JP3019416B2 - Paper machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper machine.

[0002]

2. Description of the Related Art Conventionally, a paper machine has a wire part and a press part. In the press part, a wet paper web is placed on a felt and guided, and the moisture in the wet paper is sequentially transferred to the felt side. After the suction press roll was invented as the pre-stage dewatering device of the press part in 1931, one or several stages of suction press rolls were interposed between the wire part and the press part, and the moisture of the wet paper was compressed by the compression roll. A method of compressing and squeezing, and draining the squeezed water immediately from a suction box arranged in a suction roll using felt as a filter material is widely used.

[0003]

However, the above-mentioned conventional suction press rolls still cannot be said to have sufficient dewatering efficiency, and the press force, suction force, size of pores formed in the suction rolls and their arrangement are still low. Attempts have been made to make the most efficient dehydration by changing the pit etc., but if the pressing force or suction force is too large, the wet paper may be crushed or the degree of vacuum will be reduced due to the suction of air and the dehydration rate will be reduced. Decrease, and also
It is known that there is a disadvantage that a so-called shade mark is generated depending on the hole diameter of the fine holes.

[0004] That is, the problem with the conventional suction press roll is that it has a limit in improving the dewatering efficiency. Therefore, the present invention has been made in view of the above-mentioned drawbacks, the conventional,
An object of the present invention is to provide a paper machine having a suction press roll capable of obtaining more efficient dewatering efficiency by utilizing not only a mechanical dewatering function of pressing and suction but also an electric suction force.

[0005]

In order to solve the above-mentioned problems, a suction press roll is provided between a wire part and a press part in order to solve the above-mentioned problems. In the paper machine having the interposed structure, a technical means is provided in which a DC voltage is applied between the compression roll and the suction roll of the suction press roll.

[0006]

Next, the operation of the present invention will be described with reference to FIG. 2 and FIG.

First, conventionally, as shown in FIG.
Is compressed with the pressing force Pa by the compression roll P1 and the suction roll P2 together with the felt 1, and the squeezed water is provided with the pores 2 formed in the suction roll P2 and the suction box 3 described below disposed in the suction roll P2. (See FIG. 1) and the suction box 3
Is suctioned with a suction force Va by a vacuum device (not shown) connected to the pulp. At this time, since the felt 1 serves as a filter medium, the pulp in the wet paper web M is deposited on the upper surface of the felt 1 and causes the clogging of the felt 1. Become. Therefore, even if the pressing force Pa and the suction force Va are unnecessarily increased in this state, the improvement of the dewatering efficiency cannot be expected. If the pressing force Pa is too large,
The water squeezed out between the compression roll P1 and the suction roll P2 stays and disturbs the layer of the wet paper web M, adversely affecting the surface smoothness of the product, causing paper breakage, and causing a suction force Va.
If the value is too large, a shade mark will be formed on the product or the degree of vacuum will be reduced by sucking air, and the suction force Va will be reduced.

On the other hand, in the paper machine of the present invention, the third
As shown in the figure, the compression roll P1 and the suction roll P2 serve as electrodes, and the felt 1 serves as a water-permeable diaphragm interposed therebetween, and water is interposed between the compression roll P1 and the suction roll P2. And a wet paper web M containing water is interposed between the felt 1 and the compression roll P1 (in some cases, two wet paper webs M are sandwiched between the two felts 1). become. In this state, when a DC voltage is applied to the compression roll P1 and the suction roll P2 by the power supply device 4 (the compression roll P1 is an anode, and the suction roll P2 is a cathode), the pulp content in the wet paper web M which usually has a negative charge is The pulp moves toward the compression roll P1 (actually, the pulp is evenly distributed in the water so as not to accumulate on the surface of the felt 1 against the suction force of the suction roll P2). It is expected to exhibit the effect of moving to the suction roll P2 side through.

Although the above-mentioned electroosmotic action is generally widely known in the past, it has been partially applied to the dewatering of waste liquid in the paper manufacturing industry, but has been proposed for application to a paper machine. Absent. The effect of electroosmosis is that the function is recognized only after the electric field acts for a long time. When the wet paper web M passes through the electric field at a speed of several tens of meters per second to 100 meters per second or more, the effect of electroosmosis is It is a common belief that it will not work, and its application to paper machines is therefore meaningless. That is, in order to obtain this electroosmotic action in a paper machine, it is necessary to apply an extremely long-range electric field in the flow direction of the electric field area or to suppress the flow velocity to be low, in other words, to extremely reduce the passing speed of the wet paper web M. The conventional idea is that it is necessary.

