JPS5870794A - High speed paper web dryer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to improvements in the drying of paper webs, and more particularly to a new and improved drying section of a paper machine.

As paper production, especially lightweight newsprint and lightweight address book paper, becomes faster, the first dryer, which accepts the wet paper just after it has been felted and is still brittle, needs to be stabilized. Manufacturing speeds are 3,000 feet (900 meters) or more per minute or more.Wet webs are fragile because the web is fragile.
It is supported by a porous, permeable belt means running with the web, often referred to as felt or mesh.

In the drying section, the web in contact with the belt means travels at high speed in a serpentine path winding around the rolls on the drying roll.

As described in U.S. Pat. No. 3,956,832, a drying section includes a dual web-carrying belt system and heated air drawn through a Pelto-carrying web wrapped around a perforated roll. A perforated drying roll is used.

Other devices are disclosed in US Pat. No. 4,033,049. In the above apparatus, the web runs over and around a pair of spaced-apart heated rolls or rolls with perforated surfaces and a large hollow peripheral perforated drum, and heated air is directed between the web and the web. Multi-stage drying takes place by directing it through a carrier belt into a drum. The suction chamber is designed to suck humid air from around the drum and roll turns, said device carrying the web in direct engagement with the heated roll surround, and the device carrying the web in direct engagement with the heated roll around the perforated drum. It is described that the leading end of the web is adhesively held on the outside of the mesh provided with spacers. The suction chamber is provided with a partition, said partition extending into the area between the belt and the heating roll, and the space between said partitions is provided with a perforated drum for sucking moist heated air from the drum. It is open to the surrounding area. The above configuration is complex and expensive.

For economy and ease of operation, it is advantageous to use all-solid heated drying rolls arranged in stages with one paper web carrying belt or felt. Such a device is disclosed in US Pat. No. 4,202,113. In this device, air is drawn against a lower grooved drying roll. The dryer roll is then said to hold the paper web on the paper carrier belt as the belt wraps around the lower roll. However, at high operating speeds,
There is a tendency for the wet paper web to separate from the permeable belt as the belt and web move away from the upper roll, around which the paper web is in direct winding engagement.

An important object of the present invention is to overcome the deficiencies, shortcomings, inefficiencies, shortcomings and problems inherent in prior art devices, and to overcome the defects, shortcomings, inefficiencies, shortcomings and problems inherent in prior art devices, and to provide an effective and highly stable method for implementing the device with a single carrier belt. It is an object of the present invention to provide a new and improved paper drying machine that imparts high performance.The present invention is characterized in that a lower roll is installed opposite to a space between a pair of upper rolls, and the web is connected to the first roll. in direct contact and the belt means is in direct contact with the web and the second
The paper web is dried while being interposed between the corrugated rolls,
The web is adapted to run at high speed in a serpentine path winding the roll in contact with a permeable belt means running with the web and having vertically spaced apart and horizontally spaced first
In a dryer section of a paper machine equipped with a stage and a second stage heated drying roll, a pocket is provided along with the entire length of the belt means that runs freely between the lower roll and the pair of upper rolls. means defining a top roll extending between said pair of upper rolls, and a top closure on said pocket; and means for effectively suctioning air into said pocket for holding in contact with belt means.

The present invention also provides a structure in which the lower roll is placed opposite to the space between the pair of upper rolls, the web is in direct contact with the first roll, and the belt means is between the web and the second roll. interposedly, the paper web to be dried is adapted to travel at high speed in a serpentine path winding the roll in contact with permeable belt means traveling with the web;
In the dryer section of a paper machine, which is provided with first and second heated drying rolls that are spaced apart in the vertical direction and are horizontally arranged, the lower roll, the lower roll, and the pair of upper rolls are separated. Air suction is applied to a pocket defined by the entire length of said belt means running freely between the sides of the pocket and the means for closing the top of the pocket, thereby causing air to be drawn from said belt means in the vicinity of the pocket. To provide a drying method characterized in that a web is held in contact with a belt or a stage against the tendency of the web to separate.

Other objects, features and advantages of the invention will become readily apparent from the following description of a few representative embodiments, taken in conjunction with the accompanying drawings. however,
Various changes and modifications may be made without departing from the spirit and scope of novel concepts embodied in the following disclosure.

Referring to FIG. 1, the first dryer section (5) is adapted to receive freshly felted wet paper from a forming device (not shown) and further comprises, in a self-supporting condition, The web is sufficiently dried to be processed, and the dried web is transferred to subsequent processing equipment as desired and customary depending on the particular type of web being processed. For example, the paper web may be lightweight newsprint, lightweight directory paper, or the like. The production of such lightweight paper may be carried out at speeds of 3000 feet per minute (900 meters) or more. It is desirable that this be done at a speed of

At the inlet end of the dryer section (5), the wet paper web (7) joins and runs together with permeable carrier belt means (8). The belt means may be of the type commonly referred to as mesh, wire or felt. As is customary, the belt (8
) runs on appropriate guide rollers outside the pressing section,
It then runs over guide rollers (9) which are essentially the first point of contact with the paper web at the inlet end of the dryer section. Then, the belt (8) running together with the paper web (the force is applied to the upper heated drying roll α0 of the 11th stage arranged in a line with intervals in the horizontal direction), and the lower heated drying roll of the 2nd stage dry roll αυ
The lower rolls run at high speed in a meandering roll winding path with - the lower rolls are - horizontally spaced apart from each other, and each vertically located below the space between each pair of drying rolls (QO); Separate the distance. Any suitable construction of solid drying rolls may be used for rolls aQ, συ.

