DE202018006038U1 - Device for degassing a liquid to pasty medium, in particular a coating color - Google Patents

Abstract

Apparatus for degassing a liquid to pasty medium, in particular a coating color for coating paper or cardboard with a vacuum container (1) having an inlet (10) for the medium to be degassed and a vacuum connection (11) or vacuum generator and an outlet (12 ) for the medium to be degassed. and inside the vacuum container (1) there is further provided a rotary member (2) rotatable about an axis (21) adapted to accelerate the medium towards the container wall (1a) of the vacuum container (1), characterized in that in the interior of the vacuum container (1) there is furthermore provided an insert (3) which is arranged between the rotary element (2) and the container wall (1a) so that the medium accelerated during operation of the device bumps completely or partially against the insert (3) ,

Description

The invention relates to a device for degassing a liquid to pasty medium, in particular a coating color for coating paper or cardboard, according to the preamble of claim 1.

Such a device is known from DE-A-28 32 071 known. The device comprises a vacuum container which has an inlet for the medium to be degassed, as well as a vacuum connection or vacuum generator and an outlet for the degassed medium.
The medium is, in particular, a coating color with which, above all, a paper, board or other fibrous web is to be painted. The coating color generally consists of aqueous pigment dispersion. This is applied as uniformly as possible with a certain film thickness and dried. Such a job, also referred to as a bar, improves the printability and the optical properties of the web or performs special functions, such as barrier properties.
During the treatment process of the medium, thus, for example, the coating color, air enters the liquid or pasty medium. This forms bubbles that burst after the strike of the web and leave vacancies. The stroke is thus no longer uniform. Microbubbles with a diameter of a few micrometers, especially with thin films, are already disturbing. In order to produce an optimum line with a closed line area and great uniformity, it is therefore essential to degas or bleed the coating color. Numerous methods have become known for this purpose. One important process is vacuum degassing or vacuum venting.
The DE 199 39 275 A1 , but also the DE 10 2005 017 952 A1 describe such a method, wherein in the latter document the coating to be degassed coating is brought to a temperature in the vicinity of its boiling point, in particular to about 40 to 60 'C, and to a pressure of about 20 to 100 mbar. As a result, a volume flow of gas bubbles is generated counter to the conveying direction of the coating color. The increased vapor pressure in the vacuum degasser creates a gas flow. This ensures that small trapped gas bubbles are entrained and transported to the interface between coating color and air, where they are removed by negative pressure.
Other methods are based essentially on a mechanical effect and use the known principle of a hydrocyclone. Please refer EP 1 078 670 A1 . WO 03/00 2227 A1 . EP 0 735 913B1 . DE 40 09 042 C2 ,
The requirements for the degassing of media of the type mentioned have continued to increase. This is because the media to be degassed now have properties that make degassing more difficult. These include, for example, higher solids contents and higher viscosities. Also, the quality requirements for the coating quality have increased or the type of coating requires a particularly largely degassed medium (eg the curtain coating).
In particular for such applications is in the EP 1 798 333 proposed a vacuum fan, in which the medium to be degassed flows through the vacuum vessel from top to bottom and thereby repeatedly and alternately subjected to a high acceleration and then subjected to a slowdown by impacting the container wall. Each time a new surface is created, which can be outgassed better than before. Although the degassing performance can be improved with such a device. However, the impact of the coating on the container wall leads to contamination of the vacuum container and the fixtures attached thereto. In addition, maintenance of the breather is difficult because the individual components are difficult to remove and clean.

The object of the present invention is therefore to provide a ventilation device and a method for venting, which ensure a high ventilation performance, and wherein the device is easy to maintain, especially to clean.
It is another object of the invention to propose an efficient method for the maintenance of a ventilation device.

The object is completely solved with respect to the device by a device according to claim 1, with regard to the venting process. Further advantageous embodiments of the invention are described in the subclaims.

