JP2006002312A - Method for controlling moisture profile of paper web and moisture profile controlling device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling the moisture profile of paper web so that the moisture profile of paper web may be controlled more uniformly and provide a moisture profile controlling device using the controlling method. <P>SOLUTION: In the method for controlling moisture profile of paper web 2 according to this invention, moisture is fed through canvas 4 to the paper web 2 by allowing the paper web 2 to wrap around the drier cylinder 3, and pressing the canvas 4 from the outer peripheral face toward the paper web 2 and feeding water to the outer surface of the canvas 4. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a moisture profile control method for a paper web in a dryer of a paper machine and a moisture profile control device using the method.

Conventionally, a dryer used in a drying process of a paper machine has a plurality of cylindrical dryer cylinders that are heated by being filled with steam. The paper web sent from a previous process such as a press process is used as a dryer. It is configured such that the moisture of the paper web can be evaporated and dried by passing it while sequentially pressing against the cylindrical surface of the dryer cylinder.
The moisture content of the paper web after being dried by such a dryer is adjusted to around 6%, but the moisture profile, which is the moisture content distribution in the width direction, has a variation of about 1 to 5%. was there. Causes of this include fluctuations in weighing during the papermaking process, variations in dewatering in the pressing process, variations in the heat distribution on the surface of the dryer cylinder, and the like. Variations in the moisture profile of the dried paper web can cause many problems, such as uneven quality as a paper product, miswinding and paper breaks during winding.

  Therefore, the amount of coating liquid is controlled in the width direction during coating in the previous process before entering the dryer, or water is supplied directly by spraying mist-like moisture onto the paper web before coating. By adjusting the moisture profile of the paper web (see, for example, Patent Document 1), a plurality of induction heating coils are arranged in the width direction with respect to the dryer cylinder installed in the middle or outlet of the dryer. Heating while controlling the surface of the dryer cylinder and adjusting the moisture profile of the paper web by controlling the amount of heat for drying in the width direction (for example, see Patent Document 2).

Japanese Patent Laid-Open No. 5-209395 (2nd page) Japanese Patent Publication No. 8-26519 (2nd page)

However, when the moisture profile is adjusted by supplying moisture or the like as in Patent Document 1, the moisture supply amount for the paper web is excessive even if the moisture is made into a mist, and the moisture content of the paper web is 30 to 30%. Adjustment was possible only with a paper web having a high moisture content in the stage before entering the dryer, such as 40%. As a result, the moisture content when the moisture profile is adjusted and the moisture content at the outlet of the dryer are greatly different, and it may be difficult to uniformly control the moisture profile of the paper web.
Further, as in Patent Document 2, when the moisture content distribution is adjusted by heat drying at the middle or outlet of the dryer, the moisture content can be adjusted close to the moisture content at the dryer outlet, but the entire paper web becomes overdried. There was a risk that the quality of the product would be reduced.
The present invention has been made in view of such circumstances, and a moisture profile control method for a paper web, which makes it possible to more uniformly control the moisture profile of the paper web in a drying process by a paper machine dryer. An object is to provide a moisture profile control device used.

  The first aspect of the present invention for achieving the above object is to dry a paper web by winding it around a plurality of heated cylindrical cylinders and then pressing a belt-like canvas made of water-absorbing fibers on its outer peripheral surface. A method for controlling the moisture profile of a paper web used in a dryer of a paper machine, wherein the moisture profile of the paper web is grasped and a moisture deficient portion in the width direction of the paper web is identified based on the grasped moisture profile Then, the paper web is wound around the dryer cylinder and moisture is supplied to the outer peripheral surface of the canvas in a state where the canvas is pressed from the outer peripheral surface, and the paper web is passed through the canvas to which the water has been supplied. Supplying moisture to the moisture-deficient portion of the paper and controlling the moisture profile of the paper web to be constant. It is set to.

  According to the first aspect, when moisture is supplied to the outer peripheral surface of the canvas, the moisture is absorbed by the canvas. Thereafter, the water absorbed by the canvas reaches the paper web, whereby the water is supplied to the paper web. At this time, excess water out of the supplied water is absorbed by the canvas, so that it is possible to prevent the water supply to the paper web from becoming excessive. Therefore, even when the variation width of the moisture profile of the paper web is not large, an appropriate amount of moisture can be supplied to the moisture-deficient portion of the paper web. In addition, since moisture is once absorbed by the canvas, for example, moisture does not become scattered by forming water droplets on the paper web surface, and moisture is appropriately dispersed in the moisture-deficient portion. Can be supplied in a uniform state.

