METHOD AND A SYSTEM FOR A YANKEE CYLINDER IN A TISSUE MACHINE

Abstract

The invention relates to a method and system for improving the application of a coating on a Yankee cylinder (CR) in tissue paper machines. The invention implements a moisture-controlled environment (12) in an area of the exposed Yankee cylinder between the take-off position (TO) and ahead of the transfer position (TP) of the web, i.e. before and/or after the application of a coating with Performance Enhancing Material (PEM), wherein the cooling effect on the Yankee surface is increased by increased evaporation rate of water in the coating or water additionally applied onto the coating.

Claims

1-33. (canceled)

34. A method of controlling the application of a coating containing a water solution of a Performance Enhancing Material (PEM) on a surface of a Yankee cylinder ahead of the Transfer Position (TP) of a tissue web onto the Yankee cylinder comprising: taking off the dried and creped tissue web (W) from the Yankee cylinder (CR) in a take-off position (TO); establishing at least one moisture-controlled environment in the area between the take-off position (TO) and the Transfer Position (TP) of the tissue web onto the Yankee cylinder, said moisture-controlled environment establishing a humidity that is at least 20 percentage units lower than the humidity established in this environment without having any moisture-controlled environment; and cooling the surface of the Yankee cylinder in the moisture-controlled environment by increasing evaporation rate of water in or applied onto the Performance enhancing material.

35. The method according to claim 34, wherein a first coolant is added into the moisture-controlled environment and said first coolant preferably is air.

36. The method according to claim 35, wherein the first coolant is distributed continuously over the entire width of the Yankee cylinder.

37. The method according to claim 36, wherein the coolant is distributed over the entire width (W.sub.W) of the Yankee cylinder using a slot (S) or multiple nozzles (12n) arranged over the entire width of the Yankee cylinder.

38. The method according to claim 37, wherein each slot gap (S) or nozzle (12n) is adjustable.

39. The method according to claim 34, wherein the moisture-controlled environment is shielded on at least 3 sides of the moisture-controlled environment and said moisture-controlled environment open towards the exposed outer cylindrical surface of the Yankee cylinder (CR).

40. The method according to claim 34, wherein a second coolant used is a liquid coolant applied onto the outer cylindrical surface of the Yankee cylinder, which liquid coolant is evaporated in said moisture-controlled environment after being applied onto the outer cylindrical surface of the Yankee cylinder ahead of the moisture-controlled environment.

41. The method according to claim 38, wherein at least two different coolants are used in the moisture-controlled environment in at least two different zones of the moisture-controlled environment.

42. The method according to claim 34, wherein the temperature on the surface of the Yankee cylinder is measured after the moisture-controlled environment and the coolant supply is controlled in order to reach a target temperature.

43. The method according to claim 42, wherein the temperature in the moisture-controlled environment is lowered at least 20° C. compared to not using a moisture-controlled environment, and preferably establishing a temperature of the moisture-controlled environment within the range 20-80° C.

44. A system of controlling the application of a coating containing a Performance Enhancing Material (PEM) on a surface of a Yankee cylinder ahead of the transfer position (TP) of a tissue web onto the Yankee cylinder comprising: a doctor blade (10) taking off the dried and creped web (W) from the Yankee cylinder (CR) in a take-off position (TO): an application position (TP) of the Performance Enhancing Material (PEM) onto the Yankee cylinder arranged after the take-off position; and at least one moisture-controlled environment arranged in the area between the take-off position (TO) and the transfer position (TP) of the tissue web onto the Yankee cylinder by supplying low moisture air from a low moisture air source to the moisture-controlled environment, wherein: said moisture-controlled environment establishes a humidity that is at least 20 percentage units lower than the humidity established in this environment without having any moisture-controlled environment; and the surface of the layer of Performance Enhancing Material (PEM) applied onto the Yankee cylinder is cooled in the moisture-controlled environment by increasing evaporation rate of water in or applied onto the Performance enhancing material.

