CA2190563C - Device and method to stabilize sheet between press section and dryer section of a paper-making machine - Google Patents
Device and method to stabilize sheet between press section and dryer section of a paper-making machineInfo
- Publication number
- CA2190563C CA2190563C CA002190563A CA2190563A CA2190563C CA 2190563 C CA2190563 C CA 2190563C CA 002190563 A CA002190563 A CA 002190563A CA 2190563 A CA2190563 A CA 2190563A CA 2190563 C CA2190563 C CA 2190563C
- Authority
- CA
- Canada
- Prior art keywords
- venturi
- felt
- air
- fabric
- jet
- 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 - Fee Related
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Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
- D21G9/00—Other accessories for paper-making machines
- D21G9/0063—Devices for threading a web tail through a paper-making machine
Abstract
A novel sheet transfer stabilizer is provided for transferring a fibrous wet sheet from a press section to a dryer section of a paper-making machine by way of a felt or fabric. The sheet transfer stabilizer includes a composite Venturi box which is disposed between a felt or fabric roll of the press section and a first dryer. The Venturi box includes three side-by-side Venturis, namely an inlet Venturi, an outlet Venturi, and a main Venturi. Such Venturi boxes are used to create and maintain a vacuum in the felt or fabric web system. In addition, a novel method is provided for guiding a wet fibrous web from a press section to a drying section of a paper-making machine. The method includes the steps of passing the wet fibrous web from the press section in an open draw onto a felt or fabric, the felt or fabric passing about a guide roll. The wet fibrous web and the felt or fabric, are urged against each other as a drying wire of the drying section passes from the guide roll to a drying cylinder by the generation of negative pressure in the space on the side of the felt or fabric, which is opposite to the side of the felt or fabric, which supports the fibrous web. The negative pressure is generated using the combination of an inlet Venturi, having an inlet opening and a throat, the inlet Venturi being located adjacent to the guide roll in order to draw up and exhaust air from an area where the paper web separates from the surface of the guide roll, or an outlet Venturi having an inlet opening and a throat, the outlet Venturi being situated adjacent to the drying cylinder to draw away air from a gap between the dryer cylinder and the inlet opening of the outlet Venturi; or a main Venturi having a first and second inlet openings and throat, the main Venturi being disposed between the inlet Venturi and the outlet Venturi to draw away air away from, and to maintain a negative static pressure over, an unsupported span between the guide roll and the dryer cylinder.
Description
(a) TITLE OF THE INVENTION
Device and Method To Stabilize Sheet Between Press Section and Dryer Section of a Paper-Making Machine (b) TECHNICAL FIELD TO WHICH THE INVENTION RELATES
This invention relates both to a device and to a method to stabilize a sheet between the press section and the dryer section of a paper-making machine.
More particularly, the present invention is directed to such a device and method for guiding a fibrous web from a press section to a drying section of a paper-making machine, in which the paper web is guided and supported on a drying felt or fabric wire as the paper web is guided into the drying section, e. g. , around an initial group of drying cylinders.
(c) BACKGROUND ART
After pressing, a fibrous web, e.g., a paper web which is prepared in a paper-making machine, is extremely weak. A large number of breaks in the paper web tend to occur in the run thereof between the press section and a first drying cylinder within a drying section of the paper-making machine.
The prior art is familiar with a press section which comprises a closed roll combination having four press rolls, in which the first nip was formed between a hollow-faced roll and a suction roll, and was provided with two pressing felts or fabrics. The second single-felt or single-fabric nip of the press section was formed between the suction roll and a centre roll of the press section. The centre roll of the press section was a smooth-faced stone roll, the third, final, nip of the press section being formed in connection with this stone roll and being provided with its own felt or fabric. The running fibrous web was detached from the smooth face of the stone roll in the press section by extending or stretching the paper web in the running direction.
In recent years the running speeds of paper-making machines have been increasing constantly up to 1500 meters per minute. At such speeds, fluttering of the paper web becomes a serious problem deteriorating the running quality. When the running speed of a paper-making machine becomes higher than 1000 m/min. , the air flows produced by the wires greatly affect the running quality. Unless these air flows are controlled, the result is fluttering of the paper web, wrinkles, uneven drying, and even web breaks, with costly standstills resulting from them. It has been found that the passing of the paper web from the press section into the drying section and the supporting of the paper web cannot be effectively controlled by means of the methods and devices which were suggested in the prior art.
It is presently the opinion in this industry that paper web flutter is mainly the result of strong air current flows within the pockets defined within the drying section, and by pressure differentials in the pockets as well as in the nips formed by the paper web, drying wire and cylinder surfaces. The strong air flows and pressure differentials are the consequence of boundary layer flows induced by the moving wire, paper web and cylinder surfaces.
The pockets mentioned above are formed by the free paper web draws, free cylinder surfaces, and wires or felts or fabrics which are guided by guide rolls. These pockets are closed except at their transverse ends and the ventilation of the pockets is considered to be an important factor from the viewpoint of efficiency and uniformity of the moisture profile obtained.
A typical prior art arrangement between the press section and the dryer section includes the following components: a felt or fabric roll; a first dryer; a felt or fabric that supports the paper sheet; and the paper sheet itself. The problem in this arrangement is that the paper sheet separates from the felt or fabric as it travels over a relatively long span between the press section and the dryer section. Since it separates, it becomes prone to wrinkles and possibly to tearing, thus causing paper sheet breaks.
The main cause of the problem is due to machine speed. As machine speeds increase, the amount of air entrained by a felt or fabric increases greatly. The area formed by the felt or fabric as it comes around the felt or fabric roll is a pocket into which air is pumped, with the only escape being back through the felt or fabric. As the air forces through the felt or fabric in all directions, it also forces the paper sheet away from the felt fabric. The paper sheet can form bubbles, it can flutter and form wrinkles and break.
Some solutions proposed to alleviate this problem use high velocity jets of air to entrain surrounding air and thus to evacuate this pocket. Any high velocity air jet has negative pressure in its wake which will cause surrounding air to be entrained with the jet. Therefore, if properly directed, this arrangement can expel air from a given area.
In such typical layout, a box with high velocity jets, properly placed will evacuate much of the air being pushed through the felt or fabric and onto the paper.
Although these systems work, such solution is qualitative in nature since the relationship between the nozzle flow and velocity and the amount of entrained air cannot be firmly established.
Some recently suggested solutions to these problems have allegedly been provided by the following patents:
U.S. Patent No. 4,551,203 patented November 5, 1987 by P. Eskelinen [and its corresponding Canadian Patent No. 1,243,197 issued October 13, 1988 provided a method and arrangement for guiding a paper web from the press section to the drying section. The apparatus included a guide roll which was adapted to guide the paper web passing from the press section onto a drying wire from the drying section passing about the guide roll. Means were provided for urging the paper web and drying wire against one another as the paper web was passed to the drying section. The urging means was disposed between the guide roll and the drying section in a running direction of the web and wire. The guide roll constituted the means for passing the paper web in an open draw from the press section onto the drying wire. The urging means included means for generating a negative pressure in a space which was adjacent to a side of the drying wire opposite a side which contacted the paper web, to urge the paper web and drying wire against each other. The negative pressure generating means comprised at least one blowing box having gas discharge means extending substantially over an entire width of the paper web. The blowing box directed a gas stream through the gas discharge means in a direction which was substantially parallel to the running direction of the web and supporting drying wire. The discharge speed of the gas was greater than a running speed of the drying wire. This created negative pressure between the blowing box and the drying wire in order to urge the paper web and drying wire against one another.
The method of this patent included the step of passing the paper web from the press section in an open draw onto a drying wire passing about a guide roll.
