WO1994028254A1

WO1994028254A1 - Oil skimmer

Info

Publication number: WO1994028254A1
Application number: PCT/GB1994/001203
Authority: WO
Inventors: Michael James Dorey; David Charles Barham
Original assignee: Vikoma International Limited
Priority date: 1993-06-02
Filing date: 1994-06-02
Publication date: 1994-12-08
Also published as: GB9311382D0; GB2278553A

Abstract

An oil skimmer has a circular hopper (1) with a weir (2) at its upper end and an inwardly sloping inner wall (3). An aperture (4) at the bottom end of the hopper (1) feeds a pump (5) connected to a discharge hose (6). Floats (14, 15 and 16) support the skimmer at a height when floated in water such that the weir (2) is just below a nominal water level (17) so that oil floating on the water will pass over the weir (2) into the hopper (1). A weighted body (18) is suspended within the hopper (1) from a superstructure (22) by a hydraulic cylinder (23) whereby the height of the weighted body (18) with respect to the hopper (1) can be varied to affect the effective weight of the skimmer by varying the weight of the weighted body (18) which is supported by the water. This will vary the height of the lip (2) with respect to the water level (17) i.e. raising the body (18) will lower the lip (2) with respect to the water level (17).

Description

OIL SKIMMER

The invention relates to oil skimmers.

Oil skimmers have been previously provided to float in polluted water and have included a weir maintained at a vertical height slightly below the surface of the polluted water so that oil and other pollutants floating on the surface of the water pass over the weir and enter a hopper which may, for example, be of circular form in plan. Extraction means are provided to evacuate the pollutants from the hopper.

One problem that has arisen when skimming oil from the surface of water with a weir-typed skimmer is that it is necessary to have close control of the depth of the weir lip, in order to collect a maximum amount of oil and a minimum amount of water, and with a floating skimmer the depth of the weir is usually pre-set by adjustment of floats and sometimes by a floating collar at the weir lip.

As the oil flow varies, the amount of oil contained in the hopper at any time varies and this changes the weight of the skimmer. A hopper which is filling causes an increase in weight which lowers the weir lip and aggravates the situation by increasing the inflow. Conversely if oil flow over the weir slows then the extraction means of the hopper will rapidly empty the hopper, thereby lightening the skimmer and causing it to rise further to reduce the oil flow.

According to the invention there is provided an oil skimmer comprising a hopper, a weir over which oil can flow to enter the hopper and buoyancy means to support the weir at a level slightly below the level of the surface of liquid in which the oil skimmer floats, wherein a body is provided suspended within the hopper to reduce the volume of the hopper such that the effect of weight variations caused by filling and emptying of the hopper are reduced and means are provided to raise or lower the body with respect to the weir, which body is always at least partially submerged, thereby to change the effective weight of the oil skimmer and the height at which it floats in a liquid.

The body is preferably a sealed body which can be filled with water or otherwise weighted, whilst being suspended within the hopper, to give an approximately equivalent loading to a constantly full hopper. Preferably the means to raise or lower the body are hydraulic means under manual or automatic control.

Raising or lowering a weighted body affects the buoyancy of the oil skimmer thereby to adjust the weir height. Raising the body will increase the flow area within the hopper to suit the increased flow over the weir which will occur due to resultant lowering of the weir lip.

The pump provided for the oil skimmer is preferably a positive displacement lobe-type pump which can pump highly viscous fluids, can have a high efficiency, can tolerate prolonged dry running and is relatively choke-free in operation due to large in-and-out flanges.

The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:

Figure 1 is a perspective view of an oil skimmer according to the invention;

Figure 2 is a partial elevation of the oil skimmer of Figure 1;

Figure 3 is a plan view corresponding to Figure 1; and

Figure k is an elevation corresponding to Figure 1.

Referring to the drawings, an oil skimmer comprises a hopper 1 in the form of a circular body having a weir 2 at its upper end and an inwardly sloping inner wall 3- An aperture 4 at the bottom end of the hopper 1 feeds the housing of a pump which is connected to a discharge hose 6. The hopper 1 is mounted on skids 7- Arms 8, 9 and

10 are connected to the pump housing 5. extend radially and at their outer ends have vertical members 11, 12 and 13 respectively on which floats 14, 15 and 16 respectively are mounted. The floats 14, 15 and

16 support the skimmer at a height when floated in water such that the weir 2 is just below the nominal water level 17 indicated in Figure 2.

Oil floating on the water will pass over the weir 2 into the hopper 1 within the space thereof defined by the sloping wall 3 and will be pumped by the pump 5 into the discharge hose 6 to be conveyed to a remote storage tank.

Suspended within the hopper 1 is a weighted body 18 having a flat upper surface 19 and an under surface 20 which is generally parallel to the inner surface 3 of the hopper 1. Upstanding legs 21, preferably four in number, support a superstructure 22 from which the weighted body 18 is supported with the interposition of a hydraulic cylinder 23- By means of the cylinder 23 the height of the weighted body 18 with respect to the hopper 1 and thus the cross sectional area of a passage 2-i between the underside 20 of the weighted body 18 and the upper wall 3 of the hopper 1 can be varied. Operation of the cylinder 23 will also affect the effective weight of the skimmer by varying the weight of the weighted body 18 which is supported by the water and thus vary the height of the lip 2 with respect to the water level 17- Thus raising the body 18 will lower the lip 2 with respect to the water level 17- Figures 1, 3 and 4 show that the discharge hose 6 and hydraulic hoses 2 from the cylinder 23 can be led to an interface plate 26 at which connections to shore or to a mother ship can be effected. Hydraulic hoses 27 preferably also extend from the plate 26 to a hydraulic motor which drives the pump 5- The arms 9 and 10 can be provided with vertical pivots, one of which 28 can be seen in Figure 1 so that they can be folded to a position generally parallel to the arm 8 for ease of transport of the skimmer.

Claims

1. An oil skimmer comprising a hopper, a weir over which oil can flow to enter the hopper and buoyancy means to support the weir at a level slightly below the level of the surface of liquid in which the oil skimmer floats, wherein a body is provided suspended within the hopper to reduce the volume of the hopper such that the effect of weight variations caused by filling and emptying of the hopper are reduced and means are provided to raise or lower the body with respect to the weir, which body is always at least partially submerged, thereby to change the effective weight of the oil skimmer and the height at which it floats in a liquid.

2. An oil skimmer according to claim 1, in which the body is a sealed body which can be filled with water or otherwise weighted, whilst being suspended within the hopper, to give an approximately equivalent loading to a constantly full hopper.

3. An oil skimmer according to claim 1, in which the means to raise or lower the body are hydraulic means under manual or automatic control.

4. An oil skimmer according to claim 1, in which raising or lowering the weighted body affects the buoyancy of the oil skimmer thereby to adjust the height of the weir thereof.

5- An oil skimmer according to claim 4, in which raising the body increases the flow area within the hopper to suit increased flow over the weir which will occur due to resultant lowering of a lip of the weir.

6. An oil skimmer according to claim 1, in which a pump provided for the oil skimmer is a positive displacement lobe-type pump which can pump highly viscous fluids, has a high efficiency, can tolerate prolonged dry running and is relatively choke-free in operation due to large in-and-out flanges.

7. An oil skimmer substantially as hereinbefore described and with reference to the accompanying drawings.