FI84739B - Method and arrangement in pressure treatment of a fiber web - Google Patents

Description

84739

The invention relates to a method for a fibrous web compression treatment in which water is removed from the fibrous web and possibly its properties are otherwise controlled.

10

The invention further relates to a device for carrying out the method according to the invention, which comprises a heated cylinder or roll, the outer surface of the jacket of which forms a compression zone with the counter-element, through which the fibrous web to be treated is passed.

15

The removed water is obtained from the paper web by pressing so that the dry matter content of the web is ka = 40-45%. The rest of the water has had to be removed by evaporation, which consumes substantially more energy than the dewatering per unit mass obtained by pressing. It is known to enhance the dewatering by raising the temperature of the web to be pressed and the water therein, e.g. with steam boxes. It has not always been possible to achieve a sufficient increase in dry matter by these means, but a significant part of the so-called even free water which is not hydrogen bonded to the fibrous material has had to be removed from the web by evaporation.

... 25

As the production speeds of paper machines increase, dewatering by nip pressing has become a bottleneck limiting the increase in speed. This is due to the fact that the press nips formed by the pair of rollers are short in area, so that at high speeds the residence time of the web in them remains short. In an attempt to increase the dewatering efficiency by increasing the nip pressure, a certain line pressure is reached at the limit where increasing the nip pressure no longer helps, as the web structure can no longer withstand compression.

Impulse drying or hot pressing methods are also known in the art, for which reference is made, for example, to U.S. Patent No. 4,324,613, according to which a paper web is pressed in a roll nip in which one roll or cylinder is heated to a temperature above 100 ° C by surface heating.

2,84739

In said nip, the surface water of the paper web is made to evaporate and the pressurized steam blows water pressed into the intermediate spaces of the paper fiber into the press felt. The dry matter content achieved with this known compression method is quite good, but the problem is the short nip time of the high speed machine 5, because the compression time of the roll nip is only about 1 ... 3 ms, so that evaporation does not start properly unless the roll temperature is very high 500 ° C). The high temperature of the roll causes problems, especially with respect to the compression fabric and the durability of the rolls.

As can be seen from the above, it is already known to heat the surface of a press roll or a cylinder for the purpose of so-called providing impulse drying or web detachment. One preferred known method of heating a press roll or calender roll is external non-contact inductive eddy current heating.

15

In the pulse drying process, the drainage from the web is almost entirely determined by the temperature and nip time of the hot roll or cylinder. The previously known hot rollers are heated outside the hot press nip, in which case a strong thermal shock has to be applied to the surface of the hot roll and the heat losses to the environment become quite large.

Referring to the prior art of the present invention, reference is also made to U.S. Patent 4,704,191 (Beloit Corp.), which discloses a long nip press in which a pressing force is provided at least in part magnetically such that the long nip shoe has a wide end face against the other shoe or roll and a pressing force or the adjustment of the distribution is effected by magnetic forces. Impulse drying or the active use of a magnetic shoe to substantially raise the temperature of the cylinder surface is not disclosed in this U.S. patent, although naturally the use of a magnetic shoe may result in eddy current losses that may have little heating effect.

It is an object of the present invention to provide solutions to the problems discussed above. The invention has been based on induction heating of a roll surface, which has several inherent advantages, not all of which have previously been effectively utilized.

3,84739

It is a further object of the invention to provide a method and apparatus in which the heating of a press roll surface, especially in connection with pulse drying, can considerably alleviate the thermal shock of the cylinder or roll surface and thus create wider possibilities in the choice of surface material and other construction.

The object of the invention is to provide a method of heating a roll or cylinder surface and a paper web to be pressed against it, in which better heat conduction and lower heat losses can be realized so that the nip time can be shortened and / or the roll temperature can be lowered and / or dewatered more efficient.

In order to achieve the above and later objects, the method of the invention is mainly characterized in that the surface of the cylinder 15 or roll, which partly forms the compression zone, is heated by electromagnetic induction based on eddy currents in a compression zone through which the web is passed in direct contact with said cylinder. in the region of the compression zone, heat is transferred from the induction heated cylinder or roll surface 20 to the fibrous web.

The device according to the invention, in turn, is mainly characterized in that said device comprises a combined heating and pressing shoe supported on a support member, that said combined heating and pressing shoe has a abutment surface for applying a pressing effect to the fibrous web via a strip member or the like, and said shoe in connection with a magnetizing coil or coils, by means of which an induction heating effect based on eddy currents is applied to the outer layer of the pressing element on the fibrous web side, which is an electrically conductive material.

