GB2034787A

GB2034787A - Conveying apparatus for mud

Info

Publication number: GB2034787A
Application number: GB7932978A
Authority: GB
Original assignee: O&K Orenstein and Koppel GmbH
Current assignee: CNH Industrial Baumaschinen GmbH
Priority date: 1978-09-22
Filing date: 1979-09-24
Publication date: 1980-06-11
Also published as: NO793028L; GB2034787B; NL7906997A; CA1124753A; SE7907835L; IT1165995B; FR2453949A1; BE878919A; DE2841203A1; JPS5598595A; ES484278A1; IT7909540A0

Abstract

An apparatus for conveying mud from great water depths comprises mud-conveying piping B in which is interposed a suction pump D of a pump unit C including a pump E delivering pressurized sea water via a flexible conduit K to nozzles at a suction head L carried by the piping B. The suction mouthpiece of the head L is in the form of a conical screen of which the tip is directed downwardly. The screen is vibrated vertically, and the vibrations are damped relatively to the piping B by a spring damping part F. <IMAGE>

Description

SPECIFICATION Conveying apparatus for the conveying of mud from great water depths The invention relates to conveying apparatus for the conveying of mud, more particularly ore mud, from great water depths.

A conveying apparatus for the conveying of mud from great water depths is known which comprises a conveying pipe ending in a suction mouthpiece and provided with a conveying pump.

The outer end of the conveying pipe is guided in a cylinder in such a manner as to be mobile yet sealed peripherally. A drive device is engaged between the cylinder on the one hand and the outer end of the conveying pipe on the other hand and moves the two parts to-and-fro relatively to each other. The cylinder is provided with one or more inwardly opening non-return valves, and the conveying pipe with an upwardly opening nonreturn valve.

It is also known to construct the drive such that it serves not only for producing the pumping motion but also for producing high-frequency shaking vibrations. The lower end of the cylinder is conically shaped and terminates in a pointed tip.

In the latter there are situated inwardly opening non-return valves, which are shielded by protective grids. The cylinder is provided with supporting feet which are distributed about its periphery. The cylinder or conveying pipe can be provided with a buoyancy body which is adjustable as regards its specific gravity. The shaking movements are intended to assist penetration into the mud and to prevent the formation of channels which might possibly extend through the mud as far as the brine layer (see Federal German Laid Open Specification 2707899).

According to the present invention, there is provided conveying apparatus for conveying mud from great water depths, comprising conveying duct means which terminates at its outer end in a suction mouthpiece and a conveying pump communicating with said conveying duct means, the suction mouthpiece comprising a vibratory screen.

The screen may have a conical shape with a downwardly directed tip, the vibration direction being vertical.

This apparatus has the advantages that the material on the sea floor is loosened up by the vibrations, and thus the suction work is considerably facilitated, or the energy required reduced, that the screen keeps away obstacles which might endanger a conveying apparatus equipped with for example a centrifugal pump, and that the brine lying above the mud is also not sucked-in.

According to a preferred feature of the invention, the outer end of the conveying duct means is provided with pressurised water nozzles supplied from pressurised water duct means.

Thus, a plurality of pressurised water nozzles can be situated above the screen on the conveying ducts means. The water jets are directed preferably in the direction of the screen region, or the outer surface of the said screen. It is also possible to arrange pressurized water nozzles in the tip region of the conical screen, these being situated on a holder which extends inside the screen in the longitudinal direction and is arranged on the conveying duct means.

The additional application of water under pressure contributes to the loosening-up of the bed material. The application of water under pressure allows a controllable dilution and thorough mixing of the loosened-up material.

The apparatus can be constructed in various ways. In a simple constructional arrangement the conical screen is secured at its base on a supporting device which is guided with play on or in the outer end of a conveying conduit of the conveying duct means and is mounted to be capable of vibrating in the vertical direction. The outer end of the conveying conduit can carry a drive for vibrating the screen. The screen or the supporting device thereof can be attached to one end of a plurality of connecting bolts which are guided in the vibration direction and are provided at their other end with rollers bearing on a running surface of a rotary annulus which surrounds the conveying conduit and the running surface of which is provided with undulatory projections protruding in the vertical direction.

The connecting bolts can carry springs which bear at one end on the base of the vibrating screen and at the other end on an abutment provided on the conveying conduit. A preload is produced by this arrangement which presses the rollers always against the annulus.

By rotation of the annulus, the screen is moved up and down in accordance with the speed of rotation at an adjustable rate of vibration. When the lower end of the screen abuts against an object the screen disconnects automatically from the vibrating mechanism, so that the annulus freewheels.

