JPH076156B2 - How to dry a web traveling through the dryer section of a papermaking machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of drying a web moving therethrough. In particular, the invention relates to a method of drying a web moving a dryer section having a plurality of lower dryer drums and a plurality of upper dryer drums.

Information Disclosure Statement When the formed paper web emerges from the press section of a papermaking machine, the formed web still contains a large amount of moisture. Most of this moisture is removed from the formed web as the web passes through the dry section of the papermaking machine. The dryer section typically has a plurality of dryer drums over which the formed web moves. When the web is in intimate contact with the heated outer surface of the dryer drum, the web is heated so that at least some of the moisture contained therein is removed from the web.

The so-called "uni run" or "uno run"
run) "The dryer section typically has upper and lower dryer drums. Each upper and lower stage consists of multiple heated, rotating dryer drums. Alternate windings between upper and lower dryer drums. The felt moves in shape and the web is pressed into physical contact with the heating surface of every other dryer drum as it passes through the dryer section. Although the web is supported by felt, such a conventional system has the following drawbacks.

First, each dryer drum placed every other
Having a support felt located between the heated surface of the dryer drum and the web, the web makes physical contact with only every other heated dryer drum located while passing through the dryer section. Secondly, with the felt placed between the web and the heating surface of the dryer drum, the web moves around the dryer drum, so that the web is thrown out by centrifugal force and at the nip by a pneumatic wedge. The web tends to move away from the felt.

German patent publication 1,931,922, issued on January 21, 1971, of Voith, shows a dryer section with rows of dryers in the upper and lower rows. However, although the lower felt 7 is partially wound around the lower dryer and moved, the lower felt 7 is not provided with a felt wound around the upper dryer. Therefore, the German West German Patent Publication No. 1,931,922
The lack of upper felt causes various running instability problems.

Accordingly, the present invention overcomes the aforementioned problems associated with the prior art by providing a unique method of drying a web through upper and lower dryers. Unlike the conventional "Uniran" system, the present invention has separate upper and lower felts which allow the upper felts to move around the upper dryer drum and the upper intermediate roll in an alternating manner. To Similarly, the lower felts alternate between each lower dryer drum and the lower intermediate roll. In the present invention, both upper and lower intermediate rolls are arranged to be wound by both felt and web. Such an arrangement causes the web to move in an open draw between each adjacent upper dryer drum and lower dryer drum so that the web passes in close contact with the heating surfaces of each upper and lower dryer drum. Moreover, the unique configuration described above minimizes the unsupported travel of the web between adjacent upper and lower dryer drums.

Therefore, the first object of the present invention is to overcome the above-mentioned drawbacks of the prior art, not only the formed web is in close contact with the heating surface of each dryer drum, but also the adjacent upper dryer drum and lower dryer drum. It is to provide a method of drying a web through a dryer section which minimizes open draw between.

Another object of the present invention is a dryer in which second lower intermediate rolls are arranged between adjacent lower dryer drums so that every other second lower intermediate roll guides both the web and the lower felt. It is to provide a method of drying a web passing through a portion.

Another object of the present invention is that every other upper intermediate roll guides both the web and the felt so that the web is open-drawn between the upper dryer drum and the lower dryer drum. So that each of the upper intermediate rolls is positioned between adjacent upper dryer drums, thereby minimizing the length of the open draw and allowing the web to flutter while being fed between the upper and lower dryer drums. It is to provide a method for drying a web through a dryer section so as to prevent (flutter).

Another object of the present invention is to provide a method for drying a web in which an upper intermediate roll and a second lower intermediate roll for guiding both the web and the felt are vacuum rolls.

Another object of the present invention is to provide a method for drying a web in which the upper intermediate roll and the second lower intermediate roll are grooved rolls.

Another object of the invention is to locate the second lower intermediate roll, which guides both the web and the felt, at a first distance from the second upper intermediate roll, which guides only by the upper felt. It is to provide a dryer web drying method. A second lower intermediate roll that guides only the lower felt is positioned adjacent a second upper intermediate roll that guides both the web and the upper felt at a second distance, the second distance being the first distance. It is equal to or greater than the first distance.