[0010] The suction press roll used in the present invention is a so-called line contact portion, and even if a temporary electric field is applied, the area of the electric field is very small. The above description of the effect that the electroosmotic action can be obtained even when passing through is inconsistent with the common belief. However, if it is assumed that the electroosmotic action is obtained ignoring the above-mentioned conventional theory, the pressing force Pb and the suction force Vb shown in FIG. There is. That is, if the purpose is electroosmotic dehydration,
This eliminates the need for mechanical dehydration of press and suction.

Therefore, the present inventor has made the present invention convinced that there is a possibility that an efficient dehydration action may be obtained by combining the dehydration action by electroosmosis and the mechanical dehydration action. That is, instead of using electroosmosis as a dehydrating action, dehydration is performed only by the pressing force Pb and the suction force V.
b) mechanical dehydration by means of b), which is used as an action to improve the conditions. The true action of the present invention is to prevent pulp from accumulating on the surface of the felt as a filter medium due to electroosmosis and causing clogging. , The pressing force Pb and the suction force Vb
In other words, the limit of the improvement of the dewatering efficiency due to the increase in the pressure is exceeded.

[0012]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

In the drawing, P is a suction press roll interposed between a wire part and a press part of a paper machine. Although the wire part and the press part are not shown in the drawing, those known in the art are used. In the wire part, the pulp slurry is converted to wet paper M by a papermaking screen.
The wet paper web M is also guided by a pick-up roll (not shown) onto the felt 1 from a papermaking screen, dewatered by a press part, and further dried by a dryer part (not shown). Of course, it is the same as before.

The suction press roll P is composed of a compression roll P1 and a suction roll P2. The suction roll P2 is formed in a cylindrical shape, and has a large number of pores 2 on its peripheral surface.
., A suction box 3 is accommodated in the compression roll P1, and a specific range of pores 2, 2, 2, which is a vacuum device (not shown) connected to the suction box 3.・
.. The suction force is generated in the group as before.

One or more of the compression rolls P1 are pressed against one suction roll P2 with a constant pressing force, and the compression roll P1 and the suction roll P2 are separated from each other. It rotates in the contacting direction, and applies a predetermined compressive force to the felt 1 that is sandwiched and passed between the two and the wet paper M that overlaps the felt 1.

As the above-mentioned compression roll P1 and suction roll P2, conventionally known ones may be used. However, in the present invention, since a DC voltage is applied between the compression roll P1 and the suction roll P2 by the power supply 4, a conductive material is used. A material of a conductive material is used. In order to apply a DC voltage between the compression roll P1 and the suction roll P2, the anode output terminal of the power supply device 4 is connected to the compression roll P1.
1, the cathode output end is electrically connected to the suction roll P2.

[0017]

Since the present invention is as described above, when the wet paper web M passes through the suction press roll P, the electroosmotic action is very small and no practical effect can be obtained. The pulp content in the paper M is prevented from accumulating on one surface of the felt and the filter medium is prevented from being clogged.
It is possible to provide a paper machine capable of performing efficient dewatering without increasing the compressive force of 1 and without increasing the suction force of the suction roll P2. Specifically, when a DC voltage of 120 volts was applied to a suction press roll of a conventionally known paper machine, an improvement in dewatering efficiency of 8 to 15% was obtained.

The above-mentioned improvement of the dewatering efficiency requires electric energy for the suction press roll P, but can reduce the amount of heat consumed in the subsequent dryer part, and has a remarkable effect of reducing energy consumption as a whole. is there.

Further, a remarkable effect of the present invention is that when the dewatering efficiency is set to the same value as the conventional one, the compression force of the compression roll P1 and the suction force of the suction roll P2 can be reduced, and the reduction in strength due to the crushing of the wet paper is prevented. It is possible to provide a publicly available paper machine for making paper having a soft texture.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of the paper machine of the present invention.

FIG. 2 is a cross-sectional view illustrating the principle of dehydration of a conventional device.

FIG. 3 is a sectional view showing the principle of dehydration of the present invention.

[Explanation of symbols]

 1 felt 2 pores P suction press roll P1 compression roll P2 suction roll M wet paper

Claims (1)

(57) [Claims] 1. A paper machine having a suction press roll (P) interposed between a wire part and a press part,
A paper machine wherein a DC voltage is applied between a compression roll (P1) and a suction roll (P2) of the suction press roll (P).