JPH05222691A - Dryer for papermaking machine - Google Patents

Abstract

PURPOSE:To provide the subject dryer capable of preventing web wrapping on dryer rolls even in web break and of easily dealing with broke, also capable of shortening apparatus length. CONSTITUTION:In a dryer for papermaking machine to dry wet paper 1 carried on canvas 15 by successive revolutional traveling of plural dryer rolls, such dryer rolls 11 are each equipped inside with a heating means and a hot-air drying device 13 is provided by installing an upper air-exhaust box 14 to dry the wet paper 1 on the upper surface of each roll above each of the dryer rolls 11, and the canvas 15 carrying the wet paper 1 is loaded from below each of the rolls 11 and a suction roll 12 is installed below each of the rolls 11 to ensure the canvas to be unloaded downwardly.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a dryer for a paper machine.

[0002]

2. Description of the Related Art Recently, a dryer roll 1 as shown in FIG.
1 and a suction roll 12 are arranged vertically, and a single canvas type is practically used in which one canvas 15 circulates around and travels to convey the wet paper 1 while drying. However, in the conventional two-sheet canvas type, there is a risk that the wet paper web runs out without being supported by the roll or the canvas.
In this case, this risk is greatly reduced, and since it is always dried in a restrained state, the dimensional stability of the dried paper is improved. That is, in the single canvas type, as shown in FIG. 5, each dryer roll 11 group is composed of only an upper dryer roll or only a lower dryer roll, and a top roll group 23 and a bottom roll group 24 are alternately arranged to form a wet paper web. No. 1 was alternately dried from both sides to avoid the curl problem of the dry paper and the problem of the two-sided smoothness which occur when drying from only one side.

Even the conventional single canvas type,
For the purpose of blocking heat loss from dryer rolls and other high temperature parts to prevent heat loss and improving the surrounding work environment,
At the same time, to prevent the diffusion of evaporated water into the room,
The dryer device is covered with the hood 22, and a fan (not shown)
Is forced to exhaust to the outdoors. Further, the operator must frequently approach the dryer device for the inspection of the device and the treatment after the paper has run out, but this was made possible by making a part of the hood a movable wall.

[0004]

In the above-mentioned conventional single canvas type, since the wet paper web is always held and travels,
Although the risk of paper breakage is reduced, if there are defects created before reaching the dryer device, there is still a possibility of paper breakage due to drying, shrinkage-induced stress, and stress concentration on the defect. It was Further, a doctor 25 is installed in order to prevent the cut paper (hereinafter referred to as "broke") from being wound around the dryer roll 11, and the doctor blade 26 is constantly pressed against the roll to scrape off the broke. In this case, in the top roll (FIG. 6), the scraped-off broke 2 falls naturally, so there is no problem, but in the case of the bottom roll (FIG. 7), the broke 2 first deposits on the doctor 25 [ 7 (a)], the canvas 15 and the dryer roll 11 are eventually drawn into the biting part [FIG. 7 (b)], and the doctor 25 is drawn by this drawing force.
There is a risk that the doctor blade 26 floats up due to the imbalance of the above [Fig. 7 (c)] and the doctor blade 26 cuts the paper 1 and winds it around the roll.

Even if the paper 1 is wound around the dryer roll 11, the top roll group 23 can work from the floor surface 29, so that there is no difficulty in broking, but in the case of the bottom roll group 24, Since the work is performed on the heated dryer roll 11 and in the atmosphere in which the upper part is covered with the hood 22, the removing work is difficult. A small number of operators operate the paper machine while checking the running state of the paper from the floor or the operation room on the operation side. However, the fact that the dryer device is covered with the hood 22 is inconvenient for confirming the traveling state and for approaching the dryer roll 11 for inspection and operation. The present invention eliminates the risk of wrapping around the dryer roll even when the paper runs out, brooke processing, inspection from the operating side,
It is an object of the present invention to provide a dryer for a paper machine, which is easily accessible to the sheet traveling section.

[0006]

For this reason, the present invention provides a dryer for a paper machine, in which a wet paper web is attached to a canvas, and a plurality of dryer rolls are sequentially circulated to dry the wet paper web. A plurality of dryer rolls and a means for drying the wet paper on the upper surface of the rolls are provided above the respective rolls, and the canvas carrying the wet paper is carried in from below the dryer rolls and circulates around the rolls. And a means for carrying it out downwards, which serves as a means for solving the problem.

