FI75009B - FOERFARANDE OCH ANORDNING FOER KONTAKTLOES TORKNING AV EN PAPPERSBANA ELLER MOTSVARANDE. - Google Patents

Description

> 75009 1 Method and apparatus for non-experimental drying of a paper web or the like Förfarande och anordnlng förcontlös torknlng av en papperebana eller motsvarande 5

The invention relates to a method for non-experimental drying of a paper or board web or other similar continuous web, which method uses both infrared radiation and drying air jets to support the web passing through the dryer at the same time without contact. , in which the web is supported and air-dried.

The invention further relates to an apparatus for carrying out the method of the invention, comprising an infrared drying unit and a toy drying unit or fluidized bed drying units, the infra-drying unit comprising an infrared beam; 20 a series of liquids and an associated infra-processing space through which the web to be dried can be guided, each fluid-drying unit or units comprising a housing part on which a nozzle box or boxes • fitted with nozzle parts through which the drying web is applied The present invention relates to the drying of a paper web, paper web or the like. The present invention relates to the drying of a paper web, paperboard web or other web to be dried, and to air drying units, in addition to which the air drying unit and the fluid drying unit are both structurally and functionally integrated. A typical application of the invention is the drying of a paper web in connection with its coating or surface sizing.

35 It is known from the paper webs to be coated either with separate coating machines or on-machine devices integrated with paper machines or with surface gluing devices operating in the paper machine conveying section 75009 1 so that the web to be coated is A typical embodiment of the present invention is the intermediate dryer 5 after the coating bed just mentioned, to which, however, the invention is not limited.

It is already known that the so-called fluidized bed dryers for non-contact drying of paper web, paperboard or the like. The toy dryer is used, for example, in a paper coating device after the roller or brush coater 10 to non-contact to support and dry the wet web from the coating pan. Various drying and support air blowing nozzles and their arrangements are used in fluidized bed cultivators. Said blow nozzles can be divided into two groups, namely overpressure or float nozzles and vacuum or foil nozzles, both of which can be applied in the dryer and method according to the invention.

The previously known most commonly used toy rides are based exclusively on air blowing. For this reason in part, the fluidized bed dryer becomes quite space consuming, because the working distance 20 of the fluidized bed dryer must be relatively long in order to obtain a sufficiently high drying power. In part, these disadvantages are due to the fact that the penetration depth of the drying remains relatively small in air cultivation.

Various dilators based on the effect of radiation, in particular infrared radiation, are already known. The use of infrared radiation has the advantage that the radiation has a relatively large penetration depth, which increases as the wavelength decreases. The use of infrared scanning in paper pulp drying has been hampered by e.g. fire hazard, as the temperatures of the infrared radiators become quite high, e.g. 2000 ° C, in order to achieve sufficiently short-wave drying radiation.

With regard to the state of the art, reference is made to patent application publication DE OS No. 2351280, which discloses a certain type of combination of a fluidized bed dryer and an infrared dryer operating with an overpressure nozzle. Em. patent application discloses a single-sided fluidized bed dryer comprising successive spaced nozzle boxes. At the edges of these boxes there are nozzle slots through which air jets 75009 1 are directed specifically perpendicularly to the ralna 75009 1, which, when they meet the ralna, turn outwards at the nozzle plate. Infrared radiators are arranged between said nozzles, which fill the nozzle gap. To the applicant's knowledge, the above-mentioned dryer has not received at least more extensive use, which is probably due to the fact that the nozzle structure has not been successful, neither structurally nor energy-efficiently, preferably in combining air and regulated drying. In addition, the structure is one-sided and takes up a relatively large space in the direction of travel if it is desired to achieve sufficiently high drying efficiencies, e.g. in paper finishing plants.

10

Particular problems with infrared drying have been strong dust formation and high humidity.

Electric infra-dryers, when used alone or exclusively, are also economically disadvantageous due to the relatively high cost of electrical energy compared to, for example, natural gas.

