GB2229145A

GB2229145A - Toxic waste disposal to an abyssal plain

Info

Publication number: GB2229145A
Application number: GB8903095A
Authority: GB
Inventors: Karl Arne Kjell Eriksen
Original assignee: SCANDINAVIAN TMS CARGO HANDLIN
Current assignee: SCANDINAVIAN TMS CARGO HANDLIN
Priority date: 1989-02-10
Filing date: 1989-02-10
Publication date: 1990-09-19
Also published as: GB8903095D0

Abstract

A chamber 3 within the body of a floating vessel (i.e. a ship) is open to the sea at the bottom but sealed from the atmosphere at the top and by variance of the internal air pressure sea water level within the chamber can be varied. A hinged door 4 partially fills the bottom of the chamber 3 and is a platform for filling of collapsible flexible disposable containers 5 with toxic or non-toxic slurry pumped from tanks 2 within the ship. During filling of the container sea water level is raised to support the said container. When filled the container is sealed and by tilting of the door 4, the container slides downwards and falls to the seabed. Descent speed is regulated by built in flaps or pockets and direction assisted by steering fins. <IMAGE>

Description

TOXIC WASTE DISPOSAL TO AN ABYSSAL PLAIN This invention relates to a method of disposing of toxic or contaminated waste to the ocean depths.

Many shallow coastal regions of the world are infected by low to high toxically contaminated sediment originating from urban waste and industrial effluents.

This situation is worsening and even though nations are trying legislative actions to reduce continued pollution of the shallow seas, the problem will at best be slowed down, not reversed.

Furthermore, the problem becomes further aggravated when ports or harbours, normally situated in river mouths, require dredging and the spoils have to be disposed of. This leads to the toxic sediments being removed from these 'dead' waters and placed in areas where marine life will be heavily affected.

According to many scientific studies, little or no interaction takes place between water in the deep oceans and the surface regions (i.e. exceeding 2000 metres water depth and the shallower zones).

The difficulty is to contain the toxic sediment during the transit between the ocean surface and the abyssal plains or even deeper ocean trenches.

This invention resolves the problem in the following way: There is provided a specially built vessel or modified tanker which carries the toxic sediments in slurry form to the designated and approved place of dumping.

The vessel is equipped with a special chamber where specially designed flexible containers are filled by pumping. This special chamber is open to the sea at the bottom, but sealed from the atmosphere at the top, and by variance of the internal air pressure, sea water can be let into or pushed out of the chamber. This feature allows the flexible containers to be surrounded by water during filling (thereby reducing stresses in the container itself).

Filling of the flexible containers is achieved by pumping the slurry through a combination of rigid and flexible piping allowing the container to expand during filling. Overhead cranes are provided in the chamber to allow handling of the collapsed empty containers.

Once filled, the flexible container is disconnected from the piping, the entry sealed, and the bottom door underneath tilted, allowing the container to slide off and descend to its rest position on the ocean floor.

This disposable container will have flaps built into its construction which will reduce the speed of descent to prevent undue stress in the material and fins to aid in steering, maintaining a vertical descent.

The disposable container may break up upon impact with the seabed. To prevent part or parts of the container ascending to the surface, the material of the container must have a density greater than that of water.

Referring to the drawings, Figure 1 is a plan on the ship; Figure 2 an enlarged plan on the chamber; Figures 3, 4 and 5 are sections through the chamber (taken in the direction of the arrows shown on Figure 2).

Figure 1 shows the arrangement of tanks (2) containing slurry within the hull of the ship (1) and the discharge chamber (3). The arrangement of tanks and chamber may differ depending on the exact type of vessel used.

