JP2003328288A - Paper machine dryer and method of temperature control therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paper machine dryer for drying web, and to provide a method for the temperature control of the dryer comprising making a control of the surface temperature of the dryer rolls based on the surface temperature of the dryer rolls and the water content of the web so as to more surely prevent the web from sticking on the dryer surface. <P>SOLUTION: The paper machine dryer includes the plurality of dryer rolls 5 and performs drying the web 7 by pressing it on the dryer rolls 5 while successively wrapping it on the dryer rolls 5. The surface temperature of the dryer rolls 5 is controlled by a control means 12 based on the water content of the web 7 detected or estimated by a relevant means 9 and information (surface temperature) detected by a dryer roll surface temperature detecting means 8. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper machine dryer for drying a web, and more particularly to a paper machine dryer suitable for use in preventing sticking of the web and a method for controlling the temperature of the dryer roll surface temperature. Regarding

[0002]

2. Description of the Related Art Generally, a paper machine comprises a former section for dewatering a raw material liquid to form a paper layer, and a press section for squeezing and dewatering a wet paper web (hereinafter simply referred to as a web) formed in the former section. And a dryer part for sequentially heating and drying the web dehydrated in the press part on a plurality of dryer rolls, and a calendar part for adjusting the thickness of the web dried in the dryer part and the smoothness of the web surface, etc. It consists of a reel part that winds the web into a roll. In addition, in some paper machines, in addition to this, there may be a size section for applying a sizing agent and a coater section for performing surface coating.

In such a paper machine, a high-speed paper machine for newsprint paper or printing / information paper which makes a web at a papermaking speed of 2000 m / min or more has been put into practical use today. In order to increase the speed of the paper machine as described above, it is important to take measures against paper breakage, especially in the dryer section following the press section. That is, when the web is pressed against a metal surface in a state where the moisture content is high (for example, the moisture content is 55 to 45%), an ironing effect caused by uneven drying in the paper thickness direction,
Also, the web easily sticks to the metal surface due to the dirt caused by the adhesive substance contained in the raw material liquid of the web adhered to the metal roll (hereinafter, the phenomenon that the web sticks to the metal roll surface is referred to as the sticking phenomenon). . For this reason, when peeling the wet paper web from the metal surface, it is necessary to apply tensile tension to the web.

In the conventional dryer section, the web circulates on a large number of dryer rolls while being pressed by the canvas onto the surface of the dryer roll of the dryer. The canvas is the outer circumference of a plurality of dryer rolls (for example, 3 to
5) are wound around in a loop, which is referred to as a "dryer group". The paper machine dryer is generally composed of 5 to 7 groups, although it depends on the papermaking speed and the papermaking.

In the dryer unit, when the paper is peeled off from the dryer roll, a difference in operation speed is given between the dryer groups, and the operation speed is made higher toward the dryer group on the downstream side to give tensile tension to the web. . At this time, since the web strength is low, paper breakage easily occurs in the dryer part, particularly in the front part of the dryer where the moisture content of the web is high.

Particularly, in a high speed paper machine, the former section and the press section are made into a non-open draw. That is, since the web is always transferred to the dryer section while at least one side of the web is supported (the one side of the web is covered),
If a web defect occurs in the former and press sections,
Web defects are often discovered only after they are transferred to the front of the dryer.
This helps increase the frequency of paper breaks in the front of the dryer.

Such an increase in the frequency of occurrence of paper breakage in the dryer part, particularly in the front part of the dryer, reduces the productivity of the high speed paper machine.

[0008]

The peeling force required to separate the web from the dryer roll depends on the strength of sticking. This depends not only on the water content of the web but also on the temperature difference between the web and the dryer roll. Also knows to depend on. This is because when there is a temperature difference between the web and the dryer roll, uneven drying occurs in the thickness direction of the web, and the ironing effect of this causes the web to stick strongly to the dryer roll.

If this sticking (sticking) does not occur in the portion where the web is transferred from the dryer roll to the reverse roll, the web is supported on one side by the canvas, but when sticking occurs, the web is separated from the canvas. You lose all your support. Further, the separation point (or paper separation point) of the web in the state where the web is separated from the dryer roll due to sticking easily becomes unstable when affected by the entrained flow of the rotating dryer roll, and this tendency tends to occur. Is more noticeable during high-speed driving. For this reason, if sticking occurs, the stability of the peeling point may be further reduced, and the paper may be broken.

As a current general measure against the above problems, the web is pulled from the surface of the dryer roll by lowering the temperature of the dryer roll in front of the dryer to reduce the temperature difference between the web and the dryer roll. A method of reducing the peeling force required for peeling is used. By the way, in a conventional paper machine dryer, steam heating is generally performed inside the dryer, and the web moisture content at the outlet of the dryer is adjusted to a set value by controlling the supply steam pressure.

Further, a large number of dryer rolls are divided into several groups, and as the downstream group, that is, the dryer group at the position where the drying process is advanced, the dryer group is constituted by as many dryer rolls as possible. By supplying the filled vapor pressure in a cascade manner from the side dryer group to the most upstream dryer group, the most upstream dryer group has the lowest vapor pressure (that is, the dryer roll surface temperature is the lowest) and the most downstream dryer. When stripping the web from the dryer roll surface by maximizing the vapor pressure of the group (ie, increasing the dryer roll surface temperature) to reduce the temperature difference between the dryer upstream web and the dryer roll. The required peeling force is reduced.

However, the conventional paper machine dryer does not control the temperature according to the surface temperature of the dryer roll and the moisture content of the web, and cannot cope with the fluctuation of the papermaking conditions whose time response is several hours. For example, even if the raw material supply system fluctuates and the basis weight or moisture content of the web at the dryer inlet fluctuates, in the conventional paper machine dryer, the dryer supply vapor pressure is adjusted based on the moisture content data after the dryer outlet. Since it is only set, it is not possible to achieve both the sticking suppression in each dryer roll and the achievement of the predetermined moisture content at the dryer outlet, and it is inevitable to reduce the production efficiency.

Further, in Japanese Unexamined Patent Publication (Kokai) No. 5-247872, a temperature reducing device is provided after the vapor pressure control valve of each dryer group to a level slightly higher than the saturation temperature of the vapor pressure reduced by the vapor pressure control valve. A technique is disclosed in which the steam temperature is reduced to reduce the degree of superheat of the steam, whereby the steam condensation in the axial direction of the dryer roll surface is made uniform, and the web is uniformly dried.

However, the above publication does not disclose or suggest a method for setting the vapor pressure between the dryer groups for the purpose of preventing sticking, and of course, it depends on the dryer roll surface temperature and the web moisture content. There is no disclosure or suggestion of temperature control means. The present invention was devised in view of the above-mentioned problems, and by controlling the dryer roll surface temperature based on the dryer roll surface temperature and the web moisture content, it is possible to more reliably prevent sticking of the web on the dryer roll surface. It is an object of the present invention to provide a paper machine dryer and a temperature control method thereof.

[0015]

Therefore, a paper machine dryer of the present invention (claim 1) has a plurality of dryer rolls and sequentially presses the webs against the dryer rolls while sequentially winding the webs around the dryer rolls. A paper machine dryer for drying the web by means of a dryer roll surface temperature detection means for detecting the surface temperature of the dryer roll, a web moisture content acquisition means for detecting or estimating the moisture content of the web, and the dryer. It is characterized by comprising control means for controlling the surface temperature of the dryer roll based on the detection information from the roll surface temperature detection means and the web moisture content from the web moisture content acquisition means.

