The present invention relates to the control of a treatment process, involving compression, drying, coating, calendering, and the like, of a fibrous web consisting of paper, tissue, cardboard, pulp, and the like, e.g., in a paper-, tissue-, cardboard-, or pulp- making machine. More specifically, the object of the present invention is a method and arrangement for the control a fibrous-web treatment process in a fibrous-web machine.

The fibrous-web treatment unit needs effective air-conditioning or air-exchange due to the high moisture evaporation from the fibrous web. Deficient air-condition or air- exchange results in condensation of the moisture in the air on colder surfaces. The air- conditioning and air-exchange must also be implemented evenly in the cross direction (CD) relative to the fibrous web direction of travel or MD (machine direction), so that the fibrous web will not dry unevenly.

It is previously known that the climate of a treatment unit may be controlled by removing moist air and supplying makeup air to the area. An essential weakness of such a solution is the need for great amounts of air and large air-conditioning systems making this solution disadvantageous in terms of investment and operating costs.

Regulating (valving) elements intended for air-treatment and affecting the fibrous web are typically: Water moistener; steam box; chemical-application device; roll-cleaning device; air blowing; drying device; radiation dryer, and other similar device affecting the air-treatment and/or fibrous web - to be permanently installed on a beam in the CD direction. Thus, it is a weakness that suction and makeup-air valves are in a fixed position, and in unfavorable locations in terms of their intended purpose.

To ventilate the immediate environment of a treatment unit, preferably a calender, more preferably a multinip calender, it is previously known that a powerful air exchange is

9S^

needed for strong evaporation, that deficient air-conditioning causes the moisture in the air to condense on colder surfaces, that the air-exchange should be done in the CD direction as evenly as possibly in order to enable even drying, however, air-conditioning solutions are usually fixed installations in the CD direction, e.g., on a beam in the CD direction.

The publication DE 19904891 Cl, representing the closest state of the art, discloses a solution, according to which dried air is blown into the inner space defined by the walls of a calender.

A main object of the present invention is to obtain a device that dries the air in a treatment unit, e.g., with a calender, drying section, condebelt-dryer, and the like, in connection with fibrous-web production or finishing treatment (downstream processing). A second main object of the invention is to enable the control and adjustment of a treatment process with a moving regulating element affecting the air treatment and fibrous web. A third object of the invention is to bring about an air-conditioning solution for ventilating the immediate environment of the treatment unit, preferably a calender, more preferably a multiroll calender.

The main objects of the invention may generally be attained by a method according to the invention for controlling the fibrous- web treatment process in a fibrous-web making machine, whereby the fibrous web travels through a treatment unit, in which at least one heating effect is directed toward the fibrous web by means of a contact, e.g., a roll or cylinder contact, or contactlessly, e.g., by means of airborne web drying or IR-drying (IR, infrared), e.g., such that for the adjustment and/or control of the fibrous-web treatment process in the treatment unit, at least one operation is directed toward the air surrounding the fibrous web in the treatment unit web affecting the moisture of the fibrous web and/or its surrounding air.

According to an example of a method according to the invention considered to be advantageous, air surrounding the fibrous web is dried in connection with the treatment unit by condensing the moisture in an air-cooling and/or drying device and/or moisture- condensing device on a cooled or colder surface.

According to a second example of a method according to the invention considered to be advantageous, air is blown toward the fibrous web in the treatment unit or the air surrounding the fibrous web is aspirated by a regulating element, whose place, location or position is movable. It is therefore advantageous to use a regulating element, such as a blow valve, a suction valve, a nozzle, or a duct system connected with such a regulating element.

The main objects of the invention are also generally achievable by an arrangement according to the invention for controlling the fibrous- web treatment unit in the fibrous- web machine, whereby the fibrous web travels in the treatment unit, in which at least one heating effect is directed toward the fibrous web by means of a contact, e.g., a roll or cylinder contact, or contactlessly, e.g., through airborne web drying or IR-drying (IR, Infrared), e.g., such that for the adjustment and/or control of the fibrous-web treatment process in the treatment unit, at least one operation is directed toward the air surrounding the fibrous web in the treatment unit, having an effect on the moisture of the fibrous web and/or the surrounding air.

