TECHNICAL FIELD

The present invention concerns an apparatus for scraping, transport and collection of slurry, comprising primarily a scraping and transport element to be arranged in a simple and rational way in a sedimentation basin in water treatment plants, said plants comprising sedimentation basins with slurry collection troughs and/or slurry processing plants.

BACKGROUND OF THE INVENTION

In certain sedimentation basins, particularly in Eastern Europe, and where large amounts of slurry are found, sedimentation basins comprise slurry troughs at each end of the sedimentation basin. Such sedimentation basins have been provided with transversally- controlled scrapers with the above-mentioned disadvantages.

The use of cable-drawn scrapers or scraping apparatus has also been suggested, in which one or more cables pull a wagon or sledge which holds the scraper at or near the bottom of the basin in a repeating to-and-fro motion. (SE-B-423 968; US-A-2 866 557; US-A-2 768 749; US-A-4 090 966; GB-A-1 504 518). The technology is an improvement over the state of the art concerning chain-driven scrapers, in that it has a significantly simpler, lighter and cheaper construction. Meanwhile, the system means that different equipment must be used to turn the scraper blade and control its rotation from a vertical to a horizontal position and vice versa under the reciprocating movement caused by the cables. The scraper blade, which comprises a metal blade which is arranged with its edge in the transport direction and most often is provided with a rubber edging strip, extends across the width of the basin, at right angles to the direction of transport. Under the reciprocating movement of the scraper blade, the slurry is stirred up, however, to give so-called sludge escape, due to turbulence building up behind the blade and maximum efficiency cannot therefore be reached. The loads on the apparatus also mean that it must be made of metal, and to prevent corrosion from eating away the apparatus too quickly, it must be manufactured in a more acid-resistant material, which increases costs. An apparatus in a sedimentation basin and the like for displacement of slurry and sediment collected on the bottom of the basin is known from SE-C-454,140, in which transport means is arranged to be moved back and forth near the bottom of the basin, whereby slurry and sediment is displaced by the reciprocating movement to one end of the basin, whereby the transporter consists of a mat comprising means with a wedge- shaped triangular cross-section, said means being arranged substantially perpendicular to the direction of travel of the transporter, and the point of the wedge is arranged in the return direction while the base of the wedge is arranged in the forward direction.

A transport element of a reciprocating scraper is also known from EP-B-O 532 484 for moving slurry in sedimentation basins and the similar objects in water purification plants, said element having a cross-section which has a downwardly-facing surface, a substantially curved convex surface and a substantially vertical concave surface, said concave surface being arranged in the forward, transporting direction.

All transport of slurry takes place with these elements placed in a perpendicular relationship to the longitudinal direction of the transporter, either a chain, net or rod move over the bottom of the sedimentation basin, whereby the chain moves continuously in one direction, and the net and rod move back and forth.

Previous transport elements have, however, proved to require a lot of material and transport space before mounting in the sedimentation basin. There is therefore a need for a new construction which meets the requirements of effective slurry transport at the same time as it meets the requirements of reduced transport and storage space in production, as well as simplified mounting in the sedimentation basin.

SUMMARY OF THE INVENTION

It is an aim of the present invention to provide an apparatus which meets these requirements. This is possible using a construction which allows a simple combination of a plurality of elements to reduce space, at the same time as providing a rational mounting arrangement. DETAILED DESCRIPTION OF THE INVENTION

It has now surprisingly been found possible to meet these requirements and solve these problems by means of the present invention, which is characterized in that the transporting element in cross-section has a lower horizontal flange, a transport surface arranged at an angle to the horizontal plane and an upper horizontal flange.

In another aspect of the invention, it comprises a mounting member comprising a U- shaped member which comprises two recesses arranged to receive it in the upper flange of the transport element.

In a more preferred embodiment, the U-shaped member is arranged to receive a driving rod overlying the transporting element.

The shape of the transporting element means that - after mounting in it a slurry basin - it will have an open triangular, or wedge-shaped cross-section in the transport direction.

