EP0618328B1 - Dampfsprührohr und Verfahren zum Einstellen von Glanz und/oder Glätte einer Materialbahn - Google Patents

Dampfsprührohr und Verfahren zum Einstellen von Glanz und/oder Glätte einer Materialbahn Download PDF

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Publication number
EP0618328B1
EP0618328B1 EP94103979A EP94103979A EP0618328B1 EP 0618328 B1 EP0618328 B1 EP 0618328B1 EP 94103979 A EP94103979 A EP 94103979A EP 94103979 A EP94103979 A EP 94103979A EP 0618328 B1 EP0618328 B1 EP 0618328B1
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EP
European Patent Office
Prior art keywords
steam
spray pipe
steam spray
pipe according
nozzles
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP94103979A
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German (de)
English (en)
French (fr)
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EP0618328A1 (de
Inventor
Stefan H. Winheim
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VIB Apparatebau GmbH
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VIB Apparatebau GmbH
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Priority claimed from DE19934309076 external-priority patent/DE4309076C2/de
Application filed by VIB Apparatebau GmbH filed Critical VIB Apparatebau GmbH
Publication of EP0618328A1 publication Critical patent/EP0618328A1/de
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    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
    • D21G1/00—Calenders; Smoothing apparatus
    • D21G1/0073—Accessories for calenders
    • D21G1/0093—Web conditioning devices
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F7/00—Other details of machines for making continuous webs of paper
    • D21F7/008—Steam showers

Definitions

  • the invention relates to a steam spray pipe with a supply line for steam, a nozzle arrangement and a valve which is arranged between the supply line and nozzle arrangement, and a method for adjusting the gloss and / or smoothness of a material web guided through a nip arrangement with the aid of such steam spray pipes, in which a The actual value of gloss and / or smoothness of the material web in the running direction behind the nip arrangement is recorded and compared with a target value and the amount of steam emitted by the steam spray pipes is changed zone by zone depending on the difference between the target and actual values.
  • a steam spray pipe and a method for controlling the amount of steam emitted by the steam spray pipe are known.
  • the steam spray tube is arranged below a material web that runs through a calender, in which at least one roller has a highly polished surface.
  • the steam spray tube emits steam through its nozzle arrangement, which condenses in the air and spreads out in the form of a mist of the passing paper web.
  • the resultant increase in moisture in the paper web means that the paper web can be smoothed better in the subsequent nip and / or has a higher gloss.
  • the gloss and / or smoothness of the paper web are measured at the end of the calender, the measured values being fed back to a control device which controls the valves of the steam spray pipe accordingly.
  • the valves are designed as digital valves, so that only a limited resolution of the amount of steam emitted is possible. In order to improve the resolution, the pressure on all steam pipes is readjusted using pre-defined mathematical methods.
  • the invention is therefore based on the object of ensuring adequate moistening even at higher web speeds.
  • a substantially rectilinear acceleration channel is arranged behind the valve in the flow direction of the steam, from which a nozzle channel branches off to the nozzle arrangement at a predetermined distance before the end of the acceleration channel.
  • the length of the acceleration channel up to the branch only has to be so great that the water droplets are accelerated to a speed at this length which is so great that they cannot follow the change of direction of the steam properly due to their inertia. So you can realize much higher steam speeds with such a steam spray tube, so that the emerging from the nozzle assembly Steam also reaches the material web at a higher pressure or at a higher speed. The speed is so high that the steam or the mist formed by it manages to tear open the air layer adhering to the material web and to penetrate as far as the material web. There, the material web is provided with the necessary amount of moisture so that it obtains the desired smoothness or the desired gloss in the subsequent nip.
  • the acceleration duct is preferably arranged in a duct housing which is located entirely in the interior of the feed line.
  • the duct housing of the acceleration duct is therefore always kept at a temperature which corresponds to the temperature of the steam supplied. Water droplets that are introduced into the acceleration channel and remain there due to the lack of evasion can then evaporate again and are thus disposed of without any problems.
  • the end of the acceleration channel is preferably closed off by a baffle plate which has an opening in the region of its lowest point when viewed in the direction of gravity.
  • the water droplets accelerated in the acceleration channel by the steam flow bounce on the baffle plate, since they cannot follow the change of direction when branching off into the nozzle channel, and then flow downwards, where they can flow off through the opening.
  • the acceleration channel is connected to a disposal channel via the opening.
  • the various water droplets no longer get into the supply line, but are discharged or "disposed of” so that they no longer interfere.