45. The system according to claim 44, wherein the low moisture air source (Air.sub.1, Air.sub.2) is air taken from the machine hall of the Yankee cylinder or air taken externally from the machine hall of the Yankee cylinder.

46. The system according to claim 44, wherein the coolant (Cool.sub.1, Cool.sub.2, Air.sub.1, Air.sub.2) is continuously distributed over the entire width (W.sub.W) of the Yankee cylinder (CR) by a distribution boom (12/20), using multiple nozzles (12n) or a continuous slot (S) arranged over the entire width of the Yankee cylinder on said distribution boom (12).

47. The system according to claim 46, wherein each nozzle (12n) or slot gap is adjustable by a control system (CPU, V.sub.1, 12.sub.c) in order to reach a target temperature.

48. The system according to claim 44, wherein the moisture-controlled environment is shielded from the application position (TP) of the Performance Enhancing Material (PEM) onto the Yankee cylinder using at least one shield wall (13a/13b) located with one end of the shield wall (13a/13b) close to surface of Yankee cylinder, at a short distance (d), and the other end of the shield wall at a remote distance (d) exceeding 5 centimeters from the creping roll.

49. The system according to claim 48, wherein the moisture-controlled environment is shielded on at least 3 sides of the moisture-controlled environment by shield walls (13a/13b) and said moisture-controlled environment open towards the exposed outer cylindrical surface of the Yankee cylinder (CR).

50. The system according to claim 44, wherein a second coolant source (Cool.sub.1, Cool.sub.2) is a liquid coolant that is applied on the surface of the Yankee cylinder before the application position (TP) of the Performance Enhancing Material (PEM) onto the Yankee cylinder said liquid coolant increasing the volume of evaporable liquid in the residual layer of Performance Enhancing Material (PEM) left on the Yankee after the doctor blade (10) or second coolant source (Cool.sub.1, Cool.sub.2) is a liquid coolant that is applied on the surface of the Yankee cylinder after the application position (TP) of the Performance Enhancing Material (PEM) onto the Yankee cylinder, said liquid coolant increasing the volume of evaporable liquid in the Performance Enhancing Material (PEM) applied.

51. The system according to claim 44, wherein at least two different coolant sources (Air.sub.1, Air.sub.2, Cool.sub.1, Cool.sub.2) are used in at least two different zones (I, III, IV) of the moisture-controlled environment.

52. The system according to claim 44, wherein a temperature sensor (16b) is arranged after the moisture-controlled environment and before the application position of the Performance Enhancing Material (PEM), measuring the temperature on the surface of the Yankee cylinder having passed the moisture-controlled environment or a temperature sensor (16b) is arranged after the moisture-controlled environment and after the application position of the Performance Enhancing Material (PEM), measuring the temperature on the PEM coating applied on the surface of the Yankee cylinder having passed the moisture-controlled environment.

Description

LIST OF DRAWINGS

[0076] FIG. 1; shows a schematic side view of a first embodiment of the invention where a tissue web is fed to a Yankee cylinder in a transfer position and removed from the Yankee cylinder in a take-off position with cooling of the PEM coating after application of the coating.

[0077] FIG. 2; shows a spray boom for PEM and associated PEM supply system.

[0078] FIG. 3a; shows a first embodiment of a distribution boom used in the invention, feeding low moisture air, or additional cooling liquid, onto the outer surface of the Yankee cylinder.

[0079] FIG. 3b; shows a second embodiment of a distribution boom used in the invention, feeding low moisture air, or additional cooling liquid, onto the outer surface of the Yankee cylinder.

[0080] FIG. 3c; shows a cross section of the distribution boom used in the second embodiment as seen in the view a-a in FIG. 3b.

[0081] FIG. 4; shows schematically the temperature profile on the tissue web from the transfer position and 5 meters after the transfer position.