  A second invention for achieving the above object is to wind a paper web by winding it around a plurality of heated cylindrical dryer cylinders and pressing a belt-like canvas made of water-absorbing fibers on its outer peripheral surface. A moisture profile control device for a paper web used in a dryer of a paper machine, comprising: moisture profile grasping means for grasping a moisture profile of the paper web; and the paper web is wound around the dryer cylinder and Moisture supply means for supplying moisture to the outer peripheral surface of the canvas in a pressed state, supplying moisture to the paper web through the canvas supplied with moisture, and the paper based on the grasped moisture profile Moisture shortage in the width direction of the paper web to keep the web moisture profile constant Identify min, it is characterized in that the moisture profile is provided with a control means for controlling the water supply means to the water supply so as to be constant.

  According to the moisture profile control device according to the second invention, moisture can be supplied to the paper web by using the method according to the first invention. Therefore, when the variation width of the moisture profile of the paper web is not large. Even in such a case, an appropriate amount of moisture can be supplied to the moisture-deficient portion of the paper web.

  In addition, according to the present invention, since the amount of water supplied to the paper web can be made very small, the paper web in a state where the drying has progressed and is almost completed, that is, the moisture content is in the range of 3 to 12%. Moisture can be supplied to a certain paper web. In this case, the control can be performed more uniformly and accurately by adjusting the moisture profile of the paper web in the almost dried state.

  As described above, according to the moisture profile control method and moisture profile control apparatus for a paper web according to the present invention, moisture is supplied to the paper web through the canvas, so that the variation width of the moisture profile of the paper web is large. Even if not, an appropriate amount of moisture can be supplied, and the moisture profile of the paper web can be more uniformly controlled.

  Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a side view showing an outline of a dryer provided with a moisture profile control device to which a moisture profile control method according to an embodiment of the present invention is applied.

  A dryer 1 in the figure is an apparatus for drying a paper web 2 used in a drying process of a paper machine and sent from a press process or a size press disposed in the drying process. In such a dryer 1, the paper web 2 sent from the previous process along the arrow A in the figure enters the dryer 1 from the inlet portion S, and the paper web 2 dried in the dryer 1 is passed through the outlet portion in the figure. E is sent to the next process. The dryer 1 includes a plurality of dryer cylinders 3, a canvas 4 for pressing the paper web 2 against the surface of the dryer cylinder 3, a plurality of canvas rolls 5 constituting the path of the canvas, and a moisture profile control device. The moisture supply device 6 and the moisture profile measuring device 7 for measuring the moisture profile which is the moisture content distribution in the band width direction of the paper web 2 are provided.

  The dryer cylinder 3 (hereinafter also referred to as the cylinder 3) is formed into a cylindrical shape using cast steel or the like, and the surface is heated by supplying steam therein. The cylinders 3 are arranged in two upper and lower stages along the cylindrical axis direction parallel to the width direction of the paper web 2 and along the traveling direction of the paper web 2. The paper web 2 is alternately wound up and down on the cylinder 3. The surface of the cylinder 3 is heated while the cylinder 3 is rotated at a predetermined rotational speed and the paper web 2 is fed toward the outlet E. The paper web 2 is configured to be dried by being brought into contact with.

  The canvas 4 is formed in an endless belt shape using water-absorbing fibers such as cotton and synthetic fiber, and the belt width is set to be approximately the same as the dimension of the cylinder 3 in the longitudinal direction of the cylinder surface. The canvas 4 is pressed against the portion of the cylinder 3 on which the paper web 2 is wound. The canvas 4 holds the paper web 2 in close contact with the surface of the dryer cylinder 3, and the canvas 4 itself absorbs moisture. And can be dried uniformly and efficiently. Further, the canvas 4 is stretched around a circular orbit by a plurality of canvas rolls 5 formed so as to press the canvas 4 against the surface of the cylinder 3 as described above, and is synchronized with the rotational speed of the cylinder 3. It is controlled to go around its orbit. A dryer (not shown) or the like for drying the absorbed moisture or the like is disposed on the portion where the canvas 4 does not come into contact with the paper web 2 on the orbit, and the canvas 4 is dried by the dryer. After that, it comes into contact with the paper web 2 again.

In FIG. 1, the moisture profile control device according to the present embodiment includes a moisture supply device 6 serving as a moisture supply unit disposed in the lower portion of the cylinder 3 near the outlet E, and a paper web 2 fed from the outlet E. A moisture profile measuring device 7 serving as a moisture profile grasping means disposed immediately after the outlet E is provided, and a control unit 8 serving as a control means.
The moisture supply device 6 is disposed at the lower part of the lower cylinder 3 closest to the outlet E so that the longitudinal direction is parallel to the band width direction of the paper web 2 and at a predetermined interval from the cylinder 3. ing. Then, water is supplied to the paper web 2 by appropriately spraying mist-like water onto the cylinder 3 around which the paper web 2 is wound. FIG. 2 is a perspective view showing the appearance of the moisture supply device 6. The moisture supply device 6 includes a rod-shaped spray header 6a and a large number of spray nozzles 6b arranged on the side surface of the spray header 6a in a line along the longitudinal direction.