The invention will now be described in more detail in the following, with reference to the appended drawings, in which:

FIG. 1 shows a cross-sectional view of a transporting element according to the invention, with mounting arrangement and towing rod;

FIG. 2 shows the embodiment of FIG.1 in perspective view at an angle from the rear FIG. 3 shows the embodiment of FIG.1 in perspective view at an angle from the front

Reference 1 in FIG.1-3 relates generally to a transporting element for a slurry basin, said element comprising a lower horizontal flange 2, an angled transport surface 3 and an upper horizontal flange 4. The angled transport surface 3 is shown here angled in relation to a supposed horizontal plane. The transporting element 1 is suitable manufactured in a quality steel, such as preferably stainless steel or acid-resistant steel. As can be seen in the cross-sectional figures, the transporting element is in one piece, and non-mounted transport elements can easily be stacked after being profiled but before mounting, to minimise the space taken up. The profile is also symmetrical, which means that there is no predetermined upper or lower side. The lower horizontal flange 2, angled transport surface 3 and upper horizontal flange 4 of the transporting element 1 are contiguous, as shown, and comprise various regions of a single material. Preferably, the material of the transporting element is the same in the lower horizontal flange 2, angled transport surface 3 and upper horizontal flange 4; i.e., the transporting element 1 is manufactured from a single material sheet (e.g. steel) which is bent at suitable locations and suitable angles to provide the illustrated transporting element 1. Upper 4 and lower 2 horizontal flanges should not overlap in the vertical direction; i.e. the upper horizontal flange 4 is a continuation of the angled transport surface 5 in a direction away from the lower horizontal flange 2. As the upper flange 4 and lower flange 2 are horizontal, the angle made between each of these flanges and the angled transport surface 5 is the same.

FIG. 1 also shows a mounting member 5 according to the invention. The mounting member 5 is comprised of a U-shaped loop, suitably made of steel-quality iron, such as stainless steel or acid-resistant steel. The mounting member has an extension in all dimensions. The U-shaped mounting member hereby comprises a bottom portion 6 and two side portions 7. On the edges of the side portions 7, in the upper part of the U- shaped mounting member are two recesses 8, which have dimensions such that the upper flange 4 of the transporting element 1 can be fitted in these double recesses (FIG.1). The U-shaped mounting member 5 also has a width such that it can receive a pulling rod 9 between the side portions 7 of the U-shape. The function of the pulling rod 9 will be explained below.

In FIG. 2-3, a mounting member 5 is shown being joined e.g. via welding, to a metal sheet 21 , a transporting element 1 being mounted to said mounting member 5 in the recesses 8. The flange 4 has thereby also been welded to the sides 7 in the region of the recesses 8. the transporting element's other lower flange 2 is welded to the metal sheet 21 in the same manner. A number of parallel steel plates 21 are located in a slurry basin, to which a number (depending on slurry quality and amount) of transporting elements 1 are mounted. The steel plate 21 runs on sliding rails of plastic (not shown) in the bottom of the basin. These plastic rails are put in place to minimize the friction between the steel plate 21 and the bottom of the basin. A pulling rod 9 is arranged and welded firmly to in the axis of symmetry of the basin, and across all transporting elements. The pulling rod 9 is coupled to a motor (not shown) and a rotating mechanism (not shown) to produce a to- and-fro motion for the entire transport assembly.

The displacement of the scraper unit can be achieved by means of hydraulic or electrically-powered units. The transport elements are thereby driven via a centrally- arranged rod via a vertical rod system which is driven up and down and then drives the horizontal rod which supports the transport elements via an angled rod.

By means of the present invention, overflow is minimized, as the slurry will primarily run along the transporting elements and be concentrated in the middle of the point of the V- shape between the transporting elements 1 and the bottom of the basin.

Furthermore, minimal turbulence is created around the scraper element and the to-and-fro movement of the scraper can thereby be used for transport of the slurry present in the sedimentation basin, providing significant energy efficiency. Upon the return stroke, water will flow over the upper surface and sink behind the transport element and thereby limit sludge escape. In an apparatus containing the present transport element, a length can be achieved which can be closely suited to the form and length of the basin in question. Furthermore, the stroke length for forward and rearward motion be adjusted within a wide range, but it can preferably be made very short, which means that simple hydraulic or pneumatic technology can be used.

The design according to the present invention creates a concentration of the slurry, whereby the tendency to overflow the transport element is substantially eliminated or is at least reduced by a great extent.

A slurry trough can be arranged at each end of a slurry basin. The slurry troughs can be replaced by a suction apparatus, or be complemented by a suction apparatus arranged to remove the slurry that is transported to and gathered at each end of the basin via suction.

It is clear to the skilled person that the scope of the present invention comprises a number of variations on the form of the transport element, all of which are covered by the appended claims. It is clear that the specific angles of the bending or the arc diameter to be chosen can be simply determined cased on the type of slurry involved.