The next step involved urging the paper web and drying wire against each other as the drying wire passed from the guide roll to the drying section. This urging was accomplished by ejecting gas out of blowing means on a side of the drying wire opposite to a side supporting the paper web in a direction which was substantially parallel to a running direction of the drying wire and paper web and at a speed greater than a running speed of the drying wire in order to generate negative pressure in a space between the blowing means and the drying wire.
U.S. Patent No. 4,694,587 patented September 22, 1987 by P. Eskelinen [and its corresponding Canadian Patent No. 1,336,107 issued August 8, 1995 provided an apparatus used in a twin-wire cylinder drying section of a paper-making machine. The twin-wire drying section of a paper-making machine included upper and lower rows of drying cylinders with an upper drying wire guided by the upper drying cylinders and upper guide rolls situated between the upper drying cylinders and with a lower drying wire guided by the lower drying cylinders, and lower guide rolls situated between the lower drying cylinders. A paper web was pressed by the upper wire in direct drying contact with the surfaces of the upper drying cylinders and was pressed by the upper wire in direct drying contact with the surfaces of the lower drying cylinders and had a free draw of a certain length between a drying cylinder of one row and a drying cylinder of another row. A vacuum zone was arranged on a run of a drying wire between a drying cylinder and the next guide roll which caused the paper web to be suctioned against the drying wire so that the length of the free run of the paper web was substantially shortened. The suction was created by directing air jets in directions opposite to the running directions of the drying wire run and the guide roll which ejected air from spaces behind them thereby creating the vacuum zone.
(d) DESCRIPTION OF THE INVENTION
The above purported solutions did not effectively or completely solve the problem outlined. Accordingly, it is an object of one aspect of the present invention to provide a new and improved apparatus and method for guiding a fibrous web, e. g. , a paper web, from a press section to a drying section, in which such paper web can be smoothly and securely guided in the run from the press section to the drying section.
It is an object of another aspect of the present invention to provide an improved method and apparatus for guiding a fibrous paper web from a press section to a drying section, which substantially eliminates any detrimental fluttering of the paper web as it passes from the press section to the drying section.
It is an object of a further aspect of the present invention to provide an improved apparatus and method for guiding a fibrous paper web from a press section to a drying S section, in which such paper web is suitably guided on a suitable running support.
An object of a further aspect of the present invention is to exhaust air from the pocket which is formed by the felt or fabric and the felt or fabric roll.
An object of yet a further aspect of the present invention is to exhaust any air which is carried by the felt or fabric between the felt or fabric roll and the first dryer.
An object of a still further aspect of the present invention is to create a suction (negative pressure) above the felt or fabric, in the span between the felt or fabric roll and the first dryer.
By a first broad aspect of this invention, a sheet transfer stabilizer is provided for transferring a wet fibrous paper sheet from a press section to a dryer section of a paper-making machine by way of a felt or fabric, the sheet transfer stabilizer comprising i) a Venturi box for stabilizing the wet fibrous paper sheet which is being transferred from the press section to the dryer section of the paper-making machine by way of the felt or fabric, by the generation of negative pressure in the space on the side of the felt or fabric which is opposite to the side of the felt or fabric which supports the paper web, the Venturi box being disposed between a guide roller of the press section and a first dryer, the Venturi box including three side-by-side Venturis, comprising an inlet Venturi, the inlet being defined by a pair of spaced-apart, substantially-parallel, forward surfaces, the spaced-apart, substantially-parallel, forward surfaces being angularly-disposed to the plane of the felt or fabric, and including means for generated a flow of at least one jet of air into a space between the spaced-apart, substantially-parallel, forward surfaces, the flow of the at least one jet of air thereby generated a negative pressure at the inlet Venturi, the at least one jet of air then being discharged in an angular direction away from the felt or fabric; ii) an outlet Venturi, the outlet Venturi being defined by a pair of spaced-apart, substantially-parallel, rear surfaces, the spaced-apart, substantially-parallel, rear surfaces being angularly-disposed to the plane of the felt or fabric, and including means for generating or flow of at least one jet of air into a space between the spaced-apart, substantially-parallel, rear surfaces, the flow of at least one jet of air thereby generating a negative pressure at the outlet Venturi, the at least one jet of air then being discharged in an angular direction away from the felt or fabric;
and iii) a main Venturi, the main Venturi being defined by a pair of central, spaced-apart, substantially-parallel surfaces, the central spaced-apart, substantially-parallel surfaces being disposed, either angularly or perpendicularly, to the plane of the felt or fabric, and including means for generating the flow of at least one jet of air into a space between the spaced-apart, substantially-parallel surfaces, the flow of the at least one jet of air thereby generating a negative pressure at the main Venturi, the at least one jet of air then being discharged in a perpendicular, or in an angular, direction away from the felt or fabric.
By a first variant of this first aspect of the invention, the sheet transfer stabilizer includes a respective damper in an opening in a respective interior wall within the interior of the sheet transfer stabilizer leading to the respective Venturi, each the respective damper being selectively-movable from a fully-open to a fully-closed position thereby to control at least one of: i) the amount of primary air in the at least one jet of air which is discharged into the inlet Venturi; ii) the amount of primary air in the at least one jet of air which is discharged into the outlet Venturi; iii) the amount of primary air in a first jet of air which is discharged into the main Venturi; and iv) the amount of primary air in a second jet of air which is discharged into the main Venturi.
By a second variant of this first aspect of the invention, and/or the above variant thereof, the sheet transfer stabilizer includes a recessed central portion between an inlet end and an outlet end of the sheet transfer stabilizer to help to create a plenum effect in order to enhance the effect of negative static pressure which may be generated.
By a third variant of this first aspect of this invention, and/or the above variants thereof, the distance between the paper web and the inlet opening of the inlet Venturi, and the distance between the paper web and the inlet opening of the outlet Venturi is from 1/4 inch to 3/4 inch.
By a second broad aspect of this invention, a method is provided for guiding a wet fibrous web from a press section to a drying section of a paper-making machine, comprising the steps of passing the wet fibrous web from the press section in an open draw onto a felt or fabric, the felt or fabric passing about a guide roll, and urging the wet fibrous web and the felt or fabric, against each other as a drying wire of the drying section passes from the guide roll to a drying cylinder by the generation of negative pressure in the space on the side of the felt or fabric, which is opposite to the side of the felt or fabric, which supports the fibrous web, wherein the negative pressure is generated using the combination of i) an inlet Venturi, having an inlet opening and a throat, the inlet Venturi being located adjacent to the guide roll in order to draw up and exhaust air from an area where the web separates from the surface of the guide roll, ii) an outlet Venturi having an inlet opening and a throat, the outlet Venturi being situated adjacent to the drying cylinder to draw away air from a gap between the dryer cylinder and the inlet opening of the outlet Venturi; and iii) a main Venturi having a first inlet opeing and a second inlet opening and throat, the main Venturi being disposed between the inlet Venturi and the outlet Venturi to draw away air away from, and to maintain a negative static pressure over, an unsupported span between the guide roll and the dryer cylinder.
By a first variant of this second aspect of the invention, negative pressures at the Venturis are generated at each of the inlet Venturi, the outlet Venturi and the main Venturi, by at least one of: a) at the inlet Venturi, by expelling a jet of air at a high velocity into the throat of the inlet Venturi and then by discharging the jet of air angularly away from the plane of the felt or fabric; b) at the outlet Venturi, by expelling a jet of air at a high velocity into the throat of the outlet Venturi and by discharging the jet of air angularly away from the plane of the felt or fabric; and c) at the main Venturi by expelling a first jet of air at a high velocity into the throat of the main Venturi and by discharging the first jet of air perpendicularly to the plane of the felt or fabric, or by discharging the first jet of air angularly away from the plane of the felt or fabric.
