GB2250450A

GB2250450A - Spillage recovery

Info

Publication number: GB2250450A
Application number: GB9125630A
Authority: GB
Inventors: Samir Abed Issa Albasri
Original assignee: Individual
Current assignee: Individual
Priority date: 1990-12-03
Filing date: 1991-12-02
Publication date: 1992-06-10
Anticipated expiration: 2011-12-02
Also published as: GB2250450B; GB9125630D0; GB9026233D0

Abstract

Spilt oil is recovered by the surface of open water by a submarine unit 15, suspended from floats (14) below the surface and receiving oil from the surface through a duct 20, which feeds an oil-water mixture into a two-stage gravity separation system 31, 32 from which the separated oil is fed into a continuous plastic tube 43 in the manner of a sausage machine. Successive portions 44 of tube 43 are sealed, full of oil, and discharged to the surface via outlet 21 for later recovery. System 31, 32 comprises tanks 31A, 31B used alternately and a flexible gravity settling bag 32. A captive balloon (23) above the surface carries navigational and surface scanning equipment. Duct 20 receives oil from a surface skimming device towed by a surface boat (Fig. 3). <IMAGE>

Description

SPILLAGE RECOVERY This invention relates to spillage recovery. It is particularly concerned with the recovery of substantial immiscible liquids (such as hydrocarbons) from water when such liquids are spilt on fresh or salt water.

Spillage of hydrocarbon liquids on a substantial scale tends to occur by accident and with little or no warning period. If the spillage is in an exposed position in conditions or sea disturbance andlor strong winds, such as at sea, near a coast or in a large river estuary, the spillage will be rapidly dissipated over a wide area. Recovery, or at least limiting spreading, of the spillage is currently difficult to achieve and near land if ineffective will result in a swift major hazard to the environment.

For any recovery operation to be effective it must be possible to initiate it promptly and get the necessary equipment and services to the site of the spillage as soon as possible. Such an operation must ensure that any spillage is recovered, or at least prevented from spreading from, the initial spillage area. In practice this latter requirement has proved difficult, if not impossible, to meet in any but the most sheltered conditions and with small amounts of spillage.

According to a first aspect of the present invention there is provided a method of recovery for a liquid floating on a base liquid comprising the steps of: 1 sweeping the floating liquid into a duct; 2 displacing the liquid along the duct to an outlet shrouded by a tube of plastics material; 3 closing off an initial part of the tube to define a subsequent working portion of tube; 4 filling the working portion with displaced liquid; 5 closing the working portion following the displacement into it of a selected amount of displaced liquid; and 6 detaching the enclosed working portion from the remainder of the tube and securing it pending a subsequent recovery operation.

According to a second aspect of the present invention there is provided a recovery device for liquid floating on a base liquid comprising: a rigid carrier of tubular form having an upstream inlet and a downstream outlet; a duct linking the upstream inlet to a recovery scoop; a supply of plastics material tubing located around the rigid carrier and adapted to have one end drawn off the carrier co-axially with the downstream outlet so as to enclose any material leaving the outlet; and means for sealing off the tubing so as to isolate liquid tightly a given length thereof from an adjacent length.

Preferably the recovery device includes a severing means to enable a sealed length of plastics tubing to be severed from a length retained on the carrier.

According to a third aspect of the present invention there is provided a recovery device comprising: 1 a flotation assembly comprising one or more buoyant devices adapted for floating on water; 2 a submarine unit adapted for attachment to the flotation assembly for support by the flotation assembly when the unit is immersed; 3 a displacement unit whereby liquid from water on which the assembly is floating can be drawn by means of a supply duct to the interior of the submarine unit; 4 a holding tank in the submarine unit for retaining liquid from the displacement unit; 5 a packaging unit in the submarine unit incorporating a tube of plastics material and means for periodically closing off lengths of the material to provide a sequence of sacs thereof; 6 a metering system in the submarine unit adapted to feed a discrete quantity of liquid from the holding tank into a sac; and 7 a dispensing outlet from the submarine unit whereby sacs can be released from the unit to rise to the surface of water in which the submarine is immersed.

Preferably the dispensing outlet is coupled by a flexible guide to a housing to retain sacs within a predetermined volume.

According to a fourth aspect of the present invention there is provided a recovery device according to the third aspect incorporating a balloon assembly attached to the submarine by a tether, the balloon assembly incorporating monitoring devices, such as cameras, whereby with the balloon located at an altitude above the submarine the surface area in the vicinity of the submarine can be scanned for floating liquids or other material, and means for recovering such information by way of the tether to the submarine. Typically the recovery device incorporates means whereby information gathered by the monitoring devices can be relayed to a location remote from the submarine.