Separate infrared dryers have been used in paper coating stations, including on-machine coating stations, the drying of which is based on 20 radiation effects alone. However, these infrared dryers have not achieved sufficiently good controllability of paper quality and evaporation.

In addition, the drying process becomes highly dependent on the functionality of the infrared dryer.

The object of the present invention is to solve the above-mentioned problems.

It is a particular object of the present invention to develop a new application of an infrared dryer in which, in particular, the air technology is better solved than before.

It is a further object of the invention to provide a method and apparatus by which the overall control of the coating of the paper web can be improved.

It is also a partial object of the invention to provide a new application of an infrared cultivator so that an even cheaper costing concept can be implemented in terms of both investment and operating costs. To achieve this object, the invention aims at a higher drying power, a smaller equipment size and a lower heat and humidity load in the data center.

It is a particular object of the invention to provide an infrared dryer application that can be used to control the final moisture profile of a web produced by a paper machine.

In order to achieve the above and later objects, the method of the invention is mainly characterized in that in the method the moving web is first introduced into an infrared drying gap, in which the web is subjected to a substantially higher average which, after heating in the infrared unit, is led to the replacement air and / or drying air of the fluidized bed drying unit or units following the infrared unit.

20

The drying device according to the invention, in turn, is mainly characterized in that the infrared drying unit has air and nozzle devices through which air flows to the processing interval of the infra unit and / or to the heating parts of the infra unit are passed downstream of the next fluid drying unit or units. as drying.

With the help of the invention, an even more advantageous drying concept can be implemented, in which both investment and operating costs have been taken into account.

30

Thanks to the invention, an even higher cooling power, a lower heat and humidity load in the data center are achieved and savings are made in the lifting and auxiliary device of the infrared dryer. On the basis of the measurements made by the applicant, the drying test runs and the theoretical examinations, it has been found that the solution of the invention is considerably better both from the point of view of flotation technology and the quality of the paper web than the previously known conveyor arrangement,

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75009 1 where the infrared angle and the fluidized bed dryer are separate independent units.

The method and device according to the invention are particularly well suited for adjusting the on-machine dryer after the coating or surface sizing device and, if necessary, also for adjusting the final moisture profile of the paper web.

In the invention, it is not necessary to build an open hood above the dryer, as in previously known devices, because in the infra-fluid combination 10 of the invention, only the target column is sufficient, because the fluid outlet duct system provides sufficient ventilation.

When natural gas or a similar fuel is used to heat the drying air of a fluidized unit or units, the operating costs of the method and device applying the invention per unit of evaporated water are considerably more advantageous compared to a dryer using only electric heating. This advantage is based on the fact that in the invention the energy transferred to the electroplated paper web becomes efficiently utilized in the toy transport unit or units following the infra unit.

20

The invention will now be described in detail with reference to the prior art of the invention shown in the figures of the accompanying drawings and to some preferred embodiments of the invention.

Figure A shows a lay-out of a prior art paper machine on-machine coating dryer.

Fig. 1 shows, in a manner similar to Fig. A, a sowing method and a sowing-out view according to the present invention.

30

Figure 2 shows a side view of an infrared fluidized bed unit according to the invention.

Figure 2A shows a section A-A in Figure 2.

Figure 2B shows a section B-B in Figure 2.

Fig. 2C shows a double-sided blown overpressure nozzle unit applicable to a fluidized bed dryer according to the invention.

Fig. 2D shows an alternative to the nozzle of Fig. 2C, namely a one-sided blowing vacuum coanda nozzle unit.

Figure 3 illustrates the method according to the invention in the form of an air flow diagram.

Figure 4A shows the evaporation power of a previously known two separate infra units as a function of time.

Fig. 4B shows, in a manner similar to Fig. 4A, the evaporation efficiency of the infrared fluid dryer according to the invention shown in Fig. 1 as a function of time.