It is preferable that the control means controls the dryer roll surface temperature so that the dryer roll surface temperature and the web moisture content do not enter a region where sticking of the web occurs on the dryer roll surface (claim). Item 2). The control means preferably controls the dryer roll surface temperature so that the moisture content at the outlet of the paper machine dryer satisfies a desired value (for example, 25 to 3%, preferably 15 to 5%) ( Claim 3). Also, by adjusting the dryer operating conditions (for example, the ambient atmosphere of the dryer such as temperature and humidity and the moisture content at the web inlet) together with or instead of controlling the dryer roll surface temperature. The moisture content at the outlet of the dryer may be adjusted to a desired value.

It is preferable that the control means is a device that supplies steam to each of the dryer rolls individually or collectively while controlling the steam pressure (claim 4). It is preferable that the dryer roll surface temperature detecting means is provided for each dryer roll for the upstream dryer roll, and is provided for only one of the plurality of dryer rolls for the downstream dryer roll. Item 5).

The plurality of dryer rolls are divided into at least two dryer groups, the dryer roll surface temperature detecting means detects the surface temperature of the dryer roll for each dryer group, and the control means It is preferable to control the surface temperature of the dryer roll for each dryer group based on the detection information from the dryer roll surface temperature detecting means (claim 6).

It is preferable that the dryer roll surface temperature detecting means detects the surface temperature of the most upstream dryer roll belonging to each of the dryer groups as a representative temperature of each dryer group (claim 7). It is preferable that the dryer roll surface temperature detecting means detects a surface temperature of an exposed portion of the dryer roll on which the web is not wound (claim 8).

It is preferable that the dryer roll surface temperature detecting means detects the temperature of the surface portion at the center of the dryer roll in the axial direction (claim 9). The dryer roll includes a dryer roll shell around which the web is wound, and a dryer roll head which is provided on both sides of the dryer roll shell and connects the rotary shaft of the dry roll shell and the dryer roll shell. Preferably, the dryer roll surface temperature detecting means detects the temperature of the dryer roll head portion (claim 10).

It is preferable that the dryer roll surface temperature detecting means detects the dryer roll surface temperature at a nip portion formed by the dryer roll and a canvas running along the dryer roll (claim 11).
The dryer roll surface temperature detecting means is preferably a non-contact type radiation thermometer (claim 12).

The dryer roll surface temperature detecting means is preferably a thermocouple which contacts the dryer roll surface and detects the dryer roll surface temperature (claim 1).
3). The dryer roll surface temperature detecting means is preferably a thermocouple that detects the dryer roll surface temperature without contacting the dryer roll surface (claim 14). It is preferable that the web moisture content acquisition unit is a calculation unit that obtains the web moisture content by calculation (claim 1).
5).

The web moisture content acquisition means is preferably a web moisture content detection means for detecting the web moisture content (claim 16). It is preferable that the web moisture content detecting means detects the moisture content at the center of the web in the width direction (claim 17). It is preferable that the web moisture content detecting means detects the moisture content of the web at a position in the paper width direction through which the tail passes when the paper is threaded (claim 18).

The web moisture content detecting means is preferably a non-contact moisture content sensor, such as an infrared moisture meter (claim 19). A method for controlling a temperature of a paper machine dryer according to the present invention (claim 20), wherein the web is dried by pressing the web against the dryer roll while sequentially winding the web around the dryer roll. A temperature control method for a machine dryer, wherein the dryer roll surface temperature and the web moisture content are acquired, and the surface temperature of the dryer roll is an appropriate temperature based on the obtained dryer roll surface temperature and web moisture content. It is characterized in that whether or not there is a region is judged, and if the dryer roll is not in the proper temperature region, the surface temperature of the dryer roll is controlled.

It is preferable to control the dryer roll surface temperature so that the dryer roll surface temperature and the web moisture content do not enter the region where sticking of the web occurs on the dryer roll surface (claim 2).
1). It is preferable that the control of the surface temperature of the dryer roll is periodically performed at a predetermined cycle, and the cycle is set according to the control response time of the surface temperature of the dryer roll (claim 22).

The surface temperature of the dryer roll is controlled as follows.
It is preferable that the water content at the outlet of the paper machine dryer is set so as to satisfy a desired value (for example, 25 to 3%, preferably 15 to 5%) (claim 23). Also, by adjusting the dryer operating conditions (for example, the ambient atmosphere of the dryer such as temperature and humidity and the moisture content at the web inlet) together with or instead of controlling the dryer roll surface temperature. The moisture content at the outlet of the dryer may be adjusted to a desired value.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. [1] First Embodiment FIGS. 1 to 6 show a paper machine dryer according to a first embodiment of the present invention. FIG. 1 is a schematic cross-sectional view thereof.
Is the wet paper web on the surface of the dryer roll (hereinafter,
A schematic enlarged cross-sectional view for explaining sticking of a web), FIG. 3 is a map showing the relationship between the surface temperature of the dryer roll and the moisture content of the web, and FIG. 4 is a cross-sectional view of the side of the dryer roll. 5 is a diagram for explaining the installation position of the temperature sensor, and FIG. 6 is a schematic circuit diagram showing the dryer vapor supply system (also referred to as a drainage system).

As shown in FIG. 1, the paper machine dryer (dryer section 100) of the present embodiment has a first series connection.
Group to n-th group n dryer groups 1-1 to 1-n
(Hereinafter, denoted by reference numeral 1 unless otherwise specified). The right side in FIG. 1 is the upstream side of the paper machine line, and the web 7 is conveyed from the right side and enters the dryer section 100.

The dryer group 1-1 on the most upstream side is a reverse roll 6-1 (hereinafter, denoted by reference numeral 6 unless otherwise specified).
And dryer rolls 5-1 and 5-2 (hereinafter, denoted by reference numeral 5 unless otherwise specified), and the reverse roll 6
-1 and dryer rolls 5-1 and 5-2 with canvas 16
-1 (hereinafter, indicated by reference numeral 16 unless otherwise specified) has a structure in which they are alternately multiplied.

The canvas 16 has a loop shape, and is guided and rotated by the reverse roll 6, the dryer roll 5 and a plurality of canvas rolls 17 described above. The dryer roll 5 is arranged outside the canvas 16, and the reversing roll 6 is arranged inside the canvas 16. Also,
The dryer roll 5, as shown in FIG. 4, is provided on both sides of the dryer roll shell 5a around which the web 7 is wound, and the rotary shaft of the dryer roll shell 5a and the dryer roll shell 5a are provided. The dryer roll head 5b to be connected is provided. In the following, the dryer roll surface temperature means the temperature of the dryer roll shell 5a.

Then, the web 7 is supported by the upper surface of the canvas 16 and is dried while being sequentially pressed against the surface of the dryer roll 5 by the canvas 16.
The other dryer groups 1-2 to 1-n also have the same structure as the dryer group 1-1, although the numbers of the reverse rolls 6 and the dryer rolls 5 are different. For example, the dryer group 1-2 includes the reverse rolls 6-2 to 6-4 and the dryer rolls 5-3 to 5-.
5 and a canvas 16-2, and the dryer group 1-3 is provided with reverse rolls 6-5 to 6-7, dryer rolls 5-6 to 5-8, and a canvas 16-3.