[0007]

According to the present invention, since the dryer device is made into all top rolls, the curl and the smoothness of the dry paper are two-sided (the smoothness on the upper surface side which does not come into contact with the dryer roll is reduced).
May be a problem, but a hot air drying means is provided in a drying area (hereinafter referred to as a shrinking area) that causes curling,
Balance the drying of the upper and lower surfaces. If a smoothness improving device is provided in the dryer, the smoothness of the upper surface of the wet paper can be improved by pressing with a high temperature smoothing roll. Further, the entire upper part of the dryer roll portion is covered by using the hot air drying means. And, in the gap between the hot air drying means and the floor surface, the drive side portion is blocked by the heat insulating wall,
Except for the part blocked by the structural member on the operating side, the part required for inspection and operation can be left open, and air can be exhausted from the drive side, and this exhausted air is used as the air source for the hot air drying means. Therefore, the length of the dryer device, which is increasing with the speeding up of the paper machine, can be greatly shortened, and the hood and the dryer device can be integrated with each other to achieve compactness and cost reduction.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments of the drawings. FIGS. 1 to 3 show the embodiments of the present invention. In FIG. 1, a dryer device is configured by a top roll group of four groups (# 1 to # 4), and a hot air dryer 13 is installed on each roll as shown in FIG.
An upper exhaust box 14 is provided so as to include the hot air drying device 13 so as to cover the dryer rolls 11 group. The top roll groups are # 1 dryer roll 11 group, # 2 dryer roll 11 group, # 3 dryer roll 11 group, # 4 dryer roll 11 group from the entrance side of the wet paper 1. It was known that the shrinkage due to drying was small up to a water content of about 35% even if there was a difference depending on the raw material, and the dry shrinkage was larger on the dry side. According to the experiments conducted by the present inventors, the problem of curling due to drying occurs when performing unbalanced drying on both sides in this contraction region, and conversely, if balanced drying is performed in this region, I have found that the dry imbalance of is not a problem. The paper moisture of 35% corresponds approximately to the center of the dryer. In the case of the present embodiment, the drying balance in the # 3 and # 4 dryer rolls 11 group is important. The curl size and direction of the dried paper are measured, and the temperature of the hot air device that dries from the upper side of the paper, the wind speed (air volume), and the temperature (vapor pressure) of the dryer roll that dries from the lower side of the paper are controlled. Try to eliminate the curl tendency.

Next, the importance of balanced drying in the shrinkage region will be explained by experiments conducted by the present inventors. Fig. 4 shows a wet paper made with a test paper machine, which is alternately dried from the beginning to the end [Fig. 4 (a)], one half of which is dried first half, and the other half of which is alternately dried [Fig. 4 (b)], all one side. Fig. 4 (c) is a dried product. In the figure, the moisture equilibrium state in the air (water content 9%) → is 6% water content → is overdried → is water content 12
The percentage of humidified → shows the curled state when a drying cycle test is performed to return the moisture to 9% (the horizontal axis shows the drying cycle, the vertical axis shows the reciprocal of the curl radius. In the case of no curl, the curl is shown. The radius is infinite, and the value on the vertical axis becomes zero.) Further, it is shown that the curl is severe in the all-side drying (c), but it is almost equal to the all-alternating drying (a) when the balance drying (b) is performed only in the latter half.

FIG. 2 shows a detailed sectional view of the hot air drying device in FIG. As for the gap between the upper exhaust box 14 and the floor surface in FIG.
Is hung vertically from the upper exhaust box 14. The drive side is closed by a rear side wall 17 so that hot air does not flow in and out, and the front side wall 16 and the rear side wall 17 form a lower exhaust box. It should be noted that the upper air blast box 14 and the lower air blast box are separated from each other except for a gap at the end of the roll and a slight amount of air flowing in and out through the canvas 15. Now, the hot air in the lower exhaust box is extracted by the fan 18 and preheated by the exhaust heat recovery device 19, then heated by the heater 20 and supplied to the hot air drying device 13. The hot air of the upper exhaust box 14 leaking from the hot air drying device 13 passes through the exhaust heat recovery device 19 and is discharged to the atmosphere as exhaust air 3 by the fan 21. In addition to this, in the hot air drying device 13, high-speed air collision is important, and there is a circulation line that is re-supplied after being drawn out from the hot air drying device 13, but this is a technique that has already been implemented, Omit it. As described above, the lower portion of the front side wall 16 on the operation side is open except for the portion closed by the roll and the structural member, but since the air flow is a flow toward the inside of the dryer device, hot air flow is generated. And the evaporated water does not diffuse out of the dryer.