Figure A shows a previously known paper finishing and coating station located in the drying section of a paper machine using a prior art drying arrangement. According to Fig. A, the paper web W is introduced over the cylinders 13 of a normal multi-cylinder dryer 10 placed inside the hood 12. The drying wire above the drying section 10 is indicated by reference numeral 11. After the multi-cylinder dryer 10, there are following measuring beams 13A arranged across the web W, in connection with which measuring sensors known per se, such as web moisture and basis weight measuring sensors. After the measuring beam 13, an intermediate press formed by the rollers 14A and 14B follows, after which the web W is guided by the guide rollers 15 to a coating saw 20A known per se. The coating station 20A comprises a coating unit followed by an infrared converter 25 and a separate fluidized bed dryer 26.

The vertical beams of the body of the coating station 20A are denoted by reference numerals 21a 30 and the horizontal beams by reference numeral 21b. After the coating unit 22, the web W, guided by the guide roller 23, moves to the processing interval 25V of the separate infrared conveyor 25. In said processing space 25V, the dried web W is passed in considerably long tensions over the cylinder 23A to the processing space 26V of the fluidized bed dryer 26, where the web V? is non-contactally supported and at the same time 35 is dried by means of air jets discharged from the nozzles (not shown) of the fluidized bed dryer 26.

Il 7 75009 1 After the fluidized bed dryer 26, the web W is transferred, under the guidance of the guide rollers 27, to a post-dryer 30, the first cylinder 33a of which is without felt. The post-dryer 30 is located inside the hood 32 and its upper felt, guided by the guide rollers 34, is indicated by reference numeral 31. The post-dryer 5 has, for example, only one cylinder group with, for example, four drying cylinders 33a and 33. After the post-dryer 30 a fully dried and coated web W is applied to a winding bed (not shown).

In connection with Fig. A, a previously known coating station 20A has been described in some detail above. Later, the operation and efficiency of the method and apparatus of the present invention are compared to the sowing method and apparatus of Fig. A.

Figure 1 shows the same coating and drying process as Figure 15A, except that the coating station 20A shown in Figure A has been replaced by the coating station 20 of the invention. It is conceivable that the coating station 20 shown in Figure A has been modernized by providing its coating station 20 with a new is located in connection with the body portion 21a and 21b of the previous coating station 20A. In these 20 modernizations, the multi-cylinder dryer 10 and the post-dryer 30 have remained intact. It should be emphasized, however, that the dryer 40 of the invention is suitable for many other applications than the application and position shown in Figure 1.

The coating station 20 shown in Fig. 1 consists of a known coating station 22 and an infrared fluidized bed dryer 40 according to the invention and a separate conventional fluidized bed dryer 90 thereafter. The web W extends upwards vertically through the infrared fluidized bed 40 treatment gap 27V -30 in direct flow to the vertical processing interval 90V of the fluidized bed dryer 90 and down there. From the treatment interval 90V, the web W is further guided by the guide rollers 27 to the first drying cylinder 33a and in a known manner further through the post-dryer 30.

A more detailed structure of the infrared fluid dryer 40 according to the invention will be apparent from the accompanying Figures 2,2A, 2B, 2C and 2D. The infrared fluid dryer 40 comprises an infra-conveying unit 50, through the processing interval of which the web W is passed from non-contact 75009 1 and at the same time is dried by infrared radiation R. the nozzle box 5 82B below. The upper nozzle box 82A has a plurality of evenly spaced H nozzles 85a and the lower 82B has a nozzle 85b nozzle 85b evenly spaced so as to form a processing gap 80V through which the web W to be dried and supported passes gently and substantially sinusoidally and profitable hot air closures.

As can be seen from Figures 2 and 3, the invention has an infrared drying unit 50 and a fluidized bed drying unit 80 Integrated as a new drying unit and structural! that, from the point of view of the drying process, mainly taking into account the drying energy technical aspects and the optimal drying event and export of the web. This new integration of drying and air technology is an essential core of the invention.