  The large number of spray nozzles 6b sprays water supplied to the spray header 6a in a mist form by applying a predetermined water pressure from a water tank 9 with a pump or the like, for example, and the spray directions of all the spray nozzles 6b are mutually connected. It is attached so as to face the direction perpendicular to the longitudinal direction of the spray header 6a in parallel. And the discharge | emission capability etc. of the water at the time of spraying use these substantially the same so that it may become substantially the same in each spray nozzle 6b. The spray header 6a is set to be approximately the same as the size of the cylinder 3 in the longitudinal direction of the cylinder 3, and when water is sprayed from all the spray nozzles 6b, substantially the entire length of the cylinder 3 in the longitudinal direction of the cylinder, that is, a paper web. Thus, moisture can be supplied evenly over substantially the entire width direction. Referring also to FIG. 1, the spray header 6a is provided with an electromagnetic valve 6c capable of intermittently supplying water to each spray nozzle 6b. In FIG. 1, a pair of spray nozzles 6b and solenoid valves 6c are shown. However, the solenoid valves 6c have the same configuration, and each of a number of spray nozzles 6b arranged equally along the longitudinal direction of the spray header 6a. Correspondingly attached. And it is comprised so that it can control separately whether each spray nozzle 6b sprays a water | moisture content, respectively. In other words, by controlling the opening and closing of the electromagnetic valves 6c corresponding to the individual spray nozzles 6b, it is possible to partially spray only selected portions of the paper web 2 in the band width direction.

  The moisture profile measuring device 7 is a device for measuring the moisture profile of the paper web 2 and transmits β rays and infrared rays to the measurement portion of the paper web 2 to weigh the measurement portion (weight per unit area). And a BM meter (Basis Weight and Moisture Sensor) 7a configured to be able to simultaneously measure the amount of moisture per unit area. That is, according to the BM meter 7a, the moisture content per unit area of the paper web 2 can be calculated from these values. The BM meter 7a is configured to scan the paper web 2 in the band width direction. Since the measurement of the moisture content by the BM meter 7a is performed in a very narrow range irradiated with β rays and the like, the moisture content of the paper web 2 while scanning the BM meter 7 itself in the band width direction of the paper web 2 This moisture profile measuring device 7 can measure the moisture profile of the paper web 2.

  The control unit 8 is for controlling the moisture profile measuring device 7 and the moisture supply device 6 and uses, for example, a microcomputer. A moisture profile measuring device 7 and a moisture supply device 6 are connected to the control unit 8, and based on the moisture profile measurement data sent from the moisture profile measuring device 7, the width direction of the paper web 2 is measured. The moisture supply device 6 is controlled so that the moisture-deficient portion is specified and the moisture profile of the paper web 2 becomes constant.

The moisture profile control device provided in the dryer 1 configured as described above uniformly controls the moisture profile of the paper web 2 by the moisture profile control method described below.
That is, the moisture profile of the paper web 2 is grasped by the moisture profile measuring device 7, the moisture deficient portion in the width direction of the paper web 2 is specified based on the grasped moisture profile, and the moisture supply device 6 of the paper web 2 is identified. Moisture is supplied to the moisture-deficient part, and the moisture profile of the paper web 2 is controlled to be constant.

Here, the water supply of the water supply device 6 to the paper web 2 will be described in detail below. FIG. 3 is a side view schematically showing the arrangement relationship among the water supply device 6, the cylinder 3, the canvas 4, and the paper web 2. In the drawing, the thickness of the canvas 4 and the paper web 2 is exaggerated for easy understanding of these relationships.
In the figure, a paper web 2 is wound around the cylindrical surface of the cylinder 3. Further, the canvas 4 is pressed against the cylinder 3 on the surface of the paper web 2 which is the outer peripheral surface thereof. As described above, the water supply device 6 is disposed at a predetermined interval below the cylinder 3, and the spray nozzle 6 b is directed toward the cylinder 3.

  At this time, when sprayed water is sprayed from the spray nozzle 6 b of the water supply device 6 to supply water to the paper web 2, the sprayed water is absorbed by the canvas 4. Thereafter, when the moisture absorbed by the canvas 4 reaches the paper web 2, the moisture is supplied to the paper web 2. That is, the moisture supplied to the paper web 2 is indirectly supplied via the canvas 4. At this time, excess water out of the water supplied from the water supply device 6 is absorbed by the canvas 4, so that it is possible to prevent the water supply from becoming excessive. Accordingly, even when the variation width of the moisture profile of the paper web is not large, an appropriate amount of moisture can be supplied to the moisture-deficient portion of the paper web 2. In addition, since the supplied water is once absorbed by the canvas 4, for example, the water does not become scattered by forming water droplets or the like on the surface of the paper web 2, and can be uniformly supplied in an appropriately dispersed state.