By a second variant of this second aspect of the invention, and/or the above variant thereof, the primary air flow is at least one of the following: a) of from 50 to 200 CPM/ft; from the inlet opening of the outlet Venturi into the throat of the outlet Venturi; b) of from 50 to 200 CFM/ft from the inlet opening of the inlet Venturi into g the throat of the inlet Venturi; and c) of from 50 to 400 CFM/ft from the first inlet opening of the main Venturi into the throat of the main Venturi.
By a third variant of this second aspect of the invention, and/or the above variants thereof, the steps as disclosed above, negative pressure at the main Venturi is generated by additionally-expelling a second jet of air at a high velocity into the throat of the main Venturi and by discharging the second jet of air perpendicularly to the plane of the felt or fabric, or by discharging the second jet of air angularly away from the plane of the felt or fabric.
By a fourth variant of this second aspect of the invention, and/or the above variants thereof, the distance between the web and the inlet opening of the inlet Venturi, and the distance between the web and the inlet opening of the outlet Venturi is from 1 /4 inch to 3/4 inch.
(e) DESCRIPTION OF THE FIGURES
In the accompanying drawings, Fig. 1 is a schematic view of the area of a paper-making machine of a typical prior art installation between the press section and the drying section;
Fig. 2 is a schematic view of the area of a paper-making machine between the press section and the drying section according to an aspect of one embodiment of the present invention;
Fig. 3 is an enlarged view of the sheet transfer stabilizer according to an aspect of one embodiment of the present invention shown in Fig. 2, and Figs. 4 and 5 are graphs which show the performance of the sheet transfer stabilizer according to an aspect of one embodiment of the present invention.
(fj DESCRIPTION OF THE PRIOR ART
Fig. 1 (the prior art) shows three blow boxes one after the other. The blow boxes each have a planar bottom face which is located at a distance O from the opposite drying wire. The distance O is preferably within the range of 10 to 25 mm. At both ends of the planar bottom wall of the blow boxes, nozzle slots are located, by means of which the blow jets are generated. The downstream nozzle slot of the last nozzle box is located substantially at the position at which the drying wire and the paper web achieve contact with the first drying cylinder. The fetching roll may also be arranged as a suction roll, and the suction zone a of the roll is shown in broken lines.
Additional air jets of the blow boxes are directed opposite to the direction of movement of the wire or paper web and of the roll. According to the prior art, it was alleged that the ejection effect of the jets prevented generation of detrimental positive pressures.
(g) ONE MODE FOR CARRYING OUT THE INVENTION
As seen in Fig. 2, one aspect of one embodiment of the present invention provides a sheet transfer stabilizer 10 which is disposed above the felt or fabric 11 between the felt or fabric roll 12 and the first dryer cylinder 13. The sheet transfer stabilizer is in the shape of a box 14, extending transversely across the entire width of the felt or fabric 11 and the web 15. The sheet transfer stabilizer 10 is provided with an inlet Venturi 16, a main Venturi 17 and an outlet Venturi 18.
The detailed internal structure of the sheet transfer stabilizer 10 of Fig. 2 is shown in Fig. 3. As shown in Fig. 3, the inlet Venturi 16 is formed by the surface 20 and surfaces 21,22 which are parallel thereto. Primary air from one nozzle 23 (or from a series of nozzles) is discharged into the throat 24 which is formed by surfaces 20, and 21, 22 . The suction thus created draws air in through opening 25 , as shown by arrows A. The combined air is discharged through inlet discharge opening 26.
Air which is carried along by the felt or fabric 11 is exhausted through the outlet Venturi 17. The outlet Venturi 17 is formed by the surface 30 and surfaces 31, parallel thereto. Primary air from one nozzle 33 (or from a series of nozzles) is discharged into the throat 34 which is formed by surfaces 30 and 31, 32. The suction thus created draws air in through opening 35, as shown by arrow B. The combined air is discharged through outlet discharge opening 36.
The main function of the sheet transfer stabilizer 10 is to create a negative pressure above the felt or fabric 11 so as to keep the web 15 in close contact with the felt or fabric 11. This is primarily achieved by the main Venturi 18. Air is exhausted from the plenum C, by the main Venturi 18. The main Venturi 18 is formed by the surfaces 40,41 and 42,43. Primary air from a nozzle 44 or 45, (or from a series of such nozzles), or from both nozzles 44,45, (or from all of a series of such nozzles), is discharged into the throat 46 which is formed by surfaces 40,41 and 42,43. The suction thus created draws air in through opening 47, as shown by arrow D. The combined air is discharged through main discharge 48 opening.
Device and Method To Stabilize Sheet Between Press Section and Dryer Section of a Paper-Making Machine (b) TECHNICAL FIELD TO WHICH THE INVENTION RELATES
This invention relates both to a device and to a method to stabilize a sheet between the press section and the dryer section of a paper-making machine.
More particularly, the present invention is directed to such a device and method for guiding a fibrous web from a press section to a drying section of a paper-making machine, in which the paper web is guided and supported on a drying felt or fabric wire as the paper web is guided into the drying section, e. g. , around an initial group of drying cylinders.
(c) BACKGROUND ART
After pressing, a fibrous web, e.g., a paper web which is prepared in a paper-making machine, is extremely weak. A large number of breaks in the paper web tend to occur in the run thereof between the press section and a first drying cylinder within a drying section of the paper-making machine.
The prior art is familiar with a press section which comprises a closed roll combination having four press rolls, in which the first nip was formed between a hollow-faced roll and a suction roll, and was provided with two pressing felts or fabrics. The second single-felt or single-fabric nip of the press section was formed between the suction roll and a centre roll of the press section. The centre roll of the press section was a smooth-faced stone roll, the third, final, nip of the press section being formed in connection with this stone roll and being provided with its own felt or fabric. The running fibrous web was detached from the smooth face of the stone roll in the press section by extending or stretching the paper web in the running direction.
In recent years the running speeds of paper-making machines have been increasing constantly up to 1500 meters per minute. At such speeds, fluttering of the paper web becomes a serious problem deteriorating the running quality. When the running speed of a paper-making machine becomes higher than 1000 m/min. , the air flows produced by the wires greatly affect the running quality. Unless these air flows are controlled, the result is fluttering of the paper web, wrinkles, uneven drying, and even web breaks, with costly standstills resulting from them. It has been found that the passing of the paper web from the press section into the drying section and the supporting of the paper web cannot be effectively controlled by means of the methods and devices which were suggested in the prior art.
It is presently the opinion in this industry that paper web flutter is mainly the result of strong air current flows within the pockets defined within the drying section, and by pressure differentials in the pockets as well as in the nips formed by the paper web, drying wire and cylinder surfaces. The strong air flows and pressure differentials are the consequence of boundary layer flows induced by the moving wire, paper web and cylinder surfaces.
The pockets mentioned above are formed by the free paper web draws, free cylinder surfaces, and wires or felts or fabrics which are guided by guide rolls. These pockets are closed except at their transverse ends and the ventilation of the pockets is considered to be an important factor from the viewpoint of efficiency and uniformity of the moisture profile obtained.
A typical prior art arrangement between the press section and the dryer section includes the following components: a felt or fabric roll; a first dryer; a felt or fabric that supports the paper sheet; and the paper sheet itself. The problem in this arrangement is that the paper sheet separates from the felt or fabric as it travels over a relatively long span between the press section and the dryer section. Since it separates, it becomes prone to wrinkles and possibly to tearing, thus causing paper sheet breaks.
