WO1996009989A1

WO1996009989A1 - Aerator with improved efficiency

Info

Publication number: WO1996009989A1
Application number: PCT/BE1994/000063
Authority: WO
Inventors: Johny Hector Haegeman
Original assignee: Haegeman J H
Priority date: 1994-09-28
Filing date: 1994-09-28
Publication date: 1996-04-04
Also published as: AU7648794A

Abstract

The invention relates to a device for the aeration of liquids consisting of a power source (1) which drives a propeller element (6, 7) consisting of a centrifugal screw impeller formed by a screw (7) which starts approximately from below on a center shaft (2) and extends upwards curved in the form of a spiral and wherein an outwardly bent deflector (6) is attached at the top so that liquid is drawn up and dispersed over the liquid surface (9). Above the turned back body the device comprises means whereby the reduced pressure created by the flow of liquid is used for the aspiration of air and to counteract damage to the motor as a result of the reduced pressure.

Description

FOR THE PURPOSES OF INFORMATION ONLY

Codes used to identify States party to the PCT on the front pages of pamphlets publishing international applications under the PCT.

AT Austria GB United Kingdom MR Mauritania

AU Australia GE Georgia MW Malawi

BB Barbados GN Guinea NE Niger

BE Belgium GR Greece NL Netherlands

BF Burkina Faso HU Hungary NO Norway

BG Bulgaria IE Ireland NZ New Zealand

BJ Benin IT Italy PL Poland

BR Brazil P Japan PT Portugal

BY Belarus KE Kenya RO Romania

CA Canada KG Kyrgystan RU Russian Federation

CF Central African Republic KP Democratic People's Republic SD Sudan

CG Congo of Korea SE Sweden

CH Switzerland KR Republic of Korea SI Slovenia

CI Cote d'lvoire KZ Kazakhstan SK Slovakia

CM Cameroon Liechtenstein SN Senegal

CN China LK Sri Lanka TD Chad cs Czechoslovakia LU Luxembourg TG Togo cz Czech Republic LV Latvia TJ Tajikistan

DE Germany MC Monaco TT Trinidad and Tobago

DK Denmark MD Republic of Moldova UA Ukraine

ES Spain MG Madagascar US United States of America

FI Finland ML Mali uz Uzbekistan

FR France MN Mongolia VN Viet Nam

GA Gabon DESCRIPTION

Aerator with improved efficiency

This invention relates to devices which are used for the aeration of liquids, particularly water. These devices consist of a power source, generally a motor, which drives a shaft to which a paddle element is attached and wherein the device is often mounted fixed above the water to be treated or is mounted on a float.

In the new generation of devices the paddle element consists of a screw pump, wherein in the most efficient devices the screw pump has the form of a centrifugal screw pump, consisting of a screw which starts substantially from below on the central shaft of the paddle element and runs upwards in the form of a spiral. This central shaft is provided at its top end with an outwardly bent turned-back body which is approximately trumpet- shaped. Water is pumped up by the screw pump and is dispersed substantially horizontally over the water surface.

In these devices the motor is usually attached to a fixed plate or disc-shaped element which is situated above the turned-back body and which also contributes to the further deflection of the pumped-up water stream, the motor shaft to which the paddle element is attached passing through an opening in this plate or disc. Nevertheless, it should be noted that in the zone near the outflow of water from the turned-back body a reduced pressure is created by the flow of the water in the space between the motor and the turned-back body. This reduced pressure also makes its effect felt in the motor - via the removal of lubricant from the bearings - and can cause damage to the motor by depleting the bearing lubricant and drawing in water or moist air via the condensate outlet. Secondly, this reduced pressure at the same time causes particles of dirt to be discharged into the space below the motor. The object of the present invention is to overcome these disadvantages and at the same time to introduce air and oxygen into the water and consequently also to improve the efficiency of these devices.

According to the main characteristic of the invention, the reduced pressure created in the space above the turned-back body is used for the aspiration of air, so that an air current is produced and consequently an enhanced introduction of air into the outflow zone of the water is obtained.

According to the invention, this air current can be obtained by bringing the space between the motor and the mounting plate into contact with the atmosphere.

According to one embodiment of the invention, this contact with the atmosphere can be effected by distance elements provided between the motor and the mounting plate of the motor. These distance elements create openings by means of which the air current is mixed at the level of the turned-back body with the water stream. This enhanced introduction of air into the water stream increases the efficiency of the device by a considerable extent.