The device is a device for degassing a liquid to pasty medium, in particular a coating color for coating paper or cardboard with a vacuum container having an inlet for the medium to be degassed and a vacuum or vacuum generator and an outlet for the medium to be degassed and wherein there is further provided inside the vacuum container an axis rotatable rotation member adapted to accelerate the medium towards the container wall of the vacuum container. According to the invention, provision is further made for an insert to be provided in the interior of the vacuum container, which insert is arranged between the rotation element and the container wall such that the medium accelerated during operation of the device bumps completely or partially against the insert.

A vacuum container suitable for the device according to the invention usually comprises a lateral container wall and a container bottom. At the top, the vacuum container is closed by a container top. Since in conventional embodiments, the vacuum container can be opened by removing the upper container part, the term container lid is used for the upper container part in the context of the application.

An advantage of the invention consists in the fact that the medium is not thrown against the container wall, but bounces on the appropriately positioned use. This causes, inter alia, that further parts of the vacuum vessel do not come into direct contact with the medium, and therefore do not pollute. Instead, only the use is polluted. This insert can usually be cleaned easier than the vacuum tank.
In addition, many coating colors contain mineral pigments such as CaCO ₃ or TiO ₂ . These have an abrasive effect when they hit a wall at a certain speed. Such abrasion is particularly critical for pressure vessels such as a vacuum tank, as they are subject to strict safety requirements. By use in the device described here such abrasion of the container wall is avoided, since now only the use of this abrasion is exposed. Replacing a damaged insert, however, is realized with much less effort than the replacement of the entire vacuum container.

In an advantageous embodiment of the invention can be provided that the insert is open down to allow flow of the medium to the container bottom of the vacuum vessel. The vacuum container can then serve as a reservoir for degassed medium. About the outlet then the degassed medium can be easily removed. The outlet is expediently provided in the container bottom or in the lower region of the container wall.

Preferably, the insert will be carried out largely static. That is, it rotates in the operation of the vacuum fan either not at all, or only with very low rotational speed compared to the rotational speed of the rotary member. Thus, for example, the medium can be conducted away from the wall of the insert, without appreciable centrifugal forces being overcome by a rotating insert.

In further advantageous embodiments, it can be provided that the rotation element comprises at least one, in particular a plurality of turntables.
The turntable or the turntables are advantageously arranged so that they are rotatable about the axis of the rotary member. For this purpose, a shaft may be provided, to which the one or more turntables are attached. A medium, which is located on the turntable is accelerated by the rotation to the outside, in the direction of the container wall. By striking the appropriately arranged insert, the medium is braked again.

When using turntables can advantageously be provided that one or all turntables are provided on its outer circumference with a cylindrical screen surface. The medium is pressed during operation of the deaerator due to the centrifugal force from the turntable through this sieve and thereby further degassed, before it is thrown up to the use, where it is further degassed.

Furthermore, it can be provided that the insert has internals for conducting the medium. This is particularly advantageous because the medium is thrown at the operation of the breather, and from there usually flows down under the influence of gravity. In order to allow a targeted conduction of the medium therefore installations, for example in the form of baffles, advantageous.

In a very advantageous embodiment it can be provided that the rotation element comprises at least a first and a second turntable, wherein the first turntable is disposed above the second turntable, and the insert has internals for guiding the medium, which are arranged to medium, that from the first turntable has been thrown against the insert to guide on the second turntable. In this way, the medium can pass through several degassing stages so-called Kaskadenstufen- succession, which leads to an increase in the degassing quality. Analogous to the two cascade stages described here, even more cascade stages are conceivable. In practical applications, significantly more stages, for example, five cascade stages or eight cascade stages are often required to ensure adequate degassing for the application. Advantageously, the insert should be sized so that at all cascade stages, i. on all turntables, the spun medium should hit the insert, not the wall of the vacuum tank.