According to an example of an arrangement considered advantageous according to the invention, the treatment unit contains a surface which is cooled or colder than the environment in order for the humidity in the air to condense on its surface.

According to a second example of the invention considered advantageous, the regulating element blowing air toward the fibrous web in the treatment unit or aspiring the air surrounding the fibrous web is moveable. It is therefore advantageous that the regulating

element is a blow valve, a suction valve, a nozzle, or the equivalent, or a duct system connected with such a regulating element.

The surface against the fibrous web in the fibrous- web, roll or cylinder contact may be, e.g., a roll, cylinder or belt-metal surface or polymer surface. A contactless effect is obtained as mentioned above, e.g., by drying in an airborne-web drier or IR drier.

The advantages of the invention can be stated as follows: a) In the proximity of a treatment unit, e.g., a calender, a controlled cold drier surface may be arranged, where the moisture is condensed in a controlled fashion without such condensing interfering with the treatment process or the calender, per se. Consequently, the reliability of the fibrous- web machine is increased; b) The treatment-unit environment is cleaner, as the treatment unit does not have any surfaces becoming condensed or dirty; c) A large air-conditioning system may be omitted, or its dimensions may be reduced, so that agitation of great air masses may be eliminated, or at least essentially diminished; d) The condensate may be diverted in a controlled fashion; e) Energy is not consumed, as cooling water is generally available in ample amounts, e.g., in rivers and lakes; f) Energy may also be recovered automatically, e.g., for the cooling water. If desired, energy may be obtained for utilization, admittedly at relative low (30-40 °C) recovery temperatures. With the recovered energy, premises may be heated or the energy fed back into the process; g) The recovered energy may be re-utilized in the fibrous-web machine, e.g., for heating the feed-box stock or the coating-head paste (viscosity may change slightly); h) Condensation and air-conditioning problems are hard to predict in the machine- planning phase, but thanks to the present invention, the air conditioning of the machine may easily be adjusted, e.g., in the machine commissioning stage, and the safety of commissioning the fibrous-web machine may be increased.

The other special features and advantages of the method and arrangement according to the present invention will become clear from the following specification covering some examples of the invention considered advantageous and the attached the list of claims defining the scope of the invention.

The present invention will be described in the following by way of exemplification only, by the (embodiment) examples of the present invention considered advantageous and related to the calender, and with reference to the attached drawings, where:

Fig.l is a schematic representation of the operating principle of a first example of the invention;

Fig.2 is a schematic representation of an air-cooling and/or drying device and/or a moisture-condensing device of an example shown in Fig. 1 ; Fig. 3 is a schematic representation of an air-cooling and/or drying device and/or a moisture condensing device of a second example shown in Fig.l;

Fig. 4 is a schematic representation of a second example of the invention; and

Fig. 5 is a schematic representation of a third embodiment of the invention.

In a method and arrangement according to the examples shown in the figures for controlling the fibrous-web W treatment process, the fibrous web travels through the nip of at least one pair of rolls 31, 32 in the fibrous- web calender 21, 22. In the nip forming between the thermo-roll 31 and the soft-surface roll 32 acting as a opposing roll, a pressure load and a thermal effect, among other things, is directed toward the fibrous web, causing an irreversible deformation in the fibrous web.

As a general feature of the invention, the treatment process of the fibrous web W may be adjusted and/or controlled in the calender 31, 32 by directing at least one operation directed or being directing toward the air surrounding the fibrous web, thereby affecting

the moisture of the fibrous web and/or its surrounding air. Such an operation is typically air-conditioning or drying.

In connection with the present invention, the qualifying phrase "affecting the air surrounding the fibrous web" therefore refers generally to any type of operation to be performed in a fibrous-web W treatment unit 21, 22, 23, such as a compression unit and/or drying unit, especially a drying unit for a papermaking machine and/or cardboard- making machine, or a coating unit or surface-sizing unit, or in a calender, e.g., a multinip calender, a soft calender, a belt calender, a metal-belt calender, or in an equivalent unit affecting the moisture of the fibrous web and/or its surrounding air, whereby the treatment process of the fibrous web may be adjusted and/or controlled by the relevant operation.