For further protection of the drive, a centrifugal clutch can be arranged between the drive and the annulus.

In a simple constructional form, the annulus is mounted in self-aligning bearings.

Conveniently, the drive can be electrical and arranged in a housing encircling the lower end of the conveying conduit, the connecting bolts extending to inside the housing through watertight seals. The watertight seals can comprise diaphragm discs which are secured peripheraily on the connecting bolts and on the housing. The housing can be provided with an oil filling and connected by way of a conduit with a compensation reservoir.

The screen can be formed of trapezoidal wires.

To guide it, the vibrating screen can carry vertically situated guide plates at its external surface.

The suction head, comprised of the screen, its drive system and the conveying conduit, can be secured on a suction head shank comprising two concentric pipes the internal of which is a suction pipe, and the intervening space between which is used for the conveying of pressurised water. The suction head shank can comprise a plurality of pipe lengths, the inner lengths being connected to one another by means of plug and socket joints with O-ring sealing elements. The outer pipe lengths on the other hand can be provided with flanges and sealing elements for connection with one another.

The suction head, or suction head shank, can be connected by means of a spring damping part to the conveying piping leading to the surface. This keeps vibrations away from the conveying piping.

The spring damping part can also be provided with a travel distance pickup whereby excessive movements of the suction head relatively to the adjoining conveying piping are indicated. In this way it is possible to monitor in a simple manner for example whether vibrating screen comes to rest on the sea floor.

The pressurised water duct means can be provided with a secondary conduit for supplying cooling water to the drive.

In order that the invention may be clearly understood and readily carried into effect, reference will now be made, by way of example, to the accompanying drawings, wherein: Figure 1 shows a side elevation of conveying apparatus for conveying ore mud from great water depths, Figure 2 shows a sectional side elevation of an outer end zone of the apparatus on a larger scale, Figure 3 shows a sectional side elevation of a slightly higher zone of the apparatus, Figure 4 shows a sectional side elevation of a next higher zone of the apparatus, Figure 5 shows a side elevation of the next following zone of the apparatus, and Figure 6 shows pressurised water circuitry of apparatus.

Referring to the drawings, from the ship A conveying piping B goes towards the bottom of the sea. The fastening of the conveying piping to the ship is not shown in detail.

A suction pump D of a pump unit C is interposed in the piping B, the unit C also including a pressurised water delivery pump E which is supplied from the surrounding sea water.

Secured to the lower portion of the piping B is a section head shank G, this being secured by way of a spring damping part F. This shank comprises an inner pipe H and an outer pipe I each of which comprises a plurality of pipe lengths. The inner pipe H serves as a suction pipe. The intermediate space between the pipes H and I is used for the conveying of water under pressure and is connected via a flexible conduit K to the pressurised water pump E.

A suction head L is secured to the lower end of the suction head shank G.

At the lower end of the suction head is a vibratory screen 1 , which is of conical shape and at its base is connected to a supporting ring 2. The screen can be of fra me-type construction for reasons of strength. Between the closed tip 1 a of the screen 1 and the supporting ring 2 there are situated at the periphery three webs 3 between which individual screen segments are welded-in.

The screen segments can have a mesh width of 10 mm. To obviate blockages, they are made from trapezoidal individual wires. Over the three screen segments there are secured guide plates 4 which are conveniently connected on the one hand to the tip and on the other hand to the supporting ring 2.

The supporting ring 2 carries at its periphery three vertically guided connecting bolts 5 which are guided within a drive support 6.

A drive mechanism for vibrating the screen is arranged in the space between the suction pipe H and a protective casing M. There is secured a submersible electric motor 7 the axis of which its situated parallel to the suction pipe H and which by way of a pinion 8 drives a horizontal annular disc 9 through a toothed ring 9a connected with the disc and mounted on self-aligning roller bearings. This disc 9 is provided at its upper surface with three undulatory projections with identically shaped sine wave form, on which rollers 1 Oa run, the rollers 1 Oa being secured on a drive ring 10 which connects with one another the upper ends of the connecting bolts 5.During normal operation, continual bearing contact of the rollers 1 Oa on the annular disc 9 is ensured by springs 11 which permanently preload the connecting bolts 5 and prevent the rollers from lifting off. Thus the rotational movement of the annular disc produces a vibrating movement of scree 1.