  As described above, the water supply to the paper web 2 in the water profile control method according to the present embodiment is performed when the paper web 2 is wound around the cylinder 3 and the canvas 4 is pressed from the outer peripheral surface thereof. By supplying moisture to the outer peripheral surface of 4, an appropriate amount of moisture can be supplied to the paper web 2 through the canvas 4. Therefore, the moisture profile of the paper web 2 can be more uniformly controlled in the drying process by the dryer 1.

  Moreover, the paper web 2 wound around the cylinder 3 near the outlet E of the dryer 1 in which the moisture supply device 6 is installed is in a state where the drying by the dryer 1 is almost completed, and the moisture content is 5 to 5. It is in the range of 10%. When mist-like moisture is directly supplied to the paper web 2 in such a state, moisture is excessively supplied, and the moisture profile cannot be made uniform.

In the present embodiment, the amount of water supplied to the paper web 2 can be adjusted to an appropriate amount via the canvas 4, so that the moisture profile of the paper web 2 in a substantially dry state can be adjusted, and the control thereof is more uniform and accurate. It can be carried out.
Furthermore, since the moisture profile of the paper web 2 is uniformly adjusted when the drying process is almost completed, almost no factors affecting the moisture profile of the paper web 2 can be eliminated before being sent to the next process. The paper web 2 in a state where the moisture profile is uniformly adjusted can be sent to the next process.

  Further, since the moisture profile control apparatus according to the present embodiment can control the moisture profile of the paper web 2 by the moisture profile control method as described above, the moisture profile of the paper web 2 in the drying process by the dryer 1 is more uniformly controlled. can do.

  In addition, according to the moisture profile control method and the moisture profile control apparatus using the same according to the present invention, the moisture supplied to the paper web 2 can be adjusted to an appropriate amount by supplying moisture through the canvas 4. It is not necessary to precisely control the amount of water when supplying water. Therefore, an existing moisture supply device or the like can be used, and it can be carried out at a low cost. Further, in the present invention, the moisture profile is more uniformly controlled by supplying moisture, and the running cost such as electric power is compared with the moisture profile control method by the drying means using the induction coil as in the conventional example. Can be reduced.

  The moisture profile control method of the present invention and the moisture profile control apparatus using the moisture profile control method are not limited to the above embodiment, and the configuration and arrangement position of the moisture profile measuring apparatus and the moisture supply apparatus are the same as those of the present invention. It can change suitably based on the meaning.

It is a side view which shows the outline of the dryer used for the drying process of the paper machine provided with the moisture profile control apparatus which concerns on one Embodiment of this invention. It is a perspective view which shows the external appearance of a moisture supply apparatus. It is the side view which showed typically the relationship of arrangement | positioning of a moisture supply apparatus, the said cylinder, a canvas, and a paper web.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dryer 2 Paper web 3 Dryer cylinder 4 Canvas 6 Moisture supply device 7 Moisture profile measuring device 8 Control part

Claims (4)

Moisture profile control of paper webs used in paper machine dryers that wind paper webs by wrapping them around heated cylindrical dryer cylinders and pressing a belt-like canvas made of water-absorbing fibers on the outer circumference A method,
Grasping the moisture profile of the paper web, identifying a moisture deficient portion in the width direction of the paper web based on the grasped moisture profile, the paper web is wound around the dryer cylinder and Moisture is supplied to the outer peripheral surface of the canvas in a state where the canvas is pressed, and moisture is supplied to the moisture-deficient portion of the paper web through the canvas supplied with moisture, so that the moisture profile of the paper web is constant. A method for controlling the moisture profile of a paper web, characterized in that:   2. The moisture profile control method for a paper web according to claim 1, wherein the moisture content of the paper web when the moisture is supplied is in the range of 3 to 12%. Moisture profile control of paper webs used in paper machine dryers, which are wound around a plurality of heated cylindrical dryer cylinders and then dried by pressing a belt-like canvas made of water-absorbing fibers on the outer peripheral surface of the cylinders. A device,
Moisture profile grasping means for grasping the moisture profile of the paper web;
Moisture is supplied to the outer peripheral surface of the canvas in a state where the paper web is wound around the dryer cylinder and the canvas is pressed from the outer peripheral surface, and moisture is supplied to the paper web through the canvas to which the water is supplied. Water supply means for supplying;
Based on the grasped moisture profile, a moisture deficient portion in the width direction of the paper web for making the moisture profile of the paper web constant is specified, and the moisture is supplied so that the moisture profile becomes constant. A paper web moisture profile control device comprising: a control means for controlling the supply means.   4. The paper web moisture profile control device according to claim 3, wherein the moisture supply means supplies moisture to the paper web having a moisture content in a range of 3 to 12%.

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