Another object of the present invention is to form a pocket by an upper intermediate roll and a second lower intermediate roll that guide the felt and the web, and arrange a blow box in each pocket to ventilate each pocket. It is an object of the present invention to provide a method for drying a web so as to exclude boundary air flowing into the web.

Another object of the invention is to have a plurality of doctor blades, each blade cooperating with a corresponding dryer drum of the upper and lower dryer drums such that each blade contacts the non-surrounding surface of each respective drum. It is to provide a method for drying a web.

Another object of the present invention is to provide a method of drying a web in which the doctor blade helps to stabilize the web by eliminating the effects of outside airflow. The blades also serve to guide the tail of the web during web threading without the use of ropes.

Another object of the present invention is to provide a method for drying a web in which a duct is arranged near the lower intermediate roll which guides only the lower felt. The duct blows air through the lower felt to ventilate adjacent dryer pockets formed between the upper and lower felts with minimal blowing of air.

Another object of the invention is to have a ventilator located near an upper intermediate roll which guides only the upper felt and is only partially surrounded by the upper felt, the ventilator comprising an upper felt and a lower felt. To provide a method for drying a web such that air is blown through the upper felt to ventilate air from adjacent dryer pockets formed between the.

Other objects and advantages of the present invention will be apparent to those skilled in the art from the detailed description given below with reference to the accompanying drawings.

SUMMARY OF THE INVENTION The present invention relates to a method of drying a web moving therethrough. The present invention has a plurality of lower dryer drums and a plurality of upper dryer drums, and further has a lower felt that partially surrounds each lower dryer drum of the plurality of lower dryer drums. The present invention also includes a plurality of lower intermediate rolls, wherein every other one of the lower intermediate rolls has a second lower intermediate roll adjacent to the lower dryer to guide both the web and the lower felt. It is placed between the drums. The upper felt partially surrounds each upper dryer drum of the plurality of upper dryer drums. The present invention has a plurality of upper intermediate rolls, and an upper intermediate roll disposed between the first upper dryer drum and the second upper dryer drum guides both the web and the upper felt.

The web is guided in an open draw from the first lower dryer drum such that the web wraps around and around the first upper dryer drum such that the web is located between the first upper dryer drum and the upper felt.

The combined web and top felt travel around an upper intermediate roll and then around a second upper dryer drum. The unsupported web is then moved from the second upper dryer drum to the second lower dryer drum such that the upper felt is guided around the second upper intermediate roll and the web is positioned between the second lower dryer drum and the lower felt. Move around and around. Then, the web is in close contact with each heating surface of the heating dryer drum, so that the distance that the web moves between adjacent dryer drums without being supported is the shortest,
The combined web and lower felt are both moved around a second lower intermediate roll towards a third lower dryer drum.

As described above, the web is sent by the open draw between the adjacent upper dryer drum and the lower dryer drum, thereby minimizing the length of the open draw,
Flapping of the web can be prevented during transfer between the upper dryer drum and the lower dryer drum.

In a particular embodiment of the present invention, the lower felt presses the web so that when the lower dryer drum is heated, the web is pressed against the lower drum so that the web physically dries with the lower dryer drum. Contact with. The lower felt includes a lower intermediate roll disposed between each adjacent lower dryer drum and a first lower dryer drum and a second lower dryer drum, and a lower intermediate roll disposed between a second lower dryer drum and a third lower dryer drum. 2 Extends in a serpentine shape between the lower intermediate rolls. Every other second lower middle roll, which guides both the web and the lower felt, is arranged near the second upper middle roll which is partly surrounded by the upper felt only. Every other second lower intermediate roll is a vacuum roll.

Each of the second lower intermediate rolls, which guide both the web and the lower felt, are arranged at a first distance from the second upper intermediate roll, which guides only the upper felt. Each lower intermediate roll that guides only the lower felt is located a second distance from an adjacent upper intermediate roll that guides both the web and the upper felt. The second distance is the first
Set to be equal to or greater than the distance.

A second lower intermediate roll that guides the lower felt and the web and is partially surrounded by the lower felt and the web, and an upper intermediate roll that guides the upper felt and the web and is partially surrounded by the web form a pocket. To do. Blow boxes located in each pocket ventilate each pocket and remove boundary air entering the pocket.