  • the opening is preferably designed as a throttle. This ensures that the vapor pressure in the acceleration channel can be significantly higher than in the disposal channel. This ensures that the steam entering the acceleration channel actually exits through the nozzle arrangement and not through the opening. This gives good efficiency.
  • the size of the opening can be chosen so that it is mainly blocked by draining water.
  • the valve is advantageously arranged with its valve seat and closure piece inside the feed line and with its drive part outside the feed line.
  • the valve seat and plug are parts of the valve that are exposed to the steam and on which the steam can condense. If these two parts are arranged in the interior of the feed line, they are already preheated by the steam flowing in the feed line, so that there is no condensation of the steam on these parts.
  • the drive of the valve is arranged outside the feed line. It can therefore be kept cool or colder, which can be of crucial importance for the functionality and service life of the drive.
  • the drive part is preferably thermally decoupled from the supply line, at least with its housing.
  • a heat transfer from the supply line to the drive part does not take place or only to a very limited extent, so that excessive heating of the drive part on the one hand and heat dissipation and thus energy loss on the other hand cannot occur.
  • the valve is preferably designed as a pneumatically controllable analog and in particular linear valve. This allows a very sensitive Reach valve setting. You do not have to rely on a gradation, as occurs with a digigal valve.
  • the design as a linear valve facilitates control.
  • a linear valve has a linear relationship between the amount of vapor passed and the control signal, for example the pneumatic pressure, in otherwise unchanged ambient conditions.
  • An increase in the control signal by 10% also causes an increase in the amount of vapor allowed through by 10%. This can be achieved, for example, by structural measures in which the valve seat and the closure piece are matched to one another accordingly.
  • the nozzle arrangement is preferably directed downward in the direction of gravity. Such an alignment has so far had the disadvantage that water droplets that have been carried in the steam and have not been immediately carried away by the nozzles have accumulated in the area of the nozzle arrangement and sooner or later have necessarily flowed into the nozzles, where they pass through the nozzle escaping steam were ultimately carried away. Since a practically water-free steam now arrives at the nozzle arrangement with the steam spray tube, the nozzle arrangement can also be operated "overhead" and, if this should be necessary or desired, apply steam to the upper side of the material web.
  • the nozzle arrangement is arranged opposite a nozzle arrangement of a second steam spray tube, the direction of the steam emerging from one nozzle arrangement being essentially opposite to that of the steam emerging from the other nozzle arrangement.
  • both sides of the material web can now be applied simultaneously. Both sides of the web can independently of each other with the desired moisture. In particular, they can also be subjected to the same amount of moisture so that treatment of both sides of the material web can be carried out in the nip.
  • the steam spray tube is arranged in front of the first nip of a nip arrangement with a plurality of nips, in particular a supercalender. Most of the surface processing takes place in the first or the first nips of such a nip arrangement. If the material web side or even the material web sides are already exposed to moisture here, the gloss or smoothness result can be improved considerably.
  • the nozzle arrangement has a steam chamber into which the nozzle channel opens on one side and which is provided with nozzles.
  • a steam chamber enables the steam to spread evenly before it exits through the nozzles.
  • the pressure in the entire steam chamber is essentially the same, so that the nozzles, even if they are spatially distributed, are all acted upon uniformly.
  • the steam emerging from the nozzle channel changes its direction of movement in the steam chamber at least once.
  • This provides another way of separating water droplets from the steam.
  • the water droplets cannot take part in the change of direction, especially in the case of steam flowing at high speed, and are therefore discharged from the steam flow flowing to the nozzles. As a rule, they then get to some wall of the steam chamber.
  • a baffle plate is arranged in the steam chamber in the extension of the nozzle channel.
  • the steam flows around the baffle plate.
  • the normal of the baffle plate is preferably inclined with respect to the axis of the nozzle channel.
  • the steam flows out of the nozzle channel, it reaches an inclined plane and can thus be directed towards a steam chamber wall.
  • water drops that form against expectations can run off the baffle plate and be directed into an area outside the nozzles then located below, where they can be removed without disturbing.
  • the baffle plate is connected to the surroundings of the mouth of the nozzle channel via side walls, the side walls opening in the direction of a steam chamber wall. With this, the steam emerging from the nozzle channel is directed even more strongly onto the corresponding steam chamber wall. The steam has a long way to go to an area of the steam chamber where it can relax further. This also helps to avoid droplet formation.
  • the nozzle channel can open-center into the steam chamber, and the nozzles are arranged outside the projection of the mouth of the nozzle channel onto the outer wall of the steam chamber.
  • the steam flowing through the nozzle channel thus accelerates the water droplets that may still be present in the direction of a steam chamber wall, where they are deposited can.