[0082] FIG. 5; shows a schematic side view of a second embodiment of the invention in the same side view as in FIG. 1 with cooling of the PEM coating after application of the coating;

[0083] FIG. 6; shows a schematic side view of a third embodiment of the invention in the same side view as in FIG. 1 with cooling of the PEM coating after application of the coating.

[0084] FIG. 7; shows a schematic side view of a fourth embodiment of the invention in the same side view as in FIG. 1 but with cooling liquid applied onto the Yankee cylinder and subsequent increase evaporation rate in a low moisture zone before application of the PEM coating.

[0085] FIG. 8; shows a schematic side view of a fifth embodiment of the invention in the same side view as in FIG. 7 with a shielded low moisture zone before application of the PEM coating;

[0086] FIG. 9; shows a schematic side view of a sixth embodiment of the invention in the same side view as in FIG. 7 with multiple shielded zones before application of the PEM coating;

[0087] FIG. 10; shows a schematic side view of a seventh embodiment of the invention in the same side view with a shielded zone with application of cooling liquid on the Yankee cylinder before application of the PEM coating as well as a shielded low moisture zone whit increased evaporation effect after the application of the PEM coating.

DETAILED DESCRIPTION OF THE INVENTION

[0088] Before describing the invention, reference is made to FIG. 4 in which the typical tissue web temperature profile is shown. Conventionally the temperature of the tissue web transferred to the Yankee cylinder is about 40° C. and with a moisture content of about +40%. As seen here, the temperature of the web increases rapidly from the transfer position from about 40° C. to about 98-99° C., within 1 meter from the transfer position, wherein the bulk part of moisture is evaporated. As long as there is water enough to evaporate, the temperature will be kept roughly constant, as the evaporation per se chills of the web, preventing further heating of the web from the hot Yankee cylinder. The insight in this well-known temperature profiling indicates that the layer on the hot Yankee, in this case the paper web, may be kept below 100° C. as long as there is enough water in the layer being subject to evaporation.

[0089] After about 1.5 meters from the transfer position, the paper web is heated further as most moisture is gone, and thus evaporation of water could not reduce temperature increase of the web. After about a further 0.3-0.5 meters a second constant temperature zone is established, but after some 2.7-2.8 meters from the transfer position, the temperature of the web is increasing again and reaches a final temperature close to the temperature of the Yankee cylinder surface, i.e. about 140° C., and a final moisture content of less than 5%.

[0090] In this example, the Yankee cylinder is obtaining a dry tissue web within about an angle of wrap α corresponding to a about 4.5 meter of the circumferential length of the Yankee cylinder. The actual circumferential length that the web needs to be applied on the Yankee cylinder naturally depends upon the speed of the web, i.e. production capacity. With a typical speed of about 1500 m/minute the angle of wrap should increase proportional to speed increase, using same conditions in the tissue machine, and in such set-up the wrap angle should increase about ⅓ if web speed is increased from 1500 to 2000 m/minute. However, such reconfiguration of the tissue machine is costly due to major rebuild requirements for rolls, and therefore are instead drying conditions altered, for example by increasing temperature of the Yankee cylinder and/or in the hood.

[0091] In FIG. 1 a first embodiment of the invention is shown. The invention is related to the Yankee cylinder CR and using this Yankee cylinder to obtain a creped web product. As indicated in positions C1, C2 and C3 the web may be conveyed to the Yankee cylinder CR as a plain web W as shown schematically in C1. The web W is transferred to the surface of the Yankee cylinder CR by a transfer roll 1 in a nip in a transfer position TP.

[0092] If this transfer is done during a relative speed difference, i.e. a lower speed of the Yankee cylinder, a first order of crepe effect could be obtained in the web W as schematically shown in C2. However, a first crepe effect may also be obtained in preceding transfer nips ahead of the transfer to the Yankee cylinder.

