EP2165019A1

EP2165019A1 - Method and device for moistening a material web

Info

Publication number: EP2165019A1
Application number: EP08735945A
Authority: EP
Inventors: Jörg Spindler
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2007-05-31
Filing date: 2008-04-08
Publication date: 2010-03-24
Also published as: WO2008145447A1; US20100084104A1; CA2689367A1; US8029648B2; DE102007025611A1

Abstract

In a method for moistening a material web (12), particularly a moving web, particularly a paper or cardboard web, the moisture is applied onto the material web (12) via at least two medium flows (14, 16) of different temperatures, particularly two vapor flows, or one vapor flow and one gas flow.

Description

Method and device for moistening a material web

The invention relates to a method and a device for moistening a particular moving material web, in particular paper or board web.

It is already known to use steam boxes and steam dampers on a calender for influencing the quality properties of the paper produced, in particular for influencing gloss, smoothness and moisture in the machine direction and in the transverse direction. However, when moisture is applied by pure steam, the amount of moisture applied is limited.

In a spraying device known from the document WO 2007/003059 A1, condensate is added to the steam in order to increase the total amount of moisture applied to the material web in the region of a calender within a special nozzle. Although such a spraying device can be used for cross profiling. However, it tends to drip and to a very rapid clogging of the condensate lines, as they must be designed very thin to avoid water droplets. Particularly critical here are so-called overhead installations.

In one known from the document DE 29 25 026 A1 method for moistening webs of water is added to the steam at the exit from the nozzles. According to the publication WO 2004/063463 A1, the material web is acted upon by a steam blower box and additionally with water. Also in this case, among other things, there is again the danger of droplet formation.

The invention has for its object to provide an improved method and an improved device of the type mentioned, in which the aforementioned disadvantages are eliminated. In particular, a zone-wise application of moisture to a moving material web, in particular paper or board web, before and / or within a calender for influencing moisture, gloss and / or smoothness in the transverse and / or longitudinal direction is to be made possible.

With regard to the method, this object is achieved in that the moisture is applied to the material web via at least two medium streams of different temperature. The at least two medium streams may comprise two vapor streams or a vapor stream and a gas stream.

Since the two medium streams of different temperature have different sized moisture units or droplets, it is possible to give the material web, in particular paper or board web more moisture.

The moisture cross profile, the moisture longitudinal profile and / or the moisture level of the material web are preferably influenced by the medium streams of different temperature.

It is particularly advantageous if the moistening of the material web takes place zone-wise, viewed transversely to the web running direction, and the moisture to be applied to the material web in a respective zone is applied in each case via at least two medium streams of different temperature. For the relatively higher temperature owning medium flow, in particular steam flow, superheated steam is expediently used.

According to a preferred practical embodiment of the method according to the invention, the temperature of a respective medium stream of relatively higher temperature is at least substantially constant and / or the temperature of the medium streams of relatively higher temperature distributed over the zones is at least substantially the same.

Preferably, the temperature of the medium flow having the relatively lower temperature is separately variable for each zone, thereby enabling a corresponding profiling.

A preferred practical embodiment of the method according to the invention is characterized in that the two medium streams, in particular

Steam streams, different temperature from a common supply, in particular steam supply, are fed and one of the two

Medium streams, in particular steam streams, is cooled. In this case, the relevant medium flow, in particular steam flow, are advantageously changed by the cooling in the region of saturated or wet steam.

The amount of moisture to be applied in each case to the material web is advantageously set and / or regulated via the cooling of the relevant medium flow.

According to an expedient practical embodiment of the method according to the invention, the medium stream in question is cooled directly. For such a direct cooling of the respective medium flow condensate is advantageously introduced into the medium flow. In this case, the amount of condensate to be introduced is preferably controlled via a metering device. However, according to an expedient alternative embodiment, the relevant medium flow can also be cooled indirectly. Such indirect cooling is expediently carried out via at least one heat sink with a separate coolant circuit. The coolant is expediently metered in via a metering device in the desired manner.

To influence certain properties of the material web, the amount of medium flow of relatively higher temperature and / or the amount of medium flow of relatively lower temperature is advantageously additionally varied. In particular, such properties as the moisture, gloss and / or smoothness according to the "iron principle" can be influenced in particular again.