If the springs 11 are subjected to a high upward load - e.g. by undesirably hard impact of the screen on the sea floor - the rollers 1 Oa are lifted off, and the annular disc 9 runs freely. The connecting bolts 5 are guided in plain bearing sleeves 12. The annular space between the drive support 6 and the housing M, which is completely filled with oil, is connected with a compensation vessel 1 3 for pressure balancing purposes.

The oil is used both for lubricating the movable parts and also for temperature exchange between the electric motor and the environment.

For further protection of the drive of the annular disc 9, a centrifugal clutch 14 is connected in between the motor 7 and the pinion 8.

To seal the connecting bolts 5 the latter are provided with rubber diaphragms 18 which are fixed at their external peripheries in the housing.

In the vicinity of the suction mouthpiece there are secured on the suction head L nozzles 1 5 which are connected by a ring main 1 5a with one another and with the pressurised water supply.

There is also arranged within the screen 1 a stationary nozzle holder 1 6 on the lower end of which there are secured nozzles 1 6a which are also connected to the pressurised water supply and extend through the tip 1 a of the screen. The nozzles 1 5 are arranged in groups with different jet directions. The pressurised water is used for removing obstacles and for loosening-up the mud bed. By modifying the total free outlet cross section, by interchanging nozzle inserts or by the closing of some nozzles, a considerable number of possible operating states can be achieved.

The suction head L comprises a support unit 21 which holds the suction head during assembly, surrounds the screen, and is used for protecting the suction head when it descends against relatively large lumps of rock or the like.

The spring damping part F mitigates transmission to the piping B of vibrations which may be transmitted from the vibrating screen to the drive support 6 and the shank G. At this region it is possible to measure the pressure with which the apparatus presses against the bed or the floor or the force required for drawing the apparatus out of the mud, with the use of an inductive travei pickup 22. Length variations of the piping B can be taken up within the spring damping part by means of a steel compensator.

The water under pressure required for the nozzles 1 5 and 1 6a is produced by the pressurised water pump E (referenced 31 in Figure 6.) which runs on the same shaft as the frequency-regulated main pump D. Since a coupling of this kind is disadvantageous for the winning operation, regulation of throughflow is effected by means of a flow controller 32. The design of the pressurised water pump E ensures that the nominal delivery or conveying rates are achieved even with the lowest main pump rotational speed.

A control piston of the flow controller 32 is moved with an electrically operated 4/3 way valve 33. The water under pressure is used as working medium for the flow controller 32 and the 4/3 way valve 33. The quantity of water under pressure is measured with a standard venturi nozzle 34 and a capacitive differential pressure pickup 35. For venting the control lines during descent, two nonreturn valves 36 and 37 preceded by filters are provided.

From the pump unit C which is situated at a water depth of approximately 2000 m, the water under pressure is conducted to the nozzles, which are about 200 m. deeper, with a rubber fabric flexible pipe 38 (referenced K in Figure 1).

Within the suction head L a part-flow of the pressurised water is used for cooling the motor 7.

A fixedly set differential pressure valve 39 connected in parallel opens when a quantity greater than is required for cooling flows through, and thus limits the pressure loss in the cooling device of the motor 7. After the valve the pressure water branches to the two nozzle arrangements above the screen 1 and in the screen tip 1 a.

The vibration of the screen in conjunction with its conical shape contributes to ensuring that obstacles which come to the screen periphery because of the suction current are moved in the direction of the screen tip 1a. In this way clogging of the suction zone is prevented.

A further object of the vibrations is to mix pressurised water and mud thoroughly. The vertical plates 4 which are provided also serve to transmit vibrations effectively into the bed.

The apparatus described with reference to the drawings can convey even muds of high viscosity over relatively long distances or under relatively high conveying pressures. The conveying is also capable of being used to convey muds at relatively high temperatures. The temperatures of the muds being conveyed may amount to up to about 8O0C.

The muds may have a specific gravity of 1.3 g/cm3, but muds of higher or lower specific gravity may also be conveyed. The apparatus is also intended more particularly to serve to convey orebearing muds from great depths, with a brinze zone of a relatively high specific gravity of for example 1.2 g/cm3 lying above the ore mud bed.

The conveying apparatus is made such that brine from this zone cannot get into the ore mud to be conveyed, or into the conveying apparatus. The ore muds to be conveyed may lie at a depth of about 2,500 m. on the sea floor and have a thickness of about 20 to 100 m. The viscosity of the mud can amount to about 120 c poises.

The orr mud is in a relatively firm layer or deposit which may have thixotropic properties.

The substance to be conveyed may be mixed with relatively large lumps such as for example lumps of basalt. The deposits may be covered with a roughiy 200 m. thick layer of concentrated brine.

