WO2003095061A1

WO2003095061A1 - Apparatus for the removal of surface scum in a circular processing space

Info

Publication number: WO2003095061A1
Application number: PCT/FI2003/000295
Authority: WO
Inventors: Pekka Tuomikoski
Original assignee: Finnketju Invest Oy
Priority date: 2002-05-10
Filing date: 2003-04-15
Publication date: 2003-11-20
Also published as: AU2003226847A1; FI20020886A0; EP1503838A1

Abstract

The apparatus, which constitutes the object of the invention and is adapted for use in a circular processing space (1), such as in a settling tank or the like, comprises mechanical processing elements (2), first of all for passing sludge present on the bottom of the processing space (1) out of the processing space by means of one or more bottom rakes (2a) rotatable around a centre (x) of the processing space through a bottom outlet mechanism (3) present on the floor of the processing space and, on the other hand, for passing supernatant sludge accumulating on a liquid surface (np) present in the processing space, out of the processing space by means of one or more surface rakes (2b) rotatable (w) around the centre (x) of the processing space through a surface outlet mechanism (4). The surface rake (2b) rotating (w) in the processing space (1) is provided with mechanical actuating elements (5), comprising one or more actuators (5a and/or 5b), which is/are movable from a basic position (I) to an operative position (I', I') divergent from a longitudinal direction (s) of the surface rake's main frame (2b') and which is/are particularly adapted for enhancing the passage of floating scum to the surface outlet mechanism (4) or for enabling a passage of the surface rake (2b) past an obstacle (E) present in the processing space.

Description

APPARATUS FOR THE REMOVAL OF SURFACE SCUM IN A CIRCULAR PROCESSING SPACE

The invention relates to an apparatus in a circular processing space, such as in a settling tank or the like, said apparatus comprising mechanical processing elements, first of all for passing sludge present on the bottom of the processing space out of the processing space by means of one or more bottom rakes rotatable around a centre of the processing space through a bottom outlet mechanism present on the floor of the processing space and, on the other hand, for passing supernatant sludge accumulating on a liquid surface present in the processing space, out of the processing space by means of one or more surface rakes rotatable around the centre of the processing space through a surface outlet mechanism present substantially at the liquid level of the processing space.

Circular settling . tanks of the above type have been known and used for a long time provided with traditional technical solutions. Thus, first of all, the settling tank floor is usually banked down towards its centre, the outlet drain for settled sludge being located at the centre of the settling tank. On the other hand, the mechanical processing elements used in the above type of traditional settling tanks , are implemented e.g. in such a way that a settling tank is provided with an overhead drive bridge, adapted to be rotatable around the centre of- the settling tank by means power elements and having surface rakes coupled therewith. The surface rakes are connected, e.g. by way of rigid arms, to bottom rakes for operating the same in synchronization with the surface rakes. The above type traditional solutions involve a variety of problems, which are primarily due to the fact that the drive bridge above a liquid tank is always quite a massive and heavy structure, calling for unreasonably high operating power. Secondly, a practical problem often encountered today in the process of removing supernatant or floating sludge is that too much floating sludge or scum is allowed to build up on the settling tank surface, making it necessary to remove it manually at regular intervals in order to maintain the sedimentation process operational. On the other hand, the sweeping carried out by means of surface rakes used in available settling tanks proceeds, e.g. at an obstacle present in the settling tank, in such a way that the surface rake is provided e.g. with a flexible structure, which yields by deflection at the obstacle and returns to its straight condition thereafter. A drawback with this type of constructions is first of all wearing, as well as the additional fact that in adverse conditions the surface rakes ultimately assume the wrong shape permanently and, therefore, must be repaired or replaced from time to time.

An apparatus according to the present invention is intended to provide a decisive improvement regarding the above-discussed problems and hence to raise essentially the available prior art. In order to implement this object, an apparatus of the invention is principally characterized in that the surface rake rotating in the processing space is provided with mechanical actuating elements, comprising one or more actuators, which is/are movable from a basic position to an operative position divergent from a longitudinal direction of the surface rake's main frame and which is/are particularly adapted for enhancing the passage of floating scum to the surface outlet mechanism, for enabling a passage of the surface rake past an obstacle present in the processing space, and/or for the like purpose.

