EP0665794B1

EP0665794B1 - Apparatus for collecting floating material from the surface of a liquid

Info

Publication number: EP0665794B1
Application number: EP92924066A
Authority: EP
Inventors: Ulf Hammarstedt
Original assignee: K L KONSTRUKTION AB; Kl Konstruktion AB
Current assignee: Kl Konstruktion AB
Priority date: 1991-04-30
Filing date: 1992-10-29
Publication date: 1997-05-14
Anticipated expiration: 2012-10-29
Also published as: SE9101298L; WO1994010026A1; SE9101298D0; DE69219793D1; EP0665794A1; SE468349B; AU2958892A

Abstract

The invention relates to a device for recovering floating material from a liquid surface. The device includes at least one drum (11A, 11B) to be rotated, partly immersed in the liquid, about a substantially horizontal axis (12). The curved surface (15) of the drum has at least one scoop (16A, 16B) formed by a depression in said surface, said scoop being gradually shallower in the intended rotational direction of the drum from a maximum depth by the radius of the curved surface increasing from a minimum to a maximum value. A conveying channel for receiving material carried down below the drum by the scoops is defined along the curved surface of the drum in the ascending section thereof by means of a stationary baffle (20). This baffle has an outlet portion joining means (18, 19) for taking over the raised material and extends substantially circularly along the curved surface of the drum spaced radially from the axis thereof a distance which corresponds substantially to said maximum radius thereof.

Description

The invention relates to a device for recovering floating material from a liquid surface, particularly for recovering oil from a water surface, including at least one drum to be rotated, partly immersed in the liquid, about a substantially horizontal axis, the curved surface of said drum being constructed for raising said material from the liquid surface, and means for receiving raised material.
Devices of this type are described in SE-B-394 204 and GB-A-2 007 516 the material being raised by means of vanes or buckets on a drum or a wheel, and also in DK-B-155 615 according to which the material is raised by means of a drum the curved surface of which consists of a helical barrel of net material.
The purpose of the invention is to provide a device of the kind referred to which has a considerably larger receiving capacity than the prior art devices mentioned above, particularly with regard to the recovery of oil from a water surface.
For said purpose the device according to the invention has obtained the characterizing features of claim 1.
In order to explain the invention in more detail reference is made to the illustrative embodiment diagrammatically shown in the accompanying drawing, wherein

FIG. 1 is a vertical cross sectional view of the device, and
FIG. 2 is a side view of one of the raising drums forming part of the device.

