JP2909285B2 - Paper machine dryer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 7 shows a conventional paper machine dryer.
The outline will be explained in the next section. In FIG. 7, 1 is a dryer roll,
Reference numeral 2 denotes a transport roll that transports the wet paper while sucking it, 3 denotes a canvas that travels while holding the wet paper, 4 denotes a ventilation duct that blows dry hot air onto the transport roll 2, and 5 denotes an entire dryer. Hood, 6 is an air supply fan for supplying low-humidity dry air into the hood 5, 7 is an exhaust fan for discharging humid air in the hood from the hood ceiling, and 8 is a humid air passing through the inner roll of the transport roll 2. The drawing shows an exhaust fan sucking paper. The transport roll 2 has a double structure roll, and an inner roll is connected to a suction system. FIG. 8 is an enlarged view of the vicinity of the dryer roll 1, the transport roll 2, the canvas 3, and the wet paper 9 roll.

Next, the drying process of wet paper will be described.
The wet paper web 9 is held on the canvas 3 and first contacts the dryer roll 1. Steam is supplied to the dryer roll 1 by a steam piping system (not shown) and a rotary joint (not shown), and heat is supplied to the wet paper web 9 from the roll surface. Although the absolute amount varies depending on the position of the dryer roll in the machine flow direction, evaporation from the wet paper gradually occurs.
Here, from the ventilation duct 4, the transport roll 2
Dry hot air is supplied to the upper wet paper surface to promote moisture evaporation. The transport roll 2 in the next process is a canvas 3
The wet paper web 9 is conveyed while being constrained by suction, and has a maximum vacuum value of several hundred mmAq. The purpose of the restraint is to prevent shrinkage (shrinkage) in the width direction of the wet paper due to drying. The wet paper web 9 that has exited the transport roll 2 moves again to the adjacent dryer roll 1 and repeats the same process. FIG.
In this case, the dryer roll 1 is in contact only with the same side of the wet paper web. However, it is also possible to adopt a structure in which the opposite side of the wet paper web comes into contact with the dryer roll every several dryer rolls.
Now, the vapor evaporated in FIG.
Move as indicated by the arrow due to the dry air supplied from the air.
In other words, it flows toward the ceiling as an upward flow, and the other part becomes an entrainment flow of the rolls, flows in the direction of the transport rolls 2, and goes out of the system from its exhaust system. Some also diffuse into the hood. Further, on the transport roll 2, the evaporated water is partially sucked into the roll through the canvas. In FIG. 7, a hood 5 that covers the dryer is provided with an air supply fan 6, an exhaust fan 7 from the ceiling, and an exhaust fan 8 for suctioning the transport roll 2. Each fan is actually arranged in several pieces, but in FIG.
It is made into pieces.

[0004] The purpose of the air supply fan 6 is to blow dry air into the hood. The ceiling exhaust fan 7 discharges humid air containing moisture evaporated from the wet paper in the hood to the outside of the system, and gives heat to the air supplied to the air supply fan 6 through the heat exchanger 10. Further, as described above, the suction and exhaust fan 8 for the transport roll 2 is used to restrain the wet paper web from shrinkage. However, the suction and exhaust fan 8 is also high-temperature air containing high moisture and is usually the same as the ceiling exhaust fan 7. In the system, the air is discharged out of the system, heat is supplied to the supply air by the heat exchanger 10, and the heat is discharged out of the system. Therefore, again, at present, the moisture evaporated on the dryer roll surface is
Removed by hot dry air from Some of them are sucked by the suction system exhaust fan 8 in the transport roll 2 by the entrainment flow and go out of the system. Further, a part thereof is diffused into the hood, and finally becomes an upward flow and is discharged from the ceiling exhaust fan 7 to the outside of the system.

