DE102011086617A1 - steam blow - Google Patents

Abstract

The invention relates to a steam blower box (I, II, III, IV) for vapor deposition of a fibrous web (1), in particular a tissue web for the purpose of dry content increase and moisture transverse profiling during their manufacture, comprising a housing (5), which at a distance (s) and with a length (C) extending in the machine direction (MD) of the fibrous web (1) to be steamed, and wherein the housing (5) encloses a steam chamber (7) which is provided with steam outlet openings (10) and thus one of the fibrous web to be steamed (1) associated vaporization section (B) forms. According to the invention, it is provided that the steam outlet openings (10) having Bedampfungsstrecke (B) of a steam chamber (7) arranged main steam chamber (8) is associated with the Bedampfungsstrecke (B) in the machine direction (MD) only about 10 to 50%, preferably 10 to 30% of the machine direction (MD) extending total length (C) of the housing (5) and is concentrated only at one point of the housing (5).

Description

The invention relates to a steam blower for steaming a fibrous web, in particular a tissue web for the purpose of dry content increase and moisture cross-profiling during their manufacture, comprising a housing which is associated with a distance and with a running in the machine direction length of the fibrous web to be coated and wherein the housing is a steam chamber encloses, which is provided with steam outlet openings and thus forms a steaming path associated with the steamed web.

Steam blow boxes as web treatment devices are used in fibrous web manufacturing machines to make a dry content increase and moisture cross profile.

Such a web treatment device in the range of calenders for smoothing the fibrous web is known from DE A1 102 55716 and in the range of a press for dewatering the fibrous web, for example, from DE-A1 103 57 288 known.

Steam blow boxes in the production of tissue webs are used very rarely, because the steam blow boxes are subject to heavy pollution because of the special nature of the substance mixture for the production of the tissue web. A major problem is that fibers are released from the fibrous web by the vapor deposition or the steam jets emitted by the steam blower box and pollute the steam blower box.

This contamination can sometimes be so severe that it must be cleaned between regular stoppages of the machine to avoid disturbances of operation by the steam box itself. If you were to swivel the steam box for cleaning purposes during operation, this would change the once set operating parameters and in turn lead to disturbances. These disturbances can be web breaks or poor moisture cross sections.

In practice, such steam blow boxes are used in which the steam outlet openings are already arranged at the beginning of the blow box and thereby the steam is applied at the beginning of the box. As a result, as already mentioned, fibers are released from the web at the very beginning of the blow box, which heavily contaminate the downstream area of the steam blow box.

There are also embodiments in which the Bedampfungsstrecke is formed over a wide range or in zones. In particular, if further steam outlet openings follow or the vapor deposition takes place over a greater distance, the existing openings can clog up or block. It comes thereby to the restriction or even to the failure of the function of the steam blow box. In addition, released fibers can be literally shot at the web by the steam jets from downstream steam vents, resulting in quality degradation of the manufactured web.

It is therefore an object of the invention to provide such a steam blower box, in which the disadvantages of the prior art no longer occur.

The object of the invention is achieved with the features of claim 1. According to the invention, it is provided that the steam outlet openings having steaming section is assigned to a arranged next to the steam chamber main steam chamber, wherein the Bedampfungsstrecke in the machine direction only about 10 to 50%, preferably 10 to 30% of the also extending in the machine direction total length of the housing and only at one Body of the housing is concentrated.

The advantage of the solution according to the invention is that the steam delivered by the steam blower box is concentrated only for a short distance in the machine direction. As a result, released fibers from the fibrous web can not cause or only slight contamination.

It is useful in this context, if the Bedampfungsstrecke has a length in the machine direction, which is about 20 to 200mm, preferably 20 to 100mm and the length of the housing about 200 to 600mm, preferably 200 to 400mm. It is very expedient that the Bedampfungsstrecke is only at the end of the housing.

In fact, the inventors have recognized that tissue has a very open structure and that it does not even require a long steaming section or long effective path of the steam, as is customary in the prior art. It is therefore possible to make the production of tissue more effective by increasing the dry content of the web with the inventive short steaming section and concentration of the steaming section at only one point of the housing of the steam blow box and undertaking a moisture cross-profiling where the tissue web is passed over a pressure roller and pressed against a creping cylinder.

A further advantageous embodiment of the steam blower box is that in End portion of the housing has the end of the Bedampfungsstrecke to the edge of the housing in the machine direction extending distance, which is about 20 to 200mm, preferably 50 to 150mm. This means that only the rear steam outlet openings are arranged at said distance.