Figure 2 shows the bottom door (4) with its profiled side walls in a recess within the chamber bottom (3). The floor at the higher level (14) may be used for storage. Stairs (15) allow access between levels. Crane rails (16) for electric travelling hoists (23) are located above the bottom door (4) near the roof of the chamber (3). Compressors (23) draw air through ducts (24) to change air pressure within the chamber (3). The feed pipes (8) from the ships tanks (2) carry slurry to the manifold (7) and then to the boom arm (10) via a flow meter (12) and pipe (9). The boom arm (10) is either fitted with a counterweight (11) or is hydraulically operated.

Figure 3 shows the bottom door (4) raised and held by the hydraulic rams (17), and the hinge point (18). The door (4) rests at the forward end in a seat (19) which is part of the structure of the ship (1) and forms a working platform. Flexible piping (20) is connected to the flexible disposable container (5) at a nozzle (21) at the low level (19) and disconnected, after filling, from the platform (13). A guide (22) prevents the flexible piping (20) from wearing on the platform (13).

At the start of filling, the water level is at bottom door level. During filling, air pressure in the chamber (3) is reduced allowing the water level to rise thus supporting the container. Control of all operations is made from the control panel-(6).

Figure 4 is similar to Figure 3 but shows the flexible disposable container (5) filled, the water level is at the high level and the boom arm (10) has raised to maintain the pipework (20) in the correct relative position.

After filling is complete (container (5) filled by pre-determined volume of slurry, measured by flow meter (12)), the flexible piping (20) is disconnected from the nozzle (21) and a stopper fitted to the nozzle (21).

The filled container (5) can now be launched. This is achieved by extending the hydraulic rams (17) thereby increasing the angle of slope of the door (4), until the container (5) slides out.

After discharge of the container (5) through the bottom door (4), the water level in the chamber (3) can be lowered by increasing the air pressure using the compressors (23). The bpttom door (4) can now be raised.

The next flexible disposable container (5) can now be placed on the door (4) using the electric travelling hoists (23) operating from the crane rails (16), and the cycle repeated.

Figure 5 shows an empty container (5) positioned ready for filling on the bottom door (4).

Claims

1. A chamber within the body of a floating vessel containing a transfer facility to safely dispose and transport both toxic and non-toxic slurry to the deep ocean floor utilising flexible disposable containers launched from the said chamber, where the containers are supported during filling by being surrounded in seawater.

2. A chamber as described in Claim 1 wherein the chamber is open to the sea at its bottom and sealed from the atmosphere above sea level.

3. A chamber as described in Claim 2 wherein the level of seawater within the chamber is varied and controlled by variance of the air pressure within the chamber.

4. A chamber as described in Claim 1 wherein the chamber is open to the sea at its bottom and where the opening is mostly blocked by a hinged door.

5. A chamber as described in Claim 4 wherein the hinged door can be opened outwards and downwards by hydraulically operated rams allowing access to the sea beneath the vessel.

6. A chamber as described in the preceding claims where an empty flexible disposable container is placed upon the hinged door when seawater is nominally present within the chamber and as filling of the container progresses the seawater level is allowed to rise within the chamber by variance of the air pressure, thereby supporting the sides of the container being filled.

7. A chamber as described in Claim 6 wherein the flexible disposable container when filled and sealed shut slides down the hinged door, when opened outwards and downwards, out of the bottom of the vessel, and travels downwards to the deep ocean floor.

8. A chamber as described in Claim 1 wherein the flexible disposable container may be fitted with flaps or pockets to its external surface to increase drag and reduce the speed of descent to the deep ocean floor, and fins to assist with steering.

9. A chamber as described in Claim 1 wherein the flexible disposable container is made using a flexible material having a specific gravity greater than unity.

10. A chamber as described in Claim 1 wherein piping and pumping equipment is provided to enable the slurry to be pumped from the storage tanks within the vessel to the said chamber and hence to the flexible disposable container.

11. A chamber as described in Claim 8 wherein the flexible disposable container may be fitted with depth measurement means where the measured depth is transmitted to the launching vessel.

12. A vessel for disposal of waste to the ocean floor substantially as described with reference to and as illustrated in the accompanying drawings.