According to another embodiment, this air current can be improved even further by providing blades above the turned-back body.

According to another embodiment the air current can be increased even further by making use of the cooling fan effect; for this purpose a casing can be provided around the motor and the air can be led in via this casing.

Moreover, the efficiency of these devices can be further improved by designing the screw pump according to the application concerned, the size of the basin to be treated, the type of contaminated water, the ambient temperature, etc. Thus it is possible to provide the screw pump over the entire length of the shaft or merely over sections thereof. The speed, diameter and the number of turns of the screw can be adapted to suit, the screw can be single-threaded or multiple-threaded. The screw can also be 3 panly single-threaded and paπly multiple-threaded. The screw can thus have extra blades near the lowest part to enhance the pumping effect, but may also have extra blades near the water surface to enhance the centrifugal force for dispersing the water. All possible variants of screw pumps can be used within the scope of the present invention.

A further improvement in efficiency can be obtained by optimising the induced movement of the water by the provision of guidance means on the device in the vicinity of the water aspiration zone which convert the direction of rotation of the water into a combined horizontal and vertical rotational movement. These guidance means consist of screw-shaped or flat plates which are provided at a suitable angle around the device.

The invention is described in more detail below in terms of non-limiting examples of embodiments and with reference to the accompanying drawings, where:

Figure 1 is a schematic illustration of an aerator constructed according to the prior art, showing a detail of the outlined portion;

Figure 2 is a partial schematic representation of an aerator according to the invention, showing a detail of the outlined portion:

Figure 3 is a schematic representation of an embodiment of an aerator with counter-blades;

Figure 4 is a schematic representation of an aerator with air aspiration via the motor;

Figure 5 is a schematic representation of an aerator with distance elements and an improved screw pump; and

Figure 6 is a schematic representation of an aerator with distance elements and improved water circulation. In the Figures referred to below, the same components are denoted by the same reference numerals for the sake of simplicity.

Referring to Figure 1 , this illustrates a prior art surface aerator consisting of a motor 1. a float 3, a pump housing 4, an aspiration cone 5 and a stabilisation body 12. The motor 1 is attached to the float 3 by means of a flanged transition piece 8. The top end of the central shaft 2 of the propeller element 6, 7 is widened and forms an outwardly bent turned-back body 6. A double-thread screw 7 is provided around the central shaft 2 of the propeller element 6, 7.

When the motor is started, the screw 7 draws up water which is dispersed approximately horizontally via the turned-back body 6 over the water surface 9. The outflow of the water generates a reduced pressure in the zone 11 near the turned-back body 6. This reduced pressure is communicated to the space 13 below the motor 1 where the lubricant outlet 14 leads out, and can propagate into the inside 16 of the motor 1 via the lubricant outlet 14 of the motor bearing and can come into contact with the atmosphere via the condensate outlet 15. This causes moisture and particles of dirt to be drawn into the motor, the consequence of which is damage to the windings and the bearings.

Figure 2 shows an aerator similar to that illustrated in Figure 1 , but which is provided with means which make use of the reduced pressure for introducing air. In this example the underside 23 of the motor 1 is attached to the top plate 25 of the flanged transition piece 8 via distance elements 24. By this means air is drawn in via the space 26 between elements 23 and 25. The reduced pressure created by the outflow of water in zone 11 is sufficient to draw in an air current via the space 26. The disadvantages of damage or the deposition of dirt in the motor are avoided. The aspirated air increases the oxygen content of the water dispersed on the water surface, due to which the efficiency of the aerator is significantly improved.

Figure 3 illustrates another embodiment. This Figure shows that the top edge 39 of the turned-back body 6 and the top plate 25 of the flanged transition piece 8 are separated from each other. Because the flanged transition piece 8 is fixed and the turned-back 5 body 6 rotates, there is a space between the two. If there are then one or more openings 36 in the top plate 25 of the flanged transition piece 8, air is drawn in according to the invention via these openings into zone 11 as a consequence of the reduced pressure in zone 11. This aspiration effect is enhanced by counter-blades 37 provided between the top edge 39 of the turned-back body 6 and the top plate 25 of the flanged transition piece 8. These counter-blades 37, which rotate with the shaft 2. considerably improve the aspiration effect in zone 11.