Upon heating of the upper dryer drum, the upper felt presses the web such that the web pressed against the upper dryer drum dries, causing the web to make physical contact with the upper dryer drum. The upper felt moves in a serpentine fashion between each adjacent upper dryer drum and upper intermediate roll and the second upper intermediate roll.

Every other upper intermediate roll, which guides both the web and the upper felt, is arranged adjacent to the lower intermediate roll, which guides only the lower felt and is partly surrounded by the lower felt. Each upper roll placed in turn is a vacuum roll.

The present invention also provides a plurality of doctor blades, each blade cooperating with a corresponding dryer drum of the upper and lower dryer drums such that it contacts the non-surrounding surface of each respective drum. Those blades are
Not only does it stabilize the web by eliminating the effects of outside airflow, but it also orients the web while the web is threaded through the device without the use of ropes.

A duct is arranged near the lower intermediate roll that guides only the lower felt and is partially surrounded by the lower felt. This duct blows air through the lower felt to ventilate adjacent dryer pockets formed between the upper and lower felts.

A ventilation means is arranged adjacent to the second upper intermediate roll, which guides only the upper felt and is partially surrounded by the upper felt. The ventilation means blows air through the upper felt to ventilate air from adjacent dryer pockets formed between the upper and lower felts.

In another embodiment of the invention, the vacuum roll is replaced with a grooved roll.

As explained in the above description, although the present invention has shown vacuum rolls to be intermediate rolls as grooved rolls, the present invention is not limited to such rolls, such as pocket ventilation rolls, vent rolls, A grooved roll or the like can also be used. Although the present invention has been described with reference to certain specific details particularly in the detailed description which follows, various modifications can be made to the invention without departing from the spirit and scope of the claims. It will be apparent to those skilled in the art that such variations are within the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a conventional dryer section showing the upper and lower felts and the web moving in an open draw over a long distance between adjacent upper and lower dryer drums. 2 is a side view of FIG. 2 and is similar to FIG. 1, but in order to increase the number of dryer drums arranged within a given length of dryer section, the upper dryer drums are separated from each other. How to approach is shown in the conventional arrangement of FIG.

FIG. 3 shows a so-called “approaching type” in which the vertical distance between the upper and lower stages of the dryer drum is shortened, thereby shortening the non-support distance for moving the web between the upper dryer drum and the lower dryer drum. (Squat typ
e) "shows a dryer section. The figure also shows that the distance between adjacent upper dryers has been increased, which has reduced the number of dryer drums arranged within a given length of dryer section. Indicates the status.

FIG. 4 is a cross-sectional view of a dryer sub-device according to the present invention showing an "approximated" arrangement, which minimizes the distance between adjacent upper and lower dryer drums and also between adjacent upper and lower dryer drums. The state where the distance that the web moves in the unsupported state is minimized is shown.

FIG. 5 is a drawing similar to FIG. 4, showing a distance D6 equal to the distance D7.

Like numbers refer to like parts throughout the drawings.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a conventional dryer section generally designated by 10 showing an upper felt 12 and a lower felt 14 with a web W adjacent upper dryer drums 16, 18 and a lower dryer. Move with drum 20 over a long distance in an open draw. As shown in FIG. 1, the upper felt 12 does not move around the lower drum 20 as in a "Unilan" type system, but rather as an intermediate roll 22.
Move around. Similarly, lower felt 14
Moves around the lower intermediate roll 24 and then in a serpentine manner around the lower dryer drum 20 so that the web W has the lower felt 14 and the outer surface 26 of the lower dryer drum 20.
Be placed between and. The lower felt 14 then moves around another lower intermediate roll 28.

FIG. 2 is a drawing similar to FIG. 1, but showing how the upper dryer drums 16A and 18A are brought closer together in order to increase the number of dryer drums within a given length of dryer section. Shown in the conventional arrangement of FIG.