According to a preferred practical embodiment of the method according to the invention, the two medium streams of different temperature are combined within a nozzle and applied to the material web via such a nozzle.

According to an alternative advantageous embodiment, however, the two medium streams of different temperature can be mixed even after leaving a respective nozzle before they impinge on the material web.

The moistening device according to the invention is correspondingly characterized in that it comprises a steam humidifier for applying the moisture over at least two medium streams of different temperature. The at least two medium streams may comprise two vapor streams or a vapor stream and a gas stream.

Preferred embodiments of the device according to the invention are specified in the subclaims. Of particular advantage is a use of the method and / or the device according to the invention for influencing the moisture, gloss and / or smoothness of a material web, in particular paper or board web, in particular before and / or within a calender. In this case, again a profiling in the transverse and / or longitudinal direction is conceivable.

The zonal application of the moisture can therefore be effected by means of two differently tempered medium streams, in particular steam streams. The higher-tempered medium flow, preferably superheated steam, can be left constant in its temperature. The second medium flow, which may be fed by the same supply line as the first medium flow of higher temperature, can be changed separately for each zone by suitable cooling, in particular into the saturated and wet steam. In this case, the relevant cooling element can be used to control the order quantity.

The two medium streams can be applied together by merging within a nozzle on the material web. The current of higher temperature or the superheated current can be used as a carrier medium for the other stream or wet steam, thereby avoiding droplet formation on the steam humidifier.

Alternatively, the two medium streams can be mixed after exiting a nozzle before they hit the web. The different media streams have different sized humidity units, that is. Droplets, whereby the web more moisture can be given.

The aforementioned cooling can be direct or indirect. The direct cooling can be done by introducing condensate, which is controlled by a suitable metering device. The indirect cooling can be done by a heat sink, which is provided with a separate cooling circuit and especially how a heat exchanger works. In this case, the cooling liquid used in the cooling circuit can be precisely metered.

In addition, both the amount of the first medium flow of higher temperature and the amount of the medium flow of lower temperature can be varied in both types of cooling in order to optimize the qualities of the material web or paper qualities. Again, a suitable metering device is appropriate.

For optimum control, various sensors for pressure and temperature measurement as well as optionally also optical sensors can be used in order to be able to draw conclusions on the droplet size and / or the water content on the basis of the so-called vapor analysis.

By eliminating the risk of blockage of smaller holes, the availability is increased accordingly. In addition, the dosage is simplified. Instead of the hitherto customary combination of steam and water or air and water, two different medium flows are used according to the invention. In particular, the cooling of one of the two medium streams for zonal adjustment of the respective qualities of the material web or for the zonal adjustment of the respective paper qualities such as in particular moisture, gloss and / or smoothness can be used, in particular in the transverse and / or longitudinal direction.

The invention will be explained in more detail below with reference to exemplary embodiments with reference to the drawing; in this show:

Fig. 1 is a simplified schematic representation of an exemplary

Embodiment of a humidification device according to the invention, in which the two vapor streams of different temperature are brought together within a nozzle; FIG. 2 shows a more detailed schematic illustration of a further exemplary embodiment of the moistening device, in which the two vapor streams of different temperature are brought together again within a nozzle; FIG. and FIG. 3 shows a more detailed schematic representation of a further exemplary embodiment of the moistening device, in which the two vapor streams of different temperature are mixed after exiting a respective nozzle.

1 shows, in a simplified schematic illustration, an exemplary embodiment of a device 10 for moistening a material web 12, in particular a moving material web 12, which may in particular be a paper or board web.

The humidifying device 10 comprises a steam humidifier 18 for applying the moisture via two steam streams 14, 16 of different temperature, over which in particular the moisture transverse profile, the moisture longitudinal profile and / or the moisture level of the material web 12 can be influenced.

In the present description of the figures, the two medium streams 14, 16 are purely by way of example two vapor streams. However, in a further embodiment, they can also be a vapor stream and a gas stream or the like, which fully meet the requirements placed on them.

In this case, the steam humidifier 18 can be embodied in particular for a zone-wise moistening of the material web 12 viewed transversely to the web running direction L. In this case, the moisture to be applied to the material web 12 in a respective zone can be applied in each case via at least two such vapor streams 14, 16 of different temperature.

