GB2045658A - Method and apparatus for producing an underwater abrasive slurry - Google Patents

Abstract

A method of producing an underwater abrasive slurry comprising injecting fluid under pressure into a submerged vessel containing abrasive material to generate the slurry, and removing the slurry from the vessel. The slurry may be removed by suction treated by a gun adapted to deliver the slurry to a surface to be treated. <IMAGE>

Description

SPECIFICATION Method of and apparatus for producing an underwater abrasive slurry This invention relates to a method and apparatus for producing an underwater abrasive slurry. Such slurries are used for cleaning structures, ships and the like underwater.

A method of producing an underwater abrasive slurry according to the present invention comprises injecting fluid under pressure into a submerged vessel containing abrasive material to generate the slurry, and removing the slurry from the vessel. The fluid is normally water and the abrasive material is normally sand.

The slurry may be removed by means of a suction line connected to a gun for delivering the slurry to a surface to be treated.

The fluid may be injected into the vessel from the top and the vessel may be substantially wholly filled with abrasive material to a predetermined distance below the top of the vessel.

Preferably the vessel is balasted so that it can be sunk to a convenient depth below the surface of the water and in this case the water may be permitted to enter the vessel through means preventing discharge of the abrasive material. The water entering the vessel may be directed so as to have a centrifugal component its motion. The arrangement is preferably such that direction of the motion of the fluid entering is such as to generate a toroidal mixing motion of the abrasive material and fluid.

According to one aspect of the present invention apparatus for producing an underwater abrasive slurry comprises a vessel capable of being submerged below the surface of the water and adapted to contain abrasive and having means for injecting pressure fluid in the vessel to cause agitation of the fluid and abrasive material so as to generate a slurry and means for delivering the slurry to be treated.

The vessel preferably has a suction line connected thereto through which the slurry is adapted to be delivered and conveniently the suction is created by a gun adapted to deliver the slurry to a surface to be treated.

The apparatus may include a nozzle for injecting fluid in to the abrasive material and a vessel may also have means adapted to admit the fluid but prevent the discharge of slurry from the vessel.

The vessel is preferable spherical and may have means for receiving balast and also means for tethering it to suitable anchorage means below the surface, e.g. magnets.

The invention may be performed in various ways and one specific embodiment will now be described by way of example with reference to the accompanying drawings in which.

Figure 1 is a cross-section through the apparatus according to the present invention.

Figure 2 is a plan view of the apparatus shown in Fig. 1 and Figure 3 is an underneath view of the apparatus of Fig. 1.

As shown in the figures the apparatus comprises a spherical Fig. 10 which a removable lid 11. The lid 11 is hinged as 12 to brackets 1 3 welded to the side of the sphere.

The lid 11 extends across the top of the sphere and is adapted to seal with respect to the sphere by means of a neoprene seal 14 retained in a groove 1 5 in a lid and which seals against a protecting rim 1 6 secured to the sphere. The lid can be tightened by means of hand wheel 1 7 in a conventional manner. The sphere is completed above the lid by a cap portion 18, which acts as strengthening but is not in contact with the material in the sphere.

The lid 11 carries at its centre a thick wall tube 1 9 the bottom of which is welded to the lid at 20 and is also welded just above its mid point to the gap 1 8. The tube 1 9 carries at its upper end the washer 21 secured to it but nuts 22 with a thick rubber joint interposed between the washer 21 and the top of the tube 19. The washer 21 carries at its centre a water injection pipe 32 and on the lower end of this, approximately level the top of the sphere is a knulnd nut 23 which carries a jet (not shown) through which water is injected to the sphere.

Also carried by the lid is an outlet pipe 24 which is normally a suction line with the suction being created by a gun at the surface to be treated. The outlet pipe 24 is welded to the lid and the sphere and through which the abrasive slurry is carried to the point of use.

The lid also carries a relief valve 25 and a handle 26 to assist with lifting. Fig. 2 shows an alternative position for the relief valve shown at 25a.

