US3881530A

US3881530A - Plant for evacuating dredged material

Info

Publication number: US3881530A
Application number: US347373A
Authority: US
Inventors: Giovanni Faldi
Original assignee: Giovanni Faldi
Current assignee: EPI SpA
Priority date: 1972-05-17
Filing date: 1973-04-03
Publication date: 1975-05-06
Anticipated expiration: 1992-05-06
Also published as: ES414263A1; JPS5019855B2; CH574020A5; JPS4955138A; ZA732240B; GB1425344A; IL42287A0; SE400795B; AR205690A1; IL42287A; CA979840A; FR2184616B1; AU5425073A; DE2316763A1; FR2184616A1; IT956280B

Abstract

A plant for evacuating dredged material is disclosed, according to which the dredged material, in form of aqueous suspension of high solid content, is loaded into transporting lighters, of the type comprising a closed loading cavity, having an upper loading inlet and a lower discharge connection, and the lighters shuttle between the dredging apparatus and a flow floating station, provided with at least a pneumatic pump, per se known, and with means for connecting the intake duct of said pump with said discharge connection of the lighter.

Description

United States Patent 1 Faldi May 6, 1975 [54] PLANT FOR EVACUATING DREDGED 3,426,715 2/1969 l14/27 MATERIAL 3,528,462 9/1970 Quase........ 141/284 3,595,278 7/1971 Lilly et 141/1 [76] Inventor: Giovanni Faldi, via Forese Donati 27, F1 t 1 Creme 1 a y Primary Examiner-R1chard E. Aegerter Filedi Apr. 3, 1973 Assistant ExaminerFrederick R. Schmidt Appl. No.: 347,373

Foreign Application Priority Data May 17, 1972 Italy 24498172 US. Cl. 141/284; 114/27; 141/312; 141/388; 214/13; 214/15 B Int. Cl B631) 35/30 Field of Search 61/721; 114/27, 36; 141/1, 67,113, 279, 284, 287, 311, 312,

References Cited UNlTED STATES PATENTS Jessup 114/36 Attorney, Agent, or Firm-Karl W. Flocks [57] ABSTRACT A plant for evacuating dredged material is disclosed, according to which the dredged material, in form of aqueous suspension of high solid content, is loaded into transporting lighters, of the type comprising a closed loading cavity, having an upper loading inlet and a lower discharge connection, and the lighters shuttle between the dredging apparatus and a flow floating station, provided with at least a pneumatic pump, per se known, and with means for connecting the intake duct of said pump with said discharge connection of the lighter.

4 Claims, 6 Drawing Figures F SEE'MEE HAY 819. 5

SHEH 30? 6 I I I I u I I PMENTEU HAY 5 SHEET 5 OF 6 1 PLANT FOR EVACUATING DREDGED MATERIAL The present invention relates to a plant for discharging and transporting to a distance refuse material of semi-solid or pulp form, particularly suitable for material dredged from submerged beds.

In dredging marine or lacustrine beds, the essential problem always exists of eliminating the dredged material. In particular, when the dredging plant is mounted on floating pontoons or watercraft, recourse is normally made to transporting lighters which are filled with the dredged material and shuttle between the dredging zone and the zone in which discharge takes place.

However this system is subject to various disadvantages, mainly of an economical nature and relating to the length of the operations.

In fact normally the material loaded into the lighters, especially if pumped with dredges provided with impeller pumps, contains a very high percentage of water in order to permit loading and especially discharge with normal pumping plants. is evident that the superfluous transportation to a distance of such a large quantity of water affects the costs of the dredging operations. In addition, as the zones to be dredged are normally fairly extensive, the journey which the lighters have to make is usually fairly long. As these are relatively slow watercraft, it is clear that this influences the length of the dredging operations or the investment costs in terms of number of watercraft.

Finally in some cases, where the purpose of the dredging is also to free the bed from polluting and dangerous material, for example hydrocarbon sludge, mercury compounds and others, the dredged material must be loaded on to lighters and transferred a great distance in order to avoid new pollution of the same dredged zone or others adjacent. In these cases moreover it is unadvisable to use buckets which by moving the bed would cause a second pollution, aided by the currents.