[0093] The web runs over the surface of the Yankee cylinder CR at an angle of wrap α that may be in any order of 100-270°, and as shown in this figure in an order of wrap at about 190-200°. The web is conventionally dried as the Yankee cylinder CR is heated internally by pressurized hot steam. At the end of the angle of wrap, the finally dried web is taken off in a take-off position TO by a doctor blade 10. This doctor blade may induce yet an additional creping effect, increasing the crepe as schematically shown in C3. As indicated in FIG. 1 a hood H may also be provided that further heats the web with hot air.

[0094] After the doctor blade 10, as seen in the rotational direction R of the Yankee cylinder, an additional cleaning device 11 may be arranged, which cleaning device release any residual fibers from the Yankee cylinder. The cleaning device may be an additional doctor blade, or any brush like cleaning device.

[0095] After the cleaning device a PEM supply boom 14 is arranged. The PEM mixture is thus applied on the Yankee cylinder, allowing the coating to spread out evenly on the Yankee cylinder. Typically, the PEM mixture is cooled and as it contains a lot of water the coating mixture will maintain a temperature less than 100° C. as long as water may evaporate.

[0096] Now, according to the invention a low moisture air boom 12a is arranged after the PEM supply boom 14, as seen in the rotational direction R of the Yankee cylinder. This low moisture air boom 12a is connected to a low moisture air source Air.sub.1, and with a control valve V.sub.1 arranged in the supply pipe connected to the low moisture air boom 12a. The flow of low moisture air is preferably passing through a conditioner 17 where the coolant is chilled and dried. This creates a moisture-controlled environment cooling the exposed PEM coating by increased evaporation rate of the water content of the PEM coating.

[0097] A shield wall 13a is preferably arranged ahead of the moisture-controlled environment, with the end part located at a short distance d between the Yankee cylinder CR surface and the end part of the shield wall. The purpose of using a shield wall is to reduce any impact between the application of the PEM coating and any turbulence or air flow in the moisture-controlled environment. Said distance d may be set to any suitable range between 0.1 to 4 millimeters.

[0098] The expression moisture-controlled environment is hereinafter used to define a zone where the moisture level close to the web may be lowered considerably in comparison to the moisture level that is established by a not using a moisture-controlled environment. The temperature in the moisture-controlled environment may preferably be lowered from about 80-130° C. down to at least 40° C., or in the range 20-60° C., and hence a minimum reduction of the temperature of at least 20° C.

[0099] A temperature sensor 16a may be arranged after the cooling boom 12a. This temperature sensor may preferably be connected to a control unit CPU that may control the supply of the low moisture air by regulating the control valve V.sub.1.

[0100] Finally, after the application of the PEM coating a thickness sensor 15 may also be arranged, that may detect the thickness of the coating applied. This thickness sensor 15 may preferably be connected to the control unit CPU that may control the supply of the PEM coating by regulating the control valve V.sub.2.

[0101] In FIG. 2, an embodiment of the PEM supply boom 14 is shown, extending over the entire width W.sub.W of the web. This PEM supply boom may have a multitude of individual PEM supply nozzles 14n, each with an individual control valve 14c connected to a control unit CPU. The supply nozzles are preferably fan jet nozzles, with fan jets extending with the width of the fan jet across the width of the web. Each fan jet ends when next neighboring fan jet nozzle takes over, thus covering the entire width of the web. The PEM source may be water, the main component in volume, with additives mixed into it, only PVOH (polyvinyl alcohol) shown as an example of the additives added. The high molecular weight polymer added needs a long residence time in the water mixture in order to untangle the long polymeric chains, and the resulting mixture may be feed to a buffer storage as shown in the figure where the residence time may be between 30-240 minutes. Thereafter the PEM mixture is pumped to the PEM supply boom 14 with a pressurizing pump P.sub.1. The PEM mixture may also have a return pipe connected to the buffer storage, allowing a developed flow along the entire length of the PEM supply boom which prevents solids in the solution from settling.