In the infrared toy carriage 40 according to the invention, the cooling air is blown through the nozzles 55A and 55B as a replacement air 80 to the fluidized bed drying unit 80 and / or 90 as an infrared key 50. In the invention, the leakage air entering the fluidized bed drying unit 80 and the hot cooling air energy coming from the air dryer 50 can be efficiently utilized. The combined infrared toy dryer 40 of the invention allows for a strong peak of the energy of energy on the web 25 immediately after the coating operation and at the beginning of the wetting process (Figure 4, to which we return later).

Details of the construction and operation of the Infra-fluidized bed dryer 40 will now be described with reference to Figs. 2,2A, 2B, 2C, 2D, 3 and 4. In the invention 30, it is essential that the infra-drying unit 50 is located in the direction of travel of the web W to be dried before the fluid-drying unit 80. The infrared drying unit 50 has an upper housing part 5IA and a lower housing part 5IB. These housing parts 51A and 5IB delimit on the front side the guitar part G into which the web is introduced. From the kit part G, an air-sealed inlet nozzle and an infrared treatment interval of the web 35 w begin, in which the web W is supported and stabilized by air jets F and F and at the same time heated and dried by infrared control.

A D

lyy R.

Il 75009 1 The infrastructure unit 50 comprises an upper housing part 54A and a lower housing part 54B. Air pipes 53A and 53B enter said housing parts. The upper housing 54A has a series of infrared radiators 60 with a reflective surface 62 inside the thermal insulator 61. The opposite side 5 of the treatment gap has a reflective surface 63 on the thermal insulator 64 which reflects the infrared radiation R passing through the web W back to the web W. The housings 51A in connection with the inlet rail G to the supply air duct 55A and below, respectively, the housings 51B and 54B delimit the lower supply air duct 55B, from which air is introduced through the tubes 52A and 52B from the air inside the housing 10IA 5A and 51B by the supply air blowers F and F, A ij supporting and stabilizing the wind mentioned interval. In the infra-treatment interval, the air seals F1 and Fg are heated and this heat is recovered by the arrangements shown in Figures 2A and 3, which will be returned later.

15

It can be seen from Fig. 2A, which is a section AA in Fig. 1, that the air introduced through the duct 104 (Fig. 3) of the fan 103 is blown as flows through the tube 52A and 53A to the housing parts 51A.54A above the infra unit 50. for escort blowing F ^. As can be seen from Figures 2 and 2A, the inlet flows FBin »of the pipes 52B and 53B connected to the channel 104 (Figure 3) are introduced into the housing part 5IB below the infra unit 50, which are directed mainly to the above-mentioned supply flow Fc. Infrakäsittely-

The blows F1 n are introduced inside the inner housing parts 54A and 54B surrounding the Jj and are led in the direction of the arrows F1 and F1 to cool the parts heated by the inflatable, and these cooling flows are at least partially directed to the infrared treatment interval and coincide with the sealing and supply flows F1 and Fg. . After the infra-processing interval, the channels 62A and 62B, which communicate with the housings 30 106A and 106B, open in the vicinity of the web W over its entire width. Tubes 56A and 56B emanate from said housings 106A and 106B and merge with the tube 105 shown in Figure 3. The housings of the infra unit 50 and the fluidized bed unit 80 are of unitary construction and there are partitions 63A and 63B between said units, optionally provided with thermal insulation. Although in connection with Fig. 2 the web 35 has been shown to run in a horizontal plane through the infrared processing space and the immediately following fluidized bed processing space 80V, the web may just as well be sloping or vertical as in the embodiment 10 of Fig. 1. The vertical run from the groove G can also be directed from top to bottom.

The infrared radiators 60 are divided into compartments 5 60 ^ ... 60 ^, each of which can be supplied with adjustable electrical power via the electric line 150 (Fig. 3) so that the transverse profile of the heating effect can be controlled by electrical systems known per se. The profile adjustment system also includes transverse humidity profile measuring devices (not shown).