  • the water droplets cannot exit directly through the nozzles.
  • the steam chamber has an essentially circular cross section and the nozzle channel opens into it essentially tangentially.
  • the steam is therefore first routed along the wall of the steam chamber before it can exit the nozzles. This results in a swirl of steam, in which water droplets which may still be present in the steam can be deposited on the wall of the nozzle chamber.
  • the steam chamber is advantageously arranged in a heated housing. Even if droplets are deposited on the wall of the steam chamber, they are evaporated again very quickly, so that no disturbing water or liquid accumulations occur.
  • this embodiment also has the advantage that starting such a steam pipe is made easier. If steam is let into a cold steam pipe, the steam will initially condense on the walls and form water droplets there, which can later escape through the nozzles together with the steam.
  • the steam chamber is arranged in an already heated housing, it has the necessary temperature to prevent the steam from condensing. Even after a standstill, the steam pipe can be put back into operation almost immediately. Because the housing of the steam chamber is heated, the temperature in the steam chamber also rises above the evaporation temperature of the water, so that water droplets possibly entering the steam chamber evaporate anyway.
  • the housing is preferably at least partially formed by a part of the boundary wall of the feed line, which is directed towards the interior of the feed line is formed.
  • the steam chamber is therefore surrounded by the feed line on at least part of its outer circumference and is accordingly heated by the steam flowing in the feed line. This results in a very good and precise coordination of the temperature of the incoming steam with the temperature of the steam chamber, so that condensation of the water cannot occur due to sudden changes in temperature.
  • the nozzles are arranged in a diffuser plate which closes off the steam chamber from the outside.
  • a diffuser plate can be easily manufactured with the necessary accuracy.
  • the design has the advantage of being easy to manufacture.
  • the diffuser plate is preferably connected in a heat-conducting manner to the boundary wall of the feed line.
  • the difforsor plate is therefore also heated by the feed line, more precisely by the steam flowing in the feed line. Water droplets that still hit the diffuser plate are then evaporated very quickly. It is thereby achieved that the steam chamber is heated on all sides or at least on four sides from the feed line. This enables a relatively uniform temperature distribution to be produced inside the steam chamber.
  • the diffuser plate and / or the baffle plate is advantageously formed from a material which has approximately the same thermal expansion coefficient but a significantly better thermal conductivity with respect to the material of the boundary wall of the feed line.
  • the thermal conductivity may well be a factor of 10 or more above the thermal conductivity of the material of the boundary wall of the feed line.
  • This construction has the advantage that the connections between the diffuser plate or the baffle plate and the boundary wall of the feed line are kept low on the one hand by thermal stresses.
  • the high thermal conductivity ensures that the diffuser plate or the baffle plate is always kept at a relatively high temperature, in particular above 100 ° C., which is practically the same as the temperature of the steam flowing in the feed line.
  • the diffuser plate radiates heat to the outside.
  • heat is supplied from the supply line here.
  • the diffuser plate and / or the baffle plate is made of copper, while the boundary wall of the feed line consists essentially of stainless steel.
  • Copper and stainless steel have essentially the same coefficient of thermal expansion, which is also referred to as the linear expansion coefficient ⁇ .
  • copper has a coefficient of thermal conductivity ⁇ that is 10 to 37 times greater than that of stainless steel, for example chromium-nickel steel or chromium steel 5% Cr. With this combination of materials, mechanical durability can be ensured, but also the desired temperature distribution.
  • the housing of the steam chamber can also be provided with heating channels which are connected to the inside of the feed line and through which steam can flow. This configuration does require additional heating channels. However, very specific heating of certain parts of the steam chamber can be realized.
  • the nozzles are preferably formed by bores which are arranged in at least two rows which are offset from one another in such a way that in the running direction of a material web to be moistened there is a bore in one row in front of or behind a gap between bores in another row.
  • the bores as seen in the direction of travel of the material web, can be arranged close to one another without the dense arrangement disadvantageously reducing the mechanical strength.
  • the nozzles can be designed as slot nozzles. This also ensures that the steam is applied uniformly over the entire width of the material web.
  • the nozzles are grouped together in zones, nozzles of one zone being fed by a common steam chamber, which is separate and separately controllable from steam chambers of other zones. It is therefore only necessary to control the steam pressure or the amount of steam in individual steam chambers, which is expediently carried out via the valve assigned to the steam chamber in order to change the steam application from a nozzle zone.
  • the smoothness or gloss can be regulated or controlled in the transverse direction of the material web.
  • nozzle arrangements of adjacent zones are arranged to overlap one another.