* 84739

The method and device of the invention transfer energy during the nip to the roll, on the principle of electromagnetic induction, from which the energy is immediately transferred as heat to the web, causing the intended evaporation process. Since the invention simultaneously introduces energy to the same location as it is consumed, the thermal shock experienced by the roll is not as strong as with previously known methods. The amount of heat produced by induction and the amount of heat transferred through the surface can be set equal by power control. In addition, the energy profile in the roll produced by induction heating is approximately the same as that produced by the energy leaving the surface of the roll, i.e. the heat is brought where it is consumed. The transverse heating profile can be adjusted by adjusting the distance of the ferrites from the roll or, when the excitation coil is formed of several separate coils, by adjusting their sides separately.

15 The severe thermal shock previously caused to the roll is reduced. The temperature of the roll does not drop during the nip, so that the heat transfer at the end of the nip is more efficient compared to known solutions.

The invention applies eddy current-based magnetic induction heating in connection with a hot cylinder or roll having an outer surface of an electrically conductive material, but not necessarily a ferromagnetic material.

In a preferred embodiment of the invention, the induction heater is integrated into the press shoe nip structures so that heat is generated specifically in the area of the shoe nip, i.e. the heat is produced where it is consumed, i.e. transferred to the affected web.

The integrated heating and pressing shoe of the invention may be either hydrostatic or hydrodynamic, or a combination thereof. When using hydraulic pressure chambers in connection with a shoe, which apply a pressure effect directly to the belt passing over the hot roll, which presses the web against the hot roll casing, it is advantageous to use hydraulic fluid e.g.

5,84739

In the invention, due to the better thermal conductivity, the nip time can be shortened and / or the surface temperature of the roll can be lowered and / or the dewatering can be improved.

In the invention, an electrically conductive collection 5 which is selectable to withstand thermal shocks, mechanical wear and a suitable detachment of the web from the roll surface can be advantageously used as the roll coating.

When applying the invention to pulse drying, the thermal energy is preferably applied to a relatively thin outer jacket surface of the electrically conductive assemblies 10 of the heating cylinder or roll. The heating depth can be obtained by setting the penetration depth based on the thickness of the ceramic jacket and / or the insulation layer below it and / or the frequency of inductive heating so that the thermal energy supplied to the induction device has time to transfer to the web in the nip or nips.

15

The most popular embodiment of the invention is pulse drying, the high energy flow required of which causes a strong rise in temperature in the roll. The present invention reduces roll temperature variation during a cycle. In this way, opportunities are created for a freer choice of material for the roll surface, which in turn facilitates the factory-scale implementation of pulse drying.

According to the invention, an induction heating arrangement can be provided which has good efficiency and the device implementations are made relatively small in size and otherwise advantageous.

Thanks to the invention, heat losses and fire risks can also be significantly reduced than, for example, with infrared heating.

The invention will now be described in detail with reference to some examples of embodiments of the invention shown in the figures of the accompanying drawing, to the details of which the invention is in no way narrowly limited.

35 6 84739

Figure 1 schematically shows an induction heating according to the invention applied to an impulse drying device using a hot cylinder and an associated pressing and magnetic shoe device.

Fig. 1A shows the distribution of the compression pressure in the device according to Fig. 1.

Figure 2 shows a vertical section of a heating-pressing shoe according to the invention. Figure 2 is at the same time section II-II of Figure 3.

10

Figure 3 shows a section III-III in Figure 2.

Fig. 4 schematically shows a compression heating shoe according to the invention from its end face side, i.e. in Fig. 2, seen from above without a hot cylinder.

Figure 5 shows graphically the roll temperatures and heat fluxes as a function of nip time.

Figure 6 shows a schematic cross-section of a preferred jacket structure of a hot cylinder used in connection with the invention.

The hot press or pulse drying apparatus shown in Fig. 1 comprises a relatively large diameter hot cylinder 10 with a drive 10a having a smooth outer surface 10 'consisting of a ferromagnetic material or an electrically conductive ceramic layer or other electrically conductive material.

The basic temperature T0 of the surface 10 'of the cylinder 10 is arranged e.g.

30 T0> 100 ° C when the surface 10 'encounters a web W to be hot-pressed on the surface of the press felt 12, the dry matter content of which is marked KAln. Depending on the placement of the hot pressing device according to the invention in the process, KAin generally varies between KAln - 25 ... 55%.