Dredging plants exist (the subject of previous patents and patent applications by the same applicant), mounted on pontoons and consisting of pumping units provided with dredging shovels which are submerged, the dredging shovels of which engage with the bed, disaggregating it and conveying the material towards pumping chambers or cylinders operating by compressed air, and from which the material mixed with water is conveyed to the surface by means of a flow pipe. The main advantage of these dredging plants is the flexibility of application, both in terms of the depth of dredging and of the type of bed dredged, plus a high dredging efficiency and a reduced water content of the dredged material.

Flow plants are also known, and constitute the subject of a previous patent application by the same applicant, in which pneumatic pumps of the same type as the aforementioned are used in combination with loading tanks for conveying to a distance material in the form of an aqueous suspension of high solid content. These plants are particularly useful for conveying to a distance industrial waste, and for example for the reclaiming of beaches and the like.

It has now been found, and constitutes the main object of the present invention, that the problems briefly mentioned previously are completely resolved to great advantage by a plant for conveying and discharging at a distance dredged material in the form of an aqueous suspension, in which the dredged material is loaded into distance transporting lighters, of the closed type, characterised in that it comprises a floating flow station provided with a plurality of pneumatic flow pumps, the inlet pipe of each pump being arranged for removable connection to the outlet of a transporting lighter suitable for shuttling between the dredging plant and said flow station, further characterised in that said lighter, provided or not provided with autonomous drive means, comprises a completely closed loading cavity in which an upper aperture is provided for loading the dredged material, and a discharge connection situated on the bottom at one end of said cavity, in which there are also provided means for conveying to said connection the dredged material which fills the cavity of the lighter, and from there by way of a flexible pipe to said inlet pipe.

In a first particularly preferred embodiment of the present invention, said means for conveying the dredged material which fills the loading cavity of the lighter consist of a conveying shovel mobile within the cavity from a position at the end of the lighter furthest from said end in which said discharge connection is formed, to this latter end of said cavity.

In a further embodiment of the invention, usable in particular when the dredged material has a lower percentage of solids, said conveying means consist of a header situated inside said cavity along its longitudinal axis, said header comprising a plurality of apertures distributed along its axis such as to allow the gradual discharge of the dredged material, one end of said header being connected to said discharge connection.

In a further preferred embodiment of the present invention, the flow station is characterised, besides the submerged flow pump, also by comprising a mooring system for the lighters, provided with fixed mooring points for disposing the lighter and in particular its discharge connection in a predetermined required position with respect to the submerged pump, and also in that means are provided for bringing the inlet pipe of the submerged pump into tight communication with the discharge connection of the lighter.

One of the main advantages of the present invention lies in the fact that it is possible to convey the dredged material away from the dredging zone with minimum transportation costs by lighters, and transporting a minimum quantity of superfluous water, since the concentration of solids in the dredged material transported by the lighters and pumped by the flow station can reach A further similarly important advantage is that by this system, the dredged material passes from the dredging pump to the discharge zone without any loss, and hence if it should be polluted any repollution is consequently avoided.

A further advantage is that the mooring and discharge operations of the lighters at the flow station are facilitated and made rapid, independently of the conditions of the sea, lake, river and the like.

These and further aspects and advantages of the present invention will be more evident from the following description given in relation to the accompanying drawings in which:

FIG. 1 is a schematic view of the plant according to the present invention;

FIG. 2 is an analogous view of the plant in the working stage;

FIG. 3 is a view of a detail of a possible variation;

FIGS. 4 and 5 are a frontal and lateral schematic view respectively of the particular embodiment of the flow station for the mooring and discharge of the lighters loaded with dredged material, of which FIG. 6 shows a variation.

FIG. 1 shows the essential parts of the plant according to the present invention, i.e. the transporting lighter B and the pumping station P.

This latter comprises a floating pontoon 10 on which are mounted the air compressor and distributor 12 for the operation of the submerged pumping unit 13.