  • the nozzles of each zone can generally not be brought right up to the edge, so that with a simple arrangement of the zones gaps would appear side by side between individual zones, which would be noticeable by stripes in the gloss or smoothness. This negative effect can be avoided by the fact that individual nozzle arrangements are now overlapping.
  • the overlap can be achieved in particular in that the rows enclose an acute angle with respect to the direction of the longitudinal extension of the feed line.
  • the individual nozzle arrangements are therefore not completely offset forwards or backwards in the running direction. They are not at right angles to the running direction of the material web, but rather at an angle, so that the material web can be moistened very uniformly. The moistening takes place essentially at the same distance from the roll gap, based on the width of the material web.
  • the angle is preferably adjustable. This allows the width of the overlap between adjacent zones to be changed and set to a desired value.
  • the nozzles preferably have a diameter which is smaller than their length. A steam flow emerging from the nozzles can thus be generated, which has a relatively high speed and is also still directed. It is thereby achieved that the air layer adhering to the material web can be torn open even better and the material web can be moistened accordingly.
  • the object is achieved in a method of the type mentioned above in that a constant vapor pressure is set together for all zones of at least one material web side, and with a difference between the setpoint and actual value in the machine direction The degree of opening of the valves of all zones is changed by the same value, the valves being designed as analog and linearly controllable, in particular linear, valves.
  • the steam pressure is set once depending on the material to be processed and other machine parameters. It can then be left practically unchanged. It is set so that a normally satisfactory result is achieved with a medium opening of the valves. Only when there are deviations from gloss or smoothness in the machine direction are all the valves opened or closed evenly, and the linearity of the valve behavior means that very simple control can be achieved. Due to the linear dependency, no complicated conversions with regard to the degree of opening occupied before actuation of the valve have to be carried out in the valve control. Rather, when the control signal for the individual valves is reduced or increased, it must be assumed that the amount of steam emitted is correspondingly, ie proportionally, reduced or increased.
  • the linear valve behavior can be realized particularly easily by means of linear valves, ie with analog valves, the flow rate of which is directly proportional to the control signal. Such valves are also referred to as equal percentage valves.
  • the linear valve function can also be implemented by connecting a conversion unit that takes into account the valve characteristic curve, ie the dependence of the flow rate on the degree of opening. In many cases, this dependency follows the natural logarithm.
  • the linear valve behavior makes it possible to decouple individual parameters, for example gloss and / or smoothness values in the machine direction or in the cross-machine direction, relatively well from one another, because they are assigned to the individual parameters Superimpose steam quantities linearly. This also makes it easier to take into account the dependency on other zones.
  • the valves of the individual zones are preferably adjusted independently of one another and only as a function of the difference assigned to the own zone. This also enables regulation or control of gloss or smoothness in the cross machine direction, that is to say transversely to the running direction of the material web, to be achieved. Again, the linear behavior of the valves is advantageous. If, for example, 5% more steam is required due to a deviation, the valve is opened further without having to take into account a dependency on the position previously assumed.
  • the amount of steam emitted is increased or decreased essentially independently of the actual values determined in accordance with a predetermined function.
  • accelerating or decelerating the web which is always the case, for example, when material web rolls are calendered, because the calender must be accelerated at the beginning of the web until it is at full working speed and then braked again at the end, this results in a constant one
  • Applying steam increases the gloss or smoothness values beyond a desired level. This increase, however, cannot be detected or can only be detected inadequately by the usual sensors which move across the width of the material web.
  • the specified function preferably describes a linear dependence on the time or the speed of the path.
  • the simplest embodiment is the linear dependence on time. Although this does not give quite as good results because the increase in speed of the web is rarely strictly linear, the control effort is relatively low. Better results are achieved if the amount of steam is made dependent on the speed of the web. In this case, however, the processing of a speed signal is additionally required.
  • the change in the amount of steam is initiated as a function of a signal initiating the change in speed of the web.
  • a signal can be obtained from the calender control.
  • This signal instructs the drive motors of the calender to accelerate or decelerate the calender or the nip arrangement. Since the behavior of the roll nip arrangement is known, that is to say the time after which a change in speed occurs after this signal, this signal can also be used for steam control, more precisely for initiating the change in the quantity of steam emitted.
  • At least part of the steam is applied in front of the first nip, in particular from both sides of the material web at the same time.
  • the greatest change in the surface takes place in the first roll nip or in the first roll nips.
  • the applied moisture supports this change in the With regard to improved gloss and / or smoothness values, so that overall better results can be achieved by applying the moisture before the first nip.