FIG. 3 shows that the vertical distance D1 between the upper stage 30 and the lower stage 32 of the dryer drums 16B, 18B, 20B is shortened so that the web WB moves between the upper dryer drum 16B and the lower dryer drum 20B. Fig. 7 shows a so-called "approach" dryer section with a reduced non-support distance. FIG. 3 also shows that the distance D2 between adjacent upper dryer drums 16B and 18B is increased compared to the distance D3 between the upper drums 16A and 18A of FIG. It shows that the number of dryer drums that can be placed within a given range has decreased.

FIG. 4 is a cross-sectional view of a dryer partial device 10C according to the present invention. FIG. 4 shows a "close-up" arrangement, but with a minimum distance between adjacent upper dryer drums 16C and 18C. This arrangement also minimizes the distance D5 that the web WC travels between the adjacent upper dryer drum 16C and lower dryer drum 20C in an unsupported state.

In particular, the dryer sub-device 10C shown in FIG. 4 is used to dry the web WC traveling therethrough. The device 10C includes a plurality of lower dryer drums 20C, 34, 36.
And a plurality of upper dryer drums 16C, 18C, 38.
The device 10C includes a lower felt 14C that partially surrounds each of the lower dryer drums 20C, 34, 36 of the plurality of lower dryer drums.
Have. The plurality of lower intermediate rolls 24C, 28C, 40, 42 are arranged such that each lower intermediate roll 24C, 28C, 40, 42 is arranged between the adjacent dryer drums 20C, 34, 36. The lower intermediate roll 28C is arranged between the adjacent dryer drums 20C and 34, and the lower intermediate roll 40 is arranged between the adjacent dryer drums 34 and 36. Every other (interlaced) lower middle roll 40 guides both the web WC and the lower felt 14C. Upper felt 12C
Partially surrounds each upper dryer drum 16C, 18C, 38 of the plurality of upper dryer drums. Multiple upper intermediate rolls 4
4,22C, 46 are arranged such that each upper intermediate roll 44,22C, 46 is located between adjacent upper dryer drums.
The upper roll 22C is arranged between the dryer drums 16C and 18C, and the upper intermediate roll 46 is arranged between the adjacent upper dryer drums 18C and 38. Every other upper intermediate roll, such as roll 22C, is guided in both web WC and upper felt 12C, so that web WC is adjacent lower dryer drum 20C and upper dryer drum 16C. Is transferred by an open draw 48 to and from it, which minimizes the length D5 of the open draw 48 and prevents flutter of the web as it travels between the upper and lower dryer drums. To prevent.

In the dryer partial device 10C, the lower felt 14C presses the web to physically contact the lower dryer drum 20C, and when the lower dryer drums 20C, 34, 36 are heated, the lower felt drums 20C, 34, 36 are pressed. Web WC
Are arranged to dry. Lower felt 14C moves in a serpentine fashion between each adjacent lower dryer drum 20C, 34, 36 and lower intermediate roll 24C, 28C, 40, 42.

Every other lower intermediate roll 40 is placed adjacent to an upper intermediate roll 46 which is only partially wrapped by the upper felt 12C. Each lower intermediate roll placed every other roll 24C, 28C, 40, 42 is a vacuum roll.

The lower intermediate roll 40, which guides both the web WC and the lower felt 14C, is arranged at a first distance D6 with respect to the upper intermediate roll 46 which is partly surrounded by the upper felt 12C. Each of the lower intermediate rolls, such as 28C, that are partially wrapped only by the lower felt 14C, has a second distance D7 relative to an adjacent upper intermediate roll 22C that is partially wrapped by both the web WC and the upper felt 12C. Will be placed. The second distance D7 is longer than the first distance D6.

Partly surrounded by lower felt 14C and web WC,
Each lower middle roll, for example 40, and upper felt 12
C and each upper intermediate roll, such as 22C, which is partially surrounded by the web WC, forms pockets 50, 51, respectively. The blow box, shown generally at 52, has a pocket of 51
Is vented to eliminate boundary air flowing into the pocket 51 as indicated by arrow 54.

Since the upper felt 12C presses the web WC to physically contact the upper dryer drums 16C, 18C, 38, when the upper dryer drums 16C, 18C, 38 are heated, the web WC pressed against the upper dryer drum is dry. The upper felt 12C moves in a serpentine fashion between each adjacent upper dryer drum 16C, 18C, 38 and the upper intermediate roll 44, 22C, 46.