The dryer section 100 is also provided with a drainage system 200, which supplies steam to the inside of each dryer roll 5,
It controls the surface temperature of the dryer roll 5, and is composed of n drain screw groups 2-1 to 2-n (hereinafter, denoted by reference numeral 2 unless otherwise specified) from the first group to the n-th group. .

Each drain screw group 2 is normally connected to a plurality of dryer rolls 5 and is configured to supply steam to each dryer roll 5. However, in the drain screw system 200 shown in FIG. 1-2-5 are 1 respectively
Connected to two dryer rolls 5 and drain screw group 2-6 ~
The dryer rolls 5 are connected so that the number of 2-n becomes larger toward the downstream side. This is because the front part of the dryer 100 has a higher moisture content in the web 7 and sticking is likely to occur. Therefore, the sticking of the web 7 can be reduced by adjusting the surface temperature of each dryer roll 5 near the upstream side. This is so that it can be done.

The sticking of the web 7 on the surface of the dryer roll 5 will be described with reference to FIGS. 2 and 3. As described above, when the web 7 is pressed against the metal surface (dryer roll surface) with a high water content, the sticking phenomenon of the web 7 causes an ironing effect caused by uneven drying in the web thickness direction, and This is a phenomenon in which the web 7 adheres to the metal surface due to the contamination of the web adhered to the metal surface with the adhesive substance contained in the raw material liquid.

As shown in FIG. 2 (a), if the paper separation point P1 of the web 7 from the dryer roll 5 is substantially at the same position as the point Q where the canvas 16 separates from the dryer roll 5, sticking does not occur. When the web 7 is in such a state, it is called a non-sticking area. Further, as shown in FIG. 2B, the paper separation point P2 of the web 7 with respect to the dryer roll 5 is slightly separated in the rotational direction of the dryer roll 5 from the point Q where the canvas 16 separates from the dryer roll 5 and is stabilized. When it is present, the sticking of the web 7 on the surface of the dryer roll 5 occurs, but the position of the paper separation point P2 with respect to the surface of the dryer roll 5 is stable. However, the paper is easily broken due to the irregular tension variation of the paper web 7.
When the web 7 is in such a state, it is in the sticking stable area.

Further, as shown in FIG. 2 (c), the paper separation point P3 of the web 7 from the dryer roll 5 is farther away in the rotational direction of the surface of the dryer roll 5 than the point Q where the canvas 16 separates from the dryer roll 5. If the web 7 is unstablely moved, sticking of the web 7 on the surface of the dryer roll 5 has occurred. In this state,
Alternatively, if this state continues, paper breakage due to the flapping of the web 7 occurs. The time when the web 7 is in such a state is called the sticking area (also called the sticking unstable area).

It was also found that the sticking or non-sticking state of the web 7 on the surface of the dryer roll 5 as described above can be organized by the relationship between the moisture content of the web and the surface temperature of the dryer roll as shown in FIG.
That is, as a result of detecting the moisture content of the web and the surface temperature of the dryer roll, if the surface temperature of the dryer roll 5 is lowered by a predetermined temperature (for example, T1) in the sticking region C (for example, the position of the point R1), non-sticking is performed. It is possible to go to the area A (for example, the position of the point R2). Also, the sticking stable area B (for example, the point R3
Position), by lowering the dryer roll surface temperature by a predetermined temperature (for example, T2), it is possible to reach the non-sticking region A (for example, the position of point R4).

As described above, by controlling the surface temperature of the dryer roll 5, sticking of the web 7 on the surface of the dryer roll 5 can be efficiently and more reliably prevented. Therefore, in the present embodiment, as shown in FIG. 1, a temperature sensor 8 is provided as a dryer roll surface temperature detecting means for detecting the surface temperature of the upstream dryer roll 5 in the drain screw group 2, and this temperature sensor 8 is provided. Detects the surface temperature of the main dryer roll 5 and keeps the dryer roll surface temperature in the non-sticking region A which is an appropriate temperature region based on the dryer roll surface temperature and the web moisture content, and The sticker of the web 7 can be prevented by optimally controlling the surface temperature of the dryer roll so as to satisfy the set value.

That is, since sticking tends to occur as the moisture content increases, in the present embodiment, the temperature sensor 8 is provided in each dryer roll 5 so that the surface temperature of the dryer roll 5 in the front part of the dryer unit 100 can be measured particularly finely. It is provided. The temperature sensor 8 may be either a contact type sensor or a non-contact type sensor, but a non-contact type radiation thermometer is preferable. Using such a temperature sensor 8 facilitates maintenance and operation.

If a contact type thermocouple is used as the temperature sensor 8, it is possible to measure temperature with high accuracy. Furthermore, if a non-contact type thermocouple is used as the temperature sensor 8,
Since the thermocouple metal of the temperature measuring unit is not likely to wear, the maintenance cost of the temperature sensor 8 can be reduced, and the dryer roll surface temperature can be accurately measured.

On the other hand, in the rear part of the dryer part 100, the web 7 is drier than in the front part of the dryer part 100, and sticking is less likely to occur. Therefore, the surface temperature of the dryer roll 5 on the upstream side in the drain screw group 2 is represented. Detected as temperature,
When the temperature of the dryer roll 5 is controlled,
The temperature of other dryer rolls 5 in the same drain screw group 2 is also controlled at the same time. That is, for example, in the drain screw group 2-6 shown in FIG. 1, only the dryer roll 5-6 is provided with the temperature sensor 8-6, and when the surface temperature of the dryer roll 5-6 is lowered, at the same time,
Other dryer rolls 5-7 within the same drain screw group 2-6,
The surface temperature of 5-8 is also lowered.

The temperature sensor 8 is provided near the exposed portion of the dryer roll 5 on which the web 7 is not wound. Here, as shown in FIG. 1, a temperature sensor 8 is provided below the dryer roll 5 toward the surface of the dryer roll 5. Further, more preferably, the surface temperature at the center of the dryer roll 5 in the axial direction can be measured. As a result, the dryer roll surface temperature at the portion where the web 7 contacts the dryer roll 5 can be reliably detected.

Further, as shown in FIG. 4, a temperature sensor 8 may be arranged near the outer peripheral portion of the dryer roll head 5b on the side of the dryer roll shell 5a (that is, the edge of the surface of the dryer roll 5). As a result, the web 7 does not wrap around the temperature sensor 8 even when a paper break occurs, so that the thermometer side of the temperature sensor 8 is not hindered and the dryer roll surface temperature can be reliably detected.

As shown in FIG. 5, a temperature sensor 8 may be arranged so that the surface temperature at the contact portion (nip portion) between the dryer roll 5 and the canvas 16 can be measured. As a result, the influence of external disturbances such as the reflection of surrounding objects on the mirror-finished dryer roll, which deteriorates the temperature measurement accuracy, can be minimized, and the dryer roll surface temperature can be reliably detected. The temperature sensor 8 may be provided at the position shown by the broken line in FIG.

Further, a plurality of temperature sensors 8 may be provided in the axial direction of the surface of the dryer roll 5, whereby a more detailed dryer roll surface temperature can be measured and the measurement result can be obtained. By controlling the temperature of the surface of the dryer roll 5 by using it, the sticking of the web 7 can be surely prevented. On the other hand, the web moisture content is calculated by a web moisture content acquisition means, specifically, a calculation means for calculating the web moisture content based on the web basis weight, the dryer portion outlet moisture content, the papermaking speed, etc. (dryer drying analysis). The program) allows the web moisture content in each dryer group 1 or each dryer roll 5 to be known.

