Title of Invention

STIRRING DEVICE FOR ACTIVATED SLUDGES

Abstract The invention relates to a stirring device for activated sludges comprising a stirring body (2) attached to a shaft (1) and having a hyperboloid wall (3), further comprising an air supply line (5, 8) for supplying air to a funnel-like recess (6) formed on a bottom of the stirring body (2). In order to improve the entry of air into the fluid medium surrounding the stirring body (2), the invention provides for an opening of the recess (6) formed on the bottom be covered with a covering element (7) such that an annular gap (10) having a predetermined width remains uncovered between an outer circumferential surface (9) of the stirring body (2) and the covering element (7) and for the air supply line (8) to be guided coaxially through the cover element (7) relative to the shaft (1).
Full Text COMPLETE SPECIFICATION
[see section 10 and rule13]
“STIRRING DEVICE FOR ACTIVATED SLUDGES”
Name and address of the applicant: INVENT UMWELT-UND
VERFAHRENSTECHNIK AG, Am Pestalozziring 21, 91058 Erlangen, Germany
Nationality: Germany
The following specification particularly describes the nature of the invention and the
manner in which it is to be performed.
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TECHNICAL FIELD
The invention relates to a stirring device for activated sludges.
BACKGROUND
Such a stirring device is known from DE 42 18 027 A1. With the known stirring device, air
is supplied to a funnel-like recess on an underside of a hyperboloid-like stirring body via
an air supply line. Shear ribs with which the supplied air is distributed in the surrounding
activated sludge in the form of little air bubbles are provided on a lower circumferential
boundary. Studies have shown that a size distribution of the air bubbles created by this is
not particularly homogeneous. During this, undesirably large air bubbles are also created
occasionally.
STATEMENT OF THE DISCLOSURE
Accordingly the present disclosure provides a stirring device for activated sludges
contained in a basin comprising a stirring body (2) having a hyperboloid-like the stirring
device shaped wall (3) attached to a shaft (1) and an air supply line (5, 8) running along the
bottom (4) of the basin to supply air, wherein a vertical section (8) of the air supply line
points to a funnel-like recess (6) formed on an underside of the stirring body (2)
characterized in that an opening of the recess (6) formed on the underside is covered with a
covering element (7) in such a way that an annular gap (10) with a specified width remains
free between a lower circumferential surface (9) of the stirring body (2) and the covering
element (7), and that the vertical section (8) of the air supply line (8) is led coaxially
through the covering element (7) in relation to the shaft (1).
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail using examples based on the drawings.
Figure 1: A schematic cross sectional view of a first stirring device,
Figure 2a: A schematic cross sectional view of a second stirring device,
Figure 2b: A further schematic cross sectional view as per Fig. 2a,
Figure 3: A schematic cross sectional view of a third stirring device,
Figure 4: A schematic cross sectional view of a fourth stirring device and
Figure 5: A schematic cross sectional view of a fifth stirring device.
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DETAILED DESCRIPTION
The present disclosure relates to a stirring device for activated sludges contained in a basin
comprising a stirring body (2) having a hyperboloid-like the stirring device shaped wall (3)
attached to a shaft (1) and an air supply line (5, 8) running along the bottom (4) of the
basin to supply air, wherein a vertical section (8) of the air supply line points to a funnellike
recess (6) formed on an underside of the stirring body (2) characterized in that an
opening of the recess (6) formed on the underside is covered with a covering element (7) in
such a way that an annular gap (10) with a specified width remains free between a lower
circumferential surface (9) of the stirring body (2) and the covering element (7), and that
the vertical section (8) of the air supply line (8) is led coaxially through the covering
element (7) in relation to the shaft (1).
In an embodiment of the present disclosure further shear ribs (19) are provided on a
radially outer section of an outer side of the further stirring body (18).
In another embodiment of the present disclosure the shaft (1) is led through the stirring
body (2) and is held on its one end in a safety bearing (13) provided in the covering
element.
In yet another embodiment of the present disclosure the covering element is held rotatably
in a safety bearing (13) surrounding the air supply line.
The invention relates to a stirring device for activated sludges as defined in the preamble of
claim 1.
The object of the invention is to eliminate the disadvantages in accordance with prior art.
In particular, a stirring device for activated sludges is to be specified with which air
bubbles with a bubble size distribution as homogeneous as possible can be created in a
liquid surrounding the stirring body.
This object is solved by the features of claim 1. Useful embodiments of the invention result
from the features of claims 2 to 13.