10

Below the infra units 60, there are windows 60A against the processing space, through which the infrared radiation R is applied to the web W penetrating inside it, partially passing through the web W and returning to the web W to act through the reflecting surface 63.

15

Figures 2C and 2D show two alternative constructions of the nozzle 85 of the toy cultivator 80. Figure 2C is a floatsuutln which comprises a housing part 86A, into which the blow air is introduced in the direction of the arrow. Said hot and drying air is distributed to the side channels 87a and 87b on the sides of the nozzle housing 86A 20, to which partial flows are directed from the flow. At the U-side end of the side channels 87a and 87b there are nozzle slots 88A and 88B which blow against each other. jets F ^ a and ralna W along the bearing surface 89A. In the middle of said bearing surface 89 there is a recess S. As described above, a pressurized web stabilizing dry support area K + is formed, from which air is discharged as flows F. and F., on the sides of the nozzle housing 85 so as to generate sufficient turbulence 4a and good heat transfer between the blowing air jets W and ralna.

Fig. 2D shows another alternative foil-type nozzle comprising a nozzle housing 86B with one side channel 87 having a nozzle slot 88 at the W end of the web. Blowing air is introduced into the nozzle housing 86B as a flow F1 which divides into a side channel 87 F ^ along the coanda plane 88C 35 after the nozzle 88, following said surface 88C in sector a and detaching from said bearing surface before the planar bearing surface 89B, in connection with which a vacuum bearing surface is formed and a drying interval K- from which air is discharged.

II

75009 1 in the same direction between the nozzle housings 85. Figure 2 shows how the nozzles shown in Figures 2C and 2D are positioned relative to each other. In the fluidized bed dryer according to the invention, nozzles other than those shown in Figures 2C and / tal 2D can also be used.

5

Figures 4A and 4B show a graphical comparison of the cooling efficiencies (kg / m h) of the prior art dryer shown in Figure A and the dryer shown in Figure 1 according to the invention.

According to Fig. 4A, in a previously known dryer such as Fig. A, which consists of two separate infrared dryers and a reversing cylinder between them, evaporation in the region of the first infra unit rises to n · 40 kg / mh in the interval t ^ -t2, followed by free export, following the first infra unit, the evaporation 2 15 decreases in the interval tas 1 to n * 25 kg / m h. Thereafter, in the region of the reversing cylinder (23A) the evaporation remains low and rises to the level 2 at about 25 kg / mh at time t ^, at which point the free export after the reversing cylinder (23A) begins. The time interval t ^ -tg describes the second infra unit instead of the fluidized bed dryer 26 shown in Fig. A. This is followed by a free export at interval t, -t, by which the evaporation decreases substantially exponentially.

When comparing the evaporation efficiency of the infrared fluid dryer according to the invention shown in Fig. 4B with that shown in Fig. 4A, the following can be stated.

During the time interval tj, the web w passes through the infrared processing interval 50 of the infrared processing unit according to the invention. The length of said infrared processing interval is e.g. about 400 mm. In said interval, the β-cooling power rises from zero to a level of about 40 kg / m 2 h, followed by the treatment interval 80V of the fluidized unit 80 of the dryer according to the invention. From time t1 onwards, the evaporation rises very sharply so that a evaporation peak Hp., 2 1 is formed, the peak of which is at a level of about 180 kg / m 2 h. after the peak of the evaporation peak, the evaporation power decreases to a level of about 70 kg / m h up to time t_, which represents the end point of the handling range J 2 80V. The above evaporation peak Hpl is volatile energy is fed inside the structure of the rack W, which is "discharged" as the evaporating power in the fluidized bed 80V due to the efficient ventilation 7,500 9 1 prevailing therein. In Fig. AB, the width Hp ^ of the evaporation peak is denoted by t ^ t.