Every other upper intermediate roll, e.g. 22C, which guides both the web WC and the upper felt 12C, is positioned adjacent to the lower intermediate roll 28C which is partially surrounded by the lower felt 14C only. To be done. Every other upper roll, such as 22C, is a vacuum roll.

The dryer partial device 10C includes a plurality of doctor blades 56,
It has 57,58,59. Each blade of multiple blades 56-59
Cooperate with the corresponding dryer drums 16C, 18C, 34, 36 of the upper and lower dryer drums to contact the non-surrounding surfaces 60, 61, 62, 63 of each drum 16C, 18C, 34, 36. Blades 56-59 stabilize the web WC by preventing the effects of outside airflow. In addition, the blades 56-59 guide the tail (not shown) of the web while the web is threaded through the device without the use of rope.

As shown in FIG. 4, the device 10C also includes a lower felt 1
It has a duct 64 located adjacent to each lower intermediate roll, such as 28C, which is only partially surrounded by 4C. This duct 64 has an upper felt 12C and a lower felt 1
Blow air through the lower felt 14C (as indicated by arrow 66) to ventilate the adjacent dryer pocket 67 formed between it and 4C. This device 10C also includes ventilation means 68.
This means is located adjacent to each upper intermediate roll, for example 18C, which is only partially wrapped by the upper felt 12C. Ventilation means 68 expels air through the upper felt 12C (as indicated by arrow 70) to expel air from an adjacent dryer pocket 72 formed between the upper felt 12C and the lower felt 14C.

In another embodiment of the invention, the intermediate vacuum roll is replaced by a grooved roll.

FIG. 5 is a side view of the same dryer sub-device as the dryer device shown in FIG. 4, except that the distances D8 and D9 are the same, where D7 is greater than D6 in the device of FIG.
This arrangement increases the length of wrap around the felt dryers 20D and 34D.

In operation of the dryer sub-device 10C, the tail (not shown) of the web WC is guided between the lower felt 14C and the lower dryer drum 20C as the web passes through the device. The web is on the outer surface 26C of the lower dryer drum 20C.
Is heated by direct contact with and passes around it with a short open draw D5 towards the upper dryer drum 16C, the web WC being located between the upper felt 12C and the outer surface of the dryer drum 16C. The combined felt 12C and web WC moves around the upper intermediate roll 22C so that the felt 12C and the web WC move together around the upper dryer drum 18C. In the blow box 52, the boundary air accompanying the drum 16C is in the pocket 5
Spray the air curtain in the direction indicated by arrow 74 so that it does not enter inside. After the upper felt 12C partially surrounds the drum 18C, the upper felt 12C is rotated around the upper intermediate roll 46 to form a web.
The WC then moves with the drum 18C, is guided by the doctor 57 and contacts the outer surface of the lower dryer drum 34.
The tail is guided between the lower felt 14C and the drum 34, and the felt 14C and the tail of the web travel around the lower intermediate roll 40 and then around the drum 36. The tail of the web is an open draw and moves towards and around the upper drum 38 between the drum and the upper felt 12C, at which time the lower felt 14C is moved to another lower intermediate roll 42. Move around.

When the web is threaded, the speed of rotation of the drum increases to the operating speed, and the web is in close contact with its heating surface over most of the perimeter of each dryer drum, and each dryer drum 20C, 16C, 18C, 34, Move around 36,38. In addition, the distance the web moves in an open draw between the adjacent upper and lower dryer drums.
D5 is minimized, thereby eliminating the possibility of sheet flapping between adjacent dryer drums. In addition to this, due to the above-described shape, the number of upper and lower dryer drums contained within a given length of dryer section is such that the web and felt are wound around every other intermediate roll arranged. Increase by wrapping both.

The present invention provides a method of drying a web in a compact form that allows the heating capacity of each dryer drum to be maximized within the dryer section. The present invention also provides ample room for containing a doctor blade adjacent each individual dryer drum. In addition, the flapping of the sheet is significantly reduced because the distance the unsupported web travels between adjacent dryer drums is minimal.