Preferably the monitoring devices incorporate monitors to enable a given surface area to be scanned for floating liquids or other material by way of at least two different frequencies of electromagnetic radiation.

An exemplary embodiment of the invention will now be described with reference to the accompanying drawings of an oil spillage recovery unit of which: Figure 1 is a view of an immersed submarine unit; Figure 2 is a view of the interior of the unit shown in Figure 1 with additional items; and Figure 3 is a diagrammatic view of a recovery unit.

An item appearing in both figures is given the same reference in both.

Figure 1 shows an area of sea water having a surface 11 on which an oil spill 12 is spreading which needs to be recovered to prevent further spreading and environmental pollution.

A flotation assembly 13 comprises an number of air filled floats 14A, 14B, 14C, 14D which support submarine unit 15 by way of cables- typically cable 16. The assembly 13 serves to provide a fixed level for the submarine unit 15 which contains a winch for each cable (typically winch 17 in Figure 2) whereby the submarine unit 15 can be raised or lowered to a selected depth. Operation of the winches can also be used to trim the submarine unit when in use to overcome changes arising from movement within the submarine of quantities of material having a density differing from that of water.

Keel 18 is attached by cables 19 to the submarine unit 15 to stabilise motion of the submarine unit 15.

The submarine unit 15 contains equipment described hereafter in connection with Figure 2 whereby spilled material 12 drawn from the surface 11 by way of a duct 20 is packaged in discrete amounts for storage.

A dispensing outlet 21 provides for the release of packaged spillage from the submarine unit 15.

A propeller 22 is powered by way of a battery powered electric motor within the submarine unit 15.

A balloon 23 is attached to a mounting 24 on the top of the submarine unit 15 to support communication equipment enabling the operational state of the submarine unit 15 to be monitored and regulated. In addition the balloon incorporates scanning monitors adapted to scan the surface in the vicinity of the submarine to locate floating material. Information recovered by the monitoring units can be used to provide navigafional information such as to enable the submarine to be appropriately located for recovery operations. If necessary the information gathered by the monitors and other equipment in the balloon can be transmitted to a remote location to provide for overall operational management.

Access to the submarine is by way of a watertight hatch 25.

Figure 2 Inlet end 30 of the duct 20 opens into the first holding tank 31A (a second tank 31B being on standby) from which spillage material is pumped to a separation unit 32 by way of pipe 33. A suitable separating device for this purpose is described in my co-pending application 9016978.3 entitled 'Immiscible liquid separation'. The separation unit 32 includes a plastic bag 34 whose volume can be varied by way of an upper pair of rollers 35. The mixture of spilled material and water is allowed to settle for a period in the bag until a clear boundary exists between them. A pair of scissor arms 37 serve for clamping about the bag 34 at the position of the boundary between the spilled material and water so as to isolate the spilled material, in this case oil, in upper volume 38 of the bag 34 and the water in lower volume 39.The water in the lower volume 39 is thereafter pumped out by way of duct 40. The oil is displaced out of upper volume 38 by way of duct 41 into tube 42 which is enveloped in a tube 43 of plastics material. Outer end 43A of tube 43 is seam welded closed.

Following the displacement of a given amount of oil into tube 43 a sac 44 is formed by a further seam welding operation which sac is then cut free.

Complete and sealed sacs are released from the submarine unit 15 by way of a dispensing outlet 45 from which the sacs float to the surface 11 under the restraint of a flexible net tube 46 to a capture area shrouded by retaining nets N supported by floats F. The retaining net N is located at a depth to ensure that the retained sacs are not subject to any severe surface conditions of wind and water as may exist.

This recovery and packaging operation is maintained until spillage is entirely recovered or until the contents of tanks 31A and 31B have been emptied or whatever. By packaging the recovered material as described it can be retained and recovered without the need for urgent action. In this way urgent action can be directed merely to the gathering of the spilled material into the holding tanks 31A, 31B. The packaged material in this embodiment is shown in relatively small packages. However the size of a package can be relatively unlimited and is governed by the most convenient size which can be handled in the conditions.

In the event upper volume 38 is filled with water then it can be pumped directly out of the submarine by way of duct 47 rather than through the packaging system fed by duct 40.