The first vapor stream 14 having the relatively higher temperature can in particular be formed by a stream of superheated vapor. The moistening device 10 may in particular be designed such that the temperature of a respective vapor stream 14 of relatively higher temperature is at least substantially constant and / or the temperature of the vapor streams 14 of relatively higher temperature distributed over the zones is at least substantially the same.

In contrast, the temperature of the relatively lower temperature owning second vapor stream 16 is preferably variable. In the preferred design of the steam humidifier 18 for zone-wise moistening of the web 12, the temperature of the second vapor stream 16 having the relatively lower temperature is separately variable for each zone.

As can be seen with reference to FIG. 1, the two steam streams 14, 16 of different temperature can be supplied from a common steam supply 20 and a device 22 for cooling one of the two steam streams, in this case the steam stream 16, can be provided. The temperature of the uncooled

In particular, steam in the common steam supply 20 and corresponding to the steam of the first relatively high temperature steam stream may be in a range of about 115 to about 125 ^° C.

The second vapor stream 16 can be changed via the cooling device 22 expediently in the region of saturated or wet steam.

The cooling device 22 may be provided for direct or indirect cooling of the second vapor stream 16.

As can be seen with reference to FIG. 1, in the present case the two steam streams 14, 16 of different temperature are brought together, for example, within a single nozzle 24, in particular a spray nozzle, and the material web is acted upon via this nozzle 24. FIG. 2 shows in a more detailed schematic representation a further exemplary embodiment of the moistening device 10, which in principle is again constructed in the same way as the device according to FIG. 1. Parts corresponding to one another are assigned the same reference numerals. In this case, the two vapor streams 14, 16 of different temperature are again brought together within a nozzle 24 in the present case, via which then the material web 12 is acted upon accordingly.

As can be seen from FIG. 2, the moistening device 10 comprises a control device 26, for example in the form of a control computer, with a plurality of inputs 28 for connecting various sensors 30 to 38 and a plurality of outputs 40 to 44, in particular for acting on different actuators.

As already mentioned, the cooling device 22 can be provided for direct or indirect cooling of the second vapor stream 16 of relatively lower temperature.

In the case of direct cooling of the steam flow 16, for example, a condensate injection may be provided. Here is, for example, a

Metering device 46 is provided, can be introduced via the condensate in the vapor stream 16. The metering device 16 can be used for adjustment or

Regulation of the flow rate of the condensate with the output 42 of the

Control device 26 may be connected. The amount of condensate to be introduced is thus controllable via the metering device 46 in this case.

In the case of indirect cooling of the second vapor stream 16, the cooling device 22 may comprise at least one cooling body with a separate coolant circuit. In this case, the coolant, for example cooling water, can be dosed correspondingly via a metering device 48. For this purpose, in this case, this metering device 48 with the output 42 of the control device 26th be connected. About the metering device 48, the flow rate of the respective coolant can then be adjusted or regulated.

For influencing certain properties of the material web 12, in particular for influencing moisture, gloss and / or smoothness, the amount of vapor stream 14 of relatively higher temperature and / or the amount of vapor stream 16 of relatively lower temperature can additionally be varied. For example, an actuator influencing the steam flow 14, such as e.g. a pressure adjusting element 50 and / or an actuator influencing the steam flow 16, such as e.g. a pressure adjusting element 52 may be provided. As can be seen with reference to FIG. 2, the pressure adjustment element 50 can be connected, for example, to the output 44 and the pressure adjustment element 52 can be connected to the output 40 of the control device 26, for example.

The Druckeinstellelemente 50, 52 are, as already mentioned, optional and can be used zonal or global, for example.

For the two vapor streams 14, 16, a common steam supply 20 is again provided, which supplies steam at the pressure P and the temperature T.

The inputs 28 of the control device 26 are partly with sensors 30 to 36 for measuring the pressure and / or for measuring the temperature of the steam in the common steam supply 20, the steam flow 14 relatively higher temperature or the steam in the nozzle 24 and the material web Provided 12 acting steam. As can be seen with reference to FIG. 2, the sensor 32 in the present case is provided in the region of the cooling device 22.

Optionally, one or more optical sensors 38 may be provided, for example by means of a vapor scan, one for each of the droplet size and / or the water content of the vapor streams and / or of the material web 12 supplying steam representative signal. In the present case, the optical sensor 38 serves to deliver a signal representative of the droplet size and / or the water content of the steam acting on the material web 12 to the control device 26.