The device further comprises a press roll 21 arranged before the pressing and magnetic shoe device 30, having a smooth jacket surface 21 'and provided with a drive 21a 7 to 4739. The press roll 21 is placed inside the loop of the conveyor belt 25 and the roll 21 forms a nip N10 with the hot cylinder 10. The web W is introduced directly into the nip N10 under the support of the press felt 12, so that the web W immediately comes against the smooth surface 10 'heated inductively by the shoe device 5 of the cylinder 10. Correspondingly, the compression felt 12 is separated after the second nip N20 from the web W following the smooth surface 10 'of the cylinder 10, from which it is separated as a free pull Wp.

The invention uses a combined pressing and heating shoe device 30, 10 which is shown only schematically in Figure 1 and the structure and operation of which will be described in more detail with reference to Figures 2, 3 and 4. According to Figure 1, the shoe device 30 is placed in connection with a cross beam 30a inside the belt loop 25. The shoe device 30 has cylinders 31 loaded with hydraulic fluid and having pistons 33 which load 15 load shoes 35. The load shoes 35 have compression and lubrication chambers operated by pressurized fluid. The end face 37 of the shoe 35 corresponds to the inner surface of the strip loop 25 and presses the web against the surface 10 'of the roll 10 in the zone indicated by C in Fig. 1A. The length of said zone is e.g. 300-400 mm. Prior to the shoe 35 are spray devices 28 for directing 20 jets of lubricant s onto the inner surface of the strip 25. The heating energy of the shoe device 30 is supplied from the electrical and control devices shown schematically in block 100 in Figures 1 and 2.

According to Fig. 1, a second magnetic shoe device 30 'is placed on the inside of the jacket 21a of the first press roll 21, which applies a heating effect to the web W passing through the nip N10 through the strip 25, specifically in the region of the nip N10. The device 30 'comprises a stationary shaft 30b arranged inside a roll shell 21a, to which a combined pressing and heating shoe 35' is arranged, which may be similar to the shoe 35 of the latter device 30. The sheath 21a of the pressing roll 21 is quite thin and is preferably non-conductive. . The depth of penetration of the heating effect of the shoe 35 'is preferably extended to the surface 10' of the roll 10. The device 30 'is not always needed and can be replaced by deflection compensation devices known per se, which are based on compression sliding shoes acting on the inner surface 21a' of the roll shell 35a. The device 30 'is intended to illustrate and illustrate that the combined heat-press shoe device according to the invention can also be used in connection with roll nips and placed inside a roll shell, although the device 30 is the most preferred and main embodiment of the invention.

A splash water collecting trough 27 is arranged around the loop of the conveyor belt 25. The second press roll 20 is provided with a smooth surface 20 'and a drive 20a, and behind it is a lubricant collecting trough 24 from which the lubricant is fed by a recirculation device.

The second press roll 20 forms a nip N20 with the hot cylinder 10. after which the web W follows the smooth surface 10 'of the cylinder 10, from which it is separated by a guide roll 13 provided with a pull Wp and transferred to the support of the drying fabric 15 guided by the guide roll 14. The fabric 15 takes the web W to the drying section, where the dewatering is continued by evaporation.

15

The dry matter content of the web W after the hot pressing machine is denoted KAout. In general, this dry matter content KAout - 50 ... 75%.

The paper web W is pressed against the surface 10 'of the hot (T0> 100 ° C) cylinder 10 by means of a relatively low pressure (p ^ long nip-20 press shoe 35) via a belt 25 and a press felt 12, and the surface of the paper web W against the surface is heated e.g. The temperature of said surface 10 'when it comes into contact with the web W is in the range T0 to 175-550 ° C.

25

Shoe 35 is hydrostatic, hydrodynamic, or a combination thereof. After the heating and long nip pressing step C, the pressure on the paper web W decreases to a level p0 determined by the tension of the belt 25 in the zone D, and the evaporation of water from the paper web W is enhanced by the pressure drop p! -> p „30 thanks. Pressure pQ - T / R, where the T-belt 25 is the tension tension and the radius of the R-cylinder 10. After zone D, an intensive pressing step takes place in the nip N20, in which the paper web W is pressed with a high pressure between the cylinder 10 or the corresponding roll and the pressing roll 20. This step is shown in Figure 1A by E and the maximum compression pressure is then preferably praax2 to 8 MPa. In the pressing step E, water vapor is blown through the paper web W, causing the water 9 84739 in the interstices of the fibers to be blown out and thus an enhanced compression result and an even higher dry matter content KAout.