The most important benefits offered by an apparatus of the invention include the simplicity, reliability and efficiency of its construction, configuration and operation, which first of all enables the effective minimization of operating power for mechanical process equipment in a circular processing space, such as a settling tank, as well as the service and maintenance demand thereof . By virtue of the inventive mechanical actuators, the guidance of floating scum to a surface outlet mechanism is first of all remarkably enhanced by collecting the same upstream of the surface outlet mechanism sufficiently far away from the surface outlet mechanism in a radial direction. On the other hand, an ideal implementation of the inventive apparatus is conceivable, particularly by the application of a driving force transmitted from above in such a way that the required transmission of drive through the liquid surface does not cause problems regarding the operation of a surface rake as an obstacle avoiding device included therein enables continued rotation of the surface rake without, ny contact at all with the discussed obstacle. Thus, the advantage gained by mechanical actuating elements present in an apparatus of the invention lies particularly in the fact that the sludge or scum present in front of a surface rake is guided thereby, such that too much thereof cannot build up or accumulate on the liquid surface and, on the other hand, also such that it remains permanently upstream of the surface rake and cannot unintentionally migrate over to the downstream side thereof, e.g. due to an obstacle present in the settling tank.

Preferred embodiments for an apparatus of the invention are disclosed in the dependent claims directed thereto.

The invention will now be described in detail with reference to the accompanying drawings, in which

fig. 1 shows a circular processing space, such as a settling tank, making use of one preferred apparatus of the invention,

fig. 2 shows one preferred operating principle depicted in successive steps for mechanical actuating elements included in an apparatus of the invention and intended specifically for enhancing the guidance of floating scum to a surface outlet mechanism,

fig. 3 shows in a further preferred embodiment one preferred operating principle depicted, in successive steps for mechanical actuating elements included in an apparatus of the invention and intended specifically for enabling the passage of a surface rake past an obstacle present in a liquid tank, and shows an operating principle depicted in successive steps for another preferred embodiment of the inventive apparatus intended specifically for enhanced raking action in association with an outlet mechanism.

The invention relates to an apparatus in a circular processing space 1, such as in a settling tank or the like, said apparatus comprising mechanical processing elements 2, first of all for passing sludge present on the bottom of the processing space 1 out of the processing space by means of one or more bottom rakes 2a rotatable around a centre x of the processing space through a bottom outlet mechanism 3 present on the floor of the processing space and, on the other hand, for passing supernatant sludge accumulating on a liquid surface np present in the processing space, out of the processing space by means of one or more surface rakes 2b rotatable w around the centre x of the processing space through a surface outlet mechanism 4 present substantially at the liquid level np of the processing space. The surface rake 2b rotating w in the processing space 1 is provided with mechanical actuating elements 5, comprising one or more actuators 5a and/or 5b, which is/are movable from a basic position I to an operative position I', I" divergent from a longitudinal direction s of the surface rake's main frame 2b' and which is/are particularly adapted for enhancing the passage of floating scum to the surface outlet mechanism 4, for enabling a passage of the surface rake 2b past an obstacle E present in the processing space, and/or for the like purpose. In one preferred embodiment for an apparatus of the invention, particularly in reference to the operating principle depicted in successive steps in fig. 2, the actuator 5a for the surface rake 2b, which is specifically intended for enhancing the passage of floating or supernatant scum to the surface outlet mechanism 4, comprises an assembly pivotable kl relative to the surface rake ' s main frame 2b ' onto the upstream side thereof for gathering towards the surface outlet mechanism 4 the floating scum present upstream of the surface rake, at a further distance L from the surface outlet mechanism 4 in a radial direction . The discussed actuator 5a can be implemented, as shown e.g. in fig. 2, such that it comprises an assembly provided with a raised lip member Re, the lip being intended at this point to prevent floating scum present upstream of a surface rake from passing through the surface rake as the discussed assembly is in the process of pivoting to its operative position I'. In this context, it is naturally also conceivable to use e.g. a flat panel assembly or else a lip profile like the one shown in fig. 2, yet without a floor panel.

In the embodiment described in this context, the guiding actuator 5a of a surface rake is adapted to pivot kl in connection with the surface outlet mechanism 4 to the operative position I ' substantially perpendicular to the longitudinal direction s of the surface rake's main frame 2b' by means of a mechanical guidance system 6a, comprising a guide 6al fastened to the discussed actuator 5a and adapted to co-operate in response to a guide surface 6a2 provided in communication with the surface outlet mechanism 4 or in the like manner. In a further preferred embodiment for an apparatus of the invention, particularly in reference to the operating principle depicted in successive steps in fig. 3, the actuator 5b for the surface rake 2b, which is specifically intended for enabling a passage of the surface rake past the obstacle E, such as e.g. a transmission shaft VS shown in fig. 1, present in the processing space 1, comprises an assembly, which is pivotable k2 relative to the surface rake's main frame 2b' and adapted to pivot to its operative avoidance position I" directed upstream of the surface rake's main frame 2b' essentially ahead of the obstacle E for enabling a passage thereby.

