EP0532490B1

EP0532490B1 - Dredger for removing mud without stirring up sludge and/or other sediments

Info

Publication number: EP0532490B1
Application number: EP19920870146
Authority: EP
Inventors: Luc De Ryck
Original assignee: Dredging International NV
Current assignee: Dredging International NV
Priority date: 1991-09-11
Filing date: 1992-09-11
Publication date: 1997-03-12
Anticipated expiration: 2012-09-11
Also published as: DE69218083T2; EP0532490A1; BE1005307A5; DE69218083D1; ES2099244T3

Description

The invention relates to a dredger equiped with at least one funnel which is adjustable under an arbitrary angle which contains a scraper belt for digging up sludge and other light sediments.
In certain circumstances, when accumulations of sedimented sludge and other fine grained materials have to be removed from narrow waterways, canals and watercourses, for example in built-up areas without stirring up the sludge in the water, because this has to be avoided for example from an ecological point of view, very particular problems arise. As a consequence, use can therefore not be made of the conventional dredging techniques.
In the conventional dredging techniques, use is especially made of bucket dredgers which do not meet the stated object at all since the sludge is partially distributed in the water by stirring up and by turbulence during the vertical transport and the stated object can than not be reached at all. Suction dredgers are also not appropriate, partially for the same reasons and also because large amounts of water have to be displaced compared to the amount of dredged sludge. Separating the water and the sludge afterwards back from the so transported mixture is particularly difficult, in other words expensive and/or time consuming. The excess of water defiled with sludge and possibly with polluents contained therein cannot be discharged again in the watercourse if the surrounding water has to be kept as clean as possible and as less distrubed as possible under the hereabove sketched circumstances.
It has been proposed by DE patent 33455 to dig up earth amongst others under water, by making use, for the evacuation of the earth, of a transportation belt while the materials are excavated by mechanically actuated shovels. The materials are pushed along a plate until they reach the transportation belt the active side of which is running inside a funnel which can be installed under the desired angle.
When considering the problems briefly set forth above the use of shovels whether or not disposed close to a transportation belt must be disregarded as very light materials like silt and similar sedimentary materials, will for a great deal not reach the transportation belt but anyway give rise to a considerable stirring up of these materials into the surrounding water.
An object of the invention is therefore to design a dredger which provides a solution for the just sketched problems and which enables to remove the sludge and/or other sediments from watercourses without stirring this material up in the water and this, as already mentioned hereinabove, while adding a minimum amount of water during the vertical transport.
In order to realize this according to the invention, the scraper belt is extending up to the lowermost part of said funnel which lowermost part of the funnel ends in a scraper blade, so that sludge and other slight sediments can be transported along said funnel.
Other details and advantages of the invention will become apparent from the following description of a dredger according to the invention. This discription is only given by way of example and does not limit the invention. The reference numerals relate to the annexed figures.
Figure 1 is a schematical side elevation view of a dredger according to the invention.
Figure 2 is a schematical top plan view of the dredger according to the invention.
Figure 3 is, on a larger scale, a schematical longitudinal section of the ladder together with the funnel and the scrape belt moving therein.
Figure 4 is a section according to line IV-IV of figure 3.
Figure 5 is a section according to line V-V of figure 3.
Figure 6 relates to a detail of the invention.
Figure 7 relates to a variant of the embodiment according to figure 6.
Figure 8 is, on a still larger scale, a cross-section through three funnels near the drive means of the ladders of the dredger according to the invention.
The dredger shown in these figures consists of a pontoon 1 comprising a funnel-shaped dump space 2. The hold 3 is provided for mounting components which do not belong to the essence of the invention.
On the frontside or on the side which can be considered as the stam is mounted a set of, in this case and by way of example, three ladders 4 in such a manner that they can be adjusted between an angle of about 45° and the horizontal plane. On each ladder 4, further details of which are given hereinafter, there is fixed a funnel 5 wherein scraper belts 6 are rotatably mounted. The scraper belts 6 carry transverse upright scrapers 7 (more details of these scrapers are shown in figures 3, 4 and 5).
The length and the size of the funnel are calculated in such a manner that it allows to dredge or scrape up to a sufficient depth and to transport the dredged mud within each funnel by each set of scraper belts and scrapers cooperating therewith.
From figure 4 it can be deduced amongst others that each funnel 5 is delimited in the longitudinal direction by a top plate 8 and by a supporting plate comprising upright walls 9'. On the frontside, this is at the bottom of the funnel 5, where the sludge is dug up, the lowermost plate 9 ends in the shape of an either or not adjustable knife 9" which is an extension of the lowermost extremity of the lowermost plate 9.