This latter, suspended by a cable 16 from a support arm 14, comprises a plurality of pneumatic pumping chambers or cylinders (normally three in number) to which, according to a sequence determined by the distributor 12 of known type, compressed air arrives through the pipe 17, whereas the

pipes

18 and 19 constitute the inlet and discharge respectively for the dredged material.

The cable 20, which is adjustable, supports the flanged connection end of the pipe 18.

It must be emphasised that the floating pontoon or platform P may comprise a plurality of submerged pumping units 13, according to the capacity of the plant and especially of the hourly capacity of the dredging section.

As the operation of the pumping unit is well known from previous technology, no detailed description will be given of it.

Considering now the transporting lighter B, this comprises a hull 21 with an internal cavity 22 for filling with the dredged material 23, closed upperly by a cover or bridge 24 comprising a funnel loading mouth 25 (possibly closable by a gate valve) so as to avoid the emergence of polluting gases which are released from the dredged material.

At one end of the cavity 22 is provided a flanged discharge connection 26, to which a flexible pipe 27 is connected, its free end being suspended in an adjustable manner by means of a cable 28 from a raising arm 29 mounted on the bridge 24. Within the cavity 22 is mounted a conveying shovel 30, mobile along the longitudinal axis of the lighter by means of dragging cables 31 passing around intermediate pulleys 32 and driven by the winch 33. Return cables 34 are driven by the winch 35.

As seen clearly from FIGS. 1 and 2, the front surface of the shovel 30 is shaped so as to cause the dredged material 23 to be conveyed towards the discharge connection 26.

Considering in particular FIG. 2, when the lighter B has been brought close to the pumping station P, the two ends of the

pipes

27 and 18 are connected, after which the winch 33 is operated and the shovel 30 is dragged towards the other end of the cavity 22, so causing in this manner the discharge of the material 23 which alternately fills the various cylinders of the pneumatic pumping unit 13, from which the material 23 is made to flow to the required distance.

It has been found in this manner that the material 23 may reach a solid content of up to 85%, a figure which enables the advantage attained by the present invention to be completely appreciated.

Suitable sliding guides are provided for the sliding of the shovel 30. Any equivalent solution may also be provided, for example the discharge connection 26 in a central position and two symmetrical shovels which approach from the ends towards the centre.

Furthermore, any analogous system, for example a system with pneumatic or hydraulic pistons, may be employed for pushing the shovel 30 during the discharge stage of the dredged material 23.

FIG. 3 shows a variation concerning essentially the lighter and useful in those cases in which the dredged material has a less high solid content and hence a considerably lower viscosity. In this case, for conveying the dredged material to the outside of the cavity 22, a pipe or header 36 is fitted provided with apertures 37 through which the dredged and fairly fluid material passes by gravity into the pumping cylinders of the pneumatic pumping station P.

In the plant described with reference to FIGS. 1-3, the discharge pipe connected to the discharge connection of the lighter must be connected to the inlet pipe of the submerged flow pump. This system has the advantage of flexibility and rapidity of transfer from one place of work to another, jointly with the movements of the actual dredging plant, but in practice a certain time may be necessary for connecting the two sections of pipe, as they are normally of a certain size and hence not easily manageable, especially under rough sea conditions.

The purpose of the modification shown in FIGS. 4 and 5 is to make the connecting operations much more rapid, even though it requires a more complex and preferably fixed installation, which is however economically justified in the case of work of a certain size, because of the saving in time, the saving of labour and the possibility of removing the connecting operation from dependence on the ability of the operators. The principle on which the system shown in FIGS. 4 and 5 is based is that of providing mooring points for the lighters so that they are always in the correct position with respect to the submerged flow pump.

For this purpose the lighter 21 has its discharge connection 26 controlled by a discharge valve 50 (in its turn controlled hydraulically, pneumatically or manually), provided with a wide flange 51 against which the flat flange 52 complete with a rubber seal gasket 53, and at which the inlet pipe 18 of the submerged pump 13 finishes, is tightly fitted. The flange 52 constitutes the final part of a funnel connection 54 to which the pipe 18 is generally coaxially fixed. The funnel connection 54 is in its turn rigid with an annular floating element 55, preferably a tubular ring full of air and having such a volume as to guarantee the tendency of the entire assembly (tubular ring, funnel and inlet pipe of the pump) to float.

