GASSING DEVICE

Abstract

A gassing device for the intermittent introduction of oxygen-containing gas or air into the waste water of a sewage treatment plant includes at least one membrane and a support body supporting the membrane and having gas-inlet openings. The membrane comprises a support membrane and a gassing membrane, wherein through-openings are arranged in the support membrane and continuous perforation slits are arranged in the gassing membrane and connected to the through-openings of the support membrane, or project into same, or are arranged inside the through-openings. The gassing membrane has a greater elasticity and is softer than the support membrane. The width of the through-openings of the support membrane decrease from the outer side and the gassing membrane projects partially or completely into the through-openings of the support membrane, and has a corresponding negative contour in relation to the through-openings of the support membrane.

Claims

1. A gassing device (10) for the intermittent introduction of oxygen-containing gas or air into a liquid or the waste water of a sewage treatment plant, comprising at least one membrane (16) and a support body (12) having gas inlet openings (14), which body carries the membrane, wherein the membrane (16) comprises a support membrane (18) and a gassing membrane (20), passage openings (30) are disposed in the support membrane (18), and continuous perforation slits (38) are disposed in the gassing membrane (20), the perforation slits (38) of the gassing membrane (20) follow the passage openings (30) of the support membrane (18) or project into these or are disposed within the passage openings (30), and the gassing membrane (20) demonstrates greater elasticity and is softer than the support membrane (18), wherein the passage openings (30) of the support membrane (30) decrease, in terms of their inner width, from the outer side (34) that faces the waste water to the inner side (36) that faces the gas feed, and that the gassing membrane (20) projects into the passage openings (30) of the support membrane (18) in the region of its perforation slits (38), in whole or in part, and has a corresponding negative contour relative to the passage openings (30) of the support membrane (18).

2. The gassing device (10) according to claim 1, wherein the passage openings (30) of the support membrane (18) are configured conically as a cone or a truncated cone or a pyramid or a truncated pyramid.

3. The gassing device (10) according to claim 1, wherein the gassing membrane (20) and the support membrane (18) consist of a composite material.

4. The gassing device (10) according to claim 3, wherein the composite material is a particle composite material or a layer composite material.

5. Gassing device (10) according to claim 1, wherein the gassing membrane (20) covers the upper side (34) of the support membrane (18), which side faces the waste water, over its full area.

6. The gassing device (10) according to claim 1, wherein the gassing membrane (20) consists of a plurality of inserts, which are individually disposed in the passage openings (30) of the support membrane (18).

7. The gassing device (10) according to claim 1, wherein the support membrane (18) has a Shore A hardness of greater than 60.

8. The gassing device (10) according to claim 1, wherein the support membrane (20) has a Shore A hardness of less than 60.

9. The gassing device (10) according to claim 1, wherein the gassing membrane (20) is an ethylene-propylene-diene rubber (EPDM), a nitrile rubber (NBR nitrile butadiene rubber), a silicone, a polyurethane (PU).

10. The gassing device (10) according to claim 1, wherein the perforation slits (38) are configured in line shape or cross shape or star shape.

11. The gassing device (10) according to claim 1, wherein the support body (12) or the support membrane (18) has spacer elements (22) in the form of a support matrix on the side that faces the support membrane (18) or the support body (12).

12. The gassing device (10) according to claim 11, wherein the membrane (16) is free of passage openings (30) and perforation slits (38) in the region of the gas inlet openings (14) of the support body (12).

Description

[0055] Further developments and advantageous embodiments of the invention are evident from the following descriptions of exemplary embodiments, which are shown in the drawing. The drawing shows:

[0056] FIG. 1: a schematic sectional view of a partial region of a gassing device according to the invention,

[0057] FIG. 2: as a detail of FIG. 1, a schematic sectional view of a membrane of the gassing device, in the original, unused state,

[0058] FIG. 3: as a detail of FIG. 1, a schematic sectional view of a membrane of the gassing device, during operation with the gas feed turned on, and

[0059] FIG. 4: as a detail of FIG. 1, a schematic sectional view of a membrane of the gassing device, during operation with the gas feed shut off.

[0060] When the same reference numbers are used in FIGS. 1 to 4, these refer to the same parts, so that for the purpose of avoiding repetition, a component that has already been described does not need to be discussed again in every figure description.

[0061] FIG. 1 shows a schematic sectional view of a partial region of a gassing device 10 according to the invention. A membrane 16 is mounted on a support body 12 having a gas inlet opening 14, which membrane in turn consists of a support membrane 18 and a gassing membrane 20. The support membrane 16 has spacer elements 22 on its side facing the support body 12, which elements are disposed in the form of a support matrix. These spacer elements 22 create a permanent interstice 28 between the upper surface 24 of the support body 12 and the lower surface 26 of the support membrane 18, and thereby the gas supplied through the gas inlet opening can spread out completely into the space 28 between the support body 12 and the support membrane 16, and does not first have to prepare its path to the passage openings and perforation slits by lifting the membrane. The gas inlet 14 that is shown, however, is situated in a region of the membrane 16 that is free of passage openings and perforation slits. In this way, it is prevented that the supplied gas does not preferentially seek the shortest exit path, but rather can first spread out uniformly to the other passage openings and perforation slits, before being transferred to the liquid.