[0005]

In the dryer of the conventional paper making machine, it has been found that the suction air of the transport roll 2 has a relatively high humidity. Although the air exhausted from the ceiling (by the exhaust fan 7) still has a high humidity, according to a study by the present inventors, the absolute value of the air exhausted from the ceiling is lower than that of the transport unit. It was humidity. The provision of a system for discharging to the outside of the system under these conditions, and two systems for transport and ceiling have enormous amounts of energy in terms of power use, and need to be improved. An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a paper machine dryer capable of efficiently removing high-humidity air and reducing power (energy saving).

[0006]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a dryer having a plurality of dryer rolls to which steam for heating and drying wet paper is supplied, and an exhaust line for sucking wet paper disposed between the dryer rolls. In a dryer of a papermaking machine including a wet paper web transfer roll having a wet paper web and a canvas running while holding the wet paper web, a cover is provided in the vicinity of the wet paper web transfer roll.
And a device for controlling the suction pipe from the transport roll based on a signal from the detecting unit. Means.

[0007]

[Function] By installing a cover near the wet paper web transfer roll.
Ri, only air humid intensively collected in the portion Shimekami搬
Exhaust more efficiently than the feed roll. Also check the humidity of the same part.
By adjusting the number of revolutions of the exhaust blower according to the degree of humidity, the optimum wetness near the wet paper is adjusted according to the basis weight and moisture content of the paper.
Degree, and by optimizing the blower speed,
It is possible to save energy on power.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an embodiment of the present invention; FIG. First, in FIG. 1, 1 is a dryer roll, 2 is a transport roll, and 11 and 1
Reference numeral 1 'denotes an example of a cover, in which the conveying roll 2 and the ventilation duct 4 are surrounded by a cover 11', and the dryer roll 1 is surrounded by a cover 11. The shape and material of the cover are not limited. If the cover is arranged so as to surround the transport roll 2 and the ventilation duct 4 and further cover the dryer roll 1, the cover may be included including the quantity. However, it does not specify the position of the transport roll, the position of the dryer roll, or the like where the roller is disposed. Various types of coverings are conceivable as shown in FIGS. That is, FIG. 3 shows an example in which a cover 11 ′ equivalent to FIG. 1 is provided around the transport roll 2 and the ventilation duct 4, and a cover 12 that covers the entirety is provided on the dryer roll 1 side. . FIG. 4 shows an example in which the lower cover of the transport roll 2 is continuously provided as shown in FIG. When the cover is provided, the flow of the humid air is as described later. That is, as shown in FIG. 5, the moisture evaporated on the dryer roll 1 enters the closed space by the entrainment flow as shown by the arrow, and is discharged out of the system by the suction system exhaust fan of the transport roll 2. By disposing the cover in this manner, it is possible to greatly reduce the rate of diffusion in the hood until now.

On the other hand, although the water in the wet paper is continuously evaporated on the surface of the transport roll 2, the high-humidity air on the circumference of the transport roll does not go out of the closed space, and the inside of the transport roll 2 Is discharged from the suction system exhaust fan 8 to the outside of the system. Therefore, again, by arranging the cover, the air containing a large amount of moisture is intensively collected, and this suction system exhaust fan 8
It is possible to take out of the system. FIG. 8 shows an enlarged view of the conventional case, in which high-humidity air flows upward and escapes to the ceiling side. FIG. 6 is an enlarged view of FIG. 4, but has a configuration in which air with a higher humidity than that of FIG. Therefore, since the humidity in the hood is relatively low in both FIGS. 5 and 6, the ceiling exhaust fan can be throttled,
The power can be reduced. In addition, the method of controlling the ceiling exhaust fan by controlling the humidity or the dew point in the hood is generally performed, and is added here. In the present invention, a sensor 14 for detecting humidity or calculating humidity is further disposed in the closed space in FIG. 1 to control the suction system exhaust fan 8. In FIG. 1, it is installed below the transport roll 2, but the installation location is not limited by placing it in a closed space. Further, the sensor 14 may be arranged in the exhaust system of the transport roll as shown in FIG. As the hygrometer, those generally used at present can be applied, but the type is not limited. In addition, the temperature of the dry bulb and the wet bulb can be measured by a thermocouple and calculated, and the method of measuring the humidity is not limited.

