JPH0336957B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is a porous wet web, for example, a method for removing liquid components such as water impregnated into a thin fibrous web such as thin printing paper during the manufacturing process of the web. The present invention relates to a device for removing liquid from a web.

[Prior Art] FIG. 9 is a schematic diagram showing a part of a conventional paper making line. The web 1 formed through the head box and wet part is dehydrated in a press part 2 and a drying part 3, and then finished in a calender part 4 to become a product. In the drying part 3, the web 1 is brought into contact with a cylindrical dryer cell 5 heated by blowing steam,
The web temperature is gradually increased to evaporate and remove moisture. The web moisture content at the entrance of the drying part 3 is 50% to 60%, and the web moisture content at the exit of the drying part 3 for turning the web 1 into products is 7%. Therefore, the number of dryer cells 5 required to reduce the moisture content of the web 1 from 50% to 60% to 7% varies depending on the speed and thickness of the web 1, but is generally 50 to 70. , line length 3L of drying part 3 is also 50
~70m is required.

As a technology that is considered useful for shortening the line length in the conventional drying part 3, there is a water removal device according to USP 4,324,613. This moisture removal device allows a web conveyed in felt to pass through a nip area between a pair of heating rollers and an air permeable roller. The heated rollers of the moisture removal device deliver heat under high contact pressure to the web as it passes through the nip area, rapidly converting the moisture in the web to steam that penetrates the web and remains in the web. This results in the free water being carried out to the felt side. Therefore, it seems that this moisture removal device has good moisture removal efficiency and can shorten the line length of the drying part 3 described above.

[Problem to be solved by the invention] However, according to the inventor's considerations, the above
In the moisture removal device of USP4324613, the heat source of the heating roller is hot gas blown onto the surface of the heating roller, or electrical resistance heat from a hot wire embedded in the surface, and the entire surface of the heating roller is constantly heated. There are difficulties in maintaining uniform high temperatures. This makes it difficult to thoroughly and intensely heat the web passing through the nip area formed by the heating roller, and the moisture in the web is extremely rapidly (explosively) converted to steam at the interface with the heating roller. This means that it is difficult to reduce the amount of free water, and the amount of free water carried out by steam cannot be expected to be very large.

The present invention maintains the entire surface of the heating roller at a constant and uniform high temperature, heats the web thoroughly and intensely as it passes through the nip area formed by the heating roller, and heats the web at the boundary with the heating roller. The purpose of this invention is to convert the liquid content of the web into vapor extremely rapidly (explosively), to enable the vapor to carry out and remove a large amount of free liquid in the web, and to reliably improve the liquid removal efficiency.

[Means for Solving the Problems] The present invention according to claim 1 provides a transfer belt that is provided with a porous support surface and that supports and transfers the web on the support surface, and a transfer belt that supports the web on the support surface. A heating roller rotates in thermal contact with the web being held, and a nip area is provided between the heating roller and the heating roller, which is in pressure contact with the back side of the carrying surface that supports the web, and pinches the transport belt and the web. The heating roller sends heat under high contact pressure to the web passing through the nip region, rapidly converting the liquid content in the web into vapor, and this vapor causes the web to In an apparatus for removing liquid from a web, the heating roller is configured to pass through the web and carry out any free liquid remaining in the web to the side of the porous bearing surface of the transfer belt. The roller body is provided with a magnetic flux generating section that generates magnetic flux for induction heating, and is also provided with an airtight chamber in which a heating medium is sealed in a vacuum state within the thickness of the peripheral wall of the roller body.

According to a second aspect of the present invention, a web preheating device for preheating the entire web from both the front and back sides of the web is disposed upstream of the web line with respect to the nip area formed by the heating roller and the pressure contact device.

[Function] According to the present invention as set forth in claim 1, the heating roller induces a current by the alternating magnetic flux generated by the magnetic flux generating portion to generate heat in the peripheral wall portion of the roller body, and
The airtight chamber acts like a heat pipe to make the temperature of the peripheral wall portion of the roller body uniform, and as a result, the surface temperature is constantly maintained at a uniform high temperature state.