When use is made, as in the described embodiment, of three funnels 5 disposed next to one another, they can preferably be mutually connected by crossbeams 10 which connect the longitudinal beams 11 of different ladders, locally to one another. The scraper belts 6 are guided around gear wheels 12 at the upper and lower extremity of the longitudinal beams 11.
Since the dredger according to the invention should not be equipped with propellers because they would inevitably stir up the water in the small water courses and in the case that the use of anchor cables on winding drums is for example not flexible or desired, the dredger is moved forwards by means of one or more drive wheels 13. These drive wheels 13 are equipped with radial pins or blades 14, the length of which may possibly be adjustable. In this way, they grip easily into the submerged bottom which is to be dug up and ensure the displacement of the dredger. These wheels 13 can be driven preferably independent from one another so that they can rotate each separately in different directions and/or at different speeds. If necessary, use can be made in an analogous way of an adjustable arm 15 mounted onto the stern of the dredger, which arm is provided on its free extremity with at least one drive wheel 16 which is preferably also provided with similar radial pins 17 or blades. When no use is made of the drive wheels 13 at the bottom of the ladders 4 for the propulsion of the dredger, it can therefore be moved forward by means of one or more drive wheels 16 on the lower extremity of the arm 15.
The ladders 4 can be adjusted under the desired angle, usually in function of the thickness and the level of the sludge layer or submerged bottom to be dug up, by making use of the structure which is shown in figures 6 and 7. Figure 6 shows guiding profiles 18 which are bent downwards above the stam of the dredger and which are fixed on shores 19. Preferably two of such guiding profiles and in particular the two middle most profiles carry a rack, indicated schematically by reference 20 in figure 6, the gear wheels 21 fixed on axles 22 cooperate with. The axles 22 are driven by a motor 23 in one direction or the other in such a manner that the ladders can be disposed in positions which vary between the horizontal position, shown in mixed line in figure 1, and the position under an angle of about 45° as shown in full lines in the same figure 1 and further in figure 6. The axles 22 driven by a motor are mounted in pieces 24 belonging to one of the transverse beams 10. The outermost ladders are only provided with free running wheels 25 (figures 6 and 7).
A variant embodiment of the device for pulling up the ladders as shown in figures 6 and 7 is represented finally in figure 8.
The ladders 4 or at least the two outer ladders can be provided sideways with a U-shaped gutter profile 26, while two or more support plates 27 are mounted on the dredger which are each provided with a pivot 28. This pivot fits in the U-shaped gutter profile 26. The ladders can be pulled up through a cable 29 upto a position which corresponds substantially to the horizontal plane. These structures can be constructed easily and are moreover simple to control.
In view of the very particular tasks for which the dredger according to the invention is designed, it is finally further provided with at least two but preferably four horizontally displacable arms 30 which serve as so-called "fenders" and which are provided hereto with wheels 31. The arms 30 can be displaced hydraulically, mechanically through a rack or manually and can be brought in this way in a predetermined position in order to block the dredger in its correct position. Thanks to said arms 30 provided with wheels 31, the dredger can also be displaced laterally either between two banks or two embankments or between walls, when the watercourse flows through a built-up area, such as a city. By operating the displacable arms 30, the dredger can also be positioned in its correct position on a minimum distance from a bank, an embankment or a wall.
For removing the sludge collected in the bulk hold 2, use is made of any known technique which does not belong to the essence of the present invention.
The advantages of the dredger, the very original concept of which is described hereinabove, are very clear. The dredger can be maintained in its correct position under very particular circumstances without requiring the use of anchors, howsers or piles. Due to the scraping in the closed funnel, very little mud arrives in the surrounding water so that the desired result, i.e. a reduced or nearly unexisting stirring up and no dilution of the mud with water, is obtained. Due to their concept, the scraper belts can be moved in their funnels in either one of both directions. Notwithstanding the limited dimensions of the dredger, it has a very large dredging or scraping capacity because the amount of transported water is insignificant compared to the displaced amounts of sludge and/or other sediments.
The invention is of course not limited to the hereabove described embodiment and it could be modified in many ways without leaving the scope of the claims.

Claims

A dredger equipped with at least one funnel (5) which is adjustable under an arbitrary angle which contains a scraper belt (6) for digging up sludge and other light sediments, characterized in that the scraper belt (6) is extending up to the lowermost part of said funnel (5) which lowermost part of the funnel (5) end in a scraper blade (9") so that sludge and other light sediments can be transported along said funnel (5).
A dredger according to claim 1, characterized in that said scraper belt (6) carries transverse scrapers (7) which extend to the side walls (9') of the funnel (5).
A dredger according to any one of the claims 1 - 2, characterized in that arms (30) adapted to be displaced sideways in the horizontal plane are provided for positioning the dredger with respect to banks, walls of a canal, a river or a narrow waterway.