The ‘Force 7’ Offshore Oil Recovery System applies the well proven principle of oil recovery by polypropylene mop fibre in the most efficient and economical way possible.

• Utilises the very effective opec mop
• No need for oil containment booms
• Only one vessel of opportunity needed
• Easily manoeuvrable to follow the oil as the slicks disperse
• Polypropylene mop recovers all oils and floating chemicals even in nominal film thicknesses
• Capable of recovering up to 70 tonnes of oil an hour (or 420 barrels an hour)

The system consists of four basic elements:

• The machinery unit for the mop drive, oil extraction and mop storage, complete with hydraulic power unit, controls, hydraulic crane and paravane handling winches.
• The polypropylene net.
• The Paravane
• Flexible tanks for storage and transport of recovered oil, if required.

Operational Method

The Paravane is launched, using the hydraulic crane, and streamed on its control wires. By adjusting the control wires the paravane will naturally take station at any point on the quarter of the vessel. These wires then act as a guide for the front of the net, to ensure that it opens up in the correct shape, clear of the vessels’ side, at the optimum position for collecting oil. The paravane remains in position throughout the operation, while the net is repeatedly cast and recovered, using the following cycle:

		1. The net is deployed astern. As the front of the net passes over the ship’s stern its outboard end is clipped to the aft paravane control wire. The head ropes continue to pay out, allowing the net to stream further astern while its’ mouth opens as it slips out along the wire.
		2. Once the net is fully deployed it is left in position until saturated, the time needed for this will depend on the thickness of the slick the size of the windrows and the speed of the vessel.
		3. Once the net is saturated it is recovered, passing through the squeeze rollers and scrapers as it is wound onto the storage drum. The recovered oil falls into the buffer tank from where it is piped to the storage transport tanks, (or Flexitanks) by the integral transfer pumps. 4. The cycle is then repeated. The average duration of the cycle is 9 minutes.

Recovery Rates

Projected recovery rates giving a guide to performance based on actual experience, and which assume constant encounter of oil at uniform thickness are as follows:

• 5 tonnes/hour at 100 micron film thickness
• 35 tonnes/hour at 1mm film thickness
• 56 tonnes/hour at 2mm film thickness
• 70 tonnes/hour at 6mm film thickness

Force 7 Efficieny

The use of this principle already gives certain advantages which ensure operational efficiency:

• A wide range of oil viscosities and emulsions can be effectively recovered using the mop.
• Recovery is still possible in thin oil layers, so that the system is not restricted by the limitations and expenses of containment booms and associated deployment vessels.
• The ability of the fibre to stay in the oil layer is not affected by sea state so that it is still working at maximum efficiency even in Force 7 conditions.

These are enhanced by design features which ensure cost efficiency:

• The system comprises of a single portable module allowing it to be stockpiled economically and despatched quickly to a spill, ensuring economy in capital outlay.
• Use of up to two units per ship ensures maximum vessel utilisation and economy in operating costs.
• The machinery is straightforward and robust requiring a minimum of operating personnel, and economical servicing and spares ensure low running costs.

For a more descriptive look at how a Force 7 looks and operates go to the Force 7 image gallery.

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