As described above, in this embodiment, the dryer roll surface temperature obtained by the actual measurement of the temperature sensor 8 and
Based on the web moisture content obtained by the calculation means,
The surface temperature of the dryer roll 5 belonging to each drain screw group 2 can be controlled. Specifically, as shown in FIG. 6, the calculator 11 causes the web 7 to be constantly in the non-sticking area A based on the detection information from the temperature sensor 8 and the web moisture content obtained by the calculator. Yes, and sends a signal to the pressure controller (control means) 12 so that the dryer roll surface temperature is in an optimum state so that the web moisture content at the outlet of the dryer satisfies the set value. Based on the information from the pressure sensor 13 provided in the drain screw group 2, the pressure control valves 4, 18 and 1 are controlled so that the surface of the dryer roll 5 reaches an appropriate temperature.
9 is opened and closed to control the vapor pressure filled in the drain screw group 2.

The temperature controller 10 shown in FIG.
Is configured here to change the emissivity of the radiation thermometer which is the temperature sensor 8 and to display the output value of the temperature sensor 8. Also, each drain screw group 2
Are cascade-connected, the steam and water discharged from each drain screw group 2 are collected in the separator tank 14, the steam is cascade-supplied to the drain screw group 2 on the upstream side, and the water is sucked by the pump 15 to be discharged to the boiler. It is sent to and reused.

Next, the temperature control method of the paper machine dryer in this embodiment will be described with reference to the flowchart shown in FIG. As shown in FIG. 7, after all flags (Flag1, Flag2) are reset to 0 in step S100, in step S102, the web basis weight, the papermaking speed, the dryer supply vapor pressure of each drain screw group 2, the dryer unit 100, and the like. The web moisture content at the outlet (hereinafter referred to as the web outlet moisture content), the dryer roll surface temperature, the ambient atmosphere (temperature and humidity), and the web inlet moisture content are measured in real time. In addition, hereinafter, the web outlet water content is the water content of the web 7 at the outlet of the dryer section 100, and the web inlet water content is the water content of the web 7 at the inlet of the dryer section 100. Is the web 7 that is wound around each dryer roll.
Moisture content.

Then, in step S104, it is determined whether or not the flag (Flag2) is 1. Since the flag (Flag2) is 0 at the start of the control this time, the process proceeds to step S108, and the measured value of the moisture content of the web outlet is set to a preset value of the moisture content of the web outlet (for example, between 3% and 15%). It is determined whether or not it is substantially equal to the predetermined value), and when the measured value of the web outlet water content and the set value are substantially equal, the process proceeds to step S110. Note that step S1
Measured value (or calculated value) of moisture content at web exit at 08
The determination may be made based on whether or not the measured value or the calculated value is within a predetermined region of the web moisture content, and the predetermined value of the web moisture content (a region having no width) It may be determined by whether or not

If the measured value of the moisture content at the web outlet is not equal to the set value, the flag (Flag2) is set to 1 in step S130, and the flag (Flag1) is set in step S132 (whether it is 1 or not). ) Or not [the flag (Flag1) is 0 in the initial stage]. When the flag (Flag1) is 0, the dryer vapor pressure is changed in step S134, and then the dryer ambient atmosphere (temperature, humidity) and the dryer inlet moisture content are changed in step S136.

Then, in step S104, the flag (Flag2) is determined to be 1, and the process proceeds to step S106, in which the above-mentioned web basis weight, paper-making speed, dryer supply vapor pressure of each drain screw group 2, etc. are determined by the dryer drying analysis program. Based on this, the web outlet moisture content and the web moisture content of each dryer roll 5 are calculated. At this time, the dryer roll diameter, the number of dryer rolls, and the like are input in advance as the paper machine dryer specifications and used for calculation.

After that, the process proceeds to step S108, and it is determined whether or not the calculated value of the moisture content at the web exit is substantially equal to the set value of the moisture content at the web exit. In this way, the dryer vapor pressure and the atmosphere around the dryer (temperature, humidity) are changed so that the calculated value (or measured value) of the moisture content at the web outlet is substantially equal to the set value of the moisture content at the web outlet.

Then, in step S108, when the calculated value (or measured value) of the moisture content at the outlet of the web becomes substantially equal to the set value of the moisture content at the outlet of the web, the measured value of the surface temperature of the dryer roll and the moisture content of the web at step S110. The area of the map shown in FIG. 3 where the relation between the dryer roll surface temperature and the web moisture content is determined based on the calculated value of the rate, and the relation between the dryer roll surface temperature and the web moisture content is determined to be the non-sticking region. It is determined whether or not it is in A.

If it is determined in step S110 that it is not in the non-sticking area A (if it is determined that it is the sticking stable area B or sticking area C), the process proceeds to step S120, and the flag (Flag) is set.
It is determined whether 1) is 1 [flag (Flag1) is 0 at the initial stage], and if the flag (Flag1) is 0, in step S122, the dryer group to which the sticker-dried roll 5 belongs Assuming that the dryer vapor pressure fine adjustment plan is set to 1 in step S124, the flag (Flag1) is set to 1, and then step S1 is performed.
Go to 04.

Then, the calculation is executed again by the dryer drying analysis program based on the assumed dryer vapor pressure fine adjustment proposal, and when the calculated value of the web outlet moisture content is not substantially equal to the set value of the web outlet moisture content. , Step S13
0 to step S132, and this time the flag (F
Since lag1) is 1, step S134 is skipped and the process proceeds to step S136, and the ambient atmosphere (temperature, humidity)
The web inlet moisture content is changed, and the calculation is repeated so that the calculated web outlet moisture content becomes substantially equal to the set value.

After the calculated value of the moisture content at the web exit becomes substantially equal to the set value of the moisture content at the web exit, if it is determined in step S110 that the non-sticking area A is not yet reached, the process proceeds to step S120, and this time the flag is set. (F
Since lag1) is 1, the process proceeds to step S126,
The dryer vapor pressure fine adjustment plan is updated, and the above flow is repeated again.

As described above, when the relationship between the dryer roll surface temperature and the web moisture content is not in the non-sticking region A, the relationship between the dryer roll surface temperature and the web moisture content is maintained while maintaining the web outlet moisture content at the set value. Until it falls within the non-sticking region A, the dryer vapor pressure fine adjustment proposal is repeatedly finely adjusted and calculated. When it is determined in step S110 that the flag is in the non-sticking area A, it is determined in step S112 whether the flag (Flag1) is 1. If the flag (Flag1) is not 1, the process returns to the start (no control is performed), and if the flag (Flag1) is 1, the step S114 is performed.
In accordance with the final setting plan, the operation of the steam pressure control valve of the dryer steam supply line is commanded (that is, the opening / closing operation of the pressure control valves 4, 18 and 19 is controlled), and the dryer roll surface temperature is actually adjusted. It Along with this, the ambient atmosphere (temperature and humidity) and the web inlet moisture content finally set in step S136 are also controlled to the final set values.