In a further preferred embodiment in this context, the obstacle avoidance mechanism 5b of a surface rake is adapted to pivot in connection with said obstacle E by means of a mechanical action control system, comprising a guide bracket 6bl, which is attached to the discussed actuator 5b and adapted to co-operate in response to a guide 6b2 provided in communication with said obstacle E.

In yet another preferred embodiment, particularly in reference to what is shown in fig. 4, the surface rake 2b has its element 2bc, which rakes supernatant scum towards the surface outlet mechanism 4, adapted to be rotatable k3 relative to the longitudinal axis s of the surface rake 2b, particularly for raking supernatant scum in its inclined operative position I" along a guide surface assembly op present in communication with the surface outlet mechanism 4 substantially above the liquid level np, said solution particularly enabling a rotational motion w of the surface rake 2b to proceed in a substantially constant plane t. In this context, the discussed element 2bc is designed as a deflected member, having its distal end in a position substantially perpendicular to the guide wheel assembly op in the process of sliding therealong.

In a still further preferred embodiment for an apparatus of the invention, the mechanical actuating elements 5 provided on the surface rake 2b, such as the guidance actuator 5a and the obstacle avoidance mechanism 5b set behind it in the longitudinal direction s, and preferably also the surface rake's element 2bc raking supernatant scum to the surface outlet mechanism 4, are adapted to effect a return movement RM to their basic position I in a self- operated manner, which is implementable e.g. with adjustable spring-loaded arrangements sp or in the like manner.

According to the embodiment shown e.g. in fig. 1, the apparatus comprises preferably a plurality of bottom rakes 2a operating in communication with the floor of the processing space 1, which are fixedly connected by a first end thereof to a subframe A linked rotatably w to the processing space centre x and which are operated by means of a transmission system W, providing a driving connection to a second end thexeof

, and established by way of drive elements KK present substantially above the liquid level np, and by means of an endless transmission member 7, such as a chain, a cable or the like, operated by the action of a drive and/or idler wheel assembly 6 or the like moving in communication with a transmission shaft VS and the walls of the processing space 1. In this context, one or more surface rakes 2b, included in the apparatus, are adapted to be operated by means of mechanical transmission elements VE, such as one or more arms or the like, connected to the bottom rake 2a, as well as by the action of the subframe A present at the processing space centre x, the surface rake 2b being coupled therewith at one of its ends by means of a fastening mechanism FM precluding at least substantially its movement in the longitudinal direction s.

In still another preferred embodiment for an apparatus of the invention, one or more surface rakes 2b, included in the apparatus, are designed as an assembly floating on the liquid surface np of the processing space, whereby, in a further preferred embodiment, it is coupled with the transmission elements VE and/or the subframe- A .by means of a fastening mechanism enabling its movement in a vertical direction h. When using this type of embodiments, it is natural that the surface outlet mechanism must also be provided with a necessary freedom of action. A solution of the type referred to in this context, which is e.g. partially or totally buoyant, enables minimization of the dimensions of constructions included in the apparatus as the surface rakes are capable of neutralizing some of their own mass by virtue of their buoyancy.

It is obvious that the invention is not limited to the embodiments depicted or described above, but it can be subjected to variations within the basic inventive concept in accordance with given conditions and operating requirements. Thus, first of all, it is self-evident that small-sized processing spaces can be provided with just one surface and bottom rake. On the other hand, it is naturally possible to implement the maneuvering of mechanical actuating elements of the invention in most diversified manners and mechanisms, in which context e.g. mechanical guide systems of the above type make it possible to provide solutions which are optimally functional regarding service and maintenance and economically viable. Naturally, it is obvious that the apparatus can also be set to operate in such a way that the subframe present at the centre of a liquid tank is made movable, as a result of which the bottom rakes and/or surface rakes, being fixedly secured thereto, become movable as well. However, this requires an operating power for the apparatus which significantly exceeds that used in the embodiment depicted in the attached drawings-, in which the drive is effected by the action of a chain present along the periphery of a settling tank. In a preferred embodiment, the discussed chain is made of plastics, which contributes for its part to the optimally low service and maintenance demand.

Claims

1. An apparatus in a circular processing space

(1) , such as in a settling tank or the like, said apparatus comprising mechanical processing elements

(2) , first of all for passing sludge present on the bottom of the processing space (1) ut of the processing space by means of one or more bottom rakes

(2a) rotatable around a centre (x) of the processing space through a bottom outlet mechanism (3) present on the floor of the processing space and, on the other hand, for passing supernatant sludge accumulating on a liquid surface (np) present in the processing space, out of the processing space by means of one or more surface rakes (2b) rotatable (w) around the centre (x) of the processing space through a surface outlet mechanism (4) present substantially at the liquid level (np) of the processing space, characterized in that the surface rake (2b) rotating (w) in the processing space (1) is provided with mechanical actuating elements (5) , comprising one or more actuators (5a and/or 5b) , which is/are movable from a basic position (I) to an operative position (I', I") divergent from a longitudinal direction (s) of the surface rake's main frame (2b') and which is/are particularly adapted for enhancing the passage of floating scum to the surface outlet mechanism (4) or for enabling a passage of the surface rake (2b) past an obstacle (E) present in the processing space.