Such operations are, e.g., treatment-unit air exchange and/or air-conditioning, reduction of the treatment-unit air mass or the fibrous- web moisture, blowing operations toward to the fibrous web and/or suction operations away from the fibrous web.

Reference is made to Fig. 1. The treatment unit in the embodiment in Figure 1 has a calender 21, 22 consisting of two successive roll systems. The calender may be encased, as indicated by the dotted line. The advantage of the encased calender unit is that the ambient air, e.g., the machine-room air, is separated from the air surrounding the fibrous web. It should be emphasized that the order, type, or nips of rolls, or the path of the fibrous web are not important, per se, for the present invention, since the field of application of the present invention is the influencing of the air surrounding the fibrous web, whereby the field of application of the present invention relates to all fibrous- web- machine units irrespective of the order or type or nips of the roll or rolls.

The fibrous web W in the calender 21, 22 of the example shown in Fig. 1 travels in a winding fashion through the nip. Thus, the influencing of the air surrounding the fibrous

web may be controlled, e.g., by an air-cooling and/or drying device and/or a moisture- condensing device 15 according to Fig. 2, or an air-cooling and/or drying device and/or a moisture-condensing device 16, or an air-conditioning device according to Fig. 3. According to the invention, air circulation for the calender is provided, so that air may recirculate through an air-cooling and/or drying device, and/or a moisture-condensing device 15, 16. In the following and in connection with Figures 2, 3, 4, 5 and 6, reference is made to the air-cooling and/or drying device, and/or the moisture-condensing device, and/or the air-conditioning device by using the term drying unit for the sake of simplicity.

According to an example in Fig. 2, the airflow in the calender 21, 22 occurs through flow gates 11 of the drying unit 15 that are stationary and cooled by a cooling agent. The cooling agent flows in flow channels 2 in separation walls 51 that are arranged to separate the flow gates from one another. Thus the outer surfaces of the separation walls confining the flow gates are cooled and as a result, the moisture of the airflow is condensed on the cold surfaces of the separation walls. Thus the air is dried in the flow channels, and the condensation water released from the air flows as a liquid into the condensate collection means 41 below the separation walls, e.g., a collector tray, and further into a discharge means, e.g., a discharge assembly.

The drying unit 15 of the example shown in Fig. 2 is preferably a heat exchanger operating according to the upstream or downstream principle. In such a heat exchanger, the separation walls 51 and the flow channels 2 for the cooling agents, e.g., cooling water, and the flow gates 11 confined by the separation walls are typically kept stationary

The airflow in the calender 21, 22 according to the example shown in Fig. 3 occurs through a stationary annular channel 12. The annular channel is confined externally by a non-rotating casing part 42, and internally by a rotating heat-exchange cell 52 provided with flow channels 2 for a cooling agent, e.g., cooling water, or cooling-agent circulation. Thus, the rotating external surface of the heat-exchange cell acts as a condensing surface,

on which the moisture of the airflow is condensed and the air dried. The external surface of the heat-exchange cell 52 may be slotted and/or ribbed 53 in order to increase the condensation area.

The inside condensate/condensation water from the external surface is released partly due to the effect of the centrifugal force, and partly by means of, e.g., a rubber scraper blade 43 located on the inside surface of a casing part, e.g., a protective hood, acting on the outer surface casing. Finally, the condensate/condensation water escapes into a condensate/condensation-water collecting means 41, e.g., a collector tray, and further into a discharge means, e.g., a discharge assembly. If the surface of the heat-exchange cell 52 is slotted and/or ribbed, the option of using a scraper blade, however, must be considered carefully.