When a paper having a basis weight of 60 g / m ² is currently manufactured at a paper width of 5 m and a paper-making speed of 1200 m / min, if the water discharged from the fan 21 is designed to be 0.12 kg-water / 1 kg-air. The air volume is about 60 m ³ / sec. Front wall 1
6 Assuming that the lower height is 1.4 m and 35% of the height is open, the air flow velocity here is 2.5 m / sec, and it is possible to sufficiently prevent the evaporated water from flowing out. In this way, an open space can be secured on the operating side for inspection and access to the cabin. The hot-air drying device 13 in the # 1 dryer roll group and the # 2 dryer roll group shown in FIG.
Is not essential in the present invention, but in the case of the top roll arrangement as described above, it is easy to incorporate a hot air dryer to integrate the hood, which can improve the operability and also the dryer. There are great advantages such as shortening the device length.

To further explain the present invention, mounting the hot air drying device 13 on a roll is a technique carried out under the name of an air cap in a Yankee machine used for tissues in the paper manufacturing industry. Not detailed. Further, with respect to the group division of the dryer, the whole may be theoretically made into one group, but in practice, it is usually divided into a plurality of groups. In that case, one of the delivery methods between groups of paper
An example is shown in FIG.

Next, FIG. 3 shows an embodiment in which the two-sidedness of the smoothness becomes a problem because only one side is in contact with the dryer roll 11. In the figure, 27 is a metal smooth roll heated to about 100 ° C. to 150 ° C., 28 is an elastic roll,
From the viewpoint of strength and smoothing of wet paper, this device uses paper moisture of 15 to 2
It is desirable that the position is about 5%. As described above, as the most practical example, the embodiment in which the hot air drying device 13 is used has been described, but the main points of the present invention are the upper arrangement of all dryer rolls and the vertical balance drying in the contraction region
Various heating means such as infrared rays, electromagnetic waves or pre-heating of canvas as auxiliary drying means, heating is performed from a roll, evaporation vapor diffusion is performed by high-speed air on the side opposite to the roll to accelerate drying and balance vertically. Means can be considered.

[0014]

As described in detail above, according to the present invention, it is possible to prevent wrapping around the dryer roll even when the paper runs out, facilitate the treatment of broke, and reduce the length of the dryer device. It can be shortened. Further, in the present invention, since a means for drying the wet paper on the upper surface of each dryer roll is provided above each dryer roll, the same means can be integrated with the hood to achieve compactness,
In addition, an open space can always be provided on the operating side for inspection and entrance / exit, which facilitates operation and operation.

[Brief description of drawings]

FIG. 1 is a side view showing a roll arrangement of a dryer for a paper machine according to a first embodiment of the present invention.

FIG. 2 is a detailed front sectional view of a main part in FIG.

FIG. 3 is a side view showing a roll arrangement of a dryer for a paper machine according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an effect when balance drying is performed in a shrinking area in the present invention.

FIG. 5 is a side view showing a roll arrangement of a conventional dryer for a paper machine.

FIG. 6 is an explanatory diagram showing the behavior of broke in the case of a conventional top dryer roll.

FIG. 7 is an explanatory diagram showing the behavior of broke in the case of a conventional bottom dryer roll.

[Explanation of symbols]

 1 Paper 3 Exhaust Air 11 Dryer Roll 12 Suction Roll 13 Hot Air Drying Device 14 Upper Exhaust Box 15 Canvas 16 Front Side Wall 17 Rear Side Wall 18 Fan 19 Exhaust Heat Recovery Machine 20 Heater 21 Fan

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Setsuo Suzuki 5007 Itozaki-cho, Mihara-shi, Hiroshima Mitsubishi Heavy Industries Ltd. Mihara Works (72) Inventor Kazuhito Ohira 5007 Itozaki-cho, Mihara-shi, Hiroshima Mitsubishi Heavy Industries Mihara Works Within

Claims (1)

[Claims] 1. A dryer for a paper machine, wherein a wet paper web is attached to a canvas, and a plurality of dryer rolls are sequentially circulated to dry the wet paper web. A means for drying the wet paper on the upper surface of the roll is provided above, and a means for carrying in the canvas carrying the wet paper from below the dryer roll and circulating the roll to carry out downward. A dryer for a paper machine characterized by: