JPS6367595B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a drying cylinder for a paper making machine or similar machine, and more specifically, to a drying cylinder for a paper making machine or a similar machine, and more specifically, for drying cylinders for drying cylinders for use in paper making machines or similar machines, and more specifically, for drying cylinders for use in paper making machines or similar machines.
This relates to a cylinder that ensures uniform drying.

The cylinder has a casing with grooves cut into its inner surface, and is equipped with a siphon device inside the casing for sucking out condensed water from the grooves.

A siphon device typically consists of many elements. Next, I will explain about it.

A small suction tube protrudes into the area where the condensed water collects, that is, the circumferential groove in the cylinder casing. A large number of small suction tubes for sucking out condensed water are connected to a condensed water reservoir provided in the casing in the axial direction of the casing. A siphon pipe is connected to the condensed water reservoir,
The siphon tube is usually oriented in the radial direction of the casing. This siphon pipe is led into a main condensed water drain line oriented in the axial direction of the casing.

Despite many improvements in papermaking machines, especially in their drying sections, it has always been a problem that it is difficult to maintain uniform wetness or dryness of the paper web over its entire width. It is becoming.

Particularly in large drying cylinders for producing lightweight crepe paper, it is extremely important for the quality and quantity of paper produced that the degree of dryness be uniform over the entire length of the cylinder.

Even slight non-uniformity in the dryness of the paper web has a very undesirable effect on the quality of the paper produced.

Improving the quality of paper produced by paper machines is currently a major research topic in paper machines. Maintaining uniform dryness of paper webs has traditionally been a subject of repeated research.

There are many causes of poor drying conditions.
This research is extremely difficult. Possible causes of this are as follows.

Moisture present in a certain area of the paper web causes that area to become damp. This can be caused by defects in the headbox of the paper machine, such as bent delivery lips, defects in the press members, defects in the wet felt web, blocked holes in the suction rollers, etc.
This is caused by a defect in the injection pipe. In addition, incorrect operation of the hot air guide cylinder is also a possibility. Furthermore, warping of the pressure roller also causes uneven drying.

All of the causes of these disorders have already been studied and at least some of them have been solved. However, making drying completely uniform has not yet been completely solved.

SUMMARY OF THE INVENTION One of the objects of the present invention is to provide a drying cylinder for a paper making machine or similar machine, which can achieve a more uniform degree of dryness in the width direction than before. It is.

Another object of the present invention is to effectively remove condensed water from locations within the casing where large amounts of condensed water tend to collect.

In the present invention, the drying cylinder is arranged in such a way that the drying in the vicinity of the siphon tubes, i.e. the tubes oriented radially from the outside inwards of the casing, is matched with the drying in the remaining longitudinal part of the cylinder casing. It has been devised.

The present invention has been made based on the following recognition.

Conventionally, it has been thought that if the entire siphon device, together with all its parts, is arranged under the same conditions for each suction tube in the groove, the condensed water in each groove can be removed evenly. Heat exchange between the space inside the cylinder and the siphon device has also been considered, but when compared to the total heat consumption required for drying, the amount of heat is very small and does not contribute much. has been confirmed.

Further, it has been thought that if the condensation water reservoir is provided facing the longitudinal direction of the cylinder, this heat exchange will be performed evenly over the entire longitudinal direction of the cylinder.

However, the inventor has noticed that a siphon tube with a relatively large diameter "sweats" a lot on its outer surface. This is because the pressure difference generated inside and outside the siphon tube increases the temperature difference, and as a result, water vapor is particularly likely to condense on the outer surface of each siphon tube.

A large amount of condensed water generated on the siphon tube collects in a groove provided near the siphon tube in the cylinder casing. the result,
The water level of condensed water in these grooves is relatively high.

This causes the said part of the cylinder to be insufficiently dry, and the paper web touching this part remains damp, resulting in so-called "wet streaks".
I can do it.

Many means are conceivable for increasing the dryness in the vicinity of the siphon tube to standard conditions.