Furthermore, it can advantageously be provided that the insert has one or more suction openings through which pressure equalization can take place between the interior of the insert and the remaining vacuum container.
In operation, a negative pressure will usually prevail in the vacuum container. For this example, on be connected to the vacuum connection a suitable suction. So that this vacuum can also have a supporting effect on the degassing, and that the gas removed from the medium can also be discharged sufficiently quickly, it is advantageous if rapid pressure equalization in the vacuum container, in particular between the interior of the insert and the space surrounding it, can take place , It is helpful if appropriate openings are provided during use. The placement of the openings may be suitably chosen so that no medium can penetrate through them and contaminate the vacuum container.

In a further preferred embodiment it can be provided that the insert and / or the rotatable rotation element is or are attached to a container lid of the vacuum container. This is particularly advantageous if the container lid can be removed to open the vacuum container. In this case, the internals, so the insert and the rotatable rotation element can be removed very easily together with the container lid. So both these internals can be easily cleaned outside the pressure vessel and otherwise maintained. In addition, the vacuum container is now easily accessible without these fixtures and can be cleaned or serviced if necessary.

The advantages of the invention are particularly great when means are provided for easy installation and removal of the insert. These can be guide rails, for example.

Furthermore, it may be advantageous if a gap is provided between the insert and the container wall. On the one hand, such a gap can help to remove the insert from the vacuum container more easily. In an above-described lifting out of the insert, if necessary, together with the container lid and rotating element prevents such a distance tilting of the insert. In addition, a distance between the container wall and insert also promotes a uniform pressure distribution in the interior of the vacuum vessel.

In further advantageous embodiments, the insert may consist of a plastic, in particular a fiber-reinforced plastic, a metal or a combination of these materials. Particularly advantageous, for example, be a design in which the insert consists essentially of (possibly fiber-reinforced) plastic, wherein the regions of the insert, which impinges on the medium during operation, is reinforced by means of metal baffle plates. By such a local wear protection in combination with a lightweight plastic component an easy removal and installation of the insert is possible, while high wear resistance.

Furthermore, it may be advantageous if the insert consists of several parts which are detachably connected to each other. This greatly facilitates the maintenance of the device.

In preferred embodiments, the insert may have a cylindrical shape, at least for the most part. Inside the cylinder is often a rotating element, for example in the form of a number of turntables. The insert can be closed at the top. Through this top cover a shaft will often be guided, at which e.g. the turntables can be attached. At the bottom, the cylinder may have an opening. Often, the use will have no floor at all. In such an embodiment, during operation, the medium hits the inside of the lateral cylinder wall. From there, the medium can be removed via suitable internals such as e.g. Guiding plates are guided and directed, for example, to another turntable.

For maintenance, the combination of insert and rotary element can often be removed from the vacuum container. For efficient maintenance, especially cleaning, it is advantageous if all items are easily accessible for the maintenance personnel. For this purpose, it is again advantageous if the rotation element and the insert easily separated from each other, and individually maintained, in particular can be cleaned.

For such an application - but not only - it is very advantageous if the use of several parts is constructed, which can be easily solved and removed. For example, an insert in the form of a circular cylinder may advantageously be divided into segments, e.g. be decomposed into four equal segments, which may be joined together in particular by means of quick-release fasteners.

In a further advantageous embodiment it can be provided that in the device means for at least partial cooling and / or insulation are provided in or on the vacuum container. By suitable cooling and / or isolation of the vacuum container or of the medium contained therein, boiling or foaming of the medium can be prevented. This contributes both to an increased degassing performance, but also reduces pollution, e.g. by spraying the coating color inside the vacuum container.

As described above, the vacuum container can also be used as a reservoir or for a short time Buffer for degassed medium serve. Frequently, a preferred fill level ("100% level") is provided, in which the degasser is preferably operated.

With regard to cooling / isolation, this can be advantageously exploited by allowing only a certain range around this 100% level, e.g. ± 10cm, ± 20cm or ± 30cm cooling and / or insulation around this 100% level. In most cases, the surface of the medium will be in this area. Since foaming can occur only in the area of this surface, it is also possible to provide cooling and / or insulation only in this area.