Therefore, even when a web with varying heat loads enters the web, the heating roller comes into close contact with the web with high contact pressure in the nip area formed together with the pressure welding device, and lifts the web from the heating roller. Always heat thoroughly and intensely. This causes the liquid content in the web to be very rapidly (explosively) converted to vapor at the interface with the heated rollers, which vapor transfers the free liquid in the web onto the porous support surface of the transfer belt. A large amount will be transported.

Therefore, according to the present invention as set forth in claim 1, the liquid removal efficiency becomes extremely good, and the desired water removal work can be achieved with a small equipment space.

According to the second aspect of the present invention, the web whose entire surface including the front and back sides has been preheated by the web preheating device is introduced into the nip region between the heating roller and the pressing device. Therefore, the preheating device can preheat the liquid in the web until just before evaporation, and the thermal energy of the heating roller can be used more effectively for rapid and explosive vapor conversion. The device can raise the temperature of the liquid in the web to lower its viscosity (resistance to liquid removal), and the resistance to liquid discharge due to vapor generated by the heating roller can be reduced in advance. That is,
This effectively complements the liquid removal function of the present invention as set forth in claim 1 above.

[Example] Fig. 1 is a schematic diagram showing a moisture removing device according to an embodiment of the present invention, Fig. 2 is a schematic diagram showing an enlarged main part of the moisture removing device, and Fig. 3 is a heating roller. A schematic diagram, FIG. 4 is a schematic diagram showing an example of applying the present invention to a paper making line, FIG. 5 is a schematic diagram showing another example of applying the present invention to a paper making line, and FIG. 6 is a schematic diagram showing an example of applying the present invention to a paper making line. It is a line diagram showing an effect.

As shown in FIG. 1, the moisture removal device 10 includes a transfer belt 11, a heating roller 12, and a pressure roller 13.
(pressure contact device), and the transfer roller 14
The water content of the web 1 guided and conveyed is removed.

The transfer belt 11 is made of a perforated steel belt, a glass fiber belt, a carbon fiber belt, etc., and has a porous support surface 11A, and supports and transfers the web 1 on this support surface 11A. (See Figure 2). The transfer belt 11 is wound around a support roller 16 provided on a machine base 15 in a circumferential manner. The transfer belt 11 has a function of absorbing moisture in the web, a function of smoothing the surface of the web, and a function of withstanding tension.

The heating roller 12 rotates in thermal contact with the web 1 supported by the transfer belt 11. here,
The heating roller 12 of this embodiment is constructed as shown in FIG. 3, with a roller main body 18 supported by a bearing 17 provided on a machine base 15, and the roller main body 18 is rotatable by a drive motor (not shown). The roller body 18 has a fixed shaft 2 therein via a bearing 19.
0 in a stationary state, and has a built-in magnetic flux generating section 23 constituted by an iron core 21 formed by a part of a fixed shaft 20 and an induction coil 22 wound around the iron core 21. The magnetic flux generating section 23 generates magnetic flux for inductively heating the roller body 18. The heating roller 12 also has an airtight chamber 18A within the thickness of the peripheral wall of the roller body 18, in which a heat medium (water, oil, etc.) is sealed in a vacuum state.

The pressure roller 13 presses the web 1 of the transfer belt 11.
A nip region N1 is formed which is in pressure contact with the back surface of the supporting surface 11A that supports the web 1, and which pinches the transfer belt 11 and the web 1 between it and the heating roller 12. Here, in the moisture removal device 10 of this embodiment, a pair of support stands 24 are provided on both sides of the lower part of the heating roller 12 on the machine stand 15, and each pressure roller 13 is rotatable on a bearing 25 provided on each support stand 24. By supporting the heating roller 12, the two pressure rollers 13 are respectively installed at two positions along the outer periphery of the heating roller 12. Each pressure roller 13 also has an adjustment screw 26 that can adjust the position of the bearing 25 with respect to the support base 24.
(nip position adjustment device)
Thereby, the distance between the nip regions N1 formed by the pressure rollers 13 can be adjusted. Note that the support stand 24 of each pressure roller 13
A pressure adjustment cylinder 27 (nip pressure adjustment device) is interposed between the press roller 13 and the machine base 15.
The nip pressure between the roller and the heating roller 12 can be adjusted as appropriate.