The base of the sphere indicated generally at 26 comprises an annular flange 27 having a downwardly directed outer ring 28. In the centre of the annular flange 27 is a removable circular plate 28. The circular plate is retainable by bayonnet fixing comprising large diameter recesses 31 in the plate communicating with smaller slots 32. Studs 30 mounted in the flange 27 have heads of larger diameter than the width of the slots 32, and the plate 28 can be inserted with heads 32 in the larger diameter openings 31 and twisted (by approximately 12") and the nuts tightened to secure the base in position.

At the centre of the base of the interior is a wear cone 34 which is removable and to this end is provided with a screw threaded opening at its base into which can be screwed a stud 35 attached to a handle 36. Thus when it is required to be replaced the base plate 28 is twisted and removed and the wear cone replaced.

Means (not shown) are provided for balasting the vessel and also for anchoring it and/ or for tethering it to a suitable anchorage, such as magnets.

In operation the vessel is filled with sand to a suitable level immediately below the lid and, the lid then closed and screwed down by means of the handle 1 7 to effect the seal and the apparatus is then lowered into the seal, and balasted and sunk to a predetermined level to suit a divers working depth. At this point it is tethered for example by means of magnets to a suitable surface which may be the length of an oil rig. A pressure balance valve 24 is provided so that if the operator does not completely fill the sphere with sand then this will open at approximately 1 p.s.i. to balance the pressure at great depth.

In order to produce a slurry water is fed through the high pressure inlet 32 through the jet and is arranged to produce a toroidal motion of the water and the sand to produce the slurry. The slurry thus formed is jetted through the exit pipe and is then supplied to the point of use which may for example be a slurry gun adapted to inject the slurry against a surface to be treated.

With the present invention it is possible for a diver to go down to considerable depths for example 500' or more to use only one pipe and which is branched adjacent the vessel to supply from the surface of the sea.

Claims (14)

1. A method of producing an underwater abrasive slurry comprising injecting fluid under pressure into a submerged vessel containing abrasive material to generate the slurry, and removing the slurry from the vessel.

2. A method as claimed in claim 1 in which the fluid is water and the abrasive material sand.

3. A method as claimed in claim 1 or claim 2 in which the slurry is removed by means of suction line connected to a gun for delivering the slurry to a surface to be treated.

4. A method as claimed in claim 1, claim 2 or claim 3 in which the fluid is injected into the vessel from the top.

5. A method as claimed in claim 4 in which the vessel is filled with abrasive material to a predetermined distance below the top of the vessel.

6. A method as claimed in any one of the preceding claims in which the vessel is balasted to that it can be sunk to a convenient depth below the surface of the water.

7. A method as claimed in claim 6 in which the water is permitted to enter the vessel through means preventing discharge of the abrasive material.

8. A method as claimed in claim 7 in which the direction of motion of the fluid entering the vessel is such as to generate a toroidal mixing motion of the abrasive material and fluid.

9. A method of producing an underwater abrasive slurry substantially as described herein with reference to and as shown in the accompanying drawings.

10. Apparatus for producing an underwater abrasive slurry comprising a vessel capable of being submerged below the surface of the water and adapted to contain abrasive material and having means for injecting pressure fluid into the vessel to cause agitation of the fluid and abrasive material so as to generate a slurry and means for delivering the slurry to a surface to be treated.

11. Apparatus as claimed in claim 10 in which the vessel has a suction line connected thereto through which a slurry is adapted to be delivered.

1 2. Apparatus as claimed in claim 11 in which the suction is created by a gun adapted to deliver the slurry to a surface to be treated.

1 3. Apparatus as claimed in any one of the preceding claims and having a nozzle for injecting fluid into the abrasive material.

14. Apparatus as claimed in any one of claims 10 to 1 3 in which the vessel also has means adapted to admit water but prevent the discharge of slurry from the vessel.

1 5. Apparatus as claimed in any one of claims 10 to 14 in which the vessel is spherical.

1 6. Apparatus as claimed in any one of claims 10 to 1 5 in which the vessel has means for receiving balast and also means for tethering it to suitable anchorage means below the surface.

1 7. Apparatus as claimed in any one of claims 11 to 1 6 in which the vessel has a removable base.

1 8. Apparatus as claimed in any one of claims 11 to 1 7 in which a removable wear cone is situated at the base.

1 9. Apparatus for producing an underwater abrasive slurry substantially as described herein with reference to and as shown in the accompanying drawings.