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According to the provisions of the invention, it is provided that an opening of the recess
formed on an underside is covered with a covering element in such a way that an annular
gap with a specified width remains free between a lower circumferential surface of the
stirring body and the covering element, and that the air supply line is led coaxially through
the covering element in relation to the shaft. Due to the provision of the covering element
suggested by the invention, the air supplied to the recess is now supplied through the
annular gap in the area of a circumferential boundary of the stirring body. The formation of
air bubbles with an undesirably large bubble diameter can be counteracted by suitable
selection of the specified width of the annular gap. A particularly homogeneous bubble
distribution in the liquid medium surrounding the stirring body can be created. Leading the
air supply line coaxially in relation to the shaft through the covering element ensures that
the air supplied to the recess essentially only escapes again through the annular gap. The
size distribution of the air bubbles generated by the suggested stirring device is
distinguished by a relatively small, average bubble diameter and by a monomodal size
distribution.
In an advantageous embodiment of the invention, the annular gap has a width in the range
from 1 cm to 15 cm, preferably 2 to 10 cm. Moreover, essentially radially running shear
ribs extending from a radially outer area of the lower circumferential surface can be
provided. In this connection, a height of the shear ribs increases advantageously towards an
outer circumferential boundary of the stirring body. The previously stated features further
contribute to the making of a bubble-size distribution and a low average bubble diameter.
The average bubble diameter can, for example, be in the range from 1 mm to 10 mm,
preferably 2 mm to 8 mm.
In a further advantageous feature, the covering element has a rotationally symmetrical
shape. It can be a disk or a cone with its tip protruding into the recess or a hyperboloidtype
body. A further outer circumferential boundary of the covering element can be
toothed or also can have slits running radially towards the inside. In case of the
embodiment of the covering element as a cone protruding into the recess or as a
hyperboloid-like body, the volume of air in the recess can be small and an undesired
buoyancy of the stirring body caused by this can be minimized. The suggested structures
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on the further circumferential boundary of the covering element permit a particularly
uniform air outlet throughout the entire circumferential boundary of the stirring body. A
dispersion with a particularly homogeneous bubble size distribution can be generated with
this throughout the entire circumference of the stirring body.
In a first alternative embodiment, the covering element is firmly attached relative to the
stirring body to a frame carrying the shaft or to a bottom of a basin. If the covering element
is provided on a frame carrying the shaft, the stirring device can be designed completely as
a mounting unit. In this connection, a motor to drive the shaft suspended thereon is
provided on a tip of the frame which is usually designed like a tower and surrounds the
stirring body. A height of the frame can be designed such that the motor is located either
above a surface level of the liquid medium to be agitated, or also under a surface level of
same. Reference is made to the disclosure of DE 42 18 027 A1 as well as the disclosure of
DE 198 26 098 C2 which is herewith incorporated.
To avoid an undesired precession movement of the shaft, it is useful to provide that the
shaft is led through the stirring body and is held on its one end in a safety bearing provided
in the covering element. In case of an embodiment of the covering element as a disk, the
shaft can also be led through the disk and be held in a safety bearing provided underneath.
In a second alternative embodiment, the covering element is firmly connected via
connection means to the wall of the stirring body. In other words, in this case, the stirring
body and the covering element form one unit. In this connection, the connection means can
comprise essentially radially running bars extending from the inner side of the wall to an
upper side of the covering element facing the recess. Such bars advantageously only extend
over an outer radial section of the covering element. With the suggested second alternative
embodiment, the covering element can be advantageously held rotatably in a safety bearing
surrounding the air supply line.
With a version of the second alternative embodiment, the covering element is designed as a
hyperboloid-like further stirring body which is connected to the stirring body in such a way
that its further tip points away from the recess of the hyperboloid-like stirring body. In
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other words, the hyperboloid-like stirring body and the hyperboloid-like further stirring
body are arranged mirror-symmetrically in relation to a rotational plane running vertically
through the shaft. The suggested embodiment has the advantage that the covering element
designed in the form of a hyperboloid-like further stirring body develops a current directed
towards the further stirring body in the area of the bottom which current curves around this
and is radially directed to the outside on its circumferential boundary. Undesired deposits
in the area of the bottom of the basin are avoided by the formation of such a current.
With the first stirring device shown in Fig. 1, a stirring body (2) is attached to a shaft (1).
A wall (3) of the stirring body (2) has a hyperboloid-like shape. An air supply line (5) runs
in the vicinity of a bottom (4) of a (not shown here) basin to supply air into a funnel-like
recess (6) on an underside of the stirring body (2) opposite the bottom (4). An opening of
the recess (6) facing the bottom (4) is covered with a disk (7). A vertically running section
(8) of the air supply line (5) is led through a center of the disk (7). The disk (7) can be
attached firmly or also rotatably to the vertically running section (8). Naturally, it is also
possible that the disk is attached firmly on the bottom (4) via suitable support elements. In
this embodiment, the disk (7) is either permanently or also freely rotatably supported
relative to the stirring body (2). The suggested rotatability of the disk (7) helps to diminish
a current resistance to a rotating current created by the stirring body (2).