Furthermore, in the moisture removal device 10, a web preheating device 28 is provided on the upstream side of the web line with respect to the nip region N1 formed by the heating roller 12 and the pressure roller 13, for preheating the entire web 1 from both the front and back surfaces of the web 1. It is placed. Web preheating device 2
8 consists of a microwave, far/near infrared heater, etc. As shown in FIG. 1, the upper and lower heaters 29
It is constructed by supporting A and 29B on the machine stand 15 in an openable and closable state. 30 is a heater opening/closing cylinder.

Therefore, the moisture removing device 10 is installed in the fourth drying part 3 of the paper making line, for example.
As shown in the figure, it is used by installing one set of heating rollers 12 and pressure rollers 13, and one web preheating device 28. This usage mode is the fifth
As shown in the figure, in addition to one web preheating device 28, two sets of heating rollers 12 and pressure rollers 13 are installed, or the web preheating device 28 is not used and one or more sets of heating rollers 12 and pressure rollers 13 are installed. It can be modified in various ways such as installation.

Next, the operation of the above embodiment will be explained.

According to the above-mentioned embodiment, the heating roller 12 generates heat in the peripheral wall of the roller body 18 due to the electric current being induced by the alternating magnetic flux generated by the magnetic flux generating section 23 by applying an alternating current voltage to the induction coil 22. The airtight chamber 18A acts like a heat pipe to make the temperature of the peripheral wall of the roller body 18 uniform, and as a result, the surface temperature is constantly maintained at a uniform high temperature state.

Therefore, even when the web 1 with varying heat loads enters, the heating roller 12 applies a high contact pressure to the web 1 in the nip area N1 formed with the pressure roller 13, as shown in FIG. The web 1 is always thoroughly and intensely heated without being lifted from the heating roller 12. As a result, the moisture in the web is very rapidly (explosively) converted into evaporation at the interface with the heating roller 12, and this steam transfers the free water in the web onto the porous support surface 11A of the transfer belt 11. A large amount will be transported to the side. Note that, as described above, the steam generated at the boundary with the heating roller 12 is dissipated into the atmosphere at the exit side of the heating roller 12 where the web 1 is released from the nip region N1. In FIG. 2, W is water, F is fiber, A is air, and V is vaporized water.

Therefore, according to the above embodiment, the water removal efficiency is extremely good, and the desired water removal work can be achieved with a small equipment space.

Further, according to the above embodiment, two pressure rollers 13 are used for one heating roller 12.
At the same time, the transfer belt 11 stretched between both pressure rollers 13 also pinches the web 1 between it and the heating roller 12 based on the tension of the transfer belt 11, thereby forming the above-mentioned nip region N1.
A quasi-nip region N2 is formed which performs substantially the same moisture removal function as in the above. Therefore, the water removal effect due to evaporation of water in the web by the thermal energy of the single heating roller 12 and the removal of free water in the web by the steam is carried out in the plurality of nip regions N1 and the quasi-nip region N2. As a result, the amount of water removed per heating roller 12 becomes large, and the water removal efficiency can be improved.

Furthermore, the distance between the nip regions N1 formed by the pressure rollers 13 can be adjusted by the adjustment screw 26 as a nip position adjustment device.
Therefore, it is possible to adjust the timing of the water removal action exerted on the web 1 by each nip region N1 and the length (time) of the quasi-nip region N2, and the length (time) of the nip region N1 and quasi-nip region formed around the heating roller 12 can be adjusted. The water removal state can be easily adjusted by adjusting the pressure state of N2, and the workability of water removal can be improved.

In the moisture removing device 10, the heating roller 12 has a built-in heating source and no heating source is attached around it, so two or more pressure rollers 13 are installed in a wide area around the heating roller 12. can be easily installed.

In addition, in the above embodiment, the web 1, which has been entirely preheated including the front and back sides, is heated by the web preheating device 28, and is heated between the heating roller 12 and each pressure roller 1.
It will be introduced into the nip area N1 of No. 3. Therefore, the preheating device 28 can preheat the moisture in the web until just before evaporation, and the thermal energy of the heating roller 12 can be used more effectively for rapid and explosive steam conversion.
Furthermore, the preheating device 28 can raise the temperature of the moisture in the web to lower its viscosity (dehydration resistance), and the resistance to moisture removal due to steam generated by the heating roller 12 can be reduced in advance. That is, this effectively complements the water removal effect of the present invention described above.

