CA2280216C

CA2280216C - A clean-water outlet

Info

Publication number: CA2280216C
Application number: CA002280216A
Authority: CA
Inventors: Herbert Brauchli
Original assignee: Degremont SA
Current assignee: Suez International SAS
Priority date: 1998-08-12
Filing date: 1999-08-10
Publication date: 2008-11-04
Anticipated expiration: 2019-08-10
Also published as: EP0979668A3; EP0979668B1; DK0979668T3; CA2280216A1; DE19836563A1; ATE346667T1; PT979668E; DE59914019D1; ES2275324T3; EP0979668A2

Abstract

The present invention relates to a clean-water outlet, in particular for the discharge of clean water from SBR plants, having a float, a closable outlet element disposed thereon which possesses an inlet section for the supply of the clean water into the outlet element and having a discharge line connected to the outlet element for the discharge of the clean water. A reliably sealing clean-water outlet which possesses no mechanically actuated parts to close the outlet element, is provided in that the inlet section is designed in such a way that it can be closed by means of an air or gas cushion, that means are provided by means of which the air or gas cushion can be generated in the inlet section and that a deaerator is provided by means of which the air or gas cushion can be eliminated from the inlet section.

Description

A CLEAN-WATER OUTLET
Field of the Invention The present invention relates to a clean-water outlet, in particular for the discharge of clean water from SBR plants, having a float, a closable outlet element disposed thereon which possesses an inlet section for the supply of the clean water into the outlet element and having a discharge line connected to the outlet element for the discharge of clean water. In this instance, the semi-batch reactor or SBR is being used as one element in a waste water treatment installation. SBR's are used in a wide variety of chemical processes, and are commonly used in waste water treatment installations.

Background of the 'Invention Such clean water outlets are frequently used in SBR water treatment plants, and are used therein at the end of the biological treatment of the waste water, for example at the end of the cycle for an SBR to discharge or decant the water treated during such a cycle. The clean water outlet therefore must be capable of ensuring draining-off of the treated water, and of retaining the biomass in the SBR, so that it is available for use in subsequent treatment cycles. Generally during the clean-water discharge step, the biomass is largely in a sedimented state, with a small part floating upon the clean water surface.

-2-Accordingly, there is a demand on an optimum clean-water outlet that this be disposed in a floating manner in order to ensure the greatest possible distance to the sedimented sludge at all times. Furthermore, a clean-water outlet must be of a closable design.
This makes it possible only to open the outlet when clean water is to be discharged, whereas in the other phases, i.e. during the activation and mixed phases, it is fully closed. This prevents any sludge penetrating and being taken into the outlet during the clean-water discharge.

Due to the fact that the sludge is also present in part as float, an ideal clean-water outlet must also meet the task of discharging the water not directly at.the .water surface, but below it in order to retain the floating sludge accordingly.
Further, the clean-water outlet must be designed in such a way that the flow rates are limited during the discharge of the water so that sedimented sludge is not whirled along.

Generic clean-water outlets are known which possess a float and a discharge wo.ir disposed below the surface of the water. The discharge weir is connected to a hose or pipe line through which the clean-water supplied to the discharge weir is discharged.
To meet the required closability of the clean-water outlet, the discharge weir in clean-water outlets of the prior art is closed by means of a mechanism disposed above the float and opened only as required, i.e. during decanting. In such a clean-water outlet, it is a disadvantage that, on the one hand, mechanical parts are needed to open and close the clean-water outlet and that, on the other hand, the leak-proofness of the outlet cannot be reliably guaranteed, in particular after longer use, due to wear phenomena.
Summary of the Invention It is therefore the object of the present invention to further develop a generic clean-water outlet in such a way that this possesses no mechanically moving parts at all to open and close the outlet and also closes reliably after longer operation.

-3-This object is solved on the basis of a generic clean-water outlet by the inlet section being designed in such a way that it can be closed by means of an air or gas cushion, by means being provided by means of which the air or gas cushion can be generated in the inlet section and by a deaerator being provided by means of which the air or gas cushion can be eliminated from the inlet section. A clean-water outlet of such a design meets the demands given above and furthermore possesses the advantage that no mechanically moving parts are needed to close the clean-water outlet or the outlet element. Rather, the closing is based on the creation of an air or gas cushion which is disposed in such a manner in the inlet section of the outlet element that this can be reliably closed and accordingly prevents water from penetrating the discharge element.

A further advantage over clean-water outlets of the prior art results from the fact that the wear of sealing elements, which can lead to the clean-water outlet having corresponding leaks, is of no importance in the present case as the closing effect is achieved exclusively by the air or gas cushion in accordance with the invention.

In accordance with a preferred aspect of the present invention, the inlet section is disposed between the outlet element and the float.