The fibrous web to be calendered is dried considerably in the calender 21, 22, 23, by as much as five percentage points, as the evaporating water amounts, e.g., on a 10 m wide multi-roll calender, is in the 0.6-1.0 kg/s category. The energy needed for such evaporation is about 1.5-2.0 MW, which in a calender may be produced primarily by means of a thermo-roll 31. Similarly, the evaporating moist air, when precipitating, releases the same amount of energy, as is carried off by the air-cooling and/or drying device, and/or moisture-condensing device 2 arranged in the calender, in which cooling- agent circulation, e.g., cooling-water circulation, takes place. In order to precipitate water evaporating in a 10 calender, about 50 dm ³ /s of cooling water must be supplied, if ΔT (the temperature increase) is 10 ⁰ C. This is possible, because in practice water is generally abundantly available. At any rate, it is advantageous if the temperature of the cooling unit is transferred to the cooling water in order to preserve the temperature of the cooling water.

A critical criterion is the efficiency of the condensing surface, especially its heat transfer coefficient, which is reduced by the condensing water layer (or film). A typical calender

air mass (50 ⁰ C, 50% RH) condenses at a temperature of about 35-45 ⁰ C. Cooling the condensing surface to about 20 °C, produces a heat-transfer coefficient of about 10-15 kW/m ² K on the surface, whereby a condensing surface area of about 10-20 m ² is sufficient in order to obtain the needed condensation effect. Making the condensation removal more efficient allows for a smaller surface area.

Reference is made to Fig..4, showing a regulating element 72, 73, 81 according to the present invention. Typically a regulating element according to the present invention contains a valve 73, such as a compensation [or: makeup-air]/blow valve, or a suction valve, and a nozzle connected with the valve 81, as well as a duct channel 72 connected with the valve.

According to the basic idea of the invention, the regulating element 72, 73, 81 is moveable, or the place of the regulating element may be moved, at least in the direction of travel of the fibrous web (downstream direction). Thus, the regulating element may be moved in the direction of the support frame (not shown) of the roll cluster 31, 32, e.g., along the support structure (pillar] 70.

Most often the roll cluster 31, 32 is essentially a vertical roll cluster, as shown in the figure, or a tilted roll cluster, or a roll cluster, whereby the moving line winds itself through the rotational axes of the rolls. Another possible direction of travel of the regulating element affecting the treatment of the fibrous web W is moving the regulating element in the direction of travel of the machine line, or generally following the travel of the fibrous web; as an example may be mentioned a soft calender.

The present invention makes it possible to adjust the - the regulating element's 72, 73, 81

- place,

- position, as well as

- the direction or force of the blowing or suction; or i. the place, ii. position

- of the duct channel 72, connected with the regulating element, as well as iii. the position obtained by the blow or suction.

It should be mentioned in this context that various moistening devices, steam boxes and cleaning devices may be used as a regulating element 72, 73, 81, each having their own separate and combined essential effect upon the moisture of the fibrous web and/or its surrounding air.

An advantageous regulating element affecting the moisture of the fibrous web and/or its surrounding air is a drying unit 15, 16, which may also be, as explained above, an air- condensing device or an air-conditioning system. The regulating element of the embodiment shown in Fig. 4 is arranged either at the lower end or lower part of the support structure. Thus, the air being dried or whose moisture is adjusted may be directed through the support structure on [top of] the regulating elements 72, 73, 81, which are movable along the support structure. Thus, a blow nozzle 81, for example, may be in connection with the regulating element. It should be noted that the air directed on to the regulating element may also come from somewhere other than a drying unit. Such an option, considered to be advantageous, is to take the air to the regulating element directly from the vicinity of the calender 21, 22, the air-conditioning system, or the air- condensing device.

Such a moveable regulating element allows the following:

- in order to run various paper grades, or when using different travel speeds, the position of the water-moistening device relative to the thermo-roll nip is changeable, as well as mountable, at completely different points in the roll cluster system, e.g., in the thermo-roll space;

- to take into account into account various run situations, the position of the steam box is changeable;

- The position of the regulating element may be changed, e.g., by swing machines, provided with so-called variable run modes, e.g., matte-nip run / partial nip run, in order to run various paper grades,

- If necessary to enable operation, a moveable cleaning device is needed on all rolls 31 , 32 of the roll system 21, 22, whereby, advantageously, the amount of cleaning devices is minimized as there is no need to install a device for each roll.