It is advantageous if the steam outlet openings of the Bedampfungsstrecke are arranged in rows, with a plurality of rows is advantageous. Depending on the overall size of the steam blow box, one to six, preferably one to four rows may be provided. Within the rows, the individual outlet nozzles are preferably evenly spaced from one another.

The steam outlet openings of the Bedampfungsstrecke each have the same diameter. Their size is about 3 to 6mm, preferably 3.5 to 4.5mm. These nozzles are acted upon in such a way that the speed at which the steam exits the steam outlet openings is about 10 to 60 m / s, preferably 10 to 40 m / s. Thus, on the one hand, a very effective heating and moistening of the fibrous web, in particular tissue web, can be ensured.

On the other hand, a leaching of fibers from the web is avoided, but at least reduced.

So that impurities and other particles deposited less than before on the outer surface of the housing of the steam blow box, the outer surface of the housing, but at least the surface facing the fibrous web to be vaporized, a roughness of <10 microns.

In this context, it can be provided that the outer surface of the housing, but at least the surface facing the fibrous web to be coated, is polished or provided with a dirt-repellent coating, for example tetrafluoroethylene (PTFE). Even with this, cleaning intervals can be extended considerably.

An advantageous embodiment of the steam blower box is that the surface of the housing, which faces the fibrous web to be coated and extends over the inner gas chamber and the main gas chamber with the Bedampfungsstrecke, in a uniform distance of about 5 to 30mm, preferably 15 to 25mm, is arranged to be steamed fibrous web.

An alternative embodiment of the steam blow box is that the Bedampfungsstrecke or the surface of the housing of the main steam chamber, which faces the steamed fibrous web is disposed at a smaller distance from the moving fibrous web, as the surface of the remaining housing in which the inner Gas chamber is located. In this case, the Bedampfungsstrecke or the surface of the housing of the main steam chamber of the remaining surface in front of a certain distance.

A further alternative embodiment, in contrast to the previous embodiment is that the Bedampfungsstrecke or the surface of the housing of the main steam chamber is set back from the other surface at a certain distance. This means that the Bedampfungsstrecke is arranged at a greater distance from the moving fibrous web.

The choice of which of the three embodiments described above is to be incorporated into the manufacturing machine depends on the type and structure of the fibrous web.

The respective distances for the second and third embodiments are described in subclaims.

The steam blower box according to the invention is, as already mentioned, preferably usable for tissue webs. It is particularly suitable for use in the production of tissue webs with high air permeability and with a basis weight of equal to / less than 30 g / m ² .

With the steam blower box according to the invention, an increase in the dry content and a regulation of the moisture cross profile can be achieved very efficiently, without the environment and the steam blower itself being excessively contaminated by fibers liberated during the vapor deposition. The web production process can thus be carried out continuously. The quality of the produced web, in particular tissue web can be increased thereby. In addition, now no cleaning in addition to planned cleaning intervals must be carried out, which among other things, the runnability (web run property) is significantly improved.

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

In a rough schematic representation:

1 : a steam box 1 according to the invention, which is installed in a tissue-making machine, in a rough schematic representation

2 : A cross section of a steam blow box according to the invention II in a first embodiment,

3 : A cross section of a steam blow box according to the invention III in a second embodiment,

4 : A cross section of a steam blow box according to the invention IV in a third embodiment,

In the figures, the same elements are given the same reference numerals.

In the 1 is the installation of a steam blow box according to the invention I (as well as described further embodiments II . III . VI of the steam box) into a tissue-making machine. It serves to steam and heat a fibrous web 1 , In particular a tissue web of high air permeability and with a basis weight of equal to / less than 30g / m ² for the purpose of dry content increase and moisture transverse profiling during their production. The steam box I has a relatively short length C and is, as in 1 to see a pressure roller 2 assigned by the fibrous web - ie tissue web - runs in the example. The pressure roller 2 is against a creping cylinder 3 employed and forms with the crepe cylinder 3 a nip 4 The with the help of the steam box I moistened and heated track 1 in order to produce the desired creped tissue surface in the direction of travel L or in the machine direction (MD).

In the 1 is also indicated in relation to the total length C of the steam blow box I very small distance or zone in which the steaming of the fibrous web 1 takes place. This route is referred to below with Bedampfungsstrecke B. As can be clearly seen, the Bedampfungsstrecke B is only at one point of the entire housing 5 the steam box I concentrated and in the end 6 of the steam box I , Viewed in the machine direction (MD), the Bedampfungsstrecke B is only about 10 to 50%, preferably 10 up to 30% of the total length (C) of the housing 5 ,

A first embodiment of the steam blow box is shown in FIG 2 shown more clearly, the here with II should be designated.