As can be seen in FIGS. 4 and 5, the floating tubular element is anchored at the bottom by a set of four cables 56 controlled by way of intermediate pulleys 57 by four synchronised drums 58 or a single winch with four drums. Both the pulleys S7 and winches 58 are mounted either on two palisade structures 59, preferably of the type comprising foundation piles 60 sunk into the bed and supporting the platfonns 61, which also support the other equipment necessary both for the operation of the submerged pump (motor driven compressor, distributor etc.) and for its raising and lowering (for example shears and cable) or on two pontoons provided with retractable legs resting on the marine bed.

The palisade structure or pontoons 59 form a corridor of predetermined dimensions into which one or more lighters enter one after the other and moor in a precise predetermined central position with respect to the floating assembly comprising tubular ring, funnel and flange.

For this purpose it is necessary that all lighters have the same external shape (possibly comprising some external facing of wood or the like) so that they may be moored in said corridor and each discharge connection be located at the said respective floating assembly.

The operation of this variation of the present invention is as follows:

When the lighter arrives in the discharge zone it is directed by its own means or is pushed into the corridor formed between the two palisade structures until it strikes against a point of arrest previously constructed (indicated by the reference numeral 62) so giving the assurance that the discarge connection 26 and relative plate 51 lie in a position corresponding with the funnel which tends to rise by the action of the floating tubular ring full of air. Any slight differences may be neglected in that the funnel has an inlet mouth of much greater diameter than the diameter of the discharge connection of the lighter.

The floating assembly (floating tubular ring, pipe and funnel) will be anchored below the bottom of the lighter when it arrives, by the set of cables 56. When the lighter has been anchored at the correct point, the raising winch is operated so as to enable the inlet pipe of the pump to be raised and hence the terminal cone or funnel by the action of the floating tubular ring until the plate of the cone rests with its rubber gasket on the plate surrounding the discharge pipe positioned on the bottom of the lighter.

When the cables 56 which pull the floating tubular ring downwards become slack, this signifies that there is perfect adhesion between the two plates and hence the discharge valve may be opened and the emptying of the lighter and pumping to a distance may be commenced.

As the lighter empties it tends because of its smaller weight to float to a greater extent and raise itself from the water, but as the cables of the four drum winch or the four synchronised winches are idle, the floating tubular ring automatically maintains the contact between the cone and discharge tube by rising, so avoiding any dispersion of material, which may be polluted, into the zone where the work is carried out.

When the lighter has been emptied, operations are carried out in the reverse direction, i.e. firstly the discharge valve is closed, then by means of the four drum winch or the four synchronised winches the floating tubular ring is pulled downwards while continuing to pump for a short period of time so as to completely clean the inlet pipe and pump body.

As soon as the funnel and relative plate of the discharge pipe have been sufficiently removed, the lighter may be immediately re-transported back to the dredging plant.

If it is thought that the material with which the lighter is filled is not sufficiently fluid, one of the systems described hereinafter may be applied in order to facilitate unloading, or water may be added by a suitable pump.

Obviously the corridor which has been described as formed from palisade structures may also be constructed in the form of two or a series of strong pontoons provided with retractable legs for resting on the bed or from pontoons firmly anchored, but this system is less practical in the case of zones with large tide differences, because it requires the continual variation of the length of the cables fixing the pipes which would have to maintain a perfectly rigid corridor for the entry of the lighters.

instead of using means for forming a corridor, in some cases it is possible using the same means (platform on palisade, pontoon on retractable legs or anchored pontoon) to obtain the same results by bringing the lighter or lighters to the side of these means, which in this case would act as a quay.

FIG. 6 shows diagrammatically the modification in which instead of a corridor a mooring pontoon is pro vided, to which the lighters to be discharged are brought alongside.