  • steam is applied to one side of the material web by at least two steam spray pipes. In this case, you have greater freedom to control the amount of steam applied.
  • one of the steam spray tubes can be controlled to compensate for differences between set and actual values in the machine direction, while another is controlled to compensate for differences in the cross-machine direction. This simplifies the control considerably, especially in the case of linearly operating valves, because the steam quantities superposition linearly.
  • one of the steam spray tubes can be used for a coarse adjustment and another for a fine adjustment of the amount of steam dispensed. This allows a very precise adjustment of the amount of steam to be achieved.
  • a steam spray pipe can be switched on after the capacity limit of another pipe has been reached.
  • the capacity of a steam pipe i.e. the maximum amount of steam that can be dispensed, can thus be kept within relatively narrow limits, which makes dimensioning easier.
  • a quotient of the difference and the maximum value of smoothness and / or gloss is advantageously formed, and the amount of steam emitted is increased or decreased by an amount that results from the multiplication of the quotient by the maximum dispensable amount of steam results.
  • the amount of steam is so to speak linearly tracked the gloss and or the smoothness.
  • the amount of steam in at least one other zone is preferably changed with a correspondingly reversed sign in order to keep the total amount of steam emitted constant.
  • amount of steam naturally refers to the amount of steam delivered per unit of time.
  • the smoothness and / or gloss overall is kept the same by the compensation. Otherwise, increasing or decreasing the amount of steam in a zone could increase or decrease the average gloss and / or smoothness.
  • the amount of steam changed with the opposite sign is distributed over several zones. This avoids extreme value formation. The change in the amount of steam distributed over several zones is not so noticeable.
  • a predetermined minimum amount of steam and / or maximum amount of steam is set for all zones depending on the material of the material web.
  • These amounts of steam can be stored, for example, together with the target value specified for the material web.
  • the minimum amount of steam shortens the start-up time and thus the waste of material.
  • the amount of steam will brought close to the value that ensures the desired gloss and / or smoothness value. By limiting the amount of steam to a maximum value, the material is protected. With coated papers in particular, too much steam can cause the coating to come off.
  • a particularly advantageous embodiment is one in which the difference in the amount of steam emitted from adjacent zones is limited to a pre-ordered maximum value. On the one hand, this reduces the load on the rolls of the roll nip device. On the other hand, glossy or smooth streaks are avoided. The material web gets a more uniform appearance.
  • a calender 1 has a plurality of work rolls 2, between which roll gaps 3 are formed.
  • a material web 4 is guided through the roll nips 3, for example a paper web, which is guided over deflection rollers 5 after each passage through a roll nip.
  • a deflecting roller 5 and a roller nip 3 following in the web running direction 6 an essentially rectilinear section 7 of the material web 4 is created, on the underside of which a steam spray tube 10 is arranged.
  • Another steam spray tube 10 ' is provided for the other side of the material web. Both steam spray tubes 10, 10 'can be of the same design.
  • the steam spray pipe 10 is connected to a steam source 12 via a steam transport line 11. Furthermore, the steam spray pipe 10 is connected to a control device 14 via a signal line 13. The control device 14 is in turn connected to a measuring device 15, which determines the gloss or smoothness of the surface of the material web 4 behind the last roller of the calender 1 and reports it back to the control device 14. The control device 14 now compares the determined actual value of gloss or smoothness of the material web 4 with a predetermined desired value and changes the amount of steam emitted via the steam spray pipe 10 as a function of the difference between the actual and desired values.
  • steam spray tubes 10A, 10A 'and 10B, 10B' can also be provided.
  • the steam spray pipes with the painted sizes are responsible for the upper side of the material web 4, while the others act on the lower side of the material web. All steam spray pipes 10, 10A, 10B or 10 ', 10A', 10B 'can be fed by the respective control devices 14, 14' or by the respective steam sources 12, 12 '.
  • the steam spray pipes 10B, 10B ' are arranged opposite one another, so that the steam spray pipe 10B' is arranged "overhead". This can only be realized if, as in the illustrated exemplary embodiments of the steam spray pipes, the transport of water droplets onto the material web 4 can be reliably avoided.
  • the application of moisture to the material web 4 in front of the first nip 3 of the calender 1 has the effect that already in the first nip 3 the necessary deformation work in the surface of the material web 4 with the support of the moisture, which may plasticize the surface or the entire material web to a certain extent, can be supported.
  • Fig. 2 shows the detailed structure of a first embodiment of such a steam spray pipe 10, in which the steam transport line 11 opens into a feed line 16.
