GB2308402A - Retaining polluting fluid in damaged containers - Google Patents

Abstract

A fluid container (3) comprises a flexible bladder (4) stored within and in fluid communication (8) with the container, pump means (10) for transferring fluid from the container into the bladder, sensor means for monitoring the condition of the container and control means responsive to the sensor means for activating the pump means (10) in the event of an emergency resulting in rupture of the container to transfer the fluid from the container into the bladder (4). The container may be an oil tanker, a tank lorry, or the fuel tank of a vehicle, e.g.

Description

LIQUID CONTAINER REPAIR SYSTEM This invention relates to a liquid container repair system and, more particularly, to a temporary repair system for a liquid container which can be quickly and efficiently deployed in the event of damage to the container to minimise the loss of liquid from the container.

Bulk liquid carrying vessels such as oil tankers offer a cost effective way of transporting large amounts of oil over very large distances. However, the potential damage to the environment due to an oil spillage if the vessel is damaged is considerable. Where damage occurs, it is often necessary to allow the oil in the vessel to seep out before the vessel can be recovered in order to minimise fire hazards. This practice can lead to large scale disaster for the surrounding plant and animal life. Furthermore, the effects of such an oil spillage are apparent for many years following the actual accident.

On a different level, problems can arise in vehicles where the fuel tank is ruptured for example, during a collision, causing a leakage of fuel from the vehicle onto the road surface. This presents both a fire hazard and also leads to dangerous driving conditions for other drivers.

The present invention aims to provide a safety system which will reduce the amount of liquid lost from a ruptured liquid tank such as an oil tank or the fuel tank of a vehicle in an emergency situation in order to overcome or at least mitigate the above disadvantages.

According to one aspect of the present invention there is provided a safety system for a fluid container comprising a flexible bladder stored within and in fluid communication with the container, pump means for transferring fluid from the container into the bladder, sensor means for monitoring the condition of the container and control means responsive to the sensor means for activating the pump means in the event of an emergency resulting in rupture of the container to transfer the fluid from the container into the bladder.

Conveniently, more than one bladder and pump means may be provided within a fluid container. This would reduce the time taken for the liquid to be transferred from the container to the membrane and reduce the amount of liquid lost from the container. This is especially important in the examples given above where the loss of fluid from the container leads to further problems for the environment or other road users.

Preferably, the pump means are hydraulic, although they may alternatively be mechanical, electrical or of any other type which are suitable for submerged operation in a liquid carried in the container.

Advantageously, the pump means is operated by carbon dioxide gas which has the added benefit of acting as a fire retardant.

One embodiment of the present invention will now be described with reference to and as shown in the accompanying drawings in which: Figure 1 is a schematic cross section of the hull of a vessel with a safety system according to one aspect of the present invention fitted; Figure 2 is a schematic cross section of the hull shown in Figure 1 with the safety system in an operating condition; Figure 3 is a schematic cross section of the hull shown in Figure 1 with the safety system in a fully inflated condition; Figure 4 is a schematic view of a safety system mounted in a road haulage vehicle; and Figure 5 is a schematic view of a safety system mounted in the fuel tank of a car.

Turning now to the figures, there is shown the hull of a liquid carrying vessel such as an oil tanker. In the figures, the hull 1 of the vessel 2 has been divided into two liquid tanks 3, 3' in order to illustrate the invention.

A flexible, liquid tight fabric membrane 4 is stored in a folded condition within each tank 3, 3'. The membrane has the form of a container with an opening 5 for the ingress of liquid.

The membrane 4 is held in the embodiment shown against the roof 6 of the tank 3, 3' by suitable mounting means (not shown). The membrane may be formed of any suitable material but must be inert to any chemical reaction from the liquid 7 stored in the tank.

A duct 8 leads from the opening 5 of the membrane 4 along the roof 6 of the tank and down one wall of the tank ending at the lowest point 9 in the tank. A submersible pump 10 is located at the end of the duct 8. The pump is capable of operating within any liquid 7 which is transported in the tank and may be hydraulic, mechanical, electrical of any other type.

A flexible feed (not shown) may be provided for the duct 8 in the event of tilting of the tank 3 where the liquid in the tank will not gather at the lowest most point 9 in the tank.

Sensor means (not shown) are provided within the tank 3, 3' to monitor the condition of the tank and to send a warning signal either to activate the pump 10 or to the bridge of the vessel 2 to warn the crew of the emergency situation.

In the event that the tank 3 is ruptured, for example if the vessel 2 is run aground as shown in Figure 2, the liquid 7 in the tank 3 begins to escape from the hole and a signal is generated by the sensing means and passed either to the bridge of the vessel or to the pump 10 directly.

When the pump is activated, either automatically or manually, liquid 7 is pumped from the lowest most point 9 of the tank 3, through the duct 8 and into the opening 5 of the flexible membrane 4.

As the membrane begins to fill with the liquid, it detaches from the mounting on the roof 6 of the tank 3 as shown in Figure 2 and begins to expand within the tank. As is clearly shown in Figure 2, only the pump 10 in the tank which is affected by the rupture is activated and the other tanks 3' in the vessel are unaffected in any way.

