WO2003045526A1

WO2003045526A1 - Apparatus for removal of surface scum

Info

Publication number: WO2003045526A1
Application number: PCT/FI2002/000847
Authority: WO
Inventors: Pekka Tuomikoski
Original assignee: Finnketju Invest Oy
Current assignee: Finnketju Invest Oy
Priority date: 2001-11-28
Filing date: 2002-11-01
Publication date: 2003-06-05
Anticipated expiration: 2004-05-28
Also published as: FI20012323A0; AU2002344539A1

Abstract

The invention relates to an apparatus for the removal of surface scum, especially in connection with a treatment space (T), such as a settling tank or the like, for a liquid to be processed, said apparatus comprising a scraper assembly (1) for conveying the scum present on the surface of the treatment space (T) by scraping the same mechanically to a discharge system (2). The apparatus comprises a scraper assembly (1; 1') movable back and forth (pl, p2) in the treatment space (T) on the one hand substantially level with a liquid surface (N) and on the other hand in a crosswise direction (p) relative to a lengthwise direction (s) of the treatment space (T), one or more scrapers (1'a) included therein being adapted in each opposite traveling direction (pl, p2) of the scraper assembly to convey surface scum essentially in the same direction for delivering the same to the discharge system (2).

Description

Apparatus for removal of surface scum

The invention relates to an apparatus for the removal of surface scum or supernatant sludge, especially in connection with a treatment space, such as a settling tank or the like, for a liquid to be processed, said apparatus comprising a scraper assembly for conveying the scum present on the surface of the treatment space by scraping the same mechanically to a discharge system.

First of all, particularly with regard to so-called settling tanks or clarification basins, it is prior knowledge to employ a scraper bar assembly, comprising a number of longitudinally successive scraper bars, which are operated by means of conveyor chains generally driven by way of a drive wheel and sheave assembly, the scraper bars being generally mounted releasably in connection therewith, e.g. by means of a screw joint or the like. This type of traditional technology is illustrated in fig. 10, according to which the scraper bars are generally adapted to operate in such a way that said bars are driven by chains present along the sides of a tank or basin such that, regarding the bottom, said bars are adapted to scrape bottom material into a sludge pocket and respectively to convey surface material to a collecting trough, i.e. a so-called gulp chute, extending across the tank. The collecting trough or chute is operated with a timer, such that a discharge gate included therein tips periodically to such a position that the sludge or scum present therein is allowed to migrate inside the same. The discussed arrangement has an objective to make sure that as little liquid as possible would discharge along with the surface scum or sludge. The above types of equipment are often hampered in practice by operating problems resulting from.the very collecting trough described above. Such problems are due to the fact that the highly passive operating principle of a collecting trough does not always function with- a sufficient reliability, since certain conditions allow the surface of a liquid tank to accumulate matter which has to be removed manually. Especially, in case of careless sustenance of the above-discussed processing, the accumulation of surface scum causes most diverse problems, which in the worst scenario lead to a disruption in the operation of the actual scraper bar assembly.

Attempts have been made to overcome the above problems by performing the removal of surface sum with enhanced activity. This has involved e.g. the use of a scraper bar assembly basically similar to the above-described type of scraper bar assembly, which is positioned above the liquid surface in connection with a collecting trough. A downside in this type of solution is firstly the complexity of its construction, which naturally leads to high investment, service, and maintenance costs. In addition, since the scraper assembly is positioned basically in its entirety above the liquid surface, it is particularly climatic conditions that result in occasionally inconvenient problems of freezing/ thermal expansion, and the like. The poor technical performance of a scraper assembly as described above is also largely due to- the fact that the scrapers of this particular scraper assembly are only putting in a working performance whenever progressing along the bottom run, while .being totally useless upon winding themselves onto the top run. Hence, top surface scrapers of the type described above and operating in the lengthwise direction of a liquid tank, basically the same way as the scraper assembly described in the introduction, have not been able to provide a sufficiently reliable and economically viable solution for overcoming the above- mentioned problems.

The object set for an apparatus . of the present invention is to provide a decisive improvement over the above-described problems and hence to raise essentially the available state of the art. In order to achieve this objective, the inventive apparatus is primarily characterized in that it comprises a scraper assembly movable back and forth in the treatment space on the one hand substantially level with a liquid surface and on the other hand in a crosswise direction relative to a lengthwise direction of . the treatment space, one or more scrapers included therein being adapted in each opposite traveling direction of the scraper assembly to convey surface scum essentially in the same direction for delivering the same to a discharge system.

