JPS63111960A - Drier - Google Patents

Abstract

PURPOSE:To prevent the uneven coating in the widthwise direction of a strip and to improve the quality by forming a specified gap on the counter-aerofoil nozzle side of the strip, and providing plural sets of ion wind generators in the widthwise direction of the strip. CONSTITUTION:When hot air is blown off from an aerofoil nozzle 3 to dry the strip 1 of paper, etc., a specified gap is formed on the counter-aerofoil nozzle side of the strip 1, and plural sets of ion wind generators consisting of meshy electrode 7 and a wire or rod-shaped electrode 10 opposed to the electrode 7 are provided in the widthwise direction of the strip. As a result, the water content in the strip in each zone can be controlled, uneven drying especially in the widthwise direction can be prevented, and the quality is improved. Besides, the velocity of the ion wind can be regulated by adjusting the voltage between the electrodes, and the wind velocity is easily controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a drying device using an airfoil nozzle that can be applied to paper coater machines, paper converting machines, printing machines, etc.

(Prior Art) For example, for drying coated paper in a paper coater machine, a so-called hot air dryer, as shown in cross section in FIG. 5, has conventionally been used. The paper 1 enters the main body 4 of the drying device in the direction indicated by the arrow in the figure. 2 in the figure is a support roll, and the paper 1 that has been guided by the support roll 2 and enters the dryer main body 4 is blown out from the airfoil nozzle 3 in the direction indicated by the arrow, which is opposite to the running direction of the paper 1. dried with hot air. FIG. 6 is a three-dimensional view of the inside of the drying device. Air for hot air is sent from the outside of the main body 4 to the supply ladder 5, and is further supplied to the nozzle header through the opening shown by the broken line in the figure. 6 and then flows into the airfoil nozzle 3 as shown by the arrow, and is blown out from the slit S at the tip of the airfoil nozzle 3.

By the way, the width of paper 1 that is conventionally dried is about 2 to 5 m, but in the conventional apparatus with the above structure, the blowing speed of hot air in the width direction tends to be uneven depending on the conditions, and as a result, the width of the paper There was a drawback that moisture unevenness occurred in the direction, causing problems such as curling, which had a negative impact on quality.

(Problems to be Solved by the Invention) The present invention solves the conventional problem that the hot air blowing speed tends to be uneven (therefore, drying unevenness occurs especially in the width direction, which adversely affects paper quality). It was made for the purpose of

(Means for Solving the Problems) Therefore, the present invention provides a drying device for drying a strip by blowing hot air from an airfoil nozzle, in which a predetermined gap is provided on the opposite side of the strip from the airfoil nozzle. In addition, a plurality of sets of ion wind generators each consisting of a wire mesh electrode and a linear or rod-shaped electrode whose tips are opposite to the same electrode are arranged across the width of the same strip, and this solves the above problem. It is intended as a solution.

In other words, the present invention applies the principle of ionic wind generated by corona discharge for the purpose of uniformizing the moisture profile in the paper width direction, and divides the paper width direction into several sections and connects wire mesh electrodes and linear or A large number of sets of ion wind generators consisting of rod-shaped electrodes are installed to generate ion wind while selecting relatively moisture-rich parts of the paper, and the ion wind creates a laminar boundary layer between the paper and the hot air. The idea is to improve heat transfer by breaking the paper, and to even out the moisture distribution in the paper.

(Function) The wire or rod electrode is the (+) pole, and the wire mesh electrode is the (-) pole.
When a DC voltage is applied to both poles to cause a corona discharge, an ionic wind is generated from the (+) pole to the (-) pole.
The ion wind passes through the mesh of the wire mesh electrode and collides with the surface of the opposing strip as a jet. As a result, the laminar flow of hot air blown from the airfoil nozzle on the surface of the strip is disrupted, improving heat transfer.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings. 1st
The figure is a schematic side cross-sectional view of a drying device showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view in the width direction at an arbitrary position in FIG.

As shown in both figures, the drying device according to this embodiment has a large number of airfoil nozzles 3 arranged vertically in a staggered manner so that the airfoil nozzles that are vertically adjacent to each other do not come into contact with the running surface of the girder 1. Several units of wire mesh electrodes 7 of 20 to 40 meshes are installed in the width direction of the paper with a predetermined gap of about 100 mm, and each unit is grounded via a switch 8. Here, the dimensions of the wire mesh electrode 7 are not particularly limited, but the number of meshes should be such that air can pass through it without resistance. Further, as a counter electrode, a metal wire electrode 10 made of a thin metal wire (the material and diameter are not specified) is attached at a distance of about 10 fins from the wire mesh electrode 7, and the (+) of the DC power supply is connected via the switch 9. Wire to the pole. Note that, as the metal wire, for example, a piano wire can be used.

Both electrodes 7.10 are supported by a support made of an insulating material (not shown) from the main body of the drying device.

By the way, normally when drying paper, airfoil nozzle 3
The wind speed at the exit of the paper is 50 to 60 m/s, but the flow pattern is thought to be approximately as shown in Figure 4, and the speed is predicted to be several m/s especially near the surface of the paper. It is thought that heat transfer is reduced due to the generation of a laminar boundary layer. As a result, as the wind speed becomes uneven, moisture unevenness becomes more noticeable, and drying becomes more likely to occur.

Under such circumstances, the metal wire electrode 10 and the wire mesh electrode 7
Specifically, when a DC voltage of about 15 to 20 KV is applied during this period, an ionic wind of several m/s is generated from the metal wire electrode 10 to the wire mesh electrode 7, as shown in Figure 3. The ionic wind passes through the wire mesh and impinges on the paper, creating local turbulence that improves heat transfer. Here, several units installed in the width direction are controlled by switches 8 and 9, respectively, to selectively generate ion wind in each zone, thereby making it possible to control moisture content. The number of electrodes in the width direction is 5 to 10.
The number is not particularly limited.

(Effects of the Invention) As described above in detail, according to the present invention, by installing several units of ion wind generating electrodes in the width direction, it is possible to control the moisture in the strip in each zone, and uneven drying can be prevented. This will lead to improved quality. Furthermore, the speed of the ion wind can be adjusted by adjusting the voltage between the electrodes, making it easy to control the wind speed.

[Brief explanation of the drawing]

Fig. 1 is a side cross-sectional view of an airfoil dryer showing an embodiment of the present invention, Fig. 2 is a cross-sectional view in the width direction at an arbitrary position in Fig. 1, and Fig. 3 is a flow of air when the present invention is implemented. 4 is a schematic diagram showing the air flow of a conventional airfoil dryer, FIG. 5 is a side sectional view of a conventional airfoil dryer, and FIG. 6 is a schematic diagram showing the inside of the airfoil dryer. It is a three-dimensional diagram. Explanation of the main parts of the diagram l--(coated) paper 3--airfoil nozzle 7-wire mesh electrode 10--metal wire electrode

Claims (1)

[Claims] In a drying device for drying a strip by blowing hot air from an airfoil nozzle, a wire mesh electrode and a wire or rod-shaped electrode facing the same electrode with a predetermined gap on the side opposite to the airfoil nozzle of the strip A drying device characterized in that a plurality of sets of ion wind generators consisting of the following are arranged across the width direction of the same strip-shaped object.