After the dryer roll surface temperature is adjusted,
It is determined whether or not a predetermined time T3 (for example, 10 minutes) has elapsed (step S116), and when the predetermined time T3 has elapsed, the process returns to the start and the above control is executed again. In addition,
Here, the predetermined time T3 is expected to be taken until the dryer roll surface temperature reaches the target temperature after the pressure control valves 4, 18 and 19 are controlled so that the dryer roll surface temperature reaches the target temperature. Corresponds to the time response. That is, even if the surface of the dryer roll 5 is moving to the target temperature, if the control is restarted, there is a possibility that the accurate target temperature cannot be set. Therefore, in order to avoid this, stand by. The predetermined time T3 for this purpose is provided.

As described above, according to the paper machine dryer of this embodiment, since the temperature sensor 8 for detecting the surface temperature of the dryer roll 5 is provided, the surface temperature of the dryer roll 5 can be monitored in real time during the operation of the paper machine. Based on the dryer roll surface temperature and the calculated web moisture content, the map can be used to determine whether the web 7 is in the sticking state, and the sticking area C or the sticking area can be determined. When it is determined that the temperature is in the stable region B, the setting of the dryer vapor pressure is updated, and when the calculation result based on this setting satisfies the predetermined dryer outlet moisture content, the pressure controller 12 causes the dryer vapor supply line 3 Of the steam supplied to the dryer roll 5 by opening / closing the pressure control valves 4, 18 and 19 of And controls the, in a stable state without extreme fluctuations of the dryer outlet moisture content, the surface temperature of the dryer roll 5, it is possible to control the state of sticking is suppressed.

As a result, it is possible to reliably prevent the sticking of the web 7 on the surface of the dryer roll 5 in a stable state without the extreme fluctuation of the moisture content at the outlet of the dryer, and it is possible to greatly reduce the paper shortage caused by the sticking. The operation efficiency can be improved. In addition, in the front part of the dryer section 100 where sticking is particularly likely to occur, each dryer roll 5 (here, the dryer roll 5
-1 to 5-5) is provided with a temperature sensor 8, the surface temperature of each dryer roll 5 is measured in real time, and the surface temperature of the dryer roll 5 is controlled based on the dryer roll surface temperature and the web moisture content. In addition, sticking can be prevented more efficiently and a predetermined dryer outlet moisture content can be achieved.

If the moisture content of the web in each dryer roll 5 or each dryer group 1 is periodically obtained by the dryer drying analysis program, the surface temperature of the dryer roll is controlled in accordance with the moisture content, thereby varying the raw material supply system. Even if, etc. occur, sticking can be prevented and
A predetermined dryer outlet moisture content can be achieved, and optimum dryer operating conditions can be maintained.

Therefore, the paper breakage caused by the sticking of the web 7 can be significantly reduced, and even if the operation for suppressing the sticking is performed, there is no extreme fluctuation in the moisture content at the dryer outlet, so that the operation efficiency is stable. Can be improved. Since the temperature control of the dryer has low responsiveness, it takes time to control to an appropriate value by simple feedback control, but according to the control of the present embodiment, the dryer supply steam pressure (temperature control element) is assumed. Then, calculate the moisture content at the web outlet with the dryer drying analysis program, and obtain the appropriate value for the dryer supply steam pressure so that the moisture content at the web outlet becomes the set value and the dryer temperature becomes the non-sticking region. Since control is performed, it is possible to quickly control to an appropriate state with one control.

Further, the control of the moisture content at the web outlet is carried out by obtaining an appropriate atmosphere moisture content around the dryer and a proper moisture content at the web inlet.
Since this is also performed, there is also an advantage that the non-sticking region can be surely controlled while the moisture content at the web outlet is set to an appropriate value. In the present embodiment, the determination (step S108) is also performed using the measured value of the moisture content at the web outlet, but the measured value of the moisture content at the web outlet is not used.
All calculated values may be used. In this case,
The steps relating to Flag 2 of are unnecessary.

[2] Second Embodiment The paper machine dryer according to the present embodiment is different from the first embodiment in the method of obtaining the web moisture content. That is, in the first embodiment, the web moisture content is obtained by the dryer drying analysis program, but in the present embodiment, the reverse roll 6 of the dryer unit 100 has a moisture content sensor (web moisture content detection means) as a web moisture content acquisition means. ) 9 and the moisture content sensor 9 directly determines the moisture content of the web 7.

Specifically, the moisture content sensors 9-1 to 9-n shown by broken lines in FIG. 1 (hereinafter, referred to as reference numeral 9 unless otherwise specified)
Is a non-contact moisture content sensor (such as an infrared moisture meter), and is a reverse roll 6 (here, the reverse roll 6-) installed at the rear of the dryer roll 5 provided with a temperature sensor 8. 1-6-5, 6-9, 6-n) are provided toward the center in the width direction of the web 7 which is wound around the surface so that the moisture content of the web 7 can be detected. Since the moisture content sensor 9 is a non-contact sensor, the moisture content of the web 7 can be detected without damaging the web 7, and
Easy maintenance and operation.

As described above, the moisture content sensor 9 has the web 7
Since the moisture content in the widthwise center of the web 7 that is less likely to dry and has less moisture content unevenness is detected compared to the both ends of the paper, even if moisture content unevenness occurs in the paper width direction, it is accurately measured without being affected. You can do it. Further, since the moisture content sensor 9 is provided near the temperature sensor 8 to measure the moisture content of the web 7, it is possible to grasp the relationship between the web moisture content and the dryer roll surface temperature with higher accuracy. ing.

Next, the temperature control method of the paper machine dryer of this embodiment will be described with reference to the flow chart shown in FIG. In the control method shown in FIG. 8, the moisture content of each dryer roll is detected by a sensor, and the web outlet moisture content is calculated based on the sensor. However, other than that, in the first embodiment (FIG. 7). See)).

That is, as shown in FIG.
After resetting both flags (Flag1, Flag2) to 0 in 200, in step S202, the web basis weight, the paper making speed, the dryer supply vapor pressure of each drain screw group 2, the web moisture content at the outlet of the dryer section 100 (web outlet). Moisture content), dryer roll surface temperature, ambient atmosphere (temperature, humidity), web inlet water content, and web moisture content of each part are measured in real time.

Then, in step S204, it is determined whether or not the flag (Flag2) is 1. Since the flag (Flag2) is 0 at the start of the control this time, the process proceeds to step S208, and the measured value of the web outlet moisture content is the preset value of the web outlet moisture content (for example, between 3 and 15%). It is determined whether or not it is substantially equal to the predetermined value), and when the measured value of the moisture content at the web outlet is substantially equal to the set value, the process proceeds to step S210.

When the measured value of the moisture content at the web outlet is not equal to the set value, the flag (Flag2) is set to 1 in step S230, and the flag (Flag1) is set in step S232 (whether it is 1 or not). ) Or not [the flag (Flag1) is 0 in the initial stage]. When the flag (Flag1) is 0, the dryer vapor pressure is changed in step S234, and then the dryer ambient atmosphere (temperature, humidity) and the dryer inlet moisture content are changed in step S236.

Then, in step S204, the flag (Flag2) is determined to be 1, and the process proceeds to step S206, in which the above-mentioned web basis weight, paper making speed, dryer supply vapor pressure of each dray screw group 2, etc. are determined by the dryer drying analysis program. Based on this, the web outlet moisture content and the web moisture content of each dryer roll 5 are calculated. At this time, the dryer roll diameter, the number of dryer rolls, and the like are input in advance as the paper machine dryer specifications and used for calculation.