[0062] FIG. 2 shows, as a detail of FIG. 1, a schematic sectional view of a membrane of the gassing device, in the original, unused state.

[0063] Passage openings 30 are disposed in the support membrane 18, only one of which openings is shown in this figure and the following figures, in each instance. The inner walls 32 of the passage opening 30 run from the outer side 34, which faces the liquid, to the inner side 36, which faces the gas supply side, in a slanted progression, approximately in the shape of a V. The clear width of the passage openings 30 therefore narrows from the outer side 34 to the inner side 36. From a spatial point of view, this involves restriction of a cone or truncated cone.

[0064] This passage opening 30 is filled with the material of the gassing membrane 20. The gassing membrane 20 therefore does not extend continuously over the entire outer surface of the support membrane 18, in the preferred embodiment, but rather is restricted solely to the passage openings 30 of the support membrane 18, as individual islands. The gassing membrane 20 and the support membrane 18 form a composite material, in other words the boundary layers are intimately connected with one another and also remain so during operation as intended, and can only be separated by means of destruction. The gassing membrane 20 and the support membrane 18 differ with regard to their elasticity and softness. While the gassing membrane 20 is highly elastic and soft, the support membrane 18 behaves in comparatively inelastic and hard manner, in other words almost as a rigid body. These different properties are achieved by means of different materials or different additives in similar or the same basic materials.

[0065] The gassing membrane 20 has a central perforation slit 38, which extends from the inner surface 36, from which the gas is supplied, to the outer surface 34, at which the liquid is present. The perforation slit 38 can be configured in line shape or cross shape or star shape, in detail.

[0066] FIG. 3 shows, as a detail of FIG. 1, a schematic sectional view of a membrane of the gassing device, during operation with the gas feed turned on. In this case, the pressure that acts on the inner wall 36 of the membrane 16 and thereby also on the gassing membrane 20 is greater than the hydrostatic pressure of the liquid that acts on the outer wall 34 of the gassing membrane 20 from the outside. Due to the pressure difference, the gassing membrane 20 expands slightly outward, and at the same time stretches at the conical boundary layers 32 toward the support membrane 18 due to its elasticity and softness. In this regard, the perforation slit 38 opens, so that gas can flow through and gas bubbles can exit and pass over into the liquid. Doming and stretching of the gassing membrane 20 takes place over a very small path distance, so that no lasting over-stretching and undesirable wrinkle formation can occur after the gas feed is shut off, in the relaxed state.

[0067] This is also achieved in that only a small attack surface from the direction of the inner side 32 of the membrane 16 is present due to the conical configuration or the configuration as a truncated cone. The support membrane 18 behaves comparatively significantly more rigidly, and therefore practically does not support deformation of the gassing membrane 20 at all. Furthermore, the configuration and property with regard to elasticity and softness of the gassing membrane 20 allows very good metering of the gas amount that is transferred to the liquid, as a function of the pressure. In this regard, the microbubble nature is maintained within broad limits.

[0068] FIG. 4 shows, as a detail of FIG. 1, a schematic sectional view of a membrane of the gassing device, during operation with the gas feed shut off.

[0069] In this case, the hydrostatic pressure of the liquid column which is in effect from the outer side 34 of the membrane 16 is greater than the pressure on the inner side 36 of the membrane 16. Since the surface that faces outward toward the liquid is large, due to the geometric configuration of the gassing membrane 20, the hydrostatic pressure of the liquid can exert a great force on the gassing membrane 20, and this leads to a shift toward the inner side 36 of the membrane and to the walls of the perforation slits 38 being pressed together, in the case of the conical shape. At the same time, in this regard, the surface of the gassing membrane 20 that faces the outer side 34 is dented in slightly. Due to the conical shape, the force with which the walls of the perforation slits 38 are pressed against one another is directly dependent on the hydrostatic pressure, so that the sealing effect is also maintained with an increasing hydrostatic pressure. In this case, however, no expansion takes place, but rather shrinkage of the gassing membrane 20 takes place, in other words in the other direction from its neutral state as compared with expansion. Unilateral stress, which could lead to brittleness and fatigue of the material, is thereby prevented.

REFERENCE SYMBOL LIST

[0070] 10 gassing device [0071] 12 support body [0072] 14 gas inlet opening [0073] 16 membrane [0074] 18 support membrane [0075] 20 gassing membrane [0076] 22 spacer elements [0077] 24 upper surface [0078] 26 lower surface [0079] 28 interstice [0080] 30 passage opening [0081] 32 inner wall of the passage opening [0082] 34 outer side [0083] 36 inner side [0084] 38 perforation slit