It should be appreciated that the most significant advantages gained by an apparatus of the invention include its simplicity in construction and operation, as well as its reliability in operation. The benefits afforded by the invention are essentially based on a scraper assembly movable in a crosswise direction relative to a liquid tank and level with the liquid surface, by virtue of which the scrapers included therein can be made significantly shorter than those used in assemblies covering the full width of a liquid tank, in which case the scrapers must be constructed to be sufficiently massive, e.g. to prevent the same from bending. One major benefit gained by an ^'apparatus of the invention is also the fact that the . moving parts and mechanisms included therein are mostly located constantly below the liquid_. surface so as to minimize operating problems caused e.g. by freezing. In a preferred embodiment of the invention, the scraper assembly is adapted to scrape surface scum towards a discharge system longitudinally of the treatment space in two or more successive locations by means of scrapers movable by the action of a drive means. In this embodiment, the drive means are still provided by a preferably endless chain, the scrapers being mounted thereon in pivotable fashion in view of maintaining the scraping direction essentially the same in the reversing directions of a scraper assembly. The above type action, e.g. a so-called two- phase surface scum treatment, enables the removal of surface scum in a treatment ^• space in a highly laminar manner without significant turbulence, whereby the process occurring in a liquid volume is not otherwise disturbed for this' reason. It is further possible to implement the scraper assembly in such a way that the scrapers included therein' , are designed to be mechanically, such as- by the action of external force, pivotable for operating positions substantially different from each other relative to the drive means, this being accomplished without complicated mechanisms or assisting external force. In the above type of solution, for example, it is further preferred that the discharge gate be provided with a paddle wheel or impeller functioning under a force action transmitted e.g. ^' from the movement of a drive chain, which contributes to resisting the accumulation and migration of surface scum in undesired locations by directing the same effectively from the vicinity" into the interior of a discharge gate.

Preferred embodiments of the inventive apparatus are disclosed in the non-independent claims directed thereto.

The invention will be described in detail in the following specification - with reference^" to the accompanying drawings, in which fig. l shows an apparatus of the invention in one preferred embodiment in a plan view,

fig.^' 2 shows a section along a line Fig. 2 -Fig. 2 in fig.

1,

fig. 3 shows a section along a line Fig. 3 -Fig. 3 in fig.

1,

fig. 4 shows a section along a line Fig. 4-Fig. 4 in fig. 1,

fig; 5 shows a section along a line Fig. 5-Fig. 5 in fig.

1,

fig. 6 shows one preferred lock mechanism in connection with a discharge gate,

fig. 7 shows a section along a line Fig. 7 -Fig. 7 in fig. 1,

fig. 8 shows the detail Fig. 8 in fig. 2,

figs. 9a-9c show in a plan view, a front view, arid an end view, respectively, the movement of scrapers in a' type of solution described above' as a result of a mating surface arrangement, and f ig . 10 shows a settling tank equipped with a traditional scraper bar assembly and a collecting trough.

The invention relates to an apparatus for the removal of surface scum or supernatant sludge, especially in connection with a treatment space T for a liquid to be processed, such as a settling tank or the like, said apparatus comprising a scraper assembly 1 for conveying the scum present on the surface of the treatment space T by scraping the same mechanically to a discharge system- 2. . The apparatus comprises a scraper assembly 1; 1' movable back and forth pi, p2 in the treatment space T, particularly on the_. principle depicted in fig. 1 and further according to e^". g. figs. 2-5, on the one hand substantially level with a liquid surface N and, on the other hand, in a crosswise direction p- relative to a, lengthwise direction s of the treatment space T, one or more scrapers l'a included therein being adapted in each opposite traveling direction pi, p2 of the scraper assembly to convey surface scum essentially in the same direction for ^' delivering the same to the discharge system 2.

In a particularly preferred embodiment, ^'.as shown especially in a plan view of fig. 1 and in side views of figs. 3 and 4, the discharge system 2 is constituted by a discharge gate 2a, formed in a wall se confining a liquid present in the treatment space T and set essentially level with a liquid surface T, which is provided, e.g. on the principle depicted in fig. 6, with a lock mechanism 2al . for regulating arid/or discontinuing a flow through the discharge gate as the action of -the scraper assembly 1; 1' is on hold. In a further preferred embodiment, especially in reference to the operating principle of the embodiment shown in fig. 1, the scraper assembly 1; 1' is adapted to -scrape surface scum towards the discharge system 2 ; 2a in the lengthwise direction s of the treatment space T at two xl , x2 successive points by means of the scrapers l'a movable under the action of a drive means. In a preferred embodiment, depicted particularly in the drawings, the scraper' assembly 1; 1' comprises an endless drive means l'b, such as a chain, a belt or the like, adapted to be movable by drive wheels or sheaves 3, the scrapers l'a being pivotably mounted thereon, as shown e.g. in fig. 8, for maintaining the scraping direction thereof as desired in the reversible traveling directions pi, p2 of the scraper assembly 1; 1' .