2'. An apparatus as set forth in claim 1, characterized in that the actuator (5a) for the ^• surface rake (2b) , for enhancing the passage of floating scum to the surface outlet mechanism (4) , comprises an assembly, pivotable (kl) relative to the surface rake's main frame (2b¹) onto the upstream side thereof, for gathering towards the surface outlet mechanism (4) the floating scum present upstream of the surface rake, at a further distance (L) from the surface outlet mechanism (4) in a radial direction (R) ■

3. An apparatus as set forth in claim 2 , characterized in that the guiding actuator (5a) of a surface rake for floating scum is adapted to pivot

(kl) in connection with the surface outlet mechanism

(4) to the operative position (I') substantially perpendicular to the longitudinal direction (s) of the surface -rake's main frame (2b') by means of a mechanical guidance system (6a) , comprising a guide (6al) fastened to the discussed actuator (5a) and adapted to co-operate in response to a guide surface (6a2) provided in communication with the surface outlet mechanism (4) or in the like manner.

4. An apparatus as set forth in any of preceding claims 1-3, characterized in that the actuator (5b) for the surface rake (2b) , for enabling its passage past the obstacle (E) present in the processing space (1) , comprises an assembly, which is pivotable (k2) relative to the surface rake's main frame (2b¹) and adapted to pivot to the operative avoidance position (I") directed upstream of the surface rake's main frame (2b') essentially ahead of the obstacle (E) for enabling a passage thereby.

5. An apparatus as set forth in claim 4, characterized in that the obstacle avoidance mechanism (5b) of a surface rake is adapted to pivot in connection with said obstacle (E) by means of a mechanical action control system, comprising a guide bracket (6bl) , which is attached to the discussed actuator (5b) and adapted to co-operate in response to a guide (6b2) provided in communication with said obstacle (E) .

6. An apparatus as set forth in any of preceding claims 1-5, characterized in that the surface rake

(2b) has its element (2bc) , which rakes supernatant scum towards the surface outlet mechanism (4) , adapted to be rotatable (k3) relative to the longitudinal axis

(s) of the surface rake (2b) , particularly for raking supernatant scum along a guide surface assembly (op) present in communication with the surface outlet mechanism (4) substantially above the liquid level (np) in a manner enabling the rotational motion (w) of the surface rake (2b) to proceed in a substantially constant plane (t) .

7. An apparatus as set forth in any of preceding claims 1-6, characterized in that the mechanical actuating elements (5) provided on the surface rake (2b) , such as the guidance actuator (5a) and the obstacle avoidance mechanism (5b) set behind it in the longitudinal direction (s) , and/or the surface rake's element (2bc) raking supernatant scum to the surface outlet mechanism (4) , are adapted to effect a return movement (RM) to their basic position (I) in a self- operated manner, such as by means of adjustable spring-loaded arrangements (sp) or in the like manner.

8. An apparatus as set forth in any of preceding claims 1-7, characterized in that the apparatus comprises a plurality of bottom rakes (2a) operating in communication with the floor of the processing space (1) , which are fixedly connected by a first end thereof to a subframe (A) linked rotatably (w) to the processing space centre (x) and which are operated by means of a transmission system (W) , providing a driving connection to a second end thereof and established by way of drive elements (KK) present substantially above the liquid level (np) , and by means of an endless transmission member (7) , such as a chain, a cable or the like, operated by the action of a drive and/or idler wheel assembly (6) or the like moving in communication with the walls of the processing space (1) .

9. An apparatus as set forth in claim 8, characterized in that one or more surface rakes (2b) , included in the apparatus, are adapted to be operated by means of mechanical transmission elements (VE) , such as one or more arms or the like, connected to the bottom rake (2a) ,- as well as by the action of the subframe (A) present at the processing space centre

(x) , the surface rake (2b) being coupled therewith at one of its ends by means of a fastening mechanism (FM) precluding at least substantially its movement in the longitudinal direction (s) .

10. An apparatus as set forth in any of preceding claims 1-9, characterized in that one or more surface rakes_, (2b) , included in the apparatus, are designed as an assembly floating on the liquid surface (np) , whereby it is coupled with the transmission elements (VE) and/or the subframe (A) by means of a fastening mechanism enabling its movement in a vertical direction (h) .