One of them is to thermally insulate the siphon tube that connects the condensate reservoir and the axially oriented condensate drain line, that is, the hollow shaft. This reduces the heat exchange between the inner and outer surfaces of the siphon tube and reduces the amount of condensed water that appears in the form of "sweat" on the outer surface of the siphon tube. The amount of condensed water is proportional to the heat transfer coefficient of the tube wall.

The heat transfer coefficient of the siphon tube can be reduced to about 1/10 to 1/100 compared to when the siphon tube is not thermally insulated without spending much money, so the amount of condensed water that adheres can be reduced. is technically reduced to an acceptable level.

Further means may be provided to ensure that the steam does not naturally condense in the remainder of the cylinder and that a satisfactory uniform degree of dryness is obtained over the length of the cylinder. As with the use of a cylinder with a uniform inner wall, the dryness of the paper web can be kept uniform over its entire width. (Cylinders with smooth inner walls have inferior drying ability than cylinders with grooves on the inner surface.) Cylinders with grooves on the inner surface have a paper-making capacity that can only be achieved by maintaining uniform dryness. can be improved.

According to another characteristic of the invention, an insulating coating is provided on the outer surface of the siphon tube between the axially oriented condensation water sump of the cylinder casing and the axially oriented drain line. This is very convenient. This is because if an insulating layer is formed on the inner surface of the tube, there is a risk that the insulating layer will be corroded by the fast flow of fluid.

According to another feature of the invention, the insulating coating is made of, for example, rubber, polyimide or Teflon.
formed of high polymers such as tubes or membranes,
Preferably, it is applied to the tube. If it is tubular, both ends are specially processed so that it can be crimped and sealed to the siphon tube.

According to a further preferred embodiment, the entire outer surface of the insulation sheath of the siphon tube is held by a support casing. This support casing is preferably made of metal. The support casing may be solid or perforated, or may be a helically wrapped tubular or flat material.

According to another embodiment of the present invention, the siphon tube is a double tube, the inner tube and the outer tube form an annular insulating space, and this space is sealed to be as airtight as possible. There is. It is desirable to fill this insulating space only with gas, but it may also be filled with oil, powder, or fibrous insulating fluid.

As mentioned above, there are numerous possible causes of "wet streaks" in paper webs.

Furthermore, it is difficult to find out which part of the paper web in the width direction is the cause of the failure. Even if "wet streaks" appear at specific locations in the width direction of the paper web, it is impossible to identify the cause of insufficient drying. For example, a single "wet streak" may occur due to two factors.

Therefore, for the inventor, the generation of an excessive amount of condensed water in the siphon tube is a "wet streak".
It was not easy to conclude that this was the cause.

The present invention will be described below with reference to embodiments shown in the drawings, which will make other objects and features of the invention clear.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cylinder casing 1 supported at both ends by two caps 2 fixed to a hollow shaft 3. Along the inner surface of the cylinder casing 1, a plurality of annular condensed water reservoirs 4 of a flat closed tube type having a length spanning almost the entire length of the cylinder casing 1 are provided at intervals in the circumferential direction.

FIG. 2 shows a circumferential groove 5 provided on the inner surface of the cylinder casing 1 and a small suction tube 6 protruding into the groove 5. In FIG. 2, a plurality of annular grooves 5 provided on the inner surface of the cylinder casing 1 are shown, and a small suction tube 6 is shown.
has entered some of the grooves 5.

The condensed water reservoir 4 shown in FIG. 2 includes a large number of small suction tubes 6, which are spaced apart from each other so that they project into the grooves 5 every other time.

The suction tube of another condensate sump is not shown in FIG. 2, but as in the adjacent condensate sump,
They are provided at intervals from each other so as to protrude into different grooves. In this way, condensed water is removed equally from all grooves.

In FIG. 1, arrow D indicates steam flowing into the cylinder and arrow K indicates condensed water exiting the cylinder.

The suction pipe 6 sucks the condensed water and carries it out.
It is sent to each condensate water reservoir 4. The condensed water is
From the condensate sump 4 , it flows through a radially inwardly directed siphon pipe 7 into an axially directed condensate drain line 8 located in the center of the casing 1 . Each siphon tube 7 is connected to a respective condensate sump 4.