Regardless of the aspect of the cooling, it may be advantageous if the use in operation extends from the top to the reservoir of degassed medium. While it is advantageous in the rotary member when mounted above the 100% level, in use e.g. the sidewall should be extended to below the 100% level. Advantageously, the insert can dip into the medium between 1 cm and 30 cm, preferably between 2 cm and 5 cm or protrude below the 100% level. This long design prevents the free dripping of the coating color and the impact of the drops on the surface of the supply of degassed medium. Such a drop may result in undesirable spatter and the associated contamination of the vacuum container. So far, it has been assumed that the free fall of the drops of the medium and the free color surface constitute an important part of the deaeration capacity. Applicants' experiments have shown, however, that prolonging the use and thereby preventing dripping does not appreciably affect the venting capacity, and that the advantage of less pollution far compensates for any possible minimal deterioration of the venting.

• • Die Verlängerung kann dabei starr sein, oder aus einem flexiblen Material - ähnlich einem Vorhang- ausgestaltet sein.
• • Die Verlängerung -insbesondere eine flexible Verlängerung- kann mit einem Schwimmkörper ausgestattet sein, so dass die Eintauchtiefe dem aktuellen Flüssigkeitsstand des Mediums angepasst werden kann.

In order to continue to ensure easy removal of the insert, it may be advantageous to be able to remove the extension of the insert into the coating color in whole or in part.
In an application that can be broken down into several parts, in particular segments, it is naturally advantageous if each of these segments receives its own, removable extension.
An extension as described above can be realized in the simple case by a plate which is adapted to the shape of the insert or a segment. This plate can be releasably secured by means of suitable suspensions on the outside or inside of the insert.

• • The extension may be rigid, or be made of a flexible material - similar to a curtain.
• • The extension - especially a flexible extension - can be equipped with a floating body, so that the immersion depth can be adapted to the current fluid level of the medium.

In a further advantageous variant it can be provided that the insert or the extension extends to the container bottom of the vacuum container. This variant is particularly advantageous if the vacuum container is operated without a reservoir or only with a very low level of degassed medium. In this case, at the lower end of the insert or the extension of a flexible part may be attached, which allows a kind of flexible seal to the bottom of the vacuum vessel.

In a further embodiment it can be provided that the insert or the extension, in particular in the part which lies below the liquid level, be designed as a filter element, which is permeable to the degassed medium. A possible filter material may have a hole / slot or mesh width in the range between 60 μm and 2000 μm, in particular between 200 μm and 800 μm.
It may also be provided in special embodiments, that the insert has a lower opening, which, however, is completely or partially covered by such a filter material.

For degassing, the vacuum tank is usually connected to an exhaust. The suction power used in this case can be in the range between 20 and 200 standard m ³ / h, in particular between 40 and 80 standard m ³ / h per m ³ volume of the vacuum vessel, usually at an absolute pressure of less than 100 mbar. In this case, an advantageous mode of operation is that the suction capacities when starting the vacuum ventilator are comparatively high in order to be able to realize practicable evacuation times (in the range 10 [s] to 10 [min], preferably 1-5 [min]). Normal operation can then take place at a lower suction power.

• 1 bis 3 zeigen jeweils einen Schnitt durch eine Vorrichtung gemäß verschiedener Aspekte der Erfindung.
• 4a zeigt einen Einsatz und 4b einen Teil eines Einsatzes gemäß weiterer Aspekte der Erfindung.

The invention will be further explained with reference to schematic, not to scale figures.

• 1 to 3 each show a section through a device according to various aspects of the invention.
• 4a shows a bet and 4b a part of an insert according to further aspects of the invention.

1 shows a device for degassing a medium in the form of a coating color with a vacuum container 1 with a container wall 1a , Container bottom 1b and container lid 1c , The vacuum tank has an inlet 10 for the coating color as well as in its bottom 1b an outlet 12 for the degassed coating color. Via a vacuum connection 11 is the vacuum container 1 connected to a vacuum generator. At the in 1 shown embodiment are sensors 9 in this connection 11 provided, for example, with which the extracted gas volume or the volume flow can be measured. These measured values can be used for controlling the control of the degassing device.