The width t of the evaporation peak is generally in the range tg to 0.1 to 0.5 s, preferably tp = 0.15 to 0.3. In Fig. AB t ^ «0.2 s, when the velocity v ^> 10 m / s. The length of the air treatment interval 80V, which represents the above-mentioned time interval tj-t ^, is about 5 m. After said evaporation peak t ^, the evaporation power drops in the time interval t ^ -t ^, which in Fig. 1 represents between the infra-fluid unit AO and the subsequent conventional toy unit 90 web W free export. Thereafter, in the processing interval 90V of the toy unit 90, which corresponds to Fig. AB

the time interval t, -t, -, the wear power rises substantially exponentially from the level of 4 2 2 10 le to about 80 kg / mh, after which it suddenly drops to the level of about 20 kg / mh, where evaporation is in the free space before the multi-cylinder dryer, AB time interval t ^ -tg.

As shown in Fig. 2, the processing interval of the infrared gun 50 and the processing distance 80V of the fluidized bed 80 are in the same plane so that the web W1 has no bends as it passes through the combined infrared fluid dryer AO. Due to the sealing and the convex blows, the web W is initially made to pass stably into and through the infrared processing interval, and the stabilized export of the web W continues in the processing interval 80V of the toy unit 80. Partly because of this, quite high web speeds can be used, which can even considerably exceed a speed of 1000 m / m.

In this way, water is rapidly evaporated from the surface of the coating of the web W, and in the fluid unit 80 immediately following the infra unit 50, the location of the solidification surface of the coating substrate 80 can be advantageously adjusted to a free space after the fluid unit 80, for example. In this way, the occurrence of the mottling phenomenon is presented. The strong evaporation peak H 2 immediately after the coating event also reduces the occurrence of gold roughening.

Figure 3 shows an embodiment of an air system applicable in connection with the method of the invention and the device. The drying air is introduced through the duct 100 to the filter 101 and from there on to the suction duct 102 of the fan 103. The pressure duct 10A of the fan 103 is connected by pipes 52A.53A and 52B.53B to the infrared unit housings 51A.5AA and 51B, 5AB, 35 branching from the nozzles 55A shown in Fig. 2 discharged by escort blows FA and F ^. The air cooling the infra unit 50 is recovered as replacement air for the toy unit 80 and / or 90.

13 75009 1 As shown in Fig. 3, a suction duct 105 starts from the chambers 106A and 106B, through which the combustion air of the burner 116 is led to the fan 107 of the fluidized unit 80. The suction side of said adjuster is indicated by reference numeral 120. The fan 107 of the discharge channel is derived from the gas to the burner 116, 5 which will my8s 113 of the discharge channel of the second fan. Said blower 113 connected lmukanavan 115 is a controller 121. The gas burner 116 of the output side of channel 110 leading to hot and dry air leijuyksikön 80 suutlnlaatlkoihin 82A and 82B. The nozzle boxes 82A and 82B through the duct 111 into the air passage 115 between the channels 110 and 111 is 10 ohltuskanava 112 with a controller 114. The channels 115 and 111 leading to discharge conduit 122 and from there to the exhaust fan 132 of the suction passage 131 with a controller 133. Channel 105 and 112 has a fan 125. The cooling air duct 105 of the infra unit 50 is also led to the intake duct of the combustion air fan 140 of the separate infra unit 90 and to the exhaust duct 130 of the separate fluid unit 90. Otherwise, the air arrangement of the fluid unit 90 is similar to the fluid arrangement 80 described above.

In the embodiment shown in Figs. The heating air of the blowing air of the conventional fluidized bed dryer 90 is, for example, in the order of P ^ 1300 kW.