The supply lines for the two vapor streams, the relevant actuators, the cooling device, the nozzle and / or the sensors are provided separately in the case of a zonal influence for each zone.

FIG. 3 shows in a more detailed schematic representation a further exemplary embodiment of the moistening device 10.

This humidifying device 10 differs from that shown in FIG. 2 essentially only in that the two vapor streams 14, 16 different temperature after exiting a respective nozzle 54 and 56 are mixed before they hit the material web 12.

Incidentally, this humidifying device 10 shown in FIG. 3 has at least substantially the same structure as that according to FIG. 2. Corresponding reference numerals are assigned to corresponding parts.

Finally, it should again be noted that in the present description of the figures, the two medium streams 14, 16 are purely by way of example two vapor streams. However, in a further embodiment, they may also be a vapor stream and a gas stream or the like. LIST OF REFERENCE NUMBERS

10 moistening device

12 material web

14 medium flow (vapor stream) relatively higher temperature

16 medium flow (vapor stream) relatively lower temperature

18 steam humidifiers

20 Common Supply

22 cooling device

24 nozzle

26 control device

28 inputs

30 sensor

32 sensor

34 sensor

36 sensor

38 sensor

40 output

42 output

44 output

46 metering device

48 dosing device

50 pressure adjustment element

52 pressure adjusting element

54 nozzle

56 nozzle

L web running direction

Claims

Method and device for moistening a web of material Patent claims

1. A method for moistening a particular moving material web (12), in particular paper or board web, characterized in that the moisture over at least two medium streams (14, 16), in particular two vapor streams or a vapor stream and a gas stream, different temperature on the web (12) is applied.

2. The method according to claim 1, characterized in that on the medium streams (14, 16) of different temperature the

Moisture transverse profile, the moisture longitudinal profile and / or the moisture level of the material web (12) are influenced.

3. The method according to claim 1 or 2, characterized in that the moistening of the material web (12) transversely to the web running direction (L) considered zonewise and that in a respective zone on the material web (12) to be applied moisture in each case via at least two medium streams ( 14, 16) of different temperature is applied.

4. The method according to any one of the preceding claims, characterized that superheated steam is used for the relatively higher temperature owning medium flow (14), in particular steam flow.

5. The method according to any one of the preceding claims, characterized in that the temperature of a respective medium flow (14) relatively higher temperature is maintained at least substantially constant and / or the temperature of the distributed over the zones medium streams (14) relatively higher temperature at least substantially is held equal.

6. The method according to any one of the preceding claims, characterized in that the temperature of the relatively lower temperature besitzenden medium flow (16) for each zone is separately variable.

7. The method according to any one of the preceding claims, characterized in that the two medium streams (14, 16), in particular steam streams, different temperature from a common supply (20), in particular steam supply, are fed and one (16) of the two

Medium streams (14, 16), in particular vapor streams, is cooled.

8. The method according to claim 7, characterized in that the respective medium flow (16), in particular vapor stream, is changed by the cooling in the region of saturated or wet steam.

9. The method according to claim 7 or 8, characterized in that each applied to the material web (12)

Moisture quantity is set and / or regulated via the cooling of the relevant medium flow (16).

10. The method according to any one of the preceding claims, characterized in that the medium stream in question (16) is cooled directly.

11. The method according to claim 10, characterized in that for the direct cooling of the respective medium flow (16) condensate is introduced into the medium flow (16).

12. The method according to claim 11, characterized in that the amount of condensate to be introduced via a metering device (46) is controlled.

13. The method according to any one of claims 1 to 9, characterized in that the respective medium flow (16) is cooled indirectly.

14. The method according to claim 13, characterized in that the indirect cooling takes place via at least one heat sink with separate coolant circuit.

15. The method according to claim 14, characterized in that the coolant via a metering device (48) is metered.

16. The method according to any one of the preceding claims, characterized in that for influencing certain properties of the material web (12) in addition, the amount of medium flow (14) relatively higher temperature and / or the amount of medium flow (16) of relatively lower temperature is varied.