An annular gap (10) is formed between a lower circumferential surface (9) of the stirring
body (2) and a first circumferential boundary of the disk (7). Essentially radially running
first shear ribs (11) are provided in a radial section of the lower circumferential surface (9)
located further outside. A height of the shear ribs (11) preferably increases in a direction
pointing radially to the outside.
The air supplied through the air supply line (5) is now forced through the annular gap (10)
through the covering of the recess (6) via the disk (7). The escaping air is then distributed
in the form of fine air bubbles in the surrounding liquid medium by the rotating stirring
body (2), in particular the shear ribs (11) provided on the lower circumferential boundary
(9).
7
With the second stirring device (2) shown in Figs. 2a and 2b, the disk (7) is firmly
connected to an inner side of the wall (3) via connection bars (12) essentially extending in
a radial direction. The disk (7) is in turn designed and/or arranged relative to a lower
circumferential surface (9) of the stirring body (2) so that an annular gap (10) remains free.
The vertical section (8) of the air supply line (5) is led through the center of the disk (7). A
safety bearing (13) surrounding the vertical section (8) connects the disk (7) with the
vertical section (8).
Also with the second device shown in Figs. 2a and 2b, the air supplied into the recess (6)
via the air supply line (5) essentially exits via the annular gap (10) in the vicinity of the
lower circumferential surface (9) and is distributed finely into the surrounding liquid
medium, in particular, due to the effect of the rotating shear ribs (11).
In the exemplary embodiments shown, each recess (6) is covered with a disk (7). Instead of
the disk (7), however, another differently designed means of covering can also be used. For
example, it is possible to use cone-like or also hyperboloid-like formed covering means
instead of the disk (7) so that only a gap for supplying the air to the annular gap (10)
remains between an inner side of the wall (3) and the covering means. This can be used to
minimize the buoyancy generated in the recess (6) by supplying the air.
Fig. 3 shows a schematic cross sectional view of a third stirring device. The third stirring
device is designed similarly to the first stirring device. In this connection, however, the
disk (7) is part of a base (14) - also disk-shaped - supported on the bottom (4). The air
supply line (5) and the vertical section (8) of the air supply line (5) are affixed to the base
(14) which is preferably made of concrete. A section of the shaft (1) which passes through
the stirring body (2) is held rotatably in the safety bearing (13) surrounding the vertical
section (8). In this case, the safety bearing (13) is usefully held in the base (14). The
section of the shaft (1) passing through the stirring body (2) has ventilation openings (15)
through which the air supplied into the recess (6) by the air supply line (5) is introduced.
For this purpose, the section passing through the shaft (1) is provided with a separating
wall (16).
8
The embodiment suggested here of the fixation of the air supply line (5) of the vertical
section (8) as well as of the safety bearing (13) surrounding the vertical section (8) can
naturally also be applied for the second stirring device. In order to keep a flow resistance
as low as possible in this case, however, a sufficient distance must be provided between an
underside of the disk (7) and an upper side of the base (14) facing the stirring body (2).
Fig. 4 shows a fourth stirring device which is designed similarly to the third stirring device.
Here, a further base (17) which can be made of concrete, for example, is designed in the
form of a truncated cone whose tip protrudes into the recess (6). The safety bearing is
provided in the area of the tip. Transport ribs (20) are attached to an outer side of the wall
(3) pointing away from the recess (6), the height of whose ribs can increase in the direction
of a circumferential boundary of the stirring body (2). The transport ribs (20) can also be
curved in a top view (not shown here). Such transport ribs can naturally be used for the
previously described embodiments.
Fig. 5 shows a schematic cross sectional view of a fifth stirring device. Here, the covering
element is designed in the form of a hyperboloid-like further stirring body (18) whose
shape corresponds to the stirring body (2). The further stirring body (18) is firmly
connected to the stirring body (2) via connection bars (12). A further tip of the further
stirring body (18) is pointing away from the recess (6). In other words, the stirring body
and the further stirring body are essentially arranged mirror-inverted in relation to a
rotational plane. The safety bearing (13) is arranged in the area of the further tip of the
further stirring body (18). Reference sign (19) designates further shear ribs which are
provided on an outer side of the further stirring body (18) pointing away from the recess
(6) in a radially outer section. The arrows S1, S2 suggest the direction of currents being
created in the case of a rotation of the stirring bodies. By providing a covering configured
in the form of a hyperboloid-like further stirring body (18), a lower flow S1 is generated in
the vicinity of the bottom (4) which curves around in the area of the further stirring body
(18) and points in a radially outer direction. In similar fashion an upper flow S2 curves
around the stirring body (2) and also points in a direction pointing radially of the stirring
body (2). - With the suggested embodiment, it is possible, on the one hand, to generate
particularly fine air bubbles in the medium to be agitated and, on the other hand, to radially
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transport these in the medium particular far away from the stirring body. Finally, an
undesirable deposit of sediment on the bottom (4) of the basin can be avoided by the lower
flow S1 being created.