Figure 4 shows an aerator similar to that illustrated in Figure 2. but in this embodiment air is drawn in around the motor. The motor 1 is surrounded by a casing 41, and the air which is drawn into zone 11 according to the invention emerges from the space formed between the motor 1 and the casing 41. This air can thus also serve as a cooling medium if the suction force in zone 11 is great enough so that the aspirated air is sufficient to cool the motor 1 satisfactorily. Due to this effect, the classical cooling means (fan 42) can be omitted and additional motor capacity becomes available. Moreover, due to its cooling effect this air contains energy which is usefully employed in the dispersion of water over the water surface.

According to a variant, cooling of the motor is effected in the classical manner, namely by means of a fan 42. Because the motor 1 is surrounded by a casing 41 the heated cooling air is guided into zone 11 , whereby the pressure effect due to the fan increases the through-flow of air into zone 11.

Figure 5 illustrates a variant of Figure 3, in which the aerator comprises a centrifugal screw impeller. The screw consists of a continuous screw blade 51, an auxiliary screw blade 52 at the bottom end of the screw blade construction and an auxiliary screw blade 53 at the top end near the turned-back body 6 of the screw blade construction. Due to the auxiliary screw blade 52 the aspiration effect of the pump is enhanced and due to the auxiliary screw blade 53 the centrifugal force of the impeller is increased, but frictional losses and turbulence are kept low. 6

It is clear that this screw blade construction can assume all possible forms, but always comprises at least one continuous screw, wherein one or more screw blades are present either at the bottom end, at the top end, or at both ends.

Figure 6 illustrates a variant of Figure 2, in which the aerator comprises screw-shaped guidance means 61 around the pump housing and aspiration cone, whereby a rotational movement having both a horizontal and a vertical component is imparted to the water. It is clear that the guidance means can be placed solely round the pump housing and/or aspiration cone or can optionally be placed round the centrifugal screw impeller if no pump housing or aspiration cone is present. Moreover, the guidance means do not have to be screw-shaped and can also consist of flat plates.

It is clear that all these variants and embodiments can be used separately or in combination. For example, the blades 37 shown in Figure 3 can thus be combined with the casing 41 illustrated in Figure 4, or the blades 37 can be combined with the improved screw pump shown in Figure 5 or with the improved water circulation according to Figure 6, etc., without falling outside the scope of this invention.

It is also clear that the invention is not restricted to the examples described above, which for the sake of simplicity illustrate various possible ways of increasing the air supply or individual aerators.

There is a large number of variants as regards the manner in which the propeller element is placed on the shaft of the motor. From these variants, one skilled in the art will select the most appropriate place to provide an air passage. The effect which is sought for the particular application is obtained by increasing the air supply near the zone where the water is dispersed and where the so-called venturi effect predominates.

The air flow can be improved by various technical means, blades or the provision of a casing round the motor merely being examples thereof. 7

This invention is also not restricted to the aerators described, but can be applied to every aerator of the type which has a propeller element which disperses water over the water surface.

Claims

1. A device for the aeration of liquids consisting of a power source ( 1 ) which drives a propeller element (6, 7) consisting of a centrifugal screw impeller formed by a screw (7) which starts approximately from below on a central shaft (2) and extends upwards curved in the form of a spiral, and wherein an outwardly bent turned-back body (6) is attached at the top so that liquid is drawn up and dispersed over the liquid surface (9), characterised in that means (24, 26, 37, 41 , 42) are provided above the turned-back body whereby the reduced pressure created by the flow of liquid is used for the aspiration of air.

2. A device according to claim 1. wherein the power source ( 1) is fastened to a mounting plate (25), characterised in that a space (26) which is in contact with the atmosphere exists between the power source ( 1) and the mounting plate (25).

3. A device according to claim 2, characterised in that the contact of the space (26) with the atmosphere is effected by distance elements (24).

4. A device according to claim 3, characterised in that blades (37) are provided above the turned-back body (6).

5. A device according to one or more of claims 1 to 4. characterised in that a casing (41) is provided around the power source (1) and that air is drawn in via the space between the power source (1) and the casing (41).

6. A device according to one or more of claims 1 to 5, characterised in that the screw (7) consists of a screw blade construction which comprises at least one continuous screw and at least one auxiliary screw blade at the top and/or bottom end.

7. A device according to one or more of claims 1 to 6, characterised in that guidance means which impart a combined horizontal and vertical rotational movement 9 to the liquid are provided around the centrifugal screw impeller (6. 7), the pump housing (4) and/or the aspiration cone (5).