It is of particular advantage if the outlet element is designed as a discharge weir. The inlet section of the clean-water outlet can be formed by the overflow edge of the discharge weir and a groove-shaped recess of a component of the clean-water outlet disposed opposite the discharge weir. Accordingly, in accordance with the invention, an air or gas cushion is formed in the groove-shaped recess to close the clean-water outlet, by means of which the access of water via the overflow edge of the discharge weir is effectively prevented.

-4-In accordance with a preferred aspect of the present invention, the component disposed opposite the discharge weir is the float of the clean-water outlet.
Instead of this, it is equally possible to provide any other component which possesses a corresponding groove-shaped recess on its side allocated to the overflow edge.

In accordance with a first aspect of the present invention, there is provided a clean-water outlet for extraction of clean water below the surface of the water in a plant, comprising (i) a float having a closable outlet element disposed thereon and an inlet section for feeding the clean water into the outlet element;
(ii) a discharge line connected to the outlet element for discharging the clean water;
(iii) a generating means for generating an air or gas cushion in the inlet section; and (iv) a venting means for extraction of the air or gas cushion from the inlet section, wherein the inlet section is constructed and arranged to be closable by means of the air or gas cushion.

In another aspect of the present invention, it is provided that the deaerator comprises a valve. The means to generate an air or gas cushion can comprise a compressor.

In accordance with a preferred aspect of the present invention, means can be provided, by means of which the float and the outlet element can be fixed in a horizontal position. This is advantageous particularly for the reason that the centre of gravity of the clean-water outlet in accordance with the present invention is pushed upwards by the air cushion generated from time to time, whereby the stable position of the clean-water outlet in the water is impaired.

- 4a -Two guide elements running parallel and rotatably disposed on the clean-water outlet and a mounting device can be provided, the distance of the rotating axles on the mounting device and the clean-water outlet being identical and the connecting lines of the rotating axles on the mounting device and the clean-water outlet running in parallel. The guide elements are disposed in the sense of a parallelogram, by means of which it is also ensured that the horizontal orientation of the outlet element and of the float is maintained irrespective of the level of the water.

It is particularly advantageous if one of the guide elements is formed by the discharge line.

In a further aspect of the present invention, it is provided that at least one of the guide elements is hinged to the clean-water outlet and to the mounting device at two points in each case.

-5-Brief Description of the Drawings Further details and advantages of the present invention are described by means of an embodiment shown in the drawing in which Fig. I shows a schematic cross-section view of the cleari-water outlet in accordance with the invention in a closed state and. during the decanting phase;

Fig. 2 shows a schematic representation of the clean-water outlet in accordance with the invention in a side view and a top view;

Fig. 3 shows a schematic representation of a generic clean-water outlet of the prior art;

Fig. 4 shows a schematic representation of a clean-water outlet of the prior art having a decanter disposed below the water's surface;

Fig. 5 shows a schematic representation of a clean-water outlet of the prior art having a discharge bath which can be lowered into the tank.

Fig. 6 shows a schematic representation of a clean-water outlet of the ,prior art having a siphon; and Fig. 7 shows a schematic representation of a clean-water outlet of the prior art having a telescoping discharge line.

Detailed Description Fig. I shows in a schematic cross-section view the clean-water outlet in accordance with the invention in the closed state (top) and during the decanting phase (below).

-6-Below the float 10, the discharge weir 30 is disposed which possesses the circumferential overflow edge 32. In its lower region disposed opposite the overflow edge 32, the float 10 possesses the groove-shaped recess 12. The inlet region 20 of the discharge weir 30 is accordingly limited by the overflow edge 32 and the groove-shaped recess 12.

Furthermore, a compressor 50 is provided which is connected by a flexible line to the float 10, lines for the supply of the compressed air to the groove-shaped recess 12 being provided inside the float 10.

The discharge weir 30 is connected at its lower region to the discharge,line 40, by which the clean water supplied to the discharge weir 30 is let out therefrom.

As Fig. 1, bottom, illustrates, a valve 60 is further provided which is connected to the air or gas lines extending in the float 10 and connecting to the groove-shaped recess 12. In Fig. 1, top, the valve 60 and in Fig. 1, bottom, compressor 50 is not shown.

If the discharge weir 30 is to be closed, compressed air or any gas mixture is led by means of the compressor 50 and the lines extending therefrom into the groove-shaped recesses 12, with a corresponding air or gas cushion being created therein.
Here, the overflow edge 32 of the discharge weir 30 is disposed in accordance with the invention in such a way that an overflow over this edge 32 by clean water is impossible when the groove-shaped recess 12 is filled with the air or gas mixture.

The discharge line 40 further possesses a stop element (not shown) preferably disposed outside the clean-water tank which is only opened when clean water is to be discharged.

-7-If clean water is now to be decanted, the valve 60 shown in Fig. 1, bottom, is opened, whereby the air or the gas is eliminated from the groove-shaped recess 12 and the inlet section 20 is released for the passage of water. The water flows in accordance with the arrows shown in Fig. 1, bottom, first through the inlet section 20 into the discharge weir 30 and is discharged therefrom through the discharge line 40.