[0102] In FIG. 3a an embodiment of the distribution boom 12/20 is shown, extending over the entire width W.sub.W of the web. The same kind of distribution boom may be used both for distributing low moisture air as well as cooling liquid. What is later on described for the low moisture air boom 12 applies as well for a cooling liquid boom 20.

[0103] The low moisture air boom 12 is similar in all examples with references 12a, 12b, both of them arranged after the PEM spray boom 14, or 12c, 12d and 12e, all of these arranged ahead of the PEM spray boom 14.

[0104] This low moisture air boom 12 may have a multitude of individual low moisture air supply nozzles 12n, each with an individual control valve 12c connected to a control unit. The supply nozzles 12n are preferably fan jet nozzles, with fan jets extending with the width of the fan jet across the width of the web. The fan jet ends when next neighboring fan jet take over, thus covering the entire width of the web.

[0105] The low moisture air source Air.sub.1 may be ambient air.

[0106] In the case where ambient air is used as low moisture air source, the velocity of the cooling air is regulated by pressure in the supply boom. Test with air as coolant have shown that the required pressure in the supply boom should be in the range of 2 kPa only, and the required air volume in the range of 175 m.sup.3/min for a 200 inch (in web width) tissue machine

[0107] The low moisture air is pumped with a pressurizing pump P.sub.2 to the low moisture air boom 12 at increased pressure. As shown here, a part of the low moisture air supplied to the low moisture air boom 12 may be exhausted through a pipe Ex in the other end, for example if ambient air is used, but this exhaust pipe may be closed if more expensive coolant is used.

[0108] In FIG. 3b an alternative embodiment of the low moisture air boom 12 is shown which extends over the entire width W.sub.W of the web. This low moisture air boom may have a single continuous slot S (as shown in FIG. 3c). The supply slot S is shown in FIG. 3c as seen through the cross-section view a-a in FIG. 3b. The slot width, and thus the low moisture air supply rate, may be controlled by a control unit CPU by a servo unit 12s that rotates one of the inner or outer coaxial pipe members 12i or 12o in relation to each other. In tests performed with air as coolant, a slot width of about 10 mm was used and the entire cooling boom could be adjusted changing the direction of the slot. The slot establishes a continuous flat flow of low moisture air over the entire width W.sub.W of the web. In this embodiment an exhaust pipe is not used.

[0109] In FIG. 5, a second embodiment of the invention is shown. In relation to the first embodiment shown in FIG. 1 the moisture-controlled environment is shielded on at least 3 sides of the moisture-controlled environment and said moisture-controlled environment opens towards the exposed outer cylindrical surface of the Yankee cylinder CR. This will assure that the low moisture air supplied into the moisture-controlled environment will flow towards the surface of the Yankee cylinder, and that the flow of low moisture air supply will not disturb the preceding application of a PEM layer.

[0110] In FIG. 6, a third embodiment of the invention is shown. In relation to the first embodiment shown in FIG. 1 this embodiment is arranged with two low moisture air booms 12a and 12b respectively that are connected to two independent low moisture air sources. One of the low moisture air sources may be ambient air and the other cooled air from the tissue machine hall. The valves in the supply pipes may be controlled in the same manner as in the first embodiment.

[0111] In FIG. 7, a fourth embodiment of the invention is shown. In contrast to embodiments shown in FIGS. 1, 5 and 6 this embodiment includes usage of an additional cooling boom 20a that applies a liquid coolant on the surface of the Yankee, said applied liquid thereafter evaporated in the subsequent moisture-controlled environment established by a low moisture air boom 12c arranged after the cleaning device 11 and the cooling boom 20a, as seen in the rotational direction R of the Yankee cylinder. This low moisture air boom 12c is connected to a low moisture air source Air.sub.1, and with a control valve V.sub.3 arranged in the supply pipe connected to the low moisture air boom 12c. This creates a moisture-controlled environment cooling the exposed surface of the Yankee cylinder having the liquid coolant layer. This provides for an evaporative cooling of any residual PEM coating that is left on the Yankee cylinder after the doctor blade. The residual PEM coating may then be cooled by evaporation of the applied liquid layer before application of new fresh PEM coating. A shield wall 13b is preferably arranged after the moisture-controlled environment, and a temperature sensor 16b may be arranged on the shield wall 13b. This temperature sensor may preferably be connected to a control unit CPU.sub.1 that may control the supply of the low moisture air by regulating the control valve V.sub.3 and control the supply of liquid coolant by regulating the control valve V.sub.4.