Reference is furthermore made to Fig. 4, illustrating a solution for a regulating element 72, 73, 81 in order to obtain mobility. The regulating elements are connected with a moveable service platform 61, a maintenance bridge 71, a hoist 74 or other similar means on the support structure in order to enable mobility on the roll system 21, 22. The service platform, hoist, etc., are designed such that they may be moved to a desired position relative to the rolls 31, 32 of the roll system. The support structure 70 also has the necessary motion devices in order to move the regulating element in the roll-system direction. The most typical directions of motion for the operating position and in the operation position are:

- The vertical direction according to Fig. 4; - The lateral direction; and

- The direction of the angle of tilt of the relevant roll system to be tilted.

The arrangement according to Fig. 4 enables positional adjustment of the regulating elements 72, 73, 81, such as the blow valve, makeup-air valve, suction-air valve 73 and their duct system 72 or nozzle 81, and/or adjustment of the blow/suction direction, whereby the position and/or direction of the regulating elements needed for ventilating the environment of the fibrous web W in the calender 21, 22, and/or the direction of the exhaust suction and blow direction may be adjusted if necessary. Moreover, it becomes possible to direct the exhaust suction and blowing onto the desired area of the calender.

The duct system 72, e.g., an air-conditioning duct system, connected with the regulating element 72, 73, 81 according to the invention, or forming a such duct system, is placed on a connection for a service platform 61, service bridge 71, hoist 74 or other similar means, whose position may be moved, and whose position, e.g., directional height position, may be changed during calendering, so that the desired position of the duct system connected with the regulating element, preferably a blow valve or suction air valve or similar valve, may be obtained.

Reference is made to Fig. 5, showing a third embodiment considered advantageous for air-conditioning the calender environment, especially in connection with a multi-roll calender. In this embodiment, the position of the regulating elements 72, 73, 81 needed to ventilate calender environment in the calender 21, 22, i.e., at least the fibrous-web W environment, and/or the direction of blowing and/or suction produced by the regulating element is/are adjustable. Thus, it is advantageous that the blowing and/or suction may be controlled [or: directed] by the regulating element. Taking into special consideration the object of the present invention, it is advantageous that the blowing and/or suction may be controlled [or: directed] onto the condensing area for the air containing moisture.

In a third example of the present invention according to Fig. 5, the air-conditioning duct system 72 is placed in a positionally adjustable way on a connection for the service bridge 71, the hoist, or other similar position-adjustable means. In order to adjust the controlled air-conditioning, ventilation, blowing, or suction effect in the lateral direction, the duct system connected with the regulating element 72, 73, 81 includes a length- adjustable nozzle part 81, or the regulating element itself may be of the length-adjustable or telescope type. According to the invention, the support structure for the service platform (61, see Fig. 4), the service bridge 71, or the hoist (74, see Fig. 4) may be arranged to be moveable along rail means arranged on the machine-room floor of the fibrous-web machine.

For the motion of the service bridge 71, also while running the calender, so that the desired height position of the regulating elements and/or the height position of their duct system may be obtained in order to implement the desired and preferably controlled air- conditioning, ventilation, blow or suction effect, the supply channel 80 connected with the duct system 72 is of the length-adjustable, e.g., so-called telescope type. The supply channel may be arranged, e.g., on the inside of the hydraulic and/or pneumatic-force cylinder moving the service bridge, so that the supply channel will be connected with the duct system 72 at the top.

It is preferably according to the invention that the duct system 21, 22 includes a telescope part 80 or other similar flow channel 80, whose length may be changed in the vertical direction or the direction of the web W travel. An advantageous regulating element affecting the moisture of the fibrous web and/or the surrounding air is the drying unit 15, 16, which may also be an air-condensing device or an air-conditioning system. The regulating element in the example shown in Fig. is arranged either on the lower end or lower part of the support structure 70. Thus the air being dried or whose moisture is adjusted may be directed into the length-adjustable flow channel.