Furthermore, any appropriate means for driving the two rolls together may be used. σ− of one or both stages
The rolls α[, αυ may be solid rolls with grooves, but this
, only the lower roll is shown as having a structure with grooves around the periphery. Solid heated drying rolls and means for driving them are well known in the art and will not be described in further detail herein.

In the dryer section (5), the web (the first stage roll Q
The belt (8) is in direct winding contact with the second roll α
The web (7) and belt (8) are in close contact with the roll αυ, i.e., the belt (8) is in direct winding contact with the roll αυ. Means (not shown) for surrounding the dryer section (5) -
It will be appreciated that as the nibs progress through the dryer, moisture is removed from the web by the heated drying rolls, so a humid air evacuation device is provided.

When the web is processed in the dryer (5), there is a risk that the web (force) is easy to break due to the high moisture content and low tensile strength. For example, the web (7) and the permeable belt (8) ) leaves the first roll αQ, the surface tension around the upper roll causes the web to become a belt (8).
It tends to peel off and bulge. The above-mentioned tendency to delamination can also occur in other areas of the belt extending between the upper and lower rolls and over the entire length of the web where it runs freely.

In order to avoid said tendency for forces to separate from the web (8), a belt (
8) together with the entire length of the suction pocket means. In order to surround the pocket J, each opposing end wall (to) is combined with both ends of the roll α [, α1, and the closure body α4 is connected to the wall (
It extends between the apex of (to). In a preferred construction,
The side walls are provided with edges cooperating closely with the edges of the belt (8) and may be provided with elastic sealing strips of a suitable low-friction, wear-resistant plastics material. wall (to)
Desirably, the lower edge of the lower edge substantially matches the radius of curvature of the associated lower roll συ and co-moves as closely as possible around the ends of said lower roll. One edge of the wall may carry a suitably low-friction, wear-resistant elastic sealing strip Q71.

As shown in FIG. 1, an elastic sealing means in the form of a groove-shaped rod Oυ is attached to the edge of the top closure body and to the belt section (8) running downwards (upper roll 00) on the left hand side. away from
It is preferable that the belt portion running upward is adjacent to the position where it contacts the right-hand upper roll αQ, and extends along the related upper roll α.

Both the upper and lower edges of the sealing rod (c) are provided with elastic sealing means such as sealing strips 09 of a suitable wear-resistant, low-friction plastic material such as nylon, polytetrafluoroethylene or the like. It is preferable that it be provided. Side weirs or side walls α to avoid excessive wear
30 The various edges and sealing pieces and sealing rods (2) are brought close to the adjacent surfaces to seal as closely as possible, but intentionally not in direct contact. 2 sealing strips (II gives a good seal so that there is no suction loss, the belt (8) outside the suction chamber & 1) extends along both edges of the sealing rod (la)
The web (7) carried by the surface and each upper roll QO
) and the contact angle area (a) between the belt (8
) to ensure a suction effect that holds the web (force).

In order to suck air in '91 pocket α2,
It is desirable to provide a suction opening (A) in at least one of the end weir walls (13).The suction opening is connected to the suction source (2) and the conduit duct.

On the other hand, as shown in FIG. 3, a suction opening (22') may be provided in the top closure α→. As a result, the suction pocket α2 is communicated with the suction generation source through the conduit (E) K.

At web and belt speeds of approximately 3000 feet per minute,
Suction on the order of 0.5 inches of water column is demonstrated for thin, eg, tissue paper. For cardboard, even higher suction forces are used.

For two or three purposes, a first three-roll set, namely a pair of upper rolls σQ and an associated lower roll σ
Suction pockets may be provided only on υ, but for other purposes, as substantially shown in FIG.
A suction pocket may be provided for each roll set.

Through the last of the drying rolls αυ of the lower row, the belt (8) is guided in the return direction by a guide roller (c), at least the drying web (7) being substantially entrained by the guide roller (b). Ru.

It will be understood and understood that various changes and modifications may be made without departing from the spirit and novel concept of the invention.

[Brief explanation of drawings]

Fig. 1 is a schematic side sectional view of the dryer section of a paper machine implementing the present invention, Fig. 2 is a sectional view substantially cut along the plane including the line ■-■ in Fig. 1, and Fig. M3. FIG. 3 is a sectional view showing another embodiment. 5. O dryer section, 7.. Wet paper, 8.. Carrying belt, 9.
・Guide roller, 10・O upper drying roll, 1000 lower drying roll, 12・−suction pocket, 13′−one end wall,
14.0 closure body, 15.17” elastic sealing strip, 18.
Grooved rod, 19.O-sealing piece, 20.2]Oo contact angle area, 22.22'-suction opening. -56(

Claims (1)

[Claims] A lower roll is installed opposite to a space between a pair of upper rolls, the web is in direct contact with the first roll, and a belt means is provided between the web and the second roll. , the paper web to be dried is adapted to travel at high speed in a serpentine path winding the rolls in contact with co-travelling permeable belt means, the paper web being dried at vertically spaced intervals. In a dryer section of a paper machine that is equipped with first and second heating drying rolls in the horizontal direction, the belt runs freely between the lower roll and the pair of upper rolls. The total length of the means and 1
．． means for defining a suction pocket with the web running over the belt means outside the pocket; a top closure extending between the pair of upper rolls and covering the pocket; means for effecting air suction into said pockets to maintain said web in contact with said belt means against the tendency of said web to pull away from said belt means.