Each siphon tube 7 is longitudinally movable within a clamping sleeve 12 provided with a sealing ring 13 .

In the embodiment shown in FIG. 1, a heat insulating material 9 is provided on the outer surface of the siphon tube 7. This eliminates the temperature difference between the inner and outer surfaces of the siphon tube 7, which causes condensed water.

In the embodiment shown in FIG. 2, the siphon tube 7 is covered with an outer tube 10. An insulating space 11 is formed between the two tubes 7 and 10, and this space 11 is filled with, for example, gas. This results in
For the reasons mentioned above, the siphon tube 7 is thermally insulated.

In FIGS. 1, 2 and 4, all suction tubules 6 have the same diameter. In FIG. 3, thermal insulation material 9 (or outer tube 10 or insulation space 1
In addition to or instead of 1), the diameter of the suction tube 6a located near the siphon tube 7 is made larger than that of the other suction tubes 6.

When a large amount of condensed water is generated near the siphon tube 7, a large amount of condensed water is sucked out from the grooves 5 near the siphon tube 7, and the water surface of the condensed water in all the grooves 5 is at the same height. is maintained.

A similar effect can be obtained with the embodiment shown in FIG. Here, the diameter of the suction tube 6 is the same. However, the number of small suction pipes 6 near the siphon pipe 7 is greater than in other longitudinal parts of the cylinder casing 1, so that condensed water is effectively absorbed into the grooves 5 near the siphon pipe 7.
sucked out from.

Although the present invention has been described in terms of preferred embodiments thereof, it will be obvious that many changes and modifications may be made by those skilled in the art. It is therefore intended that the invention be limited not only to the embodiments disclosed herein, but rather by the scope of the claims appended hereto.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the drying cylinder of the present invention, in which grooves are cut into the inner peripheral surface. FIG. 2 is a longitudinal sectional view of another embodiment of a cylinder similar to FIG. 1; 3 and 4 are longitudinal sectional views showing two further embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Cylinder casing, 2... Cap, 3... Hollow shaft, 4... Condensed water reservoir, 5... Groove, 6... Suction small pipe, 7... Siphon tube, 8...
... Condensed water drainage pipe line, 9 ... Heat insulation material, 10 ... Outer tube, 11 ... Insulating space, 12 ... Tightening sleeve, 13 ... Seal ring.

Claims (1)

[Scope of Claims] 1. A drying cylinder for a paper-making machine or similar machine, comprising a casing having grooves cut into its inner surface, and an internal space in the drying cylinder for sucking out condensed water from the casing. a siphon device provided in the cylinder, comprising a suction tube projecting into the groove; a condensation reservoir extending parallel to the axis of the cylinder; and a condensation reservoir connected to the condensation reservoir. , and siphon tubes extending generally radially therefrom, said radial siphon tubes adapted to match the drying capacity in the vicinity of said siphon tubes with the drying capacity in the remaining longitudinal area of said casing. A drying cylinder for a paper making machine or similar machine, characterized in that it has sufficient thermal insulation properties. 2. A papermaking machine according to claim 1, characterized in that the radial siphon tubes are provided with an insulating layer covering the outer surface between the condensate reservoir and the condensate drain line. or drying cylinders for similar machines. 3. Drying cylinder for a papermaking machine or similar machine according to claim 2, characterized in that the entire insulation layer is supported on the outside by a casing support. 4. A dryer for a paper making machine or similar machine as claimed in claim 1, wherein the radial siphon tube is double-walled to provide a closed annular insulating space. cylinder. 5. A drying cylinder for a papermaking machine or similar machine according to any one of claims 1 to 4, characterized in that the suction tube has a large diameter in the vicinity of the siphon tube. 6. Paper manufacturing according to any one of claims 1 to 5, characterized in that a larger number of suction pipes are provided near the siphon pipes than in the region along the length of the cylinder casing. Drying cylinder for machines or similar machines.