The main cause of the problem is due to machine speed. As machine speeds increase, the amount of air entrained by a felt or fabric increases greatly. The area formed by the felt or fabric as it comes around the felt or fabric roll is a pocket into which air is pumped, with the only escape being back through the felt or fabric. As the air forces through the felt or fabric in all directions, it also forces the paper sheet away from the felt fabric. The paper sheet can form bubbles, it can flutter and form wrinkles and break.
Some solutions proposed to alleviate this problem use high velocity jets of air to entrain surrounding air and thus to evacuate this pocket. Any high velocity air jet has negative pressure in its wake which will cause surrounding air to be entrained with the jet. Therefore, if properly directed, this arrangement can expel air from a given area.
In such typical layout, a box with high velocity jets, properly placed will evacuate much of the air being pushed through the felt or fabric and onto the paper.
Although these systems work, such solution is qualitative in nature since the relationship between the nozzle flow and velocity and the amount of entrained air cannot be firmly established.
Some recently suggested solutions to these problems have allegedly been provided by the following patents:
U.S. Patent No. 4,551,203 patented November 5, 1987 by P. Eskelinen [and its corresponding Canadian Patent No. 1,243,197 issued October 13, 1988 provided a method and arrangement for guiding a paper web from the press section to the drying section. The apparatus included a guide roll which was adapted to guide the paper web passing from the press section onto a drying wire from the drying section passing about the guide roll. Means were provided for urging the paper web and drying wire against one another as the paper web was passed to the drying section. The urging means was disposed between the guide roll and the drying section in a running direction of the web and wire. The guide roll constituted the means for passing the paper web in an open draw from the press section onto the drying wire. The urging means included means for generating a negative pressure in a space which was adjacent to a side of the drying wire opposite a side which contacted the paper web, to urge the paper web and drying wire against each other. The negative pressure generating means comprised at least one blowing box having gas discharge means extending substantially over an entire width of the paper web. The blowing box directed a gas stream through the gas discharge means in a direction which was substantially parallel to the running direction of the web and supporting drying wire. The discharge speed of the gas was greater than a running speed of the drying wire. This created negative pressure between the blowing box and the drying wire in order to urge the paper web and drying wire against one another.
The method of this patent included the step of passing the paper web from the press section in an open draw onto a drying wire passing about a guide roll.
The next step involved urging the paper web and drying wire against each other as the drying wire passed from the guide roll to the drying section. This urging was accomplished by ejecting gas out of blowing means on a side of the drying wire opposite to a side supporting the paper web in a direction which was substantially parallel to a running direction of the drying wire and paper web and at a speed greater than a running speed of the drying wire in order to generate negative pressure in a space between the blowing means and the drying wire.
U.S. Patent No. 4,694,587 patented September 22, 1987 by P. Eskelinen [and its corresponding Canadian Patent No. 1,336,107 issued August 8, 1995 provided an apparatus used in a twin-wire cylinder drying section of a paper-making machine. The twin-wire drying section of a paper-making machine included upper and lower rows of drying cylinders with an upper drying wire guided by the upper drying cylinders and upper guide rolls situated between the upper drying cylinders and with a lower drying wire guided by the lower drying cylinders, and lower guide rolls situated between the lower drying cylinders. A paper web was pressed by the upper wire in direct drying contact with the surfaces of the upper drying cylinders and was pressed by the upper wire in direct drying contact with the surfaces of the lower drying cylinders and had a free draw of a certain length between a drying cylinder of one row and a drying cylinder of another row. A vacuum zone was arranged on a run of a drying wire between a drying cylinder and the next guide roll which caused the paper web to be suctioned against the drying wire so that the length of the free run of the paper web was substantially shortened. The suction was created by directing air jets in directions opposite to the running directions of the drying wire run and the guide roll which ejected air from spaces behind them thereby creating the vacuum zone.
(d) DESCRIPTION OF THE INVENTION
The above purported solutions did not effectively or completely solve the problem outlined. Accordingly, it is an object of one aspect of the present invention to provide a new and improved apparatus and method for guiding a fibrous web, e. g. , a paper web, from a press section to a drying section, in which such paper web can be smoothly and securely guided in the run from the press section to the drying section.
It is an object of another aspect of the present invention to provide an improved method and apparatus for guiding a fibrous paper web from a press section to a drying section, which substantially eliminates any detrimental fluttering of the paper web as it passes from the press section to the drying section.
It is an object of a further aspect of the present invention to provide an improved apparatus and method for guiding a fibrous paper web from a press section to a drying S section, in which such paper web is suitably guided on a suitable running support.
An object of a further aspect of the present invention is to exhaust air from the pocket which is formed by the felt or fabric and the felt or fabric roll.
An object of yet a further aspect of the present invention is to exhaust any air which is carried by the felt or fabric between the felt or fabric roll and the first dryer.
An object of a still further aspect of the present invention is to create a suction (negative pressure) above the felt or fabric, in the span between the felt or fabric roll and the first dryer.
By a first broad aspect of this invention, a sheet transfer stabilizer is provided for transferring a wet fibrous paper sheet from a press section to a dryer section of a paper-making machine by way of a felt or fabric, the sheet transfer stabilizer comprising i) a Venturi box for stabilizing the wet fibrous paper sheet which is being transferred from the press section to the dryer section of the paper-making machine by way of the felt or fabric, by the generation of negative pressure in the space on the side of the felt or fabric which is opposite to the side of the felt or fabric which supports the paper web, the Venturi box being disposed between a guide roller of the press section and a first dryer, the Venturi box including three side-by-side Venturis, comprising an inlet Venturi, the inlet being defined by a pair of spaced-apart, substantially-parallel, forward surfaces, the spaced-apart, substantially-parallel, forward surfaces being angularly-disposed to the plane of the felt or fabric, and including means for generated a flow of at least one jet of air into a space between the spaced-apart, substantially-parallel, forward surfaces, the flow of the at least one jet of air thereby generated a negative pressure at the inlet Venturi, the at least one jet of air then being discharged in an angular direction away from the felt or fabric; ii) an outlet Venturi, the outlet Venturi being defined by a pair of spaced-apart, substantially-parallel, rear surfaces, the spaced-apart, substantially-parallel, rear surfaces being angularly-disposed to the plane of the felt or fabric, and including means for generating or flow of at least one jet of air into a space between the spaced-apart, substantially-parallel, rear surfaces, the flow of at least one jet of air thereby generating a negative pressure at the outlet Venturi, the at least one jet of air then being discharged in an angular direction away from the felt or fabric;
and iii) a main Venturi, the main Venturi being defined by a pair of central, spaced-apart, substantially-parallel surfaces, the central spaced-apart, substantially-parallel surfaces being disposed, either angularly or perpendicularly, to the plane of the felt or fabric, and including means for generating the flow of at least one jet of air into a space between the spaced-apart, substantially-parallel surfaces, the flow of the at least one jet of air thereby generating a negative pressure at the main Venturi, the at least one jet of air then being discharged in a perpendicular, or in an angular, direction away from the felt or fabric.
By a first variant of this first aspect of the invention, the sheet transfer stabilizer includes a respective damper in an opening in a respective interior wall within the interior of the sheet transfer stabilizer leading to the respective Venturi, each the respective damper being selectively-movable from a fully-open to a fully-closed position thereby to control at least one of: i) the amount of primary air in the at least one jet of air which is discharged into the inlet Venturi; ii) the amount of primary air in the at least one jet of air which is discharged into the outlet Venturi; iii) the amount of primary air in a first jet of air which is discharged into the main Venturi; and iv) the amount of primary air in a second jet of air which is discharged into the main Venturi.
By a second variant of this first aspect of the invention, and/or the above variant thereof, the sheet transfer stabilizer includes a recessed central portion between an inlet end and an outlet end of the sheet transfer stabilizer to help to create a plenum effect in order to enhance the effect of negative static pressure which may be generated.
By a third variant of this first aspect of this invention, and/or the above variants thereof, the distance between the paper web and the inlet opening of the inlet Venturi, and the distance between the paper web and the inlet opening of the outlet Venturi is from 1/4 inch to 3/4 inch.
By a second broad aspect of this invention, a method is provided for guiding a wet fibrous web from a press section to a drying section of a paper-making machine, comprising the steps of passing the wet fibrous web from the press section in an open draw onto a felt or fabric, the felt or fabric passing about a guide roll, and urging the wet fibrous web and the felt or fabric, against each other as a drying wire of the drying section passes from the guide roll to a drying cylinder by the generation of negative pressure in the space on the side of the felt or fabric, which is opposite to the side of the felt or fabric, which supports the fibrous web, wherein the negative pressure is generated using the combination of i) an inlet Venturi, having an inlet opening and a throat, the inlet Venturi being located adjacent to the guide roll in order to draw up and exhaust air from an area where the web separates from the surface of the guide roll, ii) an outlet Venturi having an inlet opening and a throat, the outlet Venturi being situated adjacent to the drying cylinder to draw away air from a gap between the dryer cylinder and the inlet opening of the outlet Venturi; and iii) a main Venturi having a first inlet opeing and a second inlet opening and throat, the main Venturi being disposed between the inlet Venturi and the outlet Venturi to draw away air away from, and to maintain a negative static pressure over, an unsupported span between the guide roll and the dryer cylinder.
By a first variant of this second aspect of the invention, negative pressures at the Venturis are generated at each of the inlet Venturi, the outlet Venturi and the main Venturi, by at least one of: a) at the inlet Venturi, by expelling a jet of air at a high velocity into the throat of the inlet Venturi and then by discharging the jet of air angularly away from the plane of the felt or fabric; b) at the outlet Venturi, by expelling a jet of air at a high velocity into the throat of the outlet Venturi and by discharging the jet of air angularly away from the plane of the felt or fabric; and c) at the main Venturi by expelling a first jet of air at a high velocity into the throat of the main Venturi and by discharging the first jet of air perpendicularly to the plane of the felt or fabric, or by discharging the first jet of air angularly away from the plane of the felt or fabric.
By a second variant of this second aspect of the invention, and/or the above variant thereof, the primary air flow is at least one of the following: a) of from 50 to 200 CPM/ft; from the inlet opening of the outlet Venturi into the throat of the outlet Venturi; b) of from 50 to 200 CFM/ft from the inlet opening of the inlet Venturi into g the throat of the inlet Venturi; and c) of from 50 to 400 CFM/ft from the first inlet opening of the main Venturi into the throat of the main Venturi.
By a third variant of this second aspect of the invention, and/or the above variants thereof, the steps as disclosed above, negative pressure at the main Venturi is generated by additionally-expelling a second jet of air at a high velocity into the throat of the main Venturi and by discharging the second jet of air perpendicularly to the plane of the felt or fabric, or by discharging the second jet of air angularly away from the plane of the felt or fabric.
By a fourth variant of this second aspect of the invention, and/or the above variants thereof, the distance between the web and the inlet opening of the inlet Venturi, and the distance between the web and the inlet opening of the outlet Venturi is from 1 /4 inch to 3/4 inch.
(e) DESCRIPTION OF THE FIGURES
In the accompanying drawings, Fig. 1 is a schematic view of the area of a paper-making machine of a typical prior art installation between the press section and the drying section;
Fig. 2 is a schematic view of the area of a paper-making machine between the press section and the drying section according to an aspect of one embodiment of the present invention;
Fig. 3 is an enlarged view of the sheet transfer stabilizer according to an aspect of one embodiment of the present invention shown in Fig. 2, and Figs. 4 and 5 are graphs which show the performance of the sheet transfer stabilizer according to an aspect of one embodiment of the present invention.
(fj DESCRIPTION OF THE PRIOR ART
Fig. 1 (the prior art) shows three blow boxes one after the other. The blow boxes each have a planar bottom face which is located at a distance O from the opposite drying wire. The distance O is preferably within the range of 10 to 25 mm. At both ends of the planar bottom wall of the blow boxes, nozzle slots are located, by means of which the blow jets are generated. The downstream nozzle slot of the last nozzle box is located substantially at the position at which the drying wire and the paper web achieve contact with the first drying cylinder. The fetching roll may also be arranged as a suction roll, and the suction zone a of the roll is shown in broken lines.
Additional air jets of the blow boxes are directed opposite to the direction of movement of the wire or paper web and of the roll. According to the prior art, it was alleged that the ejection effect of the jets prevented generation of detrimental positive pressures.
(g) ONE MODE FOR CARRYING OUT THE INVENTION
As seen in Fig. 2, one aspect of one embodiment of the present invention provides a sheet transfer stabilizer 10 which is disposed above the felt or fabric 11 between the felt or fabric roll 12 and the first dryer cylinder 13. The sheet transfer stabilizer is in the shape of a box 14, extending transversely across the entire width of the felt or fabric 11 and the web 15. The sheet transfer stabilizer 10 is provided with an inlet Venturi 16, a main Venturi 17 and an outlet Venturi 18.
The detailed internal structure of the sheet transfer stabilizer 10 of Fig. 2 is shown in Fig. 3. As shown in Fig. 3, the inlet Venturi 16 is formed by the surface 20 and surfaces 21,22 which are parallel thereto. Primary air from one nozzle 23 (or from a series of nozzles) is discharged into the throat 24 which is formed by surfaces 20, and 21, 22 . The suction thus created draws air in through opening 25 , as shown by arrows A. The combined air is discharged through inlet discharge opening 26.
Air which is carried along by the felt or fabric 11 is exhausted through the outlet Venturi 17. The outlet Venturi 17 is formed by the surface 30 and surfaces 31, parallel thereto. Primary air from one nozzle 33 (or from a series of nozzles) is discharged into the throat 34 which is formed by surfaces 30 and 31, 32. The suction thus created draws air in through opening 35, as shown by arrow B. The combined air is discharged through outlet discharge opening 36.
The main function of the sheet transfer stabilizer 10 is to create a negative pressure above the felt or fabric 11 so as to keep the web 15 in close contact with the felt or fabric 11. This is primarily achieved by the main Venturi 18. Air is exhausted from the plenum C, by the main Venturi 18. The main Venturi 18 is formed by the surfaces 40,41 and 42,43. Primary air from a nozzle 44 or 45, (or from a series of such nozzles), or from both nozzles 44,45, (or from all of a series of such nozzles), is discharged into the throat 46 which is formed by surfaces 40,41 and 42,43. The suction thus created draws air in through opening 47, as shown by arrow D. The combined air is discharged through main discharge 48 opening.
5 The main Venturi 18, in addition, generates a negative pressure in plenum C
which, in turn, creates a negative pressure over the surface of the felt or fabric 11 between the felt or fabric roll 12 and the dryer cylinder 13.
Air under pressure enters the interior 50, 51 of the sheet transfer stabilizer 10.
By means of dampers 52,53,54,55, primary air to each Venturi nozzle 23,44,45,33, 10 (respectively), may be controlled and, thereby, the amount of exhaust and suction that is generated by the sheet transfer stabilizer 10 can be controlled. In addition, such separate dampers 52, 53 , 54, 55 allow the modulation or biassing of the entrained air volume and suction pressure generated.
A recessed central section between forward wall 60 and rear wall 61 helps to create a plenum effect in order to enhance the effect of the negative static pressure.
Fig. 4 shows the relationship between suction pressure and the distance between the felt or fabric and the sheet transfer stabilizer. Up to 1.0 inches of negative pressure can be developed with a 1/2" gap. This suction, however, drops off rapidly above 1/2".
Consequently, 1/2" has been selected as an optimum operating point.
Fig. 5 shows the amount of induced air from the main Venturi as a function of the distance between the sheet transfer stabilizer and the felt or fabric. The main Venturi has a constant air flow while the flow from the outlet Venturis increase with distance.
As described hereinabove, the aims of the present invention have been met by the sheet transfer stabilizer which provides a direct and measurable relationship between the amount of air supplied and the amount of air entrained. This sheet transfer stabilizer is based on the use of a Venturi. A Venturi is a device in which air with a high static pressure and low velocity is forced through a "throat" where the velocity is increased to a high level. The static pressure is converted to velocity pressure. If the velocity is high enough, the static pressure in the throat can actually become negative. Proper design of the Venturi will ensure that the desired pressure are obtained. Equations governing Venturi design are well known. A Venturi, properly designed, will have a suction that is definitive and quantitative. This suction, in turn, is used to evacuate air from above the felt or fabric and to stabilize the paper sheet.
As described above, the sheet transfer stabilizer of broad aspects of the present invention includes three Venturis, namely an inlet Venturi, an outlet Venturi and a main Venturi. The inlet Venturi is located as close as possible to the felt or fabric roll in order to exhaust air from the area where the felt or fabric separates from the surface of the felt or fabric roll. Air in this region would have the highest tendency to push through the felt or fabric and would cause the initial bubbling and fluttering of the paper sheet.
The outlet Venturi expels a large quantity of air from the gap between the dryer cylinder and the bottom of the sheet transfer stabilizer.
The main Venturi is also designed to expel a large quantity of air and, in conjunction with the outlet Venturi, maintains a negative static pressure over the unsupported span between the felt or fabric roll and the dryer.
The sheet transfer stabilizer of aspects of this invention includes dampers.
Each Venturi has a separate damper which allows the modulation or biassing of the entrained air volume and suction pressure generated.
which, in turn, creates a negative pressure over the surface of the felt or fabric 11 between the felt or fabric roll 12 and the dryer cylinder 13.
Air under pressure enters the interior 50, 51 of the sheet transfer stabilizer 10.
By means of dampers 52,53,54,55, primary air to each Venturi nozzle 23,44,45,33, 10 (respectively), may be controlled and, thereby, the amount of exhaust and suction that is generated by the sheet transfer stabilizer 10 can be controlled. In addition, such separate dampers 52, 53 , 54, 55 allow the modulation or biassing of the entrained air volume and suction pressure generated.
A recessed central section between forward wall 60 and rear wall 61 helps to create a plenum effect in order to enhance the effect of the negative static pressure.
Fig. 4 shows the relationship between suction pressure and the distance between the felt or fabric and the sheet transfer stabilizer. Up to 1.0 inches of negative pressure can be developed with a 1/2" gap. This suction, however, drops off rapidly above 1/2".
Consequently, 1/2" has been selected as an optimum operating point.
Fig. 5 shows the amount of induced air from the main Venturi as a function of the distance between the sheet transfer stabilizer and the felt or fabric. The main Venturi has a constant air flow while the flow from the outlet Venturis increase with distance.
As described hereinabove, the aims of the present invention have been met by the sheet transfer stabilizer which provides a direct and measurable relationship between the amount of air supplied and the amount of air entrained. This sheet transfer stabilizer is based on the use of a Venturi. A Venturi is a device in which air with a high static pressure and low velocity is forced through a "throat" where the velocity is increased to a high level. The static pressure is converted to velocity pressure. If the velocity is high enough, the static pressure in the throat can actually become negative. Proper design of the Venturi will ensure that the desired pressure are obtained. Equations governing Venturi design are well known. A Venturi, properly designed, will have a suction that is definitive and quantitative. This suction, in turn, is used to evacuate air from above the felt or fabric and to stabilize the paper sheet.
As described above, the sheet transfer stabilizer of broad aspects of the present invention includes three Venturis, namely an inlet Venturi, an outlet Venturi and a main Venturi. The inlet Venturi is located as close as possible to the felt or fabric roll in order to exhaust air from the area where the felt or fabric separates from the surface of the felt or fabric roll. Air in this region would have the highest tendency to push through the felt or fabric and would cause the initial bubbling and fluttering of the paper sheet.
The outlet Venturi expels a large quantity of air from the gap between the dryer cylinder and the bottom of the sheet transfer stabilizer.
The main Venturi is also designed to expel a large quantity of air and, in conjunction with the outlet Venturi, maintains a negative static pressure over the unsupported span between the felt or fabric roll and the dryer.
The sheet transfer stabilizer of aspects of this invention includes dampers.
Each Venturi has a separate damper which allows the modulation or biassing of the entrained air volume and suction pressure generated.
Claims (9)
1. A sheet transfer stabilizer for transferring a wet fibrous paper sheet from a press section to a dryer section of a paper-making machine by way of a felt or fabric, said sheet transfer stabilizer comprising:
i) a Venturi box for stabilizing said wet fibrous paper sheet which is being transferred from said press section to said dryer section of said paper-making machine by way of said felt or fabric, by the generation of negative pressure in the space on the side of said felt or fabric which is opposite to the side of said felt or fabric which supports said web, said Venturi box being disposed between a guide roller of said press section and a first dryer, said Venturi box including three side-by-side Venturis, comprising:
i) an inlet Venturi, said inlet being defined by a pair of spaced-apart, substantially-parallel, forward surfaces, said spaced-apart, substantially-parallel, forward surfaces being angularly-disposed to the plane of said felt or fabric, and including means for generating a flow of at least one jet of air into a space between said spaced-apart, substantially-parallel, forward surfaces, said flow of said at least one jet of air thereby generating a negative pressure at said inlet Venturi, said at least one jet of air then being discharged in an angular direction away from said felt or fabric;
ii) an outlet Venturi, said outlet Venturi being defined by a pair of spaced-apart, substantially-parallel, rear surfaces, said spaced-apart, substantially-parallel, rear surfaces being angularly-disposed to the plane of said felt or fabric, and including means for generating or flow of at least one jet of air into a space between said spaced-apart, substantially-parallel, rear surfaces, said flow of at least one jet of air thereby generating a negative pressure at said outlet Venturi, said at least one jet of air then being discharged in an angular direction away from said felt or fabric; and iii) a main Venturi, said main Venturi being defined by a pair of central, spaced-apart, substantially-parallel surfaces, said central spaced-apart, substantially-parallel surfaces being disposed, either angularly or perpendicularly, to the plane of said felt or fabric, and including means for generating the flow of at least one jet of air into a space between said central spaced-apart, substantially-parallel surfaces, said flow of said at least one jet of air thereby generating a negative pressure at said main Venturi, said at least one jet of air then being discharged in a perpendicular, or in an angular, direction away from said felt or fabric.
