DE10327193A1 - Feed unit supplying fibrous suspension to header box of papermaking machine, includes precautions preventing built-up of contaminants and layers - Google Patents

Abstract

The unit includes one or more precautions (3) against contamination and build-up of layers on the internal wall in the tubular assembly (1). The precaution is a flow spoiler (3). It is set at a fixed sloping angle with respect to the main flow of fibrous suspension. There are a number of spoilers, alternating in direction. They are located high in the tubular assembly. Spoiler height is 1-150 mm, preferably 10-20 mm. It is a plate attached by welding. It is profiled in cross section. It is rounded, an equilateral triangle or tapered. Spoilers are spaced apart by 2-20 times their height. They have a desired, non-linear form. Air outlet openings (4) intervene between them.

Description

The The invention relates to a feeder with an inner wall having a tubular arrangement for supplying a Pulp suspension to a headbox in a machine for manufacturing a fibrous web, in particular a paper, board or tissue web.

Of the Term "feeder" is used in this context Description for all systems for direct or indirect feeding of a pulp suspension to a headbox, so for leading the pulp suspension Pipelines and return lines, for containers and like that, used. These systems can also be part of the constant Be part of the machine for producing the fibrous web.

From the German patent application DE 197 18 034 A1 a device for machine-wide distribution of a pulp suspension flow on a sieve or between two screens is known which serves in particular as the headbox of a paper or board machine. The device is equipped with a feed tube, that is to say a transverse distributor tube, which extends over the entire width of the device. Above the transverse distribution tube there are means for dividing the supplied pulp suspension flow onto a plurality of section conduits and a pulsation damper for damping the pulp suspension flow.

The supply pipes run in their end perpendicular to the direction of production the machine for the production of the fibrous web and give over the Width of the machine the pulp suspension to the headbox from. According to the prior art, they have a smooth inner wall. This leads various feeders for one Pulp suspension to ensure that in horizontal outflow in End portion of the feed tube, So in the transverse distribution pipe, and at high air contents especially in upper area dirt and deposits occur.

The in the pulp suspension distributed small bubbles only low climbing speeds. Nevertheless, you have to assume that these on the inner wall in the upper area in Transverse direction of the machine for producing the fibrous web, based to the production direction of the machine. In extreme cases, this leads to a kind of secondary flow with a high gas content in the form of a foam layer flow. This Process is still supported by the formation of the airfoil in the direction perpendicular to the machine, as in the edge zone smaller flow rates to rule.

The Foam layer leads to that no contact between the fiber leading pulp suspension and the wall is in the area of the foam layer. Therefore, the Fibers there are not the little particles that stick to the wall set down, carry away. They deposit themselves on the wall, so that the wall in the course time with them.

These operations usually found in the entire feeder, including in the pulsation damper, instead of. But are parts of the feeder ascending (including the pulsation damper), so deposits of particles are not so noticeable there. In places with higher flow rate the pulp suspension are material deposits due to turbulence not so serious. In Quererverteilrohr for the headbox ever but are the particle deposits the strongest, as this is laid horizontally and the flow rate is lower there is.

Of further results in the leading a pulp suspension feeding a consistency profile, wherein basically water in the edge zone accumulates. The consistency profile decreases in the center area of the feeder the biggest values on (homogeneous core flow) and weakens to the edge region, in particular to the upper part of the edge region, down. These inhomogeneities in the pulp suspension can to Substance density fluctuations in the headbox or to weight fluctuations lead in the fibrous web to be produced.

From the German patent application DE 198 19 330 A1 For example, a pipeline carrying a fibrous suspension is known to be in a paper machine having a main flow direction. In the pipeline means for reducing, preferably extinguishing rotational flows are provided around the main flow direction. These means consist for example of at least one flat plane of finite thickness, which runs parallel to the main flow direction. The disclosed agents act as swirl breakers, but do not prevent or inhibit deposits of particles, ie soiling and deposits, in the feeder in the form of a pipeline.

It The object of the invention is the deposition of particles in the feeding to prevent as well as the expression a consistency profile in the flowing pulp suspension to avoid. The deposition of particles includes, among other things, soiling and coverings.

According to the invention this task is at egg ner feeding device of the aforementioned type achieved in that the supply means comprises means for avoiding contamination and deposits on the inner wall in the tubular arrangement.

According to the invention are any means that cause the effect on the Walls of the feeder, especially in the critical region of the boundary layers and / or shear layers, do not form deposits. An advantage of the invention is that also the flow in the transverse distribution pipe for homogenised the headbox, especially in the edge area becomes. This carries among other things, to improve uniformity the fibrous web to be produced.

advantageous Further developments of the invention will become apparent from the dependent claims, the Description and the figures.

The simplest embodiment of the means for preventing deposits consists in Störkörpern, where this means at least one disruptive body, in particular at least one noise bar, include. By using the bluff bodies in the critical area the deposits of particles there is increased turbulence and thus reduces the tendency to fouling. This effect is on the one hand through an improved flow profile and on the other hand, by avoiding the separation of those in the Pulp suspension entrained air bubbles reached from the main stream.

A advantageous arrangement of the bluff body exists in that the at least one disruptive body is perpendicular to the main flow direction the pulp suspension is arranged.

As well let yourself provide with advantage that the at least one disruptive body under a fixed angle, in particular obliquely, to the main flow direction the pulp suspension is arranged and / or that a plurality of disruptive bodies are provided, which are arranged alternately, in particular in opposite directions.

There The air bubbles present in the fibrous suspension are after Move above, the at least one bluff body is advantageously in the upper Range of tubular Arrangement attached.

