DE202010017942U1 - Device for moistening the surface layer of a fibrous web - Google Patents

Abstract

Device for moistening a fibrous web (10), in particular a paper, tissue or board web, which is arranged in front of a nip forming the pair of rollers, with a steam blast chamber (6) arranged in a steam chamber (4) with a working steam connection (8) is and can be supplied with steam via at least one steam valve (3), characterized in that the steam - blowing chamber (6) is arranged in the steam chamber (4) such that at least part of an outer wall (15) provided with steam outlet openings (11) Steam blow chamber (6) is not enclosed by the steam chamber (4), wherein the outer wall (15) next to the steam outlet openings (11) with a heater (7) is independently heated.

Description

The invention relates to a device and method for moistening a fibrous web, in particular a paper, tissue or board web, which is arranged in front of a pair of rollers forming a nip. The device consists of a steam blast chamber, which is arranged in a steam chamber with a steam connection. The steam chamber can be supplied with steam via the steam chamber and at least one steam valve.

Such moistening devices serve to apply vapor to passing webs of material in order to increase their moisture and temperature. A widespread field of application here is the production or processing of paper webs in which such steam moistening devices are used in conjunction with calenders or other roll arrangements. The paper web is here before passing through a nip. steamed to improve the gloss or smoothness, to change the bulk, thickness or density, or to increase the humidity. Furthermore, the transverse profile can be improved via a transverse profile control.

The appearance of a paper web, which is mainly determined by the gloss and the smoothness or roughness of its surface, is in today's time an important parameter of the paper web. The surface texture not only affects its appearance, but also its further processability. For certain applications, high gloss and / or smoothness values are desired, which should also be reproducible as uniformly as possible.

To increase gloss and / or smoothness, the paper web is passed through at least one nip and smoothed under high pressure. Without additional pretreatment, the paper web would in this case be highly compressed and thus suffer a loss of volume. In addition, there is an increased black satin and a deterioration of the paper web properties.

Some designs of steam blow boxes are known from the prior art, it is z. B. in the DE 43 01 023 A1 discloses a steam box, which has a positioned between two working steam ducts steam chamber in which the free housing wall is heated via a heating channel. The heating steam for the heating channel is diverted from the working steam flow after flowing through the first working steam duct. As a result, no separate heating of the heating channel is possible and in the working steam ducts there is a relatively high flow rate.

Another moistening device is from the DE 41 25 062 A1 known. The steam box is similar here as the one from the DE 43 01 023 A1 , with the difference that the steam chamber is zoned. The zone partition walls are equipped with additional heating channels, so that each steam chamber can be heated on all sides. This structure is very expensive and brings in the heating of the free housing wall no advantage.

The DE 195 00 752 A1 discloses a Dampfbefeuchtungseinrichtung comprising a Heizdampfverteilerkammer over which the steam blower chamber is supplied with working steam. The even distribution is achieved through the supply lines. There is no heating of the free outer wall.

The object of the invention is to provide a device and a method for moistening a material web, which / does not have the disadvantages mentioned above and is also constructed more cost-effectively.

The object is achieved by means of a device having the features of claim 1 and the method according to claim 14.

According to the invention, a device of the aforementioned type is proposed in which the steam chamber is arranged in the steam chamber such that at least part of a steam outlet openings provided with the outer wall of the steam chamber is not enclosed by the steam chamber, the outer wall independently heated adjacent to the steam outlet openings with a heater is.

This ensures that the outer wall is always sufficiently heated with the steam outlet openings, so as to ensure that it does not come to a condensation in the evaporation chamber in particular when the plant recovers after a standstill.

The heating device is preferably formed by a heating channel which is connected from the outside to the outer wall and which is independently heated with steam.

Alternatively, an electric heater is conceivable, which is particularly advantageous controllable.

Furthermore, it is advantageous to heat the heating channel with separately supplied steam to ensure that sufficient steam is passed through the heating channel.

In a further embodiment of the device, a heating steam connection is provided for the heating channel, which is arranged on the opposite side of the working steam connection. This has the advantage that the heating channel is flowed through in countercurrent process with heating steam, whereby a particularly advantageous uniform heating of the outer wall takes place.

If the device is used for cross profile control, it is necessary to divide the steam blower box in the transverse direction to the running fibrous web in several zones, wherein the steam chamber is designed to be continuous over the entire width. Each zone can be supplied with steam from the steam chamber via a steam valve.

Each steam valve is preferably positioned on the steam chamber, such that the steam chamber can be connected to the steam blast chamber via the steam valve and a connection channel. By using a controllable valve, the z. B. is driven by a pneumatic or electric drive, the amount of steam is also still regulated by a quality control. Furthermore, only the components of the steam valve are exposed to the steam heat which is in contact with the steam chamber. The drive and sensitive electrical components can be protected against the heat or even cooled.

The steam valve can consist of several individual valves that regulate the steam flow in a cascade. Preferably, however, a valve is used with which the steam flow can be regulated linearly.

Preferably, there is a differential pressure between the two ends of the steam chamber. This causes a uniform flow of steam through the steam chamber.

Furthermore, the steam chamber and the heating channel have at least one outlet from which steam and / or condensed water can be discharged.

Another aspect of the invention is the method, with a device of the type mentioned above, which is characterized in that the steam blast chamber is arranged in the steam chamber such that at least a portion of an outer wall of the steam blast chamber provided with steam outlet openings is not enclosed by the steam chamber, wherein the outer wall is heated independently of the steam outlet openings with a heater.