i) a Venturi box for stabilizing said wet fibrous paper sheet which is being transferred from said press section to said dryer section of said paper-making machine by way of said felt or fabric, by the generation of negative pressure in the space on the side of said felt or fabric which is opposite to the side of said felt or fabric which supports said web, said Venturi box being disposed between a guide roller of said press section and a first dryer, said Venturi box including three side-by-side Venturis, comprising:
i) an inlet Venturi, said inlet being defined by a pair of spaced-apart, substantially-parallel, forward surfaces, said spaced-apart, substantially-parallel, forward surfaces being angularly-disposed to the plane of said felt or fabric, and including means for generating a flow of at least one jet of air into a space between said spaced-apart, substantially-parallel, forward surfaces, said flow of said at least one jet of air thereby generating a negative pressure at said inlet Venturi, said at least one jet of air then being discharged in an angular direction away from said felt or fabric;
ii) an outlet Venturi, said outlet Venturi being defined by a pair of spaced-apart, substantially-parallel, rear surfaces, said spaced-apart, substantially-parallel, rear surfaces being angularly-disposed to the plane of said felt or fabric, and including means for generating or flow of at least one jet of air into a space between said spaced-apart, substantially-parallel, rear surfaces, said flow of at least one jet of air thereby generating a negative pressure at said outlet Venturi, said at least one jet of air then being discharged in an angular direction away from said felt or fabric; and iii) a main Venturi, said main Venturi being defined by a pair of central, spaced-apart, substantially-parallel surfaces, said central spaced-apart, substantially-parallel surfaces being disposed, either angularly or perpendicularly, to the plane of said felt or fabric, and including means for generating the flow of at least one jet of air into a space between said central spaced-apart, substantially-parallel surfaces, said flow of said at least one jet of air thereby generating a negative pressure at said main Venturi, said at least one jet of air then being discharged in a perpendicular, or in an angular, direction away from said felt or fabric.
2. The sheet transfer stabilizer of claim 1, including a respective damper in an opening in a respective interior wall within the interior of said sheet transfer stabilizer leading to said respective Venturi, each said respective damper being selectively-movable from a fully-open to a fully-closed position thereby to control at least one of:
i) the amount of primary air in said at least one jet of air which is discharged into said inlet Venturi;
ii) the amount of primary air in said at least one jet of air which is discharged into said outlet Venturi;
iii) the amount of primary air in a first jet of air which is discharged into said main Venturi; and iv) the amount of primary air in a second jet of air which is discharged into said main Venturi.
i) the amount of primary air in said at least one jet of air which is discharged into said inlet Venturi;
ii) the amount of primary air in said at least one jet of air which is discharged into said outlet Venturi;
iii) the amount of primary air in a first jet of air which is discharged into said main Venturi; and iv) the amount of primary air in a second jet of air which is discharged into said main Venturi.
3. The sheet transfer stabilizer of claim 1 or claim 2, including a recessed central portion between an inlet end and an outlet end of said sheet transfer stabilizer to help to create a plenum effect in order to enhance the effect of negative static pressure which may be generated.
4. The sheet transfer stabilizer of claim 1, claim 2 or claim 3, wherein the distance between said web and the inlet opening of said inlet Venturi, and the distance between said web and the inlet opening of said outlet Venturi is from 1/4 inch to 3/4 inch.
5. A method for guiding a wet fibrous web from a press section to a drying section of a paper-making machine, comprising the steps of:
passing said wet fibrous web from said press section in an open draw onto a felt or fabric, said felt or fabric passing about a guide roll; and urging said wet fibrous web and said felt or fabric, against each other as a drying wire of said drying section passes from said guide roll to a drying cylinder, by the generation of negative pressure in the space on the side of said felt or fabric, which is opposite to the side of said felt or fabric, which supports said fibrous web;
wherein said negative pressure is generated using the combination of:
i) an inlet Venturi, having an inlet opening and a throat, said inlet Venturi being located adjacent to said guide roll in order to draw up and exhaust air from an area where said web separates from the surface of said guide roll, ii) an outlet Venturi having an inlet opening and a throat, said outlet Venturi being situated adjacent to said drying cylinder to draw away air from a gap between said dryer cylinder and said inlet opening of said outlet Venturi; and iii) a main Venturi having a first inlet opening and second a inlet opening and throat, said main Venturi being disposed between said inlet Venturi and said outlet Venturi to draw away air away from, and to maintain a negative static pressure over, an unsupported span between said guide roll and said dryer cylinder.
passing said wet fibrous web from said press section in an open draw onto a felt or fabric, said felt or fabric passing about a guide roll; and urging said wet fibrous web and said felt or fabric, against each other as a drying wire of said drying section passes from said guide roll to a drying cylinder, by the generation of negative pressure in the space on the side of said felt or fabric, which is opposite to the side of said felt or fabric, which supports said fibrous web;
wherein said negative pressure is generated using the combination of:
i) an inlet Venturi, having an inlet opening and a throat, said inlet Venturi being located adjacent to said guide roll in order to draw up and exhaust air from an area where said web separates from the surface of said guide roll, ii) an outlet Venturi having an inlet opening and a throat, said outlet Venturi being situated adjacent to said drying cylinder to draw away air from a gap between said dryer cylinder and said inlet opening of said outlet Venturi; and iii) a main Venturi having a first inlet opening and second a inlet opening and throat, said main Venturi being disposed between said inlet Venturi and said outlet Venturi to draw away air away from, and to maintain a negative static pressure over, an unsupported span between said guide roll and said dryer cylinder.
6. The method of claim 5, wherein negative pressures at said Venturis are generated at each of said inlet Venturi, said outlet Venturi and said main Venturi, by at least one of:
a) at said inlet Venturi, by expelling a jet of air at a high velocity into the throat of said inlet Venturi and by discharging said jet of air angularly away from the plane of said felt or fabric;
b) at said outlet Venturi, by expelling a jet of air at a high velocity into the throat of said outlet Venturi and by discharging said jet of air angularly away from the plane of said felt or fabric; and c) at said main Venturi by expelling a first jet of air at a high velocity into the throat of said main Venturi and by discharging said first jet of air perpendicularly to the plane of said felt or fabric, or by discharging said first jet of air angularly away from the plane of said felt or fabric.
a) at said inlet Venturi, by expelling a jet of air at a high velocity into the throat of said inlet Venturi and by discharging said jet of air angularly away from the plane of said felt or fabric;
b) at said outlet Venturi, by expelling a jet of air at a high velocity into the throat of said outlet Venturi and by discharging said jet of air angularly away from the plane of said felt or fabric; and c) at said main Venturi by expelling a first jet of air at a high velocity into the throat of said main Venturi and by discharging said first jet of air perpendicularly to the plane of said felt or fabric, or by discharging said first jet of air angularly away from the plane of said felt or fabric.
7. The method of claim 5, or claim 6, wherein the primary air flow is at least one of the following:
a) of from 50 to 200 CPM/ft from said inlet opening of said outlet Venturi into the throat of said outlet Venturi;
b) of from 50 to 200 CFM/ft from said inlet opening of said inlet Venturi into the throat of said inlet Venturi; and c) of from 50 to 400 CFM/ft from said first inlet opening of said main Venturi into the throat of said main Venturi.
a) of from 50 to 200 CPM/ft from said inlet opening of said outlet Venturi into the throat of said outlet Venturi;
b) of from 50 to 200 CFM/ft from said inlet opening of said inlet Venturi into the throat of said inlet Venturi; and c) of from 50 to 400 CFM/ft from said first inlet opening of said main Venturi into the throat of said main Venturi.
8. The method of claim 5, claim 6, or claim 7, wherein negative pressure at said main Venturi is generated by additionally-expelling a second jet of air at a high velocity into the throat of said main Venturi and by discharging said second jet of air perpendicularly to the plane of said felt or fabric, or by discharging said second jet of air angularly away from the plane of said felt or fabric.