According to the experimental results on the paper making line shown in Fig. 4, when the web conveyance speed is 150 m/min,
The relationship between the inlet web moisture Win and the outlet web moisture Wout of the moisture removal device 10 was as shown in FIG. In other words, the moisture content of the inlet web is 51%, while the moisture content of the outlet web is 24%.
It could be shortened to m. In other words, it was confirmed that the number of conventional dryer cells could be reduced by 50 to 30%, and the equipment space could be reduced by 40 to 20% compared to conventional methods.

Further, in the paper making line shown in Fig. 5, the total length 3L of the drying part 3 could be shortened to 10 to 15 m. In addition, in Figures 4 and 5, 10L
is the total length of the moisture removal device 10.

FIG. 7 is a schematic diagram showing another embodiment of the present invention. In FIG. 7, numeral 12 is a heating roller having the same structure as in the embodiment shown in FIG. This embodiment differs from the embodiment shown in FIG. 1 in that an independent transfer belt 100 is provided for each pressure roller 13. 16 is a support roller. Note that the transfer belt 100 may have three functions: a function of absorbing moisture in the web, a function of smoothing the web surface, and a function of withstanding tension.
The belt 100A may have the above functions, and the belt 100B may have the above functions.

FIG. 8 is a schematic diagram showing another embodiment of the present invention. In FIG. 8, numeral 12 is a heating roller having the same structure as in the embodiment shown in FIG. 1, and 13 is also a pressure roller, which is the same as in the embodiment. This embodiment is different from the embodiment shown in FIG.
This is because only the pressure welding device (pressure welding device) is arranged in a corresponding manner.
200 is a transfer belt, and 16 is a support roller.
Note that the transfer belt 200 may be provided with the three functions described above with only one belt, but it may be separated into two belts 200A and 200B, and the belt 200A has the above functions, and the belt 200B has the functions described above. The above functions may also be provided.

Further, the pressing device of the present invention may be in the form of a fixed shoe instead of in the form of a roller.

[Effects of the Invention] According to the present invention, the entire surface of the heating roller is constantly maintained at a uniform high temperature state, and the web passing through the nip area formed by the heating roller is thoroughly and intensely heated. The liquid content in the web is extremely rapidly (explosively) converted into vapor at the boundary with the rollers, and this vapor allows a large amount of free liquid in the web to be carried away and removed, ensuring improved liquid removal efficiency. be able to.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a moisture removal device according to an embodiment of the present invention, FIG. 2 is a schematic diagram showing an enlarged main part of the moisture removal device, and FIG. 3 is a schematic diagram showing a heating roller. Figure 4 is a schematic diagram showing an example of applying the present invention to a paper making line, Figure 5 is a schematic diagram showing another example of applying the present invention to a paper making line, and Figure 6 is a line showing the water removal effect of the present invention. FIG. 7 is a schematic diagram showing another embodiment of the present invention, FIG. 8 is a schematic diagram showing another embodiment of the present invention, and FIG. 9 is a schematic diagram showing a conventional paper making line. 1... Web, 10... Moisture removal device, 11...
...Transfer belt, 11A...Supporting surface, 12...Heating roller, 13...Press roller, 18...Roller body, 18A...Airtight chamber, 23...Magnetic flux generating section, 2
8... Web preheating device.

Claims (1)

[Claims] 1. A transfer belt that is provided with a porous support surface and that supports and transfers the web on the support surface, and that rotates in thermal contact with the web supported by the transfer belt. It has a heating roller and a pressing device that presses against the back side of the supporting surface that supports the web of the transfer belt, and forms a nip area between the heating roller and the holding surface that holds the transfer belt and the web, and The rollers deliver heat under high contact pressure to the web as it passes through the nip area, rapidly converting the liquid in the web to vapor that penetrates the web and removes any remaining free liquid in the web. In a web liquid removal device configured to be delivered to the porous supporting surface side of a transfer belt, a heating roller generates magnetic flux within the roller body for induction heating of the roller body. What is claimed is: 1. A device for removing liquid from a web, comprising: an airtight chamber in which a heating medium is sealed in a vacuum state within the thickness of a peripheral wall of a roller body; 2. The apparatus for removing liquid from a web according to claim 1, further comprising a web preheating device for preheating the entire web from both the front and back sides of the web, located upstream of the web line with respect to the nip area formed by the heating roller and the pressure contact device.