  • the feed line 16 is provided in a housing 17 which is at least partially surrounded by a heat protection cover 18.
  • a valve 19 is arranged in the interior of the housing 17, more precisely, its valve seat 20 and its closure piece 21.
  • the valve 19 has a drive part 22 which is arranged outside the housing 17.
  • the drive part is connected to the housing 17 with the interposition of thermal insulation 23, for example in the form of a disk made of plastic which is not or very poorly thermally conductive, so that little or no heat is transferred from the housing 17 to the drive part 22.
  • the valve 19 can be actuated pneumatically.
  • it has a pressure chamber 24 which is enclosed by the drive housing 25 and a membrane 26.
  • the membrane is loaded on the side facing away from the pressure chamber 24 by a spring 27.
  • the closure piece 21 is connected to the membrane 26 via a drive rod 28 which is sealed in the drive housing 25 with the aid of seals 29, so that the closure piece 21 is also moved when the membrane 26 moves.
  • the pressure in the pressure chamber 24 is set with the aid of a pneumatic valve arrangement 30, which is only shown schematically.
  • the valve 19 is designed as a so-called linear valve. This means that the one let through the valve 19 The amount of steam is linearly dependent on a signal supplied to the drive part 22, for example the air pressure supplied to the drive part 22. If the signal responsible for the actuation of the valve is increased in value by 10%, the valve 19 also lets through 10% more steam, regardless of which position the valve 19 had previously been. Of course, this does not apply to limit value situations in which the valve 19 can no longer open or close.
  • the housing 17 is bent inwards on its side facing the material web 4 and has a U-shaped recess 31 with its open end facing the material web, which is closed by a diffuser plate 32.
  • nozzles 33 are provided, which are arranged in two rows, the two rows of nozzles being offset from one another in the transverse direction of the material web such that the nozzles 33 of a row in the running direction 6 of the material web 4 are in front of or behind a gap between nozzles 33 another row.
  • the housing 17 and the diffuser plate 32 together enclose a steam chamber 34.
  • the nozzles 33 and the steam chamber 34 together form a nozzle arrangement.
  • the steam chamber 34 is supplied with steam from the supply line 16 via the valve 19.
  • an essentially rectilinear acceleration channel is provided, in which a nozzle channel 36 branches off from a predetermined distance towards its end 37.
  • the end 37 of the acceleration channel 35 is closed off by a baffle plate 38, at the lowest point of which in the direction of gravity there is an opening 39 designed as a throttle, via which the acceleration channel 35 is connected to a disposal channel 40.
  • a baffle plate 41 is arranged in the steam chamber 34, namely in the extension of the nozzle channel 36, so that the direct path from the nozzle channel 36 to the nozzles 33 is blocked.
  • the steam emerging from the nozzle channel 36 must therefore change its direction of movement at least once before it reaches the nozzles 33.
  • the nozzles 33 have a length that is greater than their diameter. This allows a directed steam jet to be generated.
  • the diffuser plate 32 and the baffle plate 41 are welded to the housing 17 or connected to one another in a heat-conducting manner in some other way.
  • the diffuser plate 33, but also the baffle plate 41 have the same linear thermal expansion coefficient as the housing 17. This can be used, for example, for the diffuser plate 32 and the baffle plate 41 at 17 x 10 -6 m / (mK) and for the housing 17 at 16 x 10 -6 m / (mK) lie.
  • the thermal conductivity of the diffuser plate 32 is, however, much greater than that of the housing 17. For example, it is approximately 380 W / (mK) in the case of the diffuser plate 32 and the baffle plate 41, while it is 10 ... 15 W / (mK in the case of the housing ) lies.
  • Such a pairing of materials can be realized, for example, by using copper for the diffuser plate 32 and the baffle plate 41 and using chromium-nickel steel or another stainless steel for the housing 17.
  • the steam spray pipe 10 works as follows:
  • the supply line 16 is permanently flowed through by steam at a predetermined pressure.
  • the valve 19 is opened to a value specified by the control device 14.
  • the steam can now flow from the feed line 16 into the acceleration channel 35. Any water droplets present in the steam naturally also flow through the valve 19.
  • the water droplets that have become relatively slow due to the change in direction when passing through the valve (based on the direction of movement of the steam) are now accelerated in the acceleration channel 35.
  • the steam is now directed or deflected at right angles into the nozzle channel 36, which is arranged at a considerable distance, in the present case almost half the length of the acceleration channel, in front of the end 37 of the acceleration channel 35.
  • the water droplets which are now at a considerable speed, cannot take part in this rapid change of direction. They continue to fly straight ahead and either hit the baffle plate 38 or previously hit the lowest point in the direction of gravity at the end 37 of the acceleration channel 35.