In the embodiments of the invention, the electrical power of the infra unit 50 is preferably Pg (2 ... 3) x Pj. Considering the total power of the dryers 40 and 90 of the coating station 20, it is in the case shown in Figures 1 and 3 P.. P + P. + P „740 + 300 + 1300 = 2340kW. Preferably, in the invention, the electrical power P of the infra unit 50 is about 25-40% of the total power P., preferably 30-35%. It can be seen from the above that the invention can cope with a relatively small proportion of the more expensive electric power P and the air heating energies Pj and P ^ can preferably be taken from natural gas, if available or the like, from cheaper energy than electrical energy. Thus, thanks to the invention, the advantageous effects of infrared drying can be achieved with a relatively small proportion of electrical power.

7500 9 1 The following are claims which, within the scope of the inventive idea defined by it, the various details of the invention may vary and differ from those set forth above by way of example only.

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Claims (12)

A method for contactless drying of a pepper or cardboard web (W) or another corresponding continuous web (W), wherein the method of drying involves both infrared radiation (R) and drying air streams, by means of which the web (W) which moves through the dryer (40) at the same time, contactless, preferably double-sided, is supported, and in which method the web (W) is moved after said space for infrared drying, almost immediately to a floating drying space (80V), where the web (W) is supported. dried by air sprays characterized in that, in the method, the web (W) is first led to a space for infrared drying, where a relatively short-term drying energy pulse is directed on the web (W), which energy pulse is substantially greater than the average drying effect of the dryer per surface unit. introducing air (F .., F „) into the infrared unit (50), or after heating the Ain uin to the Infrared unit (50) is conducted as replacement air and / or drying air for the float drying unit (80; 90) or the units (80.90) after the infrared unit. 1 Patent Claim 7 50 0 9 2. A method according to claim 1, characterized in that the air currents (F .., F „.) To be introduced into said infrared unit (F) are connected to the path gap (U). The nozzles (55A, 55B) are blown to the space of infrared treatment AD to support the web (W) and cool the devices 1 associated therewith. Method according to Claim 1 or 2, characterized in that the web (W) after the combined infrared and float drying unit (40) is contactlessly dried and supported in a conventional float drying unit (90). Method according to any of claims 1-4, characterized in that the replacement air to be supplied to the float drying unit (80) or units (80.90) is taken in its entirety from the supply (F.) to the infrared (50). The cooling air, which is also used Ain Bin II 7 5009 1 for sealing the length gap (G), the support of the web (W) and the escort in the infrared space starting from its entrance gap (G). 5. A method according to any of claims 1-4, characterized in that the electrical power (P) of the infrared drying directed at the web in the S combined infrared drying unit (40) is about 2 ... 3 times greater than the power (P ^) used for heating the drying air in the float drying unit (80) (P * (2 ... 3) x P.). S * 10 6. A method according to any one of claims 1-5, characterized in that the electrical power (P) which in the process achieves the infrastructure radiation (R) directed at the path (W) is about 25-40%, most preferably about 30-35%, of the total drying effect (P) directed in the dryer to the web (W). 15 Process according to claim 1, characterized in that gas is used in the process for heating the drying air in the float drying unit (80) or units (80,90). Drying device intended to carry out the method according to any of claims 1-7, which device comprises an infrared drying unit (50) and a floating drying unit (80) or floating drying units (80.90), which infrared drying unit (50) comprises a series (60). 60) infrared devices (60) and an infrared space provided therewith, through which the web (W) to be dried can be guided, and which float-drying unit (80) or units (80,90) comprises a cover portion ( 81), below which a nozzle seals or valves (82A.82B) are provided, in connection with which there are nozzle parts (85A, 85B) through which the drying and supporting air jets (F3; F3a * F3b) direct the web (W). to be dried, the infrared drying unit (50) and the swivel drying unit (80) being integrated with each other in constructional and functional terms and the infrastructure unit (50) being immediately in front of the float drying unit (80) in the running direction (W (W) s if it is to be dried, characterized in that the infrared drying unit (10) has air and nozzle devices (52A, 53A, 55A, 52B, 53B, 55B), through which air streams can be directed into the treatment space and / or in connection with the parts of the infrastructure being heated, which