SPECIFICATIONA device for collecting and separating material floating on waterThe invention particularly deals with the problem of oil escaping from tankers, refineries and other installations. However it could also be used for the recovery of other liquids (and solids) floating on water. Oil will be used as an example in this description.
The basic device is a moving endless belt made of mesh or net and inclined at an angle to the water surface. It is provided with a means of removing the oil from the mesh and a device for preventing floating debris reaching the belt.
Previous devices for this purpose can be divided into four main types: those using the weir effect; those which increase the depth of the oil layer; absorption devices; those which involve adhesion. Weir-type devices consist of a barrier which allows the oil to flow over the top, but holds back the water. Waves reduce the effectiveness of these devices and a considerable amount of water is taken in with the oil, making further separation necessary.
The second type of device concentrates the oil layer by reducing its area and so increasing its depth until it is possible to pump it off. Slatted conveyors and archimedes screws have been used to achieve this effect continuously. Again waves cause problems with this method. Absorptive materials have been used to soak up the oil which is then squeezed out into a collecting tank. The main limitations of this method appear to be the rate of work possible and the amount of water taken up with the oil.
Absorption devices using discs or rollers have been proposed. The layer of oil adheres to the surface of the disc or roller and is removed by scrapers. Waves would tend to hinder the operation of these machines and they could create oil-water emulsions due to the disturbance of the surface layer.
The device described here uses the viscosity of the oil to suspend the layer on the mesh, while allowing the water to pass through. Collection and separation are carried out in one operation. The device is pivoted at its upper end and the lower end is supported by floats so that the collection point is just below the surface regardless of waves. This makes possible a high rate of work with minimal disturbance and emulsification, since the layer is lifted off the water with little change in its motion.
The device will now be described in detail with reference to the attached diagrams.
FIG. 1. is a side elevation of the basic device.
FIGS. 2 s 3 are plan views. FIGS. 4 to 7 show various ways in which the device might be used.
The device moves relative to the water in the direction shown by the arrows. The upper side of the conveyor (I) moves upwards at a speed adjusted to match the relative speed of the device through the water, so that the layer of oil is lifted with the minimum of disturbance. The water below flows through the holes in the mesh. The floats (7) maintain the bottom of the conveyorjust below the surface and may be shaped as shown inFIG. 2 to direct more oil on to the belt. They may also be pivoted. (FIG. 6). A device (8) may be provided to catch floating debris such as driftwood and weed, preventing them from reaching the belt.
In one embodiment (FIG. 2) this device may take the form of two sets of bars, divided in the middle and hinged at the outer ends so that the two halves may be'swung out when necessary to the position shown dotted in Fig. 2, causing the flow of water to remove the collected debris. In another embodiment, shown in FIG. 3, this part of the device may take the form of two opposite-handed sections of screw flights on the same rotating shaft. These would convey debris to either side of the collector. The device for clearing oil from the mesh (9) might take the form of a static or rotating brush or alternatively a scraper or roller. The upper roller (6) of the conveyor may be provided with a soft or stippled surface which protrudes through the holes in the mesh, forcing the oil out so that it can be more easily removed.The oil may be channelled into a collecting tank (10) by a chute or funnel (12). A pump (11) may be used to remove the oil to temporary storage tanks.
FIG. 4 shows the device installed in a selfpropelled, catamaran-type vessel, which may tow barges into which the collected oil can be pumped. Alternatively flexible containers might be deployed from the after-deck of the collecting vessel.
FIGS. 5A a B show two ways in which the device might be used in association with floating booms to increase the amount of oil collected. InFIG. 5A a single tug is shown towing the collecting vessel and the booms are held out by paravanes.
In FIG. 5B. two collecting vessels are towed by three tugs some distance apart with the booms between the tugs and the collectors. In reasonable sea conditions the number of vessels could be increased to cope with very large slicks in one pass.
FIG. 6 shows the device attached to a conventional vessel. This might be a small tanker allowing the oil to be pumped straight into its tanks. Two or more of the devices might be so attached.
FIG. 7 shows the device as a stationary installation on a river or stream which has become polluted. The oil collected could be pumped into road tankers or storage tanks nearby.
1. A device for collecting and separating a layer of immiscible liquid from the surface of water, by suspending the layer on a mesh which allows the water to drain through.
2. A device according to claim 1 in which the mesh takes the form of a continuous belt mounted at an angle to the water and rotating such that the upper surface moves away from the water surface.
3. A device according claims 1 and 2 provided
**WARNING** end of DESC field may overlap start of CLMS **.