  • the resulting water accumulation can flow through the opening 39 into the disposal channel 40.
  • the draining water clogs the opening 39 so that no significant steam losses occur here.
  • the opening 39 is not used for the discharge of water into the disposal channel 40, it is designed as a throttle, that is, it opposes the steam a certain flow resistance, so that the majority of the steam flowing through the valve 19 except for a negligible rest can also exit through the nozzles 33.
  • the acceleration channel 35 is arranged in a housing 42 that is located entirely in the interior of the housing 17, ie in the feed line 16.
  • the housing 42 thus has the temperature of the flowing in the feed line 16 Steam. It is therefore hot enough to be able to evaporate water drops.
  • the steam can be fed into the steam chamber 34 at a relatively high pressure, where it spreads evenly and with uniform pressure through all the nozzles 33 of a nozzle arrangement which this steam chamber 34 is assigned, can flow out. Due to the relatively high pressure in the steam chamber 34, the steam can develop at a relatively high speed when it flows out through the nozzles 33, so that it or the mist it develops in the ambient air also at high speed or with high pressure on the material web 4 hits.
  • the air layer adhering to the material web is torn open, and the water in the mist can precipitate on the material web 4, so that the material web 4 is provided with sufficient moisture to obtain the desired smoothness or the desired gloss in the subsequent nip 3.
  • the risk that water droplets emerge through the nozzles 33 and lead to damage to the material web 4 is so extremely low that it is practically negligible.
  • the steam speed can therefore be increased considerably compared to conventional pipes, so that higher material web speeds can also be permitted.
  • FIG. 5 shows a top view of a steam spray pipe 10, from which it can be seen that each steam spray pipe 10 has a plurality of nozzle arrangements 33 arranged in zones.
  • the nozzles 33 are arranged in rows 43 which enclose an acute angle with the cross machine direction, that is to say a direction transverse to the material running direction. This makes it possible for nozzle arrangements 33 of adjacent zones to overlap one another. At the boundary between two zones, this also ensures that the passing material web is subjected to a sufficient amount of steam.
  • the transport line 11 for steam can be guided in a ring, so that the steam flowing through the steam spray pipe 10, which is not used, or condensed water is returned to the steam source 12. This ensures that the steam is always at the required temperature.
  • the steam spray tube including all parts contained in it and around which the steam flows, can also be heated before the actual start of operation. so that even at the start of operation there are no irritating water droplets have deposited on cooled parts of the steam spray tube 10, interfere.
  • each zone has its own valve, of which only the drive parts 22 and the valve arrangements 30 can be seen.
  • a steam pressure is set for operation, which then prevails in the feed line 16.
  • This vapor pressure is usually not changed during operation. It depends on the calender 1 or on the web 4 to be treated.
  • the gloss or smoothness values are determined by the measuring devices 15, 15 'and reported back to the control devices 14, 14'. These then adjust the degree of opening of the valves 19 so that the desired gloss or smoothness value of the material web is achieved. If the results obtained deviate from the specified values, the valves 19 are changed accordingly, this change being able to take place zone by zone if there is a deviation transversely to the material web running direction, or jointly for all valves 19 if there is a deviation in the machine running direction . For example, in the latter case, all valves can be opened evenly by 10% to dispense a 10% larger amount of steam. This is particularly easy due to the use of linear analog valves in the control.
  • FIG. 4 shows a second embodiment of a steam spray tube, in which the same parts are provided with the same reference symbols and corresponding parts are provided with 100 reference symbols.
  • the U-shaped recess 131 of the housing 117 is wider in this embodiment, so that it no longer directly encloses the steam chamber 134. Rather, the steam chamber 134 is in a separate block 44 arranged, which is screwed onto the housing 117 or a part firmly connected to it, such as the housing 42 of the acceleration channel 35.
  • steam channels 45, 46 are provided, which are connected to the feed line 16 via an auxiliary channel 47 and are supplied with hot steam from there. With the help of the steam channels 45, 46, the block 44 is heated so that the steam chamber 134 is surrounded on all sides by heated walls.
  • the steam channels 45, 46 are permanently flowed through by the steam, i.e. at their end they have steam outlets, not shown, from which the steam can optionally be fed back to the steam source 12.
  • the nozzle channel 36 opens tangentially into the steam chamber 134.
  • the nozzles 133 are laterally offset such that they lie outside the projection of the mouth of the nozzle channel 36 onto the wall of the steam chamber 134. In this case, too, no steam can reach the nozzles 133 in a directed manner from the nozzle channel 36. Rather, it is necessary that the steam first spreads out in the steam chamber 134 before it can pass through the nozzles 133.