It should generally also be stated with respect to the invention that the direction and force of the suction/blowing often need to be adjustable. Thus, it is also advantageous, especially in order to ensure an even treatment of the fibrous web W in the CD (cross) direction that the blowing and/or suction related to the ventilation and/or air-conditioning may occur in more than one position in the CD direction, so that there will be more than one regulating element 72, 73, 81 affecting the air surrounding the fibrous web.

Alternatively, the influencing of the fibrous web may occur in the CD direction through a slotted nozzle.

Moreover, the air surrounding the fibrous web W may be influenced and the fibrous-web processing in the calender 21, 22 controlled such that the regulating elements 72, 73 81 may be guided in the CD direction, independently of one another. If necessary., the valves provided in the regulating elements may also be moved in the CD direction.

Fig. 6 shows the processing of the fibrous web by means of the metal belt 5. Such a metal belt may be used essentially in all fibrous-web units, e.g., a press unit, drying unit, coating unit, and calender 21, 22. The metal belt processing the fibrous web in the example shown in Fig. 6 travels to the supporting thermo-roll 31 and the guide roll 6, of which there are four in the example shown in Fig. 6. Using the guide rolls, the tension of the metal belt may be adjusted, and the metal belt heated and cooled. The thermo-roll may be in contact with the opposing roll 32 in order to form a thermo-roll nip, whereby the metal belt and the fibrous web W to be processed travel through the thermo-roll nip. The drying unit of the example shown in Fig. 6 is arranged on the lower part of the thermo-roll. Thus, the moist air is directed, for example, straight from the environment of the thermo-roll or roll pair consisting of the thermo-roll and its opposing roll, and/or from the surrounding air, e.g., the air of the machine hall, to the drying unit 15, 16, from where the air being dried is directed to the environment of the thermo-roll 31 or the above- mentioned roll pair.

The invention was described above only by means of an example considered advantageous with respect to the calender. As is obvious to an expert in the field, many modifications, alternatives and solutions producing a functionally equivalent effect are possible within the scope of the inventive idea, which are specified in the attached claims.

Thus, whereas the treatment and calendering of the fibrous web are dependent on many different parameters, among which may be mentioned:

- Line [knife-edge] load in the treatment affecting the nip; Outside temperature affecting the fibrous web;

The temperature, machine speed, moisture, thickness, properties and bulk density of the fibrous web;

- The radius of the rolls in the treatment unit; The flexibility of the soft roll; ^■ and whereas among the mentioned parameters, the most important ones being the line load and the temperature of the roll to be heated up, e.g., the thermo-roll temperature, it is obvious that the applicability of the present invention in terms of its object is not limited to the calender according to the examples considered advantageous and explained above, instead the present invention may be applied generally in various fibrous-web-machine units, where a roll or cylinder contact affects the fibrous web. Moreover, it may be especially mentioned that the regulating element explained above comprising a channel and a valve, as well as a nozzle, achieving the controlled effect, may also be a drying device, steam box and/or a cleaning device, per se, essentially affecting the moisture of the fibrous web and/or its surrounding air.

It needs therefore to be emphasized that the scope of the present invention covers various fibrous-web, roll and/or cylinder contacts, including:

- Various guide-roll contacts in the fibrous web, take-off contacts and spreader-roll contacts; - Pressing contacts, among other things, in the compression unit;

- Drying cylinder contacts in the drier unit and the hood for evaporating and air- conditioning of water vapor;

- Drying-cylinder contacts in the coating unit, and airborne web drying and IR drying.

According to the basic idea of the invention, the surrounding air moisture and temperature of the fibrous web may thus be influenced in fibrous web processing by controlling the surrounding air in a novel and inventive way, as a result of which: Process advantages are obtained;

Improved drivability and operational reliability and cleanliness are obtained; The drying unit, especially condensate removal becomes simpler, large air masses no longer need to be moved over long distances.