In an expanded embodiment of the method, it is provided that before the moistening of the fibrous web is started, only the steam chamber and / or the heating device for heating the device are supplied with steam. As a result, the device and / or the outer wall can be quickly brought to or kept at operating temperature without the risk of condensation forming in the vaporization zone when the system starts up.

The invention will be explained in more detail with reference to drawings.

In these show:

1 a cross section of the device according to the invention

2 a longitudinal section through the device

1 shows a cross section through the device according to the invention. The device shown here is commonly called a steam blow box 1 designated. The steam box consists of a steam chamber 4 in which a steam chamber 6 is brought under. The steam chamber 6 but not completely from the steam chamber 4 enclosed, but an outer wall 15 in which the steam outlet openings 11 are at least partially not from the steam chamber 4 enclosed and thus can not be heated by the working steam.

The working steam is through the working steam connection 8th in the steam chamber 4 initiated and heated so that all internal walls of the steam chamber 6 ,

The outer wall 15 points next to the steam outlet openings 11 a heating channel 7 on, which is designed so that it is as close as possible to the steam outlet openings 11 reaches so that as far as possible the entire outer wall can be heated.

The steam chamber 6 can, as in 2 shown in several zones 13 be divided, then each zone 13 a steam valve 3 assigned.

About the working steam connection 8th gets into the steam chamber 4 Steam supplied. The supplied steam then passes through the steam valves 3 and the connection channels 5 into the steam chambers 6 and from there through the nozzle outlet openings 11 in the evaporation room 16 and thus on the fibrous web 10 ,

The steam valve 3 is on the steam chamber 4 attached, so outside the steam chamber and thus in a non-heated area. So only the valve block comes 17 with the heated steam chamber 4 in touch. The steam passes through an outlet opening in the steam chamber 4 through the valve block 17 , the connecting channel in the steam chamber 6 ,

The servomotor of the steam valve 3 is on the valve block 17 attached and thus does not come directly in contact with the heat of the steam and is also very easy to maintain and assemble.

The heating channel 7 is at a separate Heizdampfenschluss 9 connected, which is separately controllable.

In 2 a longitudinal section through the device is shown. From this representation it can be seen that the steam chamber 4 from a heating steam connection 8th is supplied and the heating channel 7 from a heating steam connection 9 Opposite the steam box 1 are connected.

For controlling the steam supply 8th . 9 there is a steam control valve in each supply line 18 installed, so that the required steam can be controllably fed to the steam chamber and the heating channel.

To the outlet of the steam not needed or the condensed water know the steam chamber 4 as well as the heating channel 7 a steam and condensate outlet 14 on.

LIST OF REFERENCE NUMBERS

1

steam blow

2

steam inlet

3

Darpfventil

4

steam chamber

5

connecting channel

6

steam blow

7

heating duct

8th

Working steam connection

9

Heizdampfanschluss

10

Fibrous web

11

Steam outlet opening

12

Dampfblaskammerzone

13

drive

14

Steam and condensate outlet

15

outer wall

16

Bedampfungsraum

17

manifold

18

Steam control valve

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 4301023 A1 [0005, 0006]
• DE 4125062 A1 [0006]
• DE 19500752 A1 [0007]

Claims (13)

Device for moistening a fibrous web ( 10 ), in particular a paper, tissue or board web, which is arranged in front of a nip forming the pair of rollers, with a steam blast chamber ( 6 ) in a steam chamber ( 4 ) with a working steam connection ( 8th ) is arranged and via at least one steam valve ( 3 ) is supplied with steam, characterized in that the steam blast chamber ( 6 ) in the steam chamber ( 4 ) is arranged such that at least a part of a steam outlet openings ( 11 ) provided outer wall ( 15 ) of the steam blast chamber ( 6 ) not from the steam chamber ( 4 ) is enclosed, wherein the outer wall ( 15 ) next to the steam outlet openings ( 11 ) with a heating device ( 7 ) is independently heated. Apparatus according to claim 1, characterized in that the heating device ( 7 ) is a heating channel which is steam-heated. Apparatus according to claim 1, characterized in that the heating device ( 7 ) is an electric heater. Apparatus according to claim 1, characterized in that the heating device ( 7 ) is a heating channel, which is heated with separately supplied steam. Apparatus according to claim 1, characterized in that the heating device ( 7 ) is a heating channel, which via a Heizdampfanschluss ( 9 ) is heated with steam, which on the opposite side of the working steam connection ( 8th ) is arranged. Apparatus according to claim 1, characterized in that the steam blast chamber ( 6 ) in several zones ( 12 ) in the transverse direction to the moving fibrous web ( 10 ) and the steam chamber ( 4 ) is continuous over the entire width. Device according to claim 1, characterized in that each zone ( 12 ) via a steam valve ( 3 ) with steam from the steam chamber ( 4 ) is available. Apparatus according to claim 1, characterized in that the steam valve ( 3 ) on the steam chamber ( 4 ) is positioned so that the steam chamber ( 4 ) via the steam valve ( 3 ) and a connection channel ( 5 ) with the steam blower chamber ( 6 ) can be connected. Apparatus according to claim 1, characterized in that the steam valve ( 3 ) is a controllable valve. Apparatus according to claim 1, characterized in that the steam valve ( 3 ) a controllable pneumatic drive ( 13 ) having. Apparatus according to claim 1, characterized in that the steam valve ( 3 ) a controllable electric drive ( 13 ). Apparatus according to claim 1, characterized in that between the two ends of the steam chamber ( 4 ) A vapor pressure difference can be generated. Apparatus according to claim 1, characterized in that the steam chamber ( 4 ) and the heating channel ( 7 ) at least one output ( 14 ), from which steam and / or condensed water can be discharged.

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