  • siphons 48, 49, 50 are also provided at the lowest points in the direction of the force of gravity, with the aid of which water accumulating can be disposed of in a known manner.
  • FIG. 6 shows a cross section through a further steam spray tube 210, in which parts which correspond to those from FIG. 2 are provided with the same reference numerals and corresponding parts with 200 reference numerals increased.
  • baffle plate 241 Only the baffle plate 241 has changed, which is no longer perpendicular to the direction of the intermediate channel 36, but is inclined to it.
  • the baffle plate 241 thus forms an inclined plane with respect to the incoming steam from the nozzle channel 36, so that the steam is practically inevitably directed onto the right wall of the steam chamber 234 shown in FIG. 6. This is the wall that faces the valve 19, so that it is ensured that there is always a certain steam flow through the feed line 16. So this wall will always be hot. Only a negligible part of the steam will reach the opposite wall.
  • the baffle plate 241 is also no longer connected to the side walls of the steam chamber 234, as in FIG. 20, but rather via its own side walls 48 to the bottom of the steam chamber 234, that is to say to the surroundings of the mouth of the nozzle channel 36.
  • FIG. 7 shows that the side walls 48 open to the said steam chamber wall, so that there is an even further alignment of the steam towards the side wall.
  • the inclination of the baffle plate ensures that the water, which may still form, is in an area of the Diffuser plate 32 drips, which lies outside the nozzles 33. Since the diffuser plate formed from copper always has the temperature of the steam flowing in the feed line 16, ie is hotter than 100 ° C., the water dripping onto the diffuser plate 32 will evaporate immediately and can therefore no longer escape through the nozzles 33.
  • the right of the two zones shown has the nozzles 33 in two rows.
  • the left of the two shown Zones has a slot nozzle 233 from which the steam can also emerge relatively evenly.
  • the slot width is smaller than the thickness of the diffuser plate 32.
  • Fig. 8 how the amount of steam Qmenge is controlled will now be explained.
  • the length of the material web to be treated is applied to the right and upward gloss or smoothness G, the speed v and the amount of steam emitted Q ⁇ .
  • the beginning of the material web is first threaded through a calender.
  • the calender is then accelerated so that the speed of the material web increases according to curve v.
  • the material web reaches its working speed, which is then kept as constant as possible.
  • the speed Shortly before the end of the lane, namely at point B, the speed must be reduced again so that the treatment can be completed properly and no dangerous situations arise.
  • the amount of steam Qmenge is influenced independently of the signals from the sensors 15, 15 'because these generally traverse across the width of the material web and are therefore too slow to detect changes in gloss and / or smoothness due to a change in the material web speed.
  • the amount of steam can also be adjusted depending on the time or speed of the web.

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  • Paper (AREA)
  • Treatment Of Fiber Materials (AREA)
EP94103979A 1993-03-20 1994-03-15 Dampfsprührohr und Verfahren zum Einstellen von Glanz und/oder Glätte einer Materialbahn Expired - Lifetime EP0618328B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4309076 1993-03-20
DE19934309076 DE4309076C2 (de) 1993-03-20 1993-03-20 Dampfsprührohr

Publications (2)

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EP0618328A1 EP0618328A1 (de) 1994-10-05
EP0618328B1 true EP0618328B1 (de) 1996-12-11

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US (2) US5429303A (ja)
EP (1) EP0618328B1 (ja)
JP (1) JP2611140B2 (ja)
CA (1) CA2116603C (ja)
FI (1) FI106809B (ja)

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DE19858839B4 (de) * 1998-12-19 2005-02-10 Babcock Textilmaschinen Gmbh Verfahren und Vorrichtung zum Wärmebehandeln einer durchlaufenden Warenbahn durch Aufblasen von Dampf
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FI111472B (fi) * 2002-02-13 2003-07-31 Metso Paper Inc Menetelmä paperirainan kosteusprofiilin säätämiseksi
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Also Published As

Publication number Publication date
EP0618328A1 (de) 1994-10-05
FI106809B (fi) 2001-04-12
US5445071A (en) 1995-08-29
CA2116603C (en) 1997-09-23
CA2116603A1 (en) 1994-09-21
FI941248A0 (fi) 1994-03-16
JPH06306792A (ja) 1994-11-01
US5429303A (en) 1995-07-04
JP2611140B2 (ja) 1997-05-21
FI941248A (fi) 1994-09-21

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