EP2374527B1 - Gassing device for intermittent feeding of a gas into a liquid - Google Patents

Description

The invention relates to a gassing device for the intermittent introduction of a gas into a liquid according to the preamble of patent claim 1.

A gassing device according to the preamble of claim 1 is already by the document EP 1 129 768 B1 known, from which the invention proceeds.

The known gassing device comprises a tubular introduction body with a lower axially extending groove for longitudinal distribution of the gas to be introduced. The introduction body is surrounded by a membrane of elastic material which comprises perforated areas with perforation slots for introducing the gas into the liquid. In addition, in the lower part, where the axial groove of the introduction body is located, the membrane has an area which is not perforated. The purpose of the missing perforation in the region of the axial groove is to prevent an immediate exit of the gas supplied via the groove through the covering membrane in the groove area. Rather, an overpressure should build up, the membrane forming an annular space for a Recirculating gas distribution from the inlet body lifts and thereby allows access of the gas to the perforation slots and thus a discharge of the gas over a larger area.

Usually fumigation facilities are used in wastewater treatment plants to introduce gases into wastewater. In this case, the gassing is not operated continuously, but intermittently. The reason for the intermittent gas introduction is the treatment concept in sewage treatment plants for certain types of wastewater. The treatment concept is based on the fact that first of all the activity of bacteria, primarily aerobics, is used to breathe organic substances, d. h., To convert them into low-molecular compounds, ultimately in carbon dioxide, water, nitrates and sulfates. Prerequisite for this in aerobic systems is adequate ventilation of the activated sludge in the wastewater. Then the ventilation is suspended and the biological wastewater treatment with anaerobes, d. H. Bacteria that live on the chemically bound oxygen and thus reduce reductively gain in importance.

In practice, it has been found that it is because of the intermittent operation in the breaks, in which no gas is introduced into the liquid or in the wastewater and the membrane is then no longer inflated by a gas cushion between its inside and the outside of the introduction body and no Annulus more between the introduction body and the membrane is, leads to a wrinkling of the membrane in the upper region.

When switching off the gassing, so if no gas is introduced into the liquid causes the hydrostatic pressure of the liquid that the membrane is pressed against the introduction body. Since this does not always happen evenly, there is an uncontrolled wrinkling of the membrane, preferably in the region of the perforation slots. This area is somewhat less stiff than the non-perforated area of the membrane.

The wrinkling is also supported by the fact that the membrane in comparison to the outer circumference of the introduction body has an oversize, so that the circumference of the membrane in the relaxed state is greater than the outer circumference of the introduction body. Due to the oversize of the membrane, the assembly of the gassing is to be facilitated because the membrane can then easily slide over the introduction body without resistance.

The membrane has because of the oversize so-called "excess material", which inevitably leads to wrinkling. When switching off the gassing the excess material is absorbed by the fold. The wrinkling of the membrane is basically to be regarded as disadvantageous, because the fold of the material of the membrane is claimed to kink and it is an internal stress in the material of the membrane produced. As a result, the material becomes brittle at the location of the crease. This results after a longer period of operation after multiple switching on and off the gassing that the membrane ruptures or breaks at the location of the fold. The gassing unit is then no longer operational, and it is necessary to remove the gassing unit from the liquid and to replace the damaged membrane with a new membrane.

In the known gassing device, the operating life of the membrane is prolonged by reducing the tendency to crack by enforcing a controlled wrinkling in the region of the membrane which is free of perforation slits and therefore not already weakened. For this purpose, in the known gassing device in an axially extending groove opposite region means are provided, which force a fold of the membrane in this axially extending groove opposite region with shut off gas supply, which is free of perforation slots.

With the gassing device designed in this way, a substantial extension of the service life of the membrane could be achieved. Nevertheless, in individual cases a membrane at the site of wrinkles on embrittlement of the material after a long time still tear.

The invention has for its object to provide a gassing, the membrane remains virtually free of cracking tendency and embrittlement despite the intermittent operation, and their service life can thus be significantly extended over previously known solutions.

The solution of this problem is achieved by the features stated in the characterizing part of patent claim 1.

Further developments and advantageous embodiments of the invention will become apparent from the dependent claims.

In the invention according to claim 1, the convex elevation, in conjunction with the subsequent concave transitions, results in the shortest enclosure of the introduction body being followed by tangents which span the concave transitions. In contrast, the unwound outer circumference following the contour of the introduction body is longer than the shortest covering. This embodiment thus creates space for a membrane whose inner circumference is greater than the shortest enclosure. Excess material of the membrane can under hydrostatic pressure depending on the degree of excess to the concave Create transitions. The membrane remains wrinkle-free as long as its inner circumference is smaller than the unwound outer circumference of the introduction body. By specifying the height of the apex and the apex radius of the convex elevation and the inner radius of the concave transitions a harmful kinking of the membrane is avoided. Cracking or embrittlement of the material of the membrane is thus prevented, whereby the service life of the membrane and thus the gassing is significantly extended.

An advantage of the invention is also that membranes can be used with greater tolerances of the inner circumference. Until now, only tightly tolerated membranes had to be used, which resulted in high reject rates during production. Membranes which lose elasticity due to aging can also be used, since a permanent elongation can be compensated for by a loss of elasticity in that a larger contact surface is provided for the installation of the membrane on the introduction body under the hydrostatic pressure.

Since, in the invention, the membrane remains completely free of wrinkles after switching off the gas supply, the membrane could be perforated in addition to the lateral areas in the assembled state, even in the upper region. However, then there is the possibility that the under the hydrostatic pressure in the concave transitions depressed material is stretched and consequently the perforation slots Open there and let liquid penetrate into the annulus between the membrane and the introduction body. Since this effect is undesirable, the upper portion of the membrane, which encloses the convex elevation in conjunction with the subsequent concave transitions of the introduction body, remains unperforated. But this happens for other reasons than in the prior art.

According to a further development, the peak height of the convex elevation is between 0.19 and 0.23 of the radius of the base contour, the peak radius between 0.063 and 0.096 of the radius of the base contour and the concave transitions between the convex elevation and the surface of the base contour each have an inner radius of 0.476 of the radius of the basic contour.

These restricted dimensional ranges represent an optimization determined in test series compared to the fields specified in claim 1.

In a first practical embodiment with a radius of the basic contour of the introduction body of 31.5 mm, the peak height is 7 mm, the apex radius 2 mm and the inner radius of the concave transitions 15 mm. The membrane has an inner circumference of a minimum of 205 mm to a maximum of 206.08 mm.

In a second practical embodiment with a radius of the basic contour of the introduction body of 31.5 mm, the peak height is 6 mm, the apex radius 3 mm and the inner radius of the concave transitions 15 mm. The membrane has an inner circumference of a minimum of 205 mm to a maximum of 206.08 mm.

Furthermore, transitions between the groove and the outer circular base contour are rounded and have a radius of 2 to 4 mm, preferably a radius of 3 mm.

Under the influence of the hydrostatic pressure, the membrane may also partially submerge in the groove. The rounded transitions here also avoids kinking of the membrane.

Fig. 1

eine Querschnittsansicht einer Begasungseinrichtung zum intermittierenden Einbringen eines Gases bei eingeschalteter Gaszufuhr als nicht maßstäbliche Prinzipdarstellung der Erfindung,

Fig. 2

eine Querschnittsansicht gemäß Fig. 1, jedoch bei abgeschalteter Gaszufuhr,

Fig. 3

eine Querschnittsansicht des Grundkörpers einer Begasungseinrichtung gemäß einem ersten Ausführungsbeispiel der Erfindung und

Fig. 4

eine Querschnittsansicht des Grundkörpers einer Begasungseinrichtung gemäß einem zweiten Ausführungsbeispiel der Erfindung.

The invention will be explained in more detail with reference to the embodiments illustrated in the drawings. Show it:

Fig. 1

a cross-sectional view of a gassing device for the intermittent introduction of a gas when the gas supply is turned on as a non-scale schematic diagram of the invention,

Fig. 2

a cross-sectional view according to Fig. 1 , but with the gas supply switched off,

Fig. 3

a cross-sectional view of the body of a gassing according to a first embodiment of the invention and

Fig. 4

a cross-sectional view of the body of a gassing device according to a second embodiment of the invention.

In Fig. 1 a gassing device 10 is shown which consists of an introduction body 12 and a membrane 16 surrounding the introduction body 12. The membrane 16 has lateral perforated areas 18, 20 with perforation slots 22 and further areas 24, 25 which are not perforated and have no perforation slots 22.

The lower region 25 covers an axially extending groove 14 in the introduction body 12. This groove 14 serves for the longitudinal distribution of the gas to be introduced. The reason for the lack of perforation in the lower region 25 is to prevent an immediate exit of the gas supplied via the groove 14 through the covering membrane 16 in the lower region of the groove 14. It's supposed to be one Overpressure build, which lifts the membrane 16 to form an annular space for a circulating gas distribution from the introduction body 12 and thereby allows access of the gas to all perforation slots 22, thus allowing a leakage of the gas over a larger area of the membrane 16.

Opposite the lower groove 14, a convex elevation 28 is provided on the upper side on the surface 26 of the introduction body 12. This convex elevation 28 does not abruptly merge into the surface 26 of the introduction body 12, but rather has concave transitions 30, 32 on both sides. In consideration of the convex bump 28 and the concave transitions 30, 32 between the convex bump 28 and the surface 26 of the introduction body 12, the outer periphery of the introduction body 12 is increased from the normal circular shape. The so-called unwound circumferential length of the diverging from the circular introduction body 12 is now greater or at least as large as the inner circumference of the membrane 16th

The effect of the convex bump 28 in conjunction with the concave transitions 30, 32 is in FIG Fig. 2 to recognize, which shows the gassing device 10 with switched off gas supply. Due to the hydrostatic pressure of the gas surrounding the device 10 and not shown here, the membrane 16 is pressed against the introduction body 12. In the lower region 25, the hydrostatic pressure is higher than in the upper region 24, so that the Application of the membrane 16 against the introduction body 12 initially begins in the lower region 25 and then propagates through the regions 18, 20 to the upper region 24. Since the outer circumference of the introduction body 12 by the convex elevation 28 and taking into account the concave transitions 30, 32 is deliberately increased so far that the outer circumference or the unwound circumferential length of the introduction body 12 is greater than or at least as large as the inner circumference of the membrane 16 sets the membrane 16 completely without wrinkling in all areas of the introduction body 12 at. When the membrane 16 abuts the introduction body 12, the perforation slots 22 are closed.

The above-mentioned "excess material" of the membrane 16 is practically taken up by the concave transitions 30, 32 and the convex elevation 28, in contrast to the known gassing device, in which the excess material is taken up by a fold. Since in the invention, the membrane 16 no longer forms a fold over its entire circumference, the material of the membrane 16 is also claimed at any point to kink. The life of the membrane 16 is thereby significantly extended.

Fig. 3 shows a first embodiment of the invention with concrete dimensions. These dimensions are within the ranges specified in claims 1 and 2 and represent proven optimizations in practice.

In both embodiments, the radius 38 of the basic contour of the introduction body 12 is 31.5 mm. Starting from this basic contour, the crown height 34 is 7 mm, the peak radius 36 2 mm and the inner radius 40 of the concave transitions 30, 32 15 mm in the first embodiment. In both embodiments, the membrane 16 has an inner circumference of a minimum of 205 mm to a maximum of 206.08 mm.

Fig. 4 shows a second embodiment of the invention, in which the apex height 34 6 mm, the apex radius 36 3 mm and the inner radius 40 of the concave transitions 30, 32 15 mm.

In these embodiments, the minimum inner circumference of the membrane is greater than a developed outer circumference of a through the surface 26 of the base contour with the convex elevation 28 and tangents 44, 46 between the convex elevation 28 and the surface 26 of the base contour instead of the concave transitions 30, 32nd The peripheral difference between the tangents 44, 46 and the concave transitions 30, 32 forms the reserve for receiving the excess material of the membrane 16. This means at the same time that the membrane 16 may not be larger than the unwound outer circumference the surface 26 of the base contour including the concave transitions 30, 32, when wrinkling is to be avoided safely.

As already mentioned, the application of the membrane 16 against the introduction body 12 first begins in the lower region 25. As a result, the membrane 16 could be pressed into the groove 14. To prevent the diaphragm 16 from kinking between the surface 26 of the base contour and the groove 14, transitions between the groove 14 and the outer circular base contour may be rounded and have a radius between 2 and 4 mm, preferably a radius of 3 mm.

LIST OF REFERENCE NUMBERS (is part of the description)

10

gassing

12

Introduction body

14

groove

16

membrane

18

Area (perforated)

20

Area (perforated)

22

Perforationsschlitze

24

Area (not perforated)

26

Surface basic contour

28

Convex elevation

30

concave transition

32

concave transition

34

peak height

36

vertex radius

38

Radius basic contour of the inlet body

40

Radius concave transition

42

Radius transition groove

44

tangent

46

tangent

Claims (5)

1. A gassing device (10) for intermittent introduction of a gas into a liquid, with at least one tubular feed-in body (12) with an outer circular basic contour (26), from which there deviate an axially running groove (14), which is at the bottom in the installed state, for longitudinally distributing the gases to be fed in and, diametrically opposite the groove (14), an axially running convex projection (28), which is at the top in the installed state, and with a membrane (16) made of an elastic material, which surrounds a surface shell of the feed-in body (12) and includes perforated regions (18, 20) with perforation slots (22) for feeding the gas into the liquid and two unperforated regions (24, 25) situated above the groove (14) and the projection (28), characterised in that a crest of the convex projection (28) protrudes over the outer circular basic contour of the feed-in body (12) by a crest height (34) between 0.15 and 0.3 of the radius (38) of the surface (26) of the basic contour, has a crest radius (36) between 0.03 and 0.1 of the radius (38) of the surface (26) of the basic contour and concave transitions (30, 32) between the projection (28) and the surface (26) of the basic contour each have an inner radius (40) between 0.4 and 0.6 of the radius (38) of the surface (26) of the basic contour and that the membrane (16), in the unstressed state, has an inner periphery of which the dimension is smaller than an unwound outer periphery of an outer contour of the feed-in body (12) formed by the surface (26) of the basic contour with the convex projection (28) and the concave transitions (30, 32), but larger than an unwound outer periphery of an outer contour of the feed-in body (12) formed by the surface (26) of the basic contour with the convex projection (28) and tangents (44, 46) between the convex projection (28) and the surface (26) of the basic contour instead of the concave transitions (30, 32).
2. The gassing device according to claim 1, characterised in that the crest height (34) of the convex projection (28) is between 0.19 and 0.23 of the radius (38) of the basic contour, the crest radius (36) is between 0.063 and 0.096 of the radius (38) of the basic contour and the concave transitions (30, 32) between the convex projection (28) and the surface (26) of the basic contour each have an inner radius (40) of 0.476 of the radius (38) of the basic contour.
3. The gassing device according to claim 1 or 2, characterised in that, in a first embodiment with a radius (38) of the basic contour of the feed-in body (12) of 31.5mm, the crest height (34) is 7mm, the crest radius (36) is 2mm and the inner radius (40) of the concave transitions (30, 32) is 15mm and that the membrane (16) has an inner periphery of a minimum of 205mm to a maximum of 206.08mm.
4. The gassing device according to claim 1 or 2, characterised in that, in a second embodiment with a radius (38) of the basic contour of the feed-in body (12) of 31.5mm, the crest height (34) is 6mm, the crest radius (36) is 3mm and the inner radius (40) of the concave transitions (30, 32) is 15mm and that the membrane (16) has an inner periphery of a minimum of 205mm to a maximum of 206.08mm.
5. The gassing device according to claim 1 or 2, characterised in that transitions between the groove (14) and the outer circular basic contour are rounded and have a radius of between 2 and 4mm, preferably a radius of 3mm.

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