The housing 5 encloses a steam chamber 7 with a main steam chamber 8th , at their steaming fibrous web 1 facing surface nine with steam outlet openings 10 is provided, from which the superheated steam to the fibrous web 1 is delivered. The area nine with the steam outlet openings 10 it already forms in 1 explained Bedampfungsstrecke B. The Bedampfungsstrecke B has moreover a length in the machine direction MD, which is about 20 to 200mm, preferably 20 to 100mm, whereas the length of the housing C is about 200 to 600mm, preferably 200 to 400mm.

In the end area 6 of the housing 5 is the end of the steaming stretch B to the edge 11 of the housing 5 arranged in a running in the machine direction MD distance A. This distance A is about 20 to 200mm, preferably 50 to 150mm.

One recognizes in the 2 also that the steam outlet 10 the Bedampfungsstrecke B in rows 12 are arranged. Preference is given to a row number of one to four, but also up to six rows 12 are dependent on the size of the steam blow box I or II possible.

The steam outlet openings 10 have a diameter of about 3 to 6mm, preferably 3.5 to 4.5mm. The speed with which the steam from the steam outlet openings 10 Outlet is about 10 to 60m / s, preferably 10 to 40m / s.

The outer surface of the housing 5 but at least the area nine the Bedampfungsstrecke B, the steamed fibrous web 1 facing, has a roughness of <10 microns.

The said area nine or the housing 5 is polished or provided with a dirt-repellent coating, such as tetrafluoroethylene (PTFE).

From the 2 also shows that the area nine of the housing 5 , the fibrous web to be steamed 1 is facing and over the inner gas chamber 7 and the main gas chamber 8th with the Bedampfungsstrecke (B) ranges, at a uniform distance s to steamed fibrous web 1 is arranged. the distance s is about 5 to 30mm, preferably 15 to 25mm.

In the 3 a further embodiment of the steam blow box is shown here with III should be designated. In principle, it is the same as the box I and II , but here is the Bedampfungsstrecke B or the area 9.1 of the housing 5 respectively. 5.1 the main steam chamber 8th at a smaller distance from the moving fibrous web 1 arranged as at the steam box I and II , This is the area 9.1 at a distance s1, which is about 5 to 15mm to the rest of the housing 5.2 in which is the inner gas chamber 7 located, upstream. The area 9.2 of the housing part 5.2 that of the fibrous web 1 is facing, is at a distance s3 of about 10 to 30mm, preferably 10 to 20mm to the fibrous web 1 arranged.

In the 4 a further embodiment of the steam blow box is shown here with IV should be designated. In principle, it is the same like the steam box I and II , but here is the Bedampfungsstrecke B or the area 9.1 of the housing 5 respectively. 5.1 the main steam chamber 8th at a greater distance from the moving fibrous web 1 arranged. This is the area 9.1 at a distance s2 from the rest of the surface 9.2 of the housing part 5.2 set back. Said distance s2 is about 5 to 15mm, while the area 9.2 of the housing part 5.2 at a distance s of about 5 to 30mm, preferably 15 to 25mm to the fibrous web 1 is arranged.

It should be added that the steam box I to IV each still a steam supply 13 and an actuator 14 having valve block for controlling existing steam valves.

LIST OF REFERENCE NUMBERS

1

 Fibrous web

2

 pressure roller

3

 Yankee dryer

4

 nip

5

 casing

5.1

 Housing of the main steam chamber

5.2

 Housing of the steam chamber

6

 end

7

 steam chamber

8th

 Main steam chamber

9.1

 Area of the main steam chamber

9.2

 Area of the steam chamber

10

 Steam outlet opening

11

 Edge of the case

A

 distance

B

 Bedampfungsstrecke

C

 Length of the housing

s, s1, s2, s3

 distance

L

 Web direction

MD

 Machine direction

I, II, III, IV

 steam blow

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 10255716 A1 [0003]
• DE 110357288 A1 [0003]

Claims (14)