9. The method of claims 5 to 8, wherein the distance between said web and the inlet opening of said inlet Venturi, and the distance between said web and the inlet opening of said outlet Venturi is from 1/4 inch to 3/4 inch.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002190563A CA2190563C (en) | 1996-11-18 | 1996-11-18 | Device and method to stabilize sheet between press section and dryer section of a paper-making machine |
| US08/901,556 US5792318A (en) | 1996-11-18 | 1997-07-20 | Method to stabilize sheet between press section and dryer section of a paper-making machine |
| US08/990,917 US5820733A (en) | 1996-11-18 | 1997-12-15 | Device to stabilize sheet between press section and dryer section of a paper-making machine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002190563A CA2190563C (en) | 1996-11-18 | 1996-11-18 | Device and method to stabilize sheet between press section and dryer section of a paper-making machine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2190563A1 CA2190563A1 (en) | 1998-05-18 |
| CA2190563C true CA2190563C (en) | 1999-10-26 |
Family
ID=4159271
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002190563A Expired - Fee Related CA2190563C (en) | 1996-11-18 | 1996-11-18 | Device and method to stabilize sheet between press section and dryer section of a paper-making machine |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US5792318A (en) |
| CA (1) | CA2190563C (en) |
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| DE19821542C2 (en) * | 1998-05-14 | 2000-05-11 | Langbein & Engelbracht Gmbh | Blow box |
| EP1127978B1 (en) * | 2000-02-26 | 2006-01-04 | Voith Paper Patent GmbH | Vacuum belt conveyor |
| US6513263B2 (en) | 2000-10-06 | 2003-02-04 | Enerquin Air Inc. | Ventilator for offset pocket and method of ventilating the same |
| US6412192B1 (en) | 2001-01-30 | 2002-07-02 | Enerquin Air Inc. | Device and method for ventilating an offset pocket space in a papermaking machine |
| US6725569B2 (en) | 2001-01-30 | 2004-04-27 | Enerquin Air Inc. | Device and method for ventilating an offset pocket space in a papermaking machine |
| FI111280B (en) * | 2001-11-08 | 2003-06-30 | Metso Paper Inc | Blow box to control web flow |
| CN107254796B (en) * | 2017-08-09 | 2024-02-02 | 玖龙纸业（太仓）有限公司 | Dry net cleaning device |
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| FI72159C (en) * | 1981-05-07 | 1987-04-13 | Valmet Oy | KOMPAKT PRESSPARTI I PAPPERSMASKIN. |
| US4414757A (en) * | 1981-10-07 | 1983-11-15 | Overly, Incorporated | Web dryer nozzle assembly |
| DE3236576C2 (en) * | 1982-10-02 | 1988-03-24 | J.M. Voith Gmbh, 7920 Heidenheim | Air guide box for the dryer section of a paper machine |
| FI67107C (en) * | 1983-02-07 | 1985-01-10 | Valmet Oy | FOER FARANDE OCH ANORDNING FOER LEDANDE AV PAPPERSBANAN FRAON PRESSPARTIET TILL TORKPARTIET |
| FI68278C (en) * | 1983-03-01 | 1985-08-12 | Valmet Oy | FICKVENTILATIONSANORDNING FOER EN MAONGCYLINDERTORK I EN PAPPERSMASKIN |
| SE450957B (en) * | 1983-05-30 | 1987-08-17 | Flaekt Ab | SEALER AT CYLINDERTORK |
| FI67901C (en) * | 1983-10-03 | 1987-07-20 | Valmet Oy | FOERFARANDE OCH ANORDNING I TORKPARTIET I EN PAPPERSMASKIN VID STYRNING AV BANANS SPETS. |
| FI69332C (en) * | 1984-03-02 | 1986-01-10 | Valmet Oy | ANORDNING I TORKNINGSPARTIET AV EN PAPPERSMASKIN |
| FI68279C (en) * | 1984-03-22 | 1985-08-12 | Valmet Oy | FOERFARANDE OCH ANORDNING FOER ATT HINDRA PAPPERSBANAN ATT FLADDRA I TORKNINGSPARTIET AV EN PAPPERSMASKIN |
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| FI76142C (en) * | 1985-11-14 | 1988-09-09 | Valmet Oy | FICKVENTILATIONSFOERFARANDE OCH -ANORDNING I EN PAPPERSMASKINS MAONGCYLINDERTORK. |
| DE3544541C1 (en) * | 1985-12-17 | 1987-08-06 | Voith Gmbh J M | Device for transferring a paper or cardboard web from the press section to the dryer section of a paper machine or the like |
| AU592978B2 (en) * | 1986-02-21 | 1990-02-01 | Beloit Corporation | Preventing sheet flutter in paper web dryers |
| US4698919A (en) * | 1986-04-08 | 1987-10-13 | Beloit Corp. | Apparatus for assisting the transfer of a web to a drying section |
| FI74312C (en) * | 1986-08-22 | 1988-01-11 | Valmet Oy | METHOD OCH ANORDNING FOER EN PAPPERSMASKINS VIRAPARTI. |
| FI80103C (en) * | 1987-06-17 | 1990-04-10 | Valmet Paper Machinery Inc | Method and apparatus in the cylinder dryer of a paper machine, in which a double-weave pull is used |
| CA1307107C (en) * | 1987-06-22 | 1992-09-08 | Pekka Eskelinen | Pocket ventilation method for the drying section of a paper machine, particularly for fast paper machines |
| FI80491C (en) * | 1987-09-02 | 1990-06-11 | Valmet Paper Machinery Inc | FOERFARANDE OCH TORKNINGSGRUPP I MAONGCYLINDERTORKEN AV EN PAPPERSMASKIN. |
| FI77119C (en) * | 1987-09-23 | 1989-01-10 | Valmet Paper Machinery Inc | FOERFARANDE OCH ANORDNING FOER MAETNING AV LUFTGENOMSLAEPPNINGSFOERMAOGAN HOS LUFTGENOMSLAEPPLIGA VAEVNADER I SYNNERHET EN VIRA ELLER EN FILT I EN PAPPERSMASKIN. |
| DE3807856A1 (en) * | 1988-03-10 | 1989-09-21 | Voith Gmbh J M | METHOD FOR DRYING A MATERIAL RAIL AND DEVICE FOR CARRYING OUT THIS METHOD |
| FI80102C (en) * | 1988-07-01 | 1990-04-10 | Tampella Oy Ab | FOERFARANDE OCH ANORDNING FOER TORKNING AV EN FIBERBANA. |
| US4875976A (en) * | 1988-09-27 | 1989-10-24 | Beloit Corporation | Transfer apparatus from press section to drying section |
| US4891891A (en) * | 1988-10-11 | 1990-01-09 | Beloit Corporation | Dryer section apparatus and method |
| CA1316668C (en) * | 1989-09-29 | 1993-04-27 | Remi Turcotte | Pocket ventilator |
| US5022166A (en) * | 1990-06-07 | 1991-06-11 | Union Camp Corporation | Flutter suppression air foils |
| FI95732C (en) * | 1992-01-13 | 1996-03-11 | Valmet Paperikoneet Oy | Device in the dryer section of a paper machine |
| WO1994019535A1 (en) * | 1993-02-19 | 1994-09-01 | Valmet Paper Machinery Inc. | Method and device for ensuring the run of the web in the multi-cylinder dryer of a papermachine |
| CA2118305C (en) * | 1993-02-19 | 1997-09-23 | Pekka Eskelinen | Method and device for ensuring the run of the web in the multi-cylinder dryer of a papermachine |
-
1996
- 1996-11-18 CA CA002190563A patent/CA2190563C/en not_active Expired - Fee Related
-
1997
- 1997-07-20 US US08/901,556 patent/US5792318A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2190563A1 (en) | 1998-05-18 |
| US5792318A (en) | 1998-08-11 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20151118 |