After that, the process proceeds to step S208, and it is determined whether or not the calculated value of the moisture content at the web exit is substantially equal to the set value of the moisture content at the web exit. In this way, the dryer vapor pressure and the atmosphere around the dryer (temperature, humidity) are changed so that the calculated value (or measured value) of the moisture content at the web outlet is substantially equal to the set value of the moisture content at the web outlet.

Then, in step S208, when the calculated value (or measured value) of the moisture content of the web outlet becomes substantially equal to the set value of the moisture content of the web exit, in step S210, the measured value of the dryer roll surface temperature and the web moisture content are measured. It is determined which region of the map shown in FIG. 3 the relationship between the dryer roll surface temperature and the web moisture content is based on the measured value of the rate, and the relationship between the dryer roll surface temperature and the web moisture rate is the non-sticking region. It is determined whether or not it is in A.

If it is determined in step S210 that the area is not in the non-sticking area A (if it is determined that the area is the sticking stable area B or the sticking area C), the process proceeds to step S220 and the flag (Flag) is set.
1) is 1 [flag (Flag1) is 0 at the initial stage], and if the flag (Flag1) is 0, in step S222, the dryer group to which the sticker-caused dryer roll 5 belongs Assuming that the dryer vapor pressure fine adjustment plan is set to 1 in step S224, the flag (Flag1) is set to 1 and then step S2 is performed.
Go to 04.

Then, the calculation is executed again by the dryer drying analysis program based on the assumed dryer vapor pressure fine adjustment plan, and when the calculated value of the web outlet moisture content is not substantially equal to the set value of the web outlet moisture content. , Step S23
0 to proceed to step S232, and this time the flag (F
Since lag1) is 1, step S234 is skipped and the process proceeds to step S236, and the ambient atmosphere (temperature, humidity)
The web inlet moisture content is changed, and the calculation is repeated so that the calculated web outlet moisture content becomes substantially equal to the set value.

After the calculated value of the moisture content at the web outlet becomes approximately equal to the set value of the moisture content at the web outlet, if it is determined in step S210 that the non-sticking area A is not yet reached, the process proceeds to step S220, and this time the flag is set. (F
Since lag1) is 1, the process proceeds to step S226,
The dryer vapor pressure fine adjustment plan is updated, and the above flow is repeated again.

Thus, when the relationship between the dryer roll surface temperature and the web moisture content is not in the non-sticking region A, the relationship between the dryer roll surface temperature and the web moisture content is maintained while maintaining the web outlet moisture content at the set value. Until it falls within the non-sticking area A, the dryer vapor pressure fine adjustment proposal is repeatedly assumed and calculated. And
When it is determined in step S210 that the flag is in the non-sticking area A, it is determined in step S212 whether the flag (Flag1) is 1. If the flag (Flag1) is not 1, the process returns to the start (no control is performed) and the flag (Flag1)
If 1) is 1, then in step S214,
Operation of the steam pressure control valve of the dryer steam supply line is commanded based on the final setting proposal (ie, pressure control valves 4, 18
And the opening / closing operation of 19 is controlled), and the dryer roll surface temperature is actually adjusted.

After the dryer roll surface temperature is adjusted,
It is determined whether or not a predetermined time T3 (for example, 10 minutes) has elapsed (step S207), and when the predetermined time T3 has elapsed, the process returns to the start and the above control is executed again. The reason for providing the predetermined time T3 is the same as the reason described in the first embodiment, and thus the description thereof is omitted here.

As described above, according to the paper machine dryer of the present embodiment, the moisture content sensor 9 is installed in the vicinity of the temperature sensor 8, and the moisture content of the web 7 conveyed in the dryer section 100 is adjusted by each dryer. By measuring in the vicinity of the roll 5, the relationship between the dryer roll surface temperature and the web moisture content can be known with higher accuracy, and more appropriate control of the dryer roll surface temperature can be performed. Therefore, similar to the effect of the first embodiment, the paper breakage caused by the sticking of the web 7 can be significantly reduced, and even if the operation for suppressing the sticking is performed, there is no extreme variation in the moisture content at the dryer outlet, so that the stability is stable. The operation efficiency can be improved.

[3] Third Embodiment FIG. 9 is a schematic sectional view showing a paper machine dryer according to a third embodiment of the present invention. The paper machine dryer according to the present embodiment differs from the second embodiment in the configurations of the temperature sensor 8 and the moisture content sensor 9. That is, the temperature sensor 8 is provided for each dryer roll 5, and the moisture content sensor 9 is provided for each reverse rotation roll 6.

With this structure, the surface temperature of each dryer roll 5 can be measured, and the moisture content of the web 7 (that is, the web 7 near each dryer roll 5) wound around each reverse roll 6 can be measured. Since the measurement can be performed, the state of the web 7 being conveyed through the dryer roll 5 and the dryer unit 100 can be measured in more detail. In other words, not only the surface temperature of the dryer roll 5 in the front part of the drain screw group 2 but also the surface temperature of the other dryer rolls 5 belonging to the same drain screw group 2 can be measured. It is possible to control the surface temperature of the dryer roll belonging to No. 2. Also, by any chance,
Even if the temperature sensor 8 or the moisture content sensor 9 fails,
Since the measurement can be continued using the remaining temperature sensor 8 or the moisture content sensor 9, the sticking of the web 7 can be continuously prevented.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the first, second, and third embodiments, the drain screw groups 2-6 to 2-n at the rear portion of the dryer unit 100.
Is configured to simultaneously control the surface temperature of a plurality of dryer rolls 5 by pressure control valves 4, 18 and 19.
The dray screw group 2 may be provided for each dryer roll 5. As a result, the surface temperature can be controlled separately for each dryer roll 5, and the sticking of the web 7 on each dryer roll 5 can be prevented.

Further, although the dryer roll surface temperature is controlled by the device for supplying the vapor pressure into the dryer roll 5, the device is not particularly limited to this device.
The dryer roll 5 is equipped with a temperature control device equipped with an induction coil.
It may be installed inside or a temperature control device equipped with an induction heating device may be installed outside the dryer roll 5. Even with such a configuration, the surface temperature of the dryer roll can be reliably controlled so as not to enter the region where sticking of the web 7 occurs.

Further, the moisture content sensor 9 may be arranged so that the moisture content of the web 7 can be detected at the position in the paper width direction through which the tail passes when the paper is threaded. As a result, the web moisture content can be stably measured not only during operation but also during paper threading, and if the dryer roll surface temperature is controlled based on this detection result, web sticking can be prevented more reliably. can do. Further, although the tail is normally passed through the end portion in the paper width direction, the same effect as above can be obtained even when the tail does not pass through the end portion in the paper width direction.

[0085]

As described in detail above, according to the paper machine dryer of the present invention as set forth in claim 1, the surface temperature of the dryer roll is detected by the dryer roll surface temperature detecting means,
The moisture content of the web is detected or estimated by the moisture content acquisition means of the web, and the surface temperature of the dryer roll is controlled by the control means based on the moisture content of the dryer roll and the moisture content of the web. It is possible to reliably prevent the web from sticking to the surface of the dryer roll (that is, sticking). Further, even if the raw material supply system fluctuates, it is possible to maintain the optimum dryer operating condition corresponding to the fluctuation, so that the sticking of the web can be prevented as in the above case.