Reference numeral 15 denotes a control device that controls the suction system exhaust fan 8 in response to a signal from the detection sensor. Generally, the basis weight (weight of paper per unit area) depends on the paper type of paper to be made
Fluctuates, the amount of evaporated water in the hood changes.
Therefore, if the basis weight is small, the absolute water evaporation amount is relatively small. For example, if the humidity in the closed space is always kept constant, the suction amount of the exhaust fan can be relatively small. The converse is true for larger basis weights. Usually, in the dryer hood area of a paper company, a method of controlling the humidity in the hood to be constant is adopted.In the present invention, the humidity in a local area such as a closed space around the dryer roll and the transport roll is detected, and the exhaust air is detected. This limits the amount of suction of the fan, and is different from control based on normal detection of humidity in the hood. That is, when the grammage is small, it is possible to reduce the number of revolutions to reduce the power, and when the grammage is large, it is possible to increase the number of revolutions by an amount corresponding to that to enable efficient operation, and Conversely, depending on conditions, the mass transfer of water from the wet paper can be controlled by controlling the humidity depending on the conditions. That is, moisture evaporation can be controlled. In addition, moisture evaporation from wet paper can be controlled, and paper quality can be controlled.

[0011]

As described above, the present invention provides a wet paper web transport
By installing a cover in the vicinity of the high humidity air
Only the same part is concentrated and the exhaust can be exhausted efficiently. Conventional
Because of the exhaust from the ceiling, relatively effective humidity for drying
There was a drawback that low air was discharged together, but this system
According to the system, only air with high humidity and not effective for drying is collected.
It can be discharged out of the system in the middle, improving drying efficiency.
Wear. In addition, the humidity of the exhaust part is detected and the degree of the humidity is detected.
In some cases, adjusting the number of revolutions of the exhaust blower
Always prescribed for the amount of water evaporation that varies according to the basis weight of
Humidity can be set to keep drying quality stable and
For example, when the water content is low, lower the rotation speed of the blower, etc.
Control is possible, and energy saving is achieved by optimizing blower power.
Becomes possible.

[Brief description of the drawings]

FIG. 1 is a system diagram of a dryer according to a first embodiment of the present invention.

FIG. 2 is a system diagram of a dryer according to a second embodiment of the present invention.

FIG. 3 is a side sectional view of a dryer showing a third embodiment of the present invention provided with a cover for covering the whole;

FIG. 4 is a side sectional view of a dryer showing a fourth embodiment of the present invention provided with a cover for covering the whole;

FIG. 5 is an enlarged side sectional view of a main part in FIG. 3;

FIG. 6 is an enlarged side sectional view of a main part in FIG. 4;

FIG. 7 is a system diagram showing a conventional dryer.

FIG. 8 is an enlarged side sectional view of a main part in FIG. 7;

[Explanation of symbols]

 Reference Signs List 1 dryer roll 2 transport roll 3 canvas 4 ventilation duct 5 hood 6 air supply fan 7 ceiling exhaust fan 8 transport roll suction exhaust fan 9 wet paper 10 heat exchanger 11, 11 ', 12, 13 cover 14 humidity detection sensor 15 exhaust Fan control device

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-47383 (JP, A) JP-A-3-89197 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) D21F 5/06 D21F 5/04 D21F 5/18

Claims (1)

(57) [Claims] 1. A wet paper web transport having a plurality of dryer rolls to which steam for heating and drying a wet paper web is supplied, and an exhaust line for suction of the wet paper web arranged between the dryer rolls. In a dryer of a papermaking machine including a canvas and the like running while holding a roll and a wet paper, a cover is provided in the vicinity of the wet paper transport roll, and means for detecting humidity in the cover or in the wet paper transport roll exhaust system, A dryer for a papermaking machine, comprising: a device for controlling a suction pipe from a transport roll based on a signal from the detection means.