The pump 10 continues to pump liquid 7 from the tank 3 into the flexible membrane 4 until the contents of the tank 3 have been transferred and the flexible membrane 4 fills the volume of the tank as shown in Figure 3. The membrane is sufficiently strong to withstand the pressures which would tend to force it out of the rupture in the tank and provides a lining for the tank to prevent further loss of liquid 7 through the rupture.

With a large tank of the type shown, more than one flexible membrane 4 each with a dedicated pumping system may be provided in order to transfer the liquid 7 in the tank into the membranes as quickly as possible to minimise the amount of liquid lost through the rupture.

The tank 3 may be provided with a secondary system (not shown) for emptying the membrane 4 once the emergency situation is over and the rupture has been sealed. This may be in the form of a secondary pump connected to a flexible feed pipe within the tank 3 which would allow the liquid 7 to be discharged from the membrane.

With reference to Figure 4, there is shown a safety system mounted in the tank 11 of a road haulage vehicle 12.

In this embodiment, the pump 10 may be driven by a compressed CO2 cylinder 13 mounted behind the cab 14 of the vehicle or, if the vehicle's power system is operation, by a direct drive from its own pumping system via a suitable valve arrangement. The operation of the system is similar to that described above with respect to a liquid tank of a vessel.

Figure 5 shows a safety system mounted in the fuel tank 15 of a car 16. In this embodiment, the pump may be driven by a compressed CO2 13 cylinder located in the vehicle boot 17.

In the two examples given above, the compressed CO2 has the added advantage of acting as a fire retardant in the event of an emergency situation arising.

In a still further application of the invention in relation to bulk liquid carrying vessels, the system is fitted to the tank of a vessel which allows the tank to be washed at sea, the polluted liquid being pumped into the flexible membrane and stored until the vessel reaches port at which time the polluted liquid is pumped out of the membrane and removed from the vessel. This prevents polluted liquid being discharged into the sea and further saves time in port for the 'turn round' of the vessel.

This application could be applied to a variety of cargo vessels and storage facilities, ranging from very large cargo ships to road haulage vehicles and more general fixed installations. Any form of tank or container could have the system fitted.

It operates on the same principal as the ballast storage use described above and would allow the tanks to be regularly used for carrying different liquids without the need for thorough cleaning. This would facilitate making return trips with a full load, without cleaning, on a regular basis. The pumping and valve installation and control system would require modification and a stronger membrane would be required than if the system was reserved for emergency use only.

In a further embodiment the tanks and containers may be used for transporting gas as opposed to liquid or in fact any combination of the two.

In some cases, eg semi-submersible drilling rigs, barge cranes and ships generally, stability and attitude are controlled by pumping ballast to and from special tanks.

With a bulk liquid transfer and storage system as described above fitted control could be extended to allow a wider and more flexible use. In high performance ships and boats, as fuel is used up the ship becomes lighter and a trim is affected with a consequent loss of efficiency. If this system were fitted water could be progressively pumped into the membrane and the tank to counteract the effects of the lighter fuel load.

Furthermore, in floating vessels such as closed decked ferries, a large compressed air container could be fitted to the stored membrane which in the event of any danger of sinking would inflate the membrane to form a floatation device within the car deck, for example of the ferry. A similar device could be used for smaller passenger boats, pleasure crafts and yachts by locating a gas powered membrane in a suitable location.

It is further envisaged that a permanent body of water of perhaps one litre or so in depth could be kept in the bottom of the main tank of a tanker. A membrane would be filled with oil and the water at the bottom of the tank would form a protection zone in the event of a breach of the tank bottom as previously described. The ballast containment would act as described above except that in this case the ballast would be in the main tank as opposed to the membrane. In the event of the ship being grounded water in unaffected compartments could be temporarily pumped out to raise the ship until it was in deeper water. It would then revert to its normal trim. The membrane in this situation would have to be stronger than previously described. It might be fitted in an outer container, perhaps something similar to a trawler net to protect it from sharp edges within the tank and to assist in the event of side impact.

This could be of benefit in countries which require new ships to be built with double hulls.

It will be appreciated that the above described safety system can be retrofitted into the liquid tanks of vessels and the fuel tanks of vehicles. Furthermore, the safety system may be fitted to both fixed or moveable tanks, commercial, industrial, marine, off-shore installations, domestic (eg oil storage tanks) as well as all forms of transport, both as fuel and cargo containing systems. A portable version for example to be carried by emergency services is also envisaged.

This safety systems gives an effective protection to the environment from the rupture of vessels and also to other drivers in the event of a road accident where fuel spillage causes both a fire hazard and also dangerous driving conditions.

Claims (6)

1 A safety system for a fluid container comprising a flexible bladder stored within and in fluid communication with the container, pump means for transferring fluid from the container into the bladder, sensor means for monitoring the condition of the container and control means responsive to the sensor means for activating the pump means in the event of an emergency resulting in rupture of the container to transfer the fluid from the container into the bladder.

2 A safety system according to claim 1 and further including means for releasably mounting the bladder within the container.

3 A safety system according to claims 1 or 2 wherein the fluid communication between the bladder and the container is maintained by a flexible duct through which fluid is pumped into or out of the bladder.

4 A safety system according to any one of claims 1 to 3 wherein the pump means is driven by compressed CO2 gas.

5 A safety system according to any one of the preceding claims wherein the bladder is formed of a fluid type fabric material.

6 A safety system for a fluid container substantially as hereinbefore described with reference to and as shown in the accompanying drawings.