WO2016026631A1

WO2016026631A1 - Steam blower box

Info

Publication number: WO2016026631A1
Application number: PCT/EP2015/066413
Authority: WO
Inventors: Frank Wegehaupt
Original assignee: Voith Patent Gmbh
Priority date: 2014-08-19
Filing date: 2015-07-17
Publication date: 2016-02-25

Abstract

The invention relates to a steam blower box for applying a paper, paperboard, tissue or other fibrous material web (1) in a machine for the production and/or refinement thereof with steam, wherein at least one steam-filled pressure chamber (2) of the steam blower box is connected to one or more nozzles directed at the fibrous material web (1). For this purpose, in order to achieve a simple zonal control of the steaming, the outlet openings (3) of the nozzles of the pressure chamber (2) form an outlet surface (6) of the pressure chamber (1), and at least one section of the outlet surface (6) is assigned a controllable cover (5) for changing the effective nozzle cross-sectional area in this section.

Description

steam blow

The invention relates to a steam blower box for applying a paper, cardboard, tissue or other fibrous web in a machine for producing and / or finishing the same with steam, wherein at least one steam-filled pressure chamber of the steam blower box with one or more directed to the fibrous web nozzles communicates. Such steam blow boxes are used in particular in the press section or in smoothing arrangements of paper machines.

By acting on the fibrous web with the hot steam, the web temperature is increased and the viscosity of the water in this lowered.

This is often done in several separately controllable zones across the web running direction. For this purpose, the steam blower box has several transverse to the web running direction juxtaposed chambers with a width between 40 and 400 mm, which are each connected via a control valve with a common steam supply chamber.

Each of these chambers has its own nozzles that direct the steam to the fibrous web. Because of the different vapor pressures in the chambers, the exit velocity of the vapor also differs, which can affect the efficiency of the steam blow box.

A separate steam supply of the chambers would increase the cost significantly.

The object of the invention is therefore to improve the efficiency of the steaming with the least possible effort. According to the invention, this object is achieved in that the outlet openings of the nozzles of the pressure chamber form an exit surface of the pressure chamber and at least a portion of the exit surface is assigned a controllable cover for changing the effective, ie traversed by the steam nozzle cross-sectional area in this section.

In this way, the amount of steam that flows from the respective section of the exit surface onto the fibrous web can be easily changed and thus adapted to the requirements of the fibrous web or the process,

If a larger amount of steam to act on the fibrous web, the cover releases a larger nozzle cross-sectional area and vice versa.

This eliminates the need for chambers, which significantly reduces the effort.

The exit velocity at which hot steam exits the nozzles thus depends on the pressure in the pressure chamber and the open, i.e., the pressure of the water. the released from the covers nozzle cross-sectional area of the nozzles. Accordingly, the exit velocity is the same for all nozzles of an exit surface.

This in turn allows accurate metering of the amount of steam which is to act on the fibrous web over the individual sections of an exit surface. As a result, this saves energy.

Depending on the nature and extent of the amount of steam to be applied and different nozzle shapes can be used.

The application of much steam with a compact jet is possible if the pressure chamber communicates with only one, preferably slot-shaped nozzle. Here, the slot should extend transversely to the direction of web travel. About the covers while the slot width can be varied in the respective sections. If, for example, a smaller amount of steam is to be sprayed onto the fibrous web and / or the exit surface of the steam blower box is widened in the web running direction, then it may be advantageous if the pressure chamber communicates with a plurality of nozzles.

If the cross-sectional areas of the nozzles of the pressure chamber have the same shape and preferably also the same size, this can simplify the production of the exit surface.

In contrast, over different cross-sectional areas of the nozzles of the pressure chamber, an adaptation to the specific requirements in the respective sections possible.

Depending on the shape and circumference of the nozzle openings, it may be advantageous if the corresponding cover is formed by a closed surface or at least has a passage opening.

In both cases, a partial or complete closing of the nozzle openings is possible.