Steam box ( I . II . III . IV ) for steaming a fibrous web ( 1 ), in particular a tissue web for the purpose of increasing the dry content and moisture transverse profiling during its production, comprising a housing ( 5 ), which at a distance (s) and with a running in the machine direction (MD) length (C) of the fibrous web to be coated ( 1 ) and wherein the housing ( 5 ) a steam chamber ( 7 ), which with steam outlet openings ( 10 ) and thus one of the fibrous web to be coated ( 1 ) associated steaming section (B), characterized in that the steam outlet openings ( 10 ) having a steaming section (B) next to the steam chamber ( 7 ) arranged main steam chamber ( 8th ), wherein the Bedampfungsstrecke (B) in the machine direction (MD) only about 10 to 50%, preferably 10 to 30% of the machine direction (MD) extending total length (C) of the housing ( 5 ) and only at one point of the housing ( 5 ) is concentrated. Steam box ( I . II . III . IV ) according to claim 1, characterized in that the steaming section (B) has a length in the machine direction (MD) which is about 20 to 200 mm, preferably 20 to 100 mm and the length (C) of the housing ( 5 ) is about 200 to 600mm, preferably 200 to 400mm. Steam box ( I . II . III . IV ) according to claim 1 and 2, characterized in that the Bedampfungsstrecke (B) at the end ( 6 ) of the housing ( 5 ) is located. Steam box ( I . II . III . IV ) according to claim 3, characterized in that in the end region ( 6 ) of the housing ( 5 ) the end of the evaporation zone (B) to the edge of the housing ( 5 ) has a machine direction (MD) extending distance (A), which is about 20 to 200mm, preferably 50 to 150mm. Steam box ( I . II . III . IV ) according to claim 1 to 4, characterized in that the steam outlet openings ( 10 ) of the steaming section (B) in rows ( 11 ), wherein a number (n) of rows ( 11 ), in particular one to six, preferably one to four rows ( 11 ) are provided. Steam box ( I . II . III . IV ) according to claim 5, characterized in that the steam outlet openings ( 10 ) of the Bedampfungsstrecke (B) have a diameter of about 3 to 6 mm, preferably 3.5 to 4.5 mm and the speed at which the steam from the steam outlet openings ( 10 ) exit is about 10 to 60m / s, preferably 10 to 40m / s. Steam box ( I . II . III . IV ) according to claim 1 to 6, characterized in that the outer surface of the housing ( 5 ), but at least the area ( 5.1 . 5.2 ), which faces the fibrous web (10) to be coated, has a roughness of <10 μm. Steam box ( I . II . III . IV ) according to claim 7, characterized in that the outer surface of the housing ( 5 ), but at least the area ( 5.1 . 5.2 ), the fibrous web to be coated ( 1 ), is polished or provided with a dirt-repellent coating, such as tetrafluoroethylene (PTFE). Steam box ( II ) according to claim 7 or 8, characterized in that the surface ( nine ) of the housing ( 5 ), the fibrous web to be coated ( 1 ) and which via the inner gas chamber ( 7 ) and the main gas chamber ( 8th ) with the Bedampfungsstrecke (B), at a uniform distance (s) of about 5 to 30mm, preferably 15 to 25mm, to be vaporized fibrous web ( 1 ) is arranged. Steam box ( III ) according to claim 7 or 8, characterized in that the Bedampfungsstrecke (B) or the surface ( 9.1 ) of the housing ( 5.1 ) of the main steam chamber ( 8th ), the fibrous web to be coated ( 1 ), at a smaller distance from the moving fibrous web ( 1 ) than the area ( 9.2 ) of the spaced (s3) remaining housing ( 5 . 5.2 ), in which the inner gas chamber ( 7 ), wherein the vaporization section (B) or the surface ( 9.1 ) of the housing ( 5.1 ) of the main steam chamber ( 8th ) of the remaining area ( 9.2 ) is arranged at a distance (s1) upstream. Steam box ( IV ) according to claim 7 or 8, characterized in that the Bedampfungsstrecke (B) or the surface ( 9.1 ) of the housing ( 5.1 ) of the main steam chamber ( 8th ), the fibrous web to be coated ( 1 ), at a greater distance from the moving fibrous web ( 1 ) than the area ( 9.2 ) of the spaced (s) remaining housing ( 5.2 ), in which the inner gas chamber ( 7 ), wherein the vaporization section (B) or the surface ( 9.1 ) of the housing ( 5.1 ) of the main steam chamber ( 8th ) opposite the remaining surface ( 5.2 ) is set back at a distance (s2). Steam box ( III ) according to claim 10, characterized in that the distance (s1) is about 5 to 15mm, whereas the distance (s3) is about 10 to 30mm, preferably 10 to 20mm. Steam box ( IV ) according to claim 11, characterized in that the distance (s2) about 5 to 15mm and the distance (s) about 5 to 30mm, preferably 15 to 25 mm to be steamed fibrous web () is. Steam box ( I . II . III . IV ) according to one of the preceding claims, characterized in that it is preferably provided for tissue webs of high air permeability and with a basis weight of equal to / less than 30 g / m ²

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