[0112] After the moisture-controlled environment, a PEM supply boom 14 is arranged. The fresh PEM is thus applied on a cooler surface of the Yankee cylinder, and the residual PEM layer is prevented from turning glassy due to the evaporation of the liquid layer applied on top of the residual PEM layer.

[0113] Finally, after the application of the PEM coating a thickness sensor 15 may be arranged, that may detect the thickness of the coating applied. This thickness sensor 15 may preferably be connected to a control unit CPU.sub.2 that may control the supply of the PEM coating by regulating the control valve V.sub.2. In practice a common control unit may be used that control both thickness and temperature.

[0114] In FIG. 8 is shown a fifth embodiment of the invention. In relation to the embodiment shown in FIG. 7 the moisture-controlled environment is shielded on at least 3 sides of the moisture-controlled environment and said moisture-controlled environment opens towards the exposed outer cylindrical surface of the Yankee cylinder CR. This will ensure that the low moisture air supplied into the moisture-controlled environment will flow towards the surface of the Yankee cylinder, and that the flow of coolant supply will not disturb the following application of a PEM layer.

[0115] In FIG. 9, a sixth embodiment of the invention is shown. In relation to the embodiment shown in FIG. 7, the moisture-controlled environment is divided into 4 individually shielded zones I-IV.

[0116] In the first zone I a first cooling boom 20a may be located, preferably distributing a cooling liquid in mist form with a temperature of the cooling liquid close to the evaporation temperature.

[0117] In the second zone II an evacuation pipe 12x may be connected to low pressure, especially if the cooling liquid supplied in the preceding zone is liquid. The evacuation will lower the pressure and assist in evaporation and evacuation of evaporated residual cooling liquid.

[0118] In the third zone III a second cooling boom 20b may be located, preferably distributing a cooling liquid.

[0119] Finally, in the fourth zone IV a third low moisture air boom 12c may be located, preferably distributing a low moisture air.

[0120] This sequential cooling in successive zones may be implemented if the cooling effect is to be optimized, wherein each individual cooling zone in the moisture-controlled environment may be individually regulated for highest possible cooling effect. Each successive cooling zone is shielded on at least 3 sides of each zone of the moisture-controlled environment and said moisture-controlled environment open towards the exposed outer cylindrical surface of the Yankee cylinder CR. This will ensure that the low moisture air supplied into the moisture-controlled environment as well as cooling liquid will flow towards the surface of the Yankee cylinder, and that the flow of low moisture air as well as coolant supply will not disturb each other as well as the following application of a PEM layer. Each zone may also be closed by walls (not shown) in their gable ends (the outer ends at the ends of the web width), possibly with evacuation ducts for coolant excess or evaporated moisture in said gable ends.

[0121] Finally, in FIG. 10, a seventh embodiment of the invention is shown. In this embedment is a first shielded cooling zone with application of liquid, preferably water, to be evaporated arranged before the PEM spray boom 14, and one shielded moisture-controlled environment arranged after the PEM spray boom 14. Each respective zone is controlled as shown in preceding embodiments, using temperature sensors 16a, 16b after each zone and a final PEM thickness measurement 15.