Hence, as shown especially in fig. 1, the scraper assembly 1; 1' preferably includes a number ^' of scrapers l'a successively in its traveling direction p .for discharging surface scum in the scraper assembly's first traveling direction pi towards those scrapers l'a which are moving in the scraper assembly's 1; 1' second traveling direction p2. Respectively, the scrapers l'a, which are moving in the- scraper assembly's 1; 1' second traveling direction p2 , are adapted to scrape surface scum, in conjunction with the wall Se confining a liquid present in the treatment space T, towards an intake port 2a included in the discharge system 2.

Consequently, in a preferred embodiment, a scraper l'a included in the scraper assembly 1; 1' is designed to pivot to operating positions yl, y2 substantially different from each other relative to the drive means by way of a mechanical drive system 5, such as on the principle depicted especially in figs. 9a-9c, under the action of external force. Thus, particularly in reference to the preferred embodiment shown in figs. 8 and 9c, a scraper l'a included in the scraper assembly 1; 1' is linked to a drive means l'b, which effects its movement, by way of a spring-loaded 4a retainer system 4, which enables a stable clamping of the scraper la as a result of external force, such as by steering a guide. rod ot, movable together with the scraper bar l'b, under the action of a mating surface arrangement 5a included in the drive system 5, to the desired end positions yl , y2 against an arcuate guide surface 4b included therein. The same principle applies also at the opposite end of. the scraper assembly.

As shown particularly in fig. 9a, the scraper l'a, presently in the first operating position yl , collides first with an upper rod 5al, as a result of which the scraper l'a pivots first to a substantially horizontal position according to fig. 9a, in which the upper rod 5al is able to pass through a recess ul present at the top edge of the scraper. Then, the scraper collides further with a lower rod 5a2, as a result of which the scraper pivots to its second operating position y2 as said rod is ultimately able to pass through a second recess u2 present at the bottom edge of the scraper.

In a preferred embodiment of the invention, referring especially to figs. 1 and 4, the discharge system 2 comprises at least one additional scraper 2b, such as an impeller or ^• the like, rotatable about a substantially vertical axis z, which, as a result of its rotating motion w, delivers surface scum into an intake duct 2a included in the . discharge system 2. In a further preferred embodiment, this additional scraper 2b is adapted to rotate w together with the scraper assembly 1; 1', such as through the action of a drive chain 2bl, a_. drive belt or the like, connected to the drive wheel 3. Figs. 2 and 3 illustrate drive wheel and sheave systems 3, along with support frames TR therefor, present at the opposite ends of a scraper^' assembly, whereby fig. 3, in particular, shows an electric motor S , along with its gear system, for operating the scraper assembly 1; 1'. Furthermore, fig. 3 shows e.g. a gate valve 2al, along with its actuator TM, associated with the discharge gate 2a, as shown e.g. in fig. 6, whose operation is based on having the discharge gate 2a closed whenever the scraper assembly is in an inactive condition and having it opened every time the scraper assembly is activated. Naturally, it is also possible- to effect operation of the gate valve 2al by using purely mechanical drive elements. Fig. 7 illustrates a further preferred operating principle for the drive system 5, wherein a common frame R is provided, in addition to rods 5al, 5a2 present therein and included in the mating surface arrangement 5a, with guide elements 5b for making sure that the scrapers l'a are guided to travel in a proper position through this particular passage. According to fig. 1, this same construction is applicable at . either opposite end of the scraper assembly. Further, in accordance with fig. 1, and more specifically fig. 5, it is preferable to utilize, naturally depending on the dimensions of each particular treatment space T, one or more intermediate frames TR' for supporting the scraper assembly i; 1' over a section between the sheaves 3. The reference kpj , depicted in figs. .1-5 and 10, refers to a conventional scraper' bar ^"assembly used in a settling tank, or to a sub-assembly included therein.