According to the paper machine dryer of the present invention as set forth in claim 2, the control means has a dryer roll surface so that the dryer roll surface temperature and the web moisture content do not enter the region where sticking of the web occurs on the dryer roll surface. Since the temperature is controlled, the sticking of the web can be surely prevented.

According to the paper machine dryer of the present invention as defined in claim 3, the moisture content at the outlet of the paper machine dryer satisfies a desired value (for example, 25 to 3%, preferably 15 to 5%). Since the control means controls the surface temperature of the dryer roll, it is possible to achieve a predetermined moisture content at the dryer outlet without extreme fluctuations in the moisture content at the dryer outlet. Further, since the dryer roll surface temperature is controlled so that the dryer roll surface temperature and the web moisture content do not enter the region where sticking of the web occurs on the dryer roll surface, sticking can be performed while achieving a desired dryer outlet moisture content. It can be surely prevented. Therefore, it is possible to greatly reduce the paper breakage caused by the sticking of the web, and since there is no extreme fluctuation in the moisture content at the dryer outlet, it is possible to stabilize the operation and improve the operation efficiency.

According to the paper machine dryer of the present invention as defined in claim 4, the control means is a device for supplying steam to each dryer roll individually or collectively while controlling the steam pressure. The dryer roll surface temperature can be reliably controlled so as not to enter the area where sticking occurs.

According to the fifth aspect of the paper machine dryer of the present invention, the dryer roll surface temperature detecting means is provided for each dryer roll for the upstream dryer roll and a plurality of dryer rolls for the downstream dryer roll. Since only one of them is provided, the surface temperature can be finely controlled on the upstream side, and the surface temperature can be roughly controlled on the downstream side. Therefore, it is possible to surely prevent the sticking of the web, which tends to occur particularly in the front part of the dryer.

According to the sixth aspect of the paper machine dryer of the present invention, a plurality of dryer rolls are divided into at least two dryer groups, and the dryer roll surface temperature detecting means allows the surface temperature of the dryer rolls to be different for each dryer group. Is detected and the control means controls the dryer roll surface temperature for each dryer group based on this detection information, so that sticking of the web can be reliably prevented.

According to the paper machine dryer of the present invention as defined in claim 7, the dryer roll surface temperature detecting means detects the surface temperature of the most upstream dryer roll belonging to each dryer group as a representative temperature of each dryer group. Therefore, among the dryer rolls belonging to each dryer group, the surface temperature of the dryer roll on the upstream side where sticking may particularly occur can be known, and based on this, the surface temperature of the dryer roll of the dryer group to which this dryer roll belongs Can be controlled.

According to the paper machine dryer of the present invention as defined in claim 8, the dryer roll surface temperature detecting means detects the surface temperature of the exposed portion of the dryer roll on which the web is not wound, so that the dryer roll can be reliably carried out. The surface temperature of can be detected. According to the paper machine dryer of the present invention as set forth in claim 9, since the temperature of the surface portion at the center of the dryer roll in the axial direction is detected by the dryer roll surface temperature detecting means, the dryer at the portion where the web comes into contact with the dryer roll. The roll surface temperature can be reliably detected.

According to the paper machine dryer of the tenth aspect of the present invention, the temperature of the dryer roll head portion connecting the dryer roll shell to the dryer roll rotation shaft is detected by the dryer roll surface temperature detecting means. Even if occurs, the web is not wrapped around the dryer roll surface temperature detecting means, and the dryer roll surface temperature can be reliably detected.

According to the paper machine dryer of the present invention as set forth in claim 11, since the dryer roll surface temperature detecting means detects the dryer roll surface temperature at the nip portion formed by the dryer roll and the canvas, the dryer with mirror surface is used. It is possible to minimize the influence of disturbances such as the reflection of surrounding objects on the roll, which deteriorates the temperature measurement accuracy, and to reliably detect the dryer roll surface temperature.

According to the paper machine dryer of the twelfth aspect of the present invention, since the dryer roll surface temperature detecting means is a non-contact type radiation thermometer, maintenance operation is easy. According to the paper machine dryer of the present invention as set forth in claim 13, since the dryer roll surface temperature detecting means is a thermocouple which comes into contact with the dryer roll surface to detect the dryer roll surface temperature, the dryer roll surface temperature can be accurately measured. It can be measured.

According to the paper machine dryer of the present invention as set forth in claim 14, the dryer roll surface temperature detecting means is a thermocouple for detecting the dryer roll surface temperature without contacting the dryer roll surface. The thermocouple metal is not worn, the maintenance cost of the dryer roll surface temperature detecting means can be reduced, and the dryer roll surface temperature can be accurately measured.

According to the paper machine dryer of the present invention as set forth in claim 15, since the web moisture content obtaining means is a computing means for obtaining the web moisture content by calculation, each dryer roll can be obtained by inputting necessary parameters. The surface temperature of can be calculated. According to the paper machine dryer of the present invention as set forth in claim 16, since the web moisture content acquisition means is a web moisture content detection means for detecting the web moisture content, the web moisture content can be measured, and the measured value can be used for the dryer roll. By using it for controlling the surface temperature, sticking of the web can be prevented more reliably.

According to the paper machine dryer of the present invention as set forth in claim 17, the web moisture content detecting means is less likely to dry than the both ends of the web 7 and has less moisture content unevenness. Therefore, even if moisture content unevenness occurs in the paper width direction, it can be measured accurately without being affected by it, and by controlling the dryer roll surface temperature based on this detection result, it can be performed more reliably. Web sticking can be prevented.

According to the paper machine dryer of the eighteenth aspect of the present invention, the web moisture content detecting means detects the moisture content of the web at the position in the paper width direction through which the tail passes during the paper threading. The web moisture content can be stably measured even when the paper is threaded, and the sticking of the web can be more reliably prevented by controlling the dryer roll surface temperature based on the detection result.

According to the paper machine dryer of the nineteenth aspect of the present invention, since the web moisture content detecting means is a non-contact moisture content sensor, maintenance and operation are easy. Claim 20
According to the temperature control method for the paper machine dryer of the present invention described above, sticking of the web can be reliably prevented. Further, even if the raw material supply system fluctuates, it is possible to maintain the optimum dryer operating condition corresponding to the fluctuation, so that the sticking of the web can be performed while satisfying the predetermined moisture content at the dryer outlet in the same manner as above. Can be prevented. As a result, it is possible to reduce paper breakage of the web caused by sticking without extreme fluctuations in the moisture content at the dryer outlet, and improve the operating efficiency of the paper machine.

According to the temperature control method for a paper machine dryer of the present invention as defined in claim 21, a control means is provided so that the dryer roll surface temperature and the web moisture content do not enter a region where sticking of the web occurs on the dryer roll surface. Since the dryer roll surface temperature is controlled by, the sticking of the web can be reliably prevented. According to the temperature control method for a paper machine dryer of the present invention as set forth in claim 22, control of the dryer roll surface temperature is periodically performed at a predetermined cycle, and this cycle is determined according to the control response time of the surface temperature of the dryer roll. Since the temperature is set, it is possible to prevent temperature control from being performed again while the surface temperature of the dryer roll is changing, and the surface temperature of the dryer roll can be reliably set to the target temperature.