[0122] The embodiments shown implement at least one moisture-controlled environment immediately after the PEM spray boom or a moisture-controlled environment immediately ahead of the PEM spray boom. Both moisture-controlled environment zones reduce heating of the PEM coating and the PEM coating will have a lower temperature when reaching the transfer point where the tissue web is applied onto the PEM coated surface of the Yankee cylinder. This will reduce viscosity of the PEM coating and reduce PEM coating from diffusing into the tissue web.

[0123] The best effect is obtained from cooling the surface of the PEM coating after the PEM spray boom and using air as the coolant. The water content in the PEM coating when reaching the transfer position should be as low as possible, as high water content in the PEM coating in transfer position may reduce wet tack and web/sheet transfer to the Yankee cylinder will be poor and uneven. This will cause uneven crepe structure and wavy diameter in the final pick up roll.

[0124] However, liquid may be used as coolant especially in the cooling zones preceding the PEM spray boom. As the PEM mixture per se contains typically +90% water, no negative impact will occur if water residues are left on the Yankee cylinder surface when applying the PEM coating. On the contrary, if the water content is increased somewhat the maximum coating temperature of 100° C. will be maintained longer as long as there is water in the PEM coating to be evaporated.

[0125] Small amounts of water added after applying the PEM coating, for example as a mist, is acceptable if these amounts have time to evaporate before the transfer position.

[0126] The basic feature of the invention is the application of a moisture-controlled environment with lower moisture level than normal. This improves evaporation rate in the PEM coating. This could be made as one or more individual zones all having a moisture-controlled environment.

[0127] The moisture-controlled environment may be established in the simplest embodiment by blowing air from the machine hall into the area beneath the Yankee, said air having a much lower temperature than the temperature without supplying this replacement air.

[0128] The replacement air may alternatively be recirculation of the air in this environment through a dehumidifier that condenses most of the humidity before reintroduction. It may also be replacement air that is additionally cooled by coolers before being supplied.

[0129] However, less relative humidity is essential. The replacement air may also be heated such that the moisture level drops at least 20%, but colder air is preferred.

[0130] When the relative humidity in the moisture-controlled environment has been lowered may an increase in the evaporation effect be obtained by adding water to the PEM coating, which may guarantee that the temperature of the PEM coating stays below 100° C. As long as there is water in the PEM coating the temperature will stay below 100° C. as this is the evaporation temperature of water.

DRAWINGS CATALOGUE

[0131] 1 Transfer Roll [0132] 10. Doctor Blade [0133] 11. Cleaning Device [0134] 12 Cooling boom [0135] 12n cooling boom nozzle [0136] 12c cooling nozzle valve [0137] 12o Outer tube in boom [0138] 12i Inner tube in boom [0139] 12a First air cooling boom after PEM application [0140] 12b second air cooling boom after PEM application [0141] 12c First cooling boom ahead of PEM application [0142] 12d Second cooling boom ahead of PEM application [0143] 12e Third cooling boom ahead of PEM application [0144] 12x Evacuation pipe [0145] 13a Shield wall PEM cooling/13b Shield wall precooling [0146] 14 PEM spray boom [0147] 14n PEM nozzles [0148] 14c PEM nozzle valve [0149] 15 Thickness sensor [0150] 16 Temperature sensor [0151] 17 Conditioner [0152] CR Creping roll [0153] W Tissue web [0154] W.sub.w Tissue web width [0155] α The web angle wrap [0156] TP Transfer Position [0157] TO Take-off Position [0158] R Direction of rotation [0159] S Slot [0160] V.sub.1 Control valve after PEM application [0161] V.sub.2 Control valve after PEM application [0162] V.sub.3 Control valve ahead of PEM application [0163] V.sub.4 Control valve ahead of PEM application [0164] Air.sub.1 Second air source [0165] Air.sub.2 Second air source [0166] Cool.sub.1 First Cooling media [0167] Cool.sub.2 Second Cooling media [0168] CPU1/CPU2 Control Units cool/PEM