It is obvious that the invention is not limited to the embodiments illustrated or described above, but a wide range of variations and modifications can be made therein _. within the scope of the basic inventive concept. Firstly, the invention can be applied with highly diversified types of tanks or reservoirs, and the components included in a scraper assembly can be manufactured from the most diversified of materials by using the most^' diversified of manufacturing processes. Secondly, it is possible to apply the most diversified of profiles as a chain profile for the drive means, although the type of chain profiles, developed by the Applicant and described e.g. in Finnish patents 64707, 85755, 91798, and 101098,- offer, especially in a plastic design, a multitude of various advantages, particularly when the attachment of scrapers is effected by a direct screw connection directly with the back portion of a shaped piece included in the chain. For example, when using a so-called bicycle chain type of chain, it will be necessary to employ an angle or the like element attached to the back of the^' chain, the mere attachment of scrapers producing moments in such element, and^' thus, in terms of its performance and operating reliability, it is not even close to the standard of the above-mentioned chains. Naturally, it is also obvious that an assembly of the invention can be used not only in the above type of settling tank application but also in the most diversified of other suitable processes.

Claims

Claims :

1. An apparatus for the removal of surface scum, especially in connection with a treatment space (T) , such as a settling tank or the like, for a liquid to be processed, said apparatus comprising a scraper assembly (1) for conveying the scum present on the surface -of the treatment space (T) by scraping the same mechanically to a discharge system (2) , characterized in that the apparatus comprises a scraper assembly (1; 1') movable back and forth (pi, p2) in the treatment space (T) on- the one hand substantially level with a liquid surface (N) and on the other hand in a crosswise direction (p) relative to a lengthwise direction (s) of the treatment space (T) , one or more scrapers (l'a) included therein being adapted in each opposite traveling direction (pi, p2) of the scraper assembly to convey surface scum essentially in the same direction for delivering the same to the discharge system (2) .

2. An apparatus as set forth in claim 1, characterized in that the discharge system (2) is constituted by a discharge gate. (2a) , formed in a wall (Se) confining a liquid present in the treatment space (T) and set - essentially level with a liquid surface (T) , which is provided with a lock mechanism (2al) , such as a gate valve or the like, for regulating and/or discontinuing a. flow through the discharge gate as the action of the scraper assembly (1; 1') is on hold.

3. ^• An apparatus as set forth in claim 1 or 2 , characterized in that the scraper assembly (1; 1') is adapted to scrape . surface scum towards the discharge system (2; 2a) in the lengthwise direction (s) of the treatment space (T) at two (χi, χ2) successive points by means of the scrapers (l'a) movable under the action of a drive means.

4. An apparatus as set forth in claim 3, characterized in that the. scraper assembly (1; 1') comprises an endless drive means (l'b) , such as a chain, a belt or the like, adapted to be movable by drive wheels or sheaves (3), the scrapers (l'a) being pivotably mounted thereon for maintaining the scraping direction thereof as desired in the reversible traveling directions (pi, p2) of the scraper assembly (1; 1') .

5. An apparatus as set forth in any of preceding claims 1-4, characterized in that- the scraper assembly (1; 1') comprises one- or more scrapers (l'a) successively in its traveling direction (p) for discharging surface scum in the scraper assembly's first traveling direction (pi) essentially towards one or more scrapers (l'a) which are moving in the scraper assembly's (1; 1') second traveling direction (p2) .

6. ^' An apparatus as set forth in claim 5, characterized in that the scraper assembly's (1; 1') one or more scrapers (l'a), which are moving in the second traveling direction (p2) , are adapted to scrape surface scum, in conjunction with the wall (Se) confining a liquid present in the treatment space (T) , towards an intake port (2a) included in the discharge system (2) .

. An apparatus as set forth in any of preceding claims 1-6, characterized in that a scraper (l'a) included in the scraper assembly (1; 1') is adapted to be pivotable to operating positions (yl, y2) substantially different from each other relative to the drive means (l'b) by way of a mechanical drive system (5) , such as under the action of external force.

8. An apparatus as set forth in claim 7, characterized in that a scraper (l'a) included in the scraper assembly (1; 1') is linked to the drive means (l'b) , which effects its movement, by way of a spring- loaded (4a) retainer system (4) , which enables a stable clamping of the scraper (la) as a result of external force, such as by the action of a mating surface arrangement (5a) included in the drive system

(5) , in the desired end positions (yl, y2) under the guidance of an arcuate guide surface (4b) included therein, or in a corresponding fashion.

9. An apparatus as set forth in any of preceding claims 1-6, characterized in that the discharge system (2) comprises one or more additional scrapers (2b) , such as an impeller or the like, rotatable about a substantially vertical axis (z) , which, as a result of their rotating motion (w) , deliver surface scum into an intake duct (2a) included in the discharge system (2) .

10. An apparatus as set forth in claim - 9, characterized in that the additional scraper (2b) is adapted to rotate (w) together with the scraper assembly (1; 1'), such as through the action of a drive chain (2bl) , a drive belt or the like,^' connected to the drive wheel (3) , or in a corresponding fashion.