Inside the vacuum container 1 is a rotation element 2 intended. This includes a number of turntables 22 . 22a working on a common wave 21 are fixed so that they are rotatable about a common axis. As indicated in the figure can be advantageously provided that one or all turntable 22 . 22a are provided on its outer circumference with a cylindrical screen surface. Will paint over an inlet 10 placed on a rotating turntable, so this is outward to the vessel wall 1a accelerated and thereby already degassed. To prevent the accelerated coating color on the container wall 1a impinges and possibly damaged by continuous abrasion, is an application 3 provided, which between the rotation element 2 , in particular the turntables 22 . 22a and the container wall 1a is arranged that during operation of the device accelerated medium to the use 3 rebounds. The in 1 shown use 3 is open at the bottom, thus allowing the degassed medium to run out to the bottom of the container 1b , There it forms at the n 1 shown embodiment, a reservoir 7 of coating color. On the inside of the insert 3 are installations for conducting 31 of the medium in the form of baffles 31 intended. Coating color from a first turntable 22 to the insert 3 is thrown through a baffle 31 on a lower second turntable 22a directed. Through the second turntable 22a The coating color is accelerated again and thereby vented. Depending on the application, a large number of such cascade stages can be provided. In the 1 There are five turntables 22 . 22a but it can also be shown 6 . 8th or more turntables 22 . 22a be used.
There is usually an optimum fill level of the coating color in the operation of such devices 8th , which is also referred to here as "100% level" 8. The use 3 in 1 It reaches down so far that it enters the reservoir of coating color 7 dives, if this until the 100% level 8th is filled. As the use 3 Usually static, and not with the rotation element 2 with rotated, this is not a problem. In the area of the 100% level 8th includes the in 1 shown embodiment, a cooling device 5 , This can for example by a cooling hose 5 be realized, the one around the vacuum tank 1 is placed. Alternatively, cooling devices that are integrated in the wall of the vacuum container or other suitable cooling devices 5 be used. Also the provision of insulation 5 can be beneficial.
Especially for missions 3 that like in 1 shown in the reservoir 7 dipping on coating color, it is very beneficial when in use 3 one or more suction openings 6 are provided, so that the applied vacuum also inside the insert 3 takes effect. One possibility is it, the suction 6 in the wall of the insert 3 provided. They may, for example, be mounted so that they pass through the baffles 31 are shielded so that they are not clogged by coating color, and that also no coating color can penetrate through them to the outside. If between use 3 and the container wall 1a a gap d is provided additionally facilitates the uniform pressure distribution in the interior of the vacuum vessel 1 ,

A vacuum container 1 , as in 1 can usually be shown by opening or lifting the container lid 1c be opened. Often both the rotation element 2 as well as the use 3 on this container lid 1c attached and can share with him from the vacuum tank 1 be removed. If between use 3 and the container wall 1a a gap d is provided, this facilitates the removal in addition. As the use 3 and the rotation element 2 from the vacuum tank 1 can be removed, easy maintenance, especially in the form of a cleaning is possible.
In the 2 shown device is different from 1 essentially by having only a very small reservoir 7 is provided on coating color, and the 100% level 8 just above the Behälterboden1b. The outlet 12 is expediently mounted centrally here. The use 3 is here designed to be flexible extension elements 3b was added, which now dip into the coating color, and possibly the container bottom 1b touch. The extension element (s) 3a can advantageously be carried out easily removable. On a cooling and / or insulation was in the device in 2 omitted here.
3 shows by way of example that the rotation element 2 not necessarily turntable 22 , 22a must include. Here is the coating color through an inlet 10 in a rotating container 23 where it is raised by the centrifugal forces on the sloping wall and is thereby vented. At the top of the container 23 The coating color is thrown outwards again, which is why again a suitable use 3 is provided. The device is in 3 not as a reservoir 7 used, although this is possible. Of the 3 in 3 shown use, is such that he can not dive into a possibly existing reservoir.

4a shows a possible embodiment of an insert 3 , the four segments 301 . 302 . 303 . 304 comprises, or is composed of these. These four segments 301 . 302 . 303 . 304 are releasably connected to each other eg by means of quick-release fasteners. If needed, appropriate seals may be provided between the segments. At the top of each segment 301 . 302 . 303 . 304 are holding devices 310 attached to the insert on the container ceiling 1c to be able to attach: 4a continues to show that on the insert 3 Also means for easy installation and removal in the form of handles 320 and guardrails 330 can be provided. In this embodiment, these attachments shown both purposes simultaneously. In 4b is a section of one of the segments described above 301 to see. Since advantageously all segments are identical, only one is shown here. In particular, the baffles can be seen here 31 for directing the coating color. Such an assignment 3 is in particular with a rotation element 2 advantageous, which as in 1 and 2 with turntables 22 . 22a Is provided. The use 3 also works well with extension elements 3a be combined.

LIST OF REFERENCE NUMBERS

1

vacuum vessel

1a

container wall

1b

container bottom

1c

container lid

2

rotating member

3

commitment

3a

renewal

5

Means for cooling or insulation

6

suction

7

reservoir

8th

100% level

9

sensor

10

inlet

11

vacuum connection

12

outlet

21

axis

22,22a

turntable

23

container

31

baffles

200

opening

301,302,

segments

303.304

segments

310

holder

320

handle

330

Guardrail

(D)

gap

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 2832071 A [0002]
• DE 19939275 A1 [0002]
• DE 102005017952 A1 [0002]
• EP 1078670 A1 [0002]
• WO 03/002227 A1 [0002]
• EP 0735913 B1 [0002]
• DE 4009042 C2 [0002]
• EP 1798333 [0002]

Claims (12)

Apparatus for degassing a liquid to pasty medium, in particular a coating color for coating paper or cardboard with a vacuum container (1) having an inlet (10) for the medium to be degassed and a vacuum connection (11) or vacuum generator and an outlet (12 ) for the medium to be degassed. and inside the vacuum container (1) there is further provided a rotary member (2) rotatable about an axis (21) adapted to accelerate the medium towards the container wall (1a) of the vacuum container (1), characterized in that in the interior of the vacuum container (1) there is furthermore provided an insert (3) which is arranged between the rotary element (2) and the container wall (1a) so that the medium accelerated during operation of the device bumps completely or partially against the insert (3) , Device after Claim 1 , characterized in that the insert (3) is open at the bottom, to allow a flow of the medium to the container bottom (1b) of the vacuum container. Device according to one of the preceding claims, characterized in that the rotation element (2) comprises at least one, in particular a plurality of turntables (22, 22a). Device according to one of the preceding claims, characterized in that the insert (3) has internals (31) for conducting the medium. Device according to one of the preceding claims, characterized in that the rotation element (2) comprises at least a first (22) and a second turntable (22a), wherein the first turntable is disposed above the second turntable, and the insert (3) internals (31 ) for directing the medium, which are arranged so as to guide medium that has been thrown from the first turntable (22) against the insert (3) onto the second turntable. Device according to one of the preceding claims, characterized in that the insert (3) has one or more suction openings (6) through which a pressure equalization between the interior of the insert (3) and the remaining vacuum container (1) can take place. Device according to one of the preceding claims, characterized in that the insert (3) and / or the rotatable rotation element (2) is or are attached to a container lid (1c) of the vacuum container (1). Device according to one of the preceding claims, characterized in that means for easy installation and removal of the insert (3), in particular in the form of guide rails are provided. Device according to one of the preceding claims, characterized in that between the insert (3) and the container wall (1a), a gap (d) is provided. Device according to one of the preceding claims, characterized in that the insert (3) consists of a plastic, in particular a fiber-reinforced plastic, a metal or a combination of these materials. Device according to one of the preceding claims, characterized in that the insert (3) consists of several parts which are detachably connected to each other. Device according to one of the preceding claims, characterized in that means (5) for at least partial cooling and / or isolation of the vacuum container (1) are provided.

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