Figure 3 shows the collection of spillage material and its feeding into the surface end of duct 20. A flexible collection duct 50 has a split u#pstream end 51 with limbs 52, 53 defining an area 54 between them. The end 51 is attached by a network of cables 55 to a towing bollard 56 on a power boat 57 in such a way that the path of the area 54 relative to the course of the boat 57 can be regulated and maintained with the boat 57 under way. Inner faces of the limbs 52, 53 facing into the area 54 are equipped with openwork mesh so that with the boat 57 travelling through the water spillage material guided into the area 54-is caused to pass by way of the duct 50 into holding tank 31A of the submarine unit 15 for subsequent packaging as described earlier.

In use the submarine unit 15 and its ancillary equipment is moved to a spillage incident (such as by a helicopter) and released and located in position.

Thereafter boat 48 is connected to duct 41 by way of cables 46 and the boat 48 driven so that area 45 is swept around the boundary of the spillage so as to collect spilled material for storage in convenient volumes in sacs such as sac prior to controlled disposal.

Control of the operations in the submarine 15 can be undertaken either by an on-board operator or by a remotely operated system with or without the application of data processing systems. The use of a wireless and! our television link is facilitated by lines extending through the cable linked to balloon 23.

The submarine unit 15 is shown as a closed volume containing various items of equipment. It is not envisaged that the unit will operate at any great depth and so the hull will not need to sustain any great hydraulic pressure. However as an alternative to a submarine unit with a closed, pressurisible, hull it is also envisaged that the hull can be an open structure serving to locate the various components, machines and tanks necessary to carry out the operations described which in any event oblige the spilled material to be contained in tanks, ducts and tubes which are necessarily spillage tight. In such an openwork structure divers could readily observe, and if necessary regulate, the operation of equipment and even restock, service or replace components in view of the ready access to the interior of the unit.

If separation is deemed advisable during the recovery process described then the submarine vehicle can incorporate a separation unit (such as referred to in my co-pending application 9118733.6).

Claims

A method of recovery for a liquid floating on a base liquid comprising the steps of: 1 sweeping the floating liquid into a duct; 2 displacing the liquid along the duct to an outlet shrouded by a tube of plastics material; 3 closing off an initial part of the tube to define a subsequent working portion of tube; 4 filling the working portion with displaced liquid; 5 closing the working portion following the displacement into it of a selected amount of displaced liquid; and 6 detaching the enclosed working portion from the remainder of the tube and securing it pending a subsequent recovery operation.

A recovery device for liquid floating on a base liquid comprising: a rigid carrier of tubular form having an upstream inlet and a downstream outlet; a duct linking the upstream inlet to a recovery scoop; a supply of plastics material tubing located around the rigid carrier and adapted to have one end drawn off the carrier co-axially with the downstream outlet so as to enclose any material leaving the outlet; and means for sealing off the tubing so as to isolate liquid tightly a given length thereof from an adjacent length.

A recovery device as claimed in Claim 2 including a severing means to enable a sealed length of plastics tubing to be severed from a length retained on the carrier.

A recovery device comprising: 1 a flotation assembly comprising one or more buoyant devices adapted for floating on water; 2 a submarine unit adapted for attachment to the flotation assembly for support by the flotation assembly when the unit is immersed; 3 a displacement unit whereby liquid from water on which the assembly is floating can be drawn by means of a supply duct to the interior of the submarine unit; 4 a holding tank in the submarine unit for retaining liquid from the displacement unit; 5 a packaging unit in the submarine unit incorporating a tube of plastics material and means for periodically closing off lengths of the material to provide a sequence of sacs thereof; 6 a metering system in the submarine unit adapted to feed a discrete quantity of liquid from the holding tank into a sac; and 7 a dispensing outlet from the submarine unit whereby sacs can be released from the unit to rise to the surface of water in which the submarine is immersed.

A recovery device as claimed in Claim 4 incorporating a separation unit is associated with the holding tank to provide for the separation of liquid from base liquid.

A recovery device as claimed in Claim 4 wherein the dispensing outlet is coupled by a flexible guide to a housing to retain sacs within a predetermined volume.

A recovery device as claimed in Claim 4 incorporating a balloon assembly attached to the submarine by a tether, the balloon assembly incorporating monitoring devices, such as cameras, whereby with the balloon located at an altitude above the submarine the surface area in the vicinity of the submarine can be scanned for floating liquids or other material, and means for recovering such information by way of the tether to the submarine.

A recovery device as claimed in Claim 7 incorporating means whereby information gathered by the monitoring devices can be relayed to a location remote from the submarine.

A recovery device as claimed in Claim 7 or Claim 8 wherein the monitoring devices incorporate monitors to enable a given surface area to be scanned for floating liquids or other material by way of at least two different frequencies of electromagnetic radiation.

A method of recovery as hereinbefore described with reference to and as illustrated in the accompanying drawings.