The so-called conveyor belt 25 can also be used. an elastic belt by means of which the zones A and E of the nips N10 and N20 of the roll-5 and at the same time their pressing time can be extended and the pressing pulse increased. If necessary, a separate elastic band can also be used, which is passed between the conveyor belt 25 and the felt 12. Since water cannot be pressed from the press felt 12 onto the hollow surfaces of the rollers, the hollow surface can be made on the belt 25 if necessary.

10

In step A shown in Fig. 1A, in which a peak compression pressure pmax1 = 4 MPa is applied to the nip N10, it is a question of a first hot compression step. Stage B is the pressure drop step, step C is the second preheat-compression step and step D is the pressure drop and vapor generation step and step E (peak pressure pmax2 ~ 8 MPa) is the actual (intensive) compression and blow-through step.

In the middle row (L) below the zone markings A-E, Fig. 1A shows examples of the preferred lengths (mm) of said zones and the corresponding residence times (ms) in the bottom row (t) when using a machine speed v to 20 m / s.

A preferred structural example of a heating and pressing shoe according to the invention will now be described with reference to Figures 2, 3 and 4.

25

According to Figure 2, the shoe device 30 is positioned to act against the cylinder 10 to be heated. The cylinder 10 has a jacket 1, at least the outer layer of which is electrically conductive, e.g. of ceramic material or ferromagnetic material. The device 30 comprises a pressing shoe 35, which preferably extends 30 over the entire width of the web W. The shoe 35 is connected to a series of load pistons 33 fitted to the load cylinders 31. A pressure medium is supplied to the load cylinders 31 via pipes 32 from a pressure source shown schematically in block 60 in Figure 2. A narrow passage 34 is passed through the shoe 35 from the pressure space of the cylinders 31. The channel 35 34 opens at the central end face 37 of the shoe 35 into pressure spaces 36 bounded by the end faces 37 10 Θ 4739 at both the front and rear edges of the shoe 35 and the end faces 37a, 37b at the edges of the shoe. By applying different pressures to the different cylinders 31, the pressure distribution in the axial direction of the roll 10 can be adjusted. Some alternative constructions which are used in connection with the invention and which relate specifically to a hydrostatic and / or hydrodynamic compression shoe are disclosed in the applicant's FI patent applications Nos. 860644 and 861612.

According to Figures 2, 3 and 4, ferrite parts 10 are formed as magnetic shoe cores 38 for magnetic shoe devices in connection with the pressure spaces 36, which are formed by parts 38c and fixed inner parts 38b and adjustable edge parts 38a opposite the bottom planes of the pressure spaces. The air gaps V of the parts 38a with respect to the outer surface 10 'of the roll shell 1 are arranged to be adjustable. Attached to the upper surface of the ferrite portions 38c is an insulating body 41, on top of which is, for example, a magnetic coil 40 of copper with one or more turns. The coil 40 preferably has only one turn, so that the coil consists of two copper strips, the other ends of which are connected to each other by a conductor 52 and a capacitor C (Fig. 4). The opposite ends of the coil strips are connected by conductors 52 to the secondary windings 51T of the transformer 51. The coil 40,52,0 is fed through a transformer 51 from an AC power source 50 as shown in Figure 4.

According to Figures 2 and 3, the ferrite parts 38a of the magnetic core are arranged to be adjustable so that their air gap V with respect to the roll surface 10 'is adjustable. The magnetic core 38 is comprised of a plurality of parallel core portions 25 each individually adjusted by a stepper motor 42. The stepper motors 42 are secured to brackets 35 by brackets 43. The stepper motors 42 have shafts using an adjusting nut or mandrel attached to adjustable ferrite members 38a at 44. By adjusting the air gaps V by the stepper motors 42, the distribution of the magnetic flux density in the axial direction 30 of the roll 10 can be controlled, on the basis of which the inductive heating effect described in more detail below occurs in at least a part of the roll 10.