The illustrated device comprises a frame 10 shown partly only, which can form part of or is mounted on a vessel or also can be made stationary, e.g. in a cleaning plant for sewage or waste water. Two drums 11A and 11B rotatable in opposite directions each about a horizontal axis 12, are mounted in the frame. The rotational directions are indicated by an arrow 13 in FIG. 1, and it will be seen that the drums have the ascending sections of the rotational movement located adjacent each other. Each drum has two circular end walls 14, and a barrel 15 is provided therebetween said barrel consisting of an unperforated but preferably embossed metal sheet. The embodiment may be of the type appearing on floor plates and comprising raised and/or depressed portions (grooves) in a certain pattern. In the present case the barrel is shaped to form two depressions 16A and 16B each of which extends axially over the total length of the drum and peripherally over half the circumference of the drum. Each depression has an end wall 17 which is inclined in the range from 30 to 40° to the radial direction of the drum and slopes towards the bottom of the depression in the intended rotational direction of the drum. Adjacent the end wall 17 the depression has a maximum depth and then will be gradually shallower in the rotational direction of the drum up to the end wall 17 of the other depression by the radius increasing from a minimum value to a maximum value.
A screw conveyor having a screw 18 in a trough 19 is provided on the frame and extends in parallel with the axes 12 of the drums. The conveyor connects with other conveying means, not shown herein, which in turn connect with a collecting container, but the conveyor can of course also connect directly with such a collection container. At each side of the conveyor a baffle 20 connects with the trough, said baffle defining a conveying channel with the adjacent drum 11A and 11B, respectively. The baffle has an outlet portion connecting with the trough 19 and extending substantially circularly along the curved surface of the drum spaced radially from the axis thereof, the spacing corresponding substantially to the maximum radius of the drum at the outer edge of the end wall 17 or is slightly larger than said radius. The baffle has also a straight portion which forms an inlet portion of the conveying channel, wherein the radial distance of the baffle to the axis of the drum decreases in the intended rotational direction of the drum from a maximum value to said radial spacing in the outlet portion of the conveying channel. For each drum there is provided above the screw conveyor 18, 19 a flexible stripper plate 21 engaging the curved surface of the associated drum over the total axial length thereof between the two end walls 14.
When the device is operating, the drums 11A and 11B are immersed to a substantial extent into liquid - the liquid surface being indicated at 22 and is located slightly below the upper edges of the trough 19 so that liquid does not flow into the trough - and are rotated in the direction of the arrows 13. Then, the depressions 16A and 16B operate as scoops or buckets which in the descending section of the path of rotation of the drum carry material floating on the liquid, down under the drum and convey such material into the conveying channel defined by the baffle 20, wherein the material will be raised upwards partly under influence of the inherent floating buoyancy thereof, in order to pour down into the trough 19 where the material will be taken over by the screw 18 for transmittal to the collecting container. The path of the material during the recovery is indicated by heavy arrows in FIG. 1. The conveyance of the material in the rotational movement of the drum will be amplified by the curved metal sheet of the drum is patterned in the manner described. Material adhering to the curved surface of the drum will be stripped therefrom by means of the stripper blade 21 immediately above the water surface 22 so that the curved surface of the drum will be substantially clean when later passing again into the liquid. Conveyance of the oil to the trough 19 will be made more effective due to the fact that the material under the drum can collect in the deeper portion of the buckets and can be positively carried on in the movement of the drum and lifted by the end wall 17 through the conveyance channel defined by the baffle 20. The outer edge of the end wall 17 should pass as close as possible to the baffle so as to avoid that the material leaks backwards between said edge and the baffle.
The described embodiment of the invention can be modified in different manners and thus it is possible to arrange a single depression or bucket on each drum or to arrange more than two depressions or buckets, and it is also conceivable to arrange two or several series of buckets axially side by side on the drum, the buckets of each series being displaced peripherally in relation to the buckets in the other series. It is not necessary that the drums are cylindrical; they can also be conical with the small end pointing e.g. forward in the stem of a vessel on which the device is mounted. The screw conveyor 18, 19 can be replaced by a conveyor of another type, e.g. a belt conveyor or scraper conveyor. It is also possible to have the drums conveying the material directly to the collection container for this material when such container is provided close to the drums. The conveying channel defined by the baffle can extend over a larger or smaller portion of the circumference of the drum than has been shown herein. The end wall 17 preferably is inclined in the manner shown in order to facilitate transfer of the raised material to the conveyor 18, 19, but it is within the scope of the invention to arrange this end wall radially. Another type of stripper 21 than that shown herein can be provided depending on the material to be recovered and the character of the curved surface of the drum. As mentioned the curved surface preferably is patterned but it is not excluded to make the curved surface smooth, and in an embodiment which is intended particularly for recovery of very thick oil from water a smooth or patterned curved surface is provided with a net or a perforated or expanded metal sheet which follows the contour of the curved surface and is spaced from said surface a distance of the order of 1 to 5 cm. Finally, it should be mentioned that only one drum can be provided as can be the case particularly in stationary devices and that also more drums than two can be provided in the device.

Claims

Device for recovering floating material from a liquid surface, particularly for recovering oil from a water surface, including at least one drum (11A, 11B) to be rotated, partly immersed in the liquid, about a substantially horizontal axis (12), the curved surface (15) of said drum being constructed for raising said material from the liquid surface (22), and means (18, 19) for receiving raised material, characterized in that the curved surface (15) of the drum (11, 11B) forms at least one bucket (16A, 16B) as a depression in said surface, which from a maximum depth is gradually shallower in the intended rotational direction of the drum by the radius of the curved surface increasing from a minimum value to a maximum value, and that along the curved surface of the drum there is provided in the ascending section thereof a conveying channel defined by a stationary baffle (20), for reception of material carried down by the bucket below the drum, said baffle over an outlet portion connecting with said means extending substantially circularly along the curved surface of the drum at a radial distance from the axis of the drum, which corresponds substantially to said maximum radius of the drum.
Device according to claim 1,
characterized in that two or more depressions (16A, 16B) are provided in the curved surface distributed in the peripheral direction of the drum.
Device according to claim 1,
characterized in that the conveying channel has an inlet portion wherein the radial distance of the baffle (20) decreases in the intended rotational direction (13) of the drum (11A, 11B) from a maximum value to said radial distance.
Device according to claim 1,
characterized in that the curved surface (15) is patterned by having protrusions and/or depressions.
Device according to claim 1,
characterized in that a net or a perforated or expanded metal sheet is provided over the curved surface (15) and follows the contour thereof spaced from said surface.
Device according to claim 1,
characterized in that the bucket (16A, 16B) at the deeper end thereof is bound by an end wall (17) inclined to the radial direction, said end wall sloping towards the bottom of the bucket in the intended rotational direction (13) of the drum (16A, 16B).
Device according to claim 6,
characterized in that the inclination of the end wall (17) ranges between 30 and 40° to the radial direction.
Device according to claim 1,
characterized in that after said means for taking over the raised material (18, 19) as seen in the rotational direction (13) of the drum (16A, 16B) there is provided a stripper (21).
Device according to claim 1,
characterized in that said means (18, 19) for taking over raised material comprises a conveyor.