The embodiment of FIG. 6 can be more practical and more easily adaptable even in the case of open sea, especially using pontoons with retractable legs, because it avoids disturbances due to the difference in level of the tide, and the need to construct fixed works which are difficult to recover, and further it enables very rapid dislocation both at the beginnig and at the end of the work in the case of a sea storm.

For this purpose it is sufficient to provide the pontoons with a suitable system for raising the conveyed pump body and the relative floating and conveying equipment so that it may be raised without altering the profile of the watercraft in the water and hence without hindrance to its movement.

A further solution especially for lighters which are not self-propelled and which would enable one or more lighters to be easily towed by a single tug, or with a further tug at the rear in the case of a number of lighters, and which facilitates a more rapid mooring, is represented by one or more pontoons in a row so as to construct a quay, moored either by means of anchorages or on retractable legs resting on the bed, in which the pump body and the systems for raising the floating tubular ring to be applied to the bottom of the lighter are firmly supported by the pontoons.

Previously the floating tubular ring has been shown always full of air and pulled downwards at the end of operations by a winch and cables, but the system may be equally realised by emptying the tubular ring of the air and filling it with water when the inlet cone is to be lowered, and carrying out the reverse operation when it is to be raised.

From the foregoing description it will be clear that the present invention provides an excellent solution to the problem of eliminating dredged material, especially enabling the wasteful transport and flow of large quantities of water to be avoided and reducing considerably the shuttle times of the lighters.

Although explicit reference has been made to dredging plants, other applications of the plant according to the invention are not excluded, for example for eliminating industrial waste, if in the form of a suspension in a liquid.

What I claim is:

1. A plant for conveying and discharging at a distance dredged material in the form of an aqueous suspension, in which the dredged material is loaded into lighters at a dredging station for transport to a distance, characterized in that said plant comprises a floating flow pumping station provided with at least one and preferably a plurality of submerged pneumatic flow pumps, having, respectively, a plurality of inlet pipes at least one transporting lighter selectively operatively connected to or disconnected from said floating flow pumping station, said transporting lighter having a discharge connection, the inlet pipe of each pump being removably connected to the discharge connection of the transporting lighter arranged for shuttling between the dredging station and said floating flow pumping station, further characterized in that said lighter, provided preferably with its own drive means, comprises a completely closed loading cavity with an upper aperture for receiving the dredged material and a discharge aperture situated in the bottom of the cavity, said discharge aperture being arranged for connection by way of said discharge connection to said flow pump inlet pipe in said floating station, means provided in said cavity for conveying the dredged material filling said cavity towards said discharge aperture, said flow station comprises in addition to at least one submerged pneumatic flow pump a mooring corridor for the lighters, provided with fixed mooring points such as to dispose the lighter and in particular its discharge connection in a predetermined position with respect to the submerged pump and in which are further provided means for bringing the inlet pipe of the submerged pump into tight communication with the discharge connection of the lighter, and said means for bringing the inlet pipe of the submerged pump into tight communication with the discharge connection of the lighter comprising a part shaped as a funnel generally coaxial with said inlet pipe and rigid with the free end of said inlet pipe, said funnel part terminating in a flat flange fitted with a seal gasket, arranged to mate with a flat flange formed on the bottom of the lighter at and concentric with said discharge connection, and means anchored adjustably downwards and rigid with said funnel part to ensure that the funnel part floats.

2. A plant as claimed in claim 1, in which said mooring corridor comprises palisade elements anchored to the bed of a body of water and supporting two platforms on which the necessary equipment for the operation of the submerged pump is mounted.

3. A plant as claimed in claim 2, in which said means which ensure that the funnel part floats consist of an annular tube element suitable for filling with air, cables fixed to said tube element and operatively connected to synchronised members mounted on said platforms and by which said float may be pulled downwards by said synchronised members.

4. A plant as claimed in claim 1, in which said mooring corridor comprises two or more floating pontoons provided with telescopic legs for resting on the bed of a body of water so as to make the entire assembly stable, said pontoons being adapted to support equipment associated with said pump.