With respect to the electrotechnical background of the invention, the following is stated. When a variable magnetic field is provided in the electrically conductive outer layer of the roll 10 35 or the cylinder, eddy current and 11 84739 hysteresis losses are known to occur in its material and the material heats up. The power of eddy currents (P) depends on the strength of the magnetic field (B) and the frequency of change of the magnetic field (f) as follows: 5 P ~ B2 f2 (1)

The alternating magnetic field of the outer layer of the roll 10 is closed through the end face of the ferrite portions 38a, 38b of the cores 38 between the air gaps V. This magnetic field of the mag-10 induces eddy currents in the outer layer of the roll 10 shell, which generate heat due to the resistance of the layer. Distribution of eddy currents induced in the outer layer in the radial direction x of the roll 10 follows the law 15 Ix = I0e - * / Ä (2) where

Ix is the current density at depth x from the roll jacket surface 10 ', 20 I0 is the current density at the jacket 10 surface 10' and S is the penetration depth. The penetration depth is defined as the depth at which the current density has decreased to 1 / e of the surface current density I0. 25 The penetration depth gives the expression δ = 1 I I0l £. läT (3) 2π \ ίμ Qs p is the resistivity of the material of the outer layer 10 of the roll, f is the frequency of the excitation current and μ is the relative permeability of the ceramic material of the outer layer.

i2 84739

Expression (3) shows that as the frequency increases, the penetration depth decreases.

The invention generally uses heating powers of the order of 1.5 W / m.

As is known, the smaller the air gaps V, the larger part of the electrical power supplied to the device through the coil 40 is transferred to the outer layer of the roll 10 to be heated.

The purpose of the graphical representation of Fig. 5 is to illustrate the relative temperature T of the roll surface realized in the combined pressing and heating nip according to the invention 10 and the heat flow transferred to the web W to be treated in the region of the nip. As is known in the pulse drying process, the dewatering is almost entirely determined by the roll temperature T and the nip time t. Thus, the dewatering Q - q (T, t) can generally be written. In Fig. 5, the curves A refer to previously known methods in which the heat flux from the roll surface to the web decreases sharply (curve shown in broken lines). Correspondingly, the temperature of the roll surface decreases in previously known methods (dashed line and two-point curve) when heat is introduced into the roll outside the nip. The mode of action 20 of the invention is illustrated in Figure 5 by curves B. The roll surface temperature T remains substantially constant over the entire nip region (curve shown in broken lines). The heat flux from the roll surface 10 'to the web W as a function of the nip time also decreases very little (curve shown by dotted lines). Thus, thanks to the invention, when the roll surface 10 'is heated during compression, the heat transfer 25 is considerably more efficient (curves B in Figure 5) at the end of the compression step than when the roll is heated outside the nip as is already known. Thanks to better heat conduction, the nip time can be shortened and / or the roll temperature can be lowered and / or dewatering can be improved.

Fig. 6 shows a structural example of the jacket of the hot roll 10. The sheath consists of an inner sheath 1 of construction metal, which gives the roll its necessary strength. An insulating layer 2 is made on the outer surface of the sheath 1, which is, for example, electrical and heat insulating collections. An outer layer 3 is formed on the outer surface of the insulating layer 2, which forms a smooth outer surface 10 'of the roll 10. The outer layer 3 is an electrically conductive composite ceramic, e.g. boride ceramics, based on diborides of titanium and zirconium 13 84739. The resistivity of the ceramic material of layer 3 is e.g. in the range 2-10 Ω cm x 10-5. The thickness of the outer layer 3 is e.g. in the range 0.1-2 mm, the thickness of the insulating layer 2 is e.g. in the range 3-10 mm. The hardness of the outer layer 3 is e.g. in the range 800-1000 HV and the bending strength e.g. in the range 5,300-900 N / mm2.

The following claims set forth within the scope of the inventive idea defined by the invention may vary and differ from those set forth above by way of example only.

10

Claims (14)