Claims (14)

[Claims] 1. A web is guided between a lower felt and a first lower dryer drum; and a web toward the first upper dryer drum such that the web is positioned between the first upper dryer drum and the upper felt. Guide the web in an open draw around it; move the combined web and upper felt around an upper intermediate roll and then around a second upper dryer drum; then move the upper felt to a second upper intermediate. Guide around rolls; move unsupported web from second upper dryer drum to second lower dryer drum around it so that web is located between second lower dryer drum and lower felt Then, the web is brought into close contact with each heating surface of the heating dryer drum, Moving the combined web and lower felt together around the second lower intermediate roll towards the third lower dryer drum so that the web has the least distance to move unsupported; A method of drying a web traveling through a dryer part of a machine. 2. The lower felt, when the lower dryer drum is heated, presses the web so that the web pressed against the lower dryer drum dries so as to make physical contact with the lower dryer drum. Are arranged between adjacent lower dryer drums and lower intermediate rolls arranged between the first lower dryer drum and the second lower dryer drum, and between the second lower dryer drum and the third lower dryer drum. Second
The method for drying a web according to claim 1, wherein the web is moved in a meandering manner between the lower intermediate roll and the lower intermediate roll. 3. Alternating second lower intermediate rolls for guiding both the web and the lower felt adjacent to the second upper intermediate rolls for guiding only the upper felt, and The method for drying a web according to claim 1, wherein the second lower intermediate roll is a vacuum roll. 4. The web drying method according to claim 1, wherein the second lower intermediate roll is a grooved roll. 5. The second lower intermediate roll that guides both the web and the lower felt is disposed at a first distance from the second upper intermediate roll that guides only the upper felt, and the second lower intermediate roll is disposed. A lower intermediate roll that guides only the felt is disposed at a second distance from an adjacent upper intermediate roll that guides both the web and the upper felt, and the second distance is longer than the first distance. 4. The method for drying a web according to item 3 above. 6. The second lower intermediate roll that guides both the web and the lower felt is disposed at a first distance from the second upper intermediate roll that guides only the upper felt, and the second lower intermediate roll is disposed. The lower intermediate roll that guides only the felt is disposed at a second distance from the adjacent upper intermediate roll that guides both the web and the upper felt, and the second distance is the same as the first distance. The method for drying a web according to claim 3, wherein 7. The web according to claim 1, wherein the second lower intermediate roll guiding the lower felt and the web and the upper intermediate roll guiding the upper felt and the web form a pocket. How to dry. 8. A method for drying a web according to claim 7, wherein a blow box arranged in each pocket ventilates each of the pockets and eliminates boundary air flowing into the pockets. 9. The upper felt presses the web into physical contact with the upper dryer drum so that the web pressed against the upper dryer drum dries when the upper dryer drum is heated. Is the upper dryer drum and the upper intermediate roll and the second
The method of drying a web according to claim 1, wherein the web is moved in a meandering manner between the upper intermediate roll and the upper intermediate roll. 10. A second upper intermediate roll that guides both the web and the upper felt, every second upper intermediate roll, and adjacent to a lower intermediate roll that guides only the lower felt. The method for drying a web according to claim 1, wherein is a vacuum roll. 11. A plurality of doctor blades are further provided, each blade of said plurality of blades being associated with a corresponding dryer drum of upper and lower dryer drums such that said blades contact the non-surrounding surface of each respective drum. A method of drying a web according to claim 1 which works. 12. The web according to claim 11, wherein said blade stabilizes the web by eliminating the influence of outside air flow, and said blade also guides the tail of the web during threading of the device without the use of ropes. The method for drying a web according to the item. 13. A duct is disposed adjacent to a lower intermediate roll that guides only the lower felt, and the duct is formed between the upper felt and the lower felt by blowing air through the lower felt. The method for drying a web according to claim 1, wherein the adjacent dryer pocket is ventilated. 14. A ventilator is disposed adjacent to the upper intermediate roll that guides only the upper felt, the ventilator blowing air through the upper felt to provide a space between the upper felt and the lower felt. Claim 1 for ventilating air from adjacent dryer pockets formed in the
The method for drying a web according to the item.