According to the temperature control method of the paper machine dryer of the present invention as defined in claim 23, the water content at the outlet of the paper machine dryer has a desired value (for example, 25 to 3%, preferably 1).
(5 to 5%), it is possible to prevent extreme fluctuations in the moisture content at the dryer outlet, and to reliably maintain the moisture content at the dryer outlet at the set value.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing a paper machine dryer according to a first embodiment of the present invention.

FIG. 2 is a schematic enlarged cross-sectional view for explaining sticking of the web on the dryer roll surface of the paper machine dryer according to the first embodiment of the present invention.

FIG. 3 is a map showing the relationship between the dryer roll surface temperature and the web moisture content of the paper machine dryer according to the first embodiment of the present invention.

FIG. 4 is a cross-sectional view schematically showing a dryer roll side portion of the paper machine dryer according to the first embodiment of the present invention.

FIG. 5 is a schematic sectional view showing an installation position of a dryer roll surface temperature detecting means of the paper machine dryer according to the first embodiment of the present invention.

FIG. 6 is a schematic circuit diagram showing a vapor supply system (drain screw system) of the paper machine dryer according to the first embodiment of the present invention.

FIG. 7 is a flowchart showing a temperature control method for a paper machine dryer according to the first embodiment of the present invention.

FIG. 8 is a flowchart showing a temperature control method for a paper machine dryer according to a second embodiment of the present invention.

FIG. 9 is a schematic sectional view showing a paper machine dryer according to a third embodiment of the present invention.

[Explanation of symbols]

1, 1-1 to 1-n Dryer group 2, 2-1 to 2-n Dry screw group 3 Dryer steam supply line 4 Pressure control valve 5, 5-1 to 5-n Dryer roll 5a Dryer roll shell 5b Dryer roll head 6,6-1 to 6-n Reverse roll 7 Web 8,8-1 to 8-n Temperature sensor (dryer roll surface temperature detecting means) 9,9-1 to 9-n Moisture content sensor (web moisture content acquisition means) , Web moisture content detection means) 10 temperature controller 11 arithmetic unit 12 pressure controller (control means) 13 pressure sensor 14 separator tank 15 pump 16 canvas 17 canvas roll 100 dryer section 200 steam supply system (drain screw system)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takashi Nagaoka             Hiroshima Prefecture Mihara City Itozakicho 5007 Mitsubishi Heavy Industries             Paper and printing machinery division F term (reference) 4L055 BD07 CF04 CF50 DA14 DA18                       DA25 FA22 FA30

Claims (23)

[Claims] 1. A paper machine dryer which has a plurality of dryer rolls and presses the webs against the dryer rolls while sequentially winding the webs around the dryer rolls to dry the webs, the surface temperature of the dryer rolls. Means for detecting the surface temperature of the dryer roll, means for acquiring the moisture content of the web for detecting or estimating the moisture content of the web, detection information from the surface temperature detecting means for the dryer roll, and web moisture content from the means for obtaining the moisture content of the web. And a control means for controlling the surface temperature of the dryer roll based on the rate. 2. The control means controls the dryer roll surface temperature so that the dryer roll surface temperature and the web moisture content do not enter a region where sticking of the web occurs on the dryer roll surface. The paper machine dryer according to claim 1. 3. The control means controls the dryer roll surface temperature so that the moisture content at the outlet of the paper machine dryer satisfies a desired value.
Or the paper machine dryer according to 2. 4. The control means is a device for supplying steam to the dryer rolls individually or collectively while controlling the steam pressure.
The paper machine dryer according to any one of 3 above. 5. The dryer roll surface temperature detecting means comprises:
5. The upstream dryer roll is provided for each dryer roll, and the downstream dryer roll is provided for only one of the plurality of dryer rolls. The paper machine dryer according to item 1. 6. The plurality of dryer rolls are divided into at least two dryer groups, and the dryer roll surface temperature detecting means detects the surface temperature of the dryer roll for each dryer group, and the controlling means. The papermaking machine according to any one of claims 1 to 4, characterized in that the surface temperature of the dryer roll is controlled for each dryer group based on the detection information from the dryer roll surface temperature detecting means. Machine dryer. 7. The dryer roll surface temperature detecting means comprises:
7. The paper machine dryer according to claim 6, wherein the surface temperature of the dryer roll on the most upstream side of each of the dryer groups is detected as a representative temperature of each dryer group. 8. The dryer roll surface temperature detecting means comprises:
The surface temperature of the exposed portion of the dryer roll on which the web is not wound is detected.
7. The paper machine dryer according to any one of 7 above. 9. The dryer roll surface temperature detecting means comprises:
9. The paper machine dryer according to claim 1, wherein the temperature of the surface portion of the dryer roll in the axial direction is detected. 10. The dryer roll is provided with a dryer roll shell around which the web is wound, and dryers provided on both sides of the dryer roll shell and connecting a rotary shaft of the dry roll shell and the dryer roll shell. 8. A paper machine dryer according to claim 1, further comprising a roll head, wherein the dryer roll surface temperature detecting means detects the temperature of the dryer roll head portion. 11. The dryer roll surface temperature detecting means detects the dryer roll surface temperature of a nip portion formed by the dryer roll and a canvas that runs along the dryer roll. The paper machine dryer according to any one of Items 1 to 7. 12. The paper machine dryer according to claim 1, wherein the dryer roll surface temperature detecting means is a non-contact type radiation thermometer. 13. The dryer roll surface temperature detecting means is a thermocouple for contacting the dryer roll surface to detect the dryer roll surface temperature. Paper machine dryer described in. 14. The dryer roll surface temperature detecting means is a thermocouple for detecting the dryer roll surface temperature without contacting the dryer roll surface. Paper machine dryer described in. 15. The paper machine dryer according to claim 1, wherein the web moisture content obtaining unit is a computing unit that obtains the web moisture content by computation. 16. The paper machine dryer according to claim 1, wherein the web moisture content acquisition means is a web moisture content detection means for detecting the web moisture content. 17. The paper machine dryer according to claim 16, wherein the web moisture content detecting means detects the moisture content at the center in the width direction of the web. 18. The paper machine dryer according to claim 16, wherein the web moisture content detecting means detects the moisture content of the web at a position in the paper width direction through which the tail passes when the paper is threaded. 19. The web moisture content detecting means is a non-contact moisture content sensor.
18. The paper machine dryer according to any one of 18 items. 20. A method for controlling a temperature of a paper machine dryer, comprising a plurality of dryer rolls, the web being sequentially wound around the dryer rolls, and the webs being pressed against the dryer rolls to dry the webs. The roll surface temperature and the web moisture content are acquired, and it is determined whether or not the surface temperature of the dryer roll is in an appropriate temperature range based on the obtained dryer roll surface temperature and web moisture content, and the dryer is used. A temperature control method for a paper machine dryer, comprising controlling the surface temperature of the dryer roll if the roll is not in an appropriate temperature range. 21. The dryer roll surface temperature is controlled so that the dryer roll surface temperature and the web moisture content do not enter a region where sticking of the web occurs on the dryer roll surface. 20. A method for controlling a temperature of a paper machine dryer according to item 20. 22. The control of the dryer roll surface temperature is periodically performed in a predetermined cycle, and the cycle is set according to a control response time of the surface temperature of the dryer roll. The temperature control method for a paper machine dryer according to claim 20 or 21. 23. The control of the dryer roll surface temperature is performed so that the moisture content at the outlet of the paper machine dryer satisfies a desired value. The method for controlling the temperature of the paper machine dryer according to the paragraph.