearing blanket slidingly cooperating with said shoe and extending through said extended nip, said blanket being disposed between the web and said shoe;
a pick-up felt extending through said extended nip for conveying the web to and through said extended nip, said pick-up felt being disposed between said blanket and the web such that the web is conveyed between said pick-up felt and said backing roll during movement thereof through said extended nip; and a press felt extending through said extended nip and disposed between said backing roll and the web such that the web is disposed between said press felt and said pick-up felt during movement of the web through said extended nip, said press felt having a water permeability which is less than the water permeability of said pick-up felt such that the web predictably follows said press felt rather than said pick-up felt when said pick-up felt diverges relative to said press felt downstream relative to said extended nip, the arrangement being such that two-sidedness of the resultant pressed web is inhibited.
14. An extended nip press section apparatus as set forth in claim 13 wherein said backing roll is a plane roll.
15. An extended nip press section apparatus as set forth in claim 13 wherein said backing roll is a vented roll.
16. An extended nip press section apparatus as set forth in claim 13 wherein said bearing blanket is a plane blanket.
17. An extended nip press section apparatus as set forth in claim 13 wherein said bearing blanket defines a plurality of drainage grooves.
18. An extended nip press section apparatus as set forth in claim 13 wherein said bearing blanket defines a plurality of blind drilled drainage holes.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US86470797A | 1997-05-28 | 1997-05-28 | |
| US08/864,707 | 1997-05-28 | ||
| PCT/US1998/006993 WO1998054404A1 (en) | 1997-05-28 | 1998-04-06 | An extended nip press section apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2325914A1 true CA2325914A1 (en) | 1998-12-03 |
Family
ID=25343879
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002325914A Abandoned CA2325914A1 (en) | 1997-05-28 | 1998-04-06 | An extended nip press section apparatus |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU6957598A (en) |
| CA (1) | CA2325914A1 (en) |
| WO (1) | WO1998054404A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI120747B (en) * | 2006-09-21 | 2010-02-15 | Metso Paper Inc | Paper or cardboard machine |
| DE102010029580A1 (en) * | 2010-06-01 | 2011-12-01 | Voith Patent Gmbh | Machine for producing a paper web, in particular a sack paper web |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4483745A (en) * | 1982-09-29 | 1984-11-20 | Beloit Corporation | Method and apparatus of sheet transfer using a nonporous smooth surfaced belt |
| FI82500C (en) * | 1985-02-18 | 1991-03-11 | Valmet Oy | Press section with separate press nip in a paper machine |
| FI95610C (en) * | 1994-10-06 | 1996-02-26 | Valmet Paper Machinery Inc | Press section of a paper machine equipped with a compensating press |
| FI114227B (en) * | 1995-04-24 | 2004-09-15 | Metso Paper Inc | Paper machine with press section and dryer section |
| FI98843C (en) * | 1995-10-03 | 1997-08-25 | Valmet Corp | A method and apparatus for removing water from a paper or board web by compression |
-
1998
- 1998-04-06 CA CA002325914A patent/CA2325914A1/en not_active Abandoned
- 1998-04-06 WO PCT/US1998/006993 patent/WO1998054404A1/en active Application Filing
- 1998-04-06 AU AU69575/98A patent/AU6957598A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| AU6957598A (en) | 1998-12-30 |
| WO1998054404A1 (en) | 1998-12-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |