Aeration installation

2C~0~36 Aeration Installation Description The invention concerns an aeration installation for injecting a gas into a liquid, in particular, into to be treated waste water.

These types of aeration units are, among others, for raw content aeration of waste water, for introducing air or oxygen into activating basins or for sludge stabilizion, for aerating rivers, lakes and fish ponds, but also, for example, for neutralizing liquids by gassing with carbon dioxide.

These types of aeration units are known essentially in two modes of rendition, namely pipe and so-called surface or disk aerators.

The invention is concerned with the latter group.

'~ 2~0Q~36 In the DE-PS 34 10 267, is described a disk aerator that consists of a foundation with at least one gas opening as well as a gas-permeable membrane cover over the foundation and attached to the foundation, in which a means for limiting the filling out of the membrane in the gassing state is disposed in the area of the gas opening, one end of which is attached to the membrane and operating in conjunction with its other end to a counterpiece located in the area of the opening.

With such a installation, the membrane should be "held down" in the area of gas feed, thereby a more even gassing intensity is strived for.

It is obvious that the known "stroke limiting device" is relatively complexly constructed and, most of all, also takes away a considerable portion of the gassing surface of the membrane, namely in the area in which the highest gassing intensity is normally reached.

The goal of the present invention is to develop a specific aeration installation in such a way that the optimal gassing intensity and evening out over the gassing surface is achieved. In the process, the aeration installation should preferably be of a simple construction, and be formed in such a way that known gassing means can also be supplemented.

To solve the task presented, the invention makes use of the following knowledge: It was conflrmed 2C~ 36 that an optimal gassing intensity and evenness can be achieved particularly in those sections of the gaspermeable membrane in which the membrane shows the greatest angle of curvature. This is particularly true for perforated membranes. In such a membrane, the individual perforation openings open namely only at a certain angle of curvature, while they are practically closed in the un-deformed state. Such a mode of rendition of a membrane is preferred in order to guarantee that in the non-gassing state the membrane is more or less dense and the liquid cannot enter into the aeration installation and thus into the gas supply line.

The invention therefore aims to form the gaspermeable part of the aeration installation in such a way that the largest possible surface sections are available as a gassing surface and within these surface sections the largest possible areas are elastically deformable in such a way that large curvature radii can be formed.

This results in the further knowledge that the actual gassing surface should preferably be divided into various individual sections.

In its most general mode of rendition, the aeration installation has the following characteristics:

- a foundation, - at least a partially deformable cover attached to the foundation, and - at least one gas supply means in the area between foundation and cover, with 2~0(~36 - the cover divided into sections of different deformability (different deformation properties) - at least the sections of greater deformability (in this case: under gas pressure) having 5openings for the gas.

While in the current state of the art (DE-PS 34 10 267) the membrane arranged on the foundation is formed over the entire surface with a material of constant characteristics and physical property values, the aeration installation according to the invention is distinguished thereby in that the cover has sections of different material characteristics (physical property values). This is achieved, in particular, through different moduli of elasticity in various sections.

Hereby the following effect is obtained: In the gassing state, the sections with the higher modulus of elasticity, i.e. the less deforamble sections remain more or less stable in shape in comparison to the non-gassing state, while the more elastic : sections positioned in between are able to form in a known ways and means.

Heresby the gassing surface that is in one part in the current state of the art is thus divided into -numerous partial gassing surfaces which at times, per se, yield optimal gassing qualities.

The construction of the cover according to the invention can be produced in various ways and means.

After an initial mode of rendition, the less .35 deformable sections are formed linearly or staggered 2~ 36 between the surface sections with lower modulus of elasticity. In this way, the more or less nondeformable areas only comprise a small part of the overall gassing surface, and thus only unessential sections of the gassing surafce are lost.

But even, according to the invention, they can in turn be formed with gas openings in such a way that practically the entire cover is then available a as gassing surface.

To obtain particularly favorable gassing conditions, the less deformable sections, especially in the case of disk aerators, should be constructed as rings arranged at intervals from each other.

These rings can either be concentric and spaced at intervals to each other or, however, also be formed as individual rings at intervals to each other.

In the first case, ring disk shaped sections of the membrane are formed between the rings, which deform as a ring-shaped tunnel in the gassing state.

In the latter case, the elastic sections each have a circular shape and in the gassing state, lead to the formation of half shells.

In all modes of rendition, the less deformable sections serve as boundaries for the deformed porous intermediate areas.

These unelastic sections can simply consist of a material quality of greater specific weight.

2~0(~-36 For example, in the case of a cover of a rubberquality, the unelastic sections can be formed by being reinforced with metal pieces. For example, according to an advantageous mode of rendition of the invention, metal rings or slats can be vulcanized into the corresponding places.

It is even easier if the corresponding sections is of a hard rubber quality fulfilling the same function, for example, while the more elastic sections arranged in between are formed from an easily deformable rubber consistancy with perforations. The modulus of elasticity can also be modified by having the areas that are to be deformed less formed thicker than the other membrane sections.

In the aforementioned mode of rendition examples the cover can be designated as one part. But it is also possible to form the covering as several parts, with the less elastic sections formed by a part with surface breaks, attached to the edge of the foundation, and the more elastic sections are formed by a membrane with perforations or the like, arranged between foundation and the part, which is fixed on the edge of the part and/or the foundation.

In this way, the less elastic part can consist of a metal or plastic plate or a metal or plastic basket, for example. The membrane connected to the foundation is then preferably formed in such a way that, in the non-gassing state, it lies opposite the metal or plastic part. But if gas is introduced through the gas supply means, z~n~36 _ 7 the membrane can then form upwards into the area of the breaks of the plate or the basket (i.e. away from the foundation) and similar configurations then come about as in the models described at the beginning with slat~ integrated in the membrane.

If the plate has several round breaks, the membrane will thus form through the breaks in the formatlon of a hemispherical shape.

It is always guaranteed that a number of surface sections with high radius of curvature are formed, which is favorable for the gassing intensity due to the effects described at the beginning.

The membrane can of course also be arranged between two metal or plastic parts of the aforementioned type.

The effect obtained is the same.

To obtain the most even distribution of gas, a gas distibuting space is preferably formed between the foundation and the cover. In the simplest case, this can take place with either the foundation being formed like a disk (then the cover can easily be constructed as a simple plate) or the foundation is more or less flat and the covering is then formed like a basket, with the covering then having its opening edge facing downwards towards the foundation and attached to it.

The gas supply means is preferably arranged in the middle to obtain an even gas distribution on all sides. Naturally, `- 2000236 8 27560-20 several gas supply means can also be arranged spread out over the gassing surface.

The advantages to be had with the aeration installation according to the invention are obvlous. By subdlvidlng the gasslng surfaces a number of lndlvldual aeration sections are formed, each dlsplaylng optlmal aeratlon characterlstlcs, partlcularly wlth a section with a large radlus of curvature.

Practlcally the entlre gasslng surface ls ~vallable for gasslng and unused surfaces are largely elimlnated.

Known aeratlon lnstallatlons can be supplemented at any tlrne by slrnply changlng the coverlng (membrane).

Every type of llmltlng devlce, etc. ls ellmlnated.

In accordance wlth the present lnventlon there ls provlded an aerator comprlslng a base lncluding a gas lnlet, a flexlble membrane secured on said base so as to form an lnlet chamber therebetween, sald membrane comprlsing at least one integrally formed, relatlvely rlgld, lmperforate rlng-shaped portlon surrounded by more easlly deformable perforated portlons adapted to bulge outwardly durlng lnflatlon.

In accordance wlth the present lnventlon there ls also provlded an aerator comprlslng a base including a gas inlet a flexible membrane secured on said base so as to form an inlet chamber therebetween, sald membrane comprislng at least one lntegrally formed, relatlvely rlgld rlng-shaped portlon surrounded by more easily deformable perforated portlons adapted to bulge outwardly durlng lnflatlon.

Further characterlstics of the invention result from the B characteristlcs of the sub-clalms as well as the other - 2000236 8a 27560-20 registratlon documents.

Below, the invention is descrlbed in greater detail using two examples of rendition, with extremely simplified crosssection (lengthwise) illustrations. Identical components or those with identical functions are identified with the same reference numbers in the figures.

Fig. 1 shows a first embodiment of an aeration lnstallatlon in a sectional view Fig. 2 shows a second embodiment of an aeration installation in a sectlonal vlew The aeration installatlon according to Flgure 1 consists of a dish-shaped foundation 10, the circular B 2t~ 36 g lid 12 of which has an opening 14 in its middle from which a gas supply line 16 runs downwards. The foundation 10 and its parts consist of a glass fiber reinforced plastic.

A cover 18 runs above the lid 12 and is shaped, in this example, as a membrane with perforations .

The membrane 18 i9 pulled around the outer edge 20 and is attached to the foundation 10 there by means of a muzzle hoop 22.

As can be seen from the drawing, a ring-shaped slat 24 runs in the area of the membrane 18, with a greater material strength than the membrane 18.

While the membrane 18 consists of a highly elastic rubber material, the ring-shaped slat 24 is formed by a hard rubber incorporated into the membrane 18.

Instead of one slat, several slats or another configuration of the connecting elements can be used or selected. It is also possible to form the slat from the same material as the other parts of the covering, i.e. also of rubber, but - as shown thicker than the membrane sections. A higher modulus of elasticity of the slat 24 compared to the membrane 18 results from thickening the material and leaving out the perforation.

In the non-gassing state, the membrane 18 has the position marked I in relation to the foundation 10.

A small aeration space 26 is created between the membrane 18 and the lid 12 of the foundation 10.

If a gas, for example oxygen, is then introduced under pressure into the aeration space 26 through the gas supply line 16 and the opening 14, a deformation Z~ 36 of the elastic sections 18', 18 " of the membrane 18 is caused, with the ring-shaped sectlon 18' of the membrane 18 forming upwards as a ring-shaped tunnel, while at the same time the circular section 18'' of the membrane 18 takes on a hemispheric shape.

Due to the largely non-elastic characteristics of the slat (hard rubber ring) 24 it hardly gets deformed at all and essentially maintains its original shape even in the gassing condition marked by the figure II.

It is to be understood from the form of the membrane 18', 18'' according to II that large areas of the membrane have a pronounced radius of curvature which provides for an optimal and even gassing.

The aerator shown in Figure 1 is used for raw-content aeration of a waste water, for example, and arranged on the botton of the waste water container in such a way that a stream of oxygen exiting through the perforation of the membrane 18, 18', 18 " can pass upwards into the liquid.

Without the formation of the essentially non-elastic ring-shaped slat 24, there would be a single bellshaped forming of the membrane 18 and thus only to a slight surface section of greater curvature roughly in the middle above the opening 14.

It is obvious that through the forming of the membrane with elastic and non-elastic or more and less elastic sections according to the invention, a division of the gas stream in the sense of an optimal gas supply into the liquid can be obtained.

2~ 36 In the example of rendition according to Figure 2, the foundation 10 is tub-shaped and has a bottom 28 from which a ring-shaped partition 30 extended upwards. An opening 14 is arranged with a gas supply line 16 in the middle of the bottom 28.

The aeration space 26 is already formed inside the foundation lO through this construction.

The upper edge of the foundation 10 is marked with the reference figure 32. On the ring-shaped partition 30, a ring-shaped clamp connection 34 is positioned which is for taking up the covering or membrane 18 on the one hand, and is also for taking in the stiff plastic plate 36 that is arranged parallel to and at a slight distance from the membrane (in the non-gassed state). In the process the plastic plate 36 runs somewhat above the membrane 18.

The plastic plate 36 has altogether nine circular openings 38 between which plastic slats 40 are formed.

If gas, for example oxygen, is then introduced through the gas supply line 16 or the opening 14 into the aeration space 26, the oxygen first spreads evenly in this space 26 before it is pressed further upwards through the perforated membrane 18 or the opening 38 of the plastic plate 36.

The elastic membrane 18 is pressed through the openings 38 upwards forming altogether Z~ 36 12 nine hemispherical sections of which five sections 18', 18'', 18" ', 18' " ' and 18''" ' can be recognized in Figure 2.

Similarly to Figure 1 the arrangement of the membrane 18 in the non-gassing state is represented by the figure I, in the gassing state by the figure II.

The stiff slats 40 make sure the plastic plate 36 is not also deformed in the case of gassing.

Through the openings 38 in the plastic plate 36, instead of the a single bell-shaped deformation of the membrane 18 through the geometric shape according to the invention, there i9 a dividing into altogether nine bell-shaped sections and thus an even and optimal gassing of the waste water.

After switching off the gas supply, the membrane 18 returns, in both cases due to its elastic characteristics, to the position marked I. Thereby inputting water under force into the aeration space 26 or the gas supply 16 is prevented at the same time if, as is the case in the example of rendition, the membrane 18 is formed with very small perforation holes that are practically closed in the un-deformed state and only first open in the deformation state.