Claims

1. Conveying apparatus for conveying mud from great water depth, comprising conveying duct means which terminates at its outer end in a suction mouthpiece, and a conveying pump communicating with said conveying duct means, the suction mouthpiece comprising a vibratory screen.

2. Conveying apparatus according to claim 1, wherein said screen is of conical shape with a tip which is directed downwardly when the apparatus is in use, and said screen is arranged to vibrate longitudinally of said conveying means.

3. Conveying apparatus according to claim 1 or 2, and further comprising pressurised water nozzle means in the region of said suction mouthpiece and pressurized water duct means for supplying said nozzle means.

4. Conveying apparatus according to claim 3, wherein said pressurised water nozzle means comprises pressurised water nozzles so situated as to be above the screen when the apparatus is in use.

5. Conveying apparatus according to claim 4, wherein the nozzles are directed towards a zone outwards of the screen or towards the outer surface of the screen.

6. Conveying apparatus according to claim 3, 4 or 5, as appended to claim 2, wherein said pressurised water nozzle means comprises pressurised water nozzles in the region of said tip.

7. Conveying apparatus according to claim 6, wherein said nozzles in the region of said tip are mounted on a holder which extends longitudinally inside the screen.

8. Conveying apparatus according to claims 2 or 6, or claims 3, 4 or 5 as appended to claim 2, wherein the screen is secured at the base of its conical shape to a supporting ring which is guidedly mounted on an outer end of a conveying conduit of said conveying duct means so as to be capable of vibrating longitudinally of the conveying duct means.

9. Conveying apparatus according to any preceding claim, wherein said outer end of the conveying duct means carries a drive arranged to vibrate the screen.

10. Conveying apparatus according to claim 9, wherein the screen is connected to one end of connecting means which is guided for vibratory movement longitudinally of the conveying duct means and the other end of which carries rollers bearing on a running surface of a rotary annulus which is connected to said drive and which encircles said conveying duct means, said running surface being provided with undulatory projections protruding longitudinally of said conveying duct means

11. Conveying apparatus according to claim 10, wherein said connecting means comprises elongate connecting members extending longitudinally of said conveying duct means.

12. Conveying apparatus according to claim 10 or 11, and further comprising spring means urging said connecting means towards said screen.

13. Conveying apparatus according to claim 12 as appended to claim 8, wherein said spring means acts between said screen and an abutment fixed to said conveying conduit.

14. Conveying apparatus according to claim 10, 11, 12 or 13, wherein the annulus is mounted on self-aligning bearings.

15. Conveying apparatus according to any one of claims 10 to 14, and further comprising a clutch arranged between the drive and the annulus for protection of the drive.

1 6. Conveying apparatus according to any one of claims 9 to 15, wherein said drive is arranged in a housing encircling the outer end of the conveying duct means.

17. Conveying apparatus according to claim 1 6 as appended to claim 10, wherein said connecting means extends to inside said housing through water-tight sealing means.

1 8. Conveying apparatus according to claim 17, wherein said water-tight sealing means comprises diagraphm means secured to said connecting means and to said housing.

1 9. Conveying apparatus according to claim 16, 17, or 18, wherein the housing is designed to be oil-filled and is connected by way of a conduit with a compensation reservoir.

20. Conveying apparatus according to any preceding claim, wherein the screen is formed of trapezoidal wires.

21. Conveying apparatus according to any preceding claim, and further comprising guide plates disposed at outside of said screen.

22. Conveying apparatus according to any preceding claim, wherein the suction mouthpiece forms part of a suction head which is secured to a suction head shank which consists of two concentric pipes the inner of which serves for the conveying of said mud under suction, and the intermediate space between which serves for the conveying of water under pressure.

23. Conveying apparatus according to claim 22, wherein the suction head shank comprises a plurality of lengths of piping, the inner lengths being connected to one another by means of plug and socket connections with sealing elements.

24. Conveying apparatus according to any preceding claim, wherein the suction mouthpiece is connected by way of a damping part to a conveying piping of said conveying duct means which conveying piping serves to lead to the water surface during use of the apparatus.

25. Conveying apparatus according to claim 24, wherein said damping part is provided with a travel pickup.

26. Conveying apparatus according to claim 9 as appended to claim 3, wherein the pressurised water duct means is provided with a secondary conduit for the supplying of cooling to said drive.

27. Conveying apparatus for conveying mud from great water depths, substantially as hereinbefore described with reference to the accompanying drawings.