Fig. 2, top, shows in a schematic side view, guide elements 40, 80 running in parallel and disposed on the clean-water outlet and the mounting device 70. Here, the guide element 40 is formed by the discharge line 40. Both guide elements 40, 80 are rotatably connected by the rotating axles 85 with the clean-water outlet and the mounting device 70. The distance of the rotating axles 85 on the mounting device 70 and the clean-water outlet is identical. Furthermore, the connecting lines of the rotating axles 85 on the mounting device 70 and on the clean-water outlet are disposed in parallel to each other. The rotating axles 85 thus determine the four corner points of a parallelogram. By means of such an arrangement, it is achieved thatthe discharge weir 30 is always held in a horizontal position or that the clean-water outlet is always held in the plane described in Fig. 2, top, by Y-Y, irrespective of the water level.

Fig. 2, bottom, shows that the guide element 80 on the clean-water outlet and on the mounting device 70 is hinged in each case at two points 85. It therefore results that any moving possibility of the clean-water outlet is no longer given in the plane X-X.
Figs. 3 to 7 show clean-water outlets of the prior art.

Fig. 3 shows a generic clean-water outlet with a float 10 and a discharge weir disposed thereunder. The discharge weir 30 is opened and closed by means of a valve to be actuated mechanically, the valve actuation being effected by the mechanism 90 located above the float 10. The discharge weir 30 is connected to the discharge line 40 for the discharging of the clean water.

-8-Fig. 4 shows a decanting device in which the clean-water discharge is always performed under the water's surface. Here, there is the disadvantage that during the aeration and mixing, the closing of the discharge line 40 is impossible, which leads to the fact that at these times, sludge can penetrate the discharge line.

Fig. 5 shows a clean-water outlet in which an outlet bath 100 can be lowered into the tank by means of a mechanical lowering device 110 while at the other times, the bath 100 is raised outside the tank. In such a clean-water outlet, there is a disadvantage in that the outlet bath 100 is always travelled through the float layer during the lowering and during raising always takes up float and removes it from the tank.

The clean-water outlet of Fig. 6 comprises a siphon 120 by means of which water can be discharged from the tank. Here, the disadvantage results that, on the one hand, the possible lowerings of the water level are limited and, on the other hand, the distance to the float level is not optimum.

Fig. 7, finally, shows a clean-water outlet in which the clean water is discharged via a discharge weir 30 which is mounted on floats 10 and is accordingly always held at the water's surface in this way. In this clean-water outlet, the discharge line 40 has a telescope-like design and is telescoped together by a corresponding amount when the water level falls. Here, the disadvantage results that the seal of the discharge lines 40 connected together in a telescope-like manner, can only be designed with limitations with the result that sludge can penetrate the discharge line 40. Furthermore, the possible lowering of the water level is limited.

Claims

WE CLAIM:

1. A clean-water outlet for extraction of clean water below the surface of the water in a plant, comprising (i) a float having a closable outlet element disposed thereon and an inlet section for feeding the clean water into the outlet element;
(ii) a discharge line connected to the outlet element for discharging the clean water;
(iii) a generating means for generating an air or gas cushion in the inlet section; and (iv) a venting means for extraction of the air or gas cushion from the inlet section, wherein the inlet section is constructed and arranged to be closable by means of the air or gas cushion.

2. A clean-water outlet according to Claim 1, wherein the inlet section is disposed between the outlet element and the float.

3. A clean-water outlet according to Claim 1 or Claim 2, wherein the outlet element is in the form of a discharge weir.

4. A clean-water outlet according to Claim 3, wherein the inlet section is formed by an overflow edge of the discharge weir and a groove-shaped recess of an opposing component of the clean-water outlet disposed opposite the discharge weir.

5. A clean-water outlet according to Claim 4, wherein the opposing component is the float.

6. A clean-water outlet according to any one of Claims 1 to 5, wherein the venting means includes a valve.

7. A clean-water outlet according to any one of Claims 1 to 6, wherein the generating means includes a compressor.

8. A clean-water outlet according to any one of Claims 1 to 7, further comprising means to retain the float and the outlet element in a horizontal position.

9. A clean-water outlet according to Claim 8, further comprising an attachment device, two guide elements comprising substantially parallel axles and being rotatably disposed on the clean-water outlet and on the attachment device, whereby a distance between the axles on the attachment device and on the clean-water outlet is substantially identical, and the connection lines of the axles extend substantially parallel on the attachment device and on the clean-water outlet.

10. A clean-water outlet according to Claim 9, wherein at least one of the guide elements is formed by the discharge line.

11. A clean-water outlet according to Claim 9 or Claim 10, wherein at least one of the guide elements is hingedly connected to each of the clean-water outlet and the attachment device.

12. A clean-water outlet according to any one of Claims 1 to 11, wherein the plant is a semi-batch reactor.