17. The method according to any one of the preceding claims, characterized in that the two medium streams (14, 16) of different temperature within a nozzle (24) are brought together and the material web (12) via such a nozzle (24) is acted upon.

18. The method according to any one of claims 1 to 16, characterized in that the two medium streams (14, 16) of different temperature after leaving a respective nozzle (54 or 56) are mixed before they hit the web (12).

19. Device (10) for moistening a particularly moving material web (12), in particular paper or board web, in particular for carrying out the method according to any one of the preceding claims, characterized in that it comprises a steam humidifier (18) for applying the moisture over at least two Medium streams (14, 16), in particular two vapor streams or a vapor stream and a gas stream, different temperature.

20. The apparatus according to claim 19, characterized in that on the medium streams (14, 16) of different temperature, the moisture transverse profile, the moisture longitudinal profile and / or the moisture level of the material web (12) can be influenced.

21. Device according to claim 19 or 20, characterized in that the steam humidifier (15) is designed to moisten the material web (12) zone by zone, the moisture to be applied to the material web (12) in a respective zone in each case via at least two media flows (14, 16 ) of different temperature can be applied.

22. Device according to one of the preceding claims, characterized in that the relatively higher temperature owning medium flow (14), in particular vapor stream, is formed by a stream of superheated steam.

23. Device according to one of the preceding claims, characterized in that the temperature of a respective medium flow (14) relatively higher

Temperature is at least substantially constant and / or the temperature of the distributed over the zones medium streams (14) relatively higher temperature is maintained at least substantially equal.

24. Device according to one of the preceding claims, characterized in that the temperature of the relatively lower temperature besitzenden medium flow (16) for each zone is separately variable.

25. Device according to one of the preceding claims, characterized in that the two medium streams (14, 16), in particular steam streams, different temperature from a common supply (20) in particular steam supply, fed and means (22) for cooling one of the two medium streams (14, 16), in particular

Steam streams are provided.

26. The device according to claim 25, characterized in that the respective medium flow (16), in particular steam flow, via the cooling device (22) in the region of saturated or wet steam is variable.

27. The apparatus of claim 25 or 26, characterized in that it comprises a control device (26) in order to set and / or regulate the respective amount of moisture to be applied to the material web via the cooling of the respective medium flow (16).

28. Device according to one of the preceding claims, characterized in that the cooling device (22) for direct cooling of the relevant

Medium stream (16) is provided.

29. The device according to claim 28, characterized in that a metering device (46) is provided, via the direct

Cooling of the relevant medium flow condensate in the medium flow (16) can be introduced.

30. The device according to claim 29, characterized in that the amount of condensate to be introduced via the metering device (46) is controllable.

31. Device according to one of claims 19 to 27, characterized in that the cooling device (22) for indirect cooling of the respective medium flow (16) is provided.

32. Apparatus according to claim 31, characterized in that the cooling device (22) for indirect cooling comprises at least one heat sink with a separate coolant circuit.

33. Apparatus according to claim 32, characterized in that the coolant via a metering device (48) is metered.

34. Device according to one of the preceding claims, characterized in that for influencing certain properties of the material web (12) in addition, the amount of medium flow (14) of relatively higher temperature and / or the amount of medium flow (16) of relatively lower temperature is varied.

35. Device according to one of the preceding claims, characterized in that the two medium streams (14, 16) of different temperature within a nozzle (24) are brought together and the material web via such a nozzle (24) can be acted upon.

36. Device according to one of claims 19 to 34, characterized in that means are provided for mixing the two medium streams of different temperature after exiting a respective nozzle before they impinge on the material web.

37. Device according to one of the preceding claims, characterized that different sensors (30-36) for measuring the pressure and / or for measuring the temperature of the medium, in particular steam, in the common supply (20), in particular steam supply, at least one of the medium streams (14, 16), in particular steam streams, and / or of the material web (12) acting on medium, in particular steam, are provided.

38. Device according to one of the preceding claims, characterized in that one or more optical sensors (38) are provided, based on a vapor analysis in each case one for the droplet size and / or the water content of at least one of the medium streams (14, 16), in particular steam streams , And / or of the material web (12) acting medium, in particular steam, to provide representative signal.

39. Use of the method and / or the device according to one of the preceding claims for influencing the moisture, gloss and / or smoothness of a material web, in particular paper or board web, in particular before and / or within a calender.