In order to enable control of the amount of steam in as many zones transverse to the direction of web travel, a plurality of, adjacent to the web running direction or spaced apart sections of the exit surface of the pressure chamber should each be assigned a controllable cover.

For ease of construction, the cover should be located in front of the inlet side of the nozzles. Thus, a pollution is vorgebeut.

In order to change the pressure in the pressure chamber and thus also the exit velocity of the steam from the nozzles, the amount of steam supplied to the pressure chamber should be adjustable via a control valve. If the exit velocity is too small, the vapor can not or not completely penetrate the air boundary layer of the high-speed fibrous web. At least part of the steam is then entrained and lost. Too high an exit velocity can cause a reflection of the vapor on the fibrous web surface before it can condense there. Damage to the fiber structure is also possible.

Therefore, it is advantageous if the pressure in the pressure chamber is controlled via the control valve such that, depending on the open nozzle cross-sectional area of the exit surface of the pressure chamber, the exit velocity of the vapor remains within a predetermined range and preferably constant.

In particular, in narrow machines, it can often already be sufficient if the steam blower box has only one pressure chamber.

For better adaptation to the conditions of the machine, however, it may also be advantageous if the steam blower box has a plurality of pressure chambers, one or more of which have at least one cover.

This makes it possible, for example, to build up different pressures in the pressure chambers, which also allows different exit speeds.

The invention will be explained in more detail below with reference to several exemplary embodiments.

In the attached drawing shows:

Figure 1: a cross section through a steam blower box;

Figure 2: a section of the exit surface 6 of Figure 1 and

Figure 3: a cross section through another steam box and

Figure 4: a section of the exit surface 6 of Figure 3 and

Figure 5: a steam box with multiple pressure chambers 2 and

Figure 6: an exit surface 6 with only one nozzle. The steam blow boxes shown here serve to act on a passing fibrous web 1, in particular a paper web with hot water vapor.

The vapor condenses on the surface of the fibrous web 1 and thus increases its temperature and humidity. In order to be able to influence the cross profile of fibrous web properties, such as the moisture transverse profile, in a targeted and efficient manner, the intensity of the vapor application in zones or sections transversely to the web running direction 8 can be controlled separately.

The steam blow box illustrated in FIGS. 1 to 4 is essentially formed by only one pressure chamber 2, in which steam is at a pressure between 0.1 and 1.5 bar pressure. In the directed to the fibrous web 1 side wall of the pressure chamber 2 are a plurality of evenly distributed over an exit surface 6 arranged nozzles. From the outlet openings 3 of these nozzles, the steam flows at a speed between 10 and 150 m / s, preferably between 30 and 80 m / s. In this way, it is ensured that the steam jet can overcome the air boundary layer entrained by the fibrous web 1.

In a particularly cost-effective embodiment, the exit surface 6 is formed in Figure 1 and 2 of a metal sheet of the side wall of the steam blower box, so that the nozzles with their outlet openings 3 can be easily created through through holes in this metal sheet.

In order to be able to independently control the amount of steam reaching the fibrous web 1 in a plurality of sections lying transversely to the web running direction 8, a controllable cover 5 is assigned to each of these sections. To protect against contamination and in the interest of a simple structure, the covers are 5 in front of the inlet openings of the nozzle, ie in front of the pressure chamber 2 facing side wall of the steam box.

The shifting of the covers 5 takes place in all embodiments via electrical, hydraulic or pneumatic actuators 4 in the web running direction 8.

By means of the partial or complete covering of nozzles of the respective section, the open cross-sectional area through which the vapor can flow can thus be changed.

In Figures 1 and 2, the covers 5 are formed by a closed surface.

In contrast to this, the exit face 6 in FIG. 6 has only one slot-shaped nozzle whose slot-shaped outlet opening 3 extends transversely to the web running direction 8 at least approximately over the entire pressure chamber 2. Again, the slot width and thus the amount of steam of the respective portion of the exit surface 6 can be changed by moving the transverse to the web running direction 8 juxtaposed covers 5. In the embodiment according to FIGS. 3 and 4, the covers 5 have

Passage openings 7, which coincide with the inlet openings of the nozzles. If the passage openings 7 are aligned over the inlet openings of the nozzles, then a maximum amount of steam flows through the nozzles. Moving the

Covers 5 reduces the open area of the inlet openings of the nozzles and thus also the amount of steam passing through the nozzles in the relevant section.