When prove suitable dimensions of the bluff body, where this one Height in Range between 1 and 150 mm, preferably in the range between 10 and 20 mm.

Advantageous the bluff bodies become at least partially as welded on Trays formed.

In another advantageous embodiment, the at least one Disruptive body in Cross section profiled.

Other advantageous geometries are that the at least one Bluff body rounded, as is formed equilateral triangle or leaking.

From It is also an advantage when the bluff body is in are mounted at a distance from each other in the arrangement, the from twice to twenty times its height.

The Formation of turbulence is enhanced if the at least one Disruptive body one has curved, not straight shape.

As well let yourself choose the arrangement of the means or the bluff body so that between them vents are arranged to air bubbles derive.

The Application also refers to the use of a feeder according to one of the preceding claims in a distributor tube, in particular a transverse distribution pipe, for a headbox.

Further Features and advantages of the invention will become apparent from the following Description of preferred embodiments with reference on the drawing.

It demonstrate:

1 : a Zuführverteilrohr in schematic cross section;

2 : the supply distribution pipe of 1 in a schematic plan view;

3 a further embodiment of a feed tube in a schematic sectional view; and

4 : the feed pipe of the 3 in schematic cross section AA.

Through a supply manifold shown in schematic cross section 1 ( 1 ) flows a pulp suspension (directional arrow) to several section lines 2 from which it enters a pre-chamber (not shown) to a turbulence generator of a headbox of a paper or board machine. The feed distribution pipe 1 has accordingly over its length by the Abflie into the section lines 2 decreasing pulp suspension stream has a longitudinally tapered conical shape ( 2 ).

In the upper part of the feed distribution pipe 1 are sturgeons 3 arranged, which are designed for example in the form of strips. The disruptive bodies 3 extend at an acute angle with respect to the longitudinal axis of the Zuführverteilrohrs and the main flow direction.

The disruptive bodies 3 have a height in the range between 1 and 150 mm, preferably in the range between 10 and 20 mm. They are formed for example by simple, perpendicular welded sheets. However, these can also be profiled in cross-section, in particular rounded, or designed as equilateral triangles or discontinued. Their distance between them is two to twenty times their height. They can also have a curved, not straight shape.

Between the disturbing bodies 3 , For example, in the flow direction of the pulp suspension (directional arrow) immediately behind them, are vent holes 4 attached, over which the air bubbles, which adhere to the Störkörpern 3 accumulate, escape to the top.

Furthermore flows through a feed pipe shown in schematic cross section 5 , in particular pipeline, ( 3 ) a pulp suspension (directional arrow) to said headbox of a paper or board machine. The feed tube 5 has a cylindrical or approximately cylindrical shape.

In the upper part of the feed pipe 5 are also disruptive bodies 3 arranged, for example, in the form of the bluff body 3 of the 1 and 2 exhibit; These two figures are hereby incorporated by reference. The disruptive bodies 3 have a curved, not straight shape and are alternately arranged, in particular in opposite directions, so that no swirl in the flow direction of the pulp suspension (directional arrow) is generated. The arrangement of the bluff bodies is preferably in groups on the circumference of the inner wall ( 4 ).

Between the disturbing bodies 3 , For example, in the flow direction of the pulp suspension (directional arrow) immediately behind them, are, as already mentioned above, vent holes 4 attached, over which the air bubbles, which adhere to the Störkörpern 3 accumulate, escape to the top.

1

Zuführverteilrohr

2

section leader

3

disturbing body

4

vent hole

5

feed

A-A

intersection

Claims (14)

Feeding device with an inner wall having a tubular arrangement ( 1 ) for supplying a pulp suspension to a headbox in a machine for producing a fibrous web, in particular a paper, board or tissue web, characterized in that the feed means ( 3 ) for avoiding soiling and deposits on the inner wall in the tubular arrangement ( 1 ) having. Feeding device according to claim 1, characterized in that the means comprise at least one disruptive body ( 3 ), in particular at least one noise bar ( 3 ). Feeding device according to claim 2, characterized in that the at least one disruptive body ( 3 ) is arranged perpendicular to the main flow direction of the pulp suspension. Feeding device according to claim 2, characterized in that the at least one disruptive body ( 3 ) is arranged at a fixed angle, in particular obliquely, to the main flow direction of the pulp suspension. Feeding device according to one of claims 2 to 4, characterized in that a plurality of disruptive bodies ( 3 ) are provided, which are arranged alternately, in particular in opposite directions. Feeding device according to one of claims 2 to 5, characterized in that the at least one disruptive body ( 3 ) is mounted in the upper region of the tubular arrangement. Feeding device according to one of claims 2 to 6, characterized in that the at least one disruptive body ( 3 ) has a height in the range between 1 and 150 mm, preferably in the range between 10 and 20 mm. Feeding device according to one of claims 2 to 7, characterized in that the at least one disruptive body ( 3 ) comprises a welded sheet metal. Feeding device according to one of claims 2 to 8, characterized in that the mindes at least one disruptive body ( 3 ) is profiled in cross section. Feeding device according to claim 9, characterized in that the at least one disruptive body ( 3 ) Rounded, is formed as an equilateral triangle or leaking. Feeding device according to one of claims 2 to 10, characterized in that the disruptive bodies ( 3 ) are arranged at a distance from each other in the arrangement which is twice to twenty times their height. Feeding device according to one of claims 2 to 11, characterized in that the at least one disruptive body ( 3 ) has a curved, not straight shape. Feeding device according to one of the preceding claims, characterized in that between the means ( 3 ) Vents ( 4 ) are arranged. Use of a feed device according to one of the preceding claims in a distributor tube ( 2 ), in particular transverse distribution pipe, for a headbox.