A method for pressing treatment of a fibrous web (W), wherein water is removed from the fibrous web (W) and possibly its properties are otherwise controlled by a nip pressing step, in which the fibrous web (W) is passed to a pressing zone (A, C, E) formed by opposite pressing members (10,35,20,21). ), in the region of the pressing zone (A, C, E) of which a heating effect is applied to the fibrous web (W), characterized in that the surface (10 ') of the cylinder or roll (10), which partly forms the pressing zone 10 (A, C, E), is heated by electromagnetic induction based on eddy currents in a compression zone (A, C, E) through which the web is passed in direct contact with said cylinder or roll surface (10 ') so that in the same region of the compression zone (A, C, E) heat is transferred from the induction heated cylinder or roll surface (10 ') to the fibrous web (W). 15 A method according to claim 1, characterized in that the method is applied in pulse drying to raise the temperature level of the surface of the fibrous web (W) in the range T to 100-160 ° C. 20 A method according to claim 1, characterized in that the method is applied in a roll nip and / or shoe nip pressing step of the fibrous web (W), in which a substantial amount of water is removed from the web (W) by pressing and said viscosity also reduces the viscosity of water in the fibrous web (W). and modifying the elastic properties of the fibrous web (W) so that dewatering is enhanced in said nip or nips. Method according to one of Claims 1 to 3, characterized in that the method uses a cylinder or roll surface (10 ') in direct contact with the fibrous web (W) to be treated and in that the penetration depth of said induction heating effect in the radial direction of the cylinder or roll (10) is limited. or by selecting the structure of the outer layer (3) of the roll (10) (Fig. 6) and / or the electric frequency (f) of the induction heating. 15 84739 Method according to one of Claims 1 to 4, characterized in that the method uses a combined induction heating and pressing shoe (35), in which case ila-adjustable ferrite cores (38) and hydrostatically and / or hydrodynamically loaded pressure zones are preferably used and with which shoe (35) applies the heating and pressing effect through the impermeable belt (25) (Figs. 2, 3 and 2). Method according to one of Claims 1 to 5, characterized in that in the method the distribution of the heating effect in the axial direction of the roll or cylinder (10) to be heated is controlled by the air gap of the ferrite core (38), the power to be magnetized and / or its frequency. Apparatus for carrying out the method according to any one of claims 1 to 6, comprising a heated cylinder or roll (10; 21), the outer surface (10 ') of the jacket (1) forming a compression zone (A, C, E) with the counter-element, through which a conductive fibrous web (W) to be treated, characterized in that said device comprises a combined heating and pressing shoe (35; 35 ') supported on a support member (30a; 30b) and said combined heating and pressing shoe (35; 35') ) has a abutment surface for applying a compressive effect to the fibrous web (W) via a strip member (25) or the like, and that said shoe (35; 35 ') is provided with a magnetizing coil (40) or coils for applying an eddy current induction coil. heating effect on the ____ outer layer of the compression element in (10) on the fibrous web (W) side, which is an electrically conductive material. Device according to claim 7, characterized in that the device has an elongate pressing shoe (35) in the transverse direction of the fibrous web (W), which forms a pressing zone (C) with said opposing roll or cylinder (10) and said pressing zone (C). ) is passed through an impermeable compression belt (25) and a compression fabric (12) or fabrics (12) such that in connection with said compression shoe (35) there is a magnetizing coil (40) or 5 coils and a magnetic core (38) of magnetically highly conductive material, or - cores that the air gaps (V) of said core or core portions (38a) with the outer surface (10 ') of the opposite roll are arranged to be adjustable for adjusting the transverse distribution of the heating effect (Figures 2,3, and 4). 10 Device according to claim 8, characterized in that said pressing shoe (35) is provided with one or more load pistons (35) arranged in connection with cylinders (31) to be loaded with a pressure medium, said counter-roller or cylinder of said pressing shoe (35) The end face (10) has pressure-loaded spaces (36) which will be bounded on the outside by a compression belt (25), 20 and said spaces (36) have end faces (37) which, together with said compression strip (25), define pressure fluid spaces loading the nip zone ( C), 25 that an electromagnetic coil (40) or coils to which alternating current is supplied from an electrical source (50) are arranged in said spaces (36). Device according to claim 8 or 9, characterized in that said magnetic cores (38) consist of ferrite core portions (38a, 38b, 38c) arranged in said pressurized fluid spaces (36), at least one of the portions of which form a counter-element of the air gap (V). with the outer surface (10 ') is arranged to be adjusted in position by the actuators (42) for adjusting the level and / or distribution of the heating effect. 35 17 84739 Device according to any one of claims 7 to 10, characterized in that said counter roll or cylinder (10), the outer sheath of which is subjected to a heating effect, comprises an electrically conductive outer layer (3) having a non-conductive insulating layer (2) inside. a cylinder or roll body shell (11) of structural metal which imparts to the cylinder (10) or roll the main strength properties (Figure 6). Device according to claim 11, characterized in that said outer layer (3) is formed of an electrically conductive ceramic. Device according to claim 12, characterized in that said electrically conductive ceramic is boride ceramics, preferably based on diborides of titanium and zirconium. 15 Device according to claim 12 or 13, characterized in that the thickness of said electrically conductive ceramic layer (3) is in the range of 0.1 to 2 mm, and / or that the resistivity of said electrically conductive ceramic is in the range of 1 to 15 Ω cm x 10-5. 20 ie 84739