In this case, the exit surface 6 of the steam blow box comprises two parallel, spaced-apart and transverse to the web running direction 8 strips. The nozzles are located transversely to the web running direction 8 alternately in different strips and are parallel in each section of the exit surface 6 of four, spaced apart and formed transversely to the web running direction 8 slots.

Accordingly, each cover 5 has four parallel, spaced-apart and transversely to the web running direction 8 extending, slot-shaped passage openings. 7

Since the nozzles of each section communicate with the same pressure space 2, the exit velocity of the steam from the nozzles is also the same across these sections. In order to be able to adapt the exit speed to the requirements, therefore, as can be seen in FIG. 5, the quantity of steam supplied to the pressure chamber 2 should be adjustable via a control valve 9.

Via the control valve 9, the pressure in the pressure chamber 2 can be controlled such that, depending on the open nozzle cross-sectional area of the exit surface 6 of the pressure chamber 2, the exit velocity of the vapor remains constant within a predetermined range and preferably constant.

The steam blower box in Figure 5 has next to the pressure chamber 2 with the covers 5 in each case in the edge region of the fibrous web 1 still another, narrow pressure chamber 2 without cover 5. Also in the pressure chambers 2 without cover 5, the steam supply is controlled by control valves 9.

In the edge region of the fibrous web 1, other requirements for the profiling are often given, which is why a larger or smaller pressure may be required here in comparison to the average pressure chamber 2.

Claims

Claims 1. Steam blower box for applying a paper, board, tissue or other fibrous web (1) in a machine for producing and / or finishing it with steam, wherein at least one steam-filled pressure chamber (2) of the steam blower box with one or more to the fibrous web (1) directed nozzles, characterized in that the outlet openings (3) of the nozzles of the pressure chamber (2) form an outlet surface (6) of the pressure chamber (2) and at least a portion of the exit surface (6) a controllable cover (5 ) is assigned to change the effective nozzle cross-sectional area in this section.

2. steam blower box according to claim 1, characterized in that the

Pressure chamber (2) communicates with only one nozzle, which is preferably formed slit-shaped.

3. steam blower box according to claim 1, characterized in that the pressure chamber (2) is in communication with a plurality of nozzles.

4. steam blower box according to claim 3, characterized in that the

Cross-sectional areas of the nozzles of the pressure chamber (2) have the same shape.

5. steam blower box according to claim 3, characterized in that the

Cross-sectional areas of the nozzles of the pressure chamber (2) have different shapes.

6. steam blower box according to one of the preceding claims, characterized in that the cover (5) is formed by a closed surface.

7. steam blower box according to one of claims 1 to 5, characterized in that the cover (5) has at least one passage opening (7).

8. Steam blower box according to one of the preceding claims, characterized in that a plurality of transversely to the web running direction (8) adjacent or spaced apart portions of the exit surface (6) of the pressure chamber (2) is associated with a controllable cover (5).

9. steam blower box according to one of the preceding claims, characterized in that the cover (5) is located in front of the inlet side of the nozzle.

10. steam blower box according to one of the preceding claims, characterized in that the pressure chamber (2) supplied amount of steam via a control valve (9) is adjustable.

1 1 .Dampfblaskasten according to claim 10, characterized in that the pressure in the pressure chamber (2) via the control valve (9) is controlled such that depending on the open nozzle cross-sectional area of the exit surface (6) of the pressure chamber (2) the exit velocity of Steam in a defined range and preferably remains constant.

12. steam blower box according to one of the preceding claims, characterized in that it has only one pressure chamber (2).

13. steam blower box according to one of claims 1 to 1 1, characterized in that it has a plurality of pressure chambers (2), one or more of which have at least one cover (5).