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List of reference signs
1 Shaft
2 Stirring body
3 Wall
4 Bottom
5 Air supply line
6 Recess
7 Disk
8 Vertical section
9 Lower circumferential surface
10 Annular gap
11 Shear rib
12 Connection bar
13 Safety bearing
14 Base
15 Air supply line
16 Separating wall
17 Further base
18 Further stirring body
19 Further shear rib
20 Transport rib
11
We Claim
1. A stirring device for activated sludges contained in a basin comprising a stirring
body (2) having a hyperboloid-like the stirring device shaped wall (3) attached to a
shaft (1) and an air supply line (5, 8) running along the bottom (4) of the basin to
supply air, wherein a vertical section (8) of the air supply line points to a funnellike
recess
(6) formed on an underside of the stirring body (2) characterized in that
an opening of the recess (6) formed on the underside is covered with a covering
element (7) in such a way that an annular gap (10) with a specified width remains
free between a lower circumferential surface (9) of the stirring body (2) and the
covering element (7), and that the vertical section (8) of the air supply line (8) is led
coaxially through the covering element (7) in relation to the shaft (1).
2. The stirring device as claimed in claim 1, wherein the annular gap (10) has a width
in the range of from 1 cm to 15 cm, preferably from 2 cm to 10 cm.
3. The stirring device as claimed in one of the preceding claims, wherein radially
running shear ribs (11) extending from a radially outer area of the lower outside
circumferential surface (9) are provided.
4. The stirring device as claimed in one of the preceding claims, wherein a height of
the shear ribs (11) increases towards an outer circumferential boundary of the
stirring body (2).
5. The stirring device as claimed in one of the preceding claims, wherein the covering
element has a rotationally symmetrical shape.
6. The stirring device as claimed in one of the preceding claims, wherein the covering
element is a disk (7) or a cone with its tip protruding into the recess (6) or a
hyperboloid-like body.
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7. The stirring device as claimed in one of the preceding claims, wherein the covering
element is firmly attached relative to the stirring body (2) to a frame carrying the
shaft (1) or to a bottom (4) of a basin.
8. The stirring device as claimed in one of the claims 1 to 6, wherein the covering
element is firmly connected via connection means to the wall (3) of the stirring
body (2).
9. The stirring device as claimed in claim 8, wherein the connection means comprise
essentially radially running bars (12) extending from the inner side of the wall (3)
to an upper side of the covering element facing the recess (6).
10. The stirring device as claimed in one of the claims 8 or 9, wherein the covering
element is a hyperboloid-like further stirring body (18) which is connected to the
stirring body (2) in such a way that its further tip is pointing away from the recess
(6) of the stirring body (2).
11. The stirring device as claimed in claim 10, wherein further shear ribs (19) are
provided on a radially outer section of an outer side of the further stirring body
(18).
12. The stirring device as defined in one of the preceding claims, wherein the shaft (1)
is led through the stirring body (2) and is held on its one end in a safety bearing
(13) provided in the covering element.
13. The stirring device as claimed in one of the preceding claims, wherein the covering
element is held rotatably in a safety bearing (13) surrounding the air supply line.
Dated this 20th day of January, 2010
Signature:
Name: DURGESH MUKHARYA
To: K&S Partners
The Controller of Patent Agent for the Applicant
The Patent Office, at Chennai

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=UjfAV5RUzdUTGWqSJkssJg==&loc=egcICQiyoj82NGgGrC5ChA==


Patent Number 280025
Indian Patent Application Number 398/CHENP/2010
PG Journal Number 06/2017
Publication Date 10-Feb-2017
Grant Date 07-Feb-2017
Date of Filing 20-Jan-2010
Name of Patentee INVENT UMWELT-UND VERFAHRENSTECHNIK AG
Applicant Address Am Pestalozziring 21 91058 Erlangen Germany
Inventors:
# Inventor's Name Inventor's Address
1 MARCUS HÖFKEN PLATEUSTRASSE 22A,91504 ERLANGEN
PCT International Classification Number B01F 7/00 ; B01F 3/04
PCT International Application Number PCT/EP2008/004915
PCT International Filing date 2008-06-19
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10 2007 037 584.2 2007-08-09 Germany