EP0633417B1 - Device and procedure for throtteling the flow of pulp slurry in a paper machine - Google Patents

Abstract

A throttle device for stock suspensions in a paper machine including a feed line, a drain line and a spatially variable cavity connecting the feed line and drain line with each other. The cavities provided with a plurality of nestable walls in which the nesting effects a lengthening of the flow path.

Description

The invention relates to a throttle device according to the preamble of independent claims 1, 2 and 8.

The invention further relates to a method for the variable throttling of a stock suspension flow.

For throttling fluid flows in a paper machine or a system for Stock preparation are valves in various designs State of the art. Significant disadvantages of these standard valves, e.g. Ball valves, needle valves, flap valves, slide valves and the like, that they are very tight to produce the desired flow resistance Need to create cross sections that tend to clog, when the fluid passing through them is mixed with fibers. This A problem also arises when a throttle channel is used according to SU-A-781478. This discloses a fine control device for small Currents for use in valve construction. In this version, the Throttle channel from a channel machined into a base plate and one Coil spring formed. The throttle channel opens into a cavity and that Operating equipment is forwarded from this into a discharge line. Of the Outlet cross section in the cavity is determined by the size of the cross section in the area of the transition from the overlap to the release of the channel certainly. There is a concrete connection between the reducing cross section of the channel, the length of the flow path from Inlet up to the outlet in the cavity and the outlet cross section in the Cavity, because to achieve the most infinitely variable adjustability of the Volume flow at the outlet as many different cross sections as possible are to be provided. This becomes continuous over a channel reducing cross-section realized, the slope chosen very flat is.

In DE-A-42 39 643 is shown a throttle device for throttling a fluid flow essentially occurring or generated therefor Turbulence phenomena uses and thus dispense with narrow cross sections can. The disadvantage of this device is its small effective range.

Starting from the throttle device according to DE-A-4239643, the object of the invention is to describe a throttle body, which is particularly suitable for use in paper machines and on the one hand, less susceptible to constipation than that Standard valves is and secondly a larger area of action than that Throttle device shown in the above application.

This object is achieved by the characterizing features of independent device claims 1, 2 and 8 as well as by the process claims 9 solved.

Appropriate developments of the invention are described in the dependent claims.

The well-known and standard way to variable resistance generation in a throttle device consists in the Change a cross-section, the impact losses generated there Determine the amount of resistance. This leads to undefined vertebrae can arise and this can lead to constipation, or that when using such throttling devices for Stock suspensions in a paper machine to so-called There is fiber wiping that has a negative impact on paper quality can.

The inventors have recognized that a possible further way of generating resistance, in particular then if the range of resistance generated is limited, is a change in the flow path. This can be done e.g. by an extension of the flow path, for example by the Stock suspension via a zigzag path within the throttle device variable amplitude is performed or by one in the basic state an approximately linear course of a flow a rotational component is added so that the more or less strong rotation with a correspondingly longer path to be traversed for the flow. Another way of throttling a flow is that the Flow energy due to different vortices is withdrawn or by connecting acceleration and Delay sections are installed in the throttle device. Naturally there is also the possibility to combine the effects described above combine, which for example also works cheap Cleaning effects can be used.

Figur 1-3:

Querschnitte durch drei Varianten der erfindungsgemäßen Drosselvorrichtung.

The invention is described in more detail with reference to the figures. It also shows the following:

Figure 1-3:

Cross sections through three variants of the throttle device according to the invention.

Figure 1 shows schematically a throttle device in which two surfaces, the course of which is wavy is moved towards or away from each other can. That is, that between the two surfaces fluid flowing through it becomes smaller the distance of the surfaces on an ever longer path forced, which is accompanied by an increase in resistance. What is important here is that the resistance that is involved is generated, not due to shock effects from extreme Bottlenecks is generated, but only because of the longer path of the liquid is generated. According to the invention there is such a device also the possibility of the two opposite To move surfaces lengthways so that additionally when flowing through the gaps acceleration and Delay effects occur because areas are larger and larger to go through smaller cross sections of the flow are.

Figure 2 shows a further invention Throttling device. Here, the liquid gets through an approximately cylindrical cavity, the inner wall with spiral waves is provided. Axial in a piston is pushed into this cavity, which also uniform waves on its outside having. The piston is completely out of the narrow range pulled out, so the liquid can be almost unhindered flow through the throttle device, the direct takes a straight path. The piston is in the constriction inserted, so the liquid is forced to one to take a spiral course, the flow with increasingly pushing the piston in longer and longer will have to cover the same route and accordingly the Resistance to the liquid grows. It is also important here that the resistance generated is not due to extreme constrictions is created, but only because of the longer distance traveled and with it naturally increased resistance also arises.

Figure 3 shows an embodiment of a throttle device Similar to Figure 2, but here they are with each other corresponding surfaces conical in their basic form executed.

Claims (10)

1. Throttling device for pulp slurries, with the following features:

   1.1 a feed pipe is provided;

   1.2 a discharge pipe is provided;

   1.3 a spatially changeable hollow space is provided which interconnects the feed pipe and the discharge pipe;

   characterised by the following feature:
   1.4 the hollow space is provided with a plurality of walls which are displaceable into each other and which cause a lengthening of the flow path when pushed into each other.
2. Throttling device for pulp slurries, with the following features:

   2.1 a feed pipe is provided;

   2.2 a discharge pipe is provided;

   2.3 a spatially changeable hollow space is provided which interconnects the feed pipe and the discharge pipe;

   characterised in that
   2.4 the hollow space is provided with helical recesses and elevations which extend around the main flow direction.
3. Throttling device according to Claim 2, characterised in that the amplitude of the recesses and elevations is provided so as to be adjustable.
4. Throttling device according to Claim 2, characterised in that a displacement element is centrally provided in the hollow space.
5. Throttling device according to Claim 4, characterised in that the expansion of the displacement element is changeable.
6. Throttling device according to Claim 4, characterised by the following features:

   6.1 the inner surface of the hollow body is essentially conical;

   6.2 the surface of the displacement element is essentially conical - axis-parallel to the hollow space -.

   6.3 the displacement element is provided so as to be displaceable along its conical axis.
7. Throttling device according to one of Claims 4 to 6, characterised in that the surface of the displacement element comprises helical elevations and recesses around the cone axis.
8. Throttling device for pulp slurries, with the following features:

   8.1 a feed pipe is provided;

   8.2 a discharge pipe is provided;

   8.3 a rotation-symmetrical hollow space is provided which interconnects the feed pipe and the discharge pipe;

   characterised in that
   8.4 the spatial angle between feed pipe and symmetry axis of the hollow element is provided so as to be adjustable.
9. Process for variable throttling of a pulp slurry, characterised in that the length of the flow path within the throttling device is continuously or discretely changed.
10. Process according